SACH-SAWCH

One big problem for us with Inman's (and Braun & Fischer) works was that the subjects were neurologically normal. There is an entire dimension missing as to what happens when neurology drifts from the evolved ideal of control perfection? For lower leg amputees Inman found that normal gait requirements were attainable by having the prosthetic foot solidly attached at a specific angle ( knee center ahead of ankle center over mid-foot) [shin is NOT VERTICAL, A right angle is a wrong angle . Handle the ankle capacitor and cushioning heel landing by using a wedge of cushion in the heel of the wooden foot (soft pliable toe area). This was the SACH foot prosthesis. Solid Ankle Cushion Heel A 'cushion' is only a cushion if it regains its height by midstance. Less than that it is a back rolling missing heel -a rocker. Not good. Let's look at a very minimal case that shows vividly what SACH really is.

A girl who was born with a missing forefoot but totally normal otherwise. She has a very tiring asymmetrical gait barefoot or in shoes with filler (on the side requiring it). Her walk was not evenly forward and her inability to step fully with her seemingly INTACT right side drew attention and wonder. This right step is well under expected length (arrow points to normal heel contact expected). {75% of radius stature – see mud}