Risk factors for reoperation, readmission, and early complications after below knee amputation

Background: Many patients undergoing below knee amputations (BKA) return for subsequent unplanned operations, hospital readmission, or postoperative complications. This unplanned medical management negatively impacts both patient outcomes and our healthcare system. This study primarily investigates the risk factors for unplanned reoperation following BKA.

Methods: Below knee amputations from the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database from the years 2012-2014 were identified by CPT code 27880 for amputation through the tibia and fibula. Our query identified 4631 BKA cases, including 30 day complications. Multivariate logistic regression modeling was performed on several patient demographic and disease factors to assess for independent predictors of unplanned reoperation. Secondary outcomes of unplanned and related readmissions (related to the procedure), major complications, minor complications, and mortality were also included in the analysis.

Results: Of 4631 BKAs identified, 9.63% (446/4631) underwent unplanned reoperations and 8.75% (405/4631) had unplanned and related readmissions. Major complications were experienced by 12.8% (593/4631) and minor complications by 8.7% (401/4631). Thirty day mortality rate was 5.14% (238/4631). The most common procedures for unplanned operations were thigh amputations (128/446, 28.7%), debridement/secondary closure (114/446, 25.6%), and revision leg amputations (46/446, 10.32%). Factors associated with an increased risk of unplanned reoperation included patients transferred from another facility (Adjusted Odds Ratio [AOR] = 1.28; p = .04), recent smokers (AOR = 1.34; p = .02), bleeding disorder (AOR = 1.30; p = .02), and preoperative ventilator use (AOR = 2.38; p = .01).

Conclusion: Patients that were ongoing/recent smokers, had diagnosed bleeding disorders, required preoperative ventilator use, or were transferred in from another facility were associated with the highest risks of reoperation following BKA. This patient population experiences high rates of reoperation, readmission, complication, and mortality.