Risk of revision in UKA versus HTO: a nationwide propensity score-matched study

Introduction Our study aims to investigate the incidence rate and risk factors for subsequent revision in patients treated with UKA compared with those treated with HTO. Methods In this retrospective nationwide cohort study, we used data from the Korean National Health Insurance claims database from January 1, 2009 to December 31, 2017. We compared patients who had undergone UKA or HTO as the primary surgical procedure longer than two years prior. We used multivariable logistic regression models to compare risk of revision between the groups after propensity matching with inverse probability of treatment weighting (IPTW). Revision was defined as conversion to total knee arthroplasty (TKA) after primary UKA or HTO. Results In this study, 73,902 patients with UKA and 72,215 patients with HTO were identified after applying IPTW. The risk of revision during the entire study period was higher for patients with HTO than for patients with UKA (adjusted hazard ratio [HR] = 1.42). Kaplan-Meier 8-years survival was 96.8% in the UKA group and 95.1% in the HTO group. Patients with HTO who were at higher risk of revision had advanced age (60-69 years [HR = 2.17, 95% CI 1.76-2.67] and 70-79 years [HR = 2.89, 95% CI 1.81-4.62]), female sex (HR = 1.41, 95% CI 1.19-1.66), CHF (HR = 3.12, 95% CI 1.25-7.78), COPD (HR = 1.68, 95% CI 1.34-2.10), PVD (HR = 1.75, 95% CI 1.10-2.78), and CVA or TIA (HR = 1.87, 95% CI 1.13-3.08) compared with those with UKA. Conclusion Risk of revision was higher for patients with HTO than for patients with UKA. Risk factors for subsequent revision in patients with HTO were advanced age (60-69, 70-79), female sex, and comorbidities such as CHF, COPD, PVD, CVA, or TIA. However, orthopedic surgeons should also consider that TKA conversion from UKA has higher risk of revision than TKA conversion from HTO before choosing between UKA and HTO.