Navigation-assisted curved intertrochanteric varus osteotomy for osteonecrosis of the femoral head

Curved intertrochanteric varus osteotomy (CVO) is a joint-preserving procedure for osteonecrosis of the femoral head (ONFH). Computer-assisted navigation may improve osteotomy accuracy, but its clinical benefit remains uncertain. This study aimed to evaluate the clinical outcomes of navigation-assisted versus conventional CVO.

We retrospectively reviewed 58 patients (62 hips) who underwent CVO for nontraumatic ONFH during 2010-2023. Conventional CVO was performed in 2010-2018 (group C), whereas navigation-assisted CVO was performed since 2019 (group N). Clinical outcomes included operative time, blood loss, complications, Harris Hip Score (HHS), leg length discrepancy (LLD), and conversion to total hip arthroplasty (THA). Radiographic outcomes included intact ratio, collapse progression (> 3 mm), leg shortening, and femoral lateralisation. Outcomes were compared, and survivorship was evaluated using Kaplan-Meier analysis.

The HHS at one year postoperatively was higher in group N (87.6 ± 10.8) than in group C (81.1 ± 14.1; p = 0.048); no difference was observed at final follow-up. No significant between-group differences were observed in the postoperative intact ratio, collapse progression, or conversion to THA. However, leg shortening from preoperatively to bone union was smaller in group N than in group C (7.0 ± 5.0 vs. 11.9 ± 6.2 mm, p = 0.001), and subjective LLD was less frequent (group N: 10.0% vs. group C: 34.4%, p = 0.033).

Navigation-assisted CVO did not improve joint-preserving outcomes, including collapse progression or conversion to THA. Nonetheless, postoperative leg shortening and subjective LLD were significantly reduced, which may support better early postoperative hip function.