Abstract / Summary
Objective This study aimed to evaluate the effectiveness of medial open wedge high tibial osteotomy (MOWHTO) in patients with medial unicompartmental knee osteoarthritis (OA) and mild to moderate varus deformity. Methods A retrospective analysis was conducted on knee OA patients who underwent MOWHTO between January 2019 and January 2021, with a minimum follow-up of two years. Patients with medial unicompartmental knee osteoarthritis of Kellgren–Lawrence grade II–III were categorized by preoperative hip–knee–ankle (HKA) angle into mild varus (0° < HKA < 5°) and moderate varus (5° ≤ HKA < 10°) groups. The mild varus group included 30 patients (mean age, 57 ± 6 years), and the moderate varus group included 30 patients (mean age, 58 ± 5 years). Pre- and postoperative assessments included radiographic evaluations, arthroscopic findings, and clinical outcome measures. Results Both groups demonstrated significant postoperative changes in HKA angle and weight-bearing line ratio, together with a significant increase in medial joint space width ( P < 0.05). The distribution of Kellgren–Lawrence grades shifted toward lower grades at the 2-year assessment in both groups. Similarly, second-look arthroscopy at two years showed a shift toward lower International Cartilage Repair Society (ICRS) grades in both groups, with no statistically significant between-group differences ( P > 0.05). Both groups demonstrated significant improvements in Short Form-12 (SF-12) and Knee Injury and Osteoarthritis Outcome Score (KOOS) measures ( P < 0.05), while no statistically significant between-group differences were detected in postoperative KOOS or SF-12 scores ( P > 0.05). Changes in KOOS and SF-12 scores exceeded the minimal clinically important difference (MCID) thresholds in both groups. Conclusion MOWHTO was associated with favorable short-term outcomes in carefully selected patients with medial compartment knee osteoarthritis and mild or moderate varus deformity. No statistically significant differences in postoperative outcomes were detected between the two groups. Further comparative studies are required to determine the relative effectiveness of MOWHTO in patients with mild varus alignment.