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Bracing for collateral ligamentinjuries of the knee
BRACING FOR COLLATERAL LIGAMENT INJURIES OF THE KNEE TIMOTHY B. SUTHERLAND, MD
Injury to the collateral ligaments of the knee is an extremely common occurrence in today's athletic population. Injuries to the knee can occur during both contact and noncontact sports. As a result, many attempts have been made to design braces for prophylaxis against injury, protection of the healing ligament, and stability of the ligamentously deficient knee. The efficacy and role of prophylactic braces have perhaps come under the most scrutiny. Biomechanically, testing has shown them to be of only questionable value in reducing the stress and load on the medial supporting structures of the knee. Clinically, with regard to their usefulness, there appear to be conflicting data as well. However, there does appear to be some support for their efficacy in reducing the incidence of injury on defensive players and all linemen in football. Physiologically, there are multiple studies that have proven brace wear to result in an adverse effect on both performance and energy use; this must also be considered before use. Injuries to the lateral side of the knee are far less common. Currently, there are no good studies that support brace wear for prophylaxis against injury to the lateral structures of the knee. Additionally, there is also no evidence to support the use of functional bracing in the chronically unstable knee. Current recommendations are for consideration of use of a prophylactic brace with a unilateral biaxial design for football players. Specifically, defensive position players and all linemen may gain the greatest benefit. The use of bilateral-hinge-design braces may be equally efficacious, but cost-prohibitive. The use of functional bracing for the chronically unstable knee is controversial with unsupported efficacy. Therefore, use for these indications should be considered on a case-by-case basis.
KEY WORDS: collateral ligament injury, prophylactic bracing, indications
Knee injuries are a v e r y c o m m o n occurrence in today's active society. In an attempt to control abnormal m o t i o n of the knee, m a n y knee bracing techniques and braces have been described. Knee braces have been categorized into three basic types b y the Sports Medicine Committee of the American A c a d e m y of Orthopaedic Surgeons. The three basic types are rehabilitation, functional, and prophylactic braces. 1 Rehabilitation braces are used primarily in the postinjury period to control range of m o t i o n and rotational forces acting on the knee. These can be used in both the postsurgical and in the n o n o p e r a t i v e treatment of collateral ligament injuries to the knee. Functional braces are designed to p r o v i d e stability to a knee that is otherwise unstable and are used primarily for anterior cruciate ligament-deficient knees. Prophylactic braces were designed to decrease the incidence and severity of knee injuries sustained d u r i n g athletic competition (Fig 1).
BRACING AND INJURIES TO THE MEDIAL COLLATERAL LIGAMENT The medial collateral ligament can be injured during both contact and noncontact sports and is the most con~'nonly injured ligament in the knee. 2 Partial injuries of the medial collateral ligament, grade I and grade II injuries, can occur with both noncontact rotational and abduction forces across the knee as well as with contact injuries. Complete, From the Desert Orthopaedic Center, Las Vegas, NV, and the University of California--Davis, Sacramento, CA. Address reprint requests to Timothy B. Sutherland, MD, Desert Orthopaedic Center, 3121 S Maryland Parkway No. 300, Las Vegas, NV 89109. Copyright © 1996 by W.B. Saunders Company
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or grade III, injuries are most often caused by a direct lateral blow to the knee during a collision or contact sport. 3 In an effort to prevent these c o m m o n injuries, prophylactic knee braces were designed for use d u r i n g contact sports to decrease the incidence and severity of injury with a direct lateral blow to the knee. Biomechanical and clinical studies have been u n d e r t a k e n to attempt to define the effectiveness of these prophylactic knee braces in preventing medial collateral ligament injury. In addition to delineating the protective effect of the brace, the overall effect of the brace on athletic performance m u s t also be considered.
BIOMECHANICAL STUDIES Various biomechanical studies have p r o v i d e d information regarding the effectiveness of prophylactic knee bracing. Baker et al 4 studied and c o m p a r e d the effectiveness of prophylactic and functional knee braces with regard to their ability to provide objective protection to the medial structures of the knee. Static abduction and external rotation forces were applied to cadaver knees in an attempt to recreate the forces seen d u r i n g athletic competitions. Functional braces were n o t e d to decrease the abduction angle, whereas prophylactic braces were n o t e d to have no significant protective effects. Additional studies b y Baker et al 5 loaded fresh cadaver knees at 0 ° and 30 ° of flexion with a lateral impact. Again, functional knee braces were noted to decrease abduction and rotational forces in the medial collateral ligament in both full extension and 30 ° flexion, whereas prophylactic braces had limited effect and were effective in full extension only. Paulos et al 6 u n d e r t o o k extensive biomechanical studies to evaluate the effectiveness of prophylactic braces using a Operative Techniques in Sports Medicine, Vol 4, No 3 (July), 1996: pp 202-208
B
Fig 1. (A) Commonly used unilateral prophylactic hinged-knee brace (DonJIoy, Carlsbad, CA). (B) Commonly used bilateral functional knee brace. (C) Common design of a rehabilitative knee brace with an adjustable hinge for motion control.
surrogate knee model. Several problems were noted with brace wear, including lateral joint clearance, center axis shift, and slippage of the braces in active sports use. Lateral joint clearance, the distance between the brace and lateral joint line, was noted to have a significant effect on brace perfoJ:mance. Contact of the brace and the lateral joint line during loading negated any prophylactic effect of the braces during use. Center axis shift, or the tendency of braces to alter the biomechanical center axis of the knee, BRACING FOR COLLATERAL LIGAMENT INJURIES
was also noted with possible alteration of stress in other ligamentous structures of the knee, including the anterior cruciate ligament. Brace slippage during use was noted to lead to alterations in function of both the brace and the knee. Of note, in addition to the adverse effects noted, no significant protection to the medial collateral ligament or medial supporting structures was documented in this study. France et al 7 studied brace effectiveness under lateral impact loading using a surrogate knee model and six 203
commercially available braces. Under ideal conditions, only one brace was noted to provide some protection to the medial collateral ligament. Three critical mechanical factors were identified that contributed to lateral brace function under dynamic lateral loads, absorption, distribution, and transmission of energy. Absorption is described as how the brace manages impact energy through deformation. Distribution describes brace design with regard to the distribution of impact forces across the brace and knee as a composite structure. Transmission refers to the energy imparted to the knee itself and was noted to be dependent on both brace material properties and appropriate design. The brace that performed best was noted to be constructed of a relatively stiff aluminum alloy. This design permitted deformation on initial impact and prevented jointline contact except under maximum loading conditions. It was noted that broad contact areas on the soft tissues of the thigh and calf helped to distribute loads away from the knee joint using a soft-tissue damping effect. Additional biomechanical studies by Paulos et al 8 noted that although medial collateral ligament protection was variable and of questionable significance with current knee brace designs, most braces did appear to offer increased protection to the anterior cruciate ligament under direct valgus loads. They concluded that lateral prophylactic knee bracing appeared to be beneficial in protecting both the medial collateral ligament and the anterior cruciate ligament against direct lateral blows to the knee. They again emphasized that brace hinge contact with the lateral jointline of the knee decreases effectiveness of the prophylactic brace. Their final recommendation noted that use of prophylactic knee braces was a reasonable option and should not be discouraged for contact sports. Erickson et al 9 studied the ability of prophylactic knee braces to reduce or limit both medial collateral and anterior cruciate ligament elongation under a dynamic load. After the cadaver knees were fitted with prophylactic knee braces, the legs were tested at 0 ° and 30 ° of knee flexion, both with and without an intact anterior cruciate ligament. The prophylactic knee brace was noted to significantly decrease the level of impact force at the point of impact, but this did not decrease anterior cruciate ligament elongation. All braces were noted to be more effective at reducing medial collateral ligament elongation with the knee at 30 ° of flexion than at 0 ° flexion. However, these findings were not significant. They concluded that the concept of prophylactic knee bracing was valuable and that additional research should be done on effective design of braces for protecting both the medial collateral ligament and anterior cruciate ligament. In summary, biomechanical testing of prophylactic knee braces has shown them to be only of questionable value in reducing the stress and load on the medial supporting structures of the knee. The use of surrogate knee models and cadaver knee models also has inherent problems, and extrapolation to the on-field situation of athletes is difficult.
CLINICAL STUDIES Clinical studies have also provided conflicting results and recommendations regarding prophylactic knee bracing and medial collateral ligament injury. Various studies have 204
shown no change in injury rate and severity, and increased injuries and decreased injuries with the use of prophylactic knee braces. Difficulty in comparing studies is caused by the generally retrospective nature of these studies and multiple uncontrolled factors, including level of competition, size of athlete, shoe surface interface, and type and duration of brace wear. Teitz et al 1° in a large, multicenter study, collected data on National Collegiate Athletic Association (NCAA) Division I athletes over a 2-year period. They noted both in the overall group and in subsets by position that players who wore braces actually had an incidence of injury that was equal to or greater than that of the players who were unbraced. These included injuries to the medial collateral ligament, the anterior cruciate ligament, and the meniscus. There was no difference in the severity of injuries between the braced and unbraced players in the 2 years of the study. They concluded that the increased injury rate in braced players may have been the result of decrease agility caused by the braces, carelessness of players who believed that they were protected, or preloading of the medial collateral ligament in players who had genu varum. They concluded that these preventative braces were not preventative and indeed were potentially harmful to the collegiate athlete. Grace et a111 reviewed the effect of prophylactic knee bracing in high school football players studied over two complete seasons. Both single-hinge braces and doublehinge braces were evaluated, and these athletes were compared with unbraced athletes. They noted a statistically significant increase in knee injuries in the group that wore single-hinge braces as compared with the nonbrace group, and they also noted a trend toward an increased number of injuries in the double-hinged brace as compared with the unbraced group, although this was not statistically significant. Of note, they noted a significant dramatic increase in the number of injuries of the ankle and foot in athletes who wore these prophylactic knee braces. These included severe ankle sprains; fracture of the foot, distal fibula, and proximal fibula; and rupture of the Achilles tendon. They concluded that the biomechanical stresses on the lower extremity were altered by the prophylactic knee braces, thus shifting injury force to an adjacent anatomical area. Retrospective studies by Hewson et aP 2 and Rovere et a113of university athletes found no significant difference in injury rate or severity with use of prophylactic knee bracing. Many of these studies did note the difficulty in extrapolating data from a certain level of competition, ie, high school versus collegiate versus professional to the general athletic population. Epidemiological studies by Requa and Garrett ~4of prophylactic knee brace use in high school and college athletes noted no significant change in the incidence or severity of injuries with the use of prophylactic knee bracing. Sitler et al ~s performed a prospective randomized study of prophylactic knee bracing at the United States Military Academy in West Point, N e w York. This study controlled the athletic environment, and the athletic shoe, playing surface, athlete exposure, knee injury history, and brace assignment were either statistically or experimentally controlled. Participants were cadets in an intermural tackle football program over two seasons. The use of prophylactic TIMOTHY B. SUTHERLAND
knee braces was noted in this study to significantly reduce the frequency of knee injuries both in the total number of subjects injured and in the total number of medial collateral ligament injuries incurred. This decreased incidence of injury was noted to be position-specific. Defensive players who wore the prophylactic knee braces were noted to have statistically decreased knee injury as compared with players who were unbraced. This difference in injury incidence was not noted to be present in the offensive players when brace 'wearers were compared with nonbrace wearers. Of interest, the severity of both injuries to the medial collateral ligament and anterior cruciate ligament were not significantly changed with the use of prophylactic knee braces. Because Grace et a111 had noted a difference in injury rates with varying braces, the brace use was controlled and a double-hinged single upright lateral brace was applied via a no-slip strap and neoprene thigh and calf straps. Brace slippage was noted to occur, and this was controlled with application of adhesive tape. They did note that their average athlete's size was approximately 71 inches and 173 pounds. They concluded that the use of prophylactic knee braces was effective in reducing knee injuries in their population, but that it may well be dependent on the level of play at which the braces are used as well as the type of brace used. On review of their data, they found no significant increase in the incidence of ankle and foot injuries when a prophylactic knee brace was worn. Albright et aP 6 studied the effectiveness of preventative braces in the NCAA Division I college football players. Player position, situation of game versus practice, and daily brace wear were recorded. When the factors of position, string, and session were considered, there was a consistent but not statistically significant tendency for the athletes wearing preventative knee braces to have a lower incidence of injury as compared with the unbraced athlete. For athletes in the offensive and defensive line, linebackers and tight ends, there was a consistent trend toward a decreased incidence in injury in both practices and games. Of interest, braced players in the skill positions were noted to have a higher injury rate, at least during actual game situations. They concluded that their study suggested that knee braces were efficient in decreasing medial collateral ligament sprains but agreed that further study was necessary. In summary, clinical studies provide conflicting data regarding the effectiveness of prophylactic braces in decreasing the incidence and severity of medial collateral ligament injuries. This disagreement underlies the need for additional prospective, randomized studies on the clinical use of prophylactic braces in athletes of all ages and skill levels.
PHYSIOLOGICAL EFFECTS OF BRACING In addition to the conflicting results regarding prophylactic knee bracing found in both biomechanical and clinical studies, the use of braces has also been found to have adverse effects on the athlete's performance and energy use.
Highgenboten et aP 7 studied the effect of commercially available braces on treadmill running. They noted increases in oxygen consumption, heart rate, and ventilation, BRACING FOR COLLATERAL LIGAMENT INJURIES
and this increase in energy expenditure was thought to be secondary to the weight of the brace itself. Styf et aUg studied muscle compartment pressures with the use of restraining straps and found increased pressures that were thought to lead to premature fatigue of the braced limb. Zetterlund et aU9 also studied the effects of brace wearing using treadmill testing. Brace use was noted to increase oxygen consumption and heart rate and to decrease stride length. Houston and Goemans 2° showed that knee bracing decreased strength on isokinetic testing, decreased velocity during stair run, and increased blood lactate levels during a 15-min bicycle ergometer ride. These effects on performance are significant and must be considered before recommending routine brace wear for contact athletes.
BRACING AND INJURIES TO THE LATERAL COLLATERAL LIGAMENT Injuries to the lateral structures of the knee are much less common than injuries involving the medial structures of the knee and the cruciate ligaments. 22,23These injuries may be either isolated injuries to the lateral collateral ligament, or more commonly, combined injuries to the lateral collateral ligament with the posterolateral structures, posterior cruciate ligament, or anterior cruciate ligament. Biomechanical studies have shown the importance of the lateral collateral ligament proper, posterolateral capsule, other posterolateral structures, and cruciate ligaments in the prevention of instability to varus stress. 24,25Because of the fact that these structures are commonly injured in combination, a physical examination must be performed carefully to completely evaluate the knee in full extension, 30 ° flexion, and 90 ° flexion. Examination must evaluate the integrity of the lateral collateral ligament proper, the posterolateral structures, the anterior and posterior cruciate ligaments. Additional imaging structures such as a magnetic resonance imaging scan may be necessary to completely delineate injuries to these structures. Although the use of prophylactic bracing for the prevention of medial structures has been well studied, there are no good studies evaluating the use of prophylactic braces for the prevention of injuries to the lateral structures of the knee. Therefore, I do not recommend that prophylactic braces be used specifically for this purpose. The use of rehabilitation braces after the surgical repair of acute or chronic straight lateral or posterolateral instability has been well described. 23,26 Various regimens for postoperative use have been described, and generally a doublehinged knee brace is used to gradually increase the range of motion in the postoperative period. Long-term bracing postoperatively is generally not recommended and has not been shown to have any significant effect in preventing reinjury. Rehabilitation braces may also be used after injury to the lateral structures that result in only mild instability to varus stress. These braces are thought to allow the lateral and posterolateral structures to heal and are generally combined with a supervised rehabilitation program. In this setting, great care must be taken to ensure that there is no significant laxity and ~ a t no significant damage to associated posterolateral structures of the cruci205
ate ligaments has taken place. No definitive evidence exists showing that functional bracing, when used in the chronically unstable knee, is effective. Current treatment usually involves surgical reconstruction if symptomatic posterolateral or straight lateral instability is present. Rehabilitation braces are used postoperatively in this situation. In summary, much less is known about the effect of prophylactic or functional bracing in the use of injuries to the lateral structures of the knee. Rehabilitative bracing is effective and has been used in both the postoperative and the nonoperative treatment of mild injuries.
CONCLUSION Prophylactic bracing for medial collateral ligament injuries remains a controversial topic. Biomechanical studies have been performed to attempt to define the exact role and degree of protection provided by these prophylactic braces. Results to date have been inconclusive, and further study is required to delineate the exact role of these braces in preventing the incidence and severity of injuries. Clinical studies are similarly inconclusive. Studies have shown an increased rate of injury, a decreased rate of injury, and no change in injury rate. Difficulties in clinical studies include varying levels of competition with athletes of varying sizes, and the presence of uncontrolled variables in terms of previous injuries, shoe surface interaction, and daily brace wear. To further add to the factors that should be considered before recommending brace use, braces have
been shown to have a detrimental effect on physiological perimeters important in athletic competition. My current recommendations are to discuss the potential advantages and disadvantages of prophylactic knee bracing with both the athletes and the coaches of teams. I believe some benefit may be gained in both the high school and collegiate athlete for certain player positions. Using recommendations suggested by the Sitler et aP 5 study on West Point Intramural athletes, I recommend that all things being equal, defensive players on high school teams consider prophylactic knee bracing. Recommendations for collegiate players are based on the study of Allbright et al, 16 and currently I recommend bracing of offensive and defensive lineman, linebackers, and tight ends. Of the commercially available braces, I prefer a unilateral biaxial prophylactic brace because there is some evidence that these provide the greatest resistance to lateral impact loads. Care must be taken with the use of these braces to minimize the slippage of the brace with adhesive tape and also to ensure appropriate fitting to minimize lateral joint contact. The most commonly used braces in m y practice include the Don Joy protective knee guard (DonJoy, Carlsbad, CA) (Fig 2) and the Omni Anderson Knee Stabler (Omni Scientific, Inc, Concord, CA) (Fig 3). Many athletes have a pre-established brace preference for either the Don Joy or Omni brace. If no preference is noted, the braces are tried on the lower extremity to find the optimal fit and comfort for the athlete. Appropriate placement of the brace is carefully reviewed with the
Fig 2. DonJoy unilateral biaxial hinged-knee brace (DonJoy, Carlsbad, CA).
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TIMOTHY B. SUTHERLAND
Fig 3. Omni unilateral biaxial hinge-knee stabilizer brace (Omni Scientific, Inc, Concord, CA). athlete a n d the trainer a n d periodically inspected in b o t h practice a n d g a m e situations. The m o s t c o m m o n l y n o t e d p r o b l e m s in athletes include slippage a n d lateral joint line contact.
reconstructed knee or knee w i t h c o m b i n e d l i g a m e n t o u s injury. Additional insight m a y be obtained b y reviewing previous articles discussing rehabilitation a n d t r e a t m e n t of the isolated a n d c o m b i n e d m e d i a l collateral l i g a m e n t injury.
Rehabilitative Braces Rehabilitative braces are quite useful in the t r e a t m e n t of b o t h o p e r a t i v e l y a n d n o n o p e r a t i v e l y treated injuries of the m e d i a l collateral ligament. Various protocols involving the u s e of h i n g e d braces h a v e b e e n described for the t r e a t m e n t of all degrees of m e d i a l collateral l i g a m e n t injuries. T h e s e protocols are b e y o n d articles on t r e a t m e n t a n d rehabilitation of collateral l i g a m e n t injuries of the knee. Biomechanical studies of c o m m e r c i a l rehabilitative braces h a v e f o u n d that m o s t braces decrease b o t h translation a n d rotation c o m p a r e d w i t h the contracted limb. 21 These braces are, however, limited in n o r m a l w e i g h t - b e a r i n g conditions a n d are a p p r o p r i a t e l y u s e d for rehabilitation only.
Functional Braces Functional braces h a v e b e e n designed to a u g m e n t the stabi!Lity of unstable knees. T h e y are m o s t c o m m o n l y u s e d in the anterior-cruciate-deficient a n d anterior-cruciatereconstructed knee. Functional braces h a v e b e e n s h o w n to d e c r e a s e the load on the m e d i a l collateral l i g a m e n t 4,5 a n d m a y be useful in certain situations for protection w h e n the athlete returns to competition. The significantly higher e x p e n s e o f t h e s e braces often restricts their use to the BRACING FOR COLLATERAL LIGAMENT INJURIES
REFERENCES 1. Drez D, Jr (ed): Knee Braces: Seminar Report. Chicago, IL, American Academy of Orthopaedic Surgeons, 1985 2. Fetto JF, Marshall JL: Medial collateral ligament injuries of the knee: A rationale for treatment. Clin Orthop 132:206-217, 1978 3. Feagin JA: The Crucial Ligaments: Diagnostic and Treatment of Ligamentous Injuries About the Knee. New York, NY, Churchill Livingstone, 1988 4. BakerBE, Van Hanswyk E, Bogosian S, et al: A biomechanical study of the static stabilizing effect on knee braces on medial stability. Am J Sports Med 15:566-570, 1987 5. Baker BE, Vanttanswyk E, Bogosian S, et al: The effect of knee braces on lateral impact loading of the knee. Am J Sports Med 11:345-348, 1983 6. Paulos LE, France EP, Rosenberg TD, et ah The biomechanics of lateral knee bracing: I. Response of the valgus restraints to loading. Am J Sports Med 15:419-429, 1987 7. France EP, Paulos LE, lagaraman G: The biomechanics of lateral knee bracing: IL Impact response of the braced knee. Am J Sports Med 15:430-438, 1987 8. Paulos LE, Cawley PW, France EP: Impact biomechanics of lateral knee bracing: The anterior cruciate ligament. Am J Sports Med 19:337-342,1991 9. Erickson AR, Tasuda K, Beynnon B, et al: An in vitro dynamic evaluation of prophylactic knee braces during lateral impact loading. Am J Sports Med 21:26-35, 1993 207
10. Teitz CC, Hermanson BK, Kronmal RA, et al: Evaluation of the use of braces to prevent injury to the knee in collegiate football players. J Bone Joint Surg 69A:2-9,1987 11. Grace TG, Skipper BJ, Newberry JC, et al: Prophylactic knee braces and injury to the lower extremity. J Bone Joint Surg 70A:422-427, 1988 12. Hewson GR, Mendini RA, Wong JB: Prophylactic knee bracing in college football. Am J Sports Med 14:262-266, 1986 13. Rovere GD, Haupt HA, Yates CS: Prophylactic knee bracing in college football. Am J Sports Med 15:111-116,1987 14. Requa RK, Garrett JG: Clinical significant and evaluation of prophylactic knee brace studies in football. Clin Sports Med 9:853-869, 1990 15. Sitler S, Ryan J, Hopkinson W, et al: The efficiency of a prophylactic knee brace to reduce knee injuries in football: A prospective randomized study at West Point. Am J Sports Med 18:310-315,1990 16. Albright JP, Powell JW, Smith W, et ah Medial collateral ligament knee sprains in college football: Effectiveness of preventative braces. Am J Sports Med 22:12-18, 1994 17. Highgenboten CL, Jackson A, Meske N, et al: The effects of knee brace wear on perceptive and metabolic variables during horizontal treadmill runners. Am J Sports Med 19:639-643,1991 18. Styf JR, Nakitostie M, Gershuri D: Functional knee braces increase intramuscular pressures in the anterior compartment of the leg. Am J Sports Med 20:46-49, 1992
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19. Zetterlund AE, Serfass RC, Hunter RE: The effect of wearing the complex Lenox Hill Derotation Brace on energy expenditure during horizontal treadmill running at 161 m/rain. Am J Sports Med 14:73-76, 1986 20. Houston ME, Goemans PH: Leg muscle performance of athletes with and without knee support braces. Arch Phys Med Rehabi163:431-432, 1982 21. Cawley PW, France EP, Paulos LE: Comparison of rehabilitative knee braces: A biomechanical investigation. Am J Sports Med 17:141-146, 1989 22. Hughston JC, Andrews JR, Cross MJ, et al: Classification of knee ligament instabilities, Part II. The lateral compartment. J Bone Joint Surg 58A:173-179, 1976 23. Baker CL, Norwood LA, Hughston JC: Acute posterolateral rotatory instability of the knee. J Bone Joint Surg 65A:614-618, 1983 24. Grood ES, Noyes FR, Butler DL: Ligamentous and capsular restraints preventing medial and lateral laxity in intact human cadaver knees. J Bone Joint Surg 63A:1257-1269,1981 25. Gollehan DL, Torzilli PA, Warren RF: The role of the posterolateral and cruciate ligament instability of the human knee. J Bone Joint Surg 69A:233-242,1987 26. DeLee JD, Riley MB, Rockwood CA: Acute straight lateral instability of the knee. Am J Sports Med 11:404-411, 1983
TIMOTHY B. SUTHERLAND
Injury to the collateral ligaments of the knee is an extremely common occurrence in today's athletic population. Injuries to the knee can occur during both contact and noncontact sports. As a result, many attempts have been made to design braces for prophylaxis against injury, protection of the healing ligament, and stability of the ligamentously deficient knee. The efficacy and role of prophylactic braces have perhaps come under the most scrutiny. Biomechanically, testing has shown them to be of only questionable value in reducing the stress and load on the medial supporting structures of the knee. Clinically, with regard to their usefulness, there appear to be conflicting data as well. However, there does appear to be some support for their efficacy in reducing the incidence of injury on defensive players and all linemen in football. Physiologically, there are multiple studies that have proven brace wear to result in an adverse effect on both performance and energy use; this must also be considered before use. Injuries to the lateral side of the knee are far less common. Currently, there are no good studies that support brace wear for prophylaxis against injury to the lateral structures of the knee. Additionally, there is also no evidence to support the use of functional bracing in the chronically unstable knee. Current recommendations are for consideration of use of a prophylactic brace with a unilateral biaxial design for football players. Specifically, defensive position players and all linemen may gain the greatest benefit. The use of bilateral-hinge-design braces may be equally efficacious, but cost-prohibitive. The use of functional bracing for the chronically unstable knee is controversial with unsupported efficacy. Therefore, use for these indications should be considered on a case-by-case basis.
KEY WORDS: collateral ligament injury, prophylactic bracing, indications
Knee injuries are a v e r y c o m m o n occurrence in today's active society. In an attempt to control abnormal m o t i o n of the knee, m a n y knee bracing techniques and braces have been described. Knee braces have been categorized into three basic types b y the Sports Medicine Committee of the American A c a d e m y of Orthopaedic Surgeons. The three basic types are rehabilitation, functional, and prophylactic braces. 1 Rehabilitation braces are used primarily in the postinjury period to control range of m o t i o n and rotational forces acting on the knee. These can be used in both the postsurgical and in the n o n o p e r a t i v e treatment of collateral ligament injuries to the knee. Functional braces are designed to p r o v i d e stability to a knee that is otherwise unstable and are used primarily for anterior cruciate ligament-deficient knees. Prophylactic braces were designed to decrease the incidence and severity of knee injuries sustained d u r i n g athletic competition (Fig 1).
BRACING AND INJURIES TO THE MEDIAL COLLATERAL LIGAMENT The medial collateral ligament can be injured during both contact and noncontact sports and is the most con~'nonly injured ligament in the knee. 2 Partial injuries of the medial collateral ligament, grade I and grade II injuries, can occur with both noncontact rotational and abduction forces across the knee as well as with contact injuries. Complete, From the Desert Orthopaedic Center, Las Vegas, NV, and the University of California--Davis, Sacramento, CA. Address reprint requests to Timothy B. Sutherland, MD, Desert Orthopaedic Center, 3121 S Maryland Parkway No. 300, Las Vegas, NV 89109. Copyright © 1996 by W.B. Saunders Company
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or grade III, injuries are most often caused by a direct lateral blow to the knee during a collision or contact sport. 3 In an effort to prevent these c o m m o n injuries, prophylactic knee braces were designed for use d u r i n g contact sports to decrease the incidence and severity of injury with a direct lateral blow to the knee. Biomechanical and clinical studies have been u n d e r t a k e n to attempt to define the effectiveness of these prophylactic knee braces in preventing medial collateral ligament injury. In addition to delineating the protective effect of the brace, the overall effect of the brace on athletic performance m u s t also be considered.
BIOMECHANICAL STUDIES Various biomechanical studies have p r o v i d e d information regarding the effectiveness of prophylactic knee bracing. Baker et al 4 studied and c o m p a r e d the effectiveness of prophylactic and functional knee braces with regard to their ability to provide objective protection to the medial structures of the knee. Static abduction and external rotation forces were applied to cadaver knees in an attempt to recreate the forces seen d u r i n g athletic competitions. Functional braces were n o t e d to decrease the abduction angle, whereas prophylactic braces were n o t e d to have no significant protective effects. Additional studies b y Baker et al 5 loaded fresh cadaver knees at 0 ° and 30 ° of flexion with a lateral impact. Again, functional knee braces were noted to decrease abduction and rotational forces in the medial collateral ligament in both full extension and 30 ° flexion, whereas prophylactic braces had limited effect and were effective in full extension only. Paulos et al 6 u n d e r t o o k extensive biomechanical studies to evaluate the effectiveness of prophylactic braces using a Operative Techniques in Sports Medicine, Vol 4, No 3 (July), 1996: pp 202-208
B
Fig 1. (A) Commonly used unilateral prophylactic hinged-knee brace (DonJIoy, Carlsbad, CA). (B) Commonly used bilateral functional knee brace. (C) Common design of a rehabilitative knee brace with an adjustable hinge for motion control.
surrogate knee model. Several problems were noted with brace wear, including lateral joint clearance, center axis shift, and slippage of the braces in active sports use. Lateral joint clearance, the distance between the brace and lateral joint line, was noted to have a significant effect on brace perfoJ:mance. Contact of the brace and the lateral joint line during loading negated any prophylactic effect of the braces during use. Center axis shift, or the tendency of braces to alter the biomechanical center axis of the knee, BRACING FOR COLLATERAL LIGAMENT INJURIES
was also noted with possible alteration of stress in other ligamentous structures of the knee, including the anterior cruciate ligament. Brace slippage during use was noted to lead to alterations in function of both the brace and the knee. Of note, in addition to the adverse effects noted, no significant protection to the medial collateral ligament or medial supporting structures was documented in this study. France et al 7 studied brace effectiveness under lateral impact loading using a surrogate knee model and six 203
commercially available braces. Under ideal conditions, only one brace was noted to provide some protection to the medial collateral ligament. Three critical mechanical factors were identified that contributed to lateral brace function under dynamic lateral loads, absorption, distribution, and transmission of energy. Absorption is described as how the brace manages impact energy through deformation. Distribution describes brace design with regard to the distribution of impact forces across the brace and knee as a composite structure. Transmission refers to the energy imparted to the knee itself and was noted to be dependent on both brace material properties and appropriate design. The brace that performed best was noted to be constructed of a relatively stiff aluminum alloy. This design permitted deformation on initial impact and prevented jointline contact except under maximum loading conditions. It was noted that broad contact areas on the soft tissues of the thigh and calf helped to distribute loads away from the knee joint using a soft-tissue damping effect. Additional biomechanical studies by Paulos et al 8 noted that although medial collateral ligament protection was variable and of questionable significance with current knee brace designs, most braces did appear to offer increased protection to the anterior cruciate ligament under direct valgus loads. They concluded that lateral prophylactic knee bracing appeared to be beneficial in protecting both the medial collateral ligament and the anterior cruciate ligament against direct lateral blows to the knee. They again emphasized that brace hinge contact with the lateral jointline of the knee decreases effectiveness of the prophylactic brace. Their final recommendation noted that use of prophylactic knee braces was a reasonable option and should not be discouraged for contact sports. Erickson et al 9 studied the ability of prophylactic knee braces to reduce or limit both medial collateral and anterior cruciate ligament elongation under a dynamic load. After the cadaver knees were fitted with prophylactic knee braces, the legs were tested at 0 ° and 30 ° of knee flexion, both with and without an intact anterior cruciate ligament. The prophylactic knee brace was noted to significantly decrease the level of impact force at the point of impact, but this did not decrease anterior cruciate ligament elongation. All braces were noted to be more effective at reducing medial collateral ligament elongation with the knee at 30 ° of flexion than at 0 ° flexion. However, these findings were not significant. They concluded that the concept of prophylactic knee bracing was valuable and that additional research should be done on effective design of braces for protecting both the medial collateral ligament and anterior cruciate ligament. In summary, biomechanical testing of prophylactic knee braces has shown them to be only of questionable value in reducing the stress and load on the medial supporting structures of the knee. The use of surrogate knee models and cadaver knee models also has inherent problems, and extrapolation to the on-field situation of athletes is difficult.
CLINICAL STUDIES Clinical studies have also provided conflicting results and recommendations regarding prophylactic knee bracing and medial collateral ligament injury. Various studies have 204
shown no change in injury rate and severity, and increased injuries and decreased injuries with the use of prophylactic knee braces. Difficulty in comparing studies is caused by the generally retrospective nature of these studies and multiple uncontrolled factors, including level of competition, size of athlete, shoe surface interface, and type and duration of brace wear. Teitz et al 1° in a large, multicenter study, collected data on National Collegiate Athletic Association (NCAA) Division I athletes over a 2-year period. They noted both in the overall group and in subsets by position that players who wore braces actually had an incidence of injury that was equal to or greater than that of the players who were unbraced. These included injuries to the medial collateral ligament, the anterior cruciate ligament, and the meniscus. There was no difference in the severity of injuries between the braced and unbraced players in the 2 years of the study. They concluded that the increased injury rate in braced players may have been the result of decrease agility caused by the braces, carelessness of players who believed that they were protected, or preloading of the medial collateral ligament in players who had genu varum. They concluded that these preventative braces were not preventative and indeed were potentially harmful to the collegiate athlete. Grace et a111 reviewed the effect of prophylactic knee bracing in high school football players studied over two complete seasons. Both single-hinge braces and doublehinge braces were evaluated, and these athletes were compared with unbraced athletes. They noted a statistically significant increase in knee injuries in the group that wore single-hinge braces as compared with the nonbrace group, and they also noted a trend toward an increased number of injuries in the double-hinged brace as compared with the unbraced group, although this was not statistically significant. Of note, they noted a significant dramatic increase in the number of injuries of the ankle and foot in athletes who wore these prophylactic knee braces. These included severe ankle sprains; fracture of the foot, distal fibula, and proximal fibula; and rupture of the Achilles tendon. They concluded that the biomechanical stresses on the lower extremity were altered by the prophylactic knee braces, thus shifting injury force to an adjacent anatomical area. Retrospective studies by Hewson et aP 2 and Rovere et a113of university athletes found no significant difference in injury rate or severity with use of prophylactic knee bracing. Many of these studies did note the difficulty in extrapolating data from a certain level of competition, ie, high school versus collegiate versus professional to the general athletic population. Epidemiological studies by Requa and Garrett ~4of prophylactic knee brace use in high school and college athletes noted no significant change in the incidence or severity of injuries with the use of prophylactic knee bracing. Sitler et al ~s performed a prospective randomized study of prophylactic knee bracing at the United States Military Academy in West Point, N e w York. This study controlled the athletic environment, and the athletic shoe, playing surface, athlete exposure, knee injury history, and brace assignment were either statistically or experimentally controlled. Participants were cadets in an intermural tackle football program over two seasons. The use of prophylactic TIMOTHY B. SUTHERLAND
knee braces was noted in this study to significantly reduce the frequency of knee injuries both in the total number of subjects injured and in the total number of medial collateral ligament injuries incurred. This decreased incidence of injury was noted to be position-specific. Defensive players who wore the prophylactic knee braces were noted to have statistically decreased knee injury as compared with players who were unbraced. This difference in injury incidence was not noted to be present in the offensive players when brace 'wearers were compared with nonbrace wearers. Of interest, the severity of both injuries to the medial collateral ligament and anterior cruciate ligament were not significantly changed with the use of prophylactic knee braces. Because Grace et a111 had noted a difference in injury rates with varying braces, the brace use was controlled and a double-hinged single upright lateral brace was applied via a no-slip strap and neoprene thigh and calf straps. Brace slippage was noted to occur, and this was controlled with application of adhesive tape. They did note that their average athlete's size was approximately 71 inches and 173 pounds. They concluded that the use of prophylactic knee braces was effective in reducing knee injuries in their population, but that it may well be dependent on the level of play at which the braces are used as well as the type of brace used. On review of their data, they found no significant increase in the incidence of ankle and foot injuries when a prophylactic knee brace was worn. Albright et aP 6 studied the effectiveness of preventative braces in the NCAA Division I college football players. Player position, situation of game versus practice, and daily brace wear were recorded. When the factors of position, string, and session were considered, there was a consistent but not statistically significant tendency for the athletes wearing preventative knee braces to have a lower incidence of injury as compared with the unbraced athlete. For athletes in the offensive and defensive line, linebackers and tight ends, there was a consistent trend toward a decreased incidence in injury in both practices and games. Of interest, braced players in the skill positions were noted to have a higher injury rate, at least during actual game situations. They concluded that their study suggested that knee braces were efficient in decreasing medial collateral ligament sprains but agreed that further study was necessary. In summary, clinical studies provide conflicting data regarding the effectiveness of prophylactic braces in decreasing the incidence and severity of medial collateral ligament injuries. This disagreement underlies the need for additional prospective, randomized studies on the clinical use of prophylactic braces in athletes of all ages and skill levels.
PHYSIOLOGICAL EFFECTS OF BRACING In addition to the conflicting results regarding prophylactic knee bracing found in both biomechanical and clinical studies, the use of braces has also been found to have adverse effects on the athlete's performance and energy use.
Highgenboten et aP 7 studied the effect of commercially available braces on treadmill running. They noted increases in oxygen consumption, heart rate, and ventilation, BRACING FOR COLLATERAL LIGAMENT INJURIES
and this increase in energy expenditure was thought to be secondary to the weight of the brace itself. Styf et aUg studied muscle compartment pressures with the use of restraining straps and found increased pressures that were thought to lead to premature fatigue of the braced limb. Zetterlund et aU9 also studied the effects of brace wearing using treadmill testing. Brace use was noted to increase oxygen consumption and heart rate and to decrease stride length. Houston and Goemans 2° showed that knee bracing decreased strength on isokinetic testing, decreased velocity during stair run, and increased blood lactate levels during a 15-min bicycle ergometer ride. These effects on performance are significant and must be considered before recommending routine brace wear for contact athletes.
BRACING AND INJURIES TO THE LATERAL COLLATERAL LIGAMENT Injuries to the lateral structures of the knee are much less common than injuries involving the medial structures of the knee and the cruciate ligaments. 22,23These injuries may be either isolated injuries to the lateral collateral ligament, or more commonly, combined injuries to the lateral collateral ligament with the posterolateral structures, posterior cruciate ligament, or anterior cruciate ligament. Biomechanical studies have shown the importance of the lateral collateral ligament proper, posterolateral capsule, other posterolateral structures, and cruciate ligaments in the prevention of instability to varus stress. 24,25Because of the fact that these structures are commonly injured in combination, a physical examination must be performed carefully to completely evaluate the knee in full extension, 30 ° flexion, and 90 ° flexion. Examination must evaluate the integrity of the lateral collateral ligament proper, the posterolateral structures, the anterior and posterior cruciate ligaments. Additional imaging structures such as a magnetic resonance imaging scan may be necessary to completely delineate injuries to these structures. Although the use of prophylactic bracing for the prevention of medial structures has been well studied, there are no good studies evaluating the use of prophylactic braces for the prevention of injuries to the lateral structures of the knee. Therefore, I do not recommend that prophylactic braces be used specifically for this purpose. The use of rehabilitation braces after the surgical repair of acute or chronic straight lateral or posterolateral instability has been well described. 23,26 Various regimens for postoperative use have been described, and generally a doublehinged knee brace is used to gradually increase the range of motion in the postoperative period. Long-term bracing postoperatively is generally not recommended and has not been shown to have any significant effect in preventing reinjury. Rehabilitation braces may also be used after injury to the lateral structures that result in only mild instability to varus stress. These braces are thought to allow the lateral and posterolateral structures to heal and are generally combined with a supervised rehabilitation program. In this setting, great care must be taken to ensure that there is no significant laxity and ~ a t no significant damage to associated posterolateral structures of the cruci205
ate ligaments has taken place. No definitive evidence exists showing that functional bracing, when used in the chronically unstable knee, is effective. Current treatment usually involves surgical reconstruction if symptomatic posterolateral or straight lateral instability is present. Rehabilitation braces are used postoperatively in this situation. In summary, much less is known about the effect of prophylactic or functional bracing in the use of injuries to the lateral structures of the knee. Rehabilitative bracing is effective and has been used in both the postoperative and the nonoperative treatment of mild injuries.
CONCLUSION Prophylactic bracing for medial collateral ligament injuries remains a controversial topic. Biomechanical studies have been performed to attempt to define the exact role and degree of protection provided by these prophylactic braces. Results to date have been inconclusive, and further study is required to delineate the exact role of these braces in preventing the incidence and severity of injuries. Clinical studies are similarly inconclusive. Studies have shown an increased rate of injury, a decreased rate of injury, and no change in injury rate. Difficulties in clinical studies include varying levels of competition with athletes of varying sizes, and the presence of uncontrolled variables in terms of previous injuries, shoe surface interaction, and daily brace wear. To further add to the factors that should be considered before recommending brace use, braces have
been shown to have a detrimental effect on physiological perimeters important in athletic competition. My current recommendations are to discuss the potential advantages and disadvantages of prophylactic knee bracing with both the athletes and the coaches of teams. I believe some benefit may be gained in both the high school and collegiate athlete for certain player positions. Using recommendations suggested by the Sitler et aP 5 study on West Point Intramural athletes, I recommend that all things being equal, defensive players on high school teams consider prophylactic knee bracing. Recommendations for collegiate players are based on the study of Allbright et al, 16 and currently I recommend bracing of offensive and defensive lineman, linebackers, and tight ends. Of the commercially available braces, I prefer a unilateral biaxial prophylactic brace because there is some evidence that these provide the greatest resistance to lateral impact loads. Care must be taken with the use of these braces to minimize the slippage of the brace with adhesive tape and also to ensure appropriate fitting to minimize lateral joint contact. The most commonly used braces in m y practice include the Don Joy protective knee guard (DonJoy, Carlsbad, CA) (Fig 2) and the Omni Anderson Knee Stabler (Omni Scientific, Inc, Concord, CA) (Fig 3). Many athletes have a pre-established brace preference for either the Don Joy or Omni brace. If no preference is noted, the braces are tried on the lower extremity to find the optimal fit and comfort for the athlete. Appropriate placement of the brace is carefully reviewed with the
Fig 2. DonJoy unilateral biaxial hinged-knee brace (DonJoy, Carlsbad, CA).
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TIMOTHY B. SUTHERLAND
Fig 3. Omni unilateral biaxial hinge-knee stabilizer brace (Omni Scientific, Inc, Concord, CA). athlete a n d the trainer a n d periodically inspected in b o t h practice a n d g a m e situations. The m o s t c o m m o n l y n o t e d p r o b l e m s in athletes include slippage a n d lateral joint line contact.
reconstructed knee or knee w i t h c o m b i n e d l i g a m e n t o u s injury. Additional insight m a y be obtained b y reviewing previous articles discussing rehabilitation a n d t r e a t m e n t of the isolated a n d c o m b i n e d m e d i a l collateral l i g a m e n t injury.
Rehabilitative Braces Rehabilitative braces are quite useful in the t r e a t m e n t of b o t h o p e r a t i v e l y a n d n o n o p e r a t i v e l y treated injuries of the m e d i a l collateral ligament. Various protocols involving the u s e of h i n g e d braces h a v e b e e n described for the t r e a t m e n t of all degrees of m e d i a l collateral l i g a m e n t injuries. T h e s e protocols are b e y o n d articles on t r e a t m e n t a n d rehabilitation of collateral l i g a m e n t injuries of the knee. Biomechanical studies of c o m m e r c i a l rehabilitative braces h a v e f o u n d that m o s t braces decrease b o t h translation a n d rotation c o m p a r e d w i t h the contracted limb. 21 These braces are, however, limited in n o r m a l w e i g h t - b e a r i n g conditions a n d are a p p r o p r i a t e l y u s e d for rehabilitation only.
Functional Braces Functional braces h a v e b e e n designed to a u g m e n t the stabi!Lity of unstable knees. T h e y are m o s t c o m m o n l y u s e d in the anterior-cruciate-deficient a n d anterior-cruciatereconstructed knee. Functional braces h a v e b e e n s h o w n to d e c r e a s e the load on the m e d i a l collateral l i g a m e n t 4,5 a n d m a y be useful in certain situations for protection w h e n the athlete returns to competition. The significantly higher e x p e n s e o f t h e s e braces often restricts their use to the BRACING FOR COLLATERAL LIGAMENT INJURIES
REFERENCES 1. Drez D, Jr (ed): Knee Braces: Seminar Report. Chicago, IL, American Academy of Orthopaedic Surgeons, 1985 2. Fetto JF, Marshall JL: Medial collateral ligament injuries of the knee: A rationale for treatment. Clin Orthop 132:206-217, 1978 3. Feagin JA: The Crucial Ligaments: Diagnostic and Treatment of Ligamentous Injuries About the Knee. New York, NY, Churchill Livingstone, 1988 4. BakerBE, Van Hanswyk E, Bogosian S, et al: A biomechanical study of the static stabilizing effect on knee braces on medial stability. Am J Sports Med 15:566-570, 1987 5. Baker BE, Vanttanswyk E, Bogosian S, et al: The effect of knee braces on lateral impact loading of the knee. Am J Sports Med 11:345-348, 1983 6. Paulos LE, France EP, Rosenberg TD, et ah The biomechanics of lateral knee bracing: I. Response of the valgus restraints to loading. Am J Sports Med 15:419-429, 1987 7. France EP, Paulos LE, lagaraman G: The biomechanics of lateral knee bracing: IL Impact response of the braced knee. Am J Sports Med 15:430-438, 1987 8. Paulos LE, Cawley PW, France EP: Impact biomechanics of lateral knee bracing: The anterior cruciate ligament. Am J Sports Med 19:337-342,1991 9. Erickson AR, Tasuda K, Beynnon B, et al: An in vitro dynamic evaluation of prophylactic knee braces during lateral impact loading. Am J Sports Med 21:26-35, 1993 207
10. Teitz CC, Hermanson BK, Kronmal RA, et al: Evaluation of the use of braces to prevent injury to the knee in collegiate football players. J Bone Joint Surg 69A:2-9,1987 11. Grace TG, Skipper BJ, Newberry JC, et al: Prophylactic knee braces and injury to the lower extremity. J Bone Joint Surg 70A:422-427, 1988 12. Hewson GR, Mendini RA, Wong JB: Prophylactic knee bracing in college football. Am J Sports Med 14:262-266, 1986 13. Rovere GD, Haupt HA, Yates CS: Prophylactic knee bracing in college football. Am J Sports Med 15:111-116,1987 14. Requa RK, Garrett JG: Clinical significant and evaluation of prophylactic knee brace studies in football. Clin Sports Med 9:853-869, 1990 15. Sitler S, Ryan J, Hopkinson W, et al: The efficiency of a prophylactic knee brace to reduce knee injuries in football: A prospective randomized study at West Point. Am J Sports Med 18:310-315,1990 16. Albright JP, Powell JW, Smith W, et ah Medial collateral ligament knee sprains in college football: Effectiveness of preventative braces. Am J Sports Med 22:12-18, 1994 17. Highgenboten CL, Jackson A, Meske N, et al: The effects of knee brace wear on perceptive and metabolic variables during horizontal treadmill runners. Am J Sports Med 19:639-643,1991 18. Styf JR, Nakitostie M, Gershuri D: Functional knee braces increase intramuscular pressures in the anterior compartment of the leg. Am J Sports Med 20:46-49, 1992
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19. Zetterlund AE, Serfass RC, Hunter RE: The effect of wearing the complex Lenox Hill Derotation Brace on energy expenditure during horizontal treadmill running at 161 m/rain. Am J Sports Med 14:73-76, 1986 20. Houston ME, Goemans PH: Leg muscle performance of athletes with and without knee support braces. Arch Phys Med Rehabi163:431-432, 1982 21. Cawley PW, France EP, Paulos LE: Comparison of rehabilitative knee braces: A biomechanical investigation. Am J Sports Med 17:141-146, 1989 22. Hughston JC, Andrews JR, Cross MJ, et al: Classification of knee ligament instabilities, Part II. The lateral compartment. J Bone Joint Surg 58A:173-179, 1976 23. Baker CL, Norwood LA, Hughston JC: Acute posterolateral rotatory instability of the knee. J Bone Joint Surg 65A:614-618, 1983 24. Grood ES, Noyes FR, Butler DL: Ligamentous and capsular restraints preventing medial and lateral laxity in intact human cadaver knees. J Bone Joint Surg 63A:1257-1269,1981 25. Gollehan DL, Torzilli PA, Warren RF: The role of the posterolateral and cruciate ligament instability of the human knee. J Bone Joint Surg 69A:233-242,1987 26. DeLee JD, Riley MB, Rockwood CA: Acute straight lateral instability of the knee. Am J Sports Med 11:404-411, 1983
TIMOTHY B. SUTHERLAND