Incidence and safety profile of outpatient unicompartmental knee arthroplasty

Abstract

Background: Outpatient surgery is an increasingly attractive option for patients undergoing procedures with established, acceptable risk profiles. Benefits of outpatient surgery include cost savings, enhanced patient experience and improved resource allocation at busy hospitals. The purpose of this study was to compare 90-day complication and readmission rates for patients undergoing unicompartmental knee arthroplasty (UKA) in the outpatient as opposed to the inpatient setting.

Methods: Patients who underwent UKA (CPT code 27446) between 2007 and 2016 were retrospectively selected from a national private insurance database. Patients were defined as ambulatory if their coded location of procedure was in an ambulatory surgery center or as an in-hospital outpatient. Postoperative complications were identified using the Reportable Center for Medicare Services (CMS) Complication Measures. Risks of complications were compared between the inpatient and outpatient cohorts using multivariate logistic regression controlling for age, gender, and comorbidities.

Results: 2600 patients undergoing ambulatory UKA and 5084 patients undergoing inpatient UKA were identified. The percentage of UKA procedures performed on an outpatient basis significantly increased over the course of the study (14.5% to 58.1%, p < 0.001). After adjusting for age, gender, and comorbidities, ambulatory surgery was found to be associated with a decreased risk of postoperative transfusion (OR 0.28; p < 0.001) and pneumonia (OR 0.23; p = 0.008) and there was a trend towards decreased 90-day readmission risk (OR = 0.83; p = 0.062).

Conclusion: Ambulatory discharge following UKA is increasing in popularity, does not increase risk for perioperative complications or readmission, and may even portend a safer post-operative course.

Keywords: Complications; Medial; Outpatient surgery; Readmission; Unicompartmental knee arthroplasty.