Immediate effects of a knee brace with a constraint to knee extension on knee kinematics and ground reaction forces in a stop-jump task.

BACKGROUND A small knee flexion angle in landing tasks was identified as a possible risk factor for noncontact anterior cruciate ligament injuries that are common in sports. HYPOTHESIS A specially designed knee brace with a constraint to knee extension would significantly increase the knee flexion angle at the landing of athletic tasks preceded with horizontal movement components, such as stop-jump tasks. STUDY DESIGN Repeated measure design for brace effects. METHODS Three-dimensional videographic and force plate data were collected for 10 male and 10 female recreational athletes performing a stop-jump task with and without the specially designed brace. Knee flexion angle at landing, maximum knee flexion angle, and peak ground reaction forces during the stance phase of the stop-jump task were determined for each subject with and without the knee brace. RESULTS The knee brace decreased the knee flexion angle at the landing by 5 degrees for both genders but did not significantly affect the peak ground reaction forces during the landing. CONCLUSIONS The specially designed knee brace may be a useful device in the prevention and rehabilitation of noncontact anterior cruciate ligament injuries in sports.