Surgical methods

Preoperatively, supine whole-leg radiographs were used to plan the osteotomy size for a target axial load goal of 57.5–62.5% [4]. Intraoperatively, an arthroscope was first used to evaluate the state of the cartilage, menisci, and ligaments. Depending on the condition of the knee joint, microfracture or meniscal procedures, such as a meniscectomy or meniscal repair, were performed. Then, according to a pre-surgical plan, either biplane or transverse osteotomy of the proximal tibia was completed, and intraoperative imaging was used to confirm lower extremity alignment and adjust osteotomy size. The portion of the proximal tibia that underwent osteotomy was filled with a 60% porosity β-tricalcium phosphate block and hydroxyapatite block and was fixed using a TriS Medial HTO plate (Olympus Terumo Biomaterials, Tokyo, Japan), Position HTO plate (B. Braun Aesculap, Tuttlingen, Germany), or TomoFix (DePuy Synthes, Bettlach, Switzerland).