RESUMO
Twelve anterior cruciate ligament (ACL)-deficient subjects performed concentric isokinetic knee extensions at maximum effort both with and without the Bledsoe Pro Shifter knee brace. Electromyogram signals from the quadriceps, hamstrings, knee angle, and the extension force were recorded and evaluated to determine the effects of such dynamic bracing on muscle activity and joint stability. High activity, or asymptomatic, subjects (n = 5) experienced no change in muscle activity, but displayed a decrease in extension force throughout the active range of the brace. Low activity, or symptomatic, subjects (n = 7) exhibited increased quadriceps activity and decreased hamstrings activity, and displayed a minor increase in force in the mid-range (80 degrees to 40 degrees flexion). These results indicate that dynamic bracing prevents quadriceps inhibition in symptomatic subjects by exerting a posteriorly directed force to the superior tibia; thus, the brace compensates externally for the absence of the ACL.
