A biomechanical analysis of two functional knee braces.

The influence of knee bracing was evaluated during the activity of running by examining ground reaction forces and knee joint movement parameters assessed electrogoniometrically. Twenty-one subjects were assigned to 1 of 3 groups based on medical records provided by a physician: normal or non-injury group; anterior cruciate ligament lesion/laxity group; and anterior cruciate ligament repair group. Four test conditions were investigated: healthy or control limb; injured or experimental limb; Generation II knee brace; and Marquette Knee Stabilizer knee brace. Ten running trials were performed for each condition at a photoelectrically controlled running pace (3.33 +/- 0.11 m X s-1). There were no significant differences as a result of group membership for both electrogoniometer and force platform analyses (P less than 0.05). There was a significant difference across the four test conditions. Both knee brace applications were shown to significantly reduce knee flexion during swing and support, total rotation, and total varus/valgus movement parameters of the experimental knee joint. Both brace applications were also shown to alter the experimental limb by increasing the relative time to the achievement of the initial collision force, creating a greater collision force and thereby creating larger impulses in both the vertical and foreaft directions during the initial contact phase.