Functional and Radiographic Outcomes of Proximal Fibular Osteotomy in Medial Compartment Knee Osteoarthritis: A Prospective Single-Arm Interventional Study With 12-Month Follow-Up

Background Medial compartment knee osteoarthritis (OA) is a common degenerative joint disorder and a major cause of chronic pain and functional impairment, particularly among middle-aged and older adults. In low-resource healthcare settings, access to procedures such as knee arthroplasty remains limited. Proximal fibular osteotomy (PFO) has emerged as a minimally invasive, joint-preserving surgical technique that may improve load distribution across the knee and correct varus alignment in selected patients. Objective This study aimed to assess the functional and radiological outcomes of PFO in patients with medial compartment knee OA at the 12-month follow-up. Methods A hospital-based prospective single-arm interventional study was conducted among 42 patients with Kellgren-Lawrence grade II-III medial compartment knee OA who underwent PFO at a tertiary care center in Nepal. The primary outcome was the change in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score at 12 months. Pain intensity was assessed using the Visual Analog Scale (VAS). Radiological parameters included medial joint space width and tibiofemoral varus angle. Patients were evaluated at six and 12 months postoperatively. The Wilcoxon signed-rank test was used for non-normally distributed variables (VAS and WOMAC), and paired t-tests were used for normally distributed radiological parameters. Statistical significance was set at p<0.05. Results The mean age of participants was 56.90±9.33 years. Significant improvements were observed at 12 months. The mean VAS score decreased from 7.29±1.13 preoperatively to 3.33±1.76 (p<0.001). The mean WOMAC score improved from 75.36±8.68 to 33.60±12.94 (p<0.001). The medial joint space width increased from 2.04±0.39 mm to 3.74±0.46 mm (p<0.001), and the tibiofemoral varus angle improved from 8.44°±2.29° to 4.40°±2.43° (p<0.001). Excellent functional improvement (≥75% reduction in WOMAC score) was achieved in 61.9% of patients. The overall complication rate was 19%, with most complications being minor and transient. Conclusions PFO was associated with significant improvements in pain, functional outcomes, and radiological parameters at 12 months in this cohort, with an acceptable complication profile. These findings suggest that PFO may be a useful joint-preserving option in selected patients with medial compartment knee OA, particularly in resource-limited settings. However, results should be interpreted cautiously due to the single-arm study design and lack of a comparator group.