Fig. 1

a-c Radiographs show the case of a 48-year-old male patient who had osteonecrosis of both femoral heads. a AP view of the pelvis before surgery shows Steinberg Stage IV osteonecrosis of the right femoral head. b AP view of the pelvis taken 1 years postoperatively reveals that acetabular and femoral components are well fixed in a satisfactory position; the left hip shows Steinberg Stage V osteonecrosis of the left femoral head. c At 7-year follow-up AP view Grade 1 calcar resorption is evident in both hips, without signs of stem loosening and osteolysis