Survival and Risk Factor Analysis of Open Wedge Tibial Osteotomy for Medial Unicompartmental Osteoarthritis

Purpose: The purpose of this study was to evaluate the mid to long-term clinicoradiological results of open wedge high tibial osteotomy performed as the primary treatment for medial unicompartmental osteoarthritis of the knee and to analyze the factors that affect the survival rate. Materials and Methods: The study cohort consisted of 124 patients who underwent open wedge high tibial osteotomy for medial unicompartmental osteoarthritis of the knee and had a minimum follow-up period of five years. Hospital for special surgery (HSS) and the Western Ontario and MacMaster (WOMAC) scores, tibiofemoral angle, mechanical axis of lower limb, medial proximal tibia angle, and tibia posterior slope angle were used to evaluate the clinical and radiographic outcomes over the mean follow-up period of 85 months. The risk factors that affected the survival rate were calculated by multivariate regression analysis. Results: Mean HSS scores and WOMAC scores showed significant improvements at the final follow-up. The tibiofemoral angle was improved to 8.4 degrees of valgus after surgery. A total of 12 patients (9.7%) failed to survive until the final follow-up resulting in 8 year survivorship of 90.3%. Risk factors significantly affecting the survival rate afteropen wedge high tibial osteotomy included a high body mass index (BMI), severe varus deformity, severe osteoarthritis (Kellgren-Lawrence Grade III or IV) preoperatively and overcorrection angles in operation. Conclusion: Open wedge high tibial osteotomy showed good clinical and radiological outcomes in the current study. Analysis of the risk factors influencing survivorship after open wedge high tibial osteotomy suggests that the surgical procedure be avoided or modified with patients who have a high BMI, severe varus deformity, or severe osteoarthritis symptoms preoperatively.