The Journal of Arthroplasty, Volume 32, Issue 6, 1773 - 1778

Comparison of Outpatient vs Inpatient Total Knee Arthroplasty: An ACS-NSQIP Analysis

Bovonratwet, Patawut et al.


There has been a recent surge of interest in performing primary total knee arthroplasty (TKA) in the outpatient setting to reduce cost and increase patient satisfaction. Detailed information on the safety of outpatient TKA in large sample sizes is scarce.


Patients who underwent primary, elective TKA were identified in the 2005-2014 American College of Surgeons National Surgical Quality Improvement Program database. Outpatient procedure was defined as having a hospital length of stay of 0 days, whereas inpatient procedure was defined as having a length of stay ≥1 days. To reduce the effect of confounding factors and nonrandom assignment of treatment, propensity score matching was used. Multivariate analyses on the matched samples were used to compare the rates of adverse events that happened any time during the 30-day postoperative period, postdischarge adverse events, and readmissions between the outpatient and inpatient cohorts.


A total of 112,922 TKA patients met the inclusion criteria. Of these, only 642 (0.57%) were outpatient procedures. Outpatients tended to be men, slightly younger, and have less comorbidity. After propensity matching, multivariate analysis revealed a higher rate of postdischarge blood transfusions (P < .001) in the outpatient cohort. There were no other significant differences in 30-day postoperative individual adverse events or readmissions.


Based on the perioperative outcome measures studied here, outpatient TKA can be appropriately considered in select patients based on rates of overall perioperative adverse events and readmissions. However, higher surveillance of these patients postdischarge may be warranted.

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