Background: Prolonged operative duration is an independent risk factor for postoperative complications in many orthopedic procedures ranging from shoulder arthroscopy to total hip and knee arthroplasties. It has not been well studied in unicompartmental knee arthroplasty (UKA). The purpose of this study is to assess the effect of operative duration on complications after UKA.

Methods: Using the American College of Surgeons National Surgical Quality Improvement Program registry, we identified all primary unilateral UKAs from 2005 to 18. Patients were divided into three cohorts based on the operative duration: < 90 minutes, between 90 and 120 minutes, and >120 minutes. Baseline patient and operative demographics (age, gender, etc.) and thirty-day complications were compared using bivariate analysis. Multivariate analysis was used to assess the independent effect of operative duration on postoperative outcomes after adjusting for differences in baseline characteristics.

Results: We identified 11,806 patients who underwent primary UKA from 2005 to 18. There was no difference in the "any complication" rate between cohorts. However, operative duration >120 minutes was associated with a significantly higher likelihood of reoperation (odds ratio [OR] 2.02, 95% confidence interval [CI]: 1.15-3.57, P = .015), non-home discharge (OR: 2.14, CI: 1.65-2.77, P < .001), surgical site infection (OR: 1.76, CI: 1.03-3.01, P = .038), and blood transfusions (OR: 3.23, CI: 1.44-7.22, P = .004) when compared with operative duration <90 minutes. There was no difference in mortality rates.

Conclusion: Increased operative duration greater than 2 hours in primary UKA is associated with an increased risk of non-home discharge, surgical site infection, reoperation, and blood transfusion.

Keywords: blood transfusion; complications; non–home discharge; operative duration; surgical site infections; unicompartmental knee arthroplasty.

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