Control of the posterior tibial slope (PTS) is crucial in high tibial osteotomy (HTO), since unintended changes can alter the normal knee kinematics and ligament loading. This study investigated the influence of sagittal cutting plane orientations on PTS in bi-planar medial open wedge HTO (MOWHTO) on a Sawbone model. Sixty Sawbone® left-tibia models (A Pacific Research Company, USA) were used to perform biplanar MOWHTO with three sagittal orientations: (1) parallel to the medial tibial plateau (PO); (2) 10° anterior-inclined osteotomy (AIO); (3) 10° posterior-inclined osteotomy (PIO). The biplanar cut was performed distal to the tibial tuberosity in half the specimens and proximal in the remainder. Customized 3D-printed cutting guides ensured reproducibility. PTS and valgus correction were measured pre- and post-osteotomy using a navigation system. Group- and subgroup-specific ΔPTS were analyzed using a Bayesian multilevel model. Minimal clinically important difference (MCID) was set at 2.5°. Bayesian “power” analysis (assurance) was used to assess the sensitivity of ΔPTS and pairwise differences relative to the MCID. Across the three sagittal orientation and their distal/proximal subgroups, ΔPTS and pairwise ΔPTS did not exceed the predefined MCID of 2.5°. Bayesian assurance of equivalence exceeded 86% in every unit and pairwise comparison, indicating a high confidence that the evaluated HTO configurations are clinically equivalent with respect to ΔPTS. In this experimental study, different sagittal osteotomy inclinations in MOWHTO showed no clinically relevant changes in posterior tibial slope. No significant differences were observed across sagittal cut orientations or ATT levels. In vitro biomechanical study.
Gurbanov et al. (Thu,) studied this question.