The knee is removed. A bk amputation allows saving the knee and usually some part of the tibia bone that goes down to the foot. This will also allow the prostheses to be less complex and more functional because the entire knee joint is not part of the prosthesis. Of course, if the pathology present in the leg requires an ak amputation, the surgeon will inform you; but it's always better to save the knee if possible.
Surgical excision. During an above the knee amputation, the involved limb is resected at a level above the level of the knee.