Lower Extremity Alignment and Dynamic Control With Associated Injury Risk in College Athletes With Knee Hyperextension

Knee hyperextension, also called genu recurvatum or back knee, is commonly seen in women, people with ligamentous laxity, stroke and cerebral palsy patients. This faulty posture would result in excessive tension of the passive tissues such as anterior cruciate ligament (ACL) and posterior capsule of the knee. Subjects may also develop compensations at hip and ankle joint, as well as lower extremity malalignment. Muscles surrounding the knee could also become dysfunctional when performing functional tasks requiring stability during terminal knee extension, during which uncontrolled knee hyperextension could easily be utilized to lock the joint for stability in gait and stair climbing. In athletes, landing from a jump on an extended knee is one of the common reasons resulting in ACL injury. Little is known about the injury rate of athletes with knee hyperextension who participate in sports involving jump-landing activities. The aim of the study is to explore if knee hyperextension is associated with poor lower extremity alignment and dynamic control and injury rate in athletes requiring jump-landing activities. One of the study hypothesis is that athlete with knee hyperextension can find more compensatory lower extremity alignments and poor control in dynamic movement than control group. The other hypothesis is with or without knee hyperextension, the parameter of lower extremity alignment and dynamic control can predict injury rate in jump landing athlete.