Risk of complications with prolonged operative time in morbidly obese patients undergoing elective total knee arthroplasty.

Background: Patients with a high body-mass index (BMI) are at increased risk for significant complications after total knee arthroplasty (TKA). We explored whether operative time is a modifiable risk factor for infectious and thromboembolic complications.

Methods: A retrospective observational cohort study of the ACS-NSQIP registry, including all patients who underwent primary TKA (2015-2018), and were morbidly obese (BMI 40 kg/m or greater) was performed. We created four categories of operative time in minutes: less than 60, 60-90, 91-120, and greater than 120. The association of prolonged operative time with superficial/deep surgical site infection (SSI), DVT and PE within 30 days postoperatively was evaluated using multivariate logistic regression.

Results: 34,190 patients were included (median age 63 [IQR 57-68], mean BMI of 44.6 kg/m [SD 4.4]). The majority of patients had an operative time between 60-90 mins (n = 13,640, 39.9%) or 91-120 mins (n = 9908, 29.0%). There was no significant association between longer operative time and superficial/deep/organ-space SSI or PE. DVT risk was significantly increased. Patients with time exceeding 120 mins had nearly 2.5 greater odds of DVT compared to less than 60 minutes (OR 2.47, 95% CI: 1.39-4.39, P = 0.002). Odds of DVT were 1.73 times greater in those with time of 91-120 mins (OR 1.73, 95%CI: 0.98-3.05, P = 0.06).

Conclusion: Early infection and thromboembolic complications with prolonged operative time in morbidly obese patients remain low. We did not identify a significant association with increased operative time and superficial/deep SSI, or PE. There was a significantly increased risk for deep vein thrombosis with prolonged operative time.