Objective To the best of our knowledge, there has been no comparative study of changes in radiographic parameters in the sagittal plane between biplane opening wedge high tibial osteotomy (OWHTO) with plate fixation and uniplane OWHTO with spacer implantation. The aim of the study was to compare sagittal radiographs between the procedures of biplane and uniplane OWHTOs in patients with genu varum and to investigate the impact on the patellofemoral joint. Methods A retrospective study of 71 patients (58.0 ± 5.0 years of age, 58 females and 13 males) with varus‐aligned medial compartment knee osteoarthritis treated with OWHTO was performed during the period from January 2016 to February 2019. Thirty‐three patients underwent biplane osteotomy with plate fixation (biplane group), and 38 patients underwent uniplane osteotomy with absorbable wedged spacer fixation (uniplane group). Independent t tests were used to compare the two groups according to the preoperative and postoperative radiographic parameters of hip‐knee‐ankle (HKA) angle, posterior tibial slope (PTS), tibial tubercle prominence (TTP), Caton–Deschamps (CD) index, and Blackburne–Peel (BP) index. During the last follow‐up assessment, patients were asked to rate their patellofemoral joint status using the Samsung Medical Center (SMC) patellofemoral (PF) scoring system. The visual analog scale (VAS) was also used to rate knee joint pain when walking. Results There was no significant difference between the two groups in any of the demographic, clinical, or radiological characteristics at baseline (p > 0.05). Comparisons of postoperative sagittal radiographic parameters between patients in the uniplane group and patients in the biplane group showed significant differences in the PTS (13.4° vs 16.6°, t = 4.465, p < 0.001), TTP (9.0 mm vs 4.2 mm, t = 7.950, p < 0.001), and CD index (0.81 vs 0.70, t = 4.035, p < 0.001). At the final follow‐up assessment (minimum, 2 years), the SMC PF function score was significantly lower in patients in the uniplane group than in patients in the biplane group (27.8 vs. 32.1, t = 2.458, p = 0.016), but there were no significant differences in the SMC PF pain score or VAS score (p > 0.05). Conclusion The essential difference in the postoperative sagittal radiographic changes between biplane and uniplane OWHTO was the tibial tubercle prominence, indicating the posterior displacement of the tibial tubercle. Uniplane OWHTO may yield better function of the patellofemoral joint compared to biplane OWHTO.

Objective Uneven settlement of the proximal tibia significantly contributes to the onset and progression of medial compartment knee OA; however, the specific location and variations of proximal tibial deformity remain unclear. Therefore, this study aimed to explore the effects of the anatomic morphology of different tibial regions on proximal tibial vara and proximal tibial microstructural changes with age in both sexes to reveal the pattern of uneven settlement of the proximal tibia. Methods In this retrospective study, we reviewed the radiographs of 414 patients (789 legs) between May and September 2021. The medial proximal tibial angle (MPTA) and four anatomic angles of the tibia (i.e., the tibial plateau‐epiphyseal line [PT‐EL] angle, epiphyseal line‐tibial platform [EL‐PF] angle, epiphyseal axis inclination angle [EAIA], and subepiphyseal axis inclination angle [SAIA]) were measured. The effect of each angle on MPTA and their changes with age in both sexes were investigated using Pearson's correlation coefficient and multiple linear regression. Results In females, PT‐EL angle, EL‐PF angle, and SAIA negatively correlated with MPTA (r = −0.325, −0.246, and −0.502; p < 0.05), and EAIA positively correlated with MPTA (r = 0.099, p < 0.05). Regression analysis showed that the correlations between MPTA and PT‐EL angle, EL‐PF angle, and SAIA were significant (β = −1.003, −0.013, and −0.971; adjusted R2 = 0.979). Furthermore, MPTA negatively correlated with age (r = −0.202, p < 0.05); PT‐EL angle and EAIA positively correlated with age (r = 0.237 and 0.142, p < 0.05). Regression analysis showed that only the correlation between PT‐EL angle and age was significant (β = 5.635, p < 0.05). In males, PT‐EL angle, EL‐PF angle, and SAIA negatively correlated with MPTA (r = −0.270, −0.267, and −0.533; p < 0.05), and EAIA positively correlated with MPTA (r = 0.135, p < 0.05). Regression analysis showed that the correlations between MPTA and PT‐EL angle, EL‐PF angle, and SAIA were significant (β = −0.992, −0.017, and −0.958; adjusted R2 = 0.970). However, there was no significant correlation between age and any of the measured angles (p > 0.05). Conclusions Proximal tibial vara is affected by the anatomic morphology of the epiphyseal and subepiphyseal regions. In females, the uneven settlement of the epiphysis progresses with age and may be responsible for dynamic varus deformity of the proximal tibia.