Medial open-wedge high tibial osteotomy alters sagittal tibial tubercle–trochlear groove distance

Medial open-wedge high tibial osteotomy (MOWHTO) is widely used to treat varus knee osteoarthritis, but its impact on patellofemoral biomechanics remains incompletely understood. In particular, the sagittal tibial tubercle–trochlear groove (sTT-TG) distance, a novel parameter linked to patellofemoral contact pressure, has not been evaluated in this context. This study aimed to assess changes in sTT-TG following MOWHTO and identify anatomical predictors of its postoperative magnitude. In this retrospective study, 34 knees from 33 patients (mean age 36.6 ± 9.5 years, mean BMI 26.2 ± 4.3 kg/m²) undergoing ascending biplanar MOWHTO with pre- and postoperative MRI and radiographs were analyzed. The sTT-TG, Caton–Deschamps Index (CDI), posterior tibial slope (PTS), and tibiofemoral rotation angle (TFRA) were measured. Correlation and multivariable regression analyses were performed to identify predictors of postoperative sTT-TG. MOWHTO significantly decreased the sTT-TG distance from 6.25 ± 5.34 mm to 3.74 ± 6.81 mm (p = .009), indicating anteriorization of the tibial tubercle. Patellar height (CDI) decreased from 1.14 ± 0.20 to 0.99 ± 0.15 (p < .001), and TFRA was reduced from 4.74 ± 5.54° to 2.62 ± 5.50° (p = .017). Multivariable regression identified preoperative sTT-TG, postoperative medial PTS, and CDI as independent predictors of postoperative sTT-TG (adjusted R² = 0.697). A steeper medial PTS and lower patellar height were associated with greater tibial tubercle anteriorization. MOWHTO resulted in a significant anteriorization of the tibial tubercle in the sagittal plane. Postoperative sTT-TG is strongly influenced by tibial slope and patellar height, emphasizing the need to account for these factors during surgical planning, particularly in patients with patellofemoral cartilage changes. Future biomechanical studies should explore the clinical relevance of these changes on joint loading.