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Comparable clinical outcomes but increased technical difficulty after total hip arthroplasty following curved
Kimihiro Oono1, Yusuke Osawa2, Hiroto Funahashi1
1Department of Orthopaedic Surgery, Nagoya University, Nagoya, Japan.
Background:
Total hip arthroplasty (THA) is technically challenging after curved intertrochanteric varus osteotomy (CVO) for osteonecrosis of the femoral head (ONFH) due to altered proximal femoral morphology, which might compromise clinical outcomes, implant alignment, and accurate leg length restoration. In this study, we aimed to compare the clinical outcomes and radiographic findings among patients undergoing THA after CVO and primary THA for ONFH.
Methods:
This retrospective case-control study included 28 hips that underwent THA after CVO (CVO group) and 56 propensity score-matched primary THA cases for ONFH (primary group). The clinical outcomes were assessed by the Harris Hip Score (HHS), complication rates, and implant survivorship. The radiographic parameters included cup inclination and anteversion, stem alignment, and postoperative leg length discrepancy (LLD).
Results:
The CVO group showed longer operative time and greater blood loss than did the primary group (p < 0.01). However, no statistically significant differences were found in HHS, complication rates, or implant survival. The CVO group showed a higher rate of stem malalignment (25.0% vs. 12.5%, p < 0.01) and greater LLD (6.1 ± 5.2 mm vs. 2.8 ± 3.3 mm, p < 0.01). In the CVO group, cemented stems demonstrated significantly lower malalignment rates (10.5% vs. 66.7%, p < 0.01) and smaller LLD (3.8 ± 4.4 mm vs. 11.0 ± 3.2 mm, p < 0.01) than cementless stems.
Conclusions:
THA after CVO provided clinical outcomes and survival rates comparable to those of primary THA for ONFH. However, altered femoral morphology increased the risk of stem malalignment and LLD. Cemented stems might improve implant alignment and leg length restoration in these challenging cases.