BackgroundTotal joint arthroplasty is shifting from hospitals to ambulatory surgery centers (ASCs) and hospital outpatient departments (HOPDs). A Michigan Arthroplasty Registry Quality Collaborative Initiative quality improvement project examined readmissions, emergency room (ER) visits, periprosthetic joint infection (PJI), fracture, and dislocation after primary total hip arthroplasty (THA) or total knee arthroplasty (TKA) across sites.MethodsPrimary TJAs between July 1, 2021, and June 30, 2022 (N = 41,696: 3910 ASC, 1,834 HOPD, and 35,952 hospital) were reviewed. Of 17,100 THAs, 9.5% (1,631) were at ASCs, 4.7% (798) at HOPDs, and 85.8% (14,671) at hospitals. Of 24,596 TKAs, 9.3% (2,279) were at ASC, 4.2% (1,036) at HOPDs, and 86.5% (21,281) at hospitals. Hospitals treated more elderly, women, non-White, obese, diabetics, smokers, and governmental insurance.ResultsFor THAs, ASCs had the lowest 30-day (ASC 1%, HOPD 1.8%, hospital 3.4%, P < .001) and 90-day (ASC 1.7%, HOPD 3.4%, hospital 5.5%, P < .001) readmissions, 30-day ER visits (ASC 1.8%, HOPD 3.5%, hospital 5.3%, P < .001), and fractures (ASC 0.4%, HOPD 0.6%, hospital 1.2%, P < .001). Similar trends were observed for TKAs: 30-day readmissions (ASC 1.3%, HOPD 1.4%, hospital 3.1%, P < .001), 90-day readmissions (ASC 2.2%, HOPD 2.3%, hospital 5.2%, P < .001), and 30-day ER visits (ASC 3%, HOPD 6.5%, hospital 6.4%, P < .001). PJI (THA: P = .1, TKA: P = .6) and dislocation rates (P = .5) were similar across sites.ConclusionsPatients receiving primary total joint arthroplasty at an ASC had the least postoperative hospital-based care despite similar rates of PJI and dislocation.