Hip disarticulation is performed for proximal malignant tumors of the lower extremity with extensive involvement of the underlying femur in addition to the soft tissues, so that they are not amenable to a lesser procedure. It is performed for tumors more distal than those requiring a hemipelvectomy and more proximal than those that can be treated with a high thigh amputation. Rather than hip disarticulation, some surgeons prefer to do a conservative hemipelvectomy, preserving the entire iliac crest. The conservative hemipelvectomy is done faster (as one has to go through less musculature) and provides greater margins. The functional difference between a conservative hemipelvectomy and hip disarticulation is small, although the hip disarticulation does allow easier fitting with a prosthesis. Tumors that are located in the mid thigh with extensive involvement of the soft tissues and the underlying femur may be treated with hip disarticulation, as may tumors proximal to this level but well below the level of the inguinal ligament (Fig. 53.1).