Effect of Asymmetric Knee Height on Gait Asymmetry for Unilateral Transfemoral Amputees

Transfemoral prostheses have traditionally sought to emulate symmetry in their designs. Using a symmetric prosthesis for a physically asymmetric unilateral transfemoral amputee typically causes asymmetric gait patterns. This research study investigates the effects of prostheses with lower knee heights than the intact knee and a pilot study of the combined effects of adding distal mass with lower knee heights. To test the effects, one unilateral transfemoral amputee was tested with four different knee heights as well as with and without a distal mass. Further, six able-body subjects were tested while wearing prosthetic simulators with three different knee heights and no distal mass. The results showed that the amputee and able-body subjects wearing prosthetic simulators showed better overall symmetry with lower knee heights in spatiotemporal, kinematic, and kinetic parameters. Specifically, the amputee showed improved symmetry in step length and kinetics. The addition of distal mass in combination with lower knee height showed better symmetry than cases without distal mass for the amputee gait. The kinematics showed decreased hip angles in all cases. The tests with the prosthetic simulators showed decreased knee and ankle angles. This study indicates that there are potential benefits to overall gait symmetry by lowering the knee height of a unilateral transfemoral prostheses. The study also showed that changes in distal mass in combination with lower knee height can improve gait symmetry.