The results of monoblock stem with step-cut femoral shortening osteotomy for developmentally dislocated hips.

INTRODUCTION: The main objective of this study was to evaluate the midterm results of cementless THA with the use of monoblock stems combined with step-cut femoral shortening derotational osteotomy for DDH.

MATERIALS AND METHODS: A total of 66 hips of 49 patients with Crowe type IV developmental hip dislocation, with a mean follow-up of 90 (range 26-207) months, were reviewed retrospectively. Subtrochanteric step-cut shortening osteotomy and monoblock femoral stems were used. The cup was placed in the true acetabulum in all cases. 21 hips had previous femoral valgisation osteotomies. Anteroposterior and lateral radiographs of both hips were obtained preoperatively and at the last follow-up examination. The Harris Hip Score (HHS) was used for pre- and postoperative clinical evaluation.

RESULTS: The mean HHS increased from 49 to 86 points. A total of 13 hips of 10 patients (the isolated acetabular component in 7 hips of 6 patients, the femoral component in 3 hips of 3 patients, and both components in 2 patients) were revised during the follow-up period. Dislocation occurred in 3 hips, deep periprosthetic infection in 2, superficial wound infection in 2, and femoral vein injury and sciatic nerve palsy in 1. Nonunion was observed in 3 osteotomy sites. 10-year survival probabilities of 91% for femoral components for all cases and 78% for acetabular components were found.

CONCLUSIONS: THA with subtrochanteric femoral shortening osteotomy was proven to be an effective technique for avoiding neurological complications for Crowe IV DDH. Cementless THA with the use of monoblock stems showed overall survival rates of 95% at 5 years and 85% at 10 years.