Cementless Modular Total Hip Arthroplasty with Subtrochanteric Shortening Osteotomy for Hips with Developmental Dysplasia

Background: The purpose of this retrospective study was to analyze the functional and radiographic results of cementless, modular total hip arthroplasty combined with subtrochanteric osteotomy for the treatment of patients who had had Crowe Group-IV developmental dysplasia of the hip as a child. Methods: Twenty-five consecutive patients (thirty-three hips) who had previously had Crowe Group-IV developmental dysplasia of the hip were treated with a modular cementless prosthesis at a mean age of sixty years. The mean follow-up period was eight years (range, five to eleven years). The acetabular cup was placed in the position of the anatomical hip center in every patient. Subtrochanteric femoral shortening osteotomy was performed with use of a step-, cut design. Results: The mean Merle d'Aubigne and Postel hip score improved from 9 to 16 points (out of a maximum of 18 points). The mean limb-length discrepancy in seventeen patients with unilateral involvement was reduced from 5.1 cm (range, 3.7 to 6.5 cm) to 2.8 cm (range, 1.4 to 4.6 cm). Two,patients had a positive Trendelenburg sign, and three had a slight limp at the time of the latest follow-up. No cases of nonunion or nerve palsy were encountered. Postoperative dislocations occurred in two hips. One hip showed progressive radiolucent lines around the proximal femoral sleeve within two years after the surgery, and this was followed by progressive stem subsidence. Only one femoral stem was revised. Conclusions: Cementless, modular total hip arthroplasty combined with subtrochanteric osteotomy for the treatment of patients with prior Crowe Group-IV developmental dysplasia of the hip resulted in satisfactory outcomes. Hips with poor bone quality and a developmentally short femoral neck present technical challenges with regard to achieving sufficient rotatory stability, following osteotomy, for osseointegration of the modular implants.