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A preliminary protocol for prescribing upper limb prostheses Bhuanantanondh, Petcharatana 2012

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 A PRELIMINARY PROTOCOL FOR PRESCRIBING UPPER LIMB PROSTHESES   by    PETCHARATANA BHUANANTANONDH     A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF   DOCTOR OF PHILOSOPHY  in   THE FACULTY OF GRADUATE STUDIES  (Biomedical Engineering)   THE UNIVERSITY OF BRITISH COLUMBIA  (Vancouver)   October 2012    © Petcharatana Bhuanantanondh, 2012  ii         Abstract    Selecting an appropriate prosthesis is a complex process.  To the best of our knowledge, to date there is no standard prescription protocol for upper limb prostheses. Thus, the primary objective of this study was to propose a prescription protocol for upper limb prostheses. To understand more about the properties of the prosthetic terminal device; frictional properties of the contact surfaces between terminal devices and the grasped object, and the effect of loading rates on the frictional properties of the terminal devices were evaluated. The results showed that metal is better gripped by the body-powered hook than by the myoelectric hand; whereas plastic and wood are better gripped by the myoelectric hand than by the body-powered hook.   In addition, as loading rate increases, the friction coefficient decreases. With regard to the prescription protocol for upper limb prostheses, this study proposed a prescription protocol that not only contains comprehensive information, but also proposed a scoring system to assist in selecting an appropriate prosthesis.  The scoring system was developed by factorial survey approach.  Five factors affecting the type of upper limb prosthetic device were selected for vignette constructions.   Twenty upper limb prosthetic experts were involved in this study.  Each participant was asked to rate 20  iii vignettes regarding the appropriateness in selecting a myoelectric prosthesis for an individual with upper limb amputation.  The findings from the factorial survey analysis suggested that “work condition” is the most critical factor that influences the judgments of the upper limb prosthetic experts in making the selection of prosthetic devices for both trans-radial and trans-humeral amputation. The proposed scoring system was also evaluated for its effectiveness.  The study suggests that the proposed scoring system may be improved as a tool to assist in the selection of an appropriate prosthetic device. In conclusion, this study suggested that the frictional coefficients of the terminal devices and the grasped objects are dependent on the material and the loading rate.  “Work condition” is a key factor in selecting an appropriate prosthesis for the upper limb amputee, and a systematic evaluation of an amputee’s condition is useful in selecting an appropriate prosthetic device.  iv     Table of Contents  Abstract…………. ................................................................................................................. ii Table of Contents .................................................................................................................. iv List of Tables.. ...................................................................................................................... ix List of Figures.. ................................................................................................................... xiii Acknowledgements ............................................................................................................... xv Dedication....... .................................................................................................................... xvi Chapter 1   Introduction .......................................................................................................... 1 1.1 Overview ................................................................................................................. 1 1.2 Research Motivation ............................................................................................... 3 1.3 Research Objectives ................................................................................................ 5 1.4 Thesis Organization ................................................................................................ 6 1.5 Expected Contribution from the Current Study ...................................................... 7 Chapter 2   Literature Review ................................................................................................. 8 2.1 Etiology of Upper Limb Amputation ...................................................................... 8 2.2 Upper Limb Prostheses ......................................................................................... 10 2.2.1 Cosmetic Prosthesis ...................................................................................... 10 2.2.2 Body-Powered Prosthesis ............................................................................. 11  v     2.2.2.1   Suspension and Control Systems ................................................................ 12     2.2.2.2   Terminal Devices ........................................................................................ 14     2.2.2.3   Wrist Units .................................................................................................. 15             2.2.2.4   Elbow Units ................................................................................................ 16     2.2.2.5   Shoulder Units ............................................................................................ 18 2.2.3 Myoelectric Prothesis ................................................................................... 18     2.2.3.1   Sockets ........................................................................................................ 20     2.2.3.2   Terminal Devices ........................................................................................ 20     2.2.3.3   Wrist Units .................................................................................................. 21             2.2.3.4   Elbow Units ................................................................................................ 22             2.2.3.5   Shoulder Units ............................................................................................ 22 2.3 Body-Powered Prosthesis vs. Myoelectric Prosthesis .......................................... 23 2.4 Prosthetic Acceptance and Abandonment ............................................................ 25 2.5 Return-to-Work After Amputation ....................................................................... 28 2.6 Functional Range of Motion Analysis .................................................................. 30 2.7 Prosthetic Prescription .......................................................................................... 32 2.8 Summary ............................................................................................................... 35 Chapter 3   Frictional Properties of Terminal Devices ......................................................... 37 3.1 Friction .................................................................................................................. 38 3.1.1 Principles of Friction .................................................................................... 38 3.1.2 Stick Slip Motion .......................................................................................... 41 3.1.3 Effect of Loading Rate .................................................................................. 42 3.2 Slip Measurements of Terminal Devices .............................................................. 43  vi 3.2.1 Parameters ..................................................................................................... 43             3.2.1.1   Types of Terminal Devices ......................................................................... 43             3.2.1.2   Types of Materials ...................................................................................... 44             3.2.1.3   Loading Rates ............................................................................................. 44 3.2.2 Apparatus ...................................................................................................... 45             3.2.2.1   Body-Powered Split Hook .......................................................................... 45             3.2.2.2   Otto Bock Myohand DMC VariPlus Speed ®  .............................................. 46             3.2.2.3   Instron DynaMight ...................................................................................... 47             3.2.2.4   FlexiForce ®  Sensor ..................................................................................... 48             3.2.2.5   Spring .......................................................................................................... 49 3.2.3 Procedures ..................................................................................................... 51             3.2.3.1   Normal Force ( N F ) Measurement for Body-Powered Split hook ............. 51             3.2.3.2   Normal Force ( N F ) Setting for Otto Bock Myohand DMC Variplus                           Speed ®  ......................................................................................................... 52             3.2.3.3   Examining the Frictional Properties of the Materials in Contact between Body-Powered Spilt Hook and Gripped Objects ........................................ 53             3.2.3.4   Examining the Frictional Properties of the Materials in Contact between Otto Bock Myohand DMC VariPlus Speed ®  and Gripped Objects ............ 54 3.3 Frictional Properties of Terminal Devices ............................................................ 56         3.3.1        Static Friction Coefficients of Body-Powered Split Hook vs. Otto Bock Myohand DMC VariPlus Speed ®  ................................................................. 57         3.3.2        Effects of Loading Rates on Coefficient of Friction of Terminal Devices ... 59 3.4 Conclusion ............................................................................................................ 65  vii Chapter 4   Prescription Protocol for Upper Limb Prostheses .............................................. 68 4.1 Factorial Survey Approach ................................................................................... 71 4.2 Factorial Vignettes and Analysis .......................................................................... 74 4.2.1 Development of the Vignettes ...................................................................... 74 4.2.2 Vignette Administration ............................................................................... 77 4.2.3 Data Analysis ................................................................................................ 77             4.2.3.1   Regression Model ....................................................................................... 78             4.2.3.2   Overall Model Fit and Effects of Individual Variables .............................. 83 4.3 Vignette Ratings ................................................................................................... 87 4.3.1 Trans-Radial Amputation ............................................................................. 87 4.3.2 Trans-Humeral Amputation .......................................................................... 90 4.4 Factors in Selecting the Types of Upper Limb Prostheses ................................... 93 4.5 Prescription Protocol for Upper Limb Prostheses ................................................ 95 4.5.1 Overview of the Prescription Protocol .......................................................... 96 4.5.2 Scoring System in the Prescription Protocol ................................................ 97 4.5 Conclusion .......................................................................................................... 101 Chapter 5   Evaluation of the Scoring System .................................................................... 104 5.1 Anonymous Cases’ Characteristics .................................................................... 106 5.2 Occupations and Causes of Amputation ............................................................. 107 5.3 Expectation and Psychosocial Functioning ........................................................ 107     5.4       Evaluation of the Proposed Scoring System for Tran-Radial Amputation ......... 110 5.4.1 Case 1 .......................................................................................................... 111 5.4.2 Case 2 .......................................................................................................... 112  viii 5.4.3 Case 3 .......................................................................................................... 113 5.4.4 Case 4 .......................................................................................................... 114 5.4.5 Case 5 .......................................................................................................... 115 5.6 Evaluation of the Proposed Scoring System for Tran-Humeral            Amputation .......................................................................................................... 116 5.5.1 Case 6 .......................................................................................................... 116 5.5.2 Case 7 .......................................................................................................... 118 5.5.3 Case 8 .......................................................................................................... 119 5.5.4 Case 9 .......................................................................................................... 120 5.6 Conclusion .......................................................................................................... 121 Chapter 6   Conclusions and Future Work .......................................................................... 124 6.1 Conclusions ......................................................................................................... 124 6.2 Recommendations for Future Work ................................................................... 126 6.6.1 Frictional Properties of Terminal Devices .................................................. 126 6.6.2 Prescription Protocol for Upper Limb Prostheses ...................................... 127 References…… ................................................................................................................... 130 Appendices….. .................................................................................................................... 146 Appendix A: List of Vignettes  ................................................................................... 146 Appendix B: Example of Factorial Survey ................................................................. 148 Appendix C: Proposed Prescription Protocol for Upper Limb Prostheses ................. 151       ix     List of Tables  Table 3.1 Static friction coefficients ( S µ ) of the materials in contact between the body- powered split hook and different types of materials at various loading rates ....................... 58 Table 3.2 Static friction coefficients ( S µ ) of the materials in contact between the Otto Bock Myohand DMC VariPlus  Speed ®  and different types of materials at various loading rates ....................................................................................................................................... 58 Table 4.1 Vignette dimensions and levels ............................................................................ 75 Table 4.2 Sample vignette .................................................................................................... 76 Table 4.3 Example of survey responses ................................................................................ 81 Table 4.4 Example of dummy coding variables from the survey responses  ....................... 84 Table 4.5 Trans-radial amputation: The percentage of respondents’ selection for the rating scores from 1 to 9 (N = 400) ................................................................................................. 87 Table 4.6  Regression summary: The effects of upper limb prosthetic selection characteristics on the ratings of the appropriateness in fitting with a myoelectric device for trans-radial amputation (N = 400) ........................................................................................ 89 Table 4.7 Regression of rating on effect-coded dimensions for trans-radial amputation (N = 400) ............................................................................................................................... 90  x Table 4.8 Trans-humeral amputation: The percentage of respondents’ selection for the rating scores from 1 to 9 (N = 400). ..................................................................................... 91 Table 4.9 Regression summary: The effects of upper limb prosthetic selection characteristics on the ratings of the appropriateness in fitting with a myoelectric device for trans-humeral amputation (N = 400) .................................................................................... 92 Table 4.10 Regression of rating on effect-coded dimensions for trans-humeral amputation (N = 400) ............................................................................................................................... 93 Table 4.11 Scoring system for trans-radial amputation ........................................................ 99 Table 4.12 Scoring system for trans-humeral amputation  ................................................. 100 Table 4.13 Example of how to utilize the proposed scoring system .................................. 101 Table 5.1 Cases’ Characteristics ......................................................................................... 106 Table 5.2 Summary of occupations before amputation, after amputation and causes of amputation .......................................................................................................................... 108 Table 5.3 Summary of expectation  .................................................................................... 109 Table 5.4 Summary of psychosocial functioning ............................................................... 110 Table 5.5 Case 1: Occupation after amputation, physical assessment and work description  .......................................................................................................................... 111 Table 5.6 Scoring system for trans-radial amputation: Type of prosthesis recommendation for Case 1 ............................................................................................................................ 111 Table 5.7 Case 2: Occupation after amputation, physical assessment and work description  .......................................................................................................................... 112 Table 5.8 Scoring system for trans-radial amputation: Type of prosthesis recommendation for Case 2 ............................................................................................................................ 112  xi Table 5.9 Case 3: Occupation after amputation, physical assessment and work description  .......................................................................................................................... 113 Table 5.10 Scoring system for trans-radial amputation: Type of prosthesis recommendation for Case 3 ............................................................................................................................ 113 Table 5.11 Case 4: Occupation after amputation, physical assessment and work description  .......................................................................................................................... 114 Table 5.12 Scoring system for trans-radial amputation: Type of prosthesis recommendation for Case 4 ............................................................................................................................ 115 Table 5.13 Case 5: Occupation after amputation, physical assessment and work description  .......................................................................................................................... 115 Table 5.14 Scoring system for trans-radial amputation: Type of prosthesis recommendation for Case 5 ............................................................................................................................ 116 Table 5.15 Case 6: Occupation after amputation, physical assessment and work description  .......................................................................................................................... 117 Table 5.16 Scoring system for trans-humeral amputation: Type of prosthesis recommendation for Case 6 ................................................................................................ 117 Table 5.17 Case 7: Occupation after amputation, physical assessment and work description  .......................................................................................................................... 118 Table 5.18 Scoring system for trans-humeral amputation: Type of prosthesis recommendation for Case 7 ................................................................................................ 118 Table 5.19 Case 8: Occupation after amputation, physical assessment and work description  .......................................................................................................................... 119  xii Table 5.20 Scoring system for trans-humeral amputation: Type of prosthesis recommendation for Case 8 ................................................................................................ 120 Table 5.21 Case 9: Occupation after amputation, physical assessment and work description  .......................................................................................................................... 120 Table 5.22 Scoring system for trans-humeral amputation: Type of prosthesis recommendation for Case 9 ................................................................................................ 121 Table 5.23 Recommended type of prosthesis from the scoring system in the prescription protocol ............................................................................................................................... 123  xiii     List of Figures  Figure 2.1 Body-powered prosthesis .................................................................................... 12 Figure 2.2  Examples of wrist units: (a) friction wrist unit; (b) wrist flexion unit ............... 16 Figure 2.3 Examples of elbow units (a) mechanical elbow unit; (b) single axis hinge ...................................................................................................................................... 17 Figure 2.4 Myoelectric prosthesis ......................................................................................... 19 Figure 2.5 Electric wrist rotation unit ................................................................................... 21 Figure 2.6 Electric elbow unit ............................................................................................... 22 Figure 3.1 Typical experimental setup for stick-slip motion ................................................ 41 Figure 3.2 Tangential friction force versus time of a typical stick-slip cycle ...................... 42 Figure 3.3 Body-powered split hook .................................................................................... 46 Figure 3.4 Otto Bock Myohand DMC VariPlus Speed ®  ...................................................... 47 Figure 3.5 Instron DynaMight .............................................................................................. 47 Figure 3.6 FlexiForce ®  sensor .............................................................................................. 48 Figure 3.7 Conductance curve for FlexiForce ®  sensor calibration (The error bars indicate standard deviation) ................................................................................................................ 49 Figure 3.8 Spring’s constant characterization ....................................................................... 50 Figure 3.9 Normal force setting for Otto Bock Myohand DMC VariPlus Speed ®  .............. 52  xiv Figure 3.10 Experimental set up for body-powered split hook ............................................ 54 Figure 3.11 Experimental set up for Otto Bock Myohand DMC VariPlus Speed ®  .............. 55 Figure 3.12 Typical tangential friction force versus time for slip measurements ................ 56 Figure 3.13 Static friction coefficient of the surfaces in contact between terminal devices and metal vs. load rate coefficient: comparing between body-powered split hook with neoprene lining and  myoelectric hand with PVC glove ...................................................... 60 Figure 3.14 Static friction coefficient of the surfaces in contact between terminal devices and plastic vs. load rate coefficient: comparing between body-powered split hook with neoprene lining and  myoelectric hand with PVC glove ...................................................... 62 Figure 3.15 Static friction coefficient of the surfaces in contact between terminal devices and wood vs. load rate coefficient: comparing between body-powered split hook with neoprene lining and  myoelectric hand with PVC glove ...................................................... 63   xv     Acknowledgments                I would like to express my sincere gratitude to my supervisor Dr. Ezra Kwok for being a truly excellent supervisor and mentor.  I am grateful for his generous support, guidance, and encouragement throughout my study.  I also would like to thank my supervisory committee, Dr. Dana Grecov, and Professor Bruno Jaggi for their guidance and support.             I also would like to thank Anthony Chan for his guidance and Laurent Lejeune for his help in data collection.             I am also grateful for the financial support provided by the Worker’s Compensation Board of British Columbia.             Finally, I would like to express my deepest gratitude to my parents and my brother for their unconditional love and support.       xvi     Dedication                I would like to dedicate this thesis to my parents and my brother.  I thank them for their unconditional love and support and encouraging me to be persistent in achieving my goals.      1     Chapter 1 Introduction 1.1 Overview Each year, an estimated 158,000 persons are admitted to hospitals to undergo amputations (Dillingham et al., 2002).  In 2005, there were approximately 1.6 million amputees in the United States; 8% of these are upper limb amputations (Ziegler-Graham et al., 2008).  Upper limb amputation can result from congenital malformation, vascular disease, malignancies, or traumatic injuries.  Studies reported that the work-related amputation injury rates are highest in industrial and agricultural works (Boyle et al., 2000; Stanbury et al., 2003).  Young male manufacturing workers are at high risk of work-related upper limb amputation (Liang et al., 2004). The role of the upper extremities is not limited to physical or functional movements, but, rather, is closely associated with psychosocial roles (Freeland & Psonak, 2007; Hacking, 1997).  Consequently, upper limb amputation is a devastating event and often results in profound physical, psychological and vocational consequences.  Several types of upper limb prostheses are designed to replace the function or appearance of a missing limb as much as possible.  However, upper limb prostheses that are commercially  2 available can only compensate for the loss of fine movements of the hand, tactile sensation, proprioceptive feedback and aesthetic appearance to a limited extent.  Prosthetic terminal devices are not used for fine motor tasks, but rather for supporting, holding and stabilizing actions (Fraser, 1998; Sollermann, 1995).   Prosthetic terminal devices possess one or two degrees of freedom.  Due to the lack of degree of freedoms, the terminal devices are characterized by low grasping functionality which leads to instability of the grasp when external disturbances are applied to the grasped object. Another obvious problem for upper limb amputees who use prosthetic terminal devices is that the amputees are unable to feel what it is that they are holding within the terminal device beyond that which can be visually assessed.  This could be harmful to the amputees in certain situations.  For example, if the amputees were holding a very hot object, the amputees would be unaware and possibly resulting in damage to the prosthetic terminal device or hurting themselves when spilling occurs.  Moreover, the lack of feedback of the terminal devices means that the amputees could be unaware should the object begin to slip.  Therefore, in order to grasp a frangible or slippery object, it is essential for the prosthetic terminal devices to have the ability to detect slip and control signal feedback.  However, currently the Otto Bock SensorHand® is the only commercially available hand prosthesis that is capable of automatically tightening the applied grip force of the hand in the presence of an external perturbation.  This process occurs under an assumption of a constant coefficient of friction between the prosthetic terminal devices and the grasped object (Puchhammer, 2000). Selecting the most appropriate prosthetic components for upper limb amputees is part of the art of upper limb prosthetic rehabilitation.  If individuals feel that prosthetic  3 devices enhance their function and/or appearance, it is more likely that they will use the device.  On the contrary, they will abandon the prosthetic device if the devices are perceived to hinder function, comfort or appearance. Successful rehabilitation in upper limb amputation requires an interdisciplinary approach (Datta & Brain, 1992; Dakpa & Heger, 1997; LeBlanc, 1988; Millstein et al., 1985).  Prosthetic fitting and training is crucial to successful rehabilitation and reintegration of the amputee into a social and work environment.  Thus, it is essential to have a thorough evaluation and take into account each amputee’s functional and psychosocial needs when prescribing a prosthesis for the amputee.  1.2 Research Motivation There are several types of prostheses for individuals with upper limb amputations and each type of prostheses has its own advantages and disadvantages.  In the clinical setting, the most common form of terminal device for body-powered prosthesis is a split hook with canted fingers, whereas the most commonly prescribed terminal device for myoelectric prosthesis is in the form of a myoelectric hand.  The primary and common function between a body-powered hook and a myoelectric hand is to grip an object.  When using terminal devices to grip or manipulate an object, the minimal grip force required to avoid slipping depends on the frictional properties between terminal device and the object. Consequently, the friction between the terminal device and the gripped object play an important role during object manipulation.  However, comparisons of different prosthetic terminal devices have been restricted to characteristics like function, weight, and maximum grip force (Bergman & Ornholmer, 1992; Doshi et al., 1998).  As yet, little is known about  4 frictional properties of the surfaces in contact between different types of terminal devices and the objects being held; thus further studies are warranted. In addition, the process of finding an appropriate prosthesis is complex.  The amputees usually have high expectation and no knowledge of the functions and limitation of the prostheses.  Unrealistic expectation mixed with the psychological trauma can affect amputees asking for something that is not useful, suitable or available.  Studies indicate that upper limb prosthetic devices are not well accepted by the prosthetic users although there are a variety of prosthetic devices to choose from.  The overall rejection rates of body-powered prostheses range from 16% (Bhaskaranand et al., 2003) to 66% (Kruger & Fishman, 1993) and the rejection rate of myoelectric prostheses can be as high as 75% (Crandall & Tomhave, 2002).  Having a protocol that can help in selecting a prosthesis that meets the needs of the amputees may decrease the rejection rates. Adapting to limb loss and gaining employment after the amputations are major challenges for the amputee.  Return to work is considered to be an important aspect of successful rehabilitation.  Moreover, employment of people with an amputation can improve their self-esteem and decrease social isolation (Dougherty, 1999).  It has also been asserted that the ability to return to work is enhanced when appropriate prostheses are used (Datta & Ibottson, 1991; Kyberd et al., 1997).  Therefore, it is crucial to have a protocol that can help prescribe the appropriate prostheses, especially for work, for individuals with upper limb amputations.  Prescription protocol for upper limb prostheses should take into account each amputee’s goals and expectations as well as preferences such as comfort, cosmetic, function, and cost (Sears, 1991).  To the best of our knowledge after an extensive  5 literature search, no standard prescription protocol for upper limb prostheses can be identified.  1.3 Research Objectives In order to obtain an acceptable and useful prosthetic device, understanding the properties of each type of prosthetic terminal device, and assessing the needs of the amputees by having a prescription protocol that can assist in the selection of an appropriate upper limb prosthesis for the amputee are essential.  The primary objective of this study is to propose a standard prescription protocol for upper limb prostheses which will serve as a tool to assist in the selection of a prosthetic device that best fits with the needs of the individual with an upper limb amputation.  This study aims to accomplish the following specific objectives: The properties of prosthetic terminal devices such as function, weight, and maximum grip force are known, but little is known about the frictional properties. Understanding the frictional properties is essential for the grip and slip performance of each type of terminal device.  Therefore, the first and second specific objectives aim to: 1. Examine the frictional properties of the surfaces in contact between the two commonly prescribed terminal devices (i.e., a body-powered split hook and a myoelectric hand) and the gripped objects that made of different types of materials. 2. Examine the effects of loading rates on the frictional properties of the surfaces in contact between the terminal devices and the gripped objects.   6 In order to select the appropriate prosthesis for individual with upper limb amputation, it is important to assess the needs of the amputees and to develop a comprehensive approach by having a standard protocol.  Thus, the third and fourth specific objectives aim to: 3. Propose a standard prescription protocol that can be used as a tool to objectively select appropriate upper limb prostheses based on the needs and conditions of the prosthetic users. 4. Evaluate the effectiveness of the proposed prescription protocol for upper limb prostheses by using retrospective information.  1.4 Thesis Organization This thesis will be organized as follows: In Chapter 2, a review of the literature regarding upper limb amputations and different types of upper limb prostheses will be presented.  Then, comparisons between body-powered and myoelectric prostheses, prostheses acceptance and abandonment, and the return-to-work in upper limb amputations will be discussed.  Followed by this will be a review of the functional range of motion analysis of upper limb and upper limb prostheses, and factors associated with developing a prescription protocol. In Chapter 3, the frictional properties of the surfaces in contact between different types of terminal devices and the objects, as well as the effects of the loading rates on the frictional properties will be examined. In Chapter 4, the standard prescription protocol for upper limb prostheses will be proposed.  The factorial survey approach that is used to develop a scoring system of the  7 proposed prescription protocol as well as the application of the proposed scoring system will be described. In Chapter 5, the effectiveness of the proposed prescription protocol, specifically the scoring system, will be evaluated based on the retrospective information from the selected anonymous patient files provided by the Workers Compensation Board of British Columbia (WorkSafe BC).  WorkSafe BC provided the total of 28 anonymous patient files. However, after reviewing all 28 files thoroughly, only nine cases met the inclusion criteria for evaluation of the proposed scoring system. In Chapter 6, the conclusions and limitations of this study will be discussed. Recommendations for future work will also be presented.  1.5 Expected Contributions from the Current Study  • This study will provide better understanding about the frictional properties of body-powered split hook and myoelectric hand which will contribute to the selection of an appropriate type of terminal device in handling different types of materials and the improvement in design of the terminal device. • This study will provide a standard prescription protocol for upper limb prostheses.  This prescription protocol aims to assess the needs of the individual with upper limb amputation and take into account the amputee’s needs and preferences in order to select a prosthesis that best fit with each individual. • By having a standard prescription protocol that can assist in selecting an appropriate prosthesis, the abandonment rate may be reduced and the prescription of the prosthesis may become more cost-effective.  8     Chapter 2 Literature Review In this chapter, the etiology of upper limb amputation, types of upper limb prostheses and prosthetic components will be presented followed by the comparisons between the body-powered and myoelectric prostheses.  Next, prostheses acceptance and abandonment as well as the return-to-work in upper limb amputations will be discussed. Then, the functional range of motion analysis of upper limb and upper limb prostheses and factors associated with developing a prescription protocol will be reviewed.  2.1 Etiology of Upper Limb Amputation  In 2005, there were about 1.6 million people in the United States living with limb loss, and by the year 2050 the number is projected to reach 3.6 million.  Approximately 8% of all amputations involve upper limb (Ziegler-Graham et al., 2008).  In a study of limb amputations in the United States during the period from 1988 to 1996, it revealed that the most common causes of amputation are vascular conditions (82%), trauma-related (16.4%), cancer (0.9%) and congenital deficiency (0.8%) (Dillingham et al., 2002).  Trauma-related amputations are the majority of upper limb amputations.  The incidence of upper limb  9 traumatic amputations is twice as frequently as lower limb traumatic amputations (Dillingham et al., 2002; Freeland & Psonak, 2007).  Furthermore, of the congenital limb anomalies, the deficiency occurs most commonly within the upper limb population.  On the contrary, in comparison to lower limb amputations, only a small percentage of upper limb amputations are from the effect of tumors or disease (Dillingham et al. 2002).  According to a study by Esquenazi (2004), young, active, and economically productive people are usually affected by traumatic amputations.  Trauma-related was reported to be the leading cause of upper limb amputations in males between the ages of 15-45 (Leonard & Meier, 1993).  Moreover, males are at significantly higher risk for trauma-related amputations than females (Dillingham et al., 2002).  The gender differences in traumatic upper limb amputations are likely attributed to the nature of work-related tasks and recreational activities that males perform (Kyberd et al., 1997).  Upper limb amputations can be classified by the limb segments affected.  The most distal are partial hand amputations.  Wrist disarticulations are amputations that separate the carpal bones from the radius and ulna.  Amputations that occur at the forearm level are classified as trans-radial amputations.  When the radius and ulna are removed but the humerus is preserved, the amputations are designated as elbow disarticulations.  Trans- humeral amputations are those that leave more than 30% of humeral length, whereas shoulder disarticulations are those in which less than 30% of the proximal humerus remains.  The amputations that resect the clavicle and leading to absence of any portion of the thorax or shoulder girdle are referred to as forequarter amputations.  A study by Dillingham et al. (2002) reported that 4.1% of all amputations are trans-radial amputations. The majority of upper limb amputations are trans-radial amputations (57%); compared to  10 23% trans-humeral amputations, 12% wrist disarticulations, and 5% shoulder disarticulations (Atkins et al., 1996).  2.2 Upper Limb Prostheses A prosthesis is a device that is designed to replace the functionality and/or to mimic the appearance of a missing limb or body part as much as possible.  Development of upper limb prosthesis is much more complex than lower limb prosthesis due to its functional complexity and fundamental needs of the upper limb amputees.  Ideally, an upper limb prosthesis should compensate for the loss of fine, coordinated movements of the hand, provide some tactile sensation, and proprioceptive feedback and have an aesthetic appearance (Millstein et al., 1986).  However, all commercial prosthetic devices are still unsuccessful to achieve all these characteristics. Upper limb prostheses can be classified as either passive (cosmetic types) or active (functional types). Active upper limb prostheses are divided into two main control types: body-powered and externally-powered.  The most common commercial externally-powered interface utilizes the electromyogram as a signal and is called myoelectric prostheses.  The following sub-sections will describe different types of prostheses.  2.2.1 Cosmetic Prosthesis Cosmetic prosthesis is a passive device that is worn by amputees who have difficulty operating active prostheses or wear prosthesis for cosmetic reasons.  It cannot be controlled by the  body or electrically.  Cosmetic prostheses have no moving parts and are most generally used only for the sake of appearance.  It is designed to appear very natural,  11 but its fingers are rigid and do not have the ability to perform grasp or release function. However, it can function as an assist to the sound arm in terms of supporting objects or stabilizing items during bimanual tasks and activities (Fraser, 1998; Michael, 1996; Thornby & Krebs, 1992).  This type of prosthesis is generally lighter weight than other prosthetic types due to the absence of operational mechanical components.  Therefore, for amputees who have concerns about the weight of the prostheses and are not in need of a functional grip, a cosmetic hand is a viable option. The finish of cosmetic prosthesis varies widely.  However, many individuals seek out more realistic restorations which require substantially greater investment in financial resources.  2.2.2 Body-Powered Prosthesis A body-powered prosthesis (Figure 2.1) is the type of prosthesis that is usually controlled by gross body movements of the shoulder, upper arm and chest.  This type of prosthesis is suspended and operated via a harness and cable system.  Shoulder flexion or scapular abduction is commonly used to create tension on the cable, which is transmitted to the terminal device and allows it to open or close (Cuccurullo, 2004).  Body-powered upper limb prostheses have the following components: • Suspension and control systems • Terminal devices • Wrist units • Elbow units • Shoulder units  12  Figure 2.1 Body-powered prosthesis  2.2.2.1   Suspension and Control Systems  The socket of an upper limb prosthesis typically has a dual-walled plastic laminate material that is custom molded to the residual limb.  The prosthetic sockets use some type of flexible interface with a rigid frame exterior.  There are several suspension systems used to hold the prosthesis securely to the residual limb which are: harnessing system, self- suspending socket and suction socket.  The harnessing system, which is the foundation of the body-powered prostheses, serves the dual roles of control of the body-powered prosthesis and suspension.  Harnessing materials generally are made of Dacron webbing and a Bowden cable is used for the power transmission system.  The most common harness is the figure-of-eight style harness.  The figure-of-eight harness is formed by means of an axillary loop that is fit over the non-amputated side, a control attachment cable, and an anterior suspension component on the amputated side.  The center of the figure-of-eight should be located below the seventh cervical vertebra and slightly offset toward the sound side for individuals with unilateral amputations (Brenner, 1992).  13 When the amputees are expected to engage in heavy manual labor, particularly the repeated lifting of heavy objects, it is recommended that a shoulder-saddle harness be considered.  With the shoulder-saddle harness, tension loading on the prosthesis is distributed over the shoulder on the amputated side and lessens axilla pressure on the non- amputated side.  However, when a self-suspending socket is recommended, a figure-of nine is indicated.  A figure-of nine harness consists mainly of the contralateral axillary loop leading to the control attachment strap and is used only for control.  Another option is the suction socket which uses a liner made of soft flexible material such as silicone with either a locking or suction valve mechanism.  If suction suspension is used, the harness is used primarily for control. In order to control a prosthetic function, the harness must transmit power from glenohumeral and scapular motion through the cable system to the terminal device and elbow unit, if present.  The control cable systems can be classified as follows: single control, dual control, and triple control (Smith et al., 2004).  For a single-control system, the Bowden cable runs continuously from the harness to the terminal device in order to control the terminal device.  For a dual control system, one cable controls both to flex the prosthetic elbow joint and to operate the terminal device, a second cable controls the locking and unlocking of the prosthetic elbow   The triple control system, which is rarely used, utilizes Bowden cables for each components; one cable controls the elbow joint, a second cable controls the terminal device, and a third cable control the locking and unlocking of the elbow.    14 2.2.2.2   Terminal Devices Terminal devices are common to all upper limb prostheses.  It is the most distal component of the prosthesis that is designed to function in place of the anatomic hand. There are two broad categories of terminal devices for body-powered prostheses: hands or hooks (Billock, 1986; Brenner, 1992).  Hand terminal devices are used for cosmetic appeal; however, hands are heavier, more expensive and more vulnerable to mechanical and chemical damage than are hooks.  Many individuals with upper limb amputations find that hooks provide a higher level of dexterity than prosthetic hands.  This is because the narrower fingers of the hook allow the user to see the objects being manipulated more easily and thus provide more visual feedback.  The most often used functional terminal device for body-powered prostheses is the split hook.  Split hooks have two fingers and are made in various shapes.  The most popular design is the canted design, i.e. the fingers slant toward the midline when the hook is pronated.    Hooks are made from aluminum, stainless steel, and titanium.  Most hooks have a neoprene lining to provide greater friction for a more secure grip (Stark & LeBlanc, 2004). Both hooks and hands may have a voluntary opening or voluntary closing system (Stark & Leblanc, 2004).  However, most terminal devices are classified as voluntary opening.  A voluntary opening terminal device is closed in a rest position.  It enables the amputees to apply tension through the control cable system to open the terminal device against the resistive force of rubber bands (hook) or internal springs (hands).  Relaxing tension on the cable system allows the terminal devices to close around the desired object. The amount of prehensile force is determined by the number of rubber bands or springs used.  On the other hand, voluntary closing terminal devices are not as common.  In a  15 voluntary closing terminal device, the amputees apply tension through the control cable system to close the terminal device from its normally open position (Radocy, 1986).  In order to continue holding the object, one has to maintain tension on the cable.  Relaxing the tension on the cable opens the terminal device.  This has the design advantage of graduated grip force controlled by the amputees, adapting it to the characteristics of the object to be held.  The control movements are more natural and it allows the amputees to grasp with a wide range of prehensile force.  2.2.2.3   Wrist Units Wrist units serve two basic functions which are to provide the attachment of the terminal device to the forearm of the prosthesis and to permit the amputee to preposition the terminal device in pronation or supination.  Pronation and supination are essential for effective orientation of the terminal device.  The wrist unit enables the amputees to rotate the terminal device passively.  Several unit designs are commercially available, including a constant friction unit, a locking unit, a quick disconnect unit and a flexion unit.  Usually the wrist units come in round or oval configuration (Stark & LeBlanc, 2004).  The most common type of wrist unit is a constant friction wrist unit; it provides constant friction throughout the range of motion of the terminal device.  Friction control wrist units are easy to use; however, if the amputees attempt to carry a heavy load, the friction unit may allow inadvertent rotation.  In a locking unit when a lock is engaged, it prevents rotation during grasping and lifting.  Nevertheless, the disadvantage of a locking wrist unit is that the amputees need to unlock and relock the wrist units when a new position is desired.  If more than one terminal device is used, the quick disconnect wrist unit is practical because it is  16 designed to facilitate rapid interchange of different terminal devices.  Another type of wrist unit, a wrist flexion unit provides the amputees with improved function for activities at the midline, such as toileting, shaving, or dressing (Fryer & Michael, 1992).  Figure 2.2 presents the examples of wrist units.   Figure 2.2 Examples of wrist units: (a) friction wrist unit; (b) wrist flexion unit   2.2.2.4   Elbow Units Elbow units are chosen based on the level of the amputation and the amount of residual function.  For medium and long trans-radial amputations, flexible hinges are used whenever forearm pronation and supination can be transmitted to the terminal device (Stark & LeBlanc, 2004).  These hinges may be of leather or metal. Dacron straps may also be used to attach proximally to the triceps pad and distally to the prosthetic forearm. However, flexible hinges do not stabilize the prosthesis.  For short trans-radial amputations, rigid hinges provide additional stability.  Rigid hinges are available in single axis or polycentric versions.  Single axis hinges can be used for the amputees who will be performing heavy manual labor.  In the cases where elbow flexion is restricted by the  17 bunching of the soft tissues in the antecubital fold, a polycentric version is available to help increase elbow flexion by reducing the tendency for bunching of the soft tissues.  A rarely used option for short trans-radial amputations is the step-up hinge.  Step-up hinges amplify the range of motion so that the amputees can achieve the range of motion elbow flexion desired.  Examples of elbow units is shown in Figure 2.3.   Figure 2.3 Examples of elbow units (a) mechanical elbow unit; (b) single axis hinge   Loss of function of the anatomic elbow joint requires a mechanical substitute that allows for 135 degree of flexion and must permit the amputee to lock and unlock the elbow at numerous points throughout range of motion.  Elbow disarticulation usually requires the use of a specially designed elbow unit which is referred to as an outside locking hinge.  For trans-humeral amputations, the standard elbow component is an internal locking elbow unit that incorporates a hinge, lock, and turntable that permits passive internal and external rotation of the humerus.  A spring lift assist is also available.  It is used to counterbalance the weight of the prosthetic forearm and assist in flexion of the elbow.  If insufficient force precludes active function of the elbow unit, a friction elbow unit which requires passive positioning of the forearm may be advantageous  (Fryer & Michael, 1992).  18  2.2.2.5   Shoulder Units  The shoulder disarticulation prostheses adds a shoulder joint as one of the components.  This may be in a monolithic design, passive friction, or active locking device (Stark & LeBlanc, 2004).  A monolithic design is built into the socket and the amputees appreciate the weight saving from omitting the joint.  A passive friction shoulder joint provides some assistance with dressing and positioning for functional activities, whereas an active locking shoulder joint can lock the joint in the desired flexion angle.  2.2.3 Myoelectric Prosthesis Myoelectric prosthesis (Figure 2.4) is the most common externally-powered prosthesis in use today.  Myoelectric prosthesis utilizes electromyographic (EMG) signals, which are signals originating from muscle electrical potential, to control various prosthetic components.  As the amputees voluntary contracts the relevant muscles, surface electrodes embedded in the socket detect the EMG signals produced during the contraction.  Then EMG signals are amplified, filtered, and processed by a programmable electronic circuit. The resulting signal is then sent to the appropriate prosthetic components to generate the desired function (Troncossi, 2007).  Factors influencing the surface electrodes function include: good skin contact, a well-fitting socket, good voluntary muscle control by the amputees, and minimal sweating (Pasquina et. al., 2006). If the amputee only has one reliable myosignal site available, a single-site myoelectric control system may be used.  For the amputee who has good voluntary control of both muscle groups and has isolated muscle contractions, dual-site myoelectric control systems work well.  A typical myoelectric control scheme is to use agonist-antagonist  19 muscles to control opening and closing of the terminal device (Michael, 2004).  The extensor site is typically used to open the terminal device, while the flexors control terminal device closing.  Myoelectric fitting that used a threshold of operation level that required the amputee to contract the given muscle with force above the threshold before the system operated produces a fixed speed of operation, known as digital control.  In this type of control, the terminal device opens and closes at a constant speed, and the amputees can not voluntarily control the speed of operation.  The preferred type of myoelectric control is known as proportional control (Sears & Shaperman, 1991).  Proportional control permits the amputees to vary the speed of operation depending on the strength of the electrical signal input and provides the amputees with the increased precision in grip strength (Sears & Shaperman 1991, 1998).  Moreover, switching between the two different modes (e.g., switch between control of the hand and wrist unit) can be achieved by a quick co- contraction of agonist and antagonist muscles (Pasquina et al., 2006).   Figure 2.4 Myoelectric prosthesis  20 Myoelectric prosthesis components can be classified as follows: • Sockets • Terminal devices • Wrist units • Elbow units • Shoulder units  2.2.3.1 Sockets  Socket materials for upper limb prostheses are made of flexibility thermoplastic polymers.  Flexible thermoplastic polymer socket helps to enhance comfort, increase range of motion, and have more resistance to perspiration (Michael, 2004).  The types of sockets that are most commonly prescribed for myoelectric prostheses are self-suspending sockets (Sauter et al., 1986).  Roll-on silicone sockets have gained acceptance in upper limb myoelectric prostheses over the past ten years (Salam, 1994; Daly, 2000).  This design helps to provide a true suction suspension.  2.2.3.2 Terminal Devices  Prosthetic terminal devices are usually grouped by hands and hooks.  The most commonly used electric terminal device is an electric hand (Heckathorne, 1992).  Most hands are manufactured in an array of sizes and moves in the three-jaw-chuck grasping pattern of the thumb and first two digits (Michael, 2004).  Currently, the only commercially available electric hand prosthesis that adds in a sensor in the finger to detect the slippage of an object is the Otto Bock SensorHand® (Puchhammer, 2000).   The alternative types of  21 electric terminal devices are electric hooks and grippers.  Hooks are not cosmetically attractive; however for some amputees hooks offer excellent functionality.  Recently, bionic hands which are the types of electric terminal devices that can provide the ability of each finger moves independently as well as bend at the finger joints have been introduced (e.g. the i-Limb hand from Touch Bionics, the Otto Bock Michelangelo, and the RSL Steeper bebionic hand (Cipriani et al., 2011)).  However, to date there is no electric terminal device commercially available that replicates the lost of proprioception and sensation of the anatomic hand.  2.2.3.3 Wrist Units A number of wrist units are specially designed for use with electric terminal devices.  Wrist units can be used to position the terminal devices either passively or actively.  For passive wrist units, the amputees must preposition the terminal devices using the contralateral hand or by rotating it against a fixed object.  The wrist units with a quick disconnect feature is common and it is used to facilitate the interchange of terminal devices.  Electric wrist rotation units (Figure 2.5) can be used to allow the amputees to orient the terminal device independently; therefore, keeping the contralateral limb free for other tasks (Sears & Shaperman, 1998).   Figure 2.5 Electric wrist rotation unit  22 2.2.3.4 Elbow Units The two types of elbow units for myoelectric prosthesis are electric and hybrid cable-operated elbow units.  Electric elbow units (Figure 2.6) are appropriate for amputees who do not have sufficient force to operate hybrid cable-operated elbow units.  In a hybrid passive elbow unit, an adjustable friction turntable is used to permit the amputee to manually position the forearm (Wilson Jr., 1998).  On the other hand, a hybrid electrical actuated locks elbow units allows the amputee to control locking functions without harness body movements.   Figure 2.6 Electric elbow unit     2.2.3.5 Shoulder Units The most common shoulder units are friction and locking.  Friction joints are manually positioned and their drawback is that the friction joints can not maintain any flexion or extension securely.  On the other hand, locking units have a positive lock for the desired flexion angle and have two mode of operation: locked and free swing (unlocked) (Sears, 2004)    23 2.3 Body-Powered Prosthesis vs. Myoelectric Prosthesis Body-powered and myoelectric prostheses have their own advantages and disadvantages.  Comparisons between different types of terminal devices are usually based on characteristics like, function, weight, and maximum grip force (Bergman & Ornholmer, 1992; Doshi et al., 1998).  It has been reported that 63% of the amputees indicated that they use a body-powered prosthesis (Atkins et al., 1996).  This may be due to its simplicity, relatively lightweight, low cost, durability, reliability, and functionality (Kruger & Fishman, 1993; Stark & LeBlanc, 2004).  The use of harness and cable systems also provides the amputees better proprioceptive feedback (Lake & Dodson, 2006). Furthermore, a body -powered prosthesis is suitable for heavy work or in environments that include exposure to dirt or liquids (Huang et al., 2001).  It is used in jobs that required heavy lifting, handling sharp material, and exposure to extremes in weather (Millstein et al., 1986). The main drawback of body powered prosthesis is poor cosmetic.  It is also dependent on the amputee’s physical ability to produce sufficient force and body motion to activate prosthetic function (Stark & LeBlanc, 2004).  Another significant disadvantage for a body-powered upper limb prosthesis is that the functional envelope is limited to a relatively small area below the shoulders, above the waist, and not far outward past shoulder width (Brenner, 1992).  Many individuals with upper limb amputations have significant difficulty performing tasks above the head or down near the feet. The major advantages of myoelectric prosthesis include stronger grip force, freedom from harness, graded grip-force, more natural control, and the ability to be used in all planes of arm movement.  Their disadvantages are higher cost, greater weight, greater  24 care and maintenance, less robust, and lack suitability for heavy or dirty work (Dakpa & Heger, 1997).  In 1997, in Canada, the average cost of a below-elbow myoelectric prosthesis was $US 9000 with replacement needed every 4-5 years (Dakpa & Heger, 1997).  A survey of myoelectric prosthetic users showed that 79% repoted that their prosthetic device was too heavy (Pylatiuk et al., 2007).  Prosthesis weight and cost are among the highest priority design concerns.   When compared to myoelectric devices, body powered prostheses are less sensitive to the environmental conditions that may compromise use and require additional maintenance (Brenner & Brenner, 2008).  A study by Kejlaa (1993) found that the myoelectric prosthesis were used by individuals with amputation who are employed in clean and light work environment or undergoing education, while the conventional prosthesis was used by those who worked in heavy duty working conditions.  Moreover, myoelectric prostheses are preferred by amputees where aesthetics are important. Furthermore, a study by Biddiss et al. (2007) reported that priorities for adult electric prosthetic users focus more on functional, sensory feedback, durability and moisture resistance; whereas priorities for body-powered prosthetic users are harness/strap comfort, perspiration control as well as fit and reliability.  Individuals with high level amputations such as shoulder disarticulation and forequarter amputees are good candidates for externally-powered prostheses because externally-powered prostheses requires less energy expenditure than a body-powered prostheses (Dakpa & Heger, 1997).  Moreover, it has been reported that tasks conducted by body-powered prosthesis put a lower mental load on the prosthetic user than the same tasks conducted with an externally-powered prosthesis (Soede, 1982)  25 In addition, a study by Herberts et al. (1980) suggested that a myoelectric prosthesis has a complete absence of sensory feedback and that users must rely entirely on vision for control while a body-powered prosthesis does provide some feedback.  Body-powered prostheses provide more speed and accuracy by enabling the user to sense device actuation through cable tension and harness position.  Scott and Parker (1998) asserted that sensory feedback of the myoelectric prostheses is limited to visual and auditory cues from the sound of the motor.   Although myoelectric prostheses do not provide the tactile feedback that body- powered prosthetic devices do, they do provide more proximal function for upper humeral amputation patients and also produces greater grip strength (Light et al., 2002).  Nevertheless, some studies have reported that approximately 33% of the amputees thought that the myoelectric prosthetic device provides better feedback than the body- powered prosthesis (Kritter, 1985; Silcox et al., 1993).  2.4. Prosthetic Acceptance and Abandonment  Upper limb prostheses are not well accepted by the amputees.  The most obvious reason for prosthetic rejection is failure to satisfy the needs of the prosthetic users.  One of the limitations is the lack of sensory feedback available to the user, inhibiting the ability to respond in an appropriate manner to the external environment (Jones, 1997; Riso, 1999). However, some researchers have argued that prosthetic acceptance depends on the early fitting of the prostheses (Day et al., 1969; Jacobs & Brady, 1975), intensive training (Bailey, 1970), and psychological effects (Friedmann, 1978).  Leonard et al. (1989) asserted that early prosthetic fitting not only would improve the acceptance and used of prosthesis but also the return to prior functional level.   Other studies also suggested that  26 early fitting establishes an acceptance of and tolerance for the prosthesis.  Early fitting also encourages bilateral movement patterns and promotes better use and skill development (Angliss, 1974; Kejlaa, 1993).  In addition, some studies found successful prosthetic use was associated with loss of the dominant hand (Datta & Ibottson, 1991; Datta et al., 1989; Wright et al., 1995) while others found no such association (Gaine et al., 1997; Kyberd et al., 1998; Roeschlein et al., 1989; Silcox et al., 1993). Overall rejection rates of body-powered prostheses vary from 16% (Bhaskaranand et al., 2003) to 66% (Kruger & Fishman, 1993).  The common complaints include harness discomfort, unnatural appearance, excessive wear temperatures, abrasion of clothes, and wire failure (Kejlaa, 1993; Bhaskaranand et al., 2003; Dudkiewicz et al., 2004).  The rejection rates of body-powered hands can be as high as 87% (Kejlaa, 1993).  The main factors for the rejection of the body-powered hands are the heavy weight, insufficient grip strength, high-energy expenditure to operate, restricted functionality, and difficulty in maintenance (Millstein et al., 1986; Kejlaa, 1993).  On the other hand, body-powered hooks are more acceptable to users due to their functionality, durability, lower weight and good visual feedback (Millstein et al., 1986). Myoelectric prostheses rejection rates can be as high as 75% (Crandall & Tomhave, 2002).  The main factors affecting myoelectric prosthetic rejection and abandonment include the excessive weight, excessive wear temperature (Ballance et al., 1989; Kejlaa, 1993), and durability, especially for pediatric population (Datta et al., 1989; Herberts et al., 1980; Hubbard et al., 1997; Northmore-Ball et al., 1980).  The prevalence of weight-related complaints ranges from 13% (Datta et al., 1989) to 81% (Hubbard et al., 1997).  Surveys  27 reveal that more than 30% of the externally-powered prosthetic hand users do not use their prostheses regularly (Arkins et al., 1996; Silcox et al., 1993). A study by Atkins et al. (1996) asked prosthetic users to rank desired improvements of the prostheses.  They reported that, for body-powered prosthetic users, the order of importance was: function, comfort, and cosmetics.  For electric prostheses users, the order of importance was: function, cosmetics, and comfort.  Another study by Schultz et al. (2007) found that, from the prosthetic professionals’ opinion, comfort was considered the most important factor for unilateral amputees and socket-interface comfort was considered more important than weight.  For bilateral amputees, on the other hand, function was considered the most important factor and agility was considered more important than power. Both body-powered and externally-powered prostheses, if worn, tend to be extensively used for social activities and at work/school (Datta et al., 1989; Hubbard et al., 1997; Kejlaa, 1993; Millstein et al., 1986; Northmore-Ball et al., 1980; Silcox et al., 1993; Weaver et al., 1988). With regard to the level of amputation, some studies found no correlation between the prosthetic acceptance and level of amputation (Roeschlein & Donholdt, 1989; Kyberd et al., 1998), while other studies reported that prosthetic acceptance rates are related to the level of amputation.  Studies found that acceptance of prostheses by individuals with trans-radial amputation are considerably higher than acceptance by those with trans-humeral amputation (Datta & Ibottson, 1991; Datta et al., 1989; Davidson, 2002; Roeschlein & Domholdt, 1989; Stein & Walley, 1983). A study by Millstein et al. (1986) reported that, among trans-radial amputees, the acceptance rate for the body-powered prostheses was 69%, and for electrical prostheses it  28 was 82%.  In individuals with trans-humeral amputation, the acceptance rates were 73% and 86% for the body-powered prostheses and electrical prostheses, respectively. In their study, patients found that prosthesis is essential for personal and employment activities.  It also indicated that the amputees used more than one prosthesis in order to achieve their functional needs.  2.5 Return-to-Work after Amputation Generally individuals with upper limb amputation return to jobs that are less physical demanding, but required greater intellectual ability (Millstein et al., 1985).  Time from amputation to the first prosthetic fitting is important.  If it is too long the amputees are less likely to be able to return to work (Gaine et al., 1997).  A study by Malone et al. (1984) reported that the rehabilitation success rate for amputees who fit with a prosthesis within 30 days of amputation was 93% and the return-to-work rate was 100% within 4 months of injury.  By contrast, individuals fit with a prosthesis beyond the 30 day window exhibited a 42% rehabilitation success rate with a 15% return-to-work rate within 6 to 24 months. Studies also found that for people with finger or partial hand amputation the re- employment rate varies from 64% (Sagiv et al., 2002) to 72.2% (Burger et al., 2007). Whether a person following upper limb amputation will still be able to maintain the same job depends on several factors such as the type of work and the level of amputation. A study by Millstein et al. (1985) revealed that most amputees returned to employment. Moreover, individuals who frequently use prostheses are more likely to be employed.  Prior to amputation, the occupations that the amputees were employed included machining, processing, product fabrication, and construction.  After amputation, the occupations were  29 predominately in service, clerical, sales, and managerial positions.  Post amputation, only 7% returned to a heavy job while 16% secured a sedentary job.  The findings also suggested that about 75% of employed amputees returned to a job that was less heavy than their job prior to the accident.  Several studies also reported that the amputees who had unskilled manual work are the majority of those who had to change their jobs after amputation (Burger et al., 2007; Davidson, 2002; Jones & Davidson, 1995; Millstein et al., 1985).  Most of them changed their jobs to clerical work, services, or went back to study (Davidson, 2002; Jones & Davidson, 1995; Millstein et al., 1985).  It has also been reported that the unemployment rate is lowest for people with trans-radial amputation, followed by partial hand amputation and trans-humeral amputation (Millstein et al., 1985). Studies have shown an association with the use of a myoelectric prosthesis and the type of occupation.  Persons who work at a desk or perform light activities are more likely to accept a myoelectric prosthesis than ones who is engaged in manual labor (Northmore- Ball et al., 1980; Silcox et al., 1993).  In addition, studies found that the dominance of the hand does not influence return to work (Burger et al., 2007; Millstein et al., 1985) and has no influence on the type of work after amputation (Burger et al., 2007).  It has also been reported that the amputees younger than 50 years of age are more likely to return to work than the older amputees (Wright et al., 1995) and the amputees older at the time of amputation are less successful in their return to work (Millstein et al., 1985).  With regards to gender, a study found that women are more likely to be able to return to the same job as before partial hand amputation than men (Burger et al., 2007); whereas other studies found that women are less likely to return to work than men (Millstein et al., 1985; Wright et al., 1995).  30 2.6 Functional Range of Motion Analysis The functional capacity of the upper limb consists of multiple spheres of action that are determined by the shoulder complex, elbow, wrist, and hand (Sarrafian, 2004).  Upper limb movements are complex and cannot be described easily.  Therefore, prescribing appropriate intervention for the patient is of challenges for healthcare professionals. Several studies looked at functional tasks like activities of daily living (ADL) in a normal population which is an area of importance to the persons with upper-limb disabilities. A study by Morrey et al., (1981) recorded the amount of normal elbow motion required for 15 ADLs.  The results showed that the amount of elbow motion required to perform selected ADLs, such as opening a door, drinking, and using a telephone, ranged from 20-135 degrees of elbow flexion.  Most activities were performed with the forearm rotation ranged from 10 degrees of pronation to 50 degrees of supination.  Another study by Brumfield and Champoux (1983) quantified the range of wrist motion required to perform 15 ADLs.  These selected activities included many of the same activities as in Morrey et al. (1981) study.  This study found that the optimum amount of wrist motion required to accomplish most activities ranged from 10 degrees of flexion to 35 degrees of extension.  A more recent study by Ryu et al. (1991) analyzed functional range of motion of the wrist required to perform ADLs.  The results showed that all of the ADL tasks that were analyzed could be achieved with 52 degrees of flexion, 60 degrees of extension, 17 degrees of radial deviation, and 42 degrees of ulnar deviation. In a study by Magermans et al., (2005), the shoulder and elbow motions while performing eight range-of-motion tasks and five ADLs were analyzed.  The results indicated that to comb their hair subjects used at least 73 degrees of glenohumeral elevation  31 and 112 degrees of elbow flexion.  In perineal care, the most important angle in performing this task was internal rotation with the minimum of 71 degrees. In the eating task, the most important joint angle found for performing this task was elbow flexion of approximately 117 degrees.  Among the selected activities evaluated in this study, the reaching task required the highest glenohumeral elevation and pronation. For individual with upper limb amputation, the range of motion is loss and thus the ability to perform ADL also diminishes.  There are a number of restrictions that directly affect the range of motion in person with upper limb amputation.  In a study by Miguelez et al. (2003), the range of motion in three different types of self-suspending socket designs and normal range of motion of the elbow were compared.  The results show that the normal elbow motion had a functional arc of flexion of 146 degrees.  The functional arc of flexion was reduced to 78 degrees, 86 degrees, and 100 degrees with the use of Muenster socket Northwestern socket, and transradial anatomically contoured socket, respectively.  Another study by Daly (2000) reported that there was increased elbow range of motion from 15-27 degrees in the use of silicone roll-on liner, compare to the use of supracondylar suspension mechanisms. Comparisons of the functional effectiveness between body-powered prostheses and myoelectric prostheses were made in several studies (Stein & Walley, 1983; Weaver et al., 1988).  In a study by Stein and Walley (1983), the amputees were asked to operate terminal devices in five different positions: above shoulder level, at the mouth, behind the neck, behind the back, and in front of the body.  Moreover, the amputees were asked to perform a number of tasks with their normal arm and with their prosthesis for comparison.  The findings show that the body-powered prosthetic users had most difficulty operating the  32 terminal device behind their back and behind their neck.  On average, the amputees with myoelectric prostheses scored higher in the tests of functional range of motion than those with body-powered prostheses.  In addition, it was found that myoelectric prosthetic users were able to carry out the tasks in a more normal position, comparing to body-powered protsthetic users. Weaver et al. (1988) reported that with the use of myoelectric prosthesis the amputees felt they could grasp and hold objects more securely.  It was also found that the rate of performance in bimanual activities with the myoelectric prosthesis increased by 61.7% in the dressing task, 50% in hygiene, 51.8%  in eating, 55.77% in tasks about the home, 79.48% in school and work activities, and 70.58% in play activities.  It was asserted that the increased in the rate of performance was due to the freedom from harnessing in myoelectric prosthesis.  2.7 Prosthetic Prescription A wide variety of prosthetic components available on the market makes prosthetic prescribing a complicated process (Roberts et al., 2006).  An appropriate prosthesis not only is associated with the acceptance and usefulness of the prosthesis, but also may protect the contralateral limb from extra stresses related to overuse (Lake & Miguelez, 2003).  In selecting the optimum prosthesis for individual with upper limb amputation, many factors must be considered and a comprehensive evaluation is required.  The prosthetic comprehensive evaluation should begin with gathering the history and general information of the amputee, including general demographic data, economic considerations, hand dominance, the cause and date of amputation, associated diseases and injuries,  33 medications, and previous prosthesis use.  The evaluation process should also assess the functional status and the psychosocial status which includes emotional adaptation, motivation, living situation, family and social support systems.  Furthermore, the information regarding the amputee’s prior vocational and leisure interests as well as the future plans should also be recorded.  It is also important to determine the amputee’s goals and expectations regarding the prosthesis (May, 2002; Meier, 2004). Furthermore, the physical assessment should be conducted.  The condition of the residual limb, such as the presence of pain, the length and shape of the residual bone, skin condition, muscle strength and range of motion also plays a role in the prosthetic prescription The sensory testing should also be performed.  In addition, the presence or absence of pain and detailed description of residual limb pain, phantom sensation and phantom pain should be documented (May, 2002; Meier, 2004).  Residual limb pain is defined as pain in the remaining part of the amputated limb. The prevalence rates of residual limb pain in individuals with limb loss vary from 12% to 71% (Loeser, 1990). Studies suggest that residual limb pain is intermittent and episodic in nature and is typically in the range of mild to moderate intensity on a numerical rating scale (Ehde et al. 2000; Smith et al., 1999). Most individuals with limb loss report the presence of a perceived phantom limb.  It is more likely that the phantom sensation would occur in the dominant extremity than the nondominant.  This may be because of more elaborate neural interconnections (Livingston, 1945).  These sensations may include such feelings as tingling, numbness, tickling, and itching (Wilkins et al., 1998).  Phantom limb pain refers to painful sensations in the absent portion of the amputated limb (Davis, 1993).  The prevalence rates of phantom limb pain in  34 individuals with amputations can be as high as 85% (Ehde et al, 2000).  However, it should be noted that most studies have been conducted on samples comprised of individuals with lower limb amputations because the upper limb amputation is less common.  Recent studies have found the rates of phantom limb pain of 41% (Dijkstra et al., 2002) and 51% (Kooijman et al., 2000) in individuals with upper limb amputations.   Several studies suggest that phantom limb pain is intermittent and episodic in nature (Iacono et al., 1987; Kooijman et al., 2000) and average pain intensity on a numerical rating scale across studies generally classified as moderate (Jensen et al., 2001). Amputations generally result in one of three shapes to the residual limb: cylindrical, conical or bulbous (Smith, 2003).  The length of the residual limb determines the length of the lever arm that will be use to operate the prosthesis.  Descriptions of the scar and its placement, and edema should be recorded.  Scar can be classified into healed, adherent, invaginated, and flat (May, 2002).  There are a variety of methods to measure edema, such as circumference measurement and assessment of the presence of pitting and the recovery time for the skin to return to its original state; the edema score ranging from 0 to 4 (Seidel et al., 1995).  In addition, for myoelectric control, it is important to evaluate for possible sites of electrodes placement and electromyographic signal strength (Sears, 1991).  These skin conditions influence the prosthetic fitting.  Moreover, the muscle strength and range of motion measurements must be performed in order to examine whether there are any limitations that can affect the prosthetic function and to make the prosthetic prescription that is most appropriate for the amputee.  It should also be pointed out that the measurements of muscle strength and range of motion of the sound limb is also important (Meier, 2004).  Moreover, when prescribing a prostheses, patient preferences, comfort,  35 cosmetic, function, reliability, and cost should also be taken into consideration (Schaffalitzky et al., 2009; Sears, 1991).  2.8 Summary In summary, upper limb prostheses can be classified as passive or active types. Active upper limb prostheses are body-powered or externally-powered prostheses.  The most popular type of externally-powered prostheses is myoelectric prosthesis.  Both body- powered and myoelectric prostheses consist of several prosthetic components.  The most common terminal device for body-powered prosthesis is the split hook; whereas that for myoelectric prosthesis is the myoelectric hand.  Each type of prostheses has its pros and cons.  For body-powered prosthesis, the advantages include its lightweight, low cost, durability, and reliability; whereas the main drawback is poor aesthetic.  Myoelectric prosthesis, on the other hand, provides high grip force, freedom from harness, and the ability to perform in all planes of movement, but its downside is associated with cost and weight.  Furthermore, body-powered prostheses generally are used in the heavy-duty work conditions while myoelectric prostheses are used in the clean and light work. In general upper limb prostheses are not well accepted by the amputees.  Prosthesis acceptance and rejection is a complex issue.  Several factors such as type of work, level of amputation, age and gender also influence the return to work.  It is also been asserted that the upper limb amputees should be fitted with a prosthesis as soon as possible. From the literature review, as yet there is no standard prosthetic prescription protocol for upper limb prostheses.  Selecting an appropriate type of prosthesis for an individual with upper limb amputation is a complex process.  It needs a thorough evaluation and follow up by a  36 multidisciplinary team.  Prosthetic prescription for upper limb prostheses should be tailored to help meet each amputee’s performance expectations.  Functional and vocational goals, physical condition, psychosocial status, expected environmental exposures, health insurance coverage, assess to prosthetic maintenance, and patient preferences should be taken into account when considering such a prescription. The amputee’s needs, quality of life, as well as return to work are important components that need to be addressed for prosthesis success.       37     Chapter 3 Frictional Properties of Terminal Devices  An upper limb prosthetic device is designed to replace a missing upper limb.  Upper limb prostheses can be either passive or active.  Passive prostheses are generally used for aesthetic reasons.  The two main categories of active prostheses are body-powered and externally-powered prostheses.  A myoelectric prosthesis is the most common externally- powered prostheses.  A terminal device is the most distal component of the upper limb prosthesis that is designed to substitute the hand function for individuals with upper limb amputations.    However, prosthetic terminal devices that are available on the market are still unsuccessful to match all human hand characteristics.  From the literature review in Chapter 2, the most commonly prescribed terminal device for body-powered prostheses is a split hook with canted fingers whereas the most common form of terminal device for myoelectric prostheses is in the form of a myoelectric hand. The primary function of terminal device is to provide the ability to grip and manipulate objects.  However, one of the apparent problems associated with the use of prosthetic terminal devices is the lack of feedback which means that the amputees could be unaware should the object begin to slip.  When gripping or manipulating an object, the  38 minimal grip force required to avoid slipping depends on the frictional properties between terminal device and the object.  Therefore, the friction between the terminal device and the gripped object play a critical role during object manipulation.  Comparisons of different prosthetic terminal devices have been limited to characteristics like function, weight, and maximum grip force (Bergman & Ornholmer, 1992; Doshi et al., 1998).  However, little is known about the frictional properties of the surfaces in contact between different types of terminal devices and the gripped objects.    Because objects that are gripped or manipulated on a daily basis come in various types of materials, sizes, and shapes, it is important to understand the frictional properties between the contact surfaces of terminal devices and various types of objects.  Understanding more about the frictional properties of terminal devices may assist in the selection of an appropriate type of terminal device when handling different types of objects. Therefore, in this chapter, the frictional properties of the surfaces in contact between two types of terminal devices (i.e. a body-powered hook and a myoelectric hand) and the gripped objects will be examined.  The principles of friction, stick-slip motion, and the effect of loading rate on frictional properties will be reviewed first.  This will be followed by the slip measurements of terminal devices and the frictional properties of terminal devices.  3.1 Friction 3.1.1 Principles of Friction Friction is defined as the force that opposes the motion of two objects in relative motion by interaction of the surfaces in contact.  Leonardo da Vinci was the first to  39 discover two laws of friction in the 15th century (Sarkar, 1980).  These classic laws of friction were later introduced by Guillaume Amontons in 1699, which state as follows: 1. The friction force is directly proportional to the applied normal load. (Amontons’ 1st law) 2. The friction force is independent of the apparent area of contact. (Amontons’ 2nd law) The third empirical law of friction which was enunciated in 1780 by Charles Augustin Coulomb states the following: 3. Kinetic friction is independent of the sliding velocity. (Coulomb’s law of friction) Following these basic laws of friction, Coulomb engraved a frictional model which is commonly used today to evaluate friction force known as Coulomb’s friction model. The Coulomb’s friction model states that the tangential force of friction is proportional to the applied normal force, and the constant of proportionality is a function of the materials which are in contact.  This model can be formulated as follows: Ncf FF µ=                                                         (3.1) where  fF  is the Coulomb’s tangential friction force;  cµ  is the Coulomb’s coefficient of friction; and  NF  is the normal force.  40 Friction can be divided into two regimes which are the static friction and the dynamic friction.  Static friction is the friction when there is no slipping between the two surfaces of the contact.  The force needed to initiate gross sliding is the maximum static friction force.  The static friction formula is as follows: NSS FF µ=                                                         (3.2) where  SF  is the static tangential friction force; and  Sµ  is the static friction coefficient.  The kinetic friction force ( KF ) is the force that sliding surfaces exert on each other after the force of static friction has been overcome.  It is independent from sliding velocity.  The coefficient of kinetic friction ( Kµ ) is defined as the ratio of the kinetic friction force ( KF ) to the normal force ( NF ).  For the same materials, the static friction coefficient ( Sµ ) is usually larger than the kinetic one ( Kµ ).  Friction depends on a variety of factors including the materials of both the terminal device and the object being gripped, roughness of the surface, shape, hardness, elasticity, temperature, humidity, surfaces (e.g. oily, wet, slippery, soapy), contact area, and angle.    41 3.1.2 Stick-Slip Motion Stick-slip motion is a typical behavior for a system with friction.  It is a phenomenon that is generally caused by the fact that the static friction coefficient ( Sµ ) is usually larger than the coefficient of kinetic friction ( Kµ ).  As its name indicates, it is a spontaneous jerking motion that occurs when two objects are sliding over each other.  A typical experimental set up that may demonstrate stick-slip motion is shown in Figure 3.1.  Figure 3.1 Typical experimental setup for stick-slip motion  In Figure 3.1, a unit mass (m) is attached to a spring and the end of the spring is pulled with a constant velocity (v).  The sliding friction has a static friction component. Once the static friction is surpassed, the mass begins to slide and the friction coefficient decreases rapidly from its static value to its dynamic values.  Then, the spring contracts and the spring force decreases.  At this point the mass will slow down until it comes to rest. Then, the phenomenon repeats itself.  The role of the spring is to translate the displacement of the spring into a force by virtue of Hooke’s law.  Hooke’s law states that  kxF −=                                   (3.3)    42 where  F is the restoring force of a spring;  k is a constant called the spring constant; and x is the displacement of the spring.  Figure 3.2 illustrated the tangential friction force versus time of a typical stick-slip cycle.  The amount of force required to overcome static friction in the stick-slip motion is defined as the break-away force.  The static friction coefficient ( Sµ ) is defined as the ratio of the tangential friction force at slip to the constant normal force.   Figure 3.2 Tangential friction force versus time of a typical stick-slip cycle  3.1.3 Effect of Loading Rate Several studies have investigated the effect of the rate of application of the tangential force on the static friction coefficient ( Sµ ).  A study by Campbell (1939) found that, for slowly applied loads, static friction coefficient ( Sµ ) is considerably independent  43 of the loading rate.  Another study by Parker et al. (1950) also reported that the coefficient of static friction was insensitive to tangential load rate.  However, the findings from more recent studies by Johannes et al. (1973) and Richardson and Nolle (1976) indicated that the static friction coefficient ( Sµ ) was sensitive to the rate of application of the tangential load.  They found that the static friction coefficient ( Sµ ) decreased in an exponential manner with increasing loading rate and eventually reached a constant value.  They quantified the loading rates in terms of a tangential load rate coefficient (θ&  ) which is defined by NF F& & =θ                                  (3.3) where  F&  is the rate of application of the tangential load.  Note that the rate of application of the tangential load ( F& ) is directly proportional to the spring constant (k) and the velocity of the moving surface (v).  3.2 Slip Measurements of Terminal Devices 3.2.1 Parameters 3.2.1.1 Types of Terminal Devices In the clinical setting, the most commonly prescribed terminal devices for body- powered prosthesis and myoelectric prosthesis are the split hook and the myoelectric hand, respectively.  Thus, it is of interest to examine the frictional properties of the two selected  44 types of terminal devices which are the body-powered split hook and the Otto Bock Myohand DMC VariPlus Speed®. The Otto Bock Myohand DMC VariPlus Speed® is selected for this study because it is commonly prescribed to the amputees and Otto Bock is one of the leading companies in myoelectric prostheses in North America.   3.2.1.2 Types of Materials  The terminal devices are used for gripping and handling objects.  Objects that are gripped and manipulated on daily basis are made of different types of materials such as metal, plastic, and wood.  Thus, three types of materials which are metal, plastic, and wood were selected for this study.  Each object is in rectangular shape with a thickness of 0.8 mm.  The surface roughness and hardness of all the objects being tested in this study are kept constant.  3.2.1.3 Loading Rates  Some studies have reported that the static friction coefficient ( Sµ ) is dependent on the loading rate, while other studies reported that it is independent of the loading rate. Therefore, it is of interest to investigate the effect of loading rate on the static friction coefficients ( Sµ ) of the contact surfaces between the terminal devices and the gripped objects.  The loading rates used in this study are arbitrary chosen to be at 0.05 N/s, 0.5 N/s, and 5 N/s.  These loading rates are typically presented in the terms of load rate coefficients with the unit  s-1.  These result in the load rate coefficients 0.004 s-1,0.037 s-1, and 0.369 s-1, respectively.  The range of the chosen loading rates are estimated to be about the loading rates when pouring water into a glass. These loading rates will be referred to as the low, medium, and high loading rates, respectively.  45 To evaluate the frictional properties of the contact materials between the terminal devices and the gripped objects, the static friction coefficients ( Sµ ) of the surfaces in contact between the terminal devices and the gripped objects were examined.  It is possible to calculate the static friction coefficient ( Sµ ) from the tangential friction force ( SF ) when slippage occurs at a fixed normal force ( NF ) as in the equation 3.2.  Therefore, the normal force ( NF ) that both types of terminal devices (i.e. body-powered split hook and Otto Bock Myohand DMC VariPlus Speed®) exerted on the gripped objects was constant throughout the entire experiments in this study.  The constant normal force ( NF ) in this study was chosen to be equal to the amount of force exerted from three rubber bands which is the amount of rubber bands that individuals with upper limb amputation are commonly used when operating the body-powered hook.  The procedure in measuring the amount of normal force ( NF ) will be described in section 3.2.3. 3.2.2 Apparatus 3.2.2.1 Body-Powered Split Hook For body-powered prosthesis, the most often used functional terminal device is the split hook (Figure 3.3).  It provides lateral gripping and precise manipulation at the tip. The most popular designs are canted to one side to provide better visual feedback.  The term “canted” refers to the slanted configuration of the hook fingertips, which facilitates visual inspection during fine motor tasks.  It has the neoprene lining to provide greater friction coefficient and better grasp.  It can be opened or closed via a cable.   Prehensile forces can be generated by using multiple layers of rubber bands but must be matched with the user’s ability to create and sustain cable excursion.  Because grip strength is determined  46 by the number of rubber bands used, it is constant and cannot be voluntarily modified. One rubber band can provide approximately 1 pound (4.45 N) of pinch force.    Figure 3.3 Body-powered split hook   3.2.2.2 Otto Bock Myohand DMC VariPlus Speed ® The most commonly used terminal device of myoelectric prostheses is a myoelectric hand.  In this study, the myoelectric hand that is selected to be used is the Otto Bock Myohand DMC VariPlus Speed® (Figure 3.4).  The Otto Bock Myohand DMC VariPlus Speed® use a three-jaw-chuck grasping pattern of the thumb and first 2 digits which gives the user a reasonable blend of function and appearance.  The remaining fingers follow passively but in a similar pattern to the active first two digits opposing the thumb. In myoelectric prostheses, the grip strength is achieved from an input signal generated by muscle contraction.  An inner shell covered by a polyvinylchloride (PVC) glove protects the electronic system within the hand.   47  Figure 3.4 Otto Bock Myohand DMC VariPlus Speed ®  3.2.2.3 Instron DynaMight The tangential frictional force ( SF ) was measured by the Instron DynaMight (Figure 3.5) (Instron Corporation, Norwood, MA).  The Instron DynaMight is a servo- hydraulic axial testing system which has a built-in load cell.  The system has a force capacity of ± 1 kN and the actuator stroke of ±25 mm.  The force accuracy is ± 0.01 N and the displacement accuracy is ± 1µm.    Figure 3.5 Instron DynaMight  48  3.2.2.4 FlexiForce® Sensor  The FlexiForce® sensor (Figure 3.6) (Tekscan, South Boston, USA) was used to measure the normal force ( NF ) that each terminal device applied on the gripped objects. This sensor acts as a force sensing resistor.  The active sensing area is 0.375 inches in diameter.  The application of a force to the active sensing area of the sensor results in a change in the resistance of the sensing element in inverse proportion to the force applied. The resistance can be read by connecting a multimeter to the outer two pins of the FlexiForce® sensor.  The FlexiForce® sensor is capable of measuring up to 100 lb (444.82 N). with ± 3 % accuracy.  Figure 3.6 FlexiForce ®  sensor  The FlexiForce® sensor is needed to be calibrated before using it for the first time. In this study, the calibration procedures were as follows: 1.  Connect the FlexiForce® sensor to a multimeter (Fluke 77 Series II Multimeter; Fluke Corporation, WA, USA; 3.2 MΩ range with ± (0.5% +1) accuracy).  Note that the multimeter used in this study was calibrated by using two multimeters for the measurements.  Then the results from the two multimeters were compared to see whether the measured values are the same. 2.   Apply known forces, using dead weights range from 10-250 N to the sensor.  49 3.  Equate the sensor resistance output as read from the multimeter to the known force applied. 4. Plot force versus conductance (1/resistance) curve.  Figure 3.7 shows the conductance curve for FlexiForce® sensor calibration used in this study.  This conductance curve is used to determine the amount of force that corresponds to the sensor resistance output.  Figure 3.7 Conductance curve for FlexiForce ®  sensor calibration (The error bars indicate standard deviation)   3.2.2.5 Spring  In order to evaluate the frictional properties of the surfaces in contact between the terminal devices and the gripped objects, a spring was used to connect between the object to be gripped and the Instron DynaMight’s load cell.  To be able to apply the desired  50 loading rate, the spring’s constant (k) (i.e. the constant that converts the elongation of the spring to the force by virtue of Hooke’s law) was needed to be determined. To determine the spring’s constant (k), one end of the spring was fixed to the Instron DynaMight’s load cell and the other end to a fixed object, then set the speed of the actuator to an arbitrary value.  The force F(t) and position x(t) were obtained.   Figure 3.8 shows the force versus time (blue curve) and position versus time (green line) of the spring’s constant characterization.  Figure 3.8 Spring’s constant characterization  As shown in Figure 3.8, the spring’s linear range is between t0 = 6s and t1 = 29s. The corresponding position samples x(t0) and x(t1) can be read on the green line.  One can infer the spring’s constant using the relation:  51 )()( )()( 01 01 txtx tFtF k − − =                                              (3.4)  3.2.3. Procedures  3.2.3.1 Normal Force ( NF ) Measurement for Body-Powered Split hook  1.   Put three rubber bands at the based of the body-powered split hook. 2. Attach the FlexiForce® sensor to the contact surface of the body-powered split hook and connect the sensor to the Fluke 77 Series II Multimeter. 3. Use the body-powered split hook to grip an object. 4. Then, record the sensor resistance output as read from the multimeter. 5. Repeat this step 5 times. 6. Determine the pinch force or normal force ( NF ) from the conductance curve in Figure 3.7. The force applied to the active sensing area of the FlexiForce® sensor resulted in a change in the resistance of the sensing element which is in inverse proportion to the force applied.   From the measurements, the average pinch force or normal force ( NF ) of three rubber bands was equal to 13.56 N.  This normal force ( NF ) was used as a fixed normal  52 force ( NF ) in all slip measurements in this study in order to examine the frictional properties of the materials in contact between the terminal devices and the gripped objects. 3.2.3.2 Normal Force ( NF ) Setting for Otto Bock Myohand DMC VariPlus Speed ® 1. Attach the FlexiForce® sensor to the palmar surface of the thumb of the myoelectric hand and connect the sensor to the Fluke 77 Series II Multimeter. (Figure 3.9).  Figure 3.9 Normal force setting for Otto Bock Myohand DMC VariPlus Speed ® 2. Use the Otto Bock MyoSimulator to apply electrical signals to control the Otto Bock Myohand DMC VariPlus Speed® to grip the object (Figure 3.9).  Adjust the electrical signals from the Myosimulator to apply a constant pinch force or normal force ( NF ) at 13.56 N.  53 3. Set the electrical signal from the Myosimulator to be constant and equal to normal force ( NF ) at = 13.56 N for all the slip measurements in order to examine the frictional properties of the materials in contact between the myoelectric hand and the gripped objects. 3.2.3.3 Examining the Frictional Properties of the Materials in Contact between Body-Powered Split Hook and the Gripped Objects 1. Calibrate the Instron DynaMight. 2. Fix the body-powered prosthesis on a lab stand (Figure 3.10).  Use the body- powered split hook with three rubber bands (i.e. apply a constant normal force ( NF ) = 13.56 N) to grip an object. 3. Use the spring to connect between the object to be gripped by the split hook and the load cell of the Instron DynaMight. 4. Apply a constant loading rate of 0.05 N/s by the motor of the Instron DynaMight to pull the gripped object. 5. Measure the tangential friction force ( SF ) when the slippage occurs by the Instron DynaMight’s load cell. 6. Repeat step 4 – 5 for five times. 7. Repeat step 4 – 6 at the medium (0.5 N/s) and high (5 N/s) loading rates. 8. Perform step 1 – 7 for the objects made of metal, plastic and wood.   54  Figure 3.10 Experimental set up for body-powered split hook  3.2.3.4 Examining the Frictional Properties of the Materials in Contact between Otto Bock Myohand DMC VariPlus Speed ®  and the Gripped Objects 1.   Calibrate the Instron DynaMight. 2. Fix the Otto Bock Myohand DMC VariPlus Speed® on a lab stand (Figure 3.11). 3. Apply the electrical signal from the Myosimulator that has been set to a constant normal force ( NF ) of 13.56 N to control the myoelectric hand (from section 3.2.3.2) to grip an object. 4. Use the spring to connect between the object to be gripped by the myoelectric hand and the load cell of the Instron DynaMight.  55 5. Apply a constant loading rate of 0.05 N/s by the motor of the Instron DynaMight to pull the gripped object. 6. Measure the tangential friction force ( SF ) when the slippage occurs by the Instron DynaMight’s load cell. 7. Repeat step 5 – 6 for five times. 8. Repeat step 5 – 7 at the medium (0.5 N/s) and high (5 N/s) loading rates. 9. Perform step 1 – 8 for the objects made of metal, plastic and wood.  Figure 3.11 Experimental set up for Otto Bock Myohand DMC VariPlus Speed ®    It is important to note that the mechanical stability of both terminal devices was ensured that it was stable and not vibrating during the experiments.  This was verified by repeated measurements and the results from each measurement were about the same. Moreover, due to the non-linearity property of the rubber band, it was made sure that the opening width of the body-powered split hook was the same in every experiments for both  56 terminal devices. In addition, the measurements of pinch force (or normal force) were performed before and after each slip measurement to ensure that the normal force was kept constant in every experiments. 3.3 Frictional Properties of Terminal Devices  Slip measurements were performed on two types of terminal devices by varying the types of materials and the loading rates to examine the frictional properties of the surfaces in contact between the terminal devices and the gripped objects.  The stick-slip phenomena were observed in the experiments.  Figure 3.12 shows a typical stick-slip motion observed in this study. 0 2 4 6 8 10 12 14 0 2 4 6 8 Time (sec) T a n g e n ti a l F ri c ti o n  F o rc e  ( N )  Figure 3.12 Typical tangential friction force versus time for slip measurements  In Figure 3.12, the tangential friction force ( SF ) increases until the beginning of the slippage, then, after the sudden decrease of the friction force, the phenomenon repeated itself.  The reason the increase in frictional load is not linear is that the surface of the  57 prosthesis is not "rigid". Because the surface material is compressible, there is slow and minute slippage occurring before the actual slippage, and so part of the load force was converted to kinetic energy to allow the object to have tiny slipping. From the experiments, the instant when slippage begins could be identified.  Using the equation 3.2, the static friction coefficient ( Sµ ) could be calculated from the tangential friction force ( SF ) when slippage occurs at a constant normal force ( NF ). 3.3.1 Static Friction Coefficients of Body-Powered Split Hook vs. Otto Bock Myohand DMC VariPlus Speed ®   Table 3.1 shows the mean ± standard deviation of the static friction coefficients ( Sµ ) of the surfaces in contact between the body-powered split hook and the gripped objects at various loading rates.  The results showed that the static friction coefficients ( Sµ ) between the lining surface of the body-powered split hook (i.e. neoprene) and different types of materials varied.  The findings suggested that, for all loading rates, the static friction coefficients ( Sµ ) between the neoprene lining surface of the body-powered split hook and the object made of plastic were the highest, followed by the static friction coefficients ( Sµ ) between the lining surface of the body-powered split hook and the objects made of metal and wood used in this study, respectively.   58 Table 3.1 Static friction coefficients ( Sµ ) of the materials in contact between the body-powered split hook and different types of materials at various loading rates Materials Loading Rates Low Medium High Metal 0.83 ± 0.03 0.79 ± 0.01 0.69 ± 0.03 Plastic 0.91 ± 0.03 0.86 ± 0.03 0.79 ± 0.02 Wood 0.78 ± 0.02 0.71 ± 0.02 0.64 ± 0.03  Table 3.2 shows the mean ± standard deviation of the static friction coefficients ( Sµ ) of the surfaces in contact between the Otto Bock Myohand DMC VariPlus Speed ® and the gripped objects at various loading rates. The results showed that the static friction coefficients ( Sµ ) between the PVC glove of the myoelectric hand and different types of materials were not constant.  The findings suggested that, for all loading rates, the static friction coefficients ( Sµ ) between the PVC glove of the myoelectric hand and the object made of plastic were the highest, followed by the static friction coefficients ( Sµ ) between the glove of the myoelectric hand and the objects made of wood and metal used in this study, respectively. Table 3.2 Static friction coefficients ( Sµ ) of materials in contact between the Otto Bock Myohand DMC VariPlus  Speed ®  and different types of materials at various loading rates Materials Loading Rates Low Medium High Metal 0.74 ± 0.04 0.67 ± 0.03 0.59 ± 0.03 Plastic 0.97 ± 0.02 0.91 ± 0.02 0.85 ± 0.01 Wood 0.87 ± 0.04 0.81 ± 0.03 0.74 ± 0.03   59   Table 3.1 and Table 3.2 show that the static friction coefficients ( Sµ ) of the surfaces in contact between the neoprene lining surface of the body-powered split hook and metal were larger than that of the surfaces in contact between the PVC glove of myoelectric hand and metal.  This imply the object made of metal used in this study can be better gripped by the body-powered split hook with neoprene lining than by the myoelectric hand with PVC glove.  However, this was not the case for the plastic and wood materials.  The static friction coefficients ( Sµ ) of the surfaces in contact between the PVC glove of myoelectric hand and plastic and wood were greater than that of the surfaces in contact between the neoprene lining surface of the body-powered split hook.  These findings imply that the myoelectric hand with PVC glove can provide a better grip than the body-powered split hook with neoprene lining when holding the objects made of plastic and wood.  The possible reason associated with these findings is that greater static friction coefficient ( Sµ ) means that it will need stronger external disturbances at lower loading rate to cause slipping of the gripped objects from the terminal devices.  It should be noted that these findings are specific to terminal device material, object material and roughness. 3.3.2 Effects of Loading Rates on Coefficient of Friction of Terminal Devices Figure 3.13 shows the static friction coefficient ( Sµ ) of the surfaces in contact between terminal devices and metal versus load rate coefficient (θ&  ), comparing between body-powered split hook with neoprene lining and myoelectric hand with PVC glove.  The results showed that, within the range of loading rates applied in this study, as the loading  60 rate increased, the static friction coefficients ( Sµ ) of the surfaces in contact between the neoprene lining of body-powered split hook and metal and that of the surfaces in contact between the PVC glove of myoelectric hand and metal decreased. 0.5 0.6 0.7 0.8 0.9 0 0.1 0.2 0.3 0.4 Load Rate Coefficient (s -1 ) S ta ti c  F ri c ti o n  C o e ff ic ie n t Body-powered hook Myoelectric hand  Figure 3.13 Static friction coefficient of the surfaces in contact between terminal devices and metal vs. load rate coefficient: comparing between body- powered split hook with neoprene lining and myoelectric hand with PVC glove.  From the low loading rate to the high loading rate, the static friction coefficients ( Sµ ) between the neoprene lining of body-powered split hook and metal decreased 17%; whereas the static friction coefficients ( Sµ ) between the PVC glove of myoelectric hand and metal decreased 20%.  However, from the medium loading rate to the high loading rate, the static friction coefficients ( Sµ ) of the surfaces in contact between the neoprene lining of body-powered split hook and metal and that of the surfaces in contact between the PVC glove of myoelectric hand and metal decreased 13% and 10%, respectively.  From the  61 low loading rate to the medium loading rate, the static friction coefficients ( Sµ ) between the neoprene lining of body-powered split hook and metal decreased 5%; whereas the static friction coefficients ( Sµ ) between the PVC glove of myoelectric hand and metal decreased 8%. The results indicated that at low loading rate, the percent decrease was higher for lower rate friction coefficient than high friction rate coefficient.  The reason for this may be because the static friction coefficient of the body-powered hook was more than that of the myo-electric hand, hence indicating that the lower decrease of the friction coefficient of the body-powered hook at low loading rates may be due to the greater stability provided by the higher friction coefficient. Figure 3.14 shows the static friction coefficient ( Sµ ) of the surfaces in contact between terminal devices and plastic versus load rate coefficient (θ&  ), comparing between body-powered split hook with neoprene lining and myoelectric hand with PVC glove.  It was observed that, within the range of the loading rates applied in this study, as the loading rate increased, the static friction coefficients ( Sµ ) of the surfaces in contact between the neoprene lining of body-powered split hook and plastic and that of the surfaces in contact between the PVC glove of myoelectric hand and plastic decreased.   From the low loading rate to the high loading rate, the static friction coefficients ( Sµ ) between the neoprene lining of body-powered split hook and plastic decreased 13%; whereas the static friction coefficients ( Sµ ) between the PVC glove of myoelectric hand and plastic decreased 12%. Moreover, the results also showed that, from the medium loading rate to the high loading rate, the static friction coefficients ( Sµ ) of the surfaces in contact between the neoprene lining of body-powered split hook and plastic and that of the surfaces in contact between  62 the PVC glove of myoelectric hand and plastic decreased 8% and 7%, respectively.  From the low loading rate to the high loading rate, the static friction coefficients ( Sµ ) between the neoprene lining of body-powered split hook and plastic decreased 5%; whereas the static friction coefficients ( Sµ ) between the PVC glove of myoelectric hand and plastic decreased 6%.  The reason that the percent decrease of the static friction coefficients ( Sµ ) of body-powered split hook and myoelectric hand were about the same might be because both body-powered split hook and myoelectric hand have relatively large static friction coefficient ( Sµ ); thus they both can provide fairly stable grip. 0.7 0.8 0.9 1 1.1 0 0.1 0.2 0.3 0.4 Load Rate Coefficient (s -1 ) S ta ti c  F ri c ti o n  C o e ff ic ie n t Body-powered hook Myoelectric hand  Figure 3.14 Static friction coefficient of the surfaces in contact between terminal devices and plastic vs. load rate coefficient: comparing between body- powered split hook with neoprene lining and myoelectric hand with PVC glove.  Figure 3.15 shows the static friction coefficient ( Sµ ) of the surfaces in contact between terminal devices and wood versus load rate coefficient (θ&  ), comparing between  63 body-powered split hook with neoprene lining and myoelectric hand with PVC glove.  The results show that, within the range of the loading rates applied in this study, as the loading rate increased the static friction coefficients ( Sµ ) of the surfaces in contact between the neoprene lining of body-powered split hook and wood and that of the surfaces in contact between the PVC glove of myoelectric hand and wood decreased. 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 Load Rate Coefficient (s -1 ) S ta ti c  F ri c ti o n  C o e ff ic ie n t Body-powered hook Myoelectric hand  Figure 3.15 Static friction coefficient of the surfaces in contact between terminal devices and wood vs. load rate coefficient: comparing between body- powered split hook with neoprene lining and myoelectric hand with PVC glove.  From the low loading rate to the high loading rate, the static friction coefficients ( Sµ ) of the surfaces in contact between the neoprene lining of body-powered split hook and wood and that of the surfaces in contact between the PVC glove of myoelectric hand and wood decreased 18% and 15%, respectively.  In addition, from the medium loading rate to the high loading rate, the static friction coefficients ( Sµ ) between the neoprene  64 lining of body-powered split hook and wood decreased 10%; whereas the static friction coefficients ( Sµ ) between the PVC glove of myoelectric hand and wood decreased 9%. From the low loading rate to the high loading rate, the static friction coefficients ( Sµ ) of the surfaces in contact between the neoprene lining of body-powered split hook and wood and that of the surfaces in contact between the PVC glove of myoelectric hand and wood decreased 9% and 6%, respectively.   The results indicated that at low loading rate, the percent decrease was higher for lower rate friction coefficient than high friction rate coefficient.  The reason for this may be because the static friction coefficients ( Sµ ) of body-powered hook was less than that of myoelectric hand. It should be pointed out that the effect of those curves in figure 3.13 - 3.15 are specific to the particular material that was used for a particular terminal device.  Should the material of terminal device change, those curves will also change.  Those curves are totally depended on the shape, the roughness and hardness of the surface. The overall findings of this study suggested that the static friction coefficient ( Sµ ) decreased as the loading rate increased.  These are in agreement with studies by Johannes et al, (1973) and Richardson and Nolle (1976) which reported that the static friction coefficients ( Sµ ) are dependent with the rate of application of the tangential load, i.e. the static friction coefficients ( Sµ ) decreased in an exponentially manner with increasing loading rate and eventually reached a constant value.  This is because the loading rate is directly related to the contact time.  It has been reported that as the contact time increases, the static friction coefficient ( Sµ ) also increases (Richardson & Nolle, 1976).  65 Furthermore, the percent decrease of the static friction coefficients ( Sµ ) from low loading rate to high loading rate of the body-powered split hook and metal was less than that of the myoelectric hand.  On the contrary, the percent decrease of the static friction coefficients ( Sµ ) from low loading rate to high loading rate of the myoelectric hand and wood was less than that of the body-powered split hook.   At low loading rate, the percent decrease is higher for lower rate friction coefficient than high friction rate coefficient.  The reason for this may be because the static friction coefficients ( Sµ ) of body-powered hook was less than that of myoelectric hand. 3.4. Conclusion In this study, a method to measure friction as a function of loading rate at a typical activity of daily living was established.  A body-powered split hook and an Otto Bock Myohand DMC VariPlus Speed® were evaluated for the frictional properties of the materials in contact between their lining surfaces and the gripped objects made of metal, plastic, and wood.  The findings from this study indicated that the static friction coefficients ( Sµ ) of the materials in contact of the body-powered split hook and the myoelectic hand were dependent on material properties and the loading rates.  Although the static friction coefficients ( Sµ ) vary with materials, it is likely that in most materials the static friction coefficients ( Sµ ) will decrease as the loading rate increases.  This finding is in agreement with previous studies by Johannes et al, (1973) and Richardson and Nolle (1976) which reported that the static friction coefficients ( Sµ ) are dependent with the rate  66 of application of the tangential load, i.e. the static friction coefficients ( Sµ ) decreased in an exponentially manner with increasing loading rate and eventually reached a constant value. The findings from this study are important because the slippage of the objects is an issue.  Knowing the static friction coefficients ( Sµ ) will help to improve the design of prosthetic terminal devices.  For example, most current terminal devices simply grip with high enough grip force to hold somewhat heavy object in order to prevent slipping. However, with this technique it can become a problem when the prosthetic user is trying to grip or manipulate delicate or very heavy objects.  That is if the grip force is too large it can damage delicate objects, but if the grip force is not large enough it can cause slippage of heavy objects.  Moreover, objects in daily live activities comes in a variety of types of materials, size or shape, it is important for a terminal device to be able to adapt its grip to the type of object it is grasping.  The prosthetic terminal devices should have the sensors that can detect changes in friction coefficients and provide accurate adjustment of applied normal force in order to prevent the objects from unexpectedly slipping.  In fact, Otto Bock SensorHand® is the only commercially available hand prosthesis that is capable of automatically tightening the applied grip force of the hand in the presence of an external perturbation (Puchhammer, 2000). Moreover, the results from this study may be useful in selecting appropriate prosthetic terminal devices to handle different types of materials when prescribing a prosthesis for the amputee. However, there are some limitations in this study.  First of all, the static friction coefficient ( Sµ ) varies due to several factors including the materials of both the terminal device and the object being gripped, roughness of the surface, shape, hardness, elasticity,  67 temperature, humidity, surfaces (e.g. oily, wet, slippery, soapy), contact area, and angle.  In this study, the materials of objects chosen were metal, plastic and wood that were in rectangular shape with same surface roughness and hardness.  In addition, the surface in contact of the body-powered split hook was made of neoprene and that of the myoelectric hand was made of PVC. Therefore, it should be pointed out that the static friction coefficients ( Sµ ) reported in this study are specific to the material properties of the objects and the lining surfaces of the terminal devices used in this study.  Another limitation is that the test results only applied to the range of loading rates in this study.  However, these are estimated loading rate in activities of daily living.  If the range of the loading rates changes, the static friction coefficients ( Sµ ) will also change.    68     Chapter 4 Prescription Protocol for Upper Limb Prostheses  Sudden loss of a hand or arm is a devastating event for any individual.  It can result in serious physical, psychological and vocational consequences.  From the literature review in Chapter 2, it has been reported that upper limb amputations are usually trauma-related, particularly in industrial settings.  Amputees who are affected by traumatic amputation tend to be young, active, and economically productive individuals (Esquenazi, 2004).  Adapting to limb loss and gaining employment after the amputations are major challenges.  Thus, it is very important for the amputees to regain considerable upper limb function to maintain independence.  There are several types of prostheses presently available that endeavor to address the needs of individuals with upper limb amputations.  Unfortunately, an upper limb prosthesis can only compensate for the capability of a human hand and arm to a limited extent. Currently, there are a variety of prosthetic components available on the market. Nevertheless, the most technologically advanced upper limb prosthesis may not be the  69 most appropriate one for all amputees.  From the literature review, each type of prosthesis has its own advantages and disadvantages and is suitable for different types of working conditions.  For instance, myoelectric prosthesis is the preferred type of prosthesis for individuals who involve in light-duty work conditions; whereas body-powered prosthesis is used by those who are engaged in heavy-duty work conditions (Kejaa, 1993; Silcox et al., 1993).  In addition, the findings from Chapter 3 suggest that there are differences in the frictional properties between each type of terminal devices (i.e., a body-powered split hook and a myoelectric hand) and the gripped objects made of various materials.  This suggests that each type of terminal devices is suitable for handling different types of materials.  The prosthetic devices that may be considered to be the best for one individual may not be the best for another individual.  Studies indicate that the rejection rates for upper limb prostheses are high.  The rejection rates for body-powered prostheses and myoelectric prostheses, can be as high as 66% (Kruger & Fishman, 1993) and 75% (Crandall & Tomhave, 2002), respectively. The most obvious reason for prosthetic rejection is failure to satisfy the needs of the prosthetic users.  Therefore, in prescribing a prosthesis, the choice of an appropriate prosthesis should be decided based on the needs of the individual. To the best of our knowledge, from an extensive literature review in Chapter 2, currently no standard prescription protocol for upper limb prostheses exists.  Having a standard prescription protocol that best serve the needs of the individual prosthetic users may bring a number of benefits including decreasing the rate of abandonment, optimizing the cost-effective use of the prosthetic device, and making quality of care more consistent and efficient.  Thus, in this chapter a standard prescription protocol for upper limb prostheses will be proposed.  In order to prescribe an appropriate prosthesis for the  70 amputee, one of the key factors that need to be considered is the amputee’s needs.  The prescription protocol proposed in this study aims to assess the needs of the amputee and to assist in the selection of an appropriate upper limb prosthesis for the amputee.  There are several methods to assess the amputee’s needs, such as a checklist, a questionnaire, and a scoring system. However, the responses from a questionnaire or a checklist cannot be quantified the relative importance of each factor related to the amputee's needs.  Moreover, in clinical practice, when a prosthetist prescribes a prosthesis to an amputee, the prosthetist need to consider a lot of factors related to the selection of an appropriate prosthesis for the amputee.  Thus, there is need for a method that can be used to assist the prosthetist to be able to prescribe an appropriate prosthesis to the amputee in a systematic and objective approach. In order to have a protocol that can be used to assess and document the amputees’ needs in a systematic way and is able to use for comparisons among different cases, a scoring system should provide a better objective approach.  Therefore, a scoring system is proposed as part of the comprehensive prescription protocol for upper limb prostheses in the current study.  The purpose of the scoring system is to take into account the factors related to the selection of a prosthesis to meet the needs of the amputee.  This scoring system will serve as a tool to assist in the selection of a prosthetic device that best fits with the needs of the individual with an upper limb amputation.   With regard to the methodological considerations to obtain “scores”, there are several methods that are available.  Those methods are common optimization algorithms such as curve-fitting techniques, least squares, and partial least squares method which require discrete-time data.  However, this study will obtain “scores” from the standard of  71 practice of different experts or practitioners in this field.  Because not all organizations or companies have their professional standard of practices made available in the way that the data can be collated, the experts were provided with simple hypothetical situations so that it is more direct for us to gather their professional standard of practices.  The practical approach to collect the standard of practice is via survey.  A research method that can be used to obtain “score” from collated data of standard of practices via the survey is called a factorial survey approach.  Therefore, the factorial survey is proposed as a method used to develop a scoring system in this study.  In the following, the factorial survey approach will be described first.  The application of this approach will be presented in the factorial vignettes and analysis section, followed by the results in vignette ratings and factors in selecting types of upper limb prostheses, and the proposed prescription protocol for upper limb prostheses.  4.1 Factorial Survey Approach The factorial survey was developed by Rossi and Anderson (1982) as a research method specifically designed to assess how judgments are made over multidimensional phenomena.  The primary objective of the factorial survey is to uncover the “shared and idiosyncratic principles of judgments” (Rossi & Nock, 1982, p. 10).  This objective is based on the assumptions that human judgments are individually and socially (i.e. shared with others) structured (Rossi & Anderson, 1982).  The factorial survey approach can be referred to as a hybrid technique that combines the technique used in a multivariate experimental design with a simple survey approach.  It adopts the primary strength of the  72 experimental tradition which is the concept of factor orthogonality and borrows the greater richness in complexity and realism from the survey tradition (Rossi & Anderson, 1982).   The factorial survey approach allows one to evaluate judgment behavior under conditions that are close to real-life judgment-making situations in which selected factors believed to influence the judgment process are simultaneously manipulated.  This approach is suitable for examining normative beliefs that characterize a particular social group in relation to an object of shared interest (Love et al., 1996).  The factorial survey is able to uncover the structure which underlies the normative judgments and can determine the relative weights of a wide range of factors that influence the judgments.  Ludwick and Zeller (2001) assert that the factorial survey can also be used to identify areas of consensus regarding complex social phenomena and for the development of important concepts. The factorial survey has been successfully applied to diverse variety of topics. For example, applications concerned with social behavior included child abuse (Garrett, 1982; O’Toole et al., 1999), mental illness (Thurman et al., 1988), and sexual harassment (Rossi & Weber-Burdin, 1983).  Previous decision making applications include making the decision to drink or drive (Thurman, 1986), and the selection of immigrants (Jasso, 1988). Nursing research applications include clinical decision making (Brown et al., 1997; Ludwick, 1999) and nurse judgments of self-neglect (Lauder et al., 2001).  Other applications include consumer preferences (Feitelson, 1992), political use of income (Cahan, 1996), the acceptability of HIV vaccine trial designs (Hennessey et al., 1996), and perception of child care quality (Shlay et al., 2005).  The wide variety of applications of the factorial survey approach provides evidence to its versatility and utility as a research method.  73 In the factorial survey approach, the main elements are the vignettes.  A vignette is a short description of multidimensional phenomenon that contains information considered to be relevant to the judgment process and that is presented to respondents to obtain a judgment about that phenomenon.  Each respondent may be given as few as 3 or as many as 30 vignettes to judge.  The vignettes provide a relatively complex case scenario which is closely related to real-world decision making.  A vignette contains dimensions and levels, both of which comprise the independent variables in the study.  Dimensions refer to variables that are thought to influence the judgments and within each dimension there are a number of levels.  The selection of dimensions and levels for the vignettes should be guided by theory and research (Jasso, 2006; Rossi & Anderson, 1982), extra-theoretical reasoning and conventional wisdom (Jasso, 2006).  A vignette is constructed by randomly assigning individual levels within each dimension to each vignette.  The random combination of levels of each dimension ensures that the vignettes characteristics are uncorrelated with each other (Byers & Zellers, 1995).  The number of independent variables in the vignettes is commonly five to ten (Taylor, 2006).  The other type of variables is the dependent variables which are in the form of the decision (s) to be made at the end of each vignette.    The factorial surveys often have one or two decisions to be made (dependent variables).  The dependent variables may be framed as categorical, ordinal, or interval scales.  However, the interval scales (usually a Likert-type scale) give the most sensitive data analysis.     74 4.2 Factorial Vignettes and Analysis 4.2.1 Development of the Vignettes  The first step in designing a factorial survey was determining what dimensions (i.e., essential characteristics or factors) of the description to include.  Dimensions or the independent variables that are thought to influence the judgments in selecting the type of prosthetic device to be included in this factorial survey were identified through the literature review (Brenner, 1992; Dakpa & Heger, 1997; Kejlaa, 1993; Millstein et al., 1986; Stark & Leblanc, 2004).  From the literature review, five dimensions (factors) that contribute to the selection of the types of upper limb prosthetic devices were selected for vignette construction: • gross body movements of shoulder, upper arm and chest; • work condition; • lifting heavy objects; • grip force; and • performing above-shoulder maneuvers.  The list of dimensions and associated levels (independent variables) are shown in Table 4.1.  Each dimension contains two levels.  For example, in this study “grip force” is considered to be one of the dimensions.  Within the dimension “grip force”, there are two levels which are “low” and “high”.  The independent variables (dimensions and levels) in the present study are categorical variables.  The categorical variables are the variables which may be assigned into groups or categories, but there is no clear ordering to the categories (e.g. the grip force is “low” or “high”).  The full combination of dimensions and  75 levels yields 32 vignettes (five dimensions with two levels, i.e. 2 x 2 x 2 x 2 x 2 design). The list of all 32 possible vignettes is included in Appendix A. The structure of vignette sentence was designed by arranging the dimensions and levels in the vignettes to be coherent and internally consistent.  Vignettes were randomly generating by randomly selecting a level from each of dimensions, until each dimension was represented in the vignette and a complete short description was formed.  This random process was repeated until all the vignettes required for this study were constructed. The effect of this procedure is that each level within each dimension is equally likely to appear in the vignettes and that each of the dimensions is roughly uncorrelated with every other dimension.  A sample vignette is presented in Table 4.2.  Table 4.1   Vignette dimensions and levels   Dimension – Gross body movements of shoulder, upper arm and chest 1. Sufficient (i.e. muscle strength ≥ grade 4) 2. Limited (i.e. muscle strength < grade 4)  Dimension – Work condition 1. Heavy duty (i.e. wet, dirty, physical demanding) 2. Light duty (i.e. dry, clean, not physical demanding)  Dimension – Lifting heavy objects ( > 11 lbs) 1. Frequently (i.e. 3-5 hours daily) 2. Rarely (i.e. not daily)  Dimension – Grip force 1. Low (i.e. 0-11 lbs.) 2. High (i.e. > 11 lbs)  Dimension – Performing above-shoulder maneuvers 1. Frequently (i.e. 3-5 hours daily) 2. Rarely (i.e. not daily)   76 The factorial survey questions in this study are the rating of the appropriateness of a patient with an upper limb amputation to be fitted with a myoelectric prosthesis (dependent variables).  The questions and their associated rating scales are shown in the sample vignette in Table 4.2.  The two most common types of upper limb amputation are the trans- radial and trans-humeral amputation.  Therefore, the two questions in the factorial survey addressed upper limb prosthetic experts’ standard of practices on the appropriateness of patients with trans-radial and trans-humeral amputation to be fitted with myoelectric prostheses.   The rating scale associated with these questions ranged from 1 = “Not appropriate at all” to 9 = “Very appropriate”.  Each point on the scale is treated as an equal interval.  Table 4.2   Sample vignette    A patient with an upper limb amputation is hoping to return to work. He has sufficient gross body movements of the shoulder, upper arm, and chest. He is required to work in a light duty work condition most of the time. His work rarely involves lifting heavy objects. High grip force is expected in gripping and moving objects. He rarely needs to perform above-shoulder maneuvers.  For trans-radial amputation: In your opinion, how appropriate would it be for the patient to be fitted with a myoelectric device?     Not appropriate at all                                                                             Very appropriate                   1---------2--------3---------4---------5---------6---------7---------8---------9  For trans-humeral amputation: In your opinion, how appropriate would it be for the patient to be fitted with a myoelectric device?     Not appropriate at all                                                                             Very appropriate                   1---------2--------3---------4---------5---------6---------7---------8---------9   77 4.2.2 Vignette Administration  In this study, the factorial survey approach was proposed as a method that can be used to develop a scoring system in a prescription protocol for upper limb prostheses.  It is important to note that this is a preliminary study.  We have approached 60 upper limb prosthetic experts for their standard of practices.  Only twenty upper limb prosthetic experts eventually submitted their responses.  The survey was administered via electronic mail.  Each participant received a survey packet which consists of 20 vignettes that were constructed for each participant (see an example in Appendix B).  The participants were asked to rate each vignette regarding the appropriateness in selecting myoelectric prostheses for individuals with trans-radial and trans-humeral upper limb amputation on a scale of 1 (Not appropriate at all) to 9 (Very appropriate).  Because there were 20 vignettes for each of the 20 participants, the sample size for this study was 400.  4.2.3 Data Analysis One major advantage of the factorial survey technique is that the unit of analysis is the vignette, not the number of participants (Ludwick & Zellers, 2001).  Because vignettes contain dimensions and levels that are randomly assigned, thus each vignette is considered independent (Rossi & Anderson, 1982).  Therefore, the sample size is the number of vignettes multiplied by the number of participants.   Thus, a small number of respondents can generate a large number of observations.  Rossi and Anderson (1982) state that “If each n respondent rates separate respondent subsamples of m factorial objects, the resulting data are nm = N judgments, J1.  Since adding random samples to random samples simply produces larger random samples, it makes sense to pool the judgments, producing a single  78 sample of judgments of size N” (p. 32).  The preferred model for the factorial survey analysis is the ordinary least squares (OLS) regression.  4.2.3.1 Regression Model The ordinary least squares (OLS) regression is typically used to analyze the data in factorial surveys.  The key benefits of regression analysis are that: • It can indicate if independent variables in the vignettes have a significant relationship with a judgment of the respondent (dependent variable). • It can indicate the relative strength of different independent variables’ effects on a judgment of the respondent (dependent variable). • It can also help make predictions.  In its simplest form, where there is only one independent variable, regression model is called bivariate regression.  The bivariate regression model is described as follows (Field, 2000): ε++= bXbY 0                                           (4.1) where Y is the dependent variable, which is the outcome variable that the researcher is trying to explain; 0b  is the intercept; b  is the regression coefficient of the independent variable; X  is the independent variable; ε  is the error or residual term.  79 The intercept )( 0b  is given by the equation: XbYb −=0                                                      (4.2) where Y  is the average value of the dependent variable; b  is the regression coefficient of the independent variable; X  is the average value of the independent variable.  The regression coefficient of the independent variable (b ) is also referred to as the unstandardized regression coefficient.  The unstandardized regression coefficient (b ) indicates the effect of a one-unit change in the independent variable on the dependent variable.  The unstandardized regression coefficient is given by:  ∑ ∑ − −− = 2)( ))(( XX YYXX b i ii                                   (4.3) where iY  is the ith observation on the dependent variable, from 1 to n; iX       is the ith observation on the independent variable from 1 to n; Y  is the average value of the dependent variable; X  is the average value of the independent variable.  n is the number of observations   80 For research study that has more than one independent variable, multiple regressions can be used to analyze data.  A multiple regression model is shown below (Field, 2000).                      iijjiii XbXbXbbY ε+++++= ...22110                      (4.4) where iY  is the dependent variable, which is the outcome variable that the researcher is trying to explain, i = 1 to n; 0b  is the intercept; jb  is the jth regression coefficient, j = 1 to k; ijX  is the ith observation of jth independent variable, i = 1 to n, j = 1 to k; k  is the number of independent variables; n is the number of observations; iε  is the error or residual term, i = 1 to n.  In this study, there are multiple independent variables (i.e., gross body movements of shoulder, upper arm and chest (sufficient, limited); work condition (heavy duty, light duty); lifting heavy objects (frequently, rarely); grip force (low, high); and performing above-shoulder maneuvers (frequently, rarely)).  Therefore, multiple regression analyses were performed.  The significant level of statistic was set at the p-value of 0.05.  Table 4.3 presents an example of survey responses.  81 In the present study, the vignettes dimensions’ levels are categorical variables (e.g. the levels “low” or “high” in the dimension “grip force”); thus they can not be quantified in a meaningful way.  In order to be able to perform regression analysis, it is necessary to represent different levels of the various dimensions by dummy coding such as zero’s for one level and one’s for the remaining level (Kerlinger & Pedhazur, 1973; Rossi & Nock, 1982).  Table 4.4 presents an example of the categorical variables in each dimension in the survey responses that are converted into dummy coding variables.  Table 4.3   Example of survey responses Vignette Gross body movements Work condition Lift heavy object Grip force Perform above shoulder maneuver Vignette Rating  1 Limited Heavy duty Frequently High Frequently 6 2 Sufficient Heavy duty Frequently Low Rarely 5 3 Sufficient Light duty Rarely High Rarely 7 4 Sufficient Light duty Rarely High Frequently 7 5 Limited Light duty Frequently High Rarely 6 6 Limited Heavy duty Rarely Low Frequently 5 7 Limited Light duty Frequently High Frequently 7 8 Sufficient Heavy duty   Frequently Low Rarely 4 9 Limited Light duty  Frequently Low Rarely 2 10 Limited Heavy duty Frequently High Rarely 5 . . . . . . . . . . . . . . . . . . . . . 400 Limited Light duty Rarely High Rarely 6   When performing the data analysis, one level for each dimension was omitted to prevent multi-collinearity.  The choice of omitted levels is arbitrary, thus in this study the first level in each dimension was omitted from the analysis, i.e. sufficient (gross body  82 movements), heavy duty (work condition), frequently (lifting heavy object), low (grip force), and frequently (performing above-shoulder maneuvers).  Therefore, the multiple regression model in equation 4.4 can be written as follows:  Vignette Ratings )( iY = 0b  + 1b  (Limited gross body movements)i + 2b (light duty work condition)i + 3b (rarely lifting heavy object)i + 4b (high grip force)i + 5b (rarely perform above shoulder maneuvers)i         (4.5)  Consequently, unstandardized regression coefficients ( jb ) express the extent to which vignettes ratings are affected by the presence of a given level in the vignette compared to the omitted level.  For example, if 1b  = 0.5, it indicates that when “limited gross body movements” is present in the vignette, it raised the vignette ratings by 0.5 compared to when the omitted level “sufficient gross body movements” is present.  This regression analysis compares the contribution of each level within the dimensions to the variation in vignette ratings.  However, it does not permit a comparison of which dimensions are most important. In order to examine the contribution of each dimension to vignette ratings, a method of “coding proportional to effect” (Boyle, 1970; Rossi & Anderson, 1982; Werts & Linn, 1971) can be used.  Coding proportional to effect is the technique that requires the recoding of dummy variable in each non-omitted level into the size of its unstandardized regression coefficient ( jb ).  The omitted level of each dimension is coded as zero.  For example, if 1b  83 = 0.5, then the dummy variable of the “limited gross body movements” will be recoded into 0.5.  Then, perform another regression analysis.  Regression of the vignette ratings as a function of the effect-coded dimensions produces both unstandardized ( jb ) and standardized ( jβ ) coefficients.  The unstandardized coefficients ( jb ) for the dimensions are equal (or approximately so) to one.  From this analysis, the standardized regression coefficients ( jβ ) can be used to assess the relative importance of each dimension compared to all others.  The standardized regression coefficient ( jβ ) can be obtained by multiplying the unstandardized regression coefficient ( jb ) by the ratio of the standard deviation of the independent variable ( xSD ) to the standard deviation of the dependent variable ( ySD ) as shown in the following equation:             = y x jj SD SD bβ                       (4.6)   4.2.3.2 Overall Model Fit and Effects of Individual Variables The power of the entire model and the relative strength of independent variables in the vignette on the decision is evaluated by the proportion of variance explained (R2) (Cohen, 2002).  The R2 lies between zero and one.  R2 represents the amount of variance in the outcome explained by the model (SSM) relative to the total variation (SST) which can be calculated as: T M SS SS R =2                                                           (4.7)  84 Table 4.4 Example of dummy coding variables from the survey responses Vignette Gross body movements Work condition Lift heavy object Grip force Perform above shoulder maneuver Rating  Sufficient Limited  Heavy duty  Light duty Frequently Rarely  Low High Frequently  Rarely 1 0 1 1 0 1 0 0 1 1 0 6 2 1 0 1 0 1 0 1 0 1 0 5 3 1 0 0 1 0 1 0 1 0 1 7 4 1 0 0 1 0 1 0 1 1 0 7 5 0 1 0 1 1 0 0 1 0 1 6 6 0 1 1 0 0 1 1 0 1 0 5 7 0 1 0 1 1 0 0 1 1 0 7 8 1 0 1 0 1 0 1 0 0 1 4 9 0 1 0 1 1 0 1 0 0 1 2 10 0 1 1 0 1 0 0 1 0 1 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 0 1 1 0 1 0 1 0 0 1 6  85 where 2 1 )ˆ( YYSS n i iM −=∑ = , where iŶ  is the ith predicted value of dependent variable; Y  is the average value of dependent variable; n  is the number of observations. 2 1 )( YYSS n i iT −=∑ = , where iY  is the ith observed value of dependent variable; Y  is the average value of dependent variable; n  is the number of observations.  The overall goodness of fit of the regression model can be evaluated by using the F- test.  The F-value can be calculated as follows:  1−− = k n SS k SS F E M                                                (4.8) where 2 1 )ˆ( YYSS n i iM −=∑ = , where iŶ  is the ith predicted value of dependent variable; Y  is the average value of dependent variable; n  is the number of observations. 2 1 )ˆ(∑ = −= n i iiE YYSS , where iY  is the ith observed value of dependent variable;  86 iŶ  is the ith predicted value of dependent variable; n  is the number of observations.  k  is the number of the independent variables  The significance of the F-statistic is obtained by referring to the F-distribution with k and (n – k -1) degrees of freedom.  The F-test is the most critical in determining if the overall model is significant.  If the F-value is insignificant, there is no further interpretation of the model.  However, if the F-value is significant, it is highly likely that at least one or more regression coefficients are significant. The R2 and the F-value are used to assess the overall model fit, but they do not tell us about the individual contribution of variables in the model.  The effects of the individual variables used to explain the dependent variable can be assessed by the t-statistics which can be calculated as follows: j b j j SE b t =                                  (4.9) where  jt  is the t-statistics for jth independent variables, j = 1 to k; jb  is the jth regression coefficient from, j = 1 to k; j bSE  is the standard error of estimation of jb k  is the number of independent variables;   87 The t-statistic tests the null hypothesis that the value of b is zero.  Therefore, if the t-statistic is significant, it would mean that particular independent variable contributes significantly to the dependent variable.   4.3 Vignette Ratings 4.3.1 Trans-Radial Amputation Table 4.5 shows the percentage of respondents’ selection for the rating scores from 1 to 9.  The distribution of vignette ratings for trans-radial amputation, as shown in Table 4.5, suggests that there is no clustering of the rating scores and no piling up of the responses on the two extreme ratings. The mean of all ratings is 5.31 with a standard deviation of 1.64.  Table 4.5 Trans-radial amputation: The percentage of respondents’ selection for the rating scores from 1 to 9 (N = 400).  Rating Score % of Respondents’ Selection 1 2 3 4 5 6 7 8 9 Mean = 5.31;SD = 1.64 7.25 11.25 10.50 13.50 15.75 12.00 11.50 8.75 9.50    88 Table 4.6 presents the regression analysis of the effects of upper limb prosthetic selection characteristics on the ratings of the appropriateness in fitting with a myoelectric device for trans-radial amputation.  Based on the F-test, the overall regression model is highly significant because the F-statistics for the regression is 63.591 for the degree of freedom 5, 394.  The R2 value is 0.447 which implies that the dimensions included in the model explain 44.7% of the variance in the ratings. Since the unstandardized regression coefficients of the levels associated with three factors “work condition”, “grip force”, and “lifting heavy objects” have  p-values of less than 0.05, they are considered statistically significant, i.e. the key factors for the ratings of appropriateness in selecting myoelectric prosthetic device for trans-radial amputation. From Table 4.6, the unstandardized regression coefficient for the “light duty” work condition is 3.434 whereas the values for “high” grip force and “rarely” lifting heavy objects are only 0.486 and 0.421 respectively.  Each unstandardized regression coefficient represents the extent to which ratings are affected by the presence of a particular level in a vignette that is being rated compared to the omitted level.  For instance, the unstandardized regression coefficient of 3.434 associated with the level “light duty” indicates that when this characteristic (light duty) is present in the vignette, it raised the rating by 3.434 compared to when the omitted level (heavy duty) was present.  Even though the “gross body movements of shoulder, upper arm and chest” and “performing above-shoulder maneuvers” influence the appropriateness in selecting myoelectric prosthetic device for trans-radial amputation, the presence or absence of these factors in the vignettes had no significant effect on the rating.    89 Table 4.6 Regression summary: The effects of upper limb prosthetic selection characteristics on the ratings of the appropriateness in fitting with a myoelectric device for trans-radial amputation (N = 400).  Dimension and Level b SE 1. Gross body movements of shoulder, upper arm and chest • Limited  0.197  0.086 2. Work condition • Light duty  3.434*  0.178 3. Lifting heavy objects • Rarely  0.421*  0.143 4. Grip force • High  0.486*  0.162 5. Performing above-shoulder maneuvers • Rarely  -0.078  0.013 Constant 3.111* R2 0.447*  Note: Omitted levels are as follows: 1. Sufficient gross body movements; 2. Heavy duty work condition; 3. Frequently lifting heavy objects; 4. Low grip force; and 5. Frequently performing above-shoulder maneuvers. * p ≤ 0.05  Table 4.7 shows the “coding proportionate to effect” analyses for the ratings of the appropriateness in selecting a myoelectric prosthetic device for trans-radial amputation. This analysis permits a comparative assessment of the importance of each dimension (factor) to the variation in vignette ratings.  In Table 4.7, the unstandardized regression coefficients (b ) and associated standard errors (SE), the standardized regression coefficients (β), and the ranking of the dimension in terms of its overall importance are presented for each dimension.  The standardized regression coefficients indicate the relative effect each dimension has on the overall rating across all vignettes.   90 Table 4.7 Regression of rating on effect-coded dimensions for trans-radial amputation (N = 400)  Dimensions b (SE) β Rank 1. Gross body movements of shoulder, upper arm and chest 0.995(0.39) 0.037 4 2. Work condition 1.001(0.06) 0.648* 1 3. Lifting heavy objects 1.002(0.47) 0.079* 3 4. Grip force 0.999(0.30) 0.09* 2 5. Performing above-shoulder maneuvers 0.997(0.48) 0.015 5 Constant  3.032* R2 0.447* Note: * p ≤ 0.05  The results from the present study suggest that “work condition” represented the most important dimension influencing the ratings on the appropriateness in selecting a myoelectric prosthesis for trans-radial amputation.  The “grip force” ranked second and the “lifting heavy objects” ranked third.  Other dimensions over which the upper limb prosthetic experts placed far less emphasis include “gross body movements of shoulder, upper arm and chest” and “performing above shoulder maneuvers”.  4.3.2 Trans-Humeral Amputation Table 4.8 shows the percentage of respondents’ selection for the rating scores from 1 to 9.   The distribution of vignette ratings for trans-humeral amputation, as shown in Table 4.8, suggests that there is no clustering of the rating scores and no piling up of the responses on the two extreme ratings. The mean of all ratings is 4.47 with a standard deviation of 1.71.   91 Table 4.8 Trans-humeral amputation: The percentage of respondents’ selection for the rating scores from 1 to 9 (N = 400).  Rating Score % of Respondents’ Selection 1 2 3 4 5 6 7 8 9 Mean = 4.47;SD = 1.71 8.00 9.25 10.25 12.25 14.00 15.00 11.50 9.75 10.00   Table 4.9 presents the regression analysis of the effects of upper limb prosthetic selection characteristics on the ratings of the appropriateness in fitting with a myoelectric device for trans-humeral amputation. Based on the F-test, the overall regression model is highly significant because the F-statistics for the regression is 38.491 for the degree of freedom 5, 394.  The R2 value is 0.328 which implies that the dimensions included in the model explain 32.8% of the variance in the ratings.  Since the unstandardized regression coefficients of the levels associated with three factors “work condition”, “lifting heavy objects”, and “performing above-shoulder maneuvers” have p-values of less than 0.05, they are considered statistically significant. From Table 4.9, the unstandardized regression coefficient for the “light duty” work condition is 2.894 whereas the value for “rarely” lifting heavy objects and “frequently” performing above-shoulder maneuvers are only 0.914 and 0.567 respectively.  Even though the “gross body movements of shoulder, upper arm and chest” and “grip force” influence the appropriateness in selecting myoelectric prosthetic device for trans-humeral amputation,  92 the presence or absence of these factors in the vignettes had no significant effect on the rating.  Table 4.9 Regression summary: The effects of upper limb prosthetic selection characteristics on the ratings of the appropriateness in fitting with a myoelectric device for trans-humeral amputation (N = 400)  Dimension and Level b SE 1. Gross body movements of shoulder, upper arm and chest • Limited  0.164  0.098 2. Work condition • Light duty  2.894*  0.186 3. Lifting heavy objects • Rarely  0.914*  0.154 4. Grip force • High  0.115  0.048 5. Performing above-shoulder maneuvers • Rarely  -0.567*  0.176 Constant 2.885* R2 0.328*  Note:   Omitted levels are as follows: 1. Sufficient gross body movements; 2. Heavy duty work condition; 3. Frequently lifting heavy objects; 4. Low grip force; and 5. Frequently performing above-shoulder maneuvers. * p ≤ 0.05   Table 4.10 shows the ‘coding proportionate to effect’ analyses for the ratings of appropriateness in selecting a myoelectric prosthetic device for trans-humeral amputation. This analysis allows a comparative assessment of the importance of each dimension (factor) to the variation in vignette ratings.  In Table 4.10, the unstandardized regression coefficients (b ) and associated standard errors (SE), the standardized regression coefficients (β), and the  93 ranking of the dimension in terms of its overall importance are presented for each dimension.  Table 4.10 Regression of rating on effect-coded dimensions for trans-humeral amputation (N = 400) Dimensions b (SE) β Rank 1. Gross body movements of shoulder, upper arm and chest 1.026(0.89) 0.030 4 2. Work condition 1.001(0.77) 0.531* 1 3. Lifting heavy objects 1.004(0.24) 0.166* 2 4. Grip force 0.991(0.86) 0.021 5 5. Performing above-shoulder maneuvers 0.995(0.39) 0.105* 3 Constant  2.885* R2 0.328* Note: * p ≤ 0.05  The results from the present study suggest that “work condition” represented the most important dimension influencing the ratings on the appropriateness in selecting a myoelectric prosthesis for trans-humeral amputation.  The “lifting heavy objects” ranked second and the “performing above-shoulder maneuvers” ranked third.  Other dimensions over which the upper limb prosthetic experts placed far less emphasis include the “gross body movements of shoulder, upper arm and chest” and the “grip force”.  4.4 Factors in Selecting the Types of Upper Limb Prostheses The findings show that “work condition” factor alone accounted for nearly all of the explained variance in the ratings for both trans-radial and trans-humeral amputation.  It suggests that “work condition” is the most critical factor that influence the judgments of the  94 upper limb prosthetic experts participated in this study in making the selection of prosthetic devices.  It is also interesting to note that in the policy and guideline of a number of private health care insurance companies (UniCare; Empire Blue Cross Blue Shield; Blue Cross Blue Shield of Delaware), “work condition” is one of the criteria to be considered whether the use of myoelectric prosthetic devices is medically necessary. The other factor that significantly contributes to the judgments in selecting prostheses for both trans-radial and trans-humeral amputation is the “lifting heavy objects”. However, its contribution is far less than the “work condition” factor.  Interestingly, “lifting heavy objects frequently” is one of the contraindication criteria for the use of myoelectric prostheses in a medical policy of one of the private medical insurance companies (Blue Cross Blue Shield of Delaware).  A study by Millstein et al. (1986) reported that amputees who had jobs that required heavy lifting used body-powered prostheses because of its ruggedness and durability as it may cause damage to myoelectric prostheses.  The only factor that is virtually unimportant in judging the type of prosthesis for both trans-radial and trans-humeral amputation is the “gross body movements of shoulder, upper arm and chest”.  This may be because, in most cases, individuals with trans-radial amputation will be able to operate both body-powered and myoelectric prostheses easily. Moreover, for the amputees with a long trans-humeral amputation, the “gross body movements of shoulder, upper arm and chest” generally is not a problem because the muscles can still produce enough force to operate the prostheses. For the other two factors “grip force” and “performing above shoulder maneuvers”, the former has a significant influence for the selection of the prosthesis for trans-radial amputation, while the latter influences the judgment for trans-humeral amputation.  For the  95 trans-radial amputation, the “grip force” was relatively important in explaining variance in the judgment ratings, but “performing above-shoulder maneuvers” was not.   This might be because, for trans-radial amputation, the function and performance effectiveness of the terminal device is of the greater concern than that of the functional envelope (i.e. the area in which the amputees can operate the prosthesis).  It has also been reported that there is an increased use of terminal devices by individuals with trans-radial amputation, compared with those with trans-humeral amputation.  At higher levels of limb loss the prosthetic devices are heavier, as a result in order to operate the prosthetic device it requires greater energy expenditure (Datta et al., 1989; Millstein et al., 1986).  Therefore, for a person with trans-humeral amputation, performing above-shoulder maneuvers may be more challenging; thus it may influence the judgments of the upper limb prosthetic experts in selecting the type of prostheses.  4.5 Prescription Protocol for Upper Limb Prostheses  From the literature review, it suggested that there are many factors to consider in the selection of an appropriate prosthesis for an individual with upper limb amputation including the amputee’s associated diseases and injuries, medications, ADLs, recreational and vocational needs, psychosocial, accessible medical and technical support for prosthetic fitting and maintenance, physical condition (e.g. muscle strength, range of motion, amputation level), residual limb condition (May, 2002; Meier, 2004; Godfrey, 1990; Esquenazi, 2004), and patient’s preferences (e.g. comfort, cosmetic, function) (Sears, 1991). Therefore, the proposed standard prescription protocol for upper limb prostheses in this  96 study also takes these factors into account.  The proposed prescription protocol for upper limb prostheses is included in Appendix C.  4.5.1 Overview of the Prescription Protocol Appendix C is the proposed prescription protocol for upper limb prostheses which can be used to assist the practitioners for upper limb amputees in prescribing the upper limb prostheses and prosthetic components that meet the patient’s needs.  The prescription protocol is divided into 4 parts, which are: • Part 1: Clinical History and Patient's Needs – “Part 1” aims to gather the patient’s information as well as to assess the patient’s expectations, functional needs, and preferences. This part contains general demographic, health related, social information, prosthetic use, functional status, and patient’s goals and expectations.  It also contains an “Activities and Preferences Questionnaire”. The information gathered from this questionnaire will be used together with the proposed scoring system in Part 3 of the prescription protocol. • Part 2: Physical Assessment and Psychosocial Evaluation – From the review literature, both physical and psychosocial status play important roles in prosthetic prescription.  Therefore, “Part 2” aims for the practitioner to perform physical assessment of the patient’s sound limb and residual limb as well as the psychosocial evaluation. • Part 3: Type of Prosthesis Recommendation – In “Part 3”, the practitioner will make the recommendation on the type of prosthesis.  The practitioner will used  97 the proposed scoring systems to assist in selecting an appropriate prosthesis that meet the needs of the patient based on the information from “Part 1A.1” and physical assessment in “Part 2”.  The proposed scoring systems and an example of how to utilize it will be explained in details in Section 4.5.2.  In order to make the final recommendation of an appropriate type of prosthesis, the practitioner will also have to consider other factors including patient’s preferences in “Part 1A.2” and residual limb’s condition and EMG signal from “Part 2”. • Part 4: Prosthetic Prescription – “Part 4” is divided into 2 sub-parts, “Part 4A: body-powered prosthetic prescription” and “Part 4B: myoelectric prosthetic prescription”.  Based on the recommendation in “Part 3”, the practitioner will then prescribe the prosthetic components that meet the patient’s needs.  From the literature review, the cost associated with myoelectric prosthesis is high and yet the rejection rates are still high.  Therefore, it might be more cost-effective if a test fitting of myoelectric prosthesis can be provided to the patients before prescribing the actual one.  Test fitting of myoelectric prostheses will allow the patients to try out if this type of prosthesis actually suits them.  Therefore, this prescription protocol proposed to have a section on test fitting protocol for myoelectric prostheses.  4.5.2 Scoring System in the Prescription Protocol   The scope of this study was to develop a scoring system in the prescription protocol for upper limb prostheses, specifically focusing on vocational needs of the amputees.  Five  98 selected factors (i.e. “gross body movements of shoulder, upper arm and chest”, “work condition”, “lifting heavy objects”, “grip force”, and “performing above-shoulder maneuvers”) were included in the factorial surveys that employed in this preliminary study. In order to select an appropriate prosthetic device, the indication and contraindication criteria for each type of the prostheses should be considered and these criteria will be discussed next. A fundamental requirement for the use of body-powered prostheses is that the amputees must have sufficient gross body movements of shoulder, upper arm and chest. Thus, myoelectric prostheses will be more suitable for the amputees with limited gross body movements of shoulder, upper arm and chest.  In addition, for most body-powered prostheses, the functional envelope is limited to a relatively small area above the waist, and below shoulder (Brenner, 1992).   On the contrary, the major advantages of myoelectric prostheses include the ability to be used in all planes of arm movement and stronger prehension force over the body-powered prostheses (LeBlanc, 1988).  Therefore, the myoelectric limb will be the preferred type of prostheses for individuals with upper limb amputation who frequently perform above-shoulder maneuvers and need high grip force in performing tasks.  However, one of the contraindications in prescribing myoelectric prostheses is frequently lifting heavy objects.   It has been asserted that body-powered prostheses are typically recommended for those involved in wet and dirty or physically demanding work condition, while those who involved in dry and light duty work condition are likely to be recommended with myoelectric prostheses (Kejlaa, 1993; Millstein et al., 1986; Silcox, et al., 1993).  99 After the discussions about the indication and contraindication criteria to select an appropriate type of prostheses mentioned above, the development of a scoring system in the prescription protocol for upper limb prostheses will be described next.  The results from the factorial survey analysis provided the standardized regression coefficients (β) which indicate the relative importance of each dimension (factor).  To develop a scoring system in the prescription protocol, it started with calculating β 2 for each factor.  Each β 2 could be interpreted as the proportion of the variation in Y (dependent variable) accounted for by each dimension, and ∑ 2β would equal to R2 (Rossi & Anderson, 1982).  Then, the weight of each factor was determined by normalizing each β 2 and ∑ 2β ; that is to transform the values of β 2 and ∑ 2β into a range of 0 to 1.  The proposed scoring system in the prescription protocol would be based on the weight of each factor and the indication criteria in selecting the body-powered and myoelectric prostheses.  Table 4.11 and 4.12 presents the proposed scoring systems in the prescription protocol for trans-radial and trans-humeral amputation, respectively. Table 4.11 Scoring system for trans-radial amputation  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient  0.003 Limited 2. Work condition 0.962 Heavy duty  0.962 Light duty 3. Lifting heavy objects 0.014 Frequently  0.014 Rarely 4. Grip force 0.020 Low  0.020 High 5. Perform above- shoulder maneuvers 0.001 Rarely  0.001 Frequently Total 1 ∑(Wt. x Score)  1 ∑(Wt. x Score)  100 Table 4.12 Scoring system for trans-humeral amputation  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient  0.003 Limited 2. Work condition 0.874 Heavy duty  0.874 Light duty 3. Lifting heavy objects 0.086 Frequently  0.086 Rarely 4. Grip force 0.002 Low  0.002 High 5. Perform above- shoulder maneuvers 0.035 Rarely  0.035 Frequently Total 1 ∑(Wt. x Score)  1 ∑(Wt. x Score)  Table 4.13 is an example of how to utilize the proposed scoring system.  From the case example, for the level of each factor that matches the indication criteria in selecting each type of prosthesis, the score of “1” is assigned; if it does not match with the indication criteria, the score of ‘0’ is assigned.  For instance, from a statement in the case example which stated that “He has sufficient gross body movements of the shoulder, upper arm, and chest”, the level sufficient of “gross body movements of the shoulder, upper arm, and chest” factor matches the indication criteria for body-powered prostheses.  Thus, in the “gross body movements of shoulder, upper arm and chest” factor, the score of ‘1’ is assigned under the body-powered column and the score of ‘0’ is assigned under the myoelectric column.  The matching-and-assigning-score procedure is repeated for all five factors.  Then, multiply the assigned score for each factor by the weight of the corresponding factor and add them all up to get the total score.  From the case example, the total score of body-powered is 0.04, and myoelectric is 0.96.  The total scores which are obtained from the proposed scoring system  101 in the prescription protocol suggest that the recommended type of prosthesis for this case example is the myoelectric prosthesis. Table 4.13 Example of how to utilize the proposed scoring system            4.5 Conclusion A standard “Prescription Protocol for Upper Limb Prostheses” was proposed.  The prescription protocol is divided into 4 parts, which are: Part 1: Clinical History and Patient's Needs; Part 2: Physical Assessment and Psychosocial Evaluation; Part 3: Type of Prosthesis Recommendation; and Part 4: Prosthetic Prescription.  With the aim to develop a scoring system in the prescription protocol for upper limb prostheses, this study used the factorial survey as a research method.  The factorial survey is a method that can be used to Case Example: A patient with an upper limb amputation is hoping to return to work. He has sufficient gross body movements of the shoulder, upper arm, and chest. He is required to work in a light duty work condition most of the time. His work rarely involves lifting heavy objects. High grip force is expected in gripping and moving objects. He rarely needs to perform above-shoulder maneuvers.  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient 1 0.003 Limited 0 2. Work condition 0.962 Heavy duty 0 0.962 Light duty 1 3. Lifting heavy objects 0.014 Frequently 0 0.014 Rarely 1 4. Grip force 0.020 Low 0 0.020 High 1 5. Perform above-shoulder maneuvers 0.001 Rarely 1 0.001 Frequently 0 Total 1 ∑(Wt. x Score) 0.004 1 ∑(Wt. x Score) 0.996  102 assist in the assessment of upper limb prosthetic experts’ judgments and the factors that influence these judgments.  Five dimensions (factors) that contribute to the selection of the types of upper limb prosthetic devices were selected for vignette construction: gross body movements of shoulder, upper arm and chest; work condition; lifting heavy objects; grip force; and performing above-shoulder maneuvers.  The findings suggested that “work condition” is the most critical factor that influence the judgments of the upper limb prosthetic experts participated in this study in making the selection of prosthetic devices. The findings from the factorial survey analysis were used to develop scoring systems that can be used to assist in selecting the appropriate type of prosthesis for trans-radial and trans-humeral amputation. The findings from this study suggested that the factorial survey is versatile and can be used to aid in the development of a scoring system in the prescription protocol. However, it should be noted that this is a preliminary study.  There are several limitations of this scoring system which include: • The number of participants in the factorial survey was small.  Therefore, this presents the statistical limitation of the proposed scoring system in the prescription protocol. • Lack of a pilot study.  In this study the factorial surveys were only conducted with a small group of prosthetists who are the experts in upper limb prostheses.  The challenge was that there are limited number of upper limb prosthetic experts who have enough experiences in prescribing both body-powered and myoelectric prostheses.  103 • The application of the scoring system in the proposed prescription protocol is still limited.  A more representative group of participants (i.e. prosthetists, occupational therapist, physical therapist, upper limb amputees) may change the weight associated with each factor in the scoring system. • Although there are many other factors that contribute to the selection of the type of prosthesis, in this preliminary study only five factors related to the selection of the type of prostheses were chosen.  This was because these are the factors that can be assessed objectively.  Moreover, after the scoring system was developed as part of the prescription protocol for upper limb prostheses, it is important to evaluate its effectiveness in recommending an appropriate prosthesis.  Due to the limited number of upper limb amputees each year, the method that will be used to evaluate the scoring system is via retrospective information from patient files.  The five factors chosen in this preliminary study were also based on the information that is available in the patient files.  Therefore, more factors relating to the selection of an appropriate type of prosthesis (e.g., reliability, weight, comfort, cost) should also be included. It is important to evaluate the effectiveness of the proposed scoring system in recommending an appropriate prosthesis.  Thus, in the next chapter (Chapter 5), the evaluation of the proposed scoring system will be performed.  104     Chapter 5   Evaluation of the Scoring System   In the previous chapter (Chapter 4), the standard prescription protocol for upper limb prostheses has been proposed.  The proposed prescription protocol is divided into 4 parts which are “Part 1: Patient I: Clinical History and Patient's Needs”, “Part 2: Physical Assessment and Psychosocial Evaluation”, “Part 3: Type of Prostheses Recommendation”, and “Part 4: Prosthetic Prescription”.  “Part 1” intends to gather patient’s information such as cause of amputation, occupation, and expectations as well as assessing patient’s needs and preferences”.  “Part 2” is for the assessment of the limb conditions as well as the psychosocial status. “Part 3” contains the proposed scoring systems for trans-radial and trans-amputation which were developed from the factorial survey analysis in Chapter 4. These scoring systems aim to be used as tools to assist in selecting an appropriate type of upper limb prosthesis for the amputees.  “Part 4” is the part that the practitioner will prescribe prosthetic components that meet the needs of the amputees. The main purpose of this chapter is to evaluate the effectiveness of the proposed scoring systems for trans-radial and trans-humeral amputation.  However, it should be pointed out that, from the review literature in Chapter 2, only about 8% of all amputations  105 involve upper limb (Ziegler-Graham et al., 2008) and each year there are only a small number of new cases of upper limb amputations compare to the lower limb amputations. Moreover, currently, in most cases, the new amputees are usually prescribed with a body- powered prosthesis and they will have to use it for at least about a year before considering a myoelectric prosthesis.  Thus, in order to evaluate the effectiveness of the proposed scoring systems in the prescription protocol, the retrospective information from patient files is used. Twenty eight anonymous patient files of individuals who had undergone upper limb amputation from the year 2004 to 2010 were provided by the Workers Compensation Board of British Columbia (WorkSafeBC) which is the organization that responsible for providing compensation to the workers who suffered a work-related injury.  After reviewing all 28 anonymous patient files thoroughly, only nine selected patient files can be used for the evaluation of the proposed scoring systems.  The inclusion criteria for the selected patient files included: • Individuals with work-related upper limb amputation. • Individuals with trans-radial and trans-humeral amputation. • Individuals who have been prescribed with an upper limb prosthesis for more than one year. • Individuals who return to work after upper limb amputation. • Individuals who use their prosthesis regularly at work. • Individuals whose files contain record on prosthetic use consistently from the date of amputation until November, 2011.   106 This chapter will start with presenting the summary of anonymous cases’ characteristics, and occupation and causes of amputation.  Next, the summary of anonymous cases’ expectation and psychosocial functioning will be presented because these factors influence the prosthetic acceptance of the amputees.  Then, the evaluation of the effectiveness of the proposed scoring systems for trans-radial and trans-humeral amputation will be presented.  Finally, the conclusion of the findings from the evaluation of the scoring system will be discussed.  5.1 Anonymous Cases’ Characteristics Nine case reports that met the inclusion criteria were selected from the WorkSafe BC’s patient files for the evaluation of the proposed scoring systems.  Table 5.1 presents the cases’ characteristics from the selected case reports.  Eight out of nine cases were amputated on their dominant side.  Regarding the level of amputation, there are five patients with trans-radial amputation and four individuals with trans-humeral amputation.  Table 5.1   Cases’ Characteristics  Case Dominant Side Amputated Side Level of Amputation 1 Right Left Trans-radial 2 Ambidextrous Left Trans-radial 3 Right Right Trans-radial 4 Right Right Trans-radial 5 Right Right Trans-radial 6 Left Left Trans-humeral 7 Right Right Trans-humeral 8 Right Right Trans-humeral 9 Right Right Tran-humeral    107 For this study, all nine selected cases use their prostheses regularly.  However, it should be pointed out that eight out of nine cases were amputated on their dominant side. This finding is consistent with other studies (Datta & Ibottson, 1991; Datta et al., 1989; Wright et al., 1995) which reported that successful prosthetic use was associated with loss of the dominant hand.  5.2 Occupations and Causes of Amputation Table 5.2 presents the summary of occupations before amputation, after amputation and causes of amputation.  The findings from the case reports show that prior to amputation, the occupations that the amputees were employed included machining, processing, and construction.  Three out of nine cases returned to the same job but less heavy than their job prior to amputation.  The rest of the cases had to change their job after amputation.  These findings are in agreement with other studies which found that amputees returned to a job that was less heavy than their job prior to the accident (Millstein et al., 1985) and the amputees had to change their jobs after amputation (Burger et al., 2007; Davidson, 2002; Jones & Davidson, 1995; Millstein et al., 1985).  5.3 Expectation and Psychosocial Functioning Both patient’s expectation and psychosocial functioning are the factors that influence prosthetic acceptance of the prosthetic users.  Since all nine selected cases use their prostheses regularly, it is of interest to make an observation regarding their expectation and psychosocial functioning.    Therefore, the information about expectation and psychosocial functioning was extracted from the patient files.  108 Table 5.2   Summary of occupations before amputation, after amputation and causes of amputation  Case Occupation before Amputation Occupation after amputation Causes of Amputation 1 Carpenter Carpenter The worker was involving in a work- related accident. 2 Production worker Work in his orchard The worker sustained a saw injury to the left forearm. 3 Metal Sorter Labourer in recycling yard The worker was involved in a work related accident where his right hand got caught in a conveyor belt. 4 Laborer Loader operator The worker was attempting to clear out an asphalt jam at the opening of a large silo.  The silo gate closed unexpectedly striking the worker’s right arm. 5 Loader operator. Loader operator The worker was involved in a work related accident where his right hand got caught in a feed roll machine. 6 Operated a concrete cutting business Fisherman The worker was working at a job site cutting some concrete along some steel bars.  Someone working up higher on a forklift dropped 3000 pounds of angle iron on him. 7 Loader operator Loader operator The worker was cleaning rocks from a conveyor when his right arm became caught in a pulley. 8 Waste controller Load mover The worker was checking a machine when his clothing got caught and his arm pulled into the machine. 9 Clean up person Youth coordinator The worker was cleaning a machine when her coat got caught and her arm pulled into the machine.   Table 5.3 presents the summary of patients’ expectation. In general, patients had expectation to be able to return to work and their recreational activities, and to become independent.  All nine patients were able to return to work and being able to return to work increases the sense of becoming independent.  These mean that patients’ expectation has been met.  Thus, it may contribute to the successful prosthetic use of the patients.  109 Table 5.3 Summary of expectation  Case Expectation 1 - To return to work and his recreational activities. 2 - To increase strength of the residual limb, improve his use of the prosthesis, and gain better techniques for everyday activities. 3 - To have some help in learning to cope with having an upper limb amputation on his dominant side. - To become independent in all aspects of his life. 4 - To increase and improve the use of his right upper limb. - To return to his job and his recreational activities. 5 - To increase his confidence in the prosthesis and gain much functional use from the prosthesis. - To return to work as soon as possible and able to return to some of his recreational activities. 6 - To return to work and his regular life as quickly as possible. - Obtaining a myoelectric prosthesis was top priority as he sees this as the quickest and most efficient way for him to return to work. 7 - To return to his pre-injury job with some modifications. - To be able to operate his motorcycle independently. 8 - To be able to do as many of the tasks that he used to perform. - To assist in the raising of his daughter in the same way he helped in the raising of his first three children. 9 - To become as independent as possible. - To return to some of her recreational activities.   Table 5.4 presents the summary of psychosocial functioning of the patients. Overall, even though some patients experienced psychological problem, they were still sociable.  Some of the patients were adjusted well with the accident.  Therefore, this may be another factor that related to prosthetic acceptance of the patients.       110 Table 5.4 Summary of psychosocial functioning  Case Psychosocial Functioning 1 - No upsetting dreams or disturbing images of the accident. - Planned for his future and showed minimal distress. 2 - Experienced some frustration and difficulty with accepting the prosthesis. - Enjoyed interacting with other clients who have amputations during group education/therapy sessions. 3 - Had symptoms of adjustment disorder with mixed anxiety and depressed mood. - However, he was very sociable and most likely comforted by support combined with a systematic plan towards his goals. 4 - Not experienced a psychological disorder.  An optimistic individual who is robust in dealing with stressful situations. 5 - Experienced emotional trauma based symptoms. - Had most difficulty while at home during quiet time.  However, he sees people from his work often. 6 - Actively involved with the community and with some volunteer organizations. - Adjusting well psychologically to his injury. 7 - Became upset when viewing photographs of himself before the accident. - Remained interested in activities, and his appetite was fine. 8 - Not experienced a psychological disorder.  Adjusting well to the accident, with minimal difficulties. 9 - Adjusting to her injury reasonably well. - Experienced a mixture of subclinical depressive, anxiety, anger and pain symptoms.  Had a good support system.   5.4 Evaluation of the Proposed Scoring System for Trans- Radial Amputation   This section presents five case reports of individuals with trans-radial amputations and evaluates the proposed scoring system for trans-radial amputation based on the information from the patients’ files.     111 5.4.1 Case 1 Table 5.5 presents the summary of Case 1 regarding the factors related to the selection of an appropriate type of prosthesis for work.   Apply the information from Table 5.5 to the proposed scoring system for trans-radial amputation in Table 5.6.  Table 5.6 shows that, based on the proposed scoring system, the recommended type of prosthesis for Case 1 is a “body-powered prosthesis”.  Table 5.5 Case 1: Occupation after amputation, physical assessment and work description  Occupation after Amputation Physical Assessment Work Description Carpenter Sufficient gross body movements of upper extremity. - Work condition: Heavy duty - Lifting heavy objects: Frequently - Grip force: High - Performing above-shoulder maneuvers: Rarely   Table 5.6 Scoring system for trans-radial amputation: Type of prosthesis recommendation for Case 1  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient 1 0.003 Limited 0 2. Work condition 0.962 Heavy duty 1 0.962 Light duty 0 3. Lifting heavy objects 0.014 Frequently 1 0.014 Rarely 0 4. Grip force 0.020 Low 0 0.020 High 1 5. Perform above- shoulder maneuvers 0.001 Rarely 1 0.001 Frequently 0 Total 1 ∑(Wt. x Score) 0.98 1 ∑(Wt. x Score) 0.02   112 5.4.2 Case 2 Table 5.7 presents the summary of Case 2 regarding the factors related to the selection of an appropriate type of prosthesis for work.   Apply the information from Table 5.7 to the proposed scoring system for trans-radial amputation in Table 5.8.  Table 5.8 shows that, based on the proposed scoring system, the recommended type of prosthesis for Case 2 is a “body-powered prosthesis”.  Table 5.7 Case 2: Occupation after amputation, physical assessment and work description  Occupation after Amputation Physical Assessment Work Description Work in his orchard. Sufficient gross body movements of upper extremity. - Work condition: Heavy duty - Lifting heavy objects: Rarely - Grip force: Low - Performing above-shoulder maneuvers: Rarely    Table 5.8 Scoring system for trans-radial amputation: Type of prosthesis recommendation for Case 2  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient 1 0.003 Limited 0 2. Work condition 0.962 Heavy duty 1 0.962 Light duty 0 3. Lifting heavy objects 0.014 Frequently 0 0.014 Rarely 1 4. Grip force 0.020 Low 1 0.020 High 0 5. Perform above- shoulder maneuvers 0.001 Rarely 1 0.001 Frequently 0 Total 1 ∑(Wt. x Score) 0.996 1 ∑(Wt. x Score) 0.014   113 5.4.3 Case 3 Table 5.9 presents the summary of Case 3 regarding to the factors related to the selection of an appropriate type of prosthesis for work.  Apply the information from Table 5.9 to the proposed scoring system for trans-radial amputation in Table 5.10.  Table 5.10 shows that, based on the proposed scoring system, the recommended type of prosthesis for Case 3 is a “body-powered prosthesis”.  Table 5.9 Case 3: Occupation after amputation, physical assessment and work description  Occupation after Amputation Physical Assessment Work Description Labourer in aluminum recycling yard Sufficient gross body movements of upper extremity. - Work condition: Heavy duty - Lifting heavy objects: Frequently - Grip force: High - Performing above-shoulder maneuvers: Rarely   Table 5.10 Scoring system for trans-radial amputation: Type of prosthesis recommendation for Case 3  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient 1 0.003 Limited 0 2. Work condition 0.962 Heavy duty 1 0.962 Light duty 0 3. Lifting heavy objects 0.014 Frequently 1 0.014 Rarely 0 4. Grip force 0.020 Low 0 0.020 High 1 5. Perform above- shoulder maneuvers 0.001 Rarely 1 0.001 Frequently 0 Total 1 ∑(Wt. x Score) 0.98 1 ∑(Wt. x Score) 0.02   114 In this case, the patient was successfully re-integrating back to work where he was responsible for a variety of manual labor oriented tasks.  He has two body-powered prostheses due to the heavy demands placed on his body-powered prostheses and the continuing physical nature of the patient’s job.  5.4.4 Case 4 Table 5.11 presents the summary of Case 4 regarding to the factors related to the selection of an appropriate type of prosthesis for work.  Apply the information from Table 5.11 to the proposed scoring system for trans-radial amputation in Table 5.12.  Table 5.12 shows that, based on the proposed scoring system, the recommended type of prosthesis for Case 4 is a “myoelectric prosthesis”. In this case, as the user was using his conventional body-powered prosthesis, he was getting some intermittent neck pain.  He enquired with regards to a myoelectric prosthesis, which would reduce the amount of harnessing which he finds at time causes him discomfort and limits his range of motion.  He did not really use his body-powered prosthesis at all, but used his myoelectric devices consistently.  He has become a full time myoelectric user in his employment as well as in his ADL.  Table 5.11 Case 4: Occupation after amputation, physical assessment and work description  Occupation after Amputation Physical Assessment Work Description Loader operator Sufficient gross body movements of upper extremity. - Work condition: Light duty - Lifting heavy objects: Rarely - Grip force: Low - Performing above-shoulder maneuvers: Rarely   115 Table 5.12 Scoring system for trans-radial amputation: Type of prosthesis recommendation for Case 4  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient 1 0.003 Limited 0 2. Work condition 0.962 Heavy duty 0 0.962 Light duty 1 3. Lifting heavy objects 0.014 Frequently 0 0.014 Rarely 1 4. Grip force 0.020 Low 1 0.020 High 0 5. Perform above- shoulder maneuvers 0.001 Rarely 1 0.001 Frequently 0 Total 1 ∑(Wt. x Score) 0.024 1 ∑(Wt. x Score) 0.976  5.4.5 Case 5 Table 5.13 presents the summary of Case 5 regarding to the factors related to the selection of an appropriate type of prosthesis for work.  Apply the information from Table 5.13 to the proposed scoring system for trans-radial amputation in Table 5.14.  Table 5.14 shows that, based on the proposed scoring system, the recommended type of prosthesis for Case 5 is a “myoelectric prosthesis”.  Table 5.13 Case 5: Occupation after amputation, physical assessment and work description  Occupation after Amputation Physical Assessment Work Description Loader operator Sufficient gross body movements of upper extremity. - Work condition: Light duty - Lifting heavy objects: Rarely - Grip force: Low - Performing above-shoulder maneuvers: Rarely     116 Table 5.14 Scoring system for trans-radial amputation: Type of prosthesis recommendation for Case 5  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient 1 0.003 Limited 0 2. Work condition 0.962 Heavy duty 0 0.962 Light duty 1 3. Lifting heavy objects 0.014 Frequently 0 0.014 Rarely 1 4. Grip force 0.020 Low 1 0.020 High 0 5. Perform above- shoulder maneuvers 0.001 Rarely 1 0.001 Frequently 0 Total 1 ∑(Wt. x Score) 0.024 1 ∑(Wt. x Score) 0.976    5.5 Evaluation of the Proposed Scoring System for Trans- Humeral Amputation This section presents four case reports of individuals with trans-humeral amputations and evaluates the proposed scoring system for trans-radial amputation based on the information from the patients’ files.  5.5.1 Case 6 Table 5.15 presents the summary of Case 6 regarding to the factors related to the selection of an appropriate type of prosthesis for work.  Apply the information from Table 5.15 to the proposed scoring system for trans-humeral amputation in Table 5.16.  Table 5.16 shows that, based on the proposed scoring system, the recommended type of prosthesis for Case 6 is a “body-powered prosthesis”.  117 Table 5.15 Case 6: Occupation after amputation, physical assessment and work description  Occupation after Amputation Physical Assessment Work Description Fisherman Sufficient gross body movements of upper extremity.  - Work condition: Heavy duty - Lifting heavy objects: Rarely - Grip force: Low - Performing above-shoulder maneuvers: Rarely   Table 5.16 Scoring system for trans-humeral amputation: Type of prosthesis recommendation for Case 6  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient 1 0.003 Limited 0 2. Work condition 0.874 Heavy duty 1 0.874 Light duty 0 3. Lifting heavy objects 0.086 Frequently 0 0.086 Rarely 1 4. Grip force 0.002 Low 1 0.002 High 0 5. Perform above-shoulder maneuvers 0.035 Rarely 1 0.035 Frequently 0 Total 1 ∑(Wt. x Score) 0.914 1 ∑(Wt. x Score) 0.086    In this case, the patient was initially prescribed with a body-powered prosthesis and later with a hybrid prosthesis.  However, since he has become a fisherman, the patient requested for a body-powered prosthesis because he found myoelectric prosthetic device was too heavy and he needed a prosthesis that can be used around water.     118 5.5.2 Case 7 Table 5.17 presents the summary of Case 7 regarding to the factors related to the selection of an appropriate type of prosthesis for work.  Apply the information from Table 5.17 to the proposed scoring system for trans-humeral amputation in Table 5.18.  Table 5.18 shows that, based on the proposed scoring system, the recommended type of prosthesis for Case 7 is a “myoelectric  prosthesis”.  Table 5.17  Case 7: Occupation after amputation, physical assessment and work description  Occupation after Amputation Physical Assessment Work Description Loader operator Sufficient gross body movements of upper extremity. - Work condition: Light duty - Lifting heavy objects: Rarely - Grip force: Low - Performing above-shoulder maneuvers: Rarely    Table 5.18 Scoring system for trans-humeral amputation: Type of prosthesis recommendation for Case 7  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient 1 0.003 Limited 0 2. Work condition 0.874 Heavy duty 0 0.874 Light duty 1 3. Lifting heavy objects 0.086 Frequently 0 0.086 Rarely 1 4. Grip force 0.002 Low 1 0.002 High 0 5. Perform above-shoulder maneuvers 0.035 Rarely 1 0.035 Frequently 0 Total 1 ∑(Wt. x Score) 0.04 1 ∑(Wt. x Score) 0.96  119 In this case, with the use of body-powered prosthesis that was initially prescribed, there was problem reported in use of the prosthetic arm above shoulder level.  At the end of a workday, the right shoulder was fairly uncomfortable and there was irritation from the harness which went over and around the left arm.  Thus, the user was later prescribed with a myoelectric prosthesis.   5.5.3 Case 8 Table 5.19 presents the summary of Case 8 regarding to the factors related to the selection of an appropriate type of prosthesis for work.  Apply the information from Table 5.19 to the proposed scoring system for trans-humeral amputation in Table 5.20.  Table 5.20 shows that, based on the proposed scoring system, the recommended type of prosthesis for Case 8 is a “myoelectric  prosthesis”. In this case, he was prescribed with a myoelectric prosthesis because it provides more accurate control over the terminal device and requires less energy expenditure than operation of body-powered prosthesis does which is especially important for the high level amputee.  Table 5.19 Case 8: Occupation after amputation, physical assessment and work description  Occupation after Amputation Physical Assessment Work Description Load mover Sufficient gross body movements of upper extremity. - Work condition: Light duty - Lifting heavy objects: Rarely - Grip force: Low - Performing above-shoulder maneuvers: Rarely    120 Table 5.20 Scoring system for trans-humeral amputation: Type of prosthesis recommendation for Case 8  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient 1 0.003 Limited 0 2. Work condition 0.874 Heavy duty  0 0.874 Light duty 1 3. Lifting heavy objects 0.086 Frequently 0 0.086 Rarely 1 4. Grip force 0.002 Low 1 0.002 High 0 5. Perform above-shoulder maneuvers 0.035 Rarely 1 0.035 Frequently 0 Total 1 ∑(Wt. x Score) 0.04 1 ∑(Wt. x Score) 0.96   5.5.4 Case 9 Table 5.21 presents the summary of Case 9 regarding to the factors related to the selection of an appropriate type of prosthesis for work.  Apply the information from Table 5.21 to the proposed scoring system for trans-humeral amputation in Table 5.22.  Table 5.22 shows that, based on the proposed scoring system, the recommended type of prosthesis for Case 9 is a “myoelectric  prosthesis”.  Table 5.21 Case 9: Occupation after amputation, physical assessment and work description  Occupation after Amputation Physical Assessment Work Description Youth coordinator Sufficient gross body movements of upper extremity. - Work condition: Light duty - Lifting heavy objects: Rarely - Grip force: Low - Performing above-shoulder maneuvers: Rarely  121 In this case, one of the advantages of using the prosthesis for the user is that it helps offload the left upper limb.  She wears myoelectric prosthesis consistently because the body-powered prosthesis does not very useful to her given how difficult it is to operate.   Table 5.22 Scoring system for trans-humeral amputation: Type of prosthesis recommendation for Case 9  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient 0 0.003 Limited 1 2. Work condition 0.874 Heavy duty 0 0.874 Light duty 1 3. Lifting heavy objects 0.086 Frequently 0 0.086 Rarely 1 4. Grip force 0.002 Low 1 0.002 High 0 5. Perform above-shoulder maneuvers 0.035 Rarely 1 0.035 Frequently 0 Total 1 ∑(Wt. x Score) 0.037 1 ∑(Wt. x Score) 0.963    5.6 Conclusion Nine cases were presented.  The findings from the case reports show that prior to amputation, the occupations that the amputees were employed included machining, processing, and construction.  After the amputation, some of the cases returned to their job that was less heavy than their job prior to the accident while others had to change their jobs.  Moreover, expectation and psychosocial functioning contribute to the prosthetic use of the amputees.   In addition, the cases show that the problems related to body-powered prostheses are discomfort from harness, the limited range of motion especially at above-  122 shoulder level, and shoulder and neck pain.  The users who encountered these problems enquired for myoelectric prostheses.  It was also found that users who use body-powered prostheses for work are those who work in heavy work condition.  Moreover, for those with high level amputation, myoelectric prosthesis is the preferred type of prosthesis because it requires less energy expenditure and easier to operate than body-powered prostheses. In order to evaluate the proposed scoring system, the information associated with the five factors in the scoring system (i.e. “gross body movements of shoulder, upper arm and chest”, “work condition”, “lifting heavy objects”, “grip force”, and “performing above- shoulder maneuvers”) was extracted from the patient files.  Then, the extracted information was applied to the proposed scoring system in the prescription protocol in order to get the recommended type of prosthesis. Table 5.23 presents the level of amputation, occupation after amputation, initial prosthesis, prosthesis for work for all nine cases and the recommended prosthesis from the proposed scoring system for each case.  The results, as shown in Table 5.23, suggest that the type of prosthesis recommended for work of all nine cases matches with the recommended prosthesis from the proposed scoring system in the prescription protocol. This finding suggests that the proposed scoring systems can be used as a tool to assist in the selection of an appropriate prosthetic device.  It should be pointed out that there is still some drawback of the proposed scoring systems, i.e. “work condition” is the only key factor in determining the type of prosthesis.  However, it should be noted that this is a preliminary study.  There are still many factors to consider when selecting an appropriate type of prosthesis such as patient’s preferences regarding comfort, weight, or aesthetic that  123 can be included in the factorial survey.  Thus, further studies are needed as it may lead to improve the scoring system in selecting the type of prosthesis that meet the patient’s needs.  Table 5.23 Recommended type of prosthesis from the scoring system in the prescription protocol  Case Level of Amputation Occupation after amputation Initial prosthesis Prosthesis for work Recommended prosthesis from the scoring system 1 Lt. Transradial Carpenter Body- powered Body- powered Body-powered 2 Lt. Transradial Work in his orchard Body- powered Body- powered Body-powered 3 Rt. Transradial Labourer in recycling yard Body- powered Body- powered Body-powered 4 Rt. Transradial Loader operator Body- powered Myoelectric Myoelectric 5 Rt. Transradial Loader operator Body- powered Myoelectric Myoelectric 6 Lt. Transhumeral Fisherman Body- powered Body- powered Body-powered 7 Rt. Transhumeral Loader operator Body- powered Myoelectric Myoelectric 8 Rt. Transhumeral Load mover Body- powered Myoelectric Myoelectric 9 Rt. Transhumeral Youth coordinator Body- powered Myoelectric Myoelectric       124     Chapter 6 Conclusions and Future Work  6.1 Conclusions This study has established a method to measure friction as a function of loading rate at a typical activities of daily living.  The frictional properties of the surfaces in contact between the two commonly prescribed terminal devices (i.e. a body-powered split hook and an Otto Bock Myohand DMC VariPlus Speed®) and the gripped objects made of metal, plastic, and wood were examined.  The findings indicated that the static friction coefficients ( Sµ ) of the surfaces in contact of the body-powered split hook and that of the myoelectic hand were dependent on material properties and the loading rates.  The results suggested that the loading rates affected the frictional properties of the surfaces in contact between the terminal device and the objects, i.e. the static friction coefficients ( Sµ ) decreased as the loading rate increased.  The findings from this study suggested the necessity to consider the frictional properties in improving the design of prosthetic terminal devices and selecting an appropriate type of terminal device for the amputees.  125 Furthermore, the present study proposed a standard “Prescription Protocol for Upper Limb Prostheses”.  The prescription protocol is divided into 4 parts, which are: Part 1: Clinical History and Patient's Needs; Part 2: Physical Assessment and Psychosocial Evaluation; Part 3: Type of Prosthesis Recommendation; and Part 4: Prosthetic Prescription.  The proposed prescription protocol takes into account a variety of aspects including the amputee’s physical and psychosocial condition, functional status, goals and expectations, work condition, and preferences.  In order to have a protocol that can be used to assess the amputees’ needs in a systematic way, the scoring system which may provide a better objective approach was proposed. Factorial survey approach was used as a research method to develop scoring systems for the prescription protocol that can be used as a tool to objectively select appropriate upper limb prostheses based on the needs and conditions of the prosthetic users.  The findings suggested that “work condition” was the most critical factor that influence the judgments of the upper limb prosthetic experts in making the selection of prosthetic devices for both trans-radial and trans-humeral amputation. Moreover, the effectiveness of the proposed scoring systems in the prescription protocol for upper limb prostheses was evaluated by using the retrospective data from patient files. The results indicated that the type of prosthesis for work of all cases from the patient files matched with the recommended prosthesis from the proposed scoring system in the prescription protocol.  This suggested that the proposed scoring systems can be used as a tool to assist in the selection of an appropriate prosthetic device.    126 6.2 Recommendations for Future Work 6.2.1 Frictional Properties of Terminal Devices With regard to the frictional properties of terminal devices, there are several limitations to this study.  Firstly, this study only evaluated two types of terminal devices which are a body-powered split hook and Otto Bock Myohand DMC VariPlus Speed®. Secondly, there were only three selected types of materials that were tested, metal plastic, and wood.  On a daily basis, there are large variations that can have effects on the friction coefficients such as other types of materials, shapes roughness of the surface, hardness, and contact area.  Finally, the effect of loading rates was only examined on the three selected types of materials.  It should be pointed out that the static friction coefficients ( Sµ ) reported in this study are specific to the material properties of the objects and the lining surfaces of the terminal devices used in this study.  More understanding with regard to the frictional properties and loading rates may help to improve the design of prosthetic devices for upper limb amputees. Therefore, future research works are needed to: • Evaluate the frictional properties and the effect of loading rates on frictional properties between various materials that are used for surface lining of terminal devices and a variety of objects that are used in activities of daily living, vocational, and recreational activities.  For example, the alternative type of glove for a myoelectric hand is made of silicone.  Thus, it is of interest to evaluate its frictional properties when in contact with different types of objects that are used in activities of daily living, work-related and recreational activities. • Evaluate and compare the frictional properties of different types of terminal devices from different manufacturers.  This will provide a better understanding on whether  127 the terminal device from each manufacturer can provide different function.  For example, comparing the function between a myoelectric hand from Otto Bock and an i-limb hand from Touch Bionics when gripping different shapes of objects it would be interesting to see which type of terminal device will provide a better grip for each type of object. • Find the type of material that is suitable for the terminal device that is needed for a physical demanding job and design it as a glove to be able to put on anytime that is needed for work.  The reason behind this is that for individuals with upper limb amputations who return to heavy duty work condition, a body-powered hook is commonly used.  However, a body-powered hook can provide limited grip force. Therefore, finding the type of material that has high friction and can be used as a glove will help in providing a more stable grip when handling an object. • A study by Chan and colleagues (2012) has developed an assessment platform for myoelectric prostheses.  It is recommended that the platform should also include the measurement of slippage because in activities of daily living we have to deal with different types of objects.  In this study, a method to perform slip measurement was established and should also be included in the assessment platform.  6.2.2 Prescription Protocol for Upper Limb Prostheses With regard to the prescription protocol, the initial results from this study suggested that the factorial survey is versatile and has the potential to be used in the development of a scoring system in the prescription protocol.  However, it should be noted that this is a preliminary study and there remains further work to be carried out before a conclusive  128 prescription protocol can be obtained.  There are some limitations to this study.  This study was conducted with a limited number of convenience sample group of upper limb prosthetic experts.  Therefore, there is limitation in terms of generalizability of the study. Another limitation is that in this study the factorial survey was conducted with a small group of prosthetists.  It did not include other health care professionals such as the occupational therapists and physical therapists or the amputees themselves. Thus, the weights associated with each factor in the proposed scoring system are still not useful in clinical practice.  Further develop of the scoring system is still needed to be able to utilize the scoring system effectively in selecting an appropriate type of prostheses for the upper limb amputees.  In addition, in this preliminary study only five factors related to the selection of the type of prostheses were included in the scoring system.  Other parameters associated with the selection of the prosthetic device such as weight, cost, grip function, comfort have not been included in this study. Therefore, further researches should also consider the following issues: • The factorial survey should be conducted with a larger sample size and a more representative group of participants (i.e. prosthetists, occupational therapists, physical therapists, and upper limb amputees).  Different perspectives from  various group of participants will assist in developing a more comprehensive scoring system for the prescription protocol.  In addition, additional research needs to include other parameters (e.g. comfort, grip function, aesthetic, weight, and cost) in the factorial survey.  This can be done by developing vignettes and inviting the professionals from various disciplines to participate in the factorial survey.  129 • Expand the prescription protocol. The slippage or the frictional properties of the terminal devices should be included as a technical parameters in the protocol. 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Rehabil., 89, 422-429.   146    Appendix A  List of Vignettes   147 Vignettes Vignette Gross body movement Work Condition Lift heavy objects Grip force Perform Above shoulder maneuvers 1 Sufficient Light duty Rarely High Rarely 2 Sufficient Light duty Rarely High Frequently 3 Sufficient Light duty Rarely Low Rarely 4 Sufficient Light duty Rarely Low Frequently 5 Sufficient Light duty Frequently High Rarely 6 Sufficient Light duty Frequently High Frequently 7 Sufficient Light duty Frequently Low Rarely 8 Sufficient Light duty Frequently Low Frequently 9 Sufficient Heavy duty Rarely High Rarely 10 Sufficient Heavy duty Rarely High Frequently 11 Sufficient Heavy duty Rarely Low Rarely 12 Sufficient Heavy duty Rarely Low Frequently 13 Sufficient Heavy duty Frequently High Rarely 14 Sufficient Heavy duty Frequently High Frequently 15 Sufficient Heavy duty Frequently Low Rarely 16 Sufficient Heavy duty Frequently Low Frequently 17 Limited Light duty Rarely High Rarely 18 Limited Light duty Rarely High Frequently 19 Limited Light duty Rarely Low Rarely 20 Limited Light duty Rarely Low Frequently 21 Limited Light duty Frequently High Rarely 22 Limited Light duty Frequently High Frequently 23 Limited Light duty Frequently Low Rarely 24 Limited Light duty Frequently Low Frequently 25 Limited Heavy duty Rarely High Rarely 26 Limited Heavy duty Rarely High Frequently 27 Limited Heavy duty Rarely Low Rarely 28 Limited Heavy duty Rarely Low Frequently 29 Limited Heavy duty Frequently High Rarely 30 Limited Heavy duty Frequently High Frequently 31 Limited Heavy duty Frequently Low Rarely 32 Limited Heavy duty Frequently Low Frequently  148    Appendix B  Example of Factorial Survey  149 Upper Limb Prosthesis Survey Please rate the appropriateness for the patient to be fitted with a myoelectric prosthesis in each case on a scale of 1 (Not appropriate at all) to 9 (Very appropriate). Please choose the rating relative to other cases. Avoid choosing the extreme ratings unless it is indeed completely appropriate or inappropriate. Thank you!  Example A patient with an upper limb amputation is hoping to return to work. He has sufficient gross body movements of the shoulder, upper arm, and chest. He is required to work in a light duty work condition most of the time. His work rarely involves lifting heavy objects. High grip force is expected in gripping and moving objects. He rarely needs to perform above-shoulder maneuvers. For trans-radial amputation: In your opinion, how appropriate would it be for the patient to be fitted with a myoelectric device? Not appropriate at all                                                                                Very appropriate 1---------2--------3---------4---------5---------6---------7---------8---------9 For trans-humeral amputation: In your opinion, how appropriate would it be for the patient to be fitted with a myoelectric device?  Not appropriate at all                                                                                 Very appropriate 1---------2--------3---------4---------5---------6---------7---------8---------9  Cases Patient’s Condition and Expectation Level of Amputation Gross body movements of the shoulder, upper arm, and chest Work Condition Lifting heavy objects Grip force Perform above-shoulder maneuvers Transradial Amputation Transhumeral Amputation 1 Limited Light duty Rarely High Rarely Click here to rateClick here to rate 2 Sufficient Heavy duty Rarely Low Frequently Click here to rateClick here to rate 3 Sufficient Heavy duty Rarely Low Rarely Click here to rateClick here to rate 4 Limited Heavy duty Frequently Low Rarely Click here to rateClick here to rate 5 Sufficient Light duty Rarely Low Rarely Click here to rateClick here to rate 6 Sufficient Heavy duty Frequently Low Rarely Click here to rateClick here to rate 7 Limited Light duty Frequently High Frequently Click here to rateClick here to rate 8 Sufficient Heavy duty Frequently High Rarely Click here to rateClick here to rate 9 Sufficient Heavy duty Frequently High Rarely Click here to rateClick here to rate 10 Limited Heavy duty Frequently Low Frequently Click here to rateClick here to rate  150 11 Limited Heavy duty Frequently High Rarely Click here to rateClick here to rate 12 Sufficient Light duty Rarely High Frequently Click here to rateClick here to rate 13 Limited Light duty Frequently High Rarely Click here to rateClick here to rate 14 Limited Heavy duty Rarely Low Rarely Click here to rateClick here to rate 15 Limited Heavy duty Rarely Low Frequently Click here to rateClick here to rate 16 Sufficient Light duty Frequently High Frequently Click here to rateClick here to rate 17 Sufficient Heavy duty Rarely High Rarely Click here to rateClick here to rate 18 Sufficient Heavy duty Frequently Low Frequently Click here to rateClick here to rate 19 Sufficient Light duty Rarely Low Frequently Click here to rateClick here to rate 20 Sufficient Light duty Frequently Low Rarely Click here to rateClick here to rate   151    Appendix C  Proposed Prescription Protocol for Upper Limb Prostheses  152 Prescription Protocol for Upper Limb Prostheses  OVERVIEW The “Standard Prescription Protocol for Upper Limb Prostheses” can be used to assist the practitioners in prescribing the upper limb prostheses and prosthetic components that meet the patient’s goals and expectations.  The protocol is divided into 4 parts, which are:  PART 1: CLINCAL HISTORY AND PATIENT'S NEED: • To be completed by the patient. • Contains general demographic, health related, social information, prosthetic use, functional status, and patient’s goals and expectations. • Contains an “Activities and Preferences Questionnaire”.  The information gathered from this questionnaire will be used together with the proposed scoring system in “Part 3” of the prescription protocol.  PART 2: PHYSICAL ASSESSMENT AND PSYCHOSOCIAL EVALUATION: • To be completed by the practitioner. • Perform physical assessment and psychosocial evaluation.  PART 3: TYPE OF PROSTHESIS RECOMMENDATION: • To be completed by the practitioner. • Make the recommendation on the type of the prosthesis by using the scoring systems.  The information from the “Part 1A.1” and “Part 2” will be used along with this part.  PART 4: PROSTHETIC PRESCRIPTION: • To be completed by the practitioner. • Part 4A: Body-powered prosthetic prescription. • Part 4B: Myoelectric prosthetic prescription and test fitting protocol. • Based on the recommendation in part 3, the practitioner prescribes the prosthetic components that meet the patient’s ADL, vocational and recreational activities requirements.    153 PART 1: CLINACAL HISTORY AND PATIENT'S NEED  Date: ________________  1. General Information Name: __________________________________ Date of Birth: __________  Age: ______ Sex:      Male       Female                                  Height: ________    Weight: _________ WorkSafeBC Claim Number: ____________   Personal Health Number : ______________ Address: _________________________________________________________________ Phone (H): _________________________      Phone (W): __________________________ Amputation Side:          Left                               Right                Bilateral Level of Amputation:    Wrist disarticulation     Trans-radial     Elbow disarticulation  Trans-humeral           Shoulder disarticulation  Other _________________________ Date of Amputation: ____________________________   Dominant Side: _____________ Cause of Amputation: _______________________________________________________ 2. Health Related Information Have you ever been diagnosed with the following conditions?  Circulation problems                   Heart problems               Diabetes  High blood pressure                    Rheumatoid arthritis       Other arthritis conditions  Muscle pain                                 Back pain                        Depression  Other __________________________________________________________________ Other relevant injuries: ______________________________________________________ Medication(s): _____________________________________________________________ Allergies: _________________________________________________________________ 3. Social Information Living Status:          Live alone                      Live with assistance from others Were you working prior to your amputation?   Yes                No - If yes, what was your occupation? ____________________________________________ Are you currently working?                              Yes                No - If yes, what is your occupation? ______________________________________________ How many hours/day? ___________________  How many days/week? ________________ - If no, do you plan to go back to work?           Yes                No   154 4. Prosthetic Use Are you currently wearing a prosthesis?            Yes                No If yes, please identify the type of prosthesis ______________________________________            how many hours/day do you wear your prosthesis?      _______  hours/day            how many days/week do you wear your prosthesis?     _______  days/week 5. Functional Status Please list the functional activities that you are able to perform: _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Please list the functional activities that you have difficulty to perform: _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6. Goals and Expectations Activities of Daily Living (ADLs): ____________________________________________ _________________________________________________________________________ _________________________________________________________________________ Vocational Activities: _______________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Leisure Activities: __________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 7. Other Comments _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________  155 PART 1A: ACTIVITIES AND PREFERENCES QUESTIONNAIRE  1A.1   Activities  Please answer the following questions:  1. What type of work condition do you expect to work in most of the time using your prosthesis?   Light duty                    Heavy duty  2. How often do you expect to lift heavy objects with your prosthesis?  Rarely                          Frequently 3. How much of grip force do you expect from the prosthesis to lift and/or carry objects most of the time?  Low                             High 4. How often do you expect to perform above-shoulder maneuvers using your prosthesis?  Rarely                          Frequently   1A.2 Preferences in Selecting Prosthesis  Please rank the following factors relating to your preference in selecting a prosthesis on a scale of 1 = “Most preference” to 5 = “Least preference”.  Factors Ranking Aesthetic Function Comfort (weight of the prosthesis) Comfort (harness) Easy access to maintenance         156 PART 2: Physical Assessment and Psychosocial Evaluation  Name: ___________________________________________________  Date: __________   I   Contralateral Limb (Sound Limb):                    Left              Right          N/A 1.   Sensation - Light touch  Normal         Decreased              Increased - Pin Prick      Normal         Decreased              Increased 2.   Range of Motion (ROM) & Muscle Strength Joint Muscle Group Active ROM (Degrees) Passive ROM (Degrees) Muscle Strength (Grade 0 -5) Shoulder Flexion Extension Abduction Adduction Internal Rotation External Rotation Elbow Flexion Extension Pronation Supination Wrist Flexion Extension Radial Deviation Ulnar Deviation          157 II  Residual Limb:                    Left              Right          Bilateral  1.   Length of the residual limb  Left:  _____cm.               Right: ______ cm.  2.   Circumference of the residual limb  Left:  _____cm.               Right: ______ cm.  3.   Edema   None             Mild               Moderate          Severe  Pitting           +1                   +2                     +3 4.   Shape of the residual limb  Cylindrical    Conical          Bulbous  Other ________________________________________ 5.   Scar  Healed              Adherent        Invaginated     Flat  Other ________________________________________ 6.   Sensation                     - Light touch  Normal          Decreased        Increased - Pin Prick      Normal          Decreased        Increased 7.  Residual Limb Pain  - Does the patient have pain in the residual limb(s)?    Yes  No (If no, continue to question 2)    If yes, where is the pain? __________________________    Is this pain constant:      Yes         No - On a scale of 0-10 (0 = no pain, 10 = worst pain), what is the pain level? _______________ - What makes it worse? ____________________________ - What does the patient do to relieve the pain? ________________________________________________  158  8.   Phantom Pain  - Does the patient have pain in the part of arm(s) that is/are no longer there?     Yes        No (If no, continue to question 3)     If yes, where is the pain? _________________________     Is this pain constant:         Yes        No - On a scale of 0-10 (0 = no pain, 10 = worst pain), what is the pain level? _______________ - What makes it worse? ____________________________ - What does the patient do to relieve the pain? ________________________________________________ 9.   Phantom Feeling  - Do you have feeling in the part of your arm(s) that is/are no longer there?     Yes        No (If no, continue to question 4)    If yes, where is the feeling? ________________________    Is this feeling constant:      Yes        No - Describe the feeling ______________________________  159  10.   Range of Motion (ROM) & Muscle Strength Joint Muscle Group Active ROM (Degrees) Passive ROM (Degrees) Muscle Strength (Grade 0 – 5) Shoulder Flexion Extension Abduction Adduction Internal Rotation External Rotation Elbow Flexion Extension Pronation Supination Wrist Flexion Extension Radial Deviation Ulnar Deviation  11.  EMG signal   Nondetectable                  Insufficient and not trainable  Insufficient but trainable  Sufficient  12.  EMG Site  Identify:_________________________________________ ________________________________________________  13.  EMG signal separation  ________________________________________________  13.  Psychosocial        Functioning  ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________  160 PART 3: TYPE OF PROSTHESIS RECOMMENDATION Name: ___________________________________________________  Date: __________  Part 3: Type of prosthesis recommendation is divided into 4 sections: 3.1 Scoring system; 3.2 Patient’s preference; 3.3 Residual limb’s condition; 3.4 EMG signal.  3.1 Scoring System  Example of how to utilize the scoring system:  From the case example, for the level of each factor that matches the indication criteria for each type of prosthesis, the score of “1” is assigned; if it does not match with the indication criteria, the score of ‘0’ is assigned  Case Example: A patient with an upper limb amputation is hoping to return to work. He has sufficient gross body movements of the shoulder, upper arm, and chest. He is required to work in a light duty work condition most of the time. His work rarely involves lifting heavy objects. High grip force is expected in gripping and moving objects. He rarely needs to perform above-shoulder maneuvers.  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient 1 0.003 Limited 0 2. Work condition 0.962 Heavy duty 0 0.962 Light duty 1 3. Lifting heavy objects 0.014 Frequently 0 0.014 Rarely 1 4. Grip force 0.020 Low 0 0.020 High 1 5. Perform above-shoulder maneuvers 0.001 Rarely 1 0.001 Frequently 0 Total 1 ∑(Wt. x Score) 0.004 1 ∑(Wt. x Score) 0.996     161  3.1.1 Base on the information from Part 1A “Activities and Preferences Questionnaire” section 1A.1 (Activities), and Part 2 “Physical Assessment and Psychosocial Evaluation” assign the score of “1” for each response that corresponds to the indication criteria for body-powered and myoelectric prostheses in the following tables.  Trans-Radial Amputation  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient  0.003 Limited 2. Work condition 0.962 Heavy duty  0.962 Light duty 3. Lifting heavy objects 0.014 Frequently  0.014 Rarely 4. Grip force 0.020 Low  0.020 High 5. Perform above- shoulder maneuvers 0.001 Rarely  0.001 Frequently Total 1 ∑(Wt. x Score)  1 ∑(Wt. x Score)  Trans-Humeral Amputation  Factors Body-Powered Prostheses Myoelectric Prostheses Weight (Wt.) Indication Criteria Score  Weight (Wt.) Indication Criteria Score 1. Gross body movements of upper extremity 0.003 Sufficient  0.003 Limited 2. Work condition 0.874 Heavy duty  0.874 Light duty 3. Lifting heavy objects 0.086 Frequently  0.086 Rarely 4. Grip force 0.002 Low  0.002 High 5. Perform above-shoulder maneuvers 0.035 Rarely  0.035 Frequently Total 1 ∑(Wt. x Score)  1 ∑(Wt. x Score)  162 3.2 Patient’s preferences Based on the information from Part 1A “Activities and Preferences Questionnaire” section 1A.2 (Preferences in Selecting Prosthesis) Ranking  Factors 1 2 3 4 5  3. 3 Residual limb’s condition Base on the information from Part 2 “Physical Assessment and Psychosocial Evaluation”, the residual limb condition is:  Ready to be fitted with myoelectric prosthesis ---  continue to section 3.4  Not ready to be fitted with myoelectric prosthesis --- go to PART 4A: Body-powered prosthesis prescription  3.4 EMG signal  Base on the information from Part 2 “Physical Assessment and Psychosocial Evaluation”, EMG signal is:   Nondetectable Go to PART 4A: Body-powered prosthesis prescription  Insufficient and not trainable  Insufficient but trainable Go to PART 4B: Myoelectric prosthesis prescription  Sufficient  Prosthetist’s Recommendation:     Body-powered prosthesis  Myoelectric prosthesis Remarks: _________________________________________________________________ _________________________________________________________________________ Name of prosthetist: ________________________________________________________ Prosthetist signature: ______________________________________ Date: ____________ Clinic name: ______________________________________________________________ Clinic address: ____________________________________________________________ Phone number: _________________________   Fax number: _______________________  163 PART 4: PROSTHETIC PRESCRIPTION PART 4 A: BODY-POWERED PROSTHETIC PRESCRIPTON Name: ___________________________________________________  Date: __________ Amputation Side:         Left                                Right                Bilateral Level of Amputation:   Wrist disarticulation      Trans-radial     Elbow disarticulation      Trans-humeral                Shoulder disarticulation  Prosthetic Components Recommendation: 1.  Socket/Suspension  Suction: ______________________________________________ Self suspension: ________________________________________ Harness: ______________________________________________ 2.   Cable System  Single Control               Dual Control 3.   Shoulder Unit  Friction     Locking    Other_________________________ 4.   Elbow Unit   Flexible Hinges      Rigid Single Axis       Rigid Polycentric  Step up             Other ____________________________ 5.   Wrist Unit   Constant Friction        Quick Disconnect       Flexion Unit  Other ______________________________________________ 6.   Terminal Device   Hook: (specify name) _________________________________   Voluntary opening  Voluntary closing Hand: (specify name) __________________________________              Voluntary opening  Voluntary closing  Passive type 6.   Remarks     164 PART 4: PROSTHETIC PRESCRIPTION PART 4 B: MYOELECTRIC PROSTHETIC PRESCRIPTON Name: ___________________________________________________  Date: __________ Amputation Side:         Left                               Right                Bilateral Level of Amputation:   Wrist disarticulation      Trans-radial     Elbow disarticulation      Trans-humeral               Shoulder disarticulation Prosthetic Components Recommendation: 1. Socket/Suspension Interface Suction: ______________________________________________ Self suspension: ________________________________________ 2.Myoelectric Control  Digital                Proportional 3. Shoulder Unit  Friction        Locking       Other_____________________ 4. Elbow Unit   Passive with electric lock  Passive with friction lock  Electric elbow                      Other ______________________ 5. Wrist Unit  Quick disconnect              Passive  Electric rotator                     Other ______________________ 6. Terminal Device   Hook ______________________________________________  Hand (Proportional control) ____________________________  Hand (Single speed) __________________________________  Bionic Hand ________________________________________  Other ______________________________________________ 7. Remarks      165 Test Fitting Protocol: Would the test fitting be available to the patient?  Yes  If yes, please fill in the following table.   No 1. Reasons for test fitting _________________________________________________ _________________________________________________ _________________________________________________ 2. Prosthetic components  _________________________________________________ _________________________________________________ _________________________________________________ _________________________________________________ _________________________________________________ _________________________________________________ _________________________________________________ 3. Training/ Fitting session _________________________________________________ _________________________________________________ _________________________________________________ _________________________________________________ 

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