The effect of knee braces on lateral impact loading of the knee.

Disruption of the medial supporting structures of the knee occurs commonly in contact sports such as American football and lacrosse. A limited number of clinical and laboratory studies currently document the effectiveness of bracing. The purpose of this project was to determine if commercially available bracing could be shown to produce objective evidence of medial stabilization of the knee. Our model involves the use of a cadaver lower extremity with a fixed foot and suspended femur with a free knee and a lateral impact load applied simulating a clipping injury. Force transducers were placed on the ACL and medial collateral ligament (MCL) and an electrogoniometer was attached to the extremity. The prophylactic braces studied had a limited capacity to protect the MCL from direct lateral stress with the knee in full extension. In flexion or with a change in direction of the load, the protective effect is greatly reduced. The functional braces had a capacity to limit abduction and rotational stresses on the MCL in flexion and extension.

A biomechanical study of the static stabilizing effect of knee braces on medial stability.

The purpose of this project was to determine if commercially available braces could be shown to produce objective evidence of medial stabilization of the knee. Commercially available athletic braces were evaluated for their effect on abduction forces applied to a cadaver knee with no instability and with experimentally created medial instability. Under computer control, abduction forces were applied while simultaneous data were obtained from an electrogoniometer and transducers applied to the anterior cruciate ligament and the superficial medial collateral ligament at 0 degrees, 15 degrees, and 30 degrees of flexion. Our results showed a reduction in abduction angle using functional braces, whereas prophylactic braces demonstrated little or no protective effect.