Patient-Specific Instrument Guided Double Chevron-Cut Distal Femur Osteotomy

Abstract

The risk of non-union and prolonged periods of protected weight-bearing still remain unsolved issues after distal femur osteotomy (DFO). To improve the stability, we developed the double chevron-cut technique, which is a modified medial closing-wedge DFO guided by a patient-specific instrument. The purpose of this study was to investigate the feasibility and outcome of this operative approach. Twenty-five knees in twenty-three consecutive patients with genu valgum and lateral compartment osteoarthritis that received double chevron-cut DFO were included. The target of correction was 50% on the weight-bearing line (WBL) ratio. Patient-reported outcomes included the Oxford Knee Score (OKS) and the 2011 Knee Society Score (KSS). The mean of the WBL ratio was corrected from 78.7% ± 12.0% to 48.7% ± 2.9% postoperatively. The mean time to full weight bearing was 3.7 ± 1.4 weeks. Union of the osteotomy was achieved at 11.3 ± 2.8 weeks. At a mean follow-up of 17 months, the OKS improved from a mean of 27.6 ± 11.7 to 39.1 ± 7.5 (p = 0.03), and the KSS from a mean of 92.1 ± 13.0 to 143.9 ± 10.2 (p < 0.001). Three patients developed complications, including one case of peri-implant fracture, one of loss of fixation, and one of non-union. The double chevron-cut DFO followed by immediate weight-bearing as tolerated is effective in treating genu valgum deformity and associated lateral compartment osteoarthritis.