From the gait laboratory to the rehabilitation clinic: translation of motion analysis and modeling data to interventions that impact anterior cruciate ligament loads in gait and drop landing.

In female athletes the risk of anterior cruciate ligament (ACL) injury during impact-related activities such as landing is higher compared to males. Both how and why this occurs has been at the forefront of orthopedic sports medicine research over the past 20 years. Many individuals with an ACL-deficient knee compensate for joint instability in an effort to remain physically active. Yet others do not compensate and are faced with a reduction in their activities and/or meniscus tears and eventually osteoarthritis. In this article we attempt to link 2 distinct but related scientific disciplines (in vivo motion analysis assessment and computational modeling) to show how these techniques have emerged as powerful tools in our understanding of knee function. Normal knee function and the biomechanics of the ACL-deficient (ACLd) and ACL-reconstructed (ACLr) knee are summarized. Basic experiments concerning the mechanism of noncontact ACL injury as well as performance adaptations in ACLd and ACLr knees are reviewed, and the biomechanics of the normal, ACLd, and ACLr knees under more strenuous activities, such as landing from a jump, are provided.