Combined anteversion technique in total hip arthroplasty for Crowe IV developmental dysplasia of the hip.

BACKGROUND: A high rate of postoperative dislocation in total hip arthroplasty (THA) for Crowe IV developmental dysplasia of the hip (DDH) has been reported, 1 of the main reasons being higher true acetabular anteversion. If the cup is fixed with normal anteversion, the anterior rim will be excessively exposed, which reduces the contact areas of the cup and bone, affects prosthesis stability, and leads to iliopsoas tendinitis and persistent hip pain after THA. The aim of this study was to demonstrate that when cup anteversion is larger, adjusting femoral anteversion to bring the combined anteversion (CA) into the "safe zone" might prevent dislocation. METHODS: After having fixed the cup in the acetabulum according to the patients' native acetabular anteversion, we shortened and rotated the proximal femur to reduce femoral anteversion, adjusting the CA into the "safe zone". The Harris Hip Score (HHS) was used to evaluate hip joint function. Computerised tomography scanning was used to measure the anteversion angles. RESULTS: All patients were followed up without any dislocation. Preoperative and 12 months after surgery, the mean HHS were 43.3 ± 2.6 (38-47) and 88.1 ± 3.3 (78-92) respectively. Pre- and post-operation, the mean CA angles were 88.6° ± 9.4° (80.3°-119.4°) and 49.2° ± 2.6° (43.4°-54.4°) respectively. The bone healing time of femoral osteotomy ranged from 4 to 14 months, with a mean time of 7.5 months. CONCLUSIONS: This CA technique in THA for Crowe IV DDH can effectively prevent postoperative dislocation and provide good hip function.