Knee Ligament Ruptures and Orthotic Support

S tudies concerning ruptures of the knee's anterior cruciate ligament (ACL) arc helping us under­stand and treat this unfor­tunate and very common athletic injury. As a result of this research, chiroprac­tors may now be able to pre­vent (or at least minimize) many of these injuries. From a sports injury perspective, this is the best approach— prevent the problem, rather than try to salvage the knee after the damage has been done. Certain predisposing pos­tural factors can be identified in athletes, and preventive actions (such as custom orthotic support) can be taken. Non-Contact Causes Epidemiology and frequency studies have demonstrated that the vast majority of acute tears of the ACL occur without any contact or direct trauma to the athlete's knee.' While this seems contrary to the previous common under­standing of this problem, it has been found in several different studies. We now know that it is the torque, or twisting forces, imposed on the knee joint that cause some ACL's to rupture. Some ath­letes have knee joints that seem to be more susceptible to these torque forces, and certain sports activities have been identified as particularly problematic.-' Landing at foot strike with the knee extended or in slight flexion, at less than 20 degrees, and internally rotating the tibia in relation to the femur, is by far the most commonly described incident which results in tearing of the ACL.4 A rapid change in direction during running (or a • similar twist of the leg during a fall ski­ing) can produce just such an episode. This is especially true in sports that use shoe spikes, which fix the lower leg to the ground. Arnold, el«/., found that 81 percent of athletes with injury to the ACL recalled the moment of injury as having their tibia in internal rotation, combined with a sudden change of direction at foot strike.5 Markolf, cl at., used ca­daver specimens to measure the forces on the ACL with various types of loading. They found that internal ro­tation of the tibia places a greater force on the ACL than does external rotation. The greatest amount of strain occurred when the knee was hyperextended and in internal rotation. Forces were also quite high when the knee was in 10-degrees-or-less flexion, and internally rotated.'1 Predisposition Theories Numerous theories concerning factors that could predict which athletes would develop acute ruptures of the ACL have been investigated. A large discrepancy in the strength ratio between the quadri- ceps and hamstring muscles is only some­times present.7 Another theory (which is not well supported) is the greater fre­quency of internal derangement knee in­juries in people who are deconditioned and resume strenuous sports activities without proper conditioning." A more recent study by Beckett, et«/., retrospectively reviewed a group of ath­letes with acute, non-traumatic ACL rup­tures (arthroscopically proven), and compared them to a matched control group. These researchers found exces­sive pronation of the foot and collapse of the arch during weight bearing in the injured subjects, and proposed this find­ing as the mechanism of injury.1* Excessive Pronation and ACL Rupture Beckett, et«/., reviewed the biomechan-ics of the foot and ankle, and described how arch collapse and excessive prona- tion lead to abnormal internal (medial) tibial rotation, which "pre-loads" the an­terior cruciate ligament. Normally, subtalar joint pronation and internal ro­tation of the tibia occur only during the initial, contact phase, of gait. If prona­tion continues beyond the contact phase, the tibia will remain internally rotated. This abnormal tibial rotation transmits excessive forces upward in the kinetic chain to the knee joint, producing medial knee stresses, force vector changes in the quadriceps muscle, and lateral track­ing of the patella.'1 This theory is sup­ported by Copland's work, which found that passive tibial rotation was statisti­cally greater in hyperpronators than in nonpronators.1" Female athletes have an increased in­cidence of ACL rupture." Another study found that ruptures of the ACL in female athletes were directly correlated with the amount of arch collapse and hyperpronation.i: Beckett, et al.. conclude that "hyper-pronation of the foot and ankle complex may increase the risk of injury to the ACL'\S Prevention of ACL Ruptures The best type of treat- ment of athletic injuries is prevention. This is particularly true when the injury is one that may lead to permanent joint' instability—even with surgical repair— and could end an athlete's career, or limit a middle-aged runner's fitness program. With our current knowledge regarding the causes and predisposing factors for ruptures of the anterior cruciate ligament, we can now work to prevent these dev­astating injuries. All physically active patients and all local athletes should be examined and evaluated for the existence of excessive pronation of the foot and ankle. This is true for young athletes, as well as for weekend warriors. When you find an athlete with arch collapse and/or hyperpronation. the next step is to communicate and describe the risk factors for ACL rupture, then recom­mend the regular use of custom-made orthotics during all sports activities. Most manufacturers have orthotic mod­els designed specifically for athletes. The critical factors to look for in an orthotic for an athlete are shock absorption (with­out "bottoming out"), support for all three arches of the foot, moisture resistance, and little added weight. In addition, the athletic orthotic must have enough flex­ibility to be comfortable during intense activities, and yet have sufficient stabil­ity to prevent excessive pronation and tibial rotation. As Doctors of Chiropractic, we may be able to extend the competitive careers and active lifestyles of many in our communi- ties. When we recommend the use of orthotics, we may be preventing not just arch breakdown and biomechanical foot problems, but acute ruptures of the ACL, as well. Dr. John J. Danchik is the seventh in­ductee to the American Chiropractic As­sociation Sports Hall of Fame. He is the current chairperson oj the United States Olympic Committee s Chiropractic Selec­tion Program. He lectures extensively in the United States and abroad on current trends in sports chiropractic and reha­bilitation. Dr. Danchik is an associate editor of the Journal of the Neuro-musculoskeletal System and the Journal of Chiropractic Sports Injuries and Reha­bilitation. He has been in private prac­tice in Massachusetts for 23 years. You may reach Dr. Danchick at (617) 489-1220 or e-mail docforiocstxpaol. com. References l.McNair PJ. Marshall RN, Matheson JA. "Im­portant features associated with acute ante­rior cruciate ligament injury." NT. Medical Journal 1990; 14:537-539. 2.Fink C, Hoser C. Hackl W, el «/., "Long-term outcome of operative or nonoperative treat­ment of anterior cruciate ligament rupture — is sports activity a determining variable'.'" Ini J Sports Met! 2001: 22(4):304-309. 3.Simonsen EB, Mag-nusson SP. Bencke J. el al.. "Can the hamstring muscles protect the anterior cruciate ligament during a side-cut­ting maneuver?" Scaml J Met! Sci Sports 2000: 10(2):78-84. Whittington CF, Carlson CA. "Anterior cru­ ciate ligament injuries, arthroscopic recon­ struction and rehabilitation." Nursing Clin North Am 1991; 26:149-158. Arnold HA, et at., "Natural history of the anterior cruciate ligament." Am J Sports Med 1979; 7:305-313. Markolf KL, el «/.. "Direct measurement of resultant forces in the anterior cruciate liga­ ment." ./ Bone Joint Surgery 1990; 72:557- 567. Smillie IS. Injuries lo the Knee Joint (4th ed.). Baltimore: Williams & Wilkins. 1970:33-38. Beckett ME. et ul., "Incidence of hyperpronation in the ACL injured knee: a clinical perspective." J Athl Train 1992; 27:58-62. Tiberio D. "The effect of excessive subtalar joint pronation on patellofemoral mechan­ ics: a theoretical model." JOSPT 1987; 9:160- 165. 1 O.Copland JA. "Rotation motion of the knee: a comparison of normal and pronating sub­jects." JOSPT 1989; 10:366-369. 1 I.Harmon KG. Ireland ML. Gender differences in noncontact anterior cruciate ligament in­juries." Clin Sports Med 2000; "l9(2):287-302. l2.Ludon A. "Posture and ACL injuries in women." JOSPT 1996; 15:204-209.