Originally Posted by frost

Rotationplasty (e.g. Van Nes Rotation) - a procedure where the leg is amputated above the knee, the lower portion of the leg is rotated 180° and reattached - the ankle acts like a knee joint, providing extra function; more mobility and better control with a prosthesis.

One of the most important things with Rotationplasty is getting the most 'range of motion' as possible. The more range of motion - the more bending you have.

Your knee can extend straight out. When you bend your knee as far as you can bend it from a straight position, this is your Range of Motion. Your ankle is not use to fully extend (as a ballerina), so you don't have much Range of Motion when you bend it. This means it's harder to bend your leg completely for running, sitting, etc. Although your prosthetic can be designed to help with the difference, with Rotationplasty it's important to work at getting the most range of motion as possible with your ankle.