The anterior cruciate ligament enigma - Injury mechanisms and prevention

The reasons for the higher frequency of anterior cruciate ligament injuries in women are largely conjecture. These injuries may result from direct con tact or, more frequently, from no direct contact to the knee during activit ies that most athletes consider routine to their sport. This implies that t here are intrinsic factors that lead to anterior cruciate ligament rupture. For the anterior cruciate ligament to tear, there must be excess anterior tibial translation or rotation of the femur on the tibia. In the former cas e, the tibia can move anteriorly during quadriceps activation that is not c ounterbalanced by hamstring activation. Patients describe their injury as o ccurring when landing, stopping, or when planting to change directions. The knee typically was near full extension. Mechanically, the angle of the pat ellar tendon and tibial shaft increases as the knee approaches full extensi on. This gives a mechanical advantage to the quadriceps. During cutting man euvers, athletes tend to cut with a knee near extension (0 degrees-20 degre es) when the quadriceps are active and the hamstrings are neither very acti ve nor at a knee flexion angle that offers much of a mechanical advantage. In performing cutting and landing maneuvers, women tend to perform the acti vities more erect; that is, with their knees and hips closer to extension, One possible factor to help reduce the frequency of anterior cruciate ligam ent injuries in women may be in proper instruction for performing cutting a nd landing maneuvers which will lower their center of gravity thereby denyi ng the quadriceps the opportunity to shift the tibia anteriorly.