Mechanisms of Anterior Cruciate Ligament Tears in Professional National Basketball Association Players: A Video Analysis

A systematic search was performed of online databases for any anterior cruciate ligament (ACL) injuries within the NBA. Video was obtained of injuries occurring during competition and downloaded for 2-dimensional video analysis. Thirty-five in-game videos were obtained for analysis. Of the reviewed cases, 19% were noncontact ACL injuries where there was no player-to-player contact from an opposing player. Three injury mechanism categories were found based on the events at the point of initial ground contact of the foot of the injured limb: single-leg casting (mean dorsiflexion angle 18.9 degrees (14.4 degrees); mean knee flexion angle 15.6 degrees (7.8 degrees); and mean trunk lateral flexion 18.2 degrees (8.4 degrees)); bilateral hop (mean dorsiflexion angle 18.2 degrees (15.2 degrees), mean knee flexion angle 21 degrees (14.5 degrees), mean trunk extension angle 6.9 degrees (11.4 degrees), and landing angle from the athlete's center of mass 47.9 degrees (10.1 degrees)); and single-leg landing after contact (mean abduction angle of the swing leg 105.4 degrees (18.1 degrees), mean knee flexion angle of the injured limb 34.2 degrees (8.0 degrees), and mean trunk ipsilateral flexion angle 22.2 degrees (7.0 degrees)).