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The effects of external ankle support on ankle joint talar tilt Bodnar, David Michael 1980

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c. i THE EFFECTS OF EXTERNAL ANKLE SUPPORT ON ANKLE JOINT TALAR TILT by David Michael Bodnar B.P.E., Univers ity of B r i t i s h Columbia, 1976 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF PHYSICAL EDUCATION in the School of Physical Education and Recreation We accept th i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA Ju l y , 1980 cT^  David Michael Bodnar, 1980 In presenting th i s thes is in pa r t i a l fu l f i lment of the requirements for an advanced degree at the Univers i ty of B r i t i s h Columbia, I agree that the L ibrary shal l make it f ree ly ava i lab le for reference and study. I further agree that permission for extensive copying of th i s thesis for scho lar ly purposes may be granted by the Head of my Department or by his representat ives. It is understood that copying or pub l i ca t ion of th is thesis for f inanc ia l gain sha l l not be allowed without my written permission. Department of l—Aw^.ic,f\L. •&&/)<-.ATIPIA ftub " ^ C K S A T I O U The Univers i ty of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date C\j-*-&.u,<rl- '& , I'l&.a i i ABSTRACT Injury prevention in a th l e t i c s has been the focus of much attent ion in recent years. Due to the frequency of i n ju r i e s a r i s ing about the ankle j o i n t , p r imar i l y involving the l a t e r a l c o l l a t e r a l ligament complex, many attempts have been made to re inforce the ankle j o i n t through the use of adhesive tape and preventative strapping. The purpose of preventative ankle strapping, as used in a t h l e t i c s , i s to reduce the frequency and sever i ty of ankle i n j u r i e s . Numerous methods of preventative strapping have been employed in a t h l e t i c c i r c l e s which attempt to r e s t r i c t or l i m i t the spec i f i c motion causing the in jury . The effectiveness of such devices in l im i t i n g only the motion which causes the in jury i s d i f f i c u l t to determine. The externa l l y applied c loth ankle wrap i s one such device which i s thoughtto increase ankle j o i n t s t a b i l i t y and thus l i m i t , to "some degree, plantar f l ex i on and invers ion. I t i s the combination of these two movements which are associated with the disrupt ion of the l a te ra l c o l l a t e r a l ligament, re su l t i ng in a l a t e r a l ankle sprain. The purpose of th i s invest igat ion was to study the ef fects of inversion forces applied to the ankle j o i n t s of cadavers and the resu l t ing inf luence on t a l a r t i l t . The subproblem of th i s invest -igation was to examine the af fects that an external c loth ankle support has on cadaver t a l a r t i l t when inversion forces were appl ied. i i i Seventeen unpreserved cadaver ankle j o i n t s were used as subjects fo r th i s study. The limbs for the study had no h i s tory of previous injury and had not been subjected to any s t ructura l damage pr ior to experimentation. The seventeen cadaver limbs were examined by x-ray analysis under two test condit ions, those being supported and unsupported. Each ankle j o i n t was subjected to four regulated loads under each condit ion. X-ray photographs were taken at the time each force was appl ied. The limb test ing took place with in 24 hours post-mortem. Attempts were made to test each ankle j o i n t to f a i l u r e under maximum loading conditions. The fol lowing hypotheses were tested for s ign i f i cance at the .05 l e v e l . 1. An increasing inversion force applied to the ankle j o i n t of a cadaver produced increasing t a l a r t i l t in a plantar f lexed foot pos i t ion . 2. The appl icat ion of an external c loth ankle support decreases the amount of t a l a r t i l t produced by inversion force in the plantar f lexed foot. Prel iminary analysis of variance revealed that there was a nons igni f icant difference regarding the order in which the ankle j o i n t s were tested. Mul t i var iate analysis of the data co l l ec ted revealed that hypothesis #1 was supported at the 0.001 level and that hypothesis #2 was supported at the 0.002 l e v e l . No s t a t i s t i c a l l y supported conclusions could be drawn from the data co l lected from the maximum load condit ions. iv ACKNOWLEDGEMENTS The invest igator would l i k e to express sincere appreciation to Dr. Robert Hindmarch, Mr. Bert H a l l i w e l l , Dr. Peter Grantham, and Dr. David Harder for the i r c r i t i c i sms and advice during the study. Had i t not been for the cooperation of Dr. English and Dr. Rutherford in the Department of Pathology at St. Paul ' s Hosp i ta l , the completion of th i s study would not have been possible. Thanks are also due to Dr. Ken Bentley-Corbett fo r his assistance with the rad io log ica l procedures and analys i s ; Mr. H. E i senhuthand Mr. K. Kucera, pathology ass istants for the i r time and cooperation; and f i n a l l y , to Dr. Bob Schutz and Mr. Marc Gessaroli for the i r assistance with the s t a t i s t i c a l analysis of th i s study. Many thanks. D.B. v V TABLE OF CONTENTS Page LIST OF TABLES LIST OF FIGURES Chapter 1 INTRODUCTION 1 Statement of the Problem 3 Subproblem . 3 J u s t i f i c a t i o n and Signif icance of the Study . . . 4 Hypotheses 5 Delimitations 5 Limitations and Assumptions 6 Def in i t ion of Terms 6 2 REVIEW OF LITERATURE 13 Mechanism of the Ankle Sprain 13 Talar T i l t 16 Related Cadaver Studies 18 Inversion Forces Applied to the Ankle Jo int . . . 2 0 External Ankle Support 21 Summary 23 3 METHODS AND PROCEDURES 25 Subjects 25 Time and Duration of the Study 26 Stress Platform Description 29 Pin Placement 31 Lower Limb Alignment 33 Appl icat ion of Ankle Jo int Support 34 Chapter vi Page Procedures for Stress Appl icat ion to the Ankle Jo int 38 Talar T i l t Measurement 40 Experimental Design . . . 41 S t a t i s t i c a l Treatment . 43 4 RESULTS AND DISCUSSION . . . . . 44 The Ef fect of Increasing Inversion Forces on Ankle Jo int Talar T i l t . 45 Hypothesis 53 Discussion 53 The Ef fect of an External Cloth Ankle Support on Talar T i l t of the Ankle Jo int 55 Hypothesis 69 Discussion 69 Results: The E f fect of Maximal Force Appl icat ion Upon Talar T i l t of an Unsupported Ankle Jo int 72 Discussion . . . 75 5 SUMMARY AND CONCLUSIONS 77 Conclusions 78 Recommendations for Further Study . . . 79 BIBLIOGRAPHY 80 APPENDICES 85 A -Torque Calculat ion 86 B - Individual Subject Data 89 vi i LIST OF TABLES Table Page 1 Experimental Design 42 2 Subject Data ". 44 3 Summary of Torques and Talar T i l t of Unsupported Ankle Joints 46 4 Observed Cel l Means . 52 5 Analysis of Variance for Grouping Af fect 52 6 Mean Talar T i l t Comparisons Between Subject Groups 1 and 2 for the Two Test Conditions . 56 7 Torques Producing Talar T i l t in Unsupported and Supported Cadaver Ankle Joints 57 8 Mult ivar iate Analysis Generating Univariate F and Probab i l i ty S t a t i s t i c s fo r the Variables Torque and Talar T i l t 59 9 Mult ivar iate Analysis Generating Step Down F S t a t i s t i c s and P robab i l i t i e s for the Variables Torque and Talar T i l t 60 10 Maximum Forces Producing Talar T i l t 73 11 Maximum Torques Producing Talar T i l t 74 vi i i LIST OF FIGURES Figure Page "I A Poster ior view of the ligaments of the ankle j o i n t 9 2.1 Ligaments associated with the l a te ra l aspect of the ankle 10 2.2 Ligaments of the ankle 11 3 The method used to measure the ta l a r t i l t angle in the ankle j o i n t 12 4 The portable x-ray unit that was used in this study ' 27 5 The stress platform 30 6 A cadaver limb f i rmly f ixed to the stress platform . 30 7 Placement of the pin through the plantar surface of the foot 31 8 Photograph of the actual pin placement . . 32 9 Limb alignment 34 10.1 -10.12 Sequential diagrams of the ankle wrap appl icat ion . 37 11 Stress appl icat ion to the ankle j o i n t 39 12 Relationship between stress and s t ra in for unsupported ankle jo in t s (subj. one to.eight) . . 48 13 Relationship between stress and s t ra in fo r unsupported ankle jo in t s (subjects nine to 17). . 48 M Relationship between stress and s t ra in for unsupported ankle jo int s (subjects one to 17) . . 49 15 D i s t r ibut ion and re lat ionship between the stress and s t ra in on unsupported ankle j o i n t s (subjects 1-8) 50 Figure 16 17 18.1 18.2 19.1 19.2 20.1 20.2 21.1 21.2 22.1 22.2 23.1 ix Page D i s t r ibut ion and re lat ionsh ip between the stress and s t ra i n on unsupported ankle jo in t s (subjects nine to 17) 50 Disbr i tubt ion and re lat ionship between the stress and s t ra in on unsupported ankle jo in t s (subjects one to 17) 51 Relationship between stress and s t ra in applied to unsupported ankle jo in t s (subjects one to ••; eight) 62 Relationship.;between stress and s t ra in applied to supported ankle jo in t s (subjects one to e i gh t ) . 62 Relationship between stress and s t ra in applied to unsupported ankle jo in t s (subjects nine to 17). 63 Relationship between stress and s t ra in applied to supported ankle jo in t s (subjects nine to 17). . 63 Relationship between stress and s t ra in applied to unsupported ankle j o i n t s (subjects one to 17) . 64 Relationship between stress and s t ra in applied to supported ankle jo in t s (subjects one to 17) . . 64 D i s t r ibut ion and re lat ionsh ip between stress and s t ra in applied to unsupported ankle jo in t s (subjects one to eight) . 66 D i s t r ibut ion and re lat ionship between stress and s t ra in applied to supported ankle jo in t s (subjects one to eight) . 66 D i s t r ibut ion and re lat ionsh ip between stress and s t ra in applied to unsupported ankle jo in t s (subjects nine to 17) 67 D i s t r ibut ion and re lat ionship between stress and s t ra in applied to supported ankle j o i n t s (subjects nine to 17) 67 D i s t r ibut ion and re lat ionsh ip between stress and s t ra in applied to unsupported ankle jo in t s (subjects one to 17) 68 X Figure Page 23.2 D i s t r ibut ion and re lat ionship between stress and s t ra in applied to supported ankle jo in t s (subjects one to 17) 68 1. CHAPTER I INTRODUCTION Injuries resu l t ing from competitive a th le t i c a c t i v i t i e s occur most frequently to the lower extremities (Pardon, 1977). Of a l l the lower extremity in jur ies contracted during a th le t i c pa r t i c i pa t i on , sprains and ruptured ligaments occur most frequently to the ankle j o i n t . The 1ateral,1igaments (external co l l a te ra l l igaments), which are composed of the anterior t a l o f i b u l a r , posterior t a l o f i b u l a r , and the calcaneofibular ligaments are most frequently involved in soft t i ssue dissorders of the ankle (Cox et a l . , 1977; Moseley, 1966; Rubin et a l . , 1960; Bonnin, 1950; Thorndike, 1948). The mobi l i ty of the foot i s ext raord inar i l y varied from person to person and seems to show no re la t ion to age, except that with increasing age, the foot tends to become less mobile. The wide var ia t ion in ankle j o i n t mobi l i ty displayed by the general population gives r i s e to the fact that ankle sprains are a very common occurrence in a th le t i c s . The sprain, one of the most common and d isabl ing in ju r ie s to be seen in a t h l e t i c s , is produced most frequently by a traumatic j o i n t twis t that resu l t s in the stretching or to ta l tearing of s t a b i l i z i n g connective t i ssues. Ankle sprains occur when the ligaments of the ankle are overstretched. In 1953, Ke l ly expressed the opinion that 2 common ankle sprains occur as a resu l t of an exaggeration of e i ther inversion (supination) or eversion (pronation) of the foot. When the ankle j o i n t i s forced beyond i t s normal anatomical l i m i t s , resu l t ing microscopic and gross pathologies can occur (Kennedy, 1976; Arnheim, 1973). The d i s t i nc t i on between a mild and a severe spra in, that i s , ligament stretching and par t i a l rupture as contrasted with a complete rupture of a ligament, has long been recognized. The c l i n i c a l term "sprain" i s commonly used to cover four separate e n t i t i e s , and i s therefore inexact, and requires considerable qua l i f i c a t i on before i t can be considered an accurate diagnosis (Bonnin, 1970). More s p e c i f i c a l l y , there i s injury to ligaments, to the a r t i c u l a r capsule and synovial membrane, and to the tendons crossing the j o i n t . Effusion of blood and synovial f l u i d into the j o i n t cavity usually accompanies th i s l e s i on , thus presenting a l l the c l a s s i c signs of inflammation ( jo in t swel l ing, loca l i zed temperature, point tenderness, and l a t e r , ecchymosis). According to the extent of the i n ju r y , sprains are commonly graded as f i r s t (mi ld), second (moderate), and th i rd (severe) degree sprains. The th i rd degree sprain frequently gives r i se to the chronic sprain condition (Arnheim, 1973). For the purpose of th i s study, f i r s t and second degree sprains w i l l be of prime consideration and importance. Attempts to reinforce ankle j o i n t s t a b i l i t y has been an area of prime importance for ind iv iduals interested in the f i e l d of a t h l e t i c injury prevention. Numerous methods have been employed attempting to support the ankle j o i n t (Arnheim, 1973; C a i l l e t , 1968; Lewin, 1959). 3 This has led to the development of many forms of external ly appl ied, synthet ic, supportive devices. The cost, effect iveness, and p r a c t i c a l i t y of many of these devices is often questionable. Data supporting the effectiveness of such devices i s l im i ted . One of the most common methods of external ly supporting the ankle j o i n t for a th l e t i c purposes i s through the use of the c loth ankle wrap (Arnheim, 1973; Lewin, 1959). A c loth ankle wrap i s thought to provide protection to the ankle j o i n t . The c loth ankle wrap i s reuseable and r e l a t i v e l y inexpensive when compared to other forms of support devices. The purpose of the wrap i s to give mild support against l a te ra l and medial motion in the ankle (Arnheim, 1973). The appl icat ion of various.forms of adhesive tape supports and e l a s t i c wraps are also frequently applied to provide support and increase ankle j o i n t s t a b i l i t y . STATEMENT' OF THE PROBLEM The purpose of the study was to invest igate the effects of inversion forces applied to the ankle jo in t s of cadavers and the resu l t ing influence on t a l a r t i l t (foot test pos it ion in that of plantar f l e x i on ) . SUBPROBLEM The subproblem of th i s study i s to examine the effects that an external c loth ankle support has on cadaver.talar t i l t when an inversion force i s appl ied. 4 JUSTIFICATION AND SIGNIFICANCE OF THE STUDY There i s a genuine concern regarding the prevention of a t h l e t i c in jur ies and as the majority of lower limb in ju r ie s sustained in a th le t i c s occur in and around the ankle j o i n t , i t appears appropriate to test the effectiveness of an ankle support on j o i n t s t a b i l i t y . Once the effectiveness of th i s type of external support i s analysed, comparisons may be drawn with other forms of support. A study of th i s nature w i l l form a basis on which to test other forms of ankle support, and to determine which type of support i s most e f fec t i ve in reducing the severity and frequency of ankle sprains. Radiographical analysis of the supported and unsupported ankles may provide useful information to the physic ian, a t h l e t i c therap i s t , and a th le t i c t ra iner with respect to the possible s t a b i l i z i n g e f fect of the c lo th ankle support.on the ankle j o i n t . Most ankle ligament i n ju r ie s occur under fast loading ( b a l l i s t i c ) conditions at.rates that have never been determined. However, these experimental resu l t s represent only the ef fects of a un id i rect iona l ten s i l e force and they are not d i r e c t l y appl icable to most c l i n i c a l i n j u r i e s , which resu l t from a combination of forces. Therefore, i t i s reasonable to assume that the re l a t i ve f a i l i n g point determined in these specimens i s relevant to the c l i n i c a l se t t ing . 5 HYPOTHESES 1. An increasing inversion force applied to the ankle j o i n t of a cadaver produces increasing t a l a r t i l t in a plantar f lexed foot pos i t i on . Rationale: The e l a s t i c properties of the ligaments providing strength and support to the ankle j o i n t w i l l allow the talus to t i l t wi th in the ankle mortise. When the ligaments have reached the i r l im i t s of e x t e n s i b i l i t y , further t a l a r t i l t w i l l re su l t in the disruption of those ligamentous f i be r s . 2. The appl icat ion of an external c loth ankle support decreases the amount of t a l a r t i l t produced by inversion force in the plantar f lexed foot. Rationale: A properly applied c loth ankle support should compliment the rest ra in ing properties of the ligaments surrounding the ankle j o i n t and thus decrease the a b i l i t y of the talus to invert within the ankle mortise. DELIMITATIONS 1. Inferences made from th i s study can be l im i ted only to male and female cadaver "subjects of varying ages (range between 24 and 77 years). 2. Subject test ing w i l l have taken place within 24 hours post-mortem. 3. Forces applied to the ankle j o i n t w i l l be mechanically applied within the laboratory. 6 LIMITATIONS AND ASSUMPTIONS 1. I t was assumed that the ankle jo in t s used for th i s study were i n t ac t , unpreserved, and had not been subjected to any structural damage pr ior to experimentation. No previous h i s t o r i c a l or autopsy evidence of disease or injury involving the ankle j o i n t had been i d e n t i f i e d . 2. Ankle j o i n t mobi l i ty varied from subject to subject, however s u f f i c i en t mobi l i ty existed to allow the appl icat ion of a c loth ankle support to each ankle j o i n t . 3. The accuracy of the resu l t s was l imited by the instruments used fo r measuring the forces applied to the ankle j o i n t and the varying degrees of t a l a r t i l t . 4. The flexed posit ion of the cadaveric feet could not be altered during the experimentation because of the r e s t r i c t i v e properties imposed on the ankle jo in t s by r i gor mortis. DEFINITION OF TERMS Inversion Inversion is ankle j o i n t movement in which the foot i s supinated. Eversi on Eversion i s ankle j o i n t movement in which the foot i s pronated. 7 In t r in s i c S t a b i l i t y I n t r i n s i c s t a b i l i t y i s considered to be the capacity of the ankle system to r e s i s t displacement in horizontal ro ta t ion , anter io -poster ior, and medio-lateral d i rect ions . These motions represent components of the more complex leg-foot movements of abduction-adduction and inversion-eversion. (Matejczyk, 1,979). . Junction Strength Junction strength is the load at separation of ligament from bone and dependant upon differences in age, sex, body weight, endocrine status, and physical a c t i v i t y level of the i nd i v idua l , (Tipton, 1975). External Support The purpose of external support i s to l i m i t movement of an injured or weakened part; to support; to increase s t a b i l i t y ; to exert compression; to reta in a part of the anatomy in the desired posit ion and correct minor deformities (Lewin, 1959). Sprain A j o i n t in which some or a l l of the f ibres of a supporting ligament may be stretched or ruptured i s considered to have sustained a sprain. The cont inuity of the ligament may remain i n t ac t , without d i s locat ion or fracture (.Dor-land's I l l u s t ra ted Medical Dict ionary). According to s t a t i s t i c a l evidence, the j o i n t s that are most vulnerable to sprains are the ankles, knees, and shoulders (Arnheim, 1973). 8 F i r s t Degree Sprain A f i r s t degree sprain is commonly c l a s s i f i e d as a mild sprain. I t i s characterized by a sudden t r an s i t o r y pain in the j o i n t . A f i r s t degree sprain produces mild d i s a b i l i t y with local weakness l a s t i ng up to a few minutes. Mild point tenderness with minimal hemorrhage, swel l ing, and causing st retch ing of ligamentous t issue i s also common (Arnheim, 1973). Second Degree Sprain This sprain i s commonly c l a s s i f i e d as a moderate sprain and i s characterized by sudden, prolonged pain that resu l t s in point tenderness, swel l ing, and l oca l i zed hemorrhage, and moderate d i s a b i l i t y . Weakness and painful movement o f ' t he part is t yp i ca l (Arnheim, 1973). Stretching and pa r t i a l rupturing of the ligaments may be indicated. Third Degree Sprain A th i rd degree sprain i s considered to be a severe sprain producing sudden, severe, and constant pa in, loss of funct ion, point tenderness, swel l ing, and hemorrhage. Extensive tearing and rupturing of ligamentous t issue i s usual ly indicated (Arnheim, 1973). Surgical repair of the damaged ligaments in a t h i r d degree sprain is . often required to re-estab l i sh j o i n t s t a b i l i t y . (Figure 1) Chronic Sprain A chronic sprain i s a long and continued condition having a gradual onset and tends to reoccur. C las s i c signs of i r r i t a t i o n and lack of j o i n t s t a b i l i t y are caused by repeated j o i n t stress. In l a t e r stages, traumatic a r t h r i t i s may be apparent with a pers i stent, low-grade inf lamation. 9 External Co l la tera l Ligament This group of ligaments i s most frequently involved in soft t i ssue dissorders of the ankle and consists of three d i s t i n c t bands, the anter ior t a l o f i bu l a r ligament, the poster ior t a l o f i b u l a r ligament, and the calcaneofibular ligament. (Figure 1) Medial Sprain Lateral Sprain Figure 1: A posterior view of the ligaments of the ankle j o i n t (includes i l l u s t r a t e d medial and l a te ra l 3rd. degree ankle sprains of the r ight ankle (Arnheim, 1973)). Ta lo f ibu la r Ligaments The anter ior t a l o f i bu l a r ligament passes forward and medially from the anter ior border of the l a te ra l ( f ibu la r ) malleolus to the neck of the ta lus . The posterior t a l o f i b u l a r ligament passes medially and backward from the l a te r a l ( f i bu la r ) malleolus to the poster ior process of the ta lus . (Figure 2.1 and 2.2, fol lowing) Figure 2.1: Ligaments associated with the l a te ra l aspect of the ankl'.e. A anter ior t a l o f i bu l a r ligament B calcaneofibular ligament 11 Figure 2.2: Ligaments of the ankle (Posterior-medial aspect). A deep delto id ligament B super f i c i a l de l to id ligament C transverse t i b i o f i b u l a r ligament D posterior t a l o f i bu l a r ligament 1:2 Calcaneofibular Ligament The calcaneofibular ligament passes from i t s attachment on the t i p of the l a te ra l malleolus downward and s l i g h t l y backward to the middle of the l a te ra l .surface of the calcaneus. (Figure 2.1) Ankle Joint The ankle j o i n t i s located between the talus and the mortise of the ankle j o i n t which is formed by the lower ends of the t i b i a and the f i bu l a (Figure 3) Talar T i l t Angle The t a l a r t i l t angle i s formed by the opposing a r t i c u l a r surfaces of the t i b i a and talus when these surfaces are separated l a t e r a l l y or medially by a supination or pronation force applied to the hind part of the foot (Rubin, 1960). (Figure 3) Fibula T ib ia Talus Figure 3: The method used to measure the t a l a r t i l t angle in the ankle j o i n t . 13 CHAPTER 2 REVIEW OF LITERATURE An extensive review of l i t e r a t u r e revealed an absence of data-supported information regarding the effects that any form of external ly applied ankle j o i n t support would have on t a l a r t i l t . For th i s reason, 1 iterature i nd i r e c t l y re la t ing to th i s study w i l l be examined. Mechanism of the Ankle Sprain The ankle j o i n t i s s ituated between the ta lu s , t i b i a , and f i bu l a and i s stable because of i t s mechanical configuration and surrounding ligamentous supports ( C a i l l i e t , 1968). The talus i s a bone with no muscular attachments and maintains i t s posit ion through the influence of the t i b i a , f i b u l a , and the calcaneus. The talus moves according to the design of the a r t i c u l a r surfaces within the l im i ta t i ons of the ankle ligaments. The talus transmits a l l of the stresses of body weight in normal pathways i f properly a r t i cu la ted . Normally, most of the stress reacts in the large posterior subtalar a r t i c u l a t i on . A wedge of bone, the sustentaculum t a l i , acts as a s t a b i l i z i n g post and provides the substrate to carry stress to the calcaneocuboid a r t i c u -l a t i o n . , The anterior facet of the calcaneus and calcaneonavicular 14 ligaments support the anterior surface of the ta lus. In the do r s i -flexed pos i t ion, the broader aspect of the talus i s forced between the mal leo l i and no l a te ra l motion is permitted. In the plantar f lexed pos i t i on , the narrow portion of the talus presents i t s e l f between the mal leol i and some l a te ra l motion i s possible. The neutral pos it ion and in pa r t i cu l a r , the plantar flexed posit ion of the foot , most frequently lend themselves to the p o s s i b i l i t y of a spra in. The most common mechanism by which an ankle sprain is produced i s by a forcefu l inversion of the plantar f lexed foot (Pardon, 1977; Arnheim, 1973; C a i l l i e t , 1968). It i s in th i s pos it ion that the ankle j o i n t i s most unstable. Inversion in ju r ie s are by f a r the most frequently occurring in jur ies to the ankle j o i n t (Inman, 1976). When an inversion in jury i s sustained, the foot is more l i k e l y to.be plantar f lexed than in a neutral posit ion or in do r s i f l ex i on . Ankle i n s t a b i l i t y i s best explained on the basis of indiv idual arrangement of the co l l a t e r a l ligaments. The changing roles of the components of the l a t e r a l . c o l l a t e r a l ligament in ankle s t a b i l i t y allows formulation of what appears to be a rat ional basis on which to explain various types of sprains. The l a te ra l c o l l a t e r a l ligament i s composed of the anter ior t a l o f i bu l a r ligament, the calcaneofibular ligament, and the posterior t a l o f i bu l a r ligament. A forcefu l inversion of the ankle while i t i s plantar flexed w i l l place the anter ior t a l o f i b u l a r ligament in a posit ion in which i t alone must withstand the imposed force. The calcaneofibular ligament, having been d i s -placed.into a more horizontal pos i t i on , Ms. less vulnerable. The reverse holds true i f the ankle is in f u l l do r s i f l ex ion (Inman, 1976). 15 Rarely i s the foot f o r c i b l y inverted while in a pos it ion of do r s i f l e x i on . Cox, 1977 stated that tear ing of the ligaments surrounding the ankle follows a progressive sequence. Typ i ca l l y , damage f i r s t occurs to the anter ior l a t e r a l capsule and the anter ior t a l o f i b u l a r ligament. Accompanying a complete anter ior t a l o f i bu l a r ligament d i s rupt ion, the calcaneofibular ligament is often stretched or to rn . In support of t h i s , a study conducted by Staples in 1975, on 27 athletes whose ankle jo in t s were su r g i ca l l y explored, demon-strated that a l l had sustained tears to the anter ior t a l o f i bu l a r ligament and 19 of those explored had addit ional i n ju r ie s to the calcaneof ibular ligament. (Figure 2.1) In plantar f l e x i o n , the anter ior t a l o f i b u l a r ligament plays the major ro le in r e s t r i c t i n g the medial t i l t i n g of the talus within the ankle mortise. The calcaneofibular ligament i s an important s t a b i -l i z e r of both the ankle j o i n t and the subtalar j o i n t . The posterior t a l o f i b u l a r ligament s t ab i l i z e s against poster ior displacement of the ta lus and therefore i s rare ly injured except in cases of complete ankle d i s l oca t ion (Bonnin, 1965). Avulsion of the bony tubercles usual ly occurs before the poster ior t a l o f i b u l a r ligament i s ruptured. Rubin et a l . , 1960, stated that when the plantar surface of the foot forms a ninety degree angle with the .shaft of the t i b i a and is in a plantargrade pos i t i on , the calcaneof ibular ligament is relaxed. In contrast , Rubin et a l . , confirmed that when the calcaneus i s f u l l y supinated, the calcaneofibular ligament can be f e l t to become taut beneath the palpating f inger. I f the foot i s plantar flexed and 16 then supinated, the calcaneofibular ligament can no longer be palpated as a taut band. Talar T i l t In the treatment of ankle sprains, i t i s important to know i f s u f f i c i en t damage to the l a te ra l c o l l a t e r a l ligaments has occurred to make the ankle unstable. In order to evaluate the status of the l a te ra l ligaments, i t i s necessary to establ i sh the normal amount of t a l a r t i l t of the talus which can be produced by supination of the heel in the normal foot (Rubin et a l . , 1960). Investigators (Freeman, 1965; Rubin e t a l . , 1960; Sed l in , 1960) have reported e i ther no t i l t of the talus in the normal ankle in response to stress in the d i rect ion of supination or a t i l t up to f i v e degrees. Occasionally, as much as ten degrees have been recorded and t a l a r t i l t i n g of varying amounts (up to 25 degrees) have been recorded in four to f i ve percent of ankle studies. These discrepancies are pa r t i cu l a r l y s i gn i f i can t since t i l t i n g of the talus i s used as a basic c r i t e r i on for surgical reconstruction of the injured l a te ra l ankle ligament. Concluding remarks made in a paper presented by Rubin et a l . , 1960 stated that "there was a wide var iat ion in t a l a r t i l t in normal ankles and that t a l a r t i l t of less than 23 degrees i s not a r e l i a b l e ind icator of a rupture of the l a te r a l c o l l a t e r a l ligament, even i f the two ankles of the same indiv idual tested are d i f f e r e n t . " A study conducted by Sed l in , 1960 stated that a t a l a r t i l t of over 20 degrees i s ind icat ive of l a te ra l ligament i n s u f f i -ciency (based on data acquired from 125 pat ients ) . Sed l in , 1960 17 found that a maximum t a l a r t i l t of 14 degrees was produced in unanesthetized normal ankles of patients with acute, contra latera l i n j u r i e s . Normal ankles tested under anesthesia showed maximum t a l a r t i l t i n g of only eight degrees. Maximum var iat ion between r i ght and l e f t ankles, in normal subjects was ten degrees. In anesthetized, injured ankles, t a l a r t i l t ranged from zero to 70 degrees. Ruptures were diagnosed by Freeman, 1964, i f the t a l a r t i l t on the injured side exceeded that on the uninjured side by s i x or more degrees. As a rough guide, 15 degrees has been accepted as the upper l i m i t of t a l a r t i l t in a normal ankle. The extent of damage found upon surgical invest igat ion was po s i t i ve l y associated with the degree of t a l a r t i l t (Sedl in, 1960). In an experimental production of ligament i n ju r ie s conducted by Watson-Jones, 1955, i t was found that complete tears occurred equally as often at the upper end, lower end, and middle of the ligament. These findings agree with those of c l i n i c a l pract ice. Avulsion of underlying bone occurs when the rupture i s at one end of the ligament. If the tear of the f ibres i s obl ique, i t i s possible for the ligament to remain in cont inuity with only minimal lengthening; no ret ract ion or gap i s produced and repair may take place with much less scar t issue than in the complete tear. Surgical repair in these cases i s rare ly j u s t i f i e d , but the lengthening of the ligament resu l t ing from the s t ra in may be occasional ly responsible for i n s t a b i l i t y , pa r t i cu l a r l y on a weight-bearing j o i n t such as the ankle j o i n t . 18 Analysis by Bonnin, 1965, of complications ar i s ing a f te r rupture of the calcaneofibular ligament, pointed out pers istent minor d i s a b i l i t i e s encountered by the ankle j o i n t in the f i r s t two years a f te r injury. . Of these d i s a b i l i t i e s , demonstratable t a l a r t i l t and i n s t a b i l i t y of the ankle occurs due to inadequate repair of the calcaneofibular ligament. Pers istent pain surrounding the ankle j o i n t , s t i f f ne s s , discomfort, and .often local tenderness over and below the anter ior t i b i o f i b u l a r ligament occurs and i s frequently c l a s s i f i e d as a 'chronic spra in ' of the.ankle. Vasomotor changes which produce persistent local edema and occasional venous d i l a t i o n about the j o i n t are common. Related Cadaver Studies Staples, 1975, stated that any comparative study of human jo in t s designed to determine the extent of indiv idual va r ia t ions * in ;the location .of axes of motion and to detect minor differences in movement i s beset with numerous d i f f i c u l t i e s . The use of external ly applied mechanical devices requires f i rm skeletal attachment of the devices. This i s d i f f i c u l t to obtain without pin or scew f i xa t i on d i r e c t l y to the a r t i cu l a t i ng bones. Direct inspection of the moving a r t i c u l a r surfaces i s impossible without surgical exposure. However, cadaveric i ne l a s t i c soft t issue e i ther r e s t r i c t s motion or imposes abnormal displacements on the moving j o i n t surfaces. Although cadaveric j o i n t surfaces g l ide with surpr is ing smoothness, they appear to react in accordance with the law of dry f r i c t i o n which bas i ca l l y states that 19 the greater the pressure between surfaces, the greater the force required to move them. The f i rm skeletal attachment and potential ligament destruction produced during test ing required the use of cadaver specimens as the source of test subjects upon which a projected s t a t i s t i c a l study could be based. Kennedy, 1976, conducted tension studies on cadaveric ligaments. No previous h istory or autopsy evidence of disease or injury involv ing the jo in t s was indicated. The ages of specimens used in Kennedy's study ranged from 20 to 75 years, with a mean of 62 years. He found that there was no s t a t i s t i c a l l y s i gn i f i can t corre lat ion between age and ligament f a i l i n g strength. L i terature re fer r ing to studies conducted by Kwong, 1979; Stauffer , 1979; D'Ambrosia, 1977, made no mention of any affects that the age of the subjects might have had on the outcome of t he i r studies and the influence of age on cadaver ankle j o i n t mobi l i ty . The cadaver experiments of Leonard, 1949, and Pennal, 1943, indicated that in the plantar f lexed pos i t i on , inversion stress places the anter ior t a l o f i b u l a r ligament under tension before the calcaneofibular ligament comes under tension, whereas with the foot at 90 degrees, the calcaneofibular ligament comes under tension f i r s t . No attention was paid,, in th i s study, to the posterior t a l o f i bu l a r ligament because l i t e r a t u r e revealed that i t i s ra re ly torn. 20 Inversion Forces Applied to the Ankle Jo int Wide var iat ions in amount of force applied to the ankle j o i n t may occur unless some control led quant itat ive method of applying the force i s employed. Nilsonne reported one case in which an ankle was tested in supination using a f i ve kilogram weight, but t h i s appears to be one of the few instances in which the force applied was measured. K le iger, 1957, used supports to hold the foot in invers ion, but the amount of force applied was not recorded. D'Ambrosia, 1977, studied the effects of ligamentous injury on ankle and subtalar jo in t s of ten fresh cadaver lower extremit ies. Results of th i s study based on sequential A-P and l a te ra l x-rays demonstrated the ef fects of horizontal rotat ion on the ankle. It was found that the t a l o t i b i a l and the talocalcaneal j o in t s part ic ipated s i g n i f i c an t l y in horizontal rotat ion in both normal and injured ankles. When the l a te ra l ligaments were e i ther completely or incompletely to rn , the t i b i o t a l a r j o i n t showed a tendancy to go into more adduction at 15 degrees to maximum plantar f l e x i on . The e f fect of horizontal rotat ion on the talocalcaneal and t i b i o t a l a r jo in t s due to in jury of the l a te ra l ligaments was shown to be less than 15 degrees dor s i f lex ion to maximum dor s i f l ex ion . D'Ambrosia, 1977, po s i t i ve l y supports the fact that l imi tat ions imposed by the anatomical composition of the ankle j o i n t i n h i b i t horizontal movement when the foot i s in a dors i f lexed pos i t ion. D'Ambrosia further..suggests that injury to the l a te ra l ligaments cause deviation of instant centers of rotat ion from the normal. This further suggests the important ro le played by in tact 21 l a te ra l ligaments on s t a b i l i z i n g the ankle j o i n t . No data in his.-study was presented that would provide information as to the amount of force applied to the cadaver ankle j o i n t s . External Ankle Support Ankle i n ju r i e s cons istent ly comprise a substantial portion of a l l i n ju r ie s in vigorous sports (Craig, 1973). This would explain the great attention focused upon attempts to reduce the i r incidence and sever ity. The American Medical Association in a publ icat ion introduced in 1973 stated two broad categories which af fect the jo in t s of the ankle: 1) the internal factors include the f i t of the bones within the j o i n t , the ligaments which hold the bones together, and the muscles that move or hold the j o i n t s in the appropriate pos i t ion ; 2) the prime external factors include wrapping or taping to support the j o i n t s , the strengthening of the structures surrounding the j o i n t s , and f i n a l l y the shoe-surface interface in a t h l e t i c s . In a study published by Tipton et a l . , 1975, i t was shown that the exercised ligaments of animals can be strengthened. These strengthened ligaments appear to be less t i g h t l y stretched between the i r bony attachments. Data from animal research cannot be necessar i ly extrapolated to humans. Ligament strengthening measures would appear to carry few r i sk s and have the p o s s i b i l i t y of minimizing injury potent ia l . The muscles surrounding the j o i n t can be strengthened. Rehab i l i -ta t i ve programs u t i l i z e this, mode of therapy and assume that th i s 22 contributes to the functional i n teg r i t y of the j o i n t and to the reduction of sprains. The American Medical Associat ion, in a pub l i c -ation edited by Craig in 1973, points out however that i t i s possible that due to the posit ioning of the muscles of the ankle, strengthening these groups of muscles would not appreciably a l t e r e f fec t i ve strength. The i n a b i l i t y to s i g n i f i c an t l y strengthen the internal structures of the ankle j o i n t led to the practice of wrapping and taping. Information brought forward in a publ icat ion edited by Craig in 1973 and compiled by the American Medical Association has led to the s tate-ment that wrapping and taping does increase ankle support. However, the support offered to the j o i n t by wrapping and taping i s substant-i a l l y reduced fol lowing exercise due to wrap or tape stretching. They also suggest that the mobi l i ty of the supported ankle i s not re s t r i c ted so that i t interferes with performance nor is support applied so f i rmly that stress received at the ankle j o i n t i s transferred to the knee. The emerging concepts of ankle protection indicate that a host of precautions must be considered to reduce the hazard of ankle injury. Many forms and methods of applying external support to the ankle j o i n t have been outl ined (Williams et a l . , 1976; Ferguson, 1973; Garrick et a l . , 1973; Cramer F i r s t Aider Manual, 1970; C a i l l i e t , 1963; Wil l iams, 1955) in recent l i t e r a t u r e . These a r t i c l e s have made mention of the most popularly accepted forms of ankle support. The materials used in providing support to the ankle j o i n t invar iab ly involve the appl icat ion of adhesive tape and/or c loth ankle wrap material of varying widths. These prescribed methods of providing support to the ankle j o i n t are commonly accepted, in one form or 23 another, by indiv iduals involved in a t h l e t i c therapy. Preferance as to the use of one type of support over another i s usually dictated by subjective evaluation involving references to the comfort, the ease of appl icat ion and removal of the support, and the ' f ee l i n g of support 1 emerging from the support appl icat ion. The most commonly employed methods of providing external support to the ankle j o i n t appear to be var iat ions of the so-cal led 'Basket-Weave' tape app l i c -at ion and the 'Louisiana Ankle Wrap', as outl ined by the " F i r s t Aider" t ra iners manual, published.by the Cramer Products, Inc., group. The appl icat ion of the c loth ankle wrap i s considered to be a preventative measure used to decrease the probab i l i ty of sustaining an ankle i n ju ry , in pa r t i cu l a r , a l a te ra l ankle sprain. A review of the ava i lable l i t e r a t u r e reveals that no. s t a t i s t i c a l l y supported data ex ists to show that one form of support i s superior to another or that methods used to support the ankle actual ly do increase s t a b i l i t y of normal or injured ankles. Summary A summary of avai lable l i t e r a t u r e reveals that a comprehensive study evaluating the effects that external ly applied ankle supports have on ankle j o i n t s t a b i l i t y has not been found. Anatomical l i m i t -ations imposed on the ankle make predictions possible as the mechanism by which ligament damage w i l l occur and the sequential order one could expect the ligaments to rupture. The function of the three main components of the l a te ra l co l l a te ra l ligament (the anter ior t a l o f i bu l a r 24 ligament, the posterior t a l o f i bu l a r ligament, and the calcaneofibular ligament) has been well documented. Cadaver specimens have been used extensively for research invo lv i the study of applied mechanical devices producing forces at various j o i n t s of the body which involve f i rm skeletal attachment of these devices. Some re s t r i c t i on s imposed by cadaver i ne l a s t i c soft t issue may make results derived from such studies inappl icable to the l i v i n g human. 25 CHAPTER 3 METHODS AND PROCEDURES Subjects 7 A tota l of 17 cadaver limbs ( i n t ac t , unpreserved ankle jo int s ) served as test specimens for th i s study. The ages of the specimens ranged from 24 to 77 years, with a mean age of 56 years. The cadaver specimens had no previous h i s t o r i c a l or autopsy evidence of disease or injury involving the ankle j o i n t s . The specimens used for th i s study were obtained from the Department of Pathology in Saint Paul ' s Hospita l . Testing took place in the laboratory with in 24 hours post-mortem. Six female and eleven male limbs were used. No comparisons were drawn between opposing ankle jo in t s in the same cadaver specimen. Cadaver specimen foot plantar f lex ion ranged from 35 degrees to 40 degrees. Any subject foot pos it ion beyond th i s range was omitted from th i s study. 26 Time and Duration of the Study The study took place between June 1979 and Apr i l 1980. Due to the a v a i l a b i l i t y of the subjects and the nature of the study, the experimentation was ca r r ied out on an indiv idual basis. A l l of the specimens were tested under two experimental condit ions, that i s , under non-support stress test ing and joint-support tes t ing . Evaluation and examination of t i l t i n g of the talus within the ankle mortise required instrumentation precise enough to detect movement measured in degrees. Radiological analysis of ankle j o i n t motion, while subjected to stress appl icat ion required the use of sophist icated apparatus and techniques. The fol lowing apparatus and instrumentation was u t i l i z e d for th i s study: (a) a portable General E l e c t r i c , manually contro l led x-ray un i t , Model number 11CK4-1, equipped with a pre-posit ioning f a c i l i t y and 10 inch by 12 inch X-omatic f i l m . This device was used for x-ray measurement of t a l a r t i l t of the ankle j o i n t in unsupported and supported conditions. (Figure 4) 27 Figure 4: The portable x-ray unit that was used in th i s study. 28 (b) a stress appl icat ion platform capable of applying inversion forces to the ankle j o i n t by means of an adjustable tu rn -buckle. (c) a Pac i f i c S c i e n t i f i c cable tensiometer, Model T5-6007-114-00 with one-sixteenth inch steel cable to monitor the force generated during the stress appl icat ion phase of the experiment. (d) a General E l e c t r i c x-ray viewer, Model 11FV 1 used for x-ray interpretat ion and evaluation. (e) a Kodak RP X-omat f i l m processor used to develop the 10 inch Nuclear Medicine NMB Kodak f i l m . (f) a 5/32 inch diameter s ta in less steel p in , nine inches in length. The pin was f i t t e d with a sta in less s t e e l , adjustable sleeve which could be adjusted to be af f ixed in any pos it ion along the pin by means of two set screws. The sta in less steel sleeve prevented the 1/16 inch steel cable attachment from moving along the p in . (g) ' a 3/8 inch var iable speed d r i l l which allowed forcefu l penetration of the sta in less steel pin into the plantar surface of the foot , the calcaneus, and f i n a l l y into the ta lus. (h) a 96 inch cloth ankle wrap, 1 1/2 inches in width produced in bulk by the Cramer Products, Inc., Kansas, U.S.A. 29 Stress Platform Description (Figure 5 and 6) The stress platform u t i l i z e d in th i s study was constructed in such a way that the lower limbs of the cadaver specimens could be anchored f i rmly to the platform. In doing so, the only movement allowable was from the ankle j o i n t (that i s , d i s t a l to the medial and l a te ra l ma l l eo l i ) . The dimensions of the platform were chosen a r b i t r a r i l y to provide a compact device capable of allowing the ankles to f i t properly over the x-ray cassette, and to make use of ava i lab le materials. The stress platform consisted of a 36 inch by 36 inch sheet of 3/4 inch plywood which was reinforced with 1 1/2 inch steel tubing on the undersurface. Two ve r t i ca l steel arms rose above the surface of the plywood, to which adjustable eyebolts could be fastened. The eyebolts provided a r i g i d anchor to attach the turn-buckle f o r stress app l icat ion. The eyebolt had a 3 inch vert ical :range of adjustment and was f ixed according to the elevation of the implanted pin into the plantar surface of the foot. This insured that the forces applied to the ankle jo in t s were pa ra l l e l to the surface of the platform. The plywood surface of the platform had one inch diameter holes randomly d r i l l e d through i t to allow fo r the insert ion of one inch diameter dowels. The dowels f i rmly f ixed the lower limbs of the cadavers to the stress platform. The dowels eliminated motion of the limbs during the period of stress app l i cat ion. 30 Figure 6: A cadaver limb f i rmly f ixed to the stress platform. 31 Pin Placement The point at which the pin penetrated the plantar surface of the foot was i den t i f i ed by means of locat ing super f i c i a l landmarks. By tracing a path towards the d i s t a l portion of the l a te ra l border of the foot , the tuberosity of the f i f t h metatarsal can be read i ly palpated. Using the tuberosity of the f i f t h metatarsal as a landmark, a pos it ion was located at one-half the distance to the posterior aspect of the calcaneus along the l a te ra l border of the foot. A point of penetration was then located on the plantar surface of the foot. The nine inch sta in less steel pin was then d r i l l e d through the plantar surface of the foot. The t i p of the pin penetrated the calcaneus, the subtalar j o i n t and terminated within the ta lus . (Figure 7) Figure 7: Placement of the pin through the plantar surface of the foot, penetrating the calcaneus and ta lus . 32 The pos it ioning and depth of penetration of the pin in the talus was checked by radio log ica l analys is. The depth of the pin penetration varied from subject to subject, depending upon the varying dimensions of the bone structures of the foot. By insert ing the pin into the calcaneus and ta lu s , subtalar t i l t was eliminated while t i l t i n g of the talus was unaffected. The adjustable steel sleeve secured to the p i n , marked the depth of pin penetration and the point of attachment of the steel cable. (Figure 8) Figure 8: Photograph of the actual pin placement. 33 Lower Limb Alignment Once the steel pin had penetrated the calcaneus and ta lus , the lower limb was secured to the test platform. The limbs were placed upon the test platform, with the non-tested limb elevated well above the surface of the platform, so as not to inter fere with tes t procedures performed on the contra lateral l imb. The test limb was aligned on the platform so that the shaft of the t i b i a and the pin protruding from the plantar surface of the foot were both perpendicular to the d i rec t ion of the forces to be exerted. The plantar surface of the foot, at pin level above the force platform, was pa ra l l e l to the l i ne of action of force app l icat ion. With the limb and foot properly a l igned, one inch diameter dowel pegs were inserted into the tes t platform along the medial and l a te ra l borders of the leg. With the pegs f i rmly implanted into the tes t platform, they were strapped together in a manner in which no s h i f t i n g of the pegs would occur during the course of the force appl icat ion period. This insured that movement of the shaft of the lower leg would be el iminated. (Figure 9) 34 4 « Figure 9: Limb alignment on the stress platform at the time of te s t i ng . Appl icat ion of Ankle Jo int Support Ankle j o i n t support was provided externa l ly in the fol lowing manner. Cloth ankle wrap mater ia l , 1 1/2 inches wide and 96 inches i n length, was applied to the ankle j o i n t over a t i gh t f i t t i n g a t h l e t i c sock (to simulate normal a th le t i c wrapping procedures). The ankle wrap appl icat ion commenced on the dorsal surface of the foot and was applied medial ly. (Figure 10.1) The f i r s t segment of the wrap 35 encompassed the foot, extending d i s t a l l y , no further than the middle of the longitudinal arch. Constant tension was maintained throughout the appl icat ion of the wrap and wrinkles in the wrap were el iminated. Having secured the wrap i n i t i a l l y (Figure 10.2), the c loth wrap then continued across the dorsal surface of the midtarsal j o i n t and across the medial malleolus (d i s ta l segment of the t i b i a ) . The wrap then continued around the posterior aspect of the ankle j o i n t and back toward the dorsal surface of the foot , thus covering the l a te ra l malleolus (Figure 10.3). Thus, the f i r s t ' f i gu re of e i gh t ' was completed. The c loth supportive wrap then continued into a series of 'heel l o c k s ' . A f ter the i n i t i a l .'figure of e i g h t ' , the wrap continued under the plantar surface of the longitudinal arch and obl iquely up and across the l a te ra l aspect of the ankle between the tuberosity of the calcaneus and the l a te ra l malleolus (Figure 10.4). The wrap then continued into a ' c o l l a r ' (Figure 10.5 and 10.6) around the d i s t a l segment of the l e g , overlapping and superior to the f i r s t ' f i gure of e i g h t ' . The second ' f i gu re of e ight ' fol lowed, crossing the dorsal surface of the foot in a l a te ra l d i rect ion (Figure 10.7), and extended up onto the dorsal foot surface (Figure 10.8 and 10.9). The second 'heel lock ' then commenced. The wrap continued across the l a te ra l malleolus, behind the foot and was applied obl iquely downward across the calcaneus (Figure 10.10), ju s t i n f e r i o r to the medial malleolus. If excess ankle wrap material was s t i l l to be appl ied, a series of ' f i gu re e ights ' terminated the appl icat ion of support. The c loth wrap was secured to the sock by the use of 1 1/2 inch adhesive tape which 36 was applied in a manner such that i t superimposed the 'heel locks ' and ' f igures of e i g h t 1 . (Figure 10.11 and 10.12) To el iminate any experimental 'orders a f f e c t ' , the order of test ing supported and unsupported jo in t s was a lternated. Figures 10.1 to 10.12: Sequential diagrams of the ankle wrap app l icat ion. 38 Procedures for Stress Appl icat ion to the Ankle Jo int The ankle j o i n t to be tested was f i rmly secured to the stress platform and the pin implanted into the plantar surface of the foot , passing through the calcaneus, subtalar j o i n t , and terminating in the ta lus . The amount of plantar f lex ion the foot exhibited at the time of test ing was recorded for each subject. The 1/16 inch steel cable was then secured to the pin by the adjustable metal sleeve, located on the plantar surface of the foot. The opposite end of the cable was l inked to the adjustable turn-buckle which in turn was secured to the eyebolt of the stress platform frame. A Pac i f i c S c i e n t i f i c cable tensiometer was then attached to the steel cable. The needle settings were a l l returned to zero pr io r to the commencement of experimentation. (Figure 11) A f i l m cassette containing ten inch by 12 inch Kodak RP X-omatic f i l m was placed under the plantar surface of the foot. The portable x-ray un i t was moved into posit ion and a sample x-ray was taken to ensure proper exposure and pos i t ion. The exposures were taken using a 100 centimeter focus f i lm distance. The exposure factors were kept constant at 70 Major KVP ( k i l o vo l t peak), 50 MA (Electrons per second), and a one second time exposure. The focal spot was 0.6 mi l l imeters . Figure 11: The method u t i l i z e d in th i s study to apply stress to the plantar f lexed cadaver ankle j o i n t s . 40 With the t i b i a f i rmly secured and aligned on the tes t tab le , sequential A-P x-rays were taken of the ankle j o i n t , c l ea r l y showing the talus within the ankle mortise. An x-ray was taken by the invest igator while zero, 11.4, 22.7 and 29.5 kilograms force was being applied to the-\ankle j o i n t . The resu l t ing change in the angular pos it ion of the pin protruding from the plantar surface with respect to the 1/16 inch steel cable was recorded at the time each x-ray was taken. The above sequence of events was repeated on each ankle under both supported and unsupported condit ions. The order of test ing supported and unsupported ankle jo in t s was a lternated, so an 'ordering e f f e c t ' of experimentation would not a r i se . When x-rays had been taken under both conditions with the applicaton of the four forces to each condit ion, the unsupported j o i n t was strained to a maximum force, re s t r i c ted only by the l im i ta t ions imposed by the equipment u t i l i z e d . Radiological analysis of the ankle j o i n t under th i s condit ion was also recorded by the invest igator. Talar T i l t Measurement Radiological analyses of the ankle j o i n t show that the lower (horizontal) a r t i c u l a r surface of the t i b i a on the anter ior -poster ior view appeared as two shallow domelike elevations on e i ther side joined at the midline by a s l i g h t depression. The subchondral bone of these domelike indentures was eas i l y seen as a f ine dense l i n e . This dense l i ne was overlapped by the less sharply defined, i n f e r i o r l y s ituated 41 anterior and poster ior a r t i c u l a r l i p s of the t i b i a l a r t i c u l a r surface. Occasionally, the subchondral bone formed a s t ra ight l i n e . The superior a r t i c u l a r surface of the talus showed two corresponding projections which conformed to the contours of the t i b i a l a r t i c u l a r surface. The l a te r a l elevation appeared at times to be s l i g h t l y higher than the medial, but th i s did not a f fect measurement since the t a l a r surface always corresponded. The t a l a r t i l t angle could therefore be measured with considerable accuracy from l ines drawn across the domes of the t i b i a and the corresponding eminances of the talus (Figure 3). These points of reference were c l ea r l y v i s i b l e even on oblique views of the ankle. The angle formed by these l ines was measured with a protractor and i den t i f i ed as the t a l a r t i l t angle. This method of obtaining the degree of t a l a r t i l t in the ankle j o i n t was s im i la r to that described by Rubin et a l . , 1960. The data co l lected by the invest igator was recorded and then rechecked and va r i f i ed by a resident rad io log i s t . Experimental Design This study used a 2x2x4 f ac to r i a l design with repeated measures on the l a s t two factors . The independant var iable i den t i f i ed in th i s analysis was torque (measured in kilogram-meters) and t a l a r t i l t angle (measured in degrees) was i den t i f i ed as the dependant var iab le. Any order af fect was accounted for in the experimental design. M u l t i -var iate analysis of variance was the s t a t i s t i c a l method used to analyse the raw data. Table 1 Experimental Design Groups Condition 1 Condition 2 Tl T2 T3 T4 Tl T2 T3 T4 Group 1 Subj. 1 8 Group 2 Subj. 9 17 43 S t a t i s t i c a l Treatment I n i t i a l s t a t i s t i c a l evaluation was performed on the experimental data to determine i f the order in which the subjects were tested (unsupported then supported and visa versa) had a s i gn i f i can t a f fect upon the pre and post tes t data obtained. The s t a t i s t i c a l program used to calculate the af fect of ordering on the data recorded was the UBC BMD:P2V (University of C a l i f o r n i a , Los Angeles, 1979 revised version) computer program. The UBC BMD:P2V program generated an analysis of variance with repeated measures. A 2x2x4 MANOVA with repeated measures on the l a s t two factors was used to tes t hypotheses 1 and 2. Each hypothesis was tested at an alpha level of .05. The MANOVA was calculated using the data col lected from the supported and unsupported ankle j o i n t s . The computer program ERSC:MULTIVAR, program version 6.2, was used to calculate the univariate and mult ivar iate analysis of variance. 44 CHAPTER 4 RESULTS AND DISCUSSION Seventeen cadaver ankle jo in t s were used in the study. Data was co l lected for each subject under the two test condit ions, unsupported and supported. Four t r i a l s fo r each of the two conditions were performed. Forces of 0, 11.4, 22.7, and 29.5 kilograms were applied to the ankle jo in t s under each test condit ion. The eight ankle jo in t s in group one were f i r s t tested in an unsupported condit ion, then in a supported condit ion. The nine ankle j o i n t s included in group two were f i r s t tested in the supported condit ion, then unsupported. Subject data i s summarized in Table 2. Table 2 Subject Data Group N Mean Age Standard Deviation 1 8 48.0 14.739 2 9 56.4 17.994 Total 17 56.35 17.506 45 The results of th i s study and the discussion of the resu lts are divided into sections which re late d i r e c t l y to the hypotheses stated in Chapter 1. The f i r s t section deals with the re lat ionsh ip between increasing inversion forces on the ankle j o i n t and the resu l t ing t a l a r t i l t in plantar flexed ankles of cadavers. The second section deals with the e f fect of the appl icat ion of an external c loth ankle support on ankle j o i n t t a l a r t i l t in cadavers produced when inversion forces were applied to the plantar f lexed foot. The th i rd section deals with attempts to produce ankle j o i n t f a i l u r e in cadaver ankles by increas-ing test inversion forces to maximum. The ef fect of increasing inversion forces on ankle j o i n t t a l a r t i l t . A summary of resu lts for a l l 17 subjects with unsupported ankle jo in t s i s presented in Table 3. This table of resu lts shows the effects of a r t i f i c i a l l y induced inversion forces (forces recorded in kilograms are translated into torques (kilogram-metres)) on t a l a r t i l t of a l l 17 subjects. Table 3 Summary of Torques and Talar T i l t  of Unsupported Ankle Joints Non-support Foot Condition 1 (Foot P lantar ' f l exed 35-40°) 0 ka m 11 .4 kqm 22.7 kqm 29.5 kqm cgm-m. T.T.° kqm-m. T.T.° kqm-m. T.T.° kqm-m. T.T.° Subj. 1 0 6.0 .970 6.0 1 .836 7.0 1.987 8.5 2 0 0.0 1.004 3.0 1 .904 5.0 2.275 8.0 3 0 5.5 .977 8.45 1.715 10.0 2.127 13.0 4 0 5.0 .955 10.0 1 .740 11 .0 2.066 11 .0 5 0 0.0 1 .090 2.0 2.056 5.75 2.415 9.0 6 0 3.5 .774 4.0 1 .337 6.25 1 .645 6.5 7 0 0.5 .702 5.5 1 .161 5.5 1.347 8.0 8 0 12.0 .853 13.5 1 .582 15.5 1 .924 18.0 9 0 5.5 .819 8.0 1 .231 8.5 1 .491 10.5 10 0 6.5 .726 7.85 1 .317 9.5 1.450 12.5 11 0 5.5 .949 9.0 1 .703 ;11.0 2.159 12.5 12 0 0.0 1 .038 2.25 1 .550 3.75 2.212 5.85 13 0 0.0 .870 3.0 1.476 5,25 1 .663 6.25 14 0 4.5 .825 7.0 1,-517 8.5 1.894 10.0 15 0 5.0 .762 8.5 1.326 9.0 1 .661 12.0 16 0 0.0 .913 3.5 1 .673 4.75 2.059 6.75 17 0 5.5 .837 9.5 1 .513 10.5 1.878 10.5 47 A more relevant and r e a l i s t i c measure of the force applied to the ankle j o i n t was made by converting the forces (recorded in kilograms on the cable tensiometer) into torques (kilogram-metres). By using the var iable torque as a measure of the force applied to the ankle j o i n t centre, not only was the measured force (kilograms) applied to the ankle j o i n t centre taken into account but also the distance from the j o i n t centre to the point of force appl icat ion and the angle at which the force was appl ied. The distance from the point of force appl icat ion to the ankle j o i n t centre (the midpoint between the superior surface of the talus and the i n f e r i o r surface of the t i b i a ) was calculated d i r e c t l y from the x-ray f i lms . The angle at which the force was applied to the ankle j o i n t was derived by means of external protractor readings. This angle was double checked by protractor readings taken d i r e c t l y from the x-ray f i lms . By knowing the force that was applied through the steel cable, the distance from the point of force appl icat ion to the ankle j o i n t centre, and the angle at which the force was applied to the ankle j o i n t , the resu l t ing torque applied about the ankle j o i n t centre could be ca lcu lated. An example of th i s ca lcu lat ion i s shown in Appendix A. Figure 12,13, and 14 i l l u s t r a t e the increasing re lat ionsh ip between the stress (calculated torques measured in kilogram-metre units) and the s t ra in (recorded as the change in t a l a r t i l t as measured in degrees) for unsupported ankle jo in t s of subjects one to e ight, subjects nine to 17, and subjects one to 17, respect ive ly. 0.5/ "j I I B Strain (degrees) 8 Figure 12: The re lat ionsh ip between the stress and s t ra i n for unsupported ankle jo in t s of subjects 1 to 8. Strain (degrees) Figure 13: The re lat ionsh ip between the stress and s t ra i n for unsupported ankle jo int s of subjects 9 to 17. 49 Stra in (degrees) Figure 14: The re lat ionsh ip between the stress and s t ra in for unsupported ankle jo in t s of subjects 1 to 17. The scatter plot Figures 15, 16, and 17 i l l u s t r a t e s the d i s t r i b u -t ion and re lat ionsh ip between the stress applied to the unsupported ankle jo in t s (calculated torques measured in kilogram-meter units) and the s t ra in (recorded as a change in t a l a r t i l t as measured in degrees) for subjects one to e ight, subjects nine to 17, and subjects one to 17, respect ively. 1 2.0 1 .5 Stress (kgm-m) 1.0 0.5/ Y 1 o Strain (degrees) : igure 15: The d i s t r i bu t i on and re lat ionsh ip between the stress and the s t ra in on unsupported ankle j o i n t s fo r subjects 1 to 8. 2.5. 2.0 1.5 Stress (kgm-m) 1.0 % X X X X X 0.5/' I 2 4~ fT Stra in (degrees) Figure 16: The d i s t r i bu t i on and re lat ionship between the stress and the s t ra in on unsupported ankle jo in t s for subjects 9 to 17. 51 2.5i 2.0 1.5 Stress (kgm-m) 1.01 0.5/ X 5 x X * * x * n r— 1 2 Stra in (degrees) Figure 17: The d i s t r i bu t i on and re lat ionsh ip between the stress and the s t ra in on unsupported ankle jo in t s for subjects 1 to 17. The indiv idual resu lts for a l l 17 subjects are presented graph-i c a l l y in Appendix B. The graphs for each subject show the increasing trends of t a l a r t i l t i n g as more torque i s applied to the ankle j o i n t . The observed means for t a l a r t i l t in the ankle jo in t s of a l l 17 subjects are presented in Table 4. 52 Table 4 Observed Cel l Means Group T r i a l 1 T r i a l 2 T r i a l 3 T r i a l 4 1 4.063 6.563 8.262 10.250 (n=8) 2 3.611 6.522 7.878 9.666 (n=9) 1 & 2 3.824 6.541 8.059 9.940 (n=17) Preliminary analysis of the two groups using the UBC BMD:P2V computer program generated the fol lowing results in Table 5. This analysis indicated that there i s a nonsignif icant difference between the two test groups (p = 0.5258). Table 5 Analysis of Variance for Grouping Affect Source Df Mean Square F P Condition 1 24.192 13.80 0.0023 Group 1 31.644 0.42 0.5258 T r i a l s 3 8.277 6.50 0.0010 T r i a l s x Groups 3 0.032 0.03 0.9945 . 53 Hypothesis An increasing inversion force applied to the ankle j o i n t of a cadaver produces increasing t a l a r t i l t in a plantar flexed foot pos i t ion. Discussion In studies conducted by Pardon, 1977; Arnheim, 1973; C a i l l i e t , 1968, the a b i l i t y of the talus to t i l t within the ankle mortise has been shown to increase as the foot becomes more plantar f lexed. It i s in th i s plantar flexed posit ion that the narrow portion of the talus presents i t s e l f between the mal leol i and some la te ra l motion i s made possible. The cadaver specimens u t i l i z e d in th i s study had a range of plantar f lex ion between 35 and 40 degrees. I t was within th i s range of plantar f lex ion that the majority of the subjects were c l a s s i f i e d . Those limbs which demonstrated a degree of plantar f l ex ion beyond th i s range were not considered for experimentation. Due to the re l a t i ve i n e l a s t i s i t y and immobile nature of the cadaver ankle jo in t s in the plantar f l ex ion -dor s i f l ex ion plane of motion, no adjustments to the plantargrade posit ion of the foot could be made during experimentation. Concern regarding the order in which the te s t - re tes t protocols were administered was i d en t i f i e d . This concern gave r i s e to the random assignment of test ing order which resulted in eight subjects (Group I) being tested f i r s t in an unsupported condition and then retested using the previously described method of external support. In contrast, the nine subjects in Group 2 were f i r s t tested in the supported condition 54 and retested in an unsupported condit ion. The order in which the subjects within each group were tested was shown to be s t a t i s t i c a l l y nonsignif icant. Table 5 i l l u s t r a t e s the nonsignif icant ef fects of the te s t - re tes t order (p = 0J5258). The results from Table 4 indicate that the observed c e l l means' of t a l a r t i l t between each t r i a l and for both groups consistently increased as more torque was applied to the ankle j o i n t . The probab i l i ty of such a difference in observed c e l l means i s i l l u s t r a t e d in Table 5. From th is tab le , the F value of 6.50 y ie lds a probab i l i ty equal to 0.001. 1 The results from the present study showed that t i l t i n g of the talus within the ankle mortise did increase at a s i gn i f i can t rate when increasing inversion forces were applied to the ankle j o i n t . The increments of force used in th i s study (0.0, 11.4, 22.7, and 29.5 kilograms) were s u f f i c i en t to produce a s i gn i f i can t change in t a l a r t i l t between each t r i a l . This a b i l i t y to produce t a l a r t i l t in the ankle j o i n t coincides with studies conducted by Freeman, 1965; Rubin et a l . , 1960; Sedlinr,. I960. The i ne l a s t i c nature of cadaver soft t issue about the ankle j o i n t did not reduce the effectiveness of a te s t - re tes t experimental protocol and did not completely r e s t r i c t the a b i l i t y of the talus to t i l t with in the ankle mortise. Any damage sustained by the soft t issue or l a t e r a l ligaments of the ankle during the f i r s t test series was not s u f f i c i en t to adversely influence the retest data on the same ankle. Internal soft t issue and ligament damage could be va r i f i ed by 55 surgical examination however, retest ing of the ankle j o i n t would no longer be possible. For th i s reason, surgical exploration of the ankle jo in t s was not considered. A follow:-up study should be under-taken which would involve surgical exploration of the tested ankle j o i n t s . This type of examination would show the nature and extent of the soft t issue and ligament damage fol lowing one test protocol which produced v i s i b l e t i l t i n g of the ta lus . The e f fect of an external c loth ankle support on t a l a r t i l t of the  ankle j o i n t . The fol lowing resu lts also per ta in , in part, to the f i r s t hypothesis. The results tabulated in the f i r s t portion of th i s chapter are used to draw a comparison with the data co l lected from the same 17 ankle jo in t s under the supported condit ion. A comparison of observed means for t a l a r t i l t in the ankle jo in t s of a l l 17 subjects i s presented in Table 6. This table i l l u s t r a t e s the differences in t a l a r t i l t (measured in degrees) between subject groups 1 and 2 under the two test conditions (unsupported and supported ankle j o i n t s ) . 56 Table 6 Mean Talar T i l t Comparisons Between  Subject Groups 1 and 2 for the  Two Test Conditions (Supported and Unsupported). Group Unsupported Supported Tl T2 T3 T4 Tl T2 T3 T4 1 4 .063 6.563 8.262 10.250 3 .425 6 .413 7.413 8 .850 (n=8) 2 3 .611 6.522 7.878 9.666 2 .644 5 .044 6.189 7 .956 (n=9) 1 & 2 3 .824 6.541 8.059 9.940 3 .012 5 .688 6.765 8 .376 (n=17) The results in Table 7 summarize the data co l lected on the ankle j o i n t s of 17 cadaver specimens. The results presented i l l u s t r a t e the torques applied to unsupported and supported ankle jo in t s and the resu l t ing t a l a r t i l t . •Table 7 TORQUES PRODUCING TALAR IN UNSUPPORTED AND SUPPORTED CADAVER ANKLE JOINT JOINT NON SUPPORT JOINT SUPPORT 0 kgm. 11.4 kgm. 22.7 kgm. 29.5 kgm. 0 kgm. 11.4 kgm. 22.7 kgm. 29.5 kgm. Torque T i l t Torque T i l t Torque T i l t Torque T i l t - Torque T i l t Torque T i l t Torque T i l t Torque T i l t Subject §1 0.0 6.0 .970 6.0 1.836 7.0 1.-987" 8.5 0.0 5.5 .998 6.5: 1.742 7.0 1.873 8.0 2., 0.0 '. 0.0 1.004. 3.0 1.904 5,0 2.27.5 8.0. p.o 1.75 1.004 6.25' 1.904 7.0 2.275 7.5 i 0.0 '5.45 .977 8.45 1.715 10.0 2.127 1-3.0 - 0.0 -• - 4.75 .909 7.0 1.677 10.75 2.072 11.25 4.' 0.0 5.0 .955 10.0 1.740 11.0 2.066 11.0 0.0 3.0 .924 9.0 1:699-' 10.0 2.066 10.5 5 0,0 0.0 "1.090 2.0 2.056 5.75 2.415 9.0 0.0 0.0 1V066 2.0 1.880 2.5 2.324 4.5 6 0.0 3.5 .774 4.0 1.337 6.25 1.645 6.5 0.0 1.75 .842 4.0 1.549 4.0 1.676 5.5 7 0.0 0.5 .702 5.5 1.161 5.5 1.347 8.0 0.0 0.0 .805 3.0 1.565 4.5 1.478 8.0 8 0.0 12.0 .853 13.5 1.582 15.5 1.924 18.0 0.0 10.5 .902 13.5 1.656 • 13.5 2.032 15.5 Subject 19 0.0 5.5 .819 8.0 1.231 8.5 1.491 10.5 0.0 3.0 .866 - .7,-5 1.532 7.5 1.773 10.0 10 0.0 6.5 ' .726 7.85 1.317 . 9.5 1.450 12.5 0.0 3.25. .789 .5.5 1.358 . 7.75 1.572 10.0 11 0.0 5.5 .949 9.0 1.703 11.0 2.159 12.5 0.0 4.0 .977 7.25 1.836 .7.75 2.267 10.0 12 0.0 0.0 1.038 .2.25 1.550 3.75 2.212 5.85 0.0 0.0 1.088 1.0 1.933 1.5 2.245 3.45 13 0.0 0.0 .870 3.0 1.476 5.25 1.663 6.25 0.0 0.0 1.026 2.5 1.697 3.0 1.701 5.25 14 0.0 4.5 .825 " 7.0 1.517 8.5 1.894 10.0 0.0 5.0 .839 5.5 1.571 7.5 1.923 9.50 15 0.0 5.0 .762 8.5 1.326 9.0 1.661 12.0 0.0 4.0 .897 6.75 1.583 7.75 1.661 _ 9.50 16 0.0 0.0 .913 3.5 1.673 4.75 2.059 6.75 0.0 0.0 .972 2.0 1.773 4.75 2.059 5.75 17 0.0 5.5 .837 9.5 1.513 10.5 .1.878 10.5 0.0 . .4.5 .887 7.25 1.577 8.0 1.908 8.0 58 The computer program ERSC:MULTIVAR provided mult ivar iate analysis of the torque and t a l a r t i l t data which generated univar iate and step down F s t a t i s t i c s and p robab i l i t i e s . The generated s t a t i s t i c a l analysis producing step down F s t a t i s t i c s permitted the examination of the t a l a r t i l t data with the af fects of the independant var iable torque being removed. Table 8 presents the univariate F s t a t i s t i c s and p robab i l i t i e s with the variables tested being averaged over the two groups. The mult ivar iate F s t a t i s t i c fo r a l l of the Groups by Conditions Interactions (F = 0.7511 and the probab i l i ty of th i s happening being less than 0.672) and the group main affects are a l l nonsignif icant ( a l l computed values show a probab i l i t y greater than .10). There is a nonsignif icant order of test ing a f f e c t . 59 Table 8 Mult ivar iate Analysis Generating Univariate F  and Probabi l i ty S t a t i s t i c s for the Variables  TorqUe and Talar T i l t . Variable Hypothesis Mean Square Uni. F P Conditions (Torque) 0.628 10.162 0 .0062 Conditions ( T i l t ) 347.859 26.497 0 .0002 Conditions x Force L in 0.569 4.431 0 .0526 Conditions x T i l t L in • 123.930 3.909 0 .0667 Conditions x Force Quad 0.229 8.307 0 .0114 Conditions x T i l t Quad 0.895 0.306 0 .5882 Force Linear 2841.846 791.524 0 .0001 T i l t Linear 23324.829 285.266 0 .0001 Force Quadratic 25.615 555.701 0 .0001 T i l t Quadratic 61.370 5.929 0 .0279 *Mul t i var ia te F s t a t i s t i c s for a l l Groups x Conditions Interaction (F = 0.7511 and probab i l i ty less than 0.672) and the Group Main Affect are a l l nonsignif icant ( a l l values greater than .10). 60 The step down F s t a t i s t i c s and p robab i l i t i e s are .presented tin Table 9. This summary of resu lts for t a l a r t i l t indicates that there was a s i gn i f i can t Condition Af fect (p = 0.0023) and a s i gn i f i can t Condition by Force ( l inear) Af fect (p = 0.0111). Table 9 Mult ivar iate Analysis Generating  Step Down F S t a t i s t i c s and P robab i l i t i e s  for the Variables Torque and Talar T i l t Variable Torque Talar T i l t Step Down F P Step Down F P Condition 10.1622 0 0062 13.8889 0. 0023 Condition x Force (Tin) 4.4313 0 0526 Condition x T i l t ( l i n ) 8.5557 0. 0111 Condition x Force (quad) 8.3073 0 .0114 Condition x T i l t (quad) 2.8845 0. 1116 Force ( l i n ) 791 .5241 0 .0001 T i l t ( l i n ) 3.4913 0. 0828 Force (quad) 555.7005 0 .0001 T i l t (quad) 1.1301 0 3058 *The F s t a t i s t i c for Mult ivar iate test of equal ity of mean vectors-293.6904 with a probab i l i ty of less than 0.0001. 61 Figures 18.1, 18.2, 19.1, 19.2, 20.1 and 20.2 represent l i ne graphs which compare support versus nonsupport conditions for subjects one to e ight, nine to 17, and one to 17, respect ively. These f igures show the re lat ionsh ip between the stress applied to the ankle j o i n t which was measured in torque (kilogram-metres) and the s t r a i n , as measured by a change in degrees ta l a r t i l t . 62 2.5 , Stress (kgm-m) Stra in (degrees) Figure 18.1: The re lat ionsh ip between stress and s t ra i n applied to the unsupported ankle jo in t s of subjects 1 to 8. 2.5 1 Strain (degrees) Figure 18.2: The re lat ionsh ip between stress and s t r a i n applied to the supported ankle jo in t s of subjects 1 to 8. 63 2.5 2.0 1 .5 Stress (kgm-m) 1.0 0.5 1 1 2 4" § Strain (degrees) Figure 19.1: The re lat ionsh ip between stress and s t ra in applied to the ankle jo in t s of subjects 9 to 17 (unsupported). 2.5 Stra in (degrees) Figure 19.2: The re lat ionship between stress and s t ra i n applied to the supported ankle jo int s of subjects 9 to 17. 64 Stress (kgm-m) 4 6 Stra in (degrees) Figure 20.1: The re lat ionsh ip between stress and s t ra i n applied to unsupported ankle jo in t s of subjects 1 to 17. 2.5 2.0 1.5 Stress (kgm-m) 1.0 0.5 / T 2 4 6 8 Stra in (degrees) Figure 20.2: The re lat ionsh ip between stress and s t r a i n applied to supported ankle jo in t s of subjects 1 to 17. The scatter plot diagrams, l i s t e d as Figures 21.1, 21.2, 22.1, 22.2, 23.1 and 23.2 i l l u s t r a t e the d i s t r i bu t i on and re lat ionsh ip between the stress (calculated torques in kilogram-metres), and the s t ra in (recorded as the change in t a l a r t i l t as measured in degrees These figures represent the stress versus s t ra in d i s t r ibut ions for subjects one to e ight, nine to 17, and one to 17 respect ively. 66 2.5 2.0 1.5 Stress (kgm-m) 1.0 0.5 "21 3 W Strain (degrees) Figure 21.1: The d i s t r i bu t i on and re lat ionsh ip between the stress and s t ra in applied to unsupported ankle j o i n t s of subjects 1 to 8. 2.5 2.0 1.5 Stress (kgm-m) 1.0 X * 0.5/ ^ 5 g Stra in (degrees) Figure 21.2: The d i s t r i bu t i on and re lat ionsh ip between the stress and s t ra in applied to supported ankle j o i n t s of subjects 1 to 8. 67 Stress (kgm-m) 2.5 2.0 1.5 1.0 0.5/ * X 2 4 6 Strain (degrees) Figure 22.1: The d i s t r i bu t i on and re lat ionsh ip between the stress and s t ra i n applied to unsupported ankle j o i n t s of subjects 9 to 17. 2.5 2.0 1 .5 Stress (kgm-m) 1.0 0.5/ 2 4 6~ Stra in (degrees) Figure 22.2: The d i s t r i bu t i on and re lat ionsh ip between the stress and s t ra in applied to supported ankle j o i n t s of subjects 9 to 17. 68 Stress (kgm-m) 2.5 2.0 1.5 1.0 0.5/ X x.x V X X " -g % g -Strain (degrees) Figure 23.1: The d i s t r i bu t i on and re lat ionsh ip between the stress and s t ra i n applied to unsupported ankle jo in t s of subjects 1 to 17. 2.5, 2.0 1.5 Stress (kgm-m) 1 .0 i % X X X * X x * * y. X XX * * X X * X 0.57 Stra in (degrees) Figure 23.2: The d i s t r i bu t i on and re lat ionsh ip between the stress and s t ra in applied to supported ankle j o i n t s of subjects 1 to 17. 69 Hypothesis The appl icat ion of an external c loth ankle support decreases the amount of t a l a r t i l t produced by inversion force in the plantar f lexed foot. This hypothesis was supported as a s i gn i f i can t difference was found to ex i s t between the two conditions at the .05 level of s i g n i f i -cance. Discussion The results showed that a substantial reduction in t a l a r t i l t occurred when an external c loth ankle support was applied to the ankle j o i n t s of the cadavers. The step down F s t a t i s t i c derived from the mult ivar iate analysis showed that the probab i l i ty of obtaining such a difference between the two test conditions would occur 0.0023 of the time (Table 9). The main s t a b i l i z i n g factors offered by th i s method of ankle support came from the two ' f igures of e i ght 1 and the medial and l a te ra l 'heel l o c k s ' . The configuration.; of the ankle j o i n t lends i t s e l f to the appl icat ion of the ' f igures of e i gh t ' . The ' f igures of e ight ' compress the connective tissues surrounding the ankle j o i n t and thus contribute to the restra in ing properties of the wrap for ankle invers ion. The medial and la te ra l 'heel locks ' aid in r e s t r i c t i n g the amount of t a l a r t i l t . At the time the ankle support i s appl ied, the foot i s in an everted pos i t ion. This pos i t ion is maintained throughout the duration of the support app l icat ion. The rest ra in ing forces imposed upon the ankle j o i n t through both the medial and l a te ra l 'heel locks ' 70 contribute to maintenance of the everted foot pos i t ion. I t i s the rest ra in ing properties imposed upon the ankle j o i n t by the medial and l a te ra l 'heel locks ' which must be overcome to e l i c i t inversion of the foot and subsequent t i l t i n g of the ta lus . I f the 'heel locks ' were to be applied in the opposite d i r e c t i on , inversion of the foot and subsequent t i l t i n g of the talus would have been enhanced. Due to the immobile nature of the cadaver ankle j o i n t s , i t was impossible to determine i f the c loth ankle wrap had any a f fect upon dors i f lex ion or plantar f l ex ion of the foot. The results from Table 9 show that the interact ion between the conditions and the changing t a l a r t i l t in the ankle jo in t s was l inear in nature. The step down F s t a t i s t i c of 8.5557 produced a probab i l i t y of less than 0.0111. This probab i l i ty of 0.0111 c l ea r l y shows that the l inear change in t a l a r t i l t under the supported condition i s s i g n i f i c an t l y d i f fe rent from the l i near rate of change of t a l a r t i l t under the unsupported condit ion. The s i gn i f i can t l i near change i n t a l a r t i l t suggests that the range of mechanically produced torques used in th i s experiment were not of s u f f i c i e n t magnitude to cause a complete l a te ra l c o l l a t e r a l ligament rupture. The indiv idual graphic records for each indiv idual subject are presented in Appendix B. The graphic records for each subject cons istently show the supported ankle j o i n t producing less t a l a r t i l t than i t s unsupported counterpart. The somewhat l inear increase in t a l a r t i l t i s also evident from the indiv idual records. Many precautions were taken by the invest igator to l i m i t the number of problems which could have arisen during experimentation. 71 For consistency, the experimental range of plantar f lex ion was l im i ted to 35 to 40 degrees. The locat ion of the pin placement was checked by x-ray photographs for each subject tested. The invest igator systematical ly repeated the experimental procedures for each subject. The appl icat ion of the c loth ankle wrap was applied in an ident ica l manner by the invest igator for each test subject. Problems were encountered that imposed l imi tat ions upon the experimental resu lts produced. Due to the nature of the test procedures, i t was necessary to u t i l i z e cadaver ankle j o i n t s . Idea l ly , l i v i n g subjects would have been more su itable subjects upon which to base a study of th i s nature. The affects that r igor mortise imposed upon the ankle j o i n t mobi l i ty of these subjects most cer ta in ly affected the f i n a l results of th i s experiment. As a re su l t of th i s l imi ted range of j o i n t motion, the co l lected data and subsequent results can only apply to cadaver specimens. However, because s i gn i f i cant ,; inversion restra in ing properties were i den t i f i ed in th i s study u t i l i z -ing an external ly applied c loth ankle wrap, the p o s s i b i l i t y of acquir-ing the same degree of success upon l i v i n g ankle j o i n t s i s quite possible. Another problem arose due to the lack of j o i n t mobi l i ty for plantar f l ex ion and do r s i f l ex ion . The appl icat ion of an external ankle support used to prevent an inversion sprain should be applied to a dor s i f lexed, f u l l y everted foot. During the course of th i s experiment, the invest igator found i t impossible to achieve th i s foot pos it ion for the cadaver experiments. For th i s reason, the ankle wrap was applied to a plantar f lexed foot. This factor also proved to be a l im i t a t i on 72 which was imposed upon the resu l t s . Results: The e f fect of maximal force appl icat ion upon t a l a r t i l t  of an unsupported ankle j o i n t . This test protocol took place immediately a f ter test ing had been completed for each of the four test t r i a l s upon the supported and unsupported ankle j o i n t s . Table 10 i l l u s t r a t e s the raw data obtained upon the 15 unsupported ankle jo in t s which were tested to maximum. The maximum forces obtained for the 15 subjects tested ranged from 34.83 kilograms to 68.18 kilograms. The t a l a r t i l t recorded at the point of maximum force exertion ranged from 6.3 degrees to 18.5 degrees t a l a r t i l t . Table 11 i l l u s t r a t e s s im i la r information as Table 10, with the forces redorded in kilograms transformed into torques (kilogram-metres). The maximum torques recorded ranged from 1.5632 kilogram-metres to 3.5705 kilogram-metres. Table 10 Maximum Forces Producing Talar T i l t Condition:Unsupported Ankle Jo int Group 1 Maximum Force Talar T i l t (kgm) (degree) Subject 1 2 3 39. 64 13.25 4 68. 18 15.5 5 50. 0 9.0 6 36. 36 7.0 7 37. 10 9.0 8 53. 73 18.5 Group 2 9 40 91 14.0 10 36 36 12.0 11 46 99 16.5 12 53 73 7.-0 13 34 .83 6:3 . 14 56 .99 10.5 15 37 .88 18.5 16 40 .91 10.0 17 48 .44 11.5 Table 11 Maximum Torques Producing Talar T i l t Condition:Unsupported Ankle Jo int Maximum Torque (kgm-m) Talar T i l t (degree) 2.4505 13.25 3.5705 15.5 2.8621 9.0 1.6918 7.0 1.5632 9.0 2.8742 18.5 2.0649 14.0 1.8979 12.0 2.7061 16.5 3.1330 7.0 1.8680 6.3 [ 3.1077 10.5 » 1.6862 18.5 i 2.2404 10.0 ' 2.2305 11.5 Group 1 Subject Group 2 75 Discussion Discovering the precise point at which ankle j o i n t f a i l u r e took place was d i f f i c u l t to determine. Two l imi tat ions ar i s ing during experimentation greatly affected the inves t i gator ' s a b i l i t y to deter-mine and predict ankle j o i n t f a i l u r e . When an increasing amount of torque was applied to the ankle j o i n t through the pin attachment, the pin frequently became dislodged from i t s pos it ion with in the talus and calcaneus. Attempts to repos i t ion the pin and achieve a f i rm f i x a t i on with in the calcaneus and talus then became impossible. The second factor which l imited data co l l ec t i on f o r atta in ing the precise point at which j o i n t f a i l u r e occurred was imposed by the stress mechanism i t s e l f . Frequently, the maximum force was e l i c i t e d from the force table while the ankle appeared to remain r e l a t i v e l y i n tac t . In test t r i a l s where th i s s i tuat ion was encountered, no further increases in torque could be transmitted to the ankle j o i n t from the force table. The maximum torques produced by the force table were not of a magnitude s u f f i c i en t enough to further increase t i l t i n g of the ta lus . I t i s fo r these reasons that no s t a t i s t i c a l l y backed results could be obtained perta in -ing to the f a i l u r e of the ankle j o i n t fol lowing the appl icat ion of maximum inversion forces. Due to the lack of agreement among invest igators regarding the point at which j o i n t f a i l u r e i s though to occur, the extent of the ligament damage produced in th i s experiment i s d i f f i c u l t to pin point. Comparisons made between opposing ankle jo in t s were often d i f f i c u l t to a t ta i n . The maximum torques produced in th i s experiment caused no 76 gross ankle deformity or extreme degrees of t a l a r t i l t i n g (maximum tailar t i l t was measured at 18.5 degrees). The rough guide of 15 degrees which has been accepted as the upper l i m i t of t a l a r t i l t i n a normal human ankle (Freeman, 1964) indicated that a rupture of the l a te ra l c o l l a t e r a l ligament complex occurred only four times during th i s experiment. I t must be pointed out at th i s time that no s im i l a r guidelines appear to ex i s t for t a l a r t i l t produced in cadaver ankle j o i n t s . 77 CHAPTER 5 SUMMARY AND CONCLUSIONS Injuries resu l t ing from competitive a th le t i c a c t i v i t i e s occur most frequently to the lower extremities (Pardon, 1977). Of the lower extremity i n ju r i e s contracted during a t h l e t i c pa r t i c i pa t i on , sprains and ruptures ligaments occur most frequently to the ankle joint.. The l a te ra l c o l l a t e r a l ligaments which are composed of the anter ior t a l o f i b u l a r , poster ior t a l o f i b u l a r , and the calcaneofibular ligaments are most frequently involved in sof t t issue disorders in the ankle (Cox et a l . , 1977; Moseley, 1966; Rubin et a l . , 1960; Bonnin, 1950; Thorndike, 1948). The wide var iat ion in ankle j o i n t mobi l i ty displayed by the general population gives r i se to the fact that ankle sprains are a very common.occurrence in a t h l e t i c s . Attempts to reinforce ankle j o i n t s t a b i l i t y has been an area of prime importance for indiv iduals interested in the f i e l d of a t h l e t i c injury prevention. Numerous methods of applying support to the ankle j o i n t have been documented, however, data supporting the effectiveness of such devices i s l im i t ed . The purpose of th i s invest igat ion was to study the ef fects of an external ly applied cloth ankle support upon enhancing the s t a b i l i t y of the ankle j o i n t and reducing ankle j o i n t t a l a r t i l t . 78 Seventeen cadaver lower limbs were used as subjects for th i s invest igat ion. A l l subjects were obtained through the Department of Pathology at St. Paul ' s Hospital in Vancouver, B r i t i s h Columbia. The ankle jo in t s selected for th is study were i n t a c t , unpreserved, and had not been subjected to any st ructura l damage pr io r to experimental; t i o n . No previous h i s t o r i c a l or autopsy evidence of disease, i n ju ry , or deformity involving the ankle j o i n t had been i d e n t i f i e d . The re l a t i ve lack of cadaver ankle j o i n t mobi l i ty due to the onset of r igor mortise gave r i se to concern regarding the ef fects of the te s t - re tes t protocol required of the outl ined experimental procedure. Randomly assigned test ing order was employed to tes t th i s concern. The order in which the subjects were tested was shown to be s t a t i s t i c a l l y nonsignif icant as shown in Table 5. Cone!usions The fol lowing conclusions can be reached: 1. A s t a t i s t i c a l l y s i gn i f i can t increase in t a l a r t i l t occurred resu l t ing from the appl icat ion of increased torque to the ankle j o i n t . 2. A s i gn i f i c an t reduction in t a l a r t i l t was shown to occur when an external c loth ankle support was applied to the ankle jo in t s of cadavers. 3. The e f fect of maximum force appl icat ion upon t a l a r t i l t of an unsupported cadaver ankle j o i n t could not be po s i t i ve l y i d e n t i f i e d . 79 Recommendations for Further Study 1. Results from th i s study showed that a s i gn i f i c an t reduction i n t a l a r t i l t occurred as a resu l t of the appl icat ion of a c lo th ankle support. Identical tes t protocols should be performed test ing other popular forms of external ankle support. In th i s way, comparisons may be drawn as to the effectiveness of each support app l i cat ion. 2. The same type of study should be undertaken followed up by surgical exploration which would be helpful in confirming the extent of the ligament and soft t issue damage produced through experimentation. 3. The u t i l i z a t i o n of cinemagraphic x-rays would be useful in depicting a continuous record of the increasing t a l a r t i l t during the period of force app l icat ion. 4. A method of reproducing these test protocols upon l i v i n g jo in t s would el iminate the problems encountered in using cadaver limbs as test subjects. Results of such a study would have a more s i gn i f i c an t a f fect on the pract ica l use of external support methods f o r which they were designed. 5. Forces used to tes t such supportive measures should simulate the nature and magnitude of forces required to produce a t h l e t i c ankle j o i n t i n ju r ie s in the natural se t t ing . 6. S imi lar procedures studying the e f fect of support measures used in the prevention of i n ju r ie s to other human jo in t s should be examined and the i r effectiveness determined. 80 BIBLIOGRAPHY Arnheim, D.D., K la f s , C.E., Modern Pr inc ip les of A th l e t i c Tra in ing, 2nd ed., C.V. 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APPENDIX A TORQUE CALCULATION 86 APPENDIX A TORQUE CALCULATION Torque = F x 1 s in 6 Where F = the force recorded in kilograms by the cable tensiometer 1 = the distance from the point of force appl icat ion to the ankle j o i n t centre, s in 0 = the angle at which the force i s applied in re la t ion to the ankle j o i n t centre. 87 Subject # 1 Force Pin Depth Pin-wire Angle 1 11.2 kgm. .037 m. 52° Torque = F x 1 s in 9 = 11.2 x .037 x s in 52° . = .32655 kgm-m. therefore .32655 kgm-m. was applied to the ankle j o i n t centre producing X° t a l a r t i l t . APPENDIX B INDIVIDUAL SUBJECT DATA 

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