Prognostic Risk Factors for Complications Associated with Below the Knee Amputations

Abstract

Category: Other Introduction/Purpose: Below the knee amputation (BKA) is an effective surgical procedure for individuals with severe injury or infection to their lower extremities. However, patients who receive these procedures are subject to significant morbidity and a high rate of postoperative complications due to the presence of multiple concomitant comorbidities. Despite the wide practice of this intervention, prognostic risk factors aiding in predicting surgical outcomes in these patients are poorly understood. The purpose of this study is to evaluate risk factors that may contribute to the outcomes of BKA procedures. Methods: The clinical and radiographic outcomes for 89 patients ages 19-90 who underwent BKA were retrospectively evaluated from 2012-2017. Postoperative complications of mortality, infection, and reoperation were evaluated with patient and surgical variables. Patient variables included: age, ambulatory status, obesity, diabetes, HbA1C2 levels, neuropathy, smoking, Charlson Comorbidity Index (CCI), and American Society of Anesthesiologists (ASA) classification. Surgical variables evaluated included: presence of pre-op infection, pre-op ambulatory status, tourniquet time, tourniquet pressure, and usage of prophylactic antibiotics. Results: Of the patients evaluated there was an overall complication rate of 49% (44/89) and a mortality rate of 19% (17/89). Patients with diabetes (p=.035), a greater score on the Charlson Comorbidity Index (p=.001), and an ASA classification =3 (p=.005) were associated with a greater risk of mortality. Operative values (i.e. tourniquet time, tourniquet pressure etc.) did not affect patient mortality rates in a significant way, but there was a higher incidence of complications (i.e. mortality, post-op infections, and reoperations) with patients with pre-operative infections. Conclusion: Diabetes, a higher CCI score and a greater ASA value were found to be significant predictors of patient mortality after BKA (p<0.05). Future perioperative optimization in these patients identified as high risk may improve patient outcomes in the future.