Effect of Increased Coronal Inclination of the Tibial Plateau After Opening-Wedge High Tibial Osteotomy

Purpose: To assess whether the increased inclination of the tibial plateau on the coronal view after opening-wedge high tibial osteotomy affects radiographic coronal alignment, clinical outcomes, and cartilage findings. Methods: After adjustment for the preoperative medial proximal tibial angle (MPTA), patients who underwent opening-wedge high tibial osteotomy were retrospectively divided into those with postoperative MPTA values of 95 degrees or less (normal group) and greater than 95 degrees (increased group), with each group containing 43 knees. The 2 groups were compared regarding their arthroscopic cartilage findings at 1 year postoperatively and radiographic coronal alignment and clinical outcomes at 2 years postoperatively. Cartilage regeneration in the medial condyles and cartilage deterioration in the lateral condyles were evaluated at the time of second-look arthroscopy. Clinical outcomes were evaluated by the American Knee Society knee and function scores, Lysholm knee scoring scale, and Knee Injury and Osteoarthritis Outcome Score (KOOS). Results: The postoperative anatomic femorotibial angle in the increased group was lower than that in the normal group (P < .001), and the amount of overcorrection in the increased group was higher than that in the normal group (P < .001). The postoperative joint line obliquity in the increased group was higher than that in the normal group (P < .001). Cartilage regeneration in the medial condyles and deterioration in the lateral condyles did not differ significantly on the femoral and tibial sides between the groups. The postoperative American Knee Society knee score and KOOS sports and recreational function subscale score in the normal group were higher than those in the increased group (both P < .001). Conclusions: There were no significant differences in the changes in the appearance of the articular surfaces between the 2 groups at 1 year postoperatively. Patients with a postoperative MPTA greater than 95 degrees had more valgus alignment and higher joint line obliquity and had a lower KOOS sports and recreational function subscale score than patients with a postoperative MPTA of 95 degrees or less at 2 years postoperatively.