Prostheses alignment: effect on gait of persons with below-knee amputations.

This study investigated the effect on gait of changing prosthetic alignment for five people with amputations. Three-dimensional angular kinematic data were recorded by electrogoniometers positioned at their hips and knees. Indices of symmetry were developed in time and frequency domains for motion data of lower limbs when walking. These measures of symmetry were determined at different prostheses alignment settings and used to assess the possibility of aligning below-knee prostheses on the basis of symmetry of lower limb motion. Optimal or neutral alignment of below-knee prosthesis, as selected by clinically experienced personnel, tended to minimize asymmetry of gait at the hips and knees for persons with below-knee amputations. The indices of symmetry showed that alignment changes to the prosthetic foot disrupt gait to a greater extent than do other alignment changes. Asymmetries of hip flexion-extension motions were more sensitive to alignment changes than were other asymmetries. An index was selected that showed sensitivity to changes in gait caused by changes in prosthetic alignment for below-knee amputations. Refinements and other applications of this index in rehabilitation are suggested.