Fig. 4

Radiographs illustrate the case of a 21-year-old male patient who had bilateral ankylosing spondylitis (AS). a An AP view of both hips before surgery shows the narrowed hip joint spaces, damaged femoral head, and Dorr type C femoral bones. b A pelvic X-ray taken immediately after surgery showed that the initial stability of the acetabular cup and short stem were achieved by press fit and good canal filling of the short stem. c An AP view of both hips taken 1 year postoperatively reveals that the acetabular cup and stems are well fixed in a good position in both hips. Grade 2 calcar resorption is evident in both hips, but periprosthetic bone stock is preserved without stress shielding-related bone osteopenia. d An AP view of both hips taken 8 years postoperatively demonstrates that the femoral components are in a satisfactory position without osteolysis and subsidence. Note the radiographic signs of calcar rounding and the increase in bone density in this area. No component migrated superiorly or medially