OBJECTIVETo develop the techniques of total hip arthroplasty(THA) for Crowe type IV developmental dysplasia of the hip (DDH) with S-ROM prosthesis,and to assess its clinical results.

METHODSFrom October 2000 to October 2011,30 patients (36 hips) with Crowe type IV DDH underwent THA,including 6 patients with bilateral hip involved and 24 patients with unilateral. S-ROM prosthesis was adopted together with subtrochanteric transverse osteotomy. All the cementless acetabular cups were placed at the original anatomic location. The threaded cups were put in or near the level of the true acetabulum in all patients. Full coating stems were used in femoral side. All the patients were evaluated by using the Modified Harris Hip Score. Radiographic evaluations were made preoperatively and during follow-up.

RESULTSTwo patients lost of follow-up. Twenty-seven patients with 32 hips were followed up,and the average duration was 48 months (ranging from 7 to 84 months). There was 1 patient with bilateral THA died from hemorrhagic shock. Two patients could walk freely with the visible fracture lines at 12th and 18th months postoperatively. There were no complications such as infection or nerve injuries. Modified Harris Hip Score improved from preoperative 41.7+/-3.7 to postoperative 89.1+/-2.9. There was no acetabular or femoral component revision because of mal-position or loosening of the prostheses in all patients. Postoperative X-ray showed that all the prostheses in place,good integration between acetabular cups,femoral prosthesis and host bone without loosening. All bone grafts were integrated. All the hips acquired union of osteotomy and bone in-growth. None of the patients had radiographic evidence of aseptic loosening of prosthesis.

CONCLUSIONFor the complex DDH, follow methods should be used to improve therapeutic effects:good exposure of the true acetabulum,deepen acetabulum, femoral shortening, oblique osteotomy, using the S-ROM prosthesis.