Erschienen in:
29.08.2016 | Orthopaedic Surgery
What factors predict the failure of curved intertrochanteric varus osteotomy for the osteonecrosis of the femoral head?
verfasst von:
Toshiaki Okura, Yukiharu Hasegawa, Daigo Morita, Yusuke Osawa, Naoki Ishiguro
Erschienen in:
Archives of Orthopaedic and Trauma Surgery
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Ausgabe 12/2016
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Abstract
Introduction
The purpose of this study was to examine the 10-year survivorship and clinical outcome after curved intertrochanteric varus osteotomy (CVO) for the osteonecrosis of the femoral head (ONFH), and to determine what factors predict the failure of this procedure.
Materials and methods
We retrospectively reviewed 102 consecutive CVOs in 93 patients diagnosed with ONFH. Mean follow-up duration was 10.1 years (3.0–23.2 years). Factors associated with radiographic failure (secondary collapse and/or osteoarthritic change), conversion to total hip arthroplasty (THA) and low Harris Hip Score (HHS), were assessed. The Kaplan–Meier method was used to estimate survival rate.
Results
Radiographic failure occurred in 27 hips (26.5 %), and 11 hips (10.8 %) were converted to THA. The 10-year survival rate was 91.0 % [95 % confidence interval (CI) 83.4–95.2 %] with conversion to THA as the endpoint and 72.4 % (95 % CI 62.3–80.3 %) with radiographic failure as the endpoint. Mean HHS improved from 70.0 preoperatively to 88.1 at the final follow-up (p < 0.001). Multivariate Cox regression analysis showed that postoperative intact ratio <33.3 % [hazard ratio (HR), 11.17; 95 % CI 4.14–30.14] and center-edge (CE) angle <25° (HR 4.91; 95 % CI 1.92–12.55) were independent factors determining radiographic failure. In addition, the multivariate Cox regression analysis showed that postoperative intact ratio <33.3 % (HR 10.65; 95 % CI 2.24–50.53) and CE angle <25° (HR 7.81; 95 % CI 2.17–28.07) were also factors determining conversion to THA. Worse HHSs of <80 were seen in patients with postoperative intact ratio <33.3 % (p < 0.001), CE angle <25° (p < 0.001), and acetabular head index <75 % (p = 0.006).
Conclusions
Postoperative intact ratio <33.3 % and CE angle <25° were identified as independent factors determining radiographic failure and conversion to THA. Therefore, these factors must be taken into consideration when selecting patients for CVO.