If a product does not address sitting stability and comfort, it is not adequate. This provides the patient with maximum functioning and helps prevent contractures and compression of internal organs. The bases of this cornerstone, the ischials, also are the most vulnerable areas for skin breakdown and are the fulcrum points for pelvic rotation. To keep the pelvis in place, the fulcrum action of the ischials must be stopped by eliminating pressure on them. The pelvis can be stabilized by providing a firm, flat support under the entire length of the femurs, particularly in the proximal femur closest to the pelvis.
Support here controls the position of the pelvis while controlling rotation of the entire femur.
The femur shelf must be wide enough to fully support the femur and must fit as close to the ischials as possible without touching them. This maximizes control of the stability of the body by taking advantage of the full length of the femur for support. If the cushion is too short, the legs are more free to move out of position. If cushion is too long, it can push against the back of the knee and the lower leg, pulling the body out of position. Footrest height Footrests should be adjusted so that the knees are even with the hips, making the femurs parallel to the ground.