Unicompartmental Knee Arthroplasty vs Total Knee Arthroplasty: A Risk-adjusted Comparison of 30-day Outcomes Using National Data From 2014 to 2018

BACKGROUND: When clinically indicated, the choice of performing a total knee arthroplasty (TKA) vs a unicompartmental knee arthroplasty (UKA) is dictated by patient and surgeon preferences. Increased understanding of surgical morbidity may enhance this shared decision-making process. This study compared 30-day risk-adjusted outcomes in TKA vs UKA using a national database. METHODS: We analyzed data from the National Safety and Quality Improvement Program database, for patients who received TKA or UKA between 2014-2018. The main outcomes were blood transfusion, operation time, length of stay, major complication, minor complication, unplanned reoperation, and readmission. Comparisons of odds of the outcomes of interest between TKA and UKA patients were analyzed using multivariate regression models accounting for confounders. RESULTS: We identified 274,411 eligible patients, of whom 265,519 (96.7%) underwent TKA, while 8892 (3.3%) underwent UKA. Risk-adjusted models that compared perioperative and postoperative outcomes of TKA and UKA showed that the odds of complications such as blood transfusion (adjusted odds ratio [aOR], 19.74; 95% confidence interval [CI]: 8.19-47.60), major (aOR, 1.87; 95% CI: 1.27-2.77) and minor complications (aOR, 1.43; 95% CI: 1.14-1.79), and readmission (aOR, 1.41; 95% CI: 1.16-1.72) were significantly higher among patients who received TKA than among those who received UKA. In addition, operation time (aOR, 7.72; 95% CI: 6.72-8.72) and hospital length of stay (aOR, 1.11; 95% CI: 1.05-1.17) were also higher among the TKA recipients compared to those who received UKA. CONCLUSIONS: UKA is associated with lower rates of adverse perioperative outcomes compared to TKA. Clinical indications and surgical morbidity should be considered in the shared-decision process