Obtaining fixation in DDH with Surface arthroplasty (SA) with a two part polyethylene (PE ) socket was technically challenging. Although dislocation was rare there was a high loosening rate secondary to polyethylene wear. The purpose of this study was to evaluate the results of Conserve Plus metal-on-metal SA in Crowe class I and II Developmental Dysplasia of the Hip patients.

54 patients (59 hips), 72% females, average age43.7 years (15 to 63.8) met these inclusion creteria with 2 years of follow-up minimum. Seven hips were Crowe type II and fifty-two were type I.

Harlan C. Amstutz, John Antoniades, Michel J. Le Duff, Paul E. Beaulé

The results of MMSA are much improved over those of prior generations of SA and socket fixation is stable even in Crowe type II with the porous coated acetabular components without adjuvant fixation despite incomplete acetabular coverage of the socket. The hips have-been stable even with important range of motion. Recent short term failure and radiolucencies have been eliminated by improved technique despite a high incidence of femoral cysts and reduced area of fixation.

Introduction and Aims: Legg-Calve-Perthes disease and slipped capital femoral epiphysis are hip disorders that may result in the alteration of proximal femoral anatomy and subsequent osteoarthritis. LCP often results in a flattened head and short femoral neck; SCFE residual deformity is a retroverted head upon a wide femoral neck. Because of the low head to neck ratio and short neck length in these patients, surface arthroplasty is especially technically difficult.

Method: We examined a cohort of patients with either LCP or SCFE who underwent surface replacement of the hip to assess clinical results and identify pre-operative radiographic factors unique to this group. All patients with arthritis of the hip secondary to either LCP or SCFE, who underwent surface replacement between 1996–2002, were included. Proximal femoral anatomy was assessed by measuring the neck and head length, flattening of the head, anterior head offset and lateral head offset. Hip ROM was measured and SF-12 and UCLA Hip scores were calculated.

Results: Fourteen patients with LCP and 11 patients with SCFE had undergone surface replacement with an average age of 38 years; the mean time to follow-up was 26.2 months. Pre-operative radiographs revealed a head-neck ratio of 1.3 in the LCP group and 1.2 in the SCFE group. The amount of head offset was 9.4mm anterior and 6.4mm lateral in the LCP group; and 8.8mm and 4.4mm in the SCFE group. Neck and head length was 42mm in the LCP patients and 56.5mm in the SCFE patients; this measured 46 and 53mm post-operatively. No revisions had been performed in either group. The UCLA scores, SF-12 scores, and hip ROM did not differ from a cohort of patients who had undergone resurfacing for other reasons. No femoral neck fractures occurred in either group.

Conclusion: Despite technically difficult surgeries for hip resurfacing in these patients because of a flattened head and short neck in LCP, and wide femoral neck with retroverted heads in SCFE, the results to date have been good. By taking extra care to avoid notching the neck on the anterior and lateral tension sides, satisfactory results can be achieved.