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An analysis of the effect of the rotational, convex, poly-axial, mechanical knee brace (prototype I).. 1977

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AN ANALYSIS OF THE EFFECT OF THE ROTATIONAL/ CONVEX/ POLY-AXIAL/ MECHANICAL KNEE BRACE (PROTOTYPE i) ON THE STABILITY AND DYNAMIC RANGE OF MOTION OF THE KNEE JOINT by CHRISTOPHER COOKE B . A . / B . P . H . E . , Queen's U n i v e r s i t y , 1973 B . E d . , Queen's U n i v e r s i t y , 1974 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE PJEQUIRENENTS FOR THE DEGREE OF MASTER OF PHYSICAL EDUCATION i n THE SCHOOL OF PHYSICAL EDUCATION AND RECREATION We accept t h i s t h e s i s as conforming t o the requ i red standard THE UNIVERSITY OF BRITISH COLUMBIA MARCH, 1977 (c^ Chr i s tcpher Cooke, 1977 In p resent ing t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the requirements fo r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e fo r reference and study. I f u r t h e r agree tha t permiss ion for e x t e n s i v e copying o f t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . It i s understood that copying or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l ga in s h a l l not be a l lowed without my w r i t t e n p e r m i s s i o n . Department of Graduate Studies, School of Physical Education and Recreation The U n i v e r s i t y of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 D a t e March 23, 1977 6 ABSTRACT The fu n c t i o n a l loss of knee s t a b i l i t v that r e s u l t s from s o f t t i s s u e and ligamentous i n j u r y i s a serious problem f o r the conpetitive athlete. Non-surgical attempts t o restore femoro-tibial s t a b i l i t y and function have been centered on the external a p p l i c a t i o n of supportive tape and a t h l e t i c knee braces. Several a t h l e t i c braces are a v a i l a b l e on the market today. The more s u b s t a n t i a l ones, however, have proven ajrtibersane and uncomfortable i n t h e i r attempts to provide support f o r the unstable knee. Prototype I of tlie r o t a t i o n a l , convex, p o l y - a x i a l , mechanical knee brace (Taylor Brace) was subjected to t e s t i n g t o deteririine i t s e f f e c t on knee s t a b i l i t y and dynamic range of motion. Electrogoniometric recordings of knee function i n three mutually perpendicular movement parameters were obtained from each subject at varying speeds of ambulation. Testing was conducted i n the laboratory f o r unbraced and braced conditions using a 2 x 2 c o l l a p s i b l e parallelogram chain electrogoniometer. Instant center of r o t a t i o n pathways and j o i n t surface v e l o c i t y angles were determined from roentgenogram analysis of the unstable knee f o r unbraced and braced conditions. Seven medial roentgenograms were taken of the knee with the femur f i x e d and the t i b i a moved from ninety degrees of f l e x i o n t o zero degrees of f l e x i o n i n increments of f i f t e e n t o twenty degrees. Stress analysis was c a r r i e d out on the unstable knee using a mechanical s t r e s s machine. Regulated forces were anplied t o the knee j o i n t and radiographic changes i n the range of medial and a n t e r i o r l a x i t y recorded f o r the unbraced and braced knee. Subjective evaluation was a l s o conducted i n which subjects evaluated the Taylor Brace v e r b a l l y , a f t e r each session of a c t i v i t y , and i n an o v e r a l l w r i t t e n assessement at the end of the study. Various aspects of brace construction and function were discussed under pre-determined c r i t e r i a . Electrogoniometric r e s u l t s showed that the Taylor Brace had a general r e s t r a i n i n g e f f e c t on unwanted i n t e r n a l - e x t e r n a l r o t a t i o n and varus-valgus movement of the knee. Reductions i n the flexion-extens range were a l s o recorded but were considered unimportant as a hindrance to t o t a l knee function. There was also an i n d i c a t i o n that the c o n t r a - l a t e r a l , unbraced knee pattern changed following bracing. There were no consistent trends i n the pattern or disoersion of the i n s t a n t center of r o t a t i o n pathways following bracing. A consistent s h i f t i n g p o s t e r i o r l y and s u p e r i o r l y of the i n d i v i d u a l centers and a change i n abnormal j o i n t surface v e l o c i t y angles, however, was noted following a p p l i c a t i o n of the T a y l o r Brace. Subjective evaluation suggested se v e r a l minor aspects of brace construction f o r improvement i n future prototypes. Triigh c u f f r i g i d i t y , t i b i a l abraison and brace slippage were c i t e d as areas f o r improvement. Knee j o i n t range and a r t i c u l a t i o n was considered excellent as well as ease of application, overal l brace comfort, lightness and cosmetics of design. ACKNOWLEDGEMENTS Had i t not been f o r the exoneration of Mr. George Taylor (G.F. Strong R e h a b i l i t a t i o n Center) t h i s study could not have taken place. His i n i t i a l kindness i n allowing the f i r s t prototypes o f h i s brace to be tested and h i s subsequent help and advice throughout have made t h i s study p o s s i b l e . Thanks are due to Dr. Robert Hindmarch, Ms. Sue F i f e , Dr. Ted Rhodes and Dr. David Harder f o r t h e i r c r i t i c i s m s and advice during tlie study. Thanks are also due to Dr. Frank Cox and Dr. T. Bridge (Workers' Compensation Board) f o r t h e i r advice on roentgenogtam technique; t o Ms. L e f k i Kriptos (G.F. Strong R e h a b i l i t a t i o n Center) f o r her help with roentgenogram analysis; to Mr. Steve Cousins (Canadian A r t n r i t i s and Rheumatism Society) f o r h i s kind help and advice during electrogoniometric t e s t i n g ; and t o the subjects, Bruce Goldsmid, Brian Barker and Doug F i n l a y f o r t h e i r time and cooperation. My thanks. F i n a l l y , a s p e c i a l note of thanks t o David Rankine and Bob F i e l d f o r t h e i r e x c e l l e n t a r t work, and of course t o L.C. v i TABLE OF CONTENTS Page LIST OF TABLES i x LIST OF FIGURES x Chapter I STATEMENT OF THE PROBLEM 1 Introduction 1 Nature and Scone of the Problem 2 Knee Brace Description 5 Statement of the Problem 9 J u s t i f i c a t i o n and Significance of tlie Study 10 Delimitations 10 Assumptions and Limitations 11 Def i n i t i o n of Terms 11 II REVTE.'/ OF THE LITERATURE 15 Electrogoniometric Studies 15 Recent Electrogoniometric Evaluation of J o i n t Motion 18 Electrogoniometry of Abnormal Knee Patterns 18 Functional Evaluation of Below-Knee Braces 19 Bracing the Unstable Knee 21 Instant Center of Rotation Theory . . . . 22 Summary 25 I I I METHODS AND PROCEDURES . . 27 Subjects 27 v i i Chapter Page Apparatus and Instrumentation 27 Experimental Procedure 29 Subjective Evaluation 29 Test C r i t e r i a 30 Electrogoniometric Measurement 31 Instant Center of Rotation Measurement 37 Instant Center of Rotation Calculation 38 Stress Analysis 41 Anterior Laxity 42 Medial Laxity 43 Laxity Measurement Technique 45 IV RESULTS AND DISCUSSION 48 Electrogoniometer 48 Discussion 76 Instant Center of Rotation 79 Discussion 85 Stress Analysis 87 Discussion 89 Subjective Evaluation 90 Discussion 92 V SUMMARY AND CONCLUSIONS 94 Summar/ 94 Conclusions 97 VI RECENT DEVELOPMENTS AND SUGGESTIONS FOR FURTHER RESEARCH 98 New Prototypes 98 Suggestions for Further Research . . . . 103 BIBLIOGRAPHY - 104 v i i i Chapter Page APPENDICES 107 APPENDIX A - Knee Axes of Rotation . . . . 108 APPENDIX 8 - Subject Case Histories . . . . 110 APPENDIX C - 2 x 2 Collapsible Parallelogram Chain Electrogonicmeter 113 APPENDIX D - Electrogoniometric Testing Data Sheet 115 APPENDIX E - Instant Center of Rotation Calculation 119 i x L IST OF TABLES Table Page 1 Average values of knee motion during slow, l e v e l walking f o r Subject A with normal (stable) knees 49 2 Average values of knee motion during slow, l e v e l running for Subject A with normal (stable) knees 49 3 Average values of knee motion during slow, l e v e l walking for Subject B with abnormal (unstable) knee 56 4 Average values of knee motion during slow, l e v e l running f o r Subject B with abnormal (unstable) knee 56 5 Average values of knee motion during slow, l e v e l walking f o r Subject C with abnormal (unstable) knee 63 6 Average values of knee motion during slow, l e v e l running for Subject C with abnormal (unstable) knee 63 7 Average values of knee motion during slow, l e v e l walking for Subject D with abnormal (unstable) knee 70 8 Average values of knee motion during slew, l e v e l running for Subject D with abnormal (unstable) knee 70 9 Joint surface v e l o c i t y angles for Subject B, unstable knee, unbraced and braced 81 10 Joint: surface v e l o c i t y angles for Subject C, unstable knee, unbraced and braced 83 11 Medial l a x i t y values 87 12 Anterior l a x i t y values 88 13 Anterior l a x i t y reduction values 88 X L IST OF FIGURES Figure "age 1 Lennox-llill De-rotation Brace 3 2 Taylor Brace, l a t e r a l view 5 3 Taylor Brace j o i n t , exploded view . . . . 6 4 Posterior view of the knee with the Taylor Brace applied 7 5 Lateral roentgenogram of the knee with the Taylor Brace applied 8 5 Sequence view of knee with Taylor Brace applied 9 7 Comparison views of o f f s e t and i n - l i n e hinge j o i n t s 13 8 Instant center location with r e l a t i v e positions of the t i b i a and femur . . . . 24 9 Electrogoniometer anplication shaving the col l a p s i b l e parallelogram chain and potentiometer clu s t e r 31 10 Proper parallelogram chain position at 45 external rotation 32 11 Electrogoniometer application to the unbraced knee 33 12 Experimental set-up shaving segment of hallway used and equipment for electrogoniometer testing 35 13 Exoerimental apparatus for braced electrogoniometer testing 36 14 Subject positioning for instant center of rotation x-ray analysis 37 x i Figure Page 15 Centrode l o c a t i o n from the movement of two points 39 16 Instant center of r o t a t i o n t r a n s l a t i o n frcm 90 of f l e x i o n t o 10 of f l e x i o n . 41 17 Mechanical st r e s s apparatus positioned f o r a n t e r i o r l a x i t y measurement, j o i n t unstressed 42 18 Knee p o s i t i o n f o r medial l a x i t y measurement 44 19 Experimental set-ur) f o r medial l a x i t y measurement 45 20 Anterior l a x i t y measuring technique . . 46 21 Medial l a x i t y measuring technique . . . 47 22-A Electrogoniometric tracings of Subject A with normal knees during unbraced, slow, l e v e l walking 50 2 2 - B Electrogoniometric tracings of Subject A with normal knees durina slow, l e v e l walking with the Taylor Brace on the r i g h t knee 51 2 3 - A Electrogoniometric tracings of Subject A with normal knees during unbraced, slow, l e v e l running 52 2 3 - B Electrogoniometric t r a c i n g s of Subject A with normal knees during slow, l e v e l running with the Taylor Brace on the r i g h t knee 53 2 4 - A Electrogoniometric tracings of Subject 3 with abnormal knee during unbraced, slow, l e v e l walking 57 24-B Electrogoniometric tracings of Subject B with abnormal knee during slow, l e v e l walking with the Taylor Brace on the l e f t knee 58 x i i Figure Page 25-A Electrogoniometric tracings of Subject B with abnormal knee during unbraced, slow, l e v e l running 59 25- B Electrogoniometric tracings of Subject B with abnormal knee during slow, l e v e l running with the Taylor Brace on the l e f t knee 60 26- A Ele(_±rc>goniaTietric tracings of Subject C with abnormal knee during unbraced, slow, l e v e l walking 64 26- B Electrogonianetric tracings of Subject C with abnormal knee during slow, l e v e l walking with the Taylor Brace on the right knee 65 27- A Electrogoniometric tracings of Subject C with abnormal knee during unbraced, slow, l e v e l running 66 27- B Electrogoniometric tracings of Subject C with abnormal knee during slow, l e v e l running with the Taylor Brace on tlie r i g h t Isnee 67 28- A Electrogoniometric tracings of Subject D with abnormal knee during unbraced, slow, l e v e l walking 71 28- B Electrogoniometric tracings of Subject D with :abnormal knee during slow, l e v e l walking with the Lennox-Hill De-rotational 3race on the r i g h t knee 72 29- A Electrcgoniometric tracings of Subject D with abnormal knee during unbraced, slow, l e v e l running 73 29-B Elec±rwoniometric tracings of Subject D wita abnormal knee during Slav, l e v e l running with the Lennox-Hill De-rotational Brace on the right knee 74 x i i i Figure Page 30 Pathway of i n s t a n t center o f r o t a t i o n with respect to the t i b i a and femur f o r Subject B, l e f t knee, unstable . . . . 80 31 Pathway o f instant center o f r o t a t i o n with respect to the t i b i a and femur f o r Subject C, r i g h t knee, unstable . . . 82 32 Prototype I, Taylor Brace 93 33 Prototype I I , Taylor Brace 99 34 Prototype I I I , Taylor Brace 100 35 Prototype I I I , l a t e r a l view showina thigh and c a l f c u f f s with webbing removed . . . 101 36 J o i n t f i x a t i o n 102 37 Parallelogram chain linkages 113 38 Instant.center of r o t a t i o n c a l c u l a t i o n . . 119 CHAPTER I STATEMENT OF THE PROBLEM Introduction During normal a c t i v i t y , the ligaments o f the knee j o i n t are e s s e n t i a l f o r the c o n t r o l , i n t e g r i t y and s t a b i l i t y of the knee. The s p e c i f i c function of the i n d i v i d u a l ligaments (Wolf, 1973) and the f u n c t i o n a l loss that r e s u l t s from s o f t t i s s u e and ligamentous i n j u r / , s i n g l y or i n combination, has been w e l l documented (Kennedy, 1971;1973; O'Donoghue, 1973; Slocum, 1974; Hughston e t a l , 1976; and Eriksson, 1976). Internal derangement, as a r e s u l t of p a r t i a l o r complete lesions o f the ligamentous structures of the knee has been c l i n i c a l l y shown t o produce exaggerated medial and a n t e r i o r l a x i t y and i n s t a b i l i t y of the knee j o i n t with resultant pain and loss of f m o t i o n (Kennedy and Fowler, 1971). Attempts to restore femoro-tibial s t a b i l i t y by the a p p l i c a t i o n of external support have been approached from two d i r e c t i o n s . Researchers i n t e r e s t e d i n the non-surgical treatment of the athlet e 2 who wishes t o return to a t h l e t i c c c n p e t i t i o n , have studied the e f f e c t s of taping on the unstable knee (Roser, M i l l e r and Clawson, 1971; Noonan and Cooke, 1976). Bianechanical and medical researchers (Lehmann, Warren and DeLateur, 1970; Poser, M i l l e r and Clawson, 1971; Kennedy and Fabler, 1974) have been concerned with the e f f e c t of bracing on knee s t a b i l i t y , motion and a t h l e t i c function. Nature and Scope of the Problem Several a t h l e t i c knee braces are a v a i l a b l e on tlie market today, the Lennox-Hill Derotation Brace 1 being one that has been shown, with proper a p p l i c a t i o n , to reduce chronic knee i n s t a b i l i t y , pain and swelling i n damaged knees (Kennedy, 1974). Although supportive f o r the c o r r e c t i o n of medio-lateral and antero-posterior movement, tlie nature o f the a p p l i c a t i o n of the Lennox-Hill Brace, however, has tended t o s a c r i f i c e comfort, lightness and f l e x i b i l i t y f o r strength and support. Often obstructive on quadriceps and hamstring bulk, and i r r i t a t i n g through the p o p l i t e a l region of the knee with active use, tae Lennox-Hill Brace has proven curiaersome and uncomfortable. Information available on request from Hodgson Orthotics Ltd., 1650 West Broadway, Vancouver, B.C. V6J 1X6. The straps f o r the brace attachment to the thigh and c a l f , tlie b i - l a t e r a l derotation straps and the metal frame of the brace i t s e l f are c o n s t r i c t i v e and can reduce c i r c u l a t i o n to the underlying tissues (Figure 1). Figure 1. Lennox-Hill Derotation Brace shewing (A) and (C) straps f o r brace attachment to the thigh and c a l f ; (E) b i - l a t e r a l derotation straos and (D) metal brace frame. To the athlete, obstruction of muscle function and numbness o f tlie limb as a r e s u l t of c o n s t r i c t i o n o f surface vessels, and the i r r i t a t i o n on tlie s k i n can s e r i o u s l y hamper the duration of use and tlie e f f i c i e n c y o f walking or running. The movement mechanics of the Lennox-Hill, "Bub" DuribiLknit^ and PaLmerJ Athletic Braces have been built into bi-lateral supportive struts in the form of single hinge and off-set hinge joints (See Figure 1 , Definition of Terms). Allowing planar movement in the fixed, single-axis direction of flexion and extension, conventional athletic brace joint designs have ignored the internal-external rotation and varus-valgus movement of the tibia and femur that takes place during normal knee motion. Jesswein (1966) developed a polycentric knee joint that provided stability, at the same time allowing for a shifting of the knee brace axis with the angulation of the anatomical joint. Its one drawback for functional use was that i t only allowed flexion with weight-bearing up to fifteen degrees. To date, no mention has been found in the literature of a device flexible enough in its design to simulate the anatomical functioning of the human knee joint, that is not restricting because of its weight, that is ccmfortable and that can provide the necessary knee stability, support and dynamic function. 'Manufactured by John B. Flaherty Co., Incorporated, New York, N.Y. Distributed by Sparlings Sporting Goods, 929 Granville St., Vancouver, B. 'Developed by Rex 8 . Palirer, M.D. of Seattle. Available from Ouik-Cold Incorporated, Moberly, Missouri, U.S.A. 5 Knee Brace Description The rotational, convex, poly-axial, mechanical knee brace (Taylor Brace) prototype consists of a lateral leg iron composed of two independently articulating metal extensions held together at the knee by a common, convex base (Figure 2). The leg iron is constructed of .072 inch tempered, high carbon (C1095)' steel. Figure 2. Taylor Brace, lateral view. Articulation simulating an anatomical knee movement comes about by the geometric slotting on the joint ends of the extension arms 6 moving simultaneously on the convex surface of the base. The pathway o f the extension movement i s governed by pins s l i d i n g i n tne s l o t s . The nature of the convex surface of fahe base and the slope of the s l o t s on the extension arms, allows r o t a t i o n of the extensions to the i n s i d e and t o the outside (Figure 3). 7 The lateral leg iron i s secured to the leg by means of flexible, moulded thigh and calf cuffs. These cuffs are made of polyester resin, vacu-moulded from a positive cast of the leg. The moulded thigh and calf cuffs are lined with a foam padding to protect the skin i n the area of application. The articulating joint l i e s close to the skin at the knee but i s never in contact (Figure 4). Figure 4. Posterior view of the knee with the Taylor Brace applied. Note the position of the brace joint relative to the feiroro-tibial articulating surfaces. The arrow shows the location of the articulating joint close to the skin. Figure 5. L a t e r a l view of Taylor Brace applied. Note the l o c a t i o n of the brace j o i n t and the p o s i t i o n of the extension arms r e l a t i v e t o the shafts of the femur and t i b i a . A d d i t i o n a l medial support i s provided by an e l a s t i c strap webbing extending from the l a t e r a l l e g i r o n , over the p a t e l l a , across t i e medial aspect o f the knee and attaching t o the f i b e r g l a s s c u f f s . The p o p l i t e a l region of the knee i s , therefore, not r e s t r i c t e d (Figure 6). 9 Figure 6. Sequence view of Taylor Brace applied showing (a) lateral view, (b) anterior view witn medial support strap originating from lateral leg iron and crossing patella, (c) medial view and (d) posterior view shaving free popliteal region. Statement of the Problem The purpose of this study i s to determine the effect of the rotational, convex, poly-axial, mechanical knee brace (Taylor Brace) prototype on the s t a b i l i t y and dynamic range of motion of the human knee joint. 10 J u s t i f i c a t i o n and S i g n i f i c a n c e of the Study The study i s designed to apply the present work being done i n the f i e l d of o r t h o t i c bracing to a t h l e t i c s . In o a r t i c u l a r , i t i s being done to evaluate the Taylor Brace under f a i r l y n a t u r a l conditions of walking and running. I t i s also intended to u t i l i z e new developments i n the f i e l d o f electrogoniometry to analyse normal and p a t h o l o g i c a l knee function by determining p a t h o l o g i c a l patterns i n unstable knees and s p e c i f i c a l l y o f tne e f f e c t of bracing on knee function. The use o f a roentgenogram tedinique f o r the determination of the i n s t a n t center o f r o t a t i o n f o r the knee i s also being investigated and tne T a y l o r Brace i s being used t o evaluate the e f f e c t of bracing on that pattern. Stress analysis of j o i n t l a x i t y w i l l be included t o determine the e f f e c t of the brace on s t a b i l i t y of the knee under force a p p l i c a t i o n . Electrogoniometric and roentgenogram analysis of the function of t i e braced knee can provide information useful t o the orthopaedic surgeon, a t h l e t i c t r a i n e r and r e h a b i l i t a t i o n t h e r a p i s t on the e f f e c t of the Taylor Brace design on the function of the abnormal knee. Delimitations The determination of normal and p a t h o l o g i c a l knee function w i l l be confined to the evaluation of dynamic c l i n i c a l electrogoniometric data of the knee j o i n t . A l l functions of walking and running are performed i n the laboratory under c o n t r o l l e d conditions. Tne recorded data can, 11 therefore, only be i n t e r p r e t e d from t h i s r e s t r i c t e d s i t u a t i o n . The roentgenogram measurements f o r i n s t a n t center o f r o t a t i o n c a l c u l a t i o n were performed i n a l y i n g p o s i t i o n from ninety degrees of f l e x i o n to f u l l extension. Tlie non-weight-bearing nature o f the evaluation cannot, therefore, be c o r r e l a t e d with the function o f the knee j o i n t with weight-bearing. Roentgenogram stress analysis was c a r r i e d out i n the laboratory using mechanically simulated forces imposed at the knee j o i n t . Tlie r e s u l t s can only be considered from t i i s r e s t r i c t e d s i t u a t i o n . Assumptions and Limitations In the analysis o f electrogoniometric data, the following information i s taken i n t o consideration: (a) elgon accuracy as determined by j o i n t simulation reproduction w i l l keep the recording o f the data from knee function t o w i t h i n an e r r o r of four percent (Cousins, 1975:74). In determining the i n s t a n t center of r o t a t i o n f o r the knee, the following points w i l l be followed: (a) two f i x e d points on the femur are considered s u f f i c i e n t (Frankel and Burstein, 1971:916). (b) a l l medio-lateral and a x i a l r o t a t i o n movement o f the knee i s ignored and only f l e x i o n and extension w i l l be used. D e f i n i t i o n o f Terms D e f i n i t i o n of the following terms i s necessary f o r the understanding 12 of j o i n t function and movement parameters (See Appendix A: Knee Axes of Rotation). Flexion-extension Movement about the knee j o i n t i n tlie s a g g i t a l plane. Internal-external Rotation Inward and outward movement of tlie t i b i a about i t s long axis with respect t o the femur. Varus-valgus .Movement about the knee j o i n t occurring i n tlie coronal plane. Int e r n a l Derangement o f the Knee An anatomical disturbance o f the structures within the knee j o i n t , both bony and s o f t t i s s u e , r e s u l t i n g i n changes i n the mechanics o f the j o i n t . Medial Laxity The extent of the i n t r a - a r t i c u l a r gap o r distance between the most d i s t a l portions o f the sub-diondral bone o f the medial femoral condyle and the most d i s t a l l y placed portions of the sub-chondral bone o f the medial t i b i a l condyle. In damaged knees, medial l a x i t y increases with s t r e s s a p p l i c a t i o n as a r e s u l t o f ligamentous i n s t a b i l i t y . A n t e r i o r L a x i t y The amount of forward displacement o f the medial and l a t e r a l t i b i a l condyles with respect t o the medial and l a t e r a l femoral condyles. A n t e r i o r l a x i t y increases with s t r e s s a p p l i c a t i o n as a r e s u l t of ligamentous i n s t a b i l i t y . 13 Offset Hinge Jo i n t A j o i n t formed from, two extensions of metal caring together i n a corrmon hinge, allowing independent a r t i c u l a t i o n of the extensions i n a fixed, single-axis direction through ninety degrees. Tne hinge i s o f f s e t posteriorly from the l i n e formed by the metal extensions (Figure 7). Figure 7: (a) Offset hinge j o i n t and (b) hinge j o i n t . Iiinge Joint A j o i n t formed from two extensions of metal coming together i n a conTnon hinge allowing independent movemsnt of the extensions i n a fixed, single-axis d i r e c t i o n through ninety degrees. The hinge or point of a r t i c u l a t i o n i s i n l i n e with the metal extensions (Figure 7) . P o l y - c e n t r i c J o i n t A j o i n t formed through the geared a r t i c u l a t i o n of two extensions of metal about each other on a common plane. This allows movement i n a fixed-axis d i r e c t i o n . The geared nature o f the j o i n t produces a d r i v i n g a c t i o n with the r e s u l t that one metal extension i s driven about the other producing two axes o f r o t a t i o n . P o l y - a x i a l A term used t o define a r t i c u l a t i o n i n more than one plane o r about more than one axis. The human knee j o i n t i s p o l y - a x i a l i n that the axis of r o t a t i o n i s constantly s h i f t i n g or t r a v e l l i n g during active knee function. 15 CHAPTER II REVIEW OF THE LITERATURE Electrogoniometric Studies Electrogoniornetry* measures motion using potentiometer transducers. There are recording techniques for measuring joint motion using closed- circuit video tape, strobasccpic cinematography and motion analysis, but the techniques themselves are time consuming and the data must be reduced to useable numerical or graphical information. The electrogoniometer is externally worn by the subject and converts joint movement into voltage. The data produced is easily interpreted in direct graphical form. Electrogoniometric evaluation of human joint motion has been divided into the research activities of the following three major groups: (1) The investigations of Karpovich et al (1960, 1962, 1964, 1965) initiated the clinical use of the elgon. This device consisted of a potentiometer and two metal bars or lever arms, one attached to the potentiometer casing and one attached to the potentiometer shaft. * "electro" refers to the voltage produced by the potentiometer motion transducer; "goniometry" oomes from the Greek, gonia, which means angle and refers to angle movement. The device used is called an electrogoniometer, often referred to as an "elgon". 16 One lever arm was strapped above the joint and one below. By aligning the shaft of the potentiometer to the joint axis of rotation, joint motion in that plane could be measured. .Angular joint rotation was converted to a voltage output by the potentiometer, which was then graphically recorded. Flexion-extension of the knee and ankle joints were measured for normal and pathological gaits during various, everyday and athletic activities. The work of Karpovich et al initiated research into dynamic movement evaluation by providing an instantaneous recording of joint motion. This work was limited, however, because: (a) knee joint motion evaluation was limited to flexion-extension, ignoring the additional movement parameters of internal-external rotation and varus-valgus that take place coincident with the normal flexion-extension phase of knee articulation. (b) most of the published data was for one leg only; the movement of the unmonitored leg and its effect on gait pattern was not considered. (c) potentiometer alignment with the joint center of rotation was a matter of guesswork and could vary between successive applications to yield a significant source of error. The constantly shifting axis of the poly-axial anatomical knee joint could not be accurately accommodated by a fixed, single-axis mechanism. (2) Johnson and associates advanced the work of Karpovich, evaluating the movement of the hip (Johnson, 1969) and knee joints (Kettlekamp and Johnson, 1970) during normal walking and of the knee during activities of daily living (Laubenthal and Kettlekamp, 1972). Johnson and Kettlekamp established the first electxogoniometric values for the three mutually perpendicular rotations of flexion-extension, varus-valgus and internal-external rotation of the knee. Laubenthal and Kettlekamp provided useful electrogoniometric data of knee function during a c t i v i t i e s of climbing s t a i r s , l i f t i n g objects and s i t t i n g down. Although t h e i r work contributed t o the knowledge o f j o i n t motion, tlie s o l utions of Johnson and h i s associates were a l s o r e s t r i c t e d because: (a) t h e i r measuring device was not s e l f - a l i g n i n g and had to be posi t i o n e d f o r each t r i a l w i t h i n a given distance o f the cal c u l a t e d j o i n t center. (3) Lamoreux (1971), i n h i s studies of g a i t , s e t down the most extensive c r i t e r i a f o r the evaluation of human j o i n t motion. He developed and tested an exoskeleton device that simultaneously measured three dimensional motion of the p e l v i s and the major j o i n t s of tlie r i g h t lower extremity o f a s i n g l e , normal subject walking on a tr e a d m i l l . Measurements were made at s i x d i f f e r e n t speeds. Results were presented i n graphical form t o permit v i s u a l i n t e r p r e t a t i o n of the e f f e c t s of v a r i a t i o n s i n speed on the patterns of motion. Lamoreux's exoskeleton had s e l f - a l i g n i n g parallelogram linkages that made evaluation o f p o l y - a x i a l j o i n t s p o s s i b l e by the use o f sin g l e - a x i s potentiometers. Although enhancing r e p r o d u c i b i l i t y by reducing re-alignment e r r o r , Lamoreux's device had the following l i i r i i t a t i o n s : (a) the weight of the device (3.5 kilograms) made i t quite cumbersome and d i d not allow more mobile a c t i v i t y than normal walking. (b) the hip analog was not s e l f - a l i g n i n g , again introducing tlie e r r o r o f alignment f o r successive t r i a l s . (c) tlie complicated a p p l i c a t i o n o f two s e l f - a l i g n i n g parallelogram linkages f o r evaluation o f ankle motion produced a bulky device. (d) the elaborate nature of a p p l i c a t i o n l i m i t e d i t s use to a laboratory. 18 Recent Electrogoniometric Evaluation of J o i n t Motion Recent work by Cousins (1975) has produced a parallelogram chain design capable o f measuring, simultaneously, t r i - a x i a l movement o f the hip, knee and ankle j o i n t s . As each parallelogram s c i s s o r s "unwanted tr a n s l a t i o n s are absorbed while three mutually perpendicular rotations pass through the chain unchanged." This allows the device to be e s s e n t i a l l y s e l f - a l i g n i n g and evaluation o f f l e x i o n - e x t e n s i o n , i n t e r n a l - external r o t a t i o n and varus-valgus movement can be c a r r i e d out. The r o t a t i o n a l movement passing through the chain i s r e g i s t e r e d by potentiometers positioned along the axes of r o t a t i o n and a permanent graphical record i s obtained. The device has been developed f o r easy, b i - l a t e r a l a p p l i c a t i o n , i s l i g h t (1.7 kilograms) and n o n - r e s t r i c t i n g . I t can be used f o r indoor or outdoor t e s t i n g at varying rates of ambulation. C l i n i c a l a p p l i c a t i o n of the parallelogram chain device i s c u r r e n t l y teing investigated f o r the evaluation of normal and p a t h o l o g i c a l g a i t s . R e p r o d u c i b i l i t y o f the electrogoniometer was measured by p l a c i n g i t on a normal subject and obtaining a g r a p h i c a l record o f l e v e l walking. The equipment was then removed, replaced and tested again. This tecnnique was repeated a number o f times f o r various subjects u n t i l r e p r o d u c i b i l i t y was achieved. Electrogonicmetry of Abnormal Knee Patterns Kettlekamp e t a l (1970) presented data on abnormal knee patterns 19 from t h e i r studies o f knee motion i n normal g a i t . Elec±rogonioiretric tracings of a p a t i e n t with degenerative genu varum showed greater knee extension during the stance phase than during n e u t r a l stance. They a l s o produced data from a p a t i e n t with rheumatoid a r t h r i t i s with a loss of bone from the l a t e r a l t i b i a l plateau and increased valgus. Elertrogonicmetric patterns o f the knee showed very l i t t l e flexion-extension. The abduction-adduction patterns were grossly abnormal with the swing phase of the l e g during normal walking being quite reduced. Karpovich and Tipton (1965) i n t h e i r studies of knee and ankle movements i n pathologic g a i t s showed electrogonicmetric data from patients recovering from i n t e r n a l derangements o f the knee. They shaved recordings from a patient recovering from an " i n d u s t r i a l accident" which re s u l t e d i n impaired extension of the r i g h t knee. As a r e s u l t of t h i s i n j u r y , f l e x i o n during tlie support phase of walking was absent and the patient walked s t i f f - l e g g e d . The second s e t of data was from a patient recorded four days a f t e r a r i g h t medial menisectcmy. The p a t i e n t walked with a limp and f l e x i o n i n the r i g h t knee was l i m i t e d to fourteen degrees as compared t o s i x t y degrees i n the l e f t knee. The s p e c i f i c nature of the i n j u r i e s , unfortunately, was not a v a i l a b l e . Their study was l i m i t e d to two sets of t r a c i n g s . Functional Evaluation o f Below-Knee i3races Published data on the f u n c t i o n a l evaluation of braoed limbs i s not abundant i n the l i t e r a t u r e . For the most part, i t has been 20 confined to minor references in studies of joint motion. Electrogoniatietric evaluation of braced joint function began with the work of Karpovich and Tipton (1964). In their study of the clinical evaluation of the electrogoniometer, they included sane information on the effect of wearing a below-knee, lower, left leg brace on the joint movement of a cerebral palsied individual. They found that a marked reduction in flexion occurred in the left knee range but l i t t l e change occurred in the right knee pattern. Their observations were limited to flexion-extension evaluation of an isolated individual. The other movement parameters of internal-external rotation and varus-valgus of the knee were not included and no data was available for joint function before bracing. Information on the type of brace used was not available. Rozin et al (1972) correlated electrogoniometric results of nip motion with electromyography of the muscles of the lower limb. A standard below-knee, drop-foot brace was used consisting of tovo side bars attached through a pivot joint to a heel stirrup. The drop-foot stop mechanism allowed ankle movement in the range of ten degrees of plantar flexion and free dorsi-flexion but eliminated the movements of abduction-adduction and inversion-eversion. The analysis was limited to normal subjects and the effect of bracing on pathological joint function was not considered. Electrogoniometric evaluation consisted of motion of the hip in the frontal and saggital planes and of knee flexion-extension during slow walking. Rozin et al found that continuous knee flexion occurred on the braoed leg as well as:persistent contraction of the quadriceps muscle. The mechanics of the brace used was below the knee and did not involve the knee joint. They suggested that these changes in the pattern of gait may explain early fatigue and the possible development of secondary degenerative changes of the knee joint. Biomechanical evaluation of knee function was carried out by Lehman et al (1970), who analyzed the forces affecting knee stability in normal subjects using short-leg, below-knee braces. Transducers were mounted just below the calf band or shell of the brace to monitor the force produced, in pounds, between the leg and the brace during the various phases of normal gait. Their study showed that many designs of belav-knee braces can be used to prevent hyperextension of the knee in conditions of genu recurvatum and that knee stability can be inhanced by the use of toe levers from the flat foot to the toe-off stage of stance. Bracing the Unstable Knee Roser et al (1971) have produced data concerning the effect of taping and bracing on medio-lateral and antero-posterior stability of the knee. Medial and lateral instability were measured in four male college athletes with clinically unstable knees by applying varus and valgus stress to the knee while maintaining i t flexed to twenty degrees. A twenty pound force was applied to the ankle via a felt sling keeping the knee stable. The knee was then flexed to ninety degrees and anterior and posterior stress exerted by applying a twenty pound force 22 on the proximal t i b i a . Roentgenogram evaluation was c a r r i e d out under these s t r e s s e d conditions and displacement of the a r t i c u l a t i n g surfaces c a l c u l a t e d f o r taped and untaped and braced and unbraced s i t u a t i o n s using one and one h a l f inch a t h l e t i c t r a i n e r ' s tape and a Palmer Knee Brace. The study shewed that the only s i g n i f i c a n t improvement i n s t a b i l i t y occurred i n antero-posterior movement with the combined use o f tape and a Palmer Knee Brace. Kennedy e t a l (1974) have made use of a c l i n i c a l s t r e s s machine t o apply forces t o the knee j o i n t . Medial, l a t e r a l and a n t e r i o r l a x i t y were measured by str e s s roentgenogram analysis and values obtained f o r patients with chronic knee i n s t a b i l i t y . The e f f e c t o f the ap p l i c a t i o n of the Lennox-Hill De-rotation Knee Brace on knee j o i n t l a x i t y was determined. Kennedy e t a l showed that nine out of 32 patients who had chronic i n s t a b i l i t y and who wore the Lennox-Hill Brace shaved marked reduction i n an t e r i o r displacement of the medial and l a t e r a l t i b i a l condyles. Case studies were c i t e d i n which displacement o f the t i b i a l condyles was reduced from ten millimeters to 0.5 millimeters medially and from 15.4 millimeters medially to one millimeter l a t e r a l l y a f t e r a p p l i c a t i o n o f the Lennox-Hill Brace i n two subjects. Instant Center of Rotation Theory Frcm Rouleaux's Theory of Machines (1876) we f i n d that " r e l a t i v e motions o f plane f i g u r e s i n a common plane (con-plane figures) may be considered to be a r o l l i n g motion and the motion of any points i n them 23 can be determined as soon as the centroids (or instantaneous centers of rotation) of the figures are known." This concept can be applied to a cylinder rolling on a plane or to two circles rolling on each other. If we consider the femur and tibia (a combination of cylinder and plane) to be rigid bodies undergoing angular motion in one, common plane (flexion-extension), then the points along that rigid body move, except one, that point being the instant center of rotation or centroid for the instant being considered. In considering the movement of the femur and tibia, we assume that a l l other axial rotations of internal-external rotation and varus-valgus do not exist. During articulation between these two links, movement nay be considered to be sliding or rolling. If the femur moves on a fixed tibia, sliding occurrs when the femoral axis remains at a constant angle with the axis of the tibia; or rolling occurs as the femoral axis undergoes angular motion relative to the axis of the tibia. Usual knee motion in the saggital plane is considered to be a combination of both. By locating the instant center, i t is possible to identify the type of motion at the articulating surface since an instant center on the surface indicates that there is a rolling motion, while an instant center not on the surface indicates that there is sliding (Frankel and Burstein, 1971). Figure 8-A shews a particular instant center with the relative position of the tibia and femur. The direction of the velocity of the instant center can be obtained by drawing a line perpendicular to a line joining the instant center to a point on the condylar surface. If tlie v e l o c i t y l i n e at the point o f contact between the j o i n t surfaces i s ta n g e n t i a l t o the surfaces, they w i l l be s l i d i n g on each other with a r e l a t i v e l y free and normal action as the knee moves (Figure 8-B). 8-A 8-B Figure 8. Instant center l o c a t i o n with r e l a t i v e p o s i t i o n s of the t i b i a and femur (8-A), and j o i n t v e l o c i t y l i n e t a n g e n t i a l t o the j o i n t surfaces (8-B). V e l o c i t y l i n e s non-tangential t o the j o i n t surface i n d i c a t e abnormal f r i c t i o n and wear at the poin t of contact as a r e s u l t o f some pa theme chanical change i n the a r t i c u l a t i n g surfaces. This means that the motion w i l l tend t o separate or compress the j o i n t surfaces, producing a cam-like action. S l i d i n g w i l l not be taking place but the f r i c t i o n a l and compressive forces a t the surface w i l l be increased. 25 The l e a s t amount o f f r i c t i o n occurs when the d i r e c t i o n of the j o i n t surface v e l o c i t y l i n e i s tangent t o the contact surface. Vtfien the l i n e j o i n i n g tlie i n s t a n t center to a p o i n t on the a r t i c u l a r surfaces a t t h e i r point o f contact i s perpendicular (ninety degrees) t o the a r t i c u l a r surfaces, then t h i s condition takes place. H e l f e t (1959, 1963) had r e l a t e d worn areas i n the tibio-femoral j o i n t to areas o f j o i n t surface i n contact with displaced menisci, f i b r o t i c f a t pads and to abnormal patterns as the r e s u l t of displaced o r damaged ligaments. The technique determines whether the surface d i r e c t i o n of the femoral and t i b i a l a r t i c u l a t i n g surfaces produces e f f i c i e n t s l i d i n g or not. Examination of the in s t a n t center o f r o t a t i o n pathway and the in s t a n t center j o i n t v e l o c i t y angles may i n d i c a t e abnormal patterns and abnormality of a r t i c u l a t i o n as a r e s u l t o f seme pathomechanical change i n the j o i n t . Summary A review of the a v a i l a b l e l i t e r a t u r e reveals that a comprehensive study evaluating the dynamic e f f i c i e n c y and function of an a t h l e t i c knee brace has not been found. I n i t i a l studies of braces involved the electrogeniometric evaluation of non-athletic, belaw-knee braces designed f o r the correction of foot deformity associated with c l i n i c a l conditions. Results from electromyographical and str e s s analysis studies shaved 26 r e s u l t s from normal subjects only. Evaluation o f a t h l e t i c knee braces has been confined t o the a p p l i c a t i o n o f external foroes f o r the c a l c u l a t i o n of j o i n t l a x i t y . Recent advances i n the electrogoniometric recording of j o i n t motion i n three a x i a l r o t a t i o n parameters appear s u f f i c i e n t to conduct an analysis o f knee motion o f the i n t e r n a l l y deranged knee and o f the e f f e c t of bracing on that pattern. 27 CHAPTER I I I METHODS AND PROCEDURES Subjects Three male athletes, ages twenty-four, twenty-five and twenty-nine years served as t e s t subjects f o r the study. One of the subjects (A) had normal (stable) knees with no previous h i s t o r y o f knee i n j u r y . Both o f the other subjects (B and C) had s u f f e r e d lesions o f tine medial c o l l a t e r a l ligament and the medial meniscus of one l e g as the r e s u l t of a t h l e t i c competition. In addition, one of the two subjects showed marked antero-posterior l a x i t y with i n t e r n a l t i b i a l r o t a t i o n under examination with the a n t e r i o r drawer t e s t . The abduction s t r e s s t e s t produced an abnormal amount of medial j o i n t l i n e opening. The second t e s t subject showed degenerative changes i n the a r t i c u l a r surface of the femur on roentgenogram examination. A diagnosis of osteochondritis dessecans was made. Both subjects r e l a t e d a h i s t o r y of chronic pain, s w e l l i n g and lack o f function of the i n j u r e d knee j o i n t with active use (See Case H i s t o r i e s , Appendix B). Apparatus and Instrumentation Dynamic evaluation of knee j o i n t motion requires instrumentation precise enough to detect and r e g i s t e r movement i n degrees. Roentgenogram analysis of i n s t a n t centers of r o t a t i o n of the knee j o i n t and s t r e s s 28 analysis require the use of sophisticated techniques and equipment. The following apparatus and instrumentation was available for this study: (a) two 2 x 2 collapsible parallelogram chain electrogoniometers* (Appendix C) capable of measuring movement in three planes. (b) a signal attenuator box to apply a voltage to the potentiometers and to reduce the signal from the electrogoniometer to a voltage recordable by the strip chart recorder. (c) an S.E. Laboratories ultra-violet strip chart recorder model 3006 for recording the knee joint movements in graphical form. Flexion-extension, internal-external rotation and varus-valgus of both knees were simultaneously recorded using six separate channels. A deflection of one millimeter on the graphical print-out was calibrated to register five degrees of motion. (d) a Phillips Telestater remote control x-ray unit with x-omatic film and fluorscopic pre-positioning facility. This device was used for roentgenogram measurement of tlie knee joint in braced and unbraced conditions for instant center of rotation analysis. (e) a Picker model 6800 S x-ray unit with single phase f u l l wave rectification and Kodak x-omatic regular intensifying screens. This device was used for roentgenogram measurement during stress analysis. (f) a General Electric x-ray viewer model 11 FVl for use in x-ray interpretation and evaluation. (g) a stress; application apparatus for applying foroes to the knee joint consisting of a hand rachet and supporting stand. (h) a Pacific Scientific cable tensiometer model 401-1C-2 with one-sixteenth inch steel cable to monitor the force generated during stress application. permission for use of the 2 x 2 collapsible parallelogram chain electrogoniometers has been kindly given by Mr. Steven Cousins of the Canadian Arthritis and Rheumatism Society, Vancouver, British Columbia, Canada. (i) a nylon s l i n g f o r comfortable attachment of the s t e e l cable to the l e g f o r s t r e s s a n a l y s i s . (j) three prototypes o f the l a t e r a l i r o n , rotational, +convex, p o l y - a x i a l , mechanical knee brace (Taylor Brace). Experimental Procedure The T a y l o r Brace was evaluated under the following t e s t conditions: (a) subjective evaluation (b) electrogoniometric measurement (c) i n s t a n t center of r o t a t i o n measurement (d) s t r e s s analysis Subjective Evaluation (i) Brace a p p l i c a t i o n The Taylor Brace was comfortably applied by the subject i n the following manner: the foot was i n s e r t e d through the thigh and c a l f c u f f s and the brace positioned on the l e g . The proximal extension arm of the brace was positioned p a r a l l e l t o and approximating the femur and the d i s t a l extension arm o f the brace was p o s i t i o n e d p a r a l l e l + permission f o r use o f the l a t e r a l i r o n , r o t a t i o n a l , convex, p o l y - a x i a l , meclianical knee brace prototypes has been k i n d l y given by Mr. George Taylor, G.F. Strang R e h a b i l i t a t i o n Center, Department o f Orthotics, Vancouver, B r i t i s h Columbia, Canada. 30 to and approximating the t i b i a (See Figure 5, page 8) . The center of the mechanical j o i n t was located i n a p o s i t i o n s i x centimeters above the head o f the f i b u l a i n a p o s i t i o n at the center o f the p a t e l l a with the knee i n f u l l extension (See Figure 4, page 7). The medial support strap was applied from i t s attachment on the l a t e r a l l e g i r o n , over the p a t e l l a , and secured t o "D" hooks on the thigh and c a l f c u f f s . The e l a s t i c t i b i a l strap was then tightened and secured to the t i b i a l c u f f . The femoral c u f f was aligned by l i n i n g up a fastener on the medial aspect o f the thigh. The e l a s t i c thigh strap was then tightened and secured t o a "D" r i n g on the femoral c u f f . ( i i ) Test C r i t e r i a With the Taylor Brace applied, the subject engaged i n a selected p h y s i c a l a c t i v i t y of h i s own choosing. A f t e r completion o f the a c t i v i t y , the subject was asked t o v e r b a l l y evaluate the brace on the following points: (a) comfort and f i t i r r i t a t i o n p o i n t s , pinching, c o n s t r i c t i o n and numbness, brace movement on l e g , slippage. (b) j o i n t function ease of a r t i c u l a t i o n , range of a r t i c u l a t i o n , r e s t r i c t i o n s to movement. (c) weight, s i z e , ease of a p p l i c a t i o n and removal, cosmetics. At the completion o f the study, the subject was asked f o r a written assessement as an o v e r a l l evaluation of the T a / l o r Brace. filectrogcnicmetric I^asurement Electrogoniometer application (i) unbraced The proximal attachment of the electrogoniometer consisted of thigh cuff frame constructed of 0.40 centimeter steel wire. The frame was fixed to the thigh by means of a velcro strap which extended behind the leg and was fastened. Two brass brackets fastened the oroximal arm of the electroopruareter rigidly to the frame and allowed no movement (Figure 9). Figure 9. Electrogonicmeter application showing the collapsible parallelogram chain and potentiometer cluster (arrows). Note the thigh and calf wire frames with the velcro attachments. Attachment of the d i s t a l arm of the electrogoniometer to the c a l f was accomplished i n the same manner. A metal wire frame was applied t o the c a l f muscles and secured by a velcro strap at the front o f the l e g . The d i s t a l arm o f the electrogoniometer was allowed t o telescope f r e e l y i n s i d e a hollow brass tube which was r i g i d l y attached to the frame. The potentiometer c l u s t e r was p o s i t i o n e d a t a l e v e l beside the p a t e l l a with the knee i n f u l l extension. Proper alignment o f the c o l l a p s i b l e parallelogram chain o f the electrogoniometer from i t s f u l l extended p o s i t i o n was achieved by r o t a t i n g i t outward from the knee t o an angle of f o r t y - f i v e degrees (Figure 10). Figure 10. Proper parallelogram chain p o s i t i o n (arrows) a t 45 external r o t a t i o n . Note the waist pack, um b i l i c a l cord and potentiometer leads. Power f o r the potentiometers was supplied by a standard 110 v o l t , 60 cycle w a l l o u t l e t v i a independent leads to each electrogonioneter. Voltage output from the potentiometers t r a v e l l e d to the recorder v i a an u m b i l i c a l cord attached t o a waist pack. ( i i ) braced The T a y l o r Brace was applied t o the knee as previously described. The electrogoniometer was attached t o the brace by "U"-beam st r u t s of aluminum bo l t e d t o the brace extension arms. The proximal attachment of the elgon consisted of a hollow brass tube attached to a p l a s t i c "I"-beam and r i g i d l y f i x e d t o the aluminum s t r u t (Figure 11). Figure 11. Electrogoniometer a p p l i c a t i o n t o the braced knee. Arrow points t o r i g i d "U"-beam aluminum s t r u t . Note the p o s i t i o n of the potentiometer c l u s t e r r e l a t i v e to the brace j o i n t . 34 The d i s t a l attachment of the elgon was constructed in the same manner. The elgon arms were inserted inside the hollow brass tubes. The proximal arm of the elgon was rigidly fixed to the brass tube by adhesive tape, while the di s t a l arm was allowed to telescope freely inside the tube. Potentiometer and parallelogram chain alignment were the same as previously described for unbraced attachment. Test Procedure Following application of the electrogoniometer, the subject walked about the laboratory to become accustomed to the apparatus. He then stood i n his natural standing position (neutral stance) and the recording light beam channels of the st r i p chart recorder were adjusted to the zero position. It should be noted that the zero position represents the standing position of the subject. Records of knee joint motion were then recorded as motion from the neutral stance position. M l tests were conducted i n the laboratory setting i n a segment of hallway forty meters long (Figure 12). The subject was instructed to stand at one end of the hallway and the recorder beams were adjusted to zero again. Tne subject then walked u n t i l ten steps were recorded, exclusive of the f i r s t and last steps of the walk. He then repeated the walk. Recordings were obtained under test conditions of slow, level walking and slow, level running. After a ten minute rest, the subject was asked to apply the Taylor Brace. B Figure 12. Experimental set-uo shewing segment of hallway used, (a) signal attenuator box and (bj ultra-violet l i g h t s t r i p chart recorder. The subject i s i n neutral stance with the brace and electjxigeniometer applied. The elgon was then mounted and the procedure repeated. The pattern of knee motion as represented by the ultra-violet light s t r i p chart recordings was determined from the beam deflection. Six channels were used to record, simultaneously, movements of flexion-extension, internal-external rotation and varus-valgus for both knees under unbraced and braced test conditions. A beam deflection of one millimeter on the pront-out represented five degrees of motion. The chart speed was set at five millimeters per second. An electrogoniometric testing data sheet was kept on the s t a t i s t i c s of each test (See Appendix D) . Figure 13. Experimental set-up f o r braced t e s t i n g . 37 Instant Center o f Rotation Measurement Instant center o f r o t a t i o n measurement was made po s s i b l e by the use of the P h i l l i p s T e l e s t a t e r remote control x-ray u n i t . The subject assumed a p o s i t i o n l y i n g on the side with the s e l e c t e d l e g underneath. The thigh was f i x e d t o the x-ray table by means of a canvas c u f f attached to the table edge. Tension i n the c u f f was c o n t r o l l e d by a rachet tig h t e n i n g device mounted to the x-ray table by a s l i d i n g bracket (Figure 14). Figure 14. Subject p o s i t i o n f o r i n s t a n t center o f r o t a t i o n x-ray analysis, ^ote the canvas c u f f (s) and the s l i d i n g bracket (d) f o r c u f f a p p l i c a t i o n t o the table. Superimposition of the medial and l a t e r a l condyles of the femur was obtained by fluoroscopy. A sample x-ray was taken t o ensure proper exposure and p o s i t i o n . The exposures were taken using a one hundred centimeter focus f i l m distance. Tlie exposure f a c t o r s were kept constant at one hundred MA, one-tenth o f a second at eighty Kvp. Kodak G film was used with x-omatic screens. The focal spot was 0.6 millimeters. With the femur fixed to the x-ray table, the tibia was manually moved by the experimenters from ninety degrees of flexion to f u l l extension in incremsnts of fifteen to twenty degrees. At each interval, a medial roentgenogram was taken of the knee joint. Care was taken to maintain the femur in a constant position. The oosition of the medial and lateral femoral condyles was monitored at each exposure to ensure superimposition. A total of seven medial roentgenograms were taken of the unbraced knee. The patient was told to s i t up and relax. The Taylor Brace was then applied in the previously described manner, and tlie process of x-ray exposures repeated. Seven medial x-rays were obtained of the knee joint with the Taylor Brace applied. The roentgenograms were then examined and the instant center of rotation calculated for the series of braced and unbraced exposures. Instant Center of Rotation Calculation From the study of Kinematics, or the relative motion between rigid bodies called links, we can derive the following statements for the evaluation of a joint: (a) the bones may be considered to be rigid bodies and to constitute kinematic links (Frankel and Burstein, 1971). (b) as one of the links rotates about the other, at amy instant in time there is a point which has zero velocity and constitutes the instantaneous center of rotation, or centrode. The centrode i s located by i d e n t i f y i n g the displacements o f two points on a limb segment as the segment moves from one p o s i t i o n to anotner. The successive p o s i t i o n s o f each o f these points are i d e n t i f i e d as tne segment moves and l i n e s are drawn connecting them. These l i n e s represent the s e r i a l t r a n s l a t i o n o f each selected point. I f perpendicular b i s e c t o r s are drawn through the l i n e nrLdpoint f o r eacn p a i r o f displacements, the i n t e r s e c t i o n o f these b i s e c t o r s represents tlie centrode or instantaneous center o f r o t a t i o n f o r t i a t p a r t i c u l a r segmental t r a n s l a t i o n (Figure 15). In considering the knee, the guiding action of ligaments and muscles on motion i n the s a g g i t a l plane causes a t r a n s l a t i o n o f the instantaneous center f o r successive p o s i t i o n s of the l i n k s . A pathway can therefore be constructed along which tlie i n s t a n t center Figure 15. Centrode l o c a t i o n from the movement of two points A, t o A- and B, t o B 2. Note tiie centrode l o c a t i o n (C) from the perpendicular b i s e c t o r s . 40 moves as the jo int goes from flexion to extension (figure 16). From the method of Rouleaux (1876) and later expanded by Frankel, Burstein and Brooks (1971), the instant center of rotation or centrode may be determined (Appendix E ) . Figure 16. Instant center of rotation translation from (A) 90° of flexion to (F) 10 of flexion. Note the instant center of rotation pathway (F) for the six successive knee positions. The arrows indicate the joint surface velocity angles at the point of contact between the articulating surfaces. Stress Analysis Regulated forces were applied to the knee joint using a mechanical stress apparatus. Radiographic changes in the laxity of the knee joint were recorded for unbraced and braced conditions to give an indication of knee stability. Anterior and medial laxity measurements were made for each subject with abnormal (unstable) knees. Anterior L a x i t y The subject was asked to assume a s i t t i n g p o s i t i o n on the s t o o l f a c i n g the d i r e c t i o n of force. The thigh o f the s e l e c t e d l e g was secured firmly t o the s t o o l . The knee was flexed t o ninety degrees and the ankle secured to the base o f the s t o o l by a s t r a n . A medial exDosure of the r e s t i n g j o i n t was made. A nylon s l i n g was then applied to the nroximal t i b i a and connected t o a one-sixteenth inch s t e e l cable. The cable was connected to the hand-cranked winch. The cable tensiometer was aoolied to t i e cable (Figure 17). Figure 17. Mechanical stress apparatus p o s i t i o n e d f o r a n t e r i o r l a x i t y measurement, j o i n t unstressed. Note the flexed knee p o s i t i o n , the ankle secured to the base of the s t o o l , the cable tensiometer (T) and t i e hand-cranked winch (W). 43 The subject was instructed to relax the muscles of the leg and a gentle pull was exerted on the proximal tibia. The force was gradually increased until a twenty pound equivalent reading was obtained on the cable tension indicator. The hand-cranked winch was then locked and a medial exposure taken of the stressed knee joint. The force was reduced and the subject told to relax. The Taylor Brace was then applied to the knee joint and the knee stressed again to twenty pounds. A third medial exposure was taken and the tension released. The three medial exposures were taken using the Picker Model 6800 S x-ray unit. Radiation consisted of 400 MA for one-sixth of a second at eighty Kvp with a bucky screen cassette. Medial Laxity Tne subject was asked to assume a supine position on the x-ray table with the knees flexed to twenty degrees. This position was maintained by sponge wadding. The knees were padded and secured together by a webbed, nylon belt. The thigh of the selected leg was positioned in an aluminum thigh cuff and securely fastened to prevent movement (Figure 18) . An antero-posterior exposure was then made of the knee in this resting position. With the thigh of the selected leg gripped firmly in the aluminum cuff, a nylon sling was applied to the ankle of the leg and connected to a one-sixteentn inch steel cable. The cable was attached to the hand-cranked winch and the cable tensicmeber positioned on the cable. 44 Figure 18. Knee p o s i t i o n f o r rnadial l a x i t y ireasurement. Note the sponge padding between the knees and under tlie knees f o r support and prot e c t i o n . The aluminum thigh c u f f (/•/) i s securely fastened to prevent movement. A gradual valgus tension was then aoplied t o the ankle. The subject was reminded t o relax the muscles of the l e g . Tne tension was increased u n t i l a twenty pound equivalent reading was obtained on t i e cable tension i n d i c a t o r . The winch was then locked and an antero-posterior exposure of t i e stressed knee j o i n t was made (Figure 19). The tension was released and the subject t o l d to re l a x . The Taylor Brace was then applied to the knee j o i n t and the knee stressed aaain to twenty pounds. A t h i r d antero-oosterior exoosure was made and tlie tension released. Tiie three antero-posterior exposures were taken using the Pi c k e r Model 6800 S x-ray u n i t . Radiation consisted of one hundred MA f o r one-sixth of a second at seventy-eight Kvp. Kodak x-omatic regular i n t e n s i f y i n g screens were used. A l l x-rays were developed using an R.P. X-omatic processor with the "rapid processing" technique. A l l x-rays were taken using Kodak G f i l m . Figure 19. Experimental set-up f o r medial l a x i t y measurement. Laxity Measurement Technique A n t e r i o r Laxity Anterior l a x i t y was measured by p l a c i n g exposure A ( f o r the unbraced, unstressed knee) with a v e r t i c a l l i n e t a n g e n t i a l t o the p o s t e r i o r condylar surface of the femur and another v e r t i c a l l i n e t angential to the an t e r i o r surface of the t i b i a l plateau. The same procedure was c a r r i e d out f o r the unbraced, stressed knee (exposure B) and f o r the braced, stressed knee (exposure C). Tie distance FmTm was measured and the excursion o f the a n t e r i o r surface of the t i b i a 46 recorded i n r e l a t i o n t o the p o s t e r i o r condylar surface o f tlie femur f o r the three exposures (Figure 20). A l l measurements were made with Vernier c a l i p e r s and recorded t o wi t h i n the nearest 0.10 m i l l i m e t e r as an i n d i c a t i o n of a n t e r i o r l a x i t y . A B C Figure 20. A n t e r i o r l a x i t y measuring technique showing (A) exposure A, unbraced, unstressed; (B) exposure B, unbraced, stressed; and (C) exposure C, braced, stressed. The distance FmTm was taken as the amount of a n t e r i o r l a x i t y f o r the stressed knee. Medial L a x i t y Medial l a x i t y was measured by p l a c i n g exposure A f o r the unbraced, unstressed knee with a h o r i z o n t a l l i n e t a n g e n t i a l to the most d i s t a l 47 portions of the sub-chondral bone o f both femoral condyles. Another h o r i z o n t a l l i n e was then drawn tange n t i a l to the most d i s t a l l y placed portions of the sub-chondral bone of both t i b i a l condyles. The same procedure was c a r r i e d out f o r the unbraced, stressed knee (exposure B) and f o r the braced, stressed knee (exposure C). Tne distance FoTo o r i n t r a - a r t i c u l a r gap f o r the three exposures was recorded f o r the medial side of the j o i n t (Figure 21). This distance was taken as the amount of medial l a x i t y as measured with the Vernier c a l i p e r s to the nearest 0.10 irdllimeter. Figure 21. Medial l a x i t y measuring technique showing (A) unbraced, unstressed; (B) unbraced, stressed; and (C) braced and stressed knee. The distance FoTo was taken as the amount of medial l a x i t y f o r tiie s tressed knee. CHAPTER IV RESULTS AND DISCUSSION Electrogoniometer Data was c o l l e c t e d f o r each subject during slew, l e v e l walking and slow, l e v e l running under unbraced and braced conditions. Electrogeniametric values were calculated f o r knee flexion-extension, i n t e r n a l - e x t e r n a l r o t a t i o n and varus-valgus. Values were determined f o r each subject from the average of f i v e steps. Tne summary of r e s u l t s f o r Subject A with normal (stable) knees i s presented f o r slow, l e v e l walking (Table 1, Figures 22-A and 22-3) and f o r slow, l e v e l running (Table 2, Figures 23-A and 23-3},.. Values f o r the braced knee were recorded using the Taylor Brace. The r e s u l t s from two subjects (B and C) with abnormal (unstable) knees are presented f o r slow, l e v e l walking (Tables 3 and 5, Figures 24-A, 24-3, 26-A, 26-B) and f o r slow, l e v e l running (Tables 4 and 6, Figures 25-A, 25-B, 27-A, 27-B). A l l braced r e s u l t s were recorded with the Taylor Brace applied. Comparison values from Subject D with an abnormal (unstable) knee are provided f o r slow, l e v e l walking and slow, l e v e l running (Table 7, Figures 28-A, 28-B and Table 8, Figures 29-A and 29-B). A l l braced r e s u l t s were recorded with the use of the Lennox-Hill De-rotational Brace. TABLE I Average values of knee motion (degrees) during slow l e v e l walking f o r Subject A with normal (stable) knees UNBRACED BRACED l e f t knee r i g h t knee l e f t knee r i g h t knee* Flexion-extension 74° 75° 75° 64° Internal-external r o t a t i o n 10° 8° 11° 6° Varus-valgus 15° 12° 15° 7° * indicates knee braced with Taylor Brace TABLE II Average values of knee motion (degrees) during slow l e v e l running f o r Subject A with normal (stable) knees UNBRACED BRACED l e f t knee r i g h t knee l e f t knee r i g h t knee* Flexion-extension 75° 105° 75° 82° Internal-external r o t a t i o n 15° 20° 15° 18° Varus-valgus 15° 20° 16° 17° * i n d i c a t e s knee braced with Taylor Brace 50 40° \I\AAAA\ l e f t knee Flexion Extension / \ i / \*/WV*A. r i g h t knee l e f t knee r i g h t knee 10° 0° 10° l e f t knee r i g h t knee Figure 22-A. Electrogoniomatric t r a c i n g s * of Subject A with normal (stable) knees during unbraced, slow, l e v e l walking. Zero l i n e represents the p o s i t i o n of the knee at n e u t r a l stance. * due to a lack o f c l a r i t y i n the o r i g i n a l , freehand tracings have been used i n some cases. 51 40 v F l e x i o n Intension AAAAA VWUWUU br i ght knee _ J l e f t knee I n t . r o t 1 n _ _ _ J r i g h t knee E x t . r o t ' n l e f t k nee V a r u s I r i g h t knee V a l g u s F i g u r e 22-B E l e c t r o g o n i o m e t r i c t r a c i n g s o f S u b j e c t A w i t h n o r m a l ( s t a b l e ) knee s d u r i n g s l o w , l e v e l w a l k i n g w i t h t h e T a y l o r B r a c e on t h e r i g h t k n e e . Figure 23-A. Electrogoniometric tracings of Subject A with normal (stable) knees during unbraced, slow, l e v e l running. 53 Figure 23-B. Electrcigcniometric tracings of Subject A with normal (stable) knees during slow, l e v e l running with T a y l o r Brace on r i g h t knee. Results Table 1 (walking subject with normal (stable) knees, in a comparison of the unbraced and braced columns, shows a reduction in the range of movement values for the right knee of 11° for flexion-extension (75° to 64°); of 2° for internal-external rotation (8° to 6°) and of 5° for varus-valgus (12° to 7°) following application of the Taylor Brace. The left, unbraced knee range shows a slight increase of 1° in flexion-extension (74° to 75°); an increase of 1° in internal-external rotation (10° to 11°) and remained the same at 15° of varus-valgus movement. Table 2 (running subject with normal (stable) knees), in a comparison of the unbraced and braced columns, shows a reduction in the range of movement values for the right knee of 23° for flexion-extension (105° to 82°); of 2° for internal-external rotation (20° to 18°) and of 3° for varus-valgus (20° to 17°). Tne left, unbraced knee range remained consistent for flexion-extension at 75°, for internal-external rotation at 15° and increased 1° (15" to 16") of varus-valgus movement. The increased speed of ambulation produced a net decrease in the range of flexion-extension for the right, braced knee of 11° (for a slow, level walk), to 23° (for a slow, level run). The net decrease in the range of internal-external rotation and varus-valgus for the right, braced knee remained the same following an increase in the speed of ambulation (2° vs 2° and 5° vs 3°). The magnitude of the recorded values, however, increased from 6° to 18° for internal-external rotation and from 7° to 17° for varus-valgus. The range of movement for the left, unbraced knee after apnlication of the Taylor Brace to the right knee remained consistent (See Table 1). Similarly, when the speed of ambulation increased, there was very l i t t l e change in the range of movement values (Table 2). TABLE I I I Average values of knee motion (degrees) during slow l e v e l walking f o r Subject B with abnormal (unstable) knee UNBRACED BRACED l e f t knee r i g h t knee l e f t knee* r i g h t knee Flexion-extension 80° 79° 66° 80° Internal-external r o t a t i o n 23° 16° 12 16 Varus-valgus 13° 19° 5° 19° * in d i c a t e s knee braced with Taylor Brace TABLE IV Average values of knee motion (degrees) during slow l e v e l running f o r Subject B with abnormal (unstable) knee UNBRACED BRACED l e f t knee r i g h t knee l e f t knee* r i g h t knee Flexion-extension 93° 100° 97° 105° Internal-external r o t a t i o n 25° 25° 16° 31° Varus-valgus 16° 25° 7° 20° * indicates knee braced with Taylor Brace 57 40^ l e f t knee Flexion Extension 10° 0° 10° Int. rot'n Ext. rot'n riq h t knee l e f t knee ri q h t knef l e f t knee right knee Figure 24-A. ;Electrogoniometric tracings of Subject ii with abnormal (unstable) knee during unbraced, slow, l e v e l walking. Zero l i n e represents the position of tne knee at neutral stance. : 58 l e f t knee r i g h t knee r i g h t knee Int. rot'n Figure 24-3. Electrogoniometric tracings of Subject R with abnormal (unstable) knee during slow, l e v e l walking with tlie T aylor 3race on the l e f t knee. 59 Figure 25-A. Elec±rcigoniorretric tracings of Subject B wit-i abnormal (unstable) knee during unbraced, slew, l e v e l running. 60 Flexion Extension l e f t knee i g n t knee Int. r o t Ext. r o t 1 l e f t knee r i c h t knee 10 Varus Valgus' l e f t knee r i g h t knee Figure 25-B, Electrogonioiretric tracings of Subject B with abnormal (unstable) knee during slow, l e v e l ^running with the Taylor Braoe on the l e f t knee. . 61 Results Table 3 (walking subject with abnormal (unstable) knee), i n a comparison of the unbraced and braced columns, shows a reduction i n the range of movement values f o r the l e f t knee of 14° f o r flexion-extension (80° t o 66°); of 11° f o r i n t e r n a l - e x t e r n a l r o t a t i o n (23° t o 12°) and of 8° f o r varus-valgus (13° t o 5°) following a p p l i c a t i o n of the Taylor Brace. The r i g h t , unbraced knee range shows a s l i g h t increase o f 1° i n flexion-extension (79° t o 89°); and maintained tne same values f o r i n t e r n a l - e x t e r n a l r o t a t i o n (16°) and varus-valgus (19°). Table 4 (running subject with abnormal (unstable) knee), i n a comparison of the unbraced and braced columns, shows an increase i n tiie range of movement values f o r the l e f t knee o f 4° f o r flexion-extension (93° t o 97°); a decrease i n the range of i n t e r n a l - e x t e r n a l r o t a t i o n values of 9° (25° t o 16°) and a decrease i n the varus-valgus range o f 9° (16° t o 7°). The r i g h t , unbraced knee range showed an increase of 5° f o r flexion-extension (100° to 105°); an increase o f 6° f o r i n t e r n a l - e x t e r n a l r o t a t i o n (25° t o 31°) and a decrease of 5° f o r varus-valgus (25° to 20°). The range o f flexion-extension o f the l e f t , braced knee was reduced 14° i n a subject walking slowly on the l e v e l . These r e s u l t s are consistent with the r e s u l t s of the normal (stable) knee f o r slow, l e v e l walking where a reduction of 11° was recorded. Increasing the speed of ambulation from a slow, l e v e l walk to a slow, l e v e l run 62 produced an increase in the flexion-extension range of 4 W for the left, braced knee. These results are not consistent with the results from the normal (stable) knee where a decrease of 23° in the flexion-extension range was recorded. There was a consistent net decrease in the range of internal-external rotation for the left, braced knee of 11° for a slow-walking subject and of 9° for a slew-running subject. There was also a consistent net decrease in the range of varus-valgus for the left, braced knee of 8° in a walking subject and of 9° in a running subject. The range of movement of the right, unbraced knee remained the same following application of the Taylor Brace to tlie left knee of the walking subject. An increase in the speed of ambulation, however, to a slow, level run resulted in increases in the range of flexion-extension of 5° (100° to 105°); and in tlie range of internal-external rotation of 6° (25° to 31°). The range of varus-valgus decreased 5° (25° to 20°) for the right, unbraced knee following application of tie Taylor Brace to the left knee of the slow-running subject. 63 TABLE V Average va lues o f knee mot ion (degrees) d u r i n g s lew l e v e l w a l k i n g f o r Sub jec t C w i t h abnormal (unstable) knee UNBRACED BRACED l e f t knee r i g h t knee l e f t knee r i g h t knee* F l e x i o n - e x t e n s i o n 9 0 ° 80° 85° 5 6 ° I n t e r n a l - e x t e r n a l r o t a t i o n 2 0 ° 1 8 ° 2 5 ° 9 ° Varus -va lgus 1 0 ° 1 1 ° 8° 1 0 ° * i n d i c a t e s knee braced w i t h T a y l o r Brace TABLE VI Average va lues o f knee mot ion (degrees) d u r i n g s low l e v e l runn ing f o r Sub jec t C w i t h abnormal (unstable) knee UNBRACED BRACED l e f t knee r i g h t knee l e f t knee r i g h t knee* F l e x i o n - e x t e n s i o n 9 0 ° 8 6 ° 86° 5 9 ° I n t e r n a l - e x t e r n a l r o t a t i o n 2 3 ° 21 30° 11 Varus -va lgus 1 0 ° 11° 7 ° 11° * i n d i c a t e s knee braced w i t h T a y l o r Brace 64 Varus Valgus Int. rot'n Ext. rot'n ^^^^ 1 L v ^ L ! l e f t knee r i g h t knee l e f t knee r i g h t knee Flex i o n Extension 4 il l e f t knee r i g h t knee Figure 26-A. Electrogcniometric t r a c i n g s * of Subject C with abnormal (unstable) knee during unbraced, S l a v , l e v e l walking. Zero l i n e represents the p o s i t i o n of the knee at n e u t r a l stance. Each l i n e represents f i v e degrees o f movement. * o r i g i n a l 65 L e f t knee Varus Valgus r i g h t knee Int. rot'n Ext.rot'n Flexion Extension ; ft... l e f t knee 'HT- . up- r i g h t knee / • -< l e f t knee >., -~ '** - "TV"" '• .;" 'j _\_...... . ... . ./ X . . . ' - j ~ " J . - i 11. 'p V. • / " ' •'*'"' i*.' ' „„ " ; t" r i g h t knee Figure 26^B. Electrogoniometric tracings of Subject C with abnormal (unstable) knee during slow, l e v e l walking with the Taylor Brace on the r i g h t knee. 66 left knee Varus Valgus r i g h t knee Int. rot'n Ext. rot'n Flexion Extension I f . " --•-~_ I V- 111 y; .v.' c. .r "Y"T. " r e : - r v , ^ t r ^ : i : - ^ \l 7- \ - —- U"-A--" - - -'- \ •/ l e f t knee ricrht knee l e f t knee r i q h t knee Figure 27-A. Electrogoniometric tracings o f Subject C witn abnormal (unstable) knee during unbraced, slew, l e v e l running. 67 l e f t knee Varus Valgus v. ' r i g h t knee ."/ \ . : l e f t knee Int. rot'n Ext. rot'n Flexion Extension -cwz^-^w; -/ • r - r - - y - j . • | -j- y..;y i f ^ y •I - v f t " i /...A r i g h t knee l e f t knee r i g h t knee Figure 27-B. Electrogonioiretric tracings of Subject C with abnormal (unstable) knee during slow, l e v e l running with the Taylor Brace on the r i g h t knee. 68 Results Table 5 (walking subject with abnormal (unstable) knee), i n a comparison of the unbraced and braced columns, shows a reduction i n the range o f movement values f o r the r i g h t knee of 24° f o r flexion-extension (80° t o 56°); of 9° f o r i n t e r n a l - e x t e r n a l r o t a t i o n (18° t o 9°) and of 1° f o r varus-valgus (11 t o 10 ) following a p p l i c a t i o n of the Taylor Brace. The l e f t , unbraced knee range shows a s l i g h t decrease of 5° i n flexion-extension, a s l i g h t increase of 5° i n i n t e r n a l - e x t e r n a l r o t a t i o n and a decrease i n varus-valqiis of 2° (10° t o 8°). Table 6 (running subject with abnormal (unstable) knee), i n a comparison of the unbraced and braced columns, shows a decrease i n the range of movement values f o r the r i g h t knee o f 27° f o r flexion-extension (86° t o 59°); o f 10° f o r i n t e r n a l - e x t e r n a l r o t a t i o n (21° t o 11°) and of zero i n the varus-valgus value o f 11°. The l e f t , unbraced knee fluctuated s l i g h t l y following a n p l i c a t i o n of the T a y l o r Brace decreasing 4° i n flexion-extension.(90° to 86°); increasing 7° i n in t e r n a l - e x t e r n a l r o t a t i o n (23° t o 30°) and decreasing 3° i n varus-valgus (10° t o 7°). The range of flexion-extension of the r i g h t , braced knee cons i s t e n t l y decreased from the unbraced range dropping 24° i n the walking subject and 27° i n the running subject. There was a consistent decrease i n the i n t e r n a l - e x t e r n a l r o t a t i o n range of the r i g h t , braced knee of 9° ( f i f t y percent) f o r the walking subject and of 10° (forty-seven peroent) f o r the running subject, f r o n t i e unbraced values. There was very l i t t l e f l u c t u a t i o n i n the magnitude o f the i n t e r n a l - e x t e r n a l r o t a t i o n range, however, keeping constant values despite the increase i n the speed o f ambulation. These r e s u l t s were consistent with the r e s u l t s o f Subject B who showed decreases o f forty-seven percent and t a i r t v - s i x percent res p e c t i v e l y i n i n t e r n a l - e x t e r n a l r o t a t i o n values f o r the braced knee. The varus-valgus values of the r i g h t knee fluctuated ver/ l i t t l e a f t e r bracing, reducing only 1° during slow, l e v e l walking and remaining the same during slow, l e v e l running. TABLE VII Average values of knee motion (degrees) during slaw level walking for Subject D with abnormal (unstable) knee UNBRACED BRACED l e f t knee r i g h t knee l e f t knee r i g h t knee* Flexion-extension 85° 79° 85° 60° Internal-external r o t a t i o n 15° 27° 13° 5° Varus-valgus 13° 8° 15° 7° * indicates knee braced with Lennox-Hill De-rotational Brace TABLE V I I I Average values of knee motion (degrees) during slow l e v e l running f o r Subject D with abnormal (unstable) knee UNBRACED BRACED l e f t knee right knee l e f t knee right knee* Flexion-extension 95° 96° 85° 69° Internal-external rotation 20° 28° 18° 10° Varus-valgus 14° 11° 16° 7° * i n d i c a t e s knee braced with Lennox-Hill De-rotational Brace 71 Figure 28-A. Elec±rogoniometric tracings of Subject D with abnormal (unstable) knee during unbraced, slow, l e v e l walking. Zero l i n e represents the p o s i t i o n of the knee a t n e u t r a l stance. Each l i n e represents f i v e degrees of movement. 72 ^ ^ ^ ^ ; M ; ^ , I I , I , ^ ) ) , , , , , , , rot'n^o rot'n .. . . ... on ^ ^ ^ ' ' ' ^ ' V f ' " " • I ' l ^ " * ' ! ' ! ! ! ^ ! ! ! ! H i l l 7 sion eft knee Lght knee / —-V-- left knee riant knee / / _ " \ • t — l e f t knee riaht knee Figure 28-B. Electrogoniometric tracings of Subject D with abnormal (unstable) knee during slow, level walking with the Lennox-Hill De-rotational Brace cn the right knee. Figure 29-A. Hlectrogoniometric tracings of Subject D with abnormal (unstable) knee during unbraced, slow, l e v e l running. 74 jus rot'n rot n o x ion ension l e f t knee r i a n t knee l e f t knee r i g h t knee l e f t knee r i g h t knee Figure 29-B. Electrogoniometric tracings of Subject D with abnormal (unstable) knee during slow, l e v e l running with the Lennox-Hill De-rotational Brace on the r i g h t Jcnee. 75 Results Table 7 (walking subject with abnormal (unstable) knee), i n a comparison of the unbraced and braced columns, shows a reduction i n the range of movement values f o r the r i g h t knee of 19° f o r flexion-extension (79° t o 60°); of 22° f o r i n t e r n a l - e x t e r n a l r o t a t i o n (27° t o 5°) and o f 1° f o r varus-valgus (8° t o 7°) following a p p l i c a t i o n of the Lennox-Hill De-rotation Brace. The l e f t , unbraced knee range values remained constant f o r flexion-extension at 85°; decreased 2° f o r i n t e r n a l - e x t e r n a l r o t a t i o n (15° t o 13°) and increased 2° f o r varus-valgus (13° to 15°). . Table 8 (running subject with abnormal (unstable) knee), i n a comparison of the unbraced and braced columns, shows a decrease i n the range of movement values f o r the r i g h t knee of 27° f o r flexion-extension (96° t o 69°); a decrease of 18° f o r i n t e r n a l - e x t e r n a l r o t a t i o n (28° t o 10°) and a decrease of 4° f o r varus-valgus (11° t o 7°). The l e f t , unbraced knee values fl u c t u a t e d following a p p l i c a t i o n o f the Lennox-Hill De-rotation Brace, decreasing 10° i n flexion-extension (95° t o 85°); decreasing 2° i n i n t e r n a l - e x t e r n a l r o t a t i o n (20° t o 18°) and increasing 2° (14° t o 16°) i n varus-valgus movement. The range o f flexion-extension of the r i g h t , braced knee co n s i s t e n t l y decreased from the unbraced range dropping 19° i n the walking subject and 27° i n the running subject. The reduction i n the recorded values f o r i n t e r n a l - e x t e r n a l r o t a t i o n were the greatest f o r the walking subject at 22° (eighty-one percent) and were reduced to 18° ( s i x t y - f o u r percent) i n the running subject. Varus-valgus values f l u c t u a t e d very l i t t l e i n creasing 1° during walking and 4° during running. Walking with the Lennox-Hill De-rotational Brace on the r i g h t knee o f Subject D d i d not g r e a t l y a l t e r the range of the c o n t r a - l a t e r a l knee. Running, however, decreased flexion-extension by 10°, decreased i n t e r n a l - e x t e r n a l r o t a t i o n by 2° and increased varus-valgus , _.o by 2 . Discussion A l l subjects tested with the Taylor Brace under conditions of slow, l e v e l walking showed an o v e r a l l reduction i n the range o f flexion-extension of the braced knee (Subject A, 11°; Subject B, 14°; Subject C, 24°). Increasing the speed of ambulation t o a slow, l e v e l run produced a f u r t h e r decrease i n the flexion-extension range of the braced knee (Subject A, 23°; Subject C, 27°), with the exception of Subject B who recorded an increase of 4°. Results from Subject D (Lennox-Hill De-rotational Brace) showed s i m i l a r findings with decreases of 19° f o r slow, l e v e l walking and 27° f o r slow, l e v e l running. With the exception of Subject B (for slow, l e v e l running), i t appears that the Taylor Brace i s having a r e s t r a i n i n g e f f e c t on the dynamic flexion-extension range of the braced knee that increases i n magnitude as the speed of ambulation increases. This e f f e c t i s s i m i l a r i n magnitude to the reduction produced by the Lennox-Hill 77 De-rotational Brace. A l l subjects tested with the T a y l o r Brace under conditions of slow, l e v e l walking shewed an o v e r a l l reduction i n the range of i n t e r n a l - e x t e r n a l r o t a t i o n of the braced knee (Subject A, 2°; Subject 3, 11°; Subject C, 9°). Increasing the speed of ambulation t o a slow, l e v e l run produced minor f l u c t u a t i o n s i n the i n t e r n a l - e x t e r n a l r o t a t i o n range o f the braced knee (Subject B, 9°; Subject C, 10°) with the exception of Subject A who remained the same at 2°. Results from Subject D (Lennox-Hill De-rotational Brace) showed s i m i l a r findings with decreases f o r i n t e r n a l - e x t e r n a l r o t a t i o n of 22° f o r slow, l e v e l walking and 18° f o r slow, l e v e l running. With the exception of Subject A (normal, stable knee) i t appears that the Taylor Brace i s having a r e s t r a i n i n g e f f e c t on the dynamic i n t e r n a l - e x t e r n a l r o t a t i o n range of the braced knee. This r e s t r a i n i n g e f f e c t i s constant (with minor fluctuations) despite increases i n the magnitude of the r o t a t i o n measurements as a r e s u l t of increases i n the speed of ambulation. A p p l i c a t i o n of the T a y l o r Brace t o the abnormal (unstable) knees o f Subjects B and C reduced, the high rotatory values f o r slow, l e v e l walking to w i t h i n the range recorded from the normal (sta b l e ) , unbraced knee (Subject A) f o r slow, l e v e l walking. This e f f e c t i s s i m i l a r i n magnitude t o the reduction produced by the Lennox-Hill De-rotational Brace on i n t e r n a l - e x t e r n a l r o t a t i o n . A l l subjects tested with the Taylor Brace under conditions o f slow, l e v e l walking showed an o v e r a l l reduction i n the range of varus-valgus of the braced knee (Subject A, 5yJ; Subject B, 8W; Subject C, 1°). Increasing the speed o f ambulation t o a slow, l e v e l run produced s i m i l a r decreases i n the varus-valgus range of the braced knee (Subject A, 3°; Subject B, 9°), with the exception of Subject C who recorded no change. Results from Subject D (Lennox-Hill De-rotational Brace) shaved s i m i l a r findings with decreases o f 1° f o r slow, l e v e l walking and 4° f o r slow, l e v e l running. With the exception o f Subject C, i t appears t h a t the Taylor Brace i s having a r e s t r a i n i n g e f f e c t an the dynamic varus-valgus range o f the braced knee. In one subject (B), t h i s r e s t r a i n i n g e f f e c t increased i n magnitude with the speed of ambulation. The r e s u l t s from Subject B are s i m i l a r t o the reduction produced by the Lennox-Hill De-rotational Brace on varus-valgus. A p p l i c a t i o n o f the Taylor Brace under conditions of slow, l e v e l walking produced minor f l u c t u a t i o n s i n the range o f the c o n t r a - l a t e r a l (unbraced) knee (Subject A, 1° flexion-extension, 1° i n t e r n a l - e x t e r n a l r o t a t i o n ; Subject B, 1° flexion-extension) with the exception o f Subject C who recorded major f l u c t u a t i o n s i n the range o f a l l three movement parameters. Increasing the speed o f ambulation to a slow, l e v e l run produced major f l u c t u a t i o n s i n the range o f the c o n t r a - l a t e r a l (unbraced) knee (Subject B, Subject C) with the exception of Subject A who recorded minor f l u c t u a t i o n s o f 1° i n the varus-valgus range. Results from Subject D (Lennox-Hill De-rotational Brace) showed s i m i l a r findings with minor f l u c t u a t i o n s f o r slow, l e v e l walking and major fluctuations for slow, level running. With the exception of Subject C, i t appears that the Taylor Brace os having very l i t t l e effect on the dynamic range of the contra-lateral (unbraced) knee for slow, level walking. Increasing the speed of ambulation to a slow, level run appears to produce major fluctuations in the range of the contra-lateral knee for both subjects with unstable knees (Subjects B and C). This effect i s similar to the fluctuations produced by the Lennox-Hill De-rotational Brace. Instant Center of Rotation Data was collected for each subject from the unstable knee under unbraced and braced conditions. A to t a l of six roentgenograms were taken and the instant center calculated for the series from ninety degrees of flexion to zero degrees of flexion. Each subject assumed a position lying on the side with the selected knee non-'weight- bearing. The summary of results i s presented for the instant center of rotation pathways (Figures 30 and 31).. Joint surface velocity angles are shown for the six calculated instant centers for each subject from zero degrees of flexion (number six) to ninety degrees of flexion (number one) Tables 9-A, 9-3, 10-A and 10-B). 80 l i i • '.6 I unbraced circle diameter 4.6 centimeters braced circle diameter 3.5 centimeters Figure 30. Pathway of instant center of rotation with respect to the tibia and femur for Subject B, left knee, unstable. Scale is approximately one third. 8 1 Angle of J o i n t 9 0 ° 7 5 ° 6 0 ° 4 0 ° 2 0 ° • 1 0 ° VelocityAngle (unbraced) 9 0 ° 7 6 ° 1 0 7 ° 9 0 ° 8 8 ° 9 0 ° Table 9-A. J o i n t surface v e l o c i t y angles, Subject B, unstable knee, unbraced. .Angle of ^ Q O J o i n t 7 5 ° 6 0 ° 4 0 ° 2 0 ° 1 0 ° V e l o c i t y A n g l e g 8 o (braced) 9 0 ° 9 6 ° 9 0 ° 9 4 ° 9 0 ° Table 9-B. J o i n t surface v e l o c i t y angles, Subject B, unstable knee, braced. unbraced circle diameter 1.65 centimeters i vi braced circle diameter 2.20 centimeters Figure 31. Pathway of instant center of rotation with respect to tlie tibia and femur for Subject C, right knee, unstable. Scale is approximately one third. 83 Angle of 9 Q o Joint 75° 60° 40° 20° 10° Velocity Angle^o (unbraced) 90° 90° 90° 107° 96° Table 10-A. Joint surface velocity angles, Subject C, unstable knee, unbraced. Angle of 90° Joint 75° 60° 40° 20° 10° Velocity Angle^o (braced) 90° . 90° 91° 116° 90° Table 10-B. Joint surface velocity angles, Subject C, unstable knee, braced. Results Results from both subjects (Figures 30 and 31) shew that the instant centers for the six .different knee angles are located i n the posterior portion of the medial femoral condyle. The results also show that there i s no standard pattern to the instant center pathway for the abnormal, unbraced knee. The instant center movement in the posterior portion of the medial femoral condyle i s quite random. There was a tendency for the instant center pathway to move posteriorly and superiorly following application of the Taylor Brace that was consistent for both subjects. For Subject B, the location of the instant center for the six different knee angles f e l l within a c i r c l e with a diameter of 4.60 centimeters. Following application of the Taylor Brace, the c i r c l e diameter was reduced to 3.50 centimeters. These findings were not consistent with Subject C who showed an increase in c i r c l e diameter from 1.65 centimeters to 2.20 centimeters following application of the Taylor Brace. The joint surface velocity angles were judged to Joe abnormal in both of the subjects tested. Subject B showed abnormal velocity angle values with impingement to flexion between sixty and seventy-five degrees inclusive (Table 9-A). Application of the Taylor Brace to Subject B resulted in values indicative of relatively free gliding at the articular surfaces with no restriction to flexion (Table 9-B). Subject C showed relatively free knee motion throughout the entire unbraced range except f o r the l a s t few degrees of extension where abnormal values were noted (Table 10-A). A p p l i c a t i o n o f the Taylor Brace increased the abnormal values i n t h i s range. Discussion Both subjects tested with the Taylor Brace located the i n s t a n t center of r o t a t i o n pathway i n the p o s t e r i o r o o r t i o n of the medial femoral condyle. These r e s u l t s are consistent with the findings o f r e l a t e d researchers (Frankel and Burstein, 1971; Smidt, 1972; Meek, Martens and Temets, 1975). There appears to be no set pattern to t h i s pathway f o r the abnormal (unstable) knee but, rather, random movement on the condylar surface. Meek e t a l (1975) and Walker (1973) have reported s i m i l a r r e s u l t s f o r abnormal knee pathways. For both o f the subjects tested, the i n s t a n t center pathway moved p o s t e r i o r l y and s u p e r i o r l y following a p p l i c a t i o n o f the Taylor Brace. Both of the subjects tested shewed an a l t e r a t i o n i n the pattern and c i r c l e diameter of the i n s t a n t center o f r o t a t i o n pathway a f t e r a p p l i c a t i o n o f the Taylor Brace. There was not, however, any consistency i n the patterns o f any subject nor i n tne change of c i r c l e diameter. Subject B recorded a decrease i n c i r c l e diameter while Subject C recorded an increase following bracing. I t appears that a p p l i c a t i o n of the Taylor Brace t o the unstable knee produces changes i n the pattern and dispersion of the i n s t a n t center of r o t a t i o n pathway that has no d e f i n i t e trend. There does appear, however, t o be a d e f i n i t e s h i f t i n g o f the i n s t a n t center pathway p o s t e r i o r l y and s u p e r i o r l y following bracing. Both subjects tested showed abnormal j o i n t surface v e l o c i t y angles (Tables 9-A and 10-A). Appl i c a t i o n o f the Taylor Brace to Subject B showed changes i n the abnormal j o i n t surface v e l o c i t y angle values t o values i n d i c a t i v e o f smooth, normal movement a t the a r t i c u l a r surfaces (Table 9-B). A p p l i c a t i o n o f the Taylor Brace t o Subject C r e s u l t e d i n an increase i n already abnormal values f o r the l a s t few degrees of extension (Table 10-B). This increase may be exolained by r o t a t i o n of the t i b i a as a r e s u l t of the screw-home mechanism of the knee. During the l a s t few degrees of extension, t i b i a l r o t a t i o n projects points on a d i f f e r e n t plane, not representing a true l a t e r a l roentgenogram. The r o t a t i o n of the. t i b i a at t h i s p o i n t was s i g n i f i c a n t enough t o produce i n c o r r e c t p r o j e c t i o n of the i n s t a n t center from points not on the midline. The use.of points on the midline o f the t i b i a l s h a f t rather than on the margins f o r the p r o j e c t i o n of the ins t a n t center would produce a more accurate c a l c u l a t i o n . Except f o r t h i s impingement i n the l a s t few degrees of extension, Subject C demonstrates free g l i d i n g a t the a r t i c u l a r surfaces. I t appears that a p p l i c a t i o n o f the Taylor Brace to the unstable knee produces changes i n abnormal j o i n t surface v e l o c i t y angles t o within the normal range. With the exception of Subject C in'the l a s t few degrees of extension, these changes are i n d i c a t i v e of r e l a t i v e l y free g l i d i n g at the a r t i c u l a r surfaces, throughout the monitored range, increases in abnormal values for Subject C can be explained by the presence of tibial rotation and the use of points away from the midline causing miscalculation of the instant center for that particular segment. Stress Analysis Mechanical stresses were applied to the knee joint by means of a stress machine. Data was collected for each subject from the unstable knee. Roentgenograms were taken and the amount of medial and anterior laxity determined for unbraced and braced conditions. The summary of results is presented below for medial laxity (Table 11) and anterior laxity (Table 12). A l l values for the braced knee were recorded using the Taylor Brace. TABLE 11 Medial Laxity* Subject Unbraced Unstressed Unbraced Stressed Braced Stressed B 0.70 cms. 0.90 cms. 0.80 cms. C 0.45 cms. 0.90 cms. 0.90 cms. * a l l measurements of medial laxity were made in millimeters of distance between the sub-chondral bone of the medial femoral condyle and the sub-chondral bone of the medial tibial condyle at a distance one centimeter from the medial margin of the proximal tibia. 88 TABLE 12 Anterior Laxity Subject Unbraced Unstressed Unbraced Stressed Braced Stressed B 6.40 ens. 7.80 cms. 6.90 cms. C 7.35 cms. 8.95 cms. 7.50 cms. Tie overall effect of the Taylor Brace on anterior laxity can be seen in Table 13. TABLE 13 Anterior Laxity Reduction Values Subject unbraced braced reduction percentage B C 1.40 cms. 1.60 cms. 0.50 cms. 0.15 cms. 0.90 cms. 1.45 cms. 64 90 Results Table 11 (nedial laxity), in a.comparison of tlie unbraced, unstressed and unbraced, stressed columns shows a range of medial laxity for the two subjects of 0.20 centimeters to 0.45 centimeters. Application of the Taylor Brace to the unstable knee of.Subject S produced a reduction in the medial l a x i t y measurement of 0.10 centimeters ( f i f t y percent) while Subject C remained the same. Table 12 (anterior l a x i t y ) , i n a comparison o f the unbraced, unstressed and unbraced, stressed columns sho/vs a range of a n t e r i o r l a x i t y f o r the two subjects of 1.40 centimeters to 1.60 centimeters. App l i c a t i o n of the Taylor Brace to the unstable knee produced a reduction i n the a n t e r i o r l a x i t y measurements of both subjects; o f Subject B by 0.50 centimeters ( s i x t y - f o u r percent) and of Subject C by 1.45 centimeters (ninety percent) (Table 13). Discussion The range o f medial l a x i t y f o r t h i s sample was 0.20 centimeters to 0.45 centimeters. Subject B with a medial l a x i t y measurement o f 0.20 centimeters i s below the values reported by Kennedy and Fowler (1971) and Roser e t a l (1971) f o r unstable knees. Subject C with a medial l a x i t y measurement of 0.45 centimeters was within t h e i r reported range. Both subjects tested with the Taylor Brace under conditions of medial stress shaved minor or n e g l i g i b l e changes i n the medial l a x i t y range. These r e s u l t s are consistent with the s t r e s s analysis findings of Roser e t a l (1971) who reported reductions o f 0.30 centimeters and increases of 0.10. centimeters i n medial i n s t a b i l i t y f o l l a v i n g a p p l i c a t i o n of the Palmer Knee Brace to the unstable knee. With the exception of Subject B who shaved a decrease of 0.10 centimeters, i t appears that the Taylor Brace is having l i t t l e or no effect on the nedial laxity of the unstable knee.^ The range of anterior laxity for this sample was 1.40 centimeters to 1.60 centimeters. These values are within the range rctx)rted by Kennedy and Fowler (1971) for abnormal knees. Both subjects tested with the Taylor Brace under conditions of anterior stress displayed major decreases in the anterior laxity range (Table 13). The values demonstrated here are within those found by Poser et al (1971) who reported reductions of 0.30 centimeters to 0.50 centimeters in anterior laxity following application of the Taylor Brace. From the results of both subjects, i t appears that the Taylor Brace is producing a substantial decrease in the anterior laxity of the stressed knee. Subjective Evaluation Subjective evaluation of tlie Taylor Brace consisted of a verbal discussion with the subject following each session of physical activity, as well as an overall written assessement. Both the discussion and assessement were based on pre-determihed criteria. Subject A wore the Taylor Brace while narticinating in the following activities; rugby, cycling, volleyball, distance running, sprinting and weight lifting. These are his comments: "The most impressive thing about this brace is the joint. It fits closely to tlie leg and can do anything the normal knee does. Even deep knee bends are easily done. The brace was easily applied and f i t snugly. I t gave the Immediate impression of s t a b i l i t y . There was soma i n i t i a l i r r i t a t i o n along the front of the t i b i a and behind the knee on the tendon of biceps, from rubbing on the c u f f s . The thigh and c a l f c u f f s f i t w e l l but soon began t o get s l i p p e r y because of sweat b u i l d i n g up i n s i d e . With prolonoued use the medial knee strap and c u f f s began t o s l i p down the l e g . 'During t h i s slippage the j o i n t s t i l l a r t i c u l a t e d w e l l but the cu f f s dug i n t o the thigh and shin making movement d i f f i c u l t . There was never any c o n s t r i c t i o n or numbness i n the l e g to hamper movement despite prolongued use of over three hours on occasion. The brace was so l i g h t that a f t e r a while one forgot that there was anything at a l l on the knee." Subject B wore the Taylor Brace while p a r t i c i p a t i n g i n the f o l l a v i n g a c t i v i t i e s ; squash, handball, v o l l e y b a l l , c y c l i n g , alpine s k i i n g , i n t e r v a l running and tree p l a n t i n g . These are h i s comments: "The a r t i c u l a t i o n of the j o i n t was ex c e l l e n t . The range of motion was i n no way hampered i n e i t h e r f l e x i o n or extension. The f i b e r g l a s s thigh and c a l f c u f f s had a tendency to jab i n t o the thigh at some points and pinch behind the knee and along the t i b i a l snine. The s t i f f f i b e r g l a s s (of t i e thigh cuff) would not conform to the changing upper leg muscles and tended to s l i p down the l e g . The medial support strap had a tendency to s l i p down with a c t i v e use. Because of the design, the p o p l i t e a l region behind the knee was never s e r i o u s l y occluded. The weight of t i e brace (.75 kilograms) was not noticeable and d i d not hamper movement. Appl i c a t i o n of the brace was quick and simple. Subject C wore tlie T a y l o r Brace while p a r t i c i p a t i n g i n the following a c t i v i t i e s ; squash, rugby t r a i n i n g sessions, slow jogging. These are h i s ccmrients: "When I f i r s t began t o use the brace i t was a b i t uncomfortable, e s p e c i a l l y at the back o f the knee (long head o f biceps) and on the shin. A f t e r a while t h i s a l l went away. The j o i n t moved w e l l . There was never any r e s t r i c t i o n to movement at a l l . There was a d e f i n i t e movement o f tine brace down the l e g with active use and frequent adjustements were necessary. 'The f i t was snug, the device l i g h t and i t never f e l t r e s t r i c t i n g or uncomfortable, a f t e r the i n i t i a l wearing i n . You could even wear i t under the pants without i t being noticeable. Discussion A l l subjects s u b j e c t i v e l y evaluated following active use o f the Taylor 3race reported the following major points: (a) e x c e l l e n t j o i n t a r t i c u l a t i o n range even a f t e r displacement of the j o i n t from the knee area. (b) i r r i t a t i o n from the f i b e r g l a s s c u f f s on the skin, e s p e c i a l l y i n the region of the long head o f biceps and along tlie a n t e r i o r surface o f the t i b i a l s h a f t . (c) lack of.conformity o f the r i g i d f i b e r g l a s s thigh c u f f to the changing quadriceps muscle mass. (d) d e f i n i t e slippage of the thigh and c a l f c u f f s and medial support strap down the l e g with a c t i v e use. 93 (e) ease of a p p l i c a t i o n . (f) l i g h t weight, not bulky. (g) comfort of f i t with no pinching or binding a f t e r the i n i t i a l , wearing-in period. (h) no c o n s t r i c t i o n or numbness of the leg r e s u l t i n g i n r e s t r i c t i o n s to movement. CHAPTER V SUMMARY AND CONCLUSIONS Summary The purpose o f t h i s study was to determine the e f f e c t of tlie Taylor Brace on the s t a b i l i t y and dynamic range o f motion of the knee j o i n t . Tiie study was divided i n t o an analysis o f the Taylor Brace under the following experimental conditions; (a) electrogoniometric t e s t i n g , (b) i n s t a n t center o f r o t a t i o n c a l c u l a t i o n , (c) s t r e s s analysis and (d) subjective evaluation. Electrogoniometric t e s t i n g consisted o f recordings of knee movement i n three mutually perpendicular movement parameters of flexion-extension, i n t e r n a l - e x t e r n a l r o t a t i o n and varus-valgus f o r the unstable knee. Testing was conducted i n a l e v e l segment of hallway f o r t y meters long. Experimental runs consisted of ten steps, exclusive of the f i r s t and l a s t steps.of the run, f o r unbraced and braced conditions. Instant center o f r o t a t i o n c a l c u l a t i o n was c a r r i e d out through roentgenogram measurement of the unstable knee. With the femur f i r m l y f i x e d t o the x-ray table, the t i b i a was manually moved. Seven medial roentgenograms were taken of the knee from ninety degrees of f l e x i o n t o zero degrees of f l e x i o n i n increments of f i f t e e n t o twenty degrees. The i n s t a n t center of r o t a t i o n was c a l c u l a t e d f o r each x-ray f o r unbraced and braced conditions. Stress analysis was c a r r i e d out on the unstable knee using a mechanical st r e s s apparatus. Pegulated forces were applied to the knee and radiographic changes i n the l a x i t y of the knee j o i n t recorded f o r unbraced and braced conditions. Medial and a n t e r i o r l a x i t y measurements were made f o r unbraced, unstressed; unbraced, stressed; and braced and stressed conditions. Subjective evaluation consisted of verbal evaluation of the brace function a f t e r periods o f p h y s i c a l a c t i v i t y as w e l l as an o v e r a l l w r i t t e n assessement at the conclusion of the study. Both parts of the subjective evaluation were based on pre-determined c r i t e r i a . S l e c t r o g o n i a n e t r i c r e s u l t s i n d i c a t e d a general reduction i n the dynamic flexion-extension, i n t e r n a l - e x t e r n a l r o t a t i o n and varus-valgus range of the braced knee following a p p l i c a t i o n o f the Taylor Brace to the walking subject. The r e s t r a i n t on the dynamic flexion-extension range was considered undesirable but not s i g n i f i c a n t i n a l t e r i n g the t o t a l g a i t pattern. Reduction of i n t e r n a l - e x t e r n a l r o t a t i o n and varus-valgus values, however, were considered to be important factors i n the brace's a b i l i t y to r e s t r a i n undesirable motions. Hie movement parameters of the unbraced knee showed some fl u c t u a t i o n s i n the magnitude of the range following a p p l i c a t i o n of the Taylor Brace to the c o n t r a - l a t e r a l knee. These f l u c t u a t i o n s were minor i n the walking 96 subject with a tendency t o increase i n magnitude as the speed o f ambulation increased. Instant center o f r o t a t i o n c a l c u l a t i o n located the i n s t a n t center of r o t a t i o n pathway i n the region o f the medial femoral condyle. There was no s e t pattern t o the pathway. A p p l i c a t i o n of the Taylor Brace produced changes i n the pathway pattern and d i s t r i b u t i o n (diameter) but no trends were evident. Abnormal j o i n t surface v e l o c i t y angles shaved d e f i n i t e a l t e r a t i o n s to normal values, i n d i c a t i v e o f free g l i d i n g at the a r t i c u l a r surfaces, f o l l a v i n g a p p l i c a t i o n of the Taylor Brace to the unstable knee. There were very l i t t l e changes i n the medial l a x i t y measurements of the unstable knees f o l l a v i n g a p p l i c a t i o n of the T a y l o r Brace to the stressed knee. I t was f e l t that t h i s was due i n p a r t t o both subjects having r e l a t i v e l y stable medial s t r u c t u r e s . A n t e r i o r l a x i t y values showed marked decreases by as much as ninety percent i n one subject following bracing with the T a y l o r Brace. Subjective evaluation showed e x c e l l e n t range and a r t i c u l a t i o n o f the Taylor Brace j o i n t with very l i t t l e r e s t r i c t i o n t o movement. Subjects found the brace lightweight, easy t o apply, n o n - r e s t r i c t i n g and comfortable to wear. Oi^servations were made that the c u f f s and medial strap d i d tend to s l i p down the l e g with active use and that there were sane i n i t i a l pressure areas along the a n t e r i o r surface o f the t i b i a l s h aft and the tendon of the long head o f biceps. The r i g i d structure o f ; the thigh c u f f was not accomodating enough to the changing quadriceps muscle mass during a c t i v e use. 97 Conclusions 1. The Taylor Brace has a r e s t r a i n i n g e f f e c t on the dynamic flexion-extension range of the braced knee that increases with tlie speed of ambulation. This r e s t r a i n i n g e f f e c t i s considered undesirable but not s i g n i f i c a n t i n a l t e r i n g tlie t o t a l g a i t pattern. 2. The Taylor Braos has a r e s t r a i n i n g e f f e c t on the dynamic i n t e m a l - e x t e m a l r o t a t i o n and varus-valgus range of the braced knee that remains constant with increases i n the speed of ambulation. The brace's a b i l i t y t o r e s t r a i n those'-undesirable motions i s considered an important factor. 3. A p p l i c a t i o n of the Taylor Braoe to the knee produces changes i n the movement patterns o f the c o n t r a - l a t e r a l , unbraced knee. 4. Changes i n the pattern and d i s p e r s i o n of the i n s t a n t center of r o t a t i o n pathway occurrs following bracing with the Taylor Brace but no d e f i n i t e trends are evident. 5. There i s no recordable reduction i n medial l a x i t y measurements following a p p l i c a t i o n of the Taylor Brace to the unstable knee. I t was f e l t that t h i s was due i n most p a r t t o both subjects having sound medial structures. A n t e r i o r l a x i t y , however, was g r e a t l y reduced i n the unstable knee following bracing. 6. J o i n t a r t i c u l a t i o n range of the Taylor Brace i s considered to be e x c e l l e n t with comfortable f i t . Slippage of tlie brace i s considered to be a s i g n i f i c a n t problem as w e l l as the r i g i d nature of the f i b e r g l a s s thigh c u f f construction. 98 CHAPTER VI RECENT DEVELOPMENTS AND SUGGESTIONS FOR FURTHER RESEARCH New Prototypes Since the development of the f i r s t prototype (Prototype I ) , continuing research has been c a r r i e d out on the Taylor Brace. From subjective evaluation and continuing subject use, s e v e r a l refinements have been made i n the brace design to enhance comfort and f i t . Figure 32. Prototype I, Taylor Brace. Arrows i n d i c a t e s p l i t medial strap and d i r e c t i o n of a p p l i c a t i o n . Note the polyester r e s i n thigh and c a l f c u f f s . 99 A B D Ficnire 33. Tnylor Brace, prototvPe I I , (A to E). Arrows indicate s p l i t media] strap and d i r e c t i o n of application ( A ) . Note the replacement of "D" hooks by velcro straps (I)) and tlie incorporation of s p i r a l webbinn to fasten tlie brace to the leg. P r i n t E shows the brace cuffs with the webbing removed. Into that the size of the thigh cuff has been reduced to h a l f the previous size and the rxjlynropylene material -used in cuff construction. 100 ii c Figure 34. Taylor Brace, Prototype III , (A to 12) . Arrows indicate single nedial strap and d i r e c t i o n of anolication. Note the medial strao continues up the log to form the webbed thigh fastener (A) , anterior view. The metal j o i n t surface has been oadded with f e l t for a t h l e t i c competition (13), l i t e r a l view. The p o p l i t e a l region of the knee i s s t i l l free (C), posterior view. P r i n t E shows the brace cuffs with the webbing removed. Jote the c a f f sizes are the sane as Prototype II and the d i f f e r e n t material, ortholene, used in cuff c o n s t r i c t i o n . 101 102 Figure 36. J o i n t Fixation. (A) mechanical brace j o i n t positioned; (B) assembly base with uncut geometry, too view; (C) assembly base, bottom view, snowing suction cups; (D) assembly base, side view. To ensure proper nosition of the mechanical brace j o i n t near the anatomical knee j o i n t and prevent slippage with active use, suction cups have been applied with skin cerent to the skin at the knee. 103 Suggestions for Further Research The following topics are suggested as continuing areas of research: 1. Standardization and classification of tyoical stable and unstable knee patterns for varying rates of ambulation. 2. Association of specific structural lesions of the knee with specific characteristics of gait. 3. The use of cinematography in conjunction with electrogoniometry in the analysis of knee function under various conditions. 4. Correlation of electromyography with electarogmiometry of leg function. 5. Electaxjoniometric evaluation of specific sport activities, both indoor and outdoor, with relation to joint function. 6. Investigation of the use of the Taylor Brace joint design in the cast-brace treatment of tibial fractures. 104 BIBLIOGRAPHY Cousins, S.J., A Parallelogram Chain Designed to Measure Human Joint Motion, Unpublished Masters Thesis, Department of Mechanical Engineering, University of British Columbia, Canada, 1975. Eriksson, E., Sports Injuries of the Knee Ligaments: Their Diagnosis, Treatment, Rehabilitation, and Prevention, Medicine and Science in Sports, Vol. 8, No. 3: 133-144, 1976. Frankel, V.H., Burstein, A.H. and Brooks, D.B., Biomechanics of Internal Derangement of tlie Knee, Journal of Bone and Joint Surgery, Vol. 53-A, No. 5: 915-962, 1971. Gollnick, P.D. and Karpovich, P.V., Electrogoniometric Study of Locomotion and of Same Athletic Movements, The Research Quarterly, Vol. 35, No. 3: 357-369, 1962. Hallen, L.G., The "Screw-Home'1 Movement in the Knee Joint, Acta Orthop. Scandia, 37: 97-106, 1966. Helfet, A.J., Disorders of the Knee, J.B. Lippincott Company, Philadelphia, U.S.A., 1974. Helfet, A.J., Mechanism of Derangements of the Medial Semilunar Cartilage and their Management, Journal of Bone and Joint Surgery, 41-B: 319-336, May, 1959. Hughston, J.C., Andrews, J.R., Cross, M.J. and Moschi, A., Classification of Knee Ligament Instabilities Part I. The Medial Compartment and Cruciate Ligaments, Journal of Bone and Joint Surgery, 58-A, No. 2: 159-172, March, 1976. Hughston, J.C., Andrews, J.R., Cross, M.J. and Moschi, A., Classification of Knee Ligament Instabilities Part II. The Lateral Comnartment, Journal of Bone and Joint Surgery, 58-A, Mo. 2: 173-179,-March, 1976. Jesswein, P.O., Lower Extremity Orthotics III, VAPC Research, Bulletin of Prosthetics Research, pp. 261-262, Fall, 1966. Johnston, R.C., Measurement of Hip Joint Motion During Walking: An Evaluation of Electrogoniometric Method, Journal of Bone and Joint Surgery, 51: 1083, 1969. 105 Karpovich, P.V., Electrogonicmetrie Study of J o i n t s , U.S. Armed Forces Medical Journal, 11: 424, 1960. Kennedy, J.C. and Fowler, P.J., Medial and Ant e r i o r I n s t i b i l i t y of the Knee, Journal of Bone and J o i n t Surgery, V o l . 53-A, Mo. 7: 1257-1270, 1971. Kennedy, J . C , Weinberg, H.W. and Wilson, A.S., The Anatomy and Function o f the Anterior Cruciate Ligament, Journal o f Bone and J o i n t Surgery, V o l . 56-A, No. 2: 223-235, 1974. Kettlekamp, D.B., Johnson, R.J., Smidt, G.L., Chao, E.Y.S. and Walker, M., An Electrogoniometric Study o f Knee Motion i n Normal Gait, Journal of Bone and J o i n t Surgery, 52: 775-790, 1970. 1 : ' Lamoreux, L.W., Kinematic Measurements i n the Study of Human Walking, B u l l e t i n o f Prosthetics Research, pp. 3-81, Sprinq, 1971. Laubenthal, K.N., Smidt, G.L. and Kettlekamp, D.B., A Quantitative Analysis o f Knee Motion During A c t i v i t i e s o f Da i l y L i v i n g , P h y s i c a l Therapy Journal, V o l . 52, No. 1: 34-42̂  January, 1972. Lehmann, J.F., Warren, C G . and DeLateur, B.J., A B.iomechanical Evaluation of Knee S t a b i l i t y i n Below-Knee Braces, Archives o f P h y s i c a l Medicine and R e h a b i l i t a t i o n , pp. 688-695, December, 1970. Meek, R.N., Martens, M. and Temets, D., Co r r e l a t i o n of Instant Center Displacement and Inte r n a l Derangement of the Knee, Research Paper, unpublished, Vancouver General H o s p i t a l , Department of Orthopaedics, ! Vancouver, Canada. Noonan, R.C., and Cooke, C , A P i c t o r a l and Descriptive Taping Manual For A t h l e t i c Injury Management, going t o oress, 1977. O'Donoghue, D.H., S u r g i c a l Treatment of Fresh I n j u r i e s to the Major Ligaments of the Knee, Journal of Bone and J o i n t Surgery, V o l . 32-A, No. 2: 721-738, 1950. O'Donoghue, D.H., Reconstruction f o r Medial I n s t a b i l i t y of the Knee, Journal of Bone and J o i n t Surgery, V o l . 55-A: 941-55, 1973. Roser, L.A., M i l l e r , S.J and Clawson, D.K.,. E f f e c t s of Taping and Bracing on the Unstable Knee, Northwest Medicine: pp. 544-546, August, 1971, Rozin, R., Robin, G.C, Magora, A., Gonen, B. and S a l t i e l , J . , Investigation of Gait: I I I Analysis of Lower 106 Extremities Braced with a Standard Belav-Knee Appliance, Electromyography and Clinical Neurophysiology, Vol. 12, 433-440, 1972. Rouleaux, F., The Kinematics of Machinery; Outlines of A Theory of Machines, Translated and Edited by A.B. Kennedy, Macmillan and Company, London, England, 1876. Slocum, D.B., Larson, R.L. and James, S.L., Pes Anserinus Transplant: Impressions After a Decade of Experience, Journal of Sports Medicine, 2: 123-136, 1974. Slocum, D.B., Larson, R.L. and James, S.L., Late Reconstruction of Ligamentous Injuries of the Medial Coripartment of the Knee, Clinical Orthopaedics, 48: 23-55, 1975. Smidt, G.L., Biomechanical Analysis of Knee Flexion and Extension, Journal of Biomechanics, Vol. 6, pp. 79-92, 1973. Tipton, CM. and Karpovich, P.V., Clinical Electrogonicmetry, Journal of the Association for Physical and Mental Retardation, Vol. 18, No. 4, pp.90-109, July-August, . 1964. Tipton, CM. and Karpovich, P.V., Electrogonionetric Reoprds of Knee and Ankle Movements in Pathologic Gaits, Archives of Physical Medicine and Rehabilitation: 267-272, March, 1965. Wang, C.J., Rotatory Laxity of the Human Knee Joint, Journal of Bone and Joint Surgery, 56: 161-70, January, 1974. Wolf, B., The Effects of Flexion and Rotation on the Length Patterns of the Ligaments of the Knee, Biomechanics, Vol. 6: 587-596, 1973. APPENDIX A KNEE AXES OF ROTATION 108 APPENDIX A Knee Axes o f Rotation • INTERNAL-EXTERNAL ROTATION -AXIS FLEXION-! ROT, VARUS-VALGUS ROTATION AXIS i n t e r n a l r o t a t i o n external r o t a t i o n APPENDIX B SUBJECT CASE HISTORIES 110 APPENDIX B SUBJECT CASE HISTOPIES Subject B Weight: 70.4 Kg. Age: 24 years Occupation: Student Height: 140.8 arts. This young man received a twisting injury to the medial aspect of the left knee during the winter of 1970. During a slalom ski race, the tip of his left ski caught a pole and forcefully externally rotated. The left leg became abducted and pressure of the f a l l was directed on the medial aspect of the left knee. He remembers a pain on the medial aspect but got up and continued the race. Tenderness and swelling persisted and he consulted an orthopaedic surgeon. Clinical examination reveals a relatively lean and muscular young man of stated age with good quadriceps bulk and tone. There is demonstrable medial laxity in both left and right knees on aoDlicatlon of valgus stress. There is marked antero-posterior laxity with internal tibial rotation on examination with the anterior drawer test. Since the time of the i n i t i a l injury, the subject has maintained an active l i f e . He continues to ski, run, play handball and squash. He suffers repeated bouts of "knee collapse", pain and swelling i f he attemps to internally rotate with the hip on a flexed and weight- bearing knee. He appears to suffer from the "pivot-shift'' phenomenon. Tha subject has never been a candidate for surgery. Subject C Weight 104.5 Kg. Age: 29 years Occupation: Businessman Height: 162.8 cms. This man has had a history of knee injury from the age of 10 years. He reports collapsing on the knee of the right lea repeatedly while playing as a youngster. As he grew older, lie developed the quadriceps musculature and was able, with few problems, to actively engage in competitive rugby. For several years he continued, reaching national caliber and then retiring. After a vear's absence, he returned to the rugby scene suffering a "knee collaose" during a practice. Swelling resulted and, he consulted an orthopaedic surgeon. Clinical examination revealed a loose body in the medial aspect of the knee which was .confirmed by x-ray. Surgery was performed on the right knee in 1973 and the bone chip removed. He resumed his activity after rehabilitation playing rugby, handball and squash. After another lay-off of a year, he resumed competitive rugby. Another injury to the right knee resulted in swelling and pain on the medial aspect of the knee. The excess fluid was drained and the diagnosis of a strain of the medial collateral ligament was made. Another collapse of the knee resulted in arthroscopy in 1976 where incisions were made on the medial and lateral aspects of the right knee. No involvement of the menisci was found but the diagnosis of osteochondritis dessecans was made. The subject continues to be active, has lost some weight (10 kilos).and s t i l l suffers from knee collapse, pain and swelling. There is no ctemonstr able anterior or medial laxity on clinical exaiTunation. 112 APPENDIX C 2 x 2 CDLLAPBIBLE PARALLELOCIRAM CHAIN ELEGrROGQliaiETER 113 APPENDIX C 2 x 2 COLLAPSIBLE PAPALLELOGPAM CHAIN EIECTROGONIOME'rER Figure 37. Parallelogram chain linkages shewing (A) application on leg with brass brackets, metal wire thigh and calf frames and potentiometer cluster, (B) enlarged view of 2 x 2 narallelogram chain; arrows indicate longitudinal direction of chain scissoring allowing perpendicular rotations to pass through tlie chain unchanged while absorbing unwanted translations, and (C) enlarged section of parallelogram chain shewing hinge design. Parallelogram chain is constructed of polyurethane and is cast vacu-moulded. 114 APPENDIX D ELECTr«m«iaETRIC TESTING DATA SHEET 115 Page 1 APPENDIX D Electrogoniometric Testina Data Sheet* Patient: Test Date: Test Sequence Time Lines: A. Motions measured li. A c t i v i t i e s C. Aids used D. Chart sneed s t a r t end * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * A. Code Boxes f o r Motions: (shade i n boxes) 1. HIP KNEE ANKLE, HIP KNEE ANKLE L R L R L R DIR'N 2. L R L R L R DIR'N v/v VAL v/v VAL I/E EX/ROT I/E EX/ROT F/E FLEX F/E FLEX STANDING ZEROS h •• STANDS G ZEROS HIP KNEE ANKLE 4. HIP KNEE ANKLE L R L R L R DIR'N L R L R L R DIR'N V/V VAL V/V VAL J / E EX/ROT J/E EX/ROT F/E FLEX . F/E FLEX STANDING ZEROS h i STANDING ZEROS values are f o r F/E, I/E Rotation, V/V l e f t to r i g h t on oaqe * revised from an o r i g i n a l version by Steven Cousins, Canadian A r t h r i t i s and Rheumatism Society, Vancouver, B r i t i s h Columbia. Page 2 116 b. Code for A c t i v i t i e s : 1. Slow l e v e l walk 2. Comfortable l e v e l walk 3. Fast l e v e l walk 4. Slav l e v e l run 5. Comfortable l e v e l run C. Code for Aids: 1. None Braces - Knee Le f t Right B i l a t e r a l L.Varus L. Valgus R.Varus R.Valqus Varus Valgus Taylor Brace ( l a t e r a l iron) 2 3 4 5 6 7 Other Experimental Brace(s) 8 9 10 11 12 13 Le f t Knee Riqht Knee Int.Rot'n stop Ext.Rot'n stoo Int.Rot'n stoo Ext.Rot'n stoo Lennox-Hill 3raca 14 15 16 17 D. Code for Chart Speeds inm/min mm/sec 50 1 5 125 2 6 500 3 7 1250 4 8 117 Paae 3 Test Results Patient: Test Date: Code Boxes** Knee F/E Dynamic Range of Motion R L I/E/R Dynamic Range of Motion R L V/V Dynamic R Range of Motion L ** Use codes f o r A c t i v i t i e s and Aids from Page 1, eg., 1/1 = slow, l e v e l walk, no aids. 1/5 = slow,level walk, Taylor Brace, r i g h t knee, r i g h t valgus. 118 APPENDIX E INSTANT CENTER OF ROTATION CALCULATION APPENDIX E 119 Figure 38. Instant center of r o t a t i o n c a l c u l a t i o n shaving (B) successive p o s i t i o n s of points f o r p l o t t i n g center f o r knee motion from f l e x i o n t o extension; (E) c a l c u l a t i o n o f inst a n t center from perpendicular b i s e c t o r s of p o i n t s , and (M) i n s t a n t center of r o t a t i o n pathway on medial condyle of femur.

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