The influence of prophylactic ankle bracing on knee joint moments and ground reaction force during an unanticipated 90° side-step cutting

Because of the high incidence of ankle sprains, prophylactic ankle braces have been used to reduce the ankle sprains. Changes in kinematics and kinetics at the ankle occurring with prophylactic bracing may increase the possibility of knee injury specifically an anterior cruciate ligament (ACL) tear by transferring greater forces to the knee and increasing knee joint loadings. The purpose of this study was to determine the influence of prophylactic ankle bracing on knee joint kinetics and ground reaction force during an unanticipated 90° side-step cutting task in order to assess knee mechanics relevant to potential ACL injury risk. The data from 30 subjects (15 men and 15 women) were used for data analyses and post processing. This study did not find any influence of bracing on the ground reaction forces, but 33% increase in knee internal rotation moment when wearing ankle braces was observed (p < 0.003). These results suggest that ankle bracing impose greater stress on the ACL during the 90° side-step cutting task and may place an individual at a greater risk for noncontact ACL injury.