An in vitro dynamic evaluation of prophylactic knee braces during lateral impact loading

To determine the ability of prophylactic knee braces to reduce or limit medial collateral and anterior cruciate ligament elongation under dynamic loading conditions, we used cadaveric specimens that had a surrogate soft tissue material that matched the tissue compliance of in vivo contracted muscles. Eight cadaveric specimens were fitted with four pro phylactic knee braces and instrumented with Hall Effect Strain Transducers on both the medial collateral and anterior cruciate ligament. Each specimen was mounted in a testing frame while a lateral impact was applied to the knee joint by a pendulum at levels below the injury threshold. Legs were tested at 0° and 30° of knee flexion, both with and without an intact anterior cruciate ligament. The maximum elongation for each ligament was cal culated as a percentage of the initial measured length. The addition of a prophylactic knee brace significantly reduced the level of impact force at the point of impact, but this did not result in a significant reduction of anterior cruciate ligament elongation for any test. Al though not significant, all braces tested were more effective at reducing medial collateral ligament elonga tion during a lateral impact with the knee flexion at 30° than at 0°.