Fig. 2

a Preoperative anteroposterior radiograph of the left hip showing avascular necrosis of the femoral head. b Immediate postoperative anteroposterior radiograph showing a well-fixated metal-on-metal articulated total hip arthroplasty. c–f An anteroposterior radiograph of the right hip at 3, 5, 11, and 22 years after operation, 5 years after surgery we can see osteolysis around the cup (white arrow). g Immediate postoperative frog-view radiograph. h A frog-view radiograph of the right hip at 22 years after operation, showing an obvious notch at the anterior part of the neck of the femoral stem (red arrow)