Muscle power compensatory mechanisms in below-knee amputee gait

Objective: This three-dimensional and bilateral gait study on five below-kn ee amputees was undertaken to demonstrate the following: (1) how hip muscle powers can compensate for the lack of ankle function on the amputated side ; and (2) how these compensatory mechanisms can influence muscle power acti vities in the sound limb. Design: Gait data were assessed by an eight-camera high-speed video system synchronized to two force plates. The three-dimensional mechanical muscle p owers were calculated at the joints of the lower limbs. Significant differe nces between each limb were determined using the Student's t test for paire d data with P < 0.05. Results: In the absence of ankle plantar flexor power, hip extensors and fl exors as well as hip external rotators became the major power generators, w hereas hip abductors and adductors and knee extensors muscle powers became the main source of absorption. For the sound limb, increased hip extensor a ctivity was observed, accompanied by less hip abduction-adduction activity. Conclusions: Perturbations in below-knee amputee gait affected the hip musc le powers on the amputated side in all three planes, although the hip front al plane balance was modified in the sound limb.