One of the more serious problems with above-knee prosthetic devices is their weight, since there is no musculature aside from the lower back, hip, and thigh to operate it, and because the amount of mass that has to be moved about is already large, the question of how to power motors large enough to be of use becomes principal. It's easy to forget the effect that a weighty full-leg prosthesis can have on the lower back, too, particularly if it's a massive one.

It's even worse if one considers below-knee prostheses, about which I know considerably more, since I wear one myself. However, given a proper fit and good suspension, of which neither is a "given," power-assist is really not needed once one has a reasonably modern foot.

I'm just curious how the OP intends to power an above-knee prosthesis and where he proposes to put the motors, batteries, etc. Motors and batteries are generally either weak or heavy and sometimes too muc of both.

RE