We hypothesized that insults to the knee as significant as an ACL rupture and reconstruction would alter motor performance and the relative contributions of the knee and hip musculature during the squat exercise. Specifically, we believed that our postoperative subjects would adopt a movement strategy that increased the hip extensor moments of force and decreased the knee extensor moments of force in their injured limb during performance of the maneuver. To characterize these relative contributions, we report the bilateral lower-extremity kinematics and kinetics of postoperative ACL reconstruction patients during performance of the back squat exercise.