Research Summary

Outpatient Knee Arthroplasty Linked to Fewer 30-Day Complications Than Inpatient Procedures, Even Post-COVID

Kate Young

Key Highlights

  • Outpatient total knee arthroplasty (oTKA) had significantly fewer 30-day adverse events compared with inpatient TKA (iTKA).
  • This trend remained consistent both before and after the COVID-19 pandemic.
  • Postoperative transfusions were less frequent in oTKA patients across all years.
  • Age, BMI, and chronic obstructive pulmonary disease were identified as risk factors for adverse events.

Outpatient total knee arthroplasty (oTKA) was associated with significantly fewer 30-day adverse events compared with inpatient procedures (iTKA), a trend that held steady across both pre- and post-COVID-19 periods. These findings suggest that the increasing adoption of oTKA—even in the wake of the pandemic—did not compromise patient safety and may offer a safer short-term profile than traditional inpatient care.

This study addresses the growing shift toward outpatient TKA, driven by evolving health policy and the impact of the COVID-19 pandemic. As more procedures transition to outpatient settings, understanding whether this impacts patient outcomes is crucial to guide clinical decisions and inform best practices.

Researchers used a national database to identify 533,503 patients who underwent primary TKA between 2008 and 2021. They used Current Procedural Terminology codes and applied propensity score matching to control for demographic and comorbidity differences. They then analyzed 30-day postoperative complication rates and evaluated risk factors for adverse outcomes.

Of the total cohort, 31,905 patients (6.0%) underwent oTKA and 501,598 (94.0%) underwent iTKA. The rate of any adverse event (AAE) remained significantly lower in those who underwent oTKA throughout the study period (P < .001). This finding persisted in both pre-COVID (2008–2019) and post-COVID (2020–2021) analyses (P = .001 and P = .004, respectively). Notably, postoperative transfusions occurred less frequently in oTKA cases across all years and were further reduced in post-pandemic oTKA cases (P = .027). Outpatient setting consistently emerged as a protective factor against adverse events, while increased age, BMI, and a history of COPD elevated risk.

“Despite a rapid increase in the utilization of oTKA after the onset of the COVID-19 pandemic, 30-day adverse events did not increase and remained lower than that of iTKAs overall,” the study authors concluded.

Reference:
Sandoval LA, Reiter CR, Wyatt PB, et al. Outpatient total knee arthroplasty has become more frequent since the onset of the COVID-19 pandemic without an increase in early post-operative complications. J Arthroplasty. 2025;40(8):1992-2000.e2. doi:10.1016/j.arth.2025.01.036