Mid-term results of total hip replacement with subtrochanteric osteotomy, modular stem, and ceramic surface in Crowe IV hip dysplasia.

BACKGROUND: Total hip athroplasty (THA) in Crowe IV developmental dysplasia of the hip (DDH) presents many challenges for surgeons with regard to acetabular and femoral deformities. The purposes of this study are to (1) report the mid-term results of THA with subtrochanteric transverse osteotomy using S-ROM prosthesis and ceramic-on-ceramic (COC) surface for Crowe type IV DDH; and (2) compare the wear performance between COC and metal-on-polyethylene (MOP) bearing couple.

METHODS: Eighty Crowe IV DDH patients (103 hips) treated with cementless THA were retrospectively reviewed. The S-ROM prosthesis was used in all the hips and subtrochanteric osteotomy was performed in 74 hips. COC and MOP bearing surfaces were compared through the evaluation.

RESULTS: At mean follow-up of 65.6 months, the mean Harris hip score improved from 54.2 to 87.7 points; however, Trendelenberg sign positive was confirmed in 20.4% of the hips. Postoperative dislocation occurred in 6 cases and overall 4 hips were revised. With any component revision as endpoint, Kaplan-Meier survival curve showed that 8-year cumulative survival rate in the COC group was 97.2% and 9-year survival rate in the MOP group was 85.9%. The mean linear wear rate for COC and MOP surface was 0.006 and 0.175 mm/y, respectively.

CONCLUSIONS: Subtrochanteric osteotomy combined with the modular S-ROM prosthesis and COC surface in Crowe IV DDH has achieved satisfactory mid-term results. However, postoperative dislocation and limp remain major complications. Linear wear rate for MOP surface is high and the long-term prosthesis survival is affected. Ceramic or highly cross-linked polyethylene should be preferred.