Three-dimensional computed tomography-based comparison reveals divergent patellar and tibial tubercle behaviour between lateral closed-wedge and medial open-wedge high tibial osteotomy.

PURPOSE: This study aimed to compare three-dimensional patellar and tibial positional changes after medial open-wedge high tibial osteotomy (MOWHTO) and lateral closed-wedge high tibial osteotomy (LCWHTO) using computed tomography. METHODS: This retrospective comparative cohort study included 18 patients who underwent high tibial osteotomy for medial knee osteoarthritis (9 MOWHTO, 9 LCWHTO). LCWHTO was selected for patients with patellofemoral joint degeneration, patellofemoral cartilage injury, anterior knee pain or correction angle ≥10°; MOWHTO was selected for the remaining patients. Full-length lower-limb computed tomography scans were obtained preoperatively and at 1 year postoperatively. Displacement and rotation of the patella and distal tibial fragment were quantified in the anterior-posterior, medial-lateral and proximal-distal directions and in the internal-external, varus-valgus and flexion-extension rotations and compared between groups. RESULTS: In the MOWHTO group, the patella shifted distally (1.2 ± 1.9 mm) with internal (3.0° ± 1.9°) and valgus (1.9° ± 1.5°) rotation, whereas in the LCWHTO group it shifted proximally (1.6 ± 1.9 mm) with minimal rotation (proximal-distal displacement, p = 0.017; internal-external rotation, p < 0.001). The distal tibial fragment moved distally (3.5 ± 1.5 mm) with valgus rotation (8.1° ± 2.2°) in the MOWHTO group, but anteriorly (1.3 ± 0.7 mm), medially (6.7 ± 2.3 mm) and proximally (5.1 ± 2.2 mm) with internal rotation (4.5° ± 3.3°) in the LCWHTO group (all translations, p < 0.001; internal-external and varus-valgus rotation, p < 0.01). Patellar distalization and internal rotation correlated with tibial fragment distalization only in the MOWHTO group. CONCLUSION: MOWHTO and LCWHTO produced distinctly different three-dimensional positional changes of the patella and distal tibial fragment. These positional findings provide a mechanistic basis for individualised surgical decision-making, but their direct impact on PF cartilage status and long-term outcomes requires confirmation in future studies. LEVEL OF EVIDENCE: Level III, retrospective comparative cohort study.