Prognostic Factors for Open-Wedge High Tibial Osteotomy with Spacer Implantation in Patients with Medial Compartmental Knee Osteoarthritis

Abstract

Background: To identify the medial open-wedge high tibial osteotomy (MOWHTO) prognostic factors with wedge-shaped spacer implantation (spacer-type MOWHTO) for varus medial compartment knee osteoarthritis.Methods: Patients who underwent spacer-type MOWHTO between August 2018 and September 2019 were prospectively enrolled in this study. Patients were divided into two groups based on Western Ontario and McMasters University Osteoarthritis Index (WOMAC) scores of 40 points at 1 year postoperatively: the effective group (n=88, 84.6%), with post-WOMAC scores 40 or less, and the invalid group (n=16, 15.4%), with post-WOMAC scores more than 40. The variables assessed at baseline and 1 year postoperatively including age, sex, body mass index (BMI), Kellgren-Lawrence (K-L) grade, hip-knee-ankle angle (HKAA), medial proximal tibial angle (MPTA), posterior tibial slope angle (PTSA), Blackburn-Peel index (BPI), duration of symptoms and WOMAC score, were compared. Prognostic factors were analyzed using logistic regression, and the corresponding odds ratios were also calculated.Results: A total of 104 patients were enrolled in the study protocol at 1 year postoperatively. The WOMAC score decreased from 72.39±12.95 at baseline to 20.06±12.96 at 1 year postoperatively. The preoperative varus was corrected to a neutral position or to mild valgus. In addition, the PTSA was decreased. At the same time, the patellar height was not significantly changed postoperatively. Univariate analysis revealed that the significant predictors of the WOMAC score were age >70 years, BMI >30 kg/m², K-L grade IV, and pre-HKAA >10° (P<0.1 for all). Multivariable logistic regression analysis revealed that age>70 (OR=4.861) and K-L grade IV (OR=6.590) were significantly associated with the WOMAC score at 1 year postoperatively.Conclusion: Spacer-type MOWHTO is an effective treatment for osteoarthritis with varus deformity. The prognostic factors for spacer-type MOWHTO were age and K-L grade.Level of evidence: III