Abstract
Primary total knee arthroplasty (TKA) has shifted from inpatient to outpatient facilities in the United States, driven by surgical advances, the 2018 Center for Medicare & Medicaid Services inpatient-only list change, and COVID-19 pressures. Limited national data and unclear patient profiles in outpatient facilities versus hospitals prompt this study. Outpatient TKA patients are often younger and have fewer comorbidities, but safety debates persist. Using a national database, we examined (1) trends in knee arthroplasty settings, (2) demographic differences, and (3) comorbidity variations to inform patient selection, outcomes, and policy.
We conducted a retrospective analysis using two national databases from 2019 to 2022. Adult patients undergoing elective, unilateral, primary TKA were identified using validated coding algorithms. We analyzed temporal trends in procedure location and compared demographic and comorbidity profiles between patients treated in hospitals versus outpatient facilities.
A total of 50% of the volume of primary TKA migrated to outpatient centers from 2019 to 2022. The proportion of hospital-based TKAs declined from 64 to 14%, while Ambulatory Surgical Center (ASC) based procedures rose from 36 to 86%. The ASC patients were younger (67.2 versus 67.6 years, P < 0.01), more likely to be White (78.6 versus 77.6%, P < 0.01), and more likely to have commercial insurance (P < 0.01). Hospital-based patients had significantly higher rates of nearly all comorbidities than those in outpatient facilities.
There has been a dramatic national migration of TKA procedures from inpatient hospitals to ASCs over the last four years. Patients selected for ASC-based TKA tend to be healthier and demographically distinct. These findings underscore the need for careful patient selection and ongoing evaluation of outcomes to ensure safety and equity in the delivery of outpatient TKA.