Depending on the amount, speed and direction of energy, various patterns of subtrochanteric fracture occured. But it is difficult to stabilize the fractured fragments which was comminuted and under the muscular antagonistic force. It Is important to obtain early ROM and early weight bearing for old aged patient, but difficult to stabilize the subtrochanteric fracture due to senile osteoporosis and characteristics of comminution. And we experienced subtrochanteric fracture of femur which was already ankylosed state and treated by total hip replacement using by long stem and supporting ring.