Dynamic electromyography in active and limited walking below-knee amputees

Walking electromyography was performed in 12 below-knee amputees, who were amputated for peripheral vascular insufficiency. All were at least 1 year post-surgery and had no problems with the fit of their prostheses. Seven were community walkers and five were limited household ambulators. The quadriceps and hamstring muscles exhibited electrical activity during 60% and 64.7% of the gait cycle, respectively, in the active walkers, compared with 44.6% and 53.8% in the limited walkers. Quadriceps muscle activity was initiated almost 10% earlier in the active walkers, while hamstring muscle initiation was similar in both groups. The active walkers were able to maintain quadriceps and increase hamstring muscle activity to compensate for their absent ankle motors, while the limited walkers showed decreased activity in both muscle group. The results of this preliminary study suggest that the dysvascular limited walking below-knee amputee does not use the quadriceps and hamstring muscles for propulsion during walking, and does not appear to reap the benefits of knee joint preservation.