Swing phase control with knee friction in juvenile amputees.

Above-knee amputees have a slower than normal walking velocity. In conventional prostheses the solution has been to apply knee friction to attempt to match the cadence of the prosthetic limb to the sound limb. Using kinematic data, we investigated the effect of variable knee friction on the swing phase of gait in juvenile amputees. The subjects were instructed to walk at a comfortable pace and were tested repeatedly with varying amounts of knee friction. We found that the excursion of the prosthetic shank as measured by knee range of motion was altered by changing the amount of knee friction. The period of the prosthetic shank remained constant when measured as a physical pendulum and when measured dynamically during gait. Therefore, knee friction is an effective means of providing the amputee with a more symmetrical appearing gait by matching the heel rise of the prosthetic limb to the sound limb. It is not an effective means, however, of matching the cadence of the prosthetic limb to the sound limb.