High tibial osteotomy yields sufficient clinical and radiological results in varus knee correction regardless of the site of deformity

Purpose: High tibial osteotomy (HTO) can alleviate symptoms and slow osteoarthritis progression in selected patients with arthritic varus knees. However, the role of postoperative joint line obliquity (JLO) in correcting varus deformity remains unclear. The aim of this study was to evaluate clinical and radiological outcomes of HTO—lateral closing-wedge (LCW-HTO) and medial opening-wedge (MOW-HTO)—in treating varus knees with tibial- and femoral-based deformities, considering JLO boundaries (≤4°). Methods: A retrospective analysis was performed on 99 patients (108 knees) with varus knees (preoperative hip-knee-ankle angle [HKA] ≤ 175°) undergoing HTO. Patients were classified into femoral-based (FEM-Var) or tibial-based (TIB-Var) varus groups, regardless of the surgical technique. Radiographs were analysed preoperatively and at the final follow-up (mean, 9 ± 4.2 years; range, 2–18 years). Clinical outcomes were assessed using the Hospital for Special Surgery score, International Knee Documentation Committee score, Tegner score, Numeric Rating Scale, and Crosby-Insall score. Results: The cohort had a mean age of 49.4 ± 10.2 years (range, 18–64 years) at the time of initial follow up. Sixty-eight knees (63%) underwent LCW-HTO, and 40 (37%) underwent MOW-HTO. The mean HKA improved from 172° ± 4.1° (range, 162°–175°) preoperatively to 178° ± 3° (range, 176°–180°) postoperatively. Most patients achieved a JLO ≤ 4° (TIB-Var: two patients > 4°; FEM-Var: five patients > 4°). The TIB-Var group demonstrated superior JLO correction (mean postoperative JLO: TIB-Var, 2.9° ± 1.5°; FEM-Var, 3.5° ± 1.6°; p < 0.01) and greater changes in the joint line congruency angle (JLCA). Both groups showed significant improvements in all clinical scores (p < 0.01), with no osteoarthritis progression at the last follow-up. Conclusion: HTO is an effective procedure for treating pathological varus knees, regardless of the site of the deformity. Both FEM-Var and TIB-Var groups showed comparable improvements in the clinical scores, development of osteoarthritis, and the restoration of a neutral mechanical axis. Notably, the TIB-Var group showed superior correction in JLO and achieved better postoperative JLCA than the FEM-Var ones. Level of Evidence: Level IV, cohort study.