Functional knee brace migration: Biomechanical and neuromuscular alterations

Functional knee bracing has been shown to alter lower limb joint mechanics, which may protect the anterior cruciate ligament. Many knee braces have been studied, however, the effects of brace alignment or brace type on lower limb joint mechanics are not known. This study was conducted to determine whether the use of a functional knee brace, the type of brace used or its alignment relative to the knee causes biomechanical or neuromuscular alterations to gait. Ten healthy participants took part in all conditions: walking with a shell and soft shell brace, each aligned according to the manufacturers' specifications; walking with each brace distally misaligned by 1 cm as well as walking without a brace. A motion analysis and force plate system was used to determine the three-dimensional angular impulse, peak joint moments and peak joint angles of the ankle, knee and hip. Electromyographic data were used to support the kinetic data. All data were time normalized to one stride. In addition, kinetic data were normalized to body mass and kinematic data were normalized to the standing position. In comparison to unbraced walking, the shell brace in its aligned position significantly reduced the peak ankle plantarflexor moment. Additionally, there was a decreased peak knee flexion angle with the aligned shell and soft shell braces as well as an increased peak knee adduction angle and a reduced peak knee internal rotation angle with the aligned shell brace. Although there were alterations in lower limb mechanics during walking, induced primarily by the shell type functional brace, these changes were not deemed to considerably alter joint loading at the knee