The Clinical and Radiological Outcomes of Subtrochanteric Osteotomy in Crowe Type IV Hip Dysplasia: A Comparison of Three Different Stem Designs

Aims: The purpose of this study was to determine whether there are differences in clinical and radiographic outcomes among three different stem designs for subtrochanteric osteotomy in Crowe type IV developmental dysplasia of the hip (DDH). Methods: A retrospective analysis of prospectively collected data was undertaken from a consecutive series of 37 Crowe type IV DDHs treatment of noncemented total hip arthroplasty with chevron subtrochanteric osteotomy in 30 patients. Patients are divided into three groups, including Ribbed group (using Link Ribbed stem; n = 14), Synergy group (using Synergy stem; n = 9), and Link Classic Uncemented (LCU) group (using LCU stem; n = 14), according to the design of the stem. The clinical and radiographic outcomes were evaluated. Results: All patients were followed for 36 months. The time of bone union of the LCU stem was significantly longer than that of the Synergy stem (P = 0.02) and the Ribbed stem (P > 0.05); the time of bone union of the Ribbed stem was longer than that of the Synergy stem (P > 0.05). The length of stem in the distal femur of the Ribbed stem (P = 0.000) and the Synergy stem (P = 0.001) is significantly longer than that of the LCU stem. There were three hips with malunion, stem loosening, and varus alignment, which were observed in the LCU stem. None of these were observed in Ribbed and Synergy stems. In total hip arthroplasty with a noncemented stem combined with subtrochanteric femoral osteotomy for Crowe IV DDH, 89.2% hips (33/37) can achieve good and excellent clinical outcomes. There were three hips (1 hip in the Ribbed stem and two in the LCU stem) with fair clinical outcomes and one hip (LCU stem) with poor clinical outcomes. Conclusions: Although Ribbed, Synergy, and LCU stems have similar clinical outcomes, the LCU stem has a tendency to a varus position, longer union time, malunion, and stem loosening, when compared with the Ribbed and Synergy stems. We recommend against adoption of the LCU stem for Crowe IV DDH with subtrochanteric femoral osteotomy.