Same-Day Total Joint Arthroplasty in the United States From 2016 to 2020: The Impact of the Medicare Inpatient Only List and the COVID-19 Pandemic.

Background: Same-day total hip arthroplasty (THA) and total knee arthroplasty (TKA) continue to gain popularity in the United States. The present study sought to quantify recent same-day outpatient trends taking into consideration the COVID-19 pandemic as well as the removal of these procedures from the Medicare inpatient only (IPO) list.

Methods: Patients undergoing primary elective TKA and THA were identified using the Nationwide Ambulatory Surgery Sample and the National Inpatient Sample from January 1, 2016, to December 31, 2020. The same-day cohort included Nationwide Ambulatory Surgery Sample and National Inpatient Sample patients with a length of stay = 0 days. The inpatient cohort included patients with length of stay ≥1 day. National estimates were extrapolated using weight functions.

Results: From January 2016 to December 2020, the proportion of same-day TKA increased from 1.2 (719) to 62.4% (31,293) and the proportion of same-day THA increased from 2.0 (599) to 54.5% (18,252). Following removal from the Medicare IPO list, same-day TKAs increased from 3.2% (1,895) in December 2017 to 13.8% (9,269) in January 2018, and same-day THAs increased from 10.7% (4,295) in December 2019 to 22.5% (8,708) in January 2020. Between February and March 2020, same-day TKAs increased from 42.4 (26,148) to 44.4% (16,972) and same-day THAs increased from 28.5 (10,729) to 30.2% (7,409).

Conclusions: The proportion of same-day TKA and THA dramatically increased following removal from the Medicare IPO list and in response to the COVID-19 pandemic. By December 2020, same-day TKA and THA accounted for >50% of all cases performed in the United States.