Anteromedial osteotomy and distraction are associated with greater posterior tibial slope increase after medial open-wedge high tibial osteotomy: A retrospective comparison of three techniques.

PurposeTo compare three medial open-wedge high tibial osteotomy (MOWHTO) techniques with respect to posterior tibial slope (PTS) preservation, coronal alignment correction, patellar height, and clinical outcomes.MethodsThis retrospective comparative study included 62 patients who underwent MOWHTO for medial compartment knee osteoarthritis with varus malalignment. Patients were grouped by osteotomy technique: monoplane anterior to the medial collateral ligament (MCL) (Group A, n=22), biplane anterior to the MCL (Group B, n=18), and monoplane posterior to the MCL (Group C, n=22). Radiographic outcomes included mechanical axis, PTS, Caton-Deschamps index, Insall-Salvati index, and Kellgren-Lawrence grade. Clinical outcomes included Lysholm and visual analog scale scores.ResultsAll groups achieved significant mechanical-axis correction (all p<0.001). Mean PTS increased in Groups A and B (+2.12°±3.22° and +3.39°±2.76°, respectively) but decreased in Group C (-0.88°±3.78°; between-group p<0.001). Group C showed significantly lower PTS change than Group A (p=0.011) and Group B (p<0.001). This effect remained significant after adjustment for age, sex, follow-up duration, preoperative PTS, correction magnitude, and preoperative Kellgren-Lawrence grade.ConclusionAnteromedial monoplane and biplane MOWHTO were associated with greater postoperative PTS increases than the posterior monoplane technique, despite comparable coronal alignment correction among the groups.