Knee Joint Motion Quantified Using the Finite Helical Axis Method

The knee is a complex joint comprised of two main bones (femur and tibia) that articulate in a stable manner through the support of surrounding meniscus, musculature, and ligaments. The anterior cruciate ligament (ACL) is one of the main ligaments connecting the femur to the tibia. The ACL restricts anterior translation of the tibia with respect to the femur and aids in preventing internal and external rotation. The ACL is the most commonly injured ligament in the knee [1] and has been shown to increase the risk of cartilage degeneration leading to osteoarthritis (OA) [2]. The mechanics of the joint are altered following an ACL rupture, but the relations between the resulting joint instability and OA are not well understood.