Demographic, comorbidity, and episode of care trends in unicompartmental knee arthroplasty: 2008 to 2018.

Purpose: The purpose of this study is to assess how unicompartmental knee arthroplasty (UKA) patient demographics, comorbidities, and episode of care outcomes have changed from 2008 to 2018 in order to better understand the impact of recent changes in healthcare ideology on UKA.

Methods: The National Surgical Quality Improvement Program was queried to identify demographics, comorbidities, and episode of care outcomes in patients undergoing primary UKA from 2008 to 2013 (n = 3096) vs 2014-2018 (n = 9073). Trends were analyzed using Student's t-tests for continuous variables and Chi-squared tests and Fisher's exact tests for categorical variables.

Results: When comparing the years 2008-2013 to 2014-2018, there was no clinically significant difference in age, body mass index (BMI), proportion of patients with a BMI > 40 kg/m, percentage of diabetes (15.0% vs 15.5; p = 0.715), smoking status (10.2% vs 9.4%; 0.177), COPD (3.0% vs 2.8%; p = 0.645), CHF within 30 days (< 0.1% vs 0.2%; p = 0.060), or acute renal failure (0.0% vs < 0.1%; p = 0.621) in patients undergoing UKA. However, the rate of patients with dyspnea, (5.7% versus 3.6%; p < 0.001), anemia (9.4 versus 7.3%; p < 0.001), and overall morbidity/mortality probability have improved, with a decrease in hospital LOS (2.2 ± 1.9 days versus 1.4 ± 2.1 days; p < 0.001) and an increase in home-discharge (90.7% versus 95.2%; p < 0.001).

Conclusion: From 2008 to 2018, there was minimal improvement in UKA patients' modifiable comorbidities. However, despite the lack of significant change in patient health status, our findings showed improvement in episode-of-care outcomes, implying that the value of UKA has been increasing over the last decade.