The MangLE score: A novel simple tool to identify patients who are unlikely to require amputation following severe lower extremity injury

BACKGROUND There are no validated and sensitive models that can guide the decision regarding amputation in patients with mangled lower extremities. We sought to describe a simple scoring model, the Mangled Lower Extremity (MangLE) score, which can predict those who are highly unlikely to need an amputation as a means to direct resources to this cohort. METHODS This is a retrospective study using the 2013–2021 American College of Surgeons Trauma Quality Improvement Program data set. Adult patients with a mangled lower extremity, defined as a crush injury or a fracture of the femur or tibia combined with severe soft tissue injury, arterial injury, or nerve injury, were included. Patients who suffered a traumatic lower extremity amputation, underwent amputation within 24 hours of admission, or who died within 24 hours of admission were excluded. Patients were divided into those who did/did not undergo amputation during their hospital stay. Demographics, injury mechanism, Injury Severity Score, and Abbreviated Injury Scale score, initial vital signs, and comorbid conditions were abstracted. A logistic regression model was constructed and the top five most important variables were used to create the score. RESULTS The study includes 107,620 patients, of whom 2,711 (2.5%) underwent amputation. The five variables with the highest predictive value for amputation were arterial injury, lower-extremity Abbreviated Injury Scale score of ≥3, crush injury, blunt mechanism, and shock index. The lowest possible MangLE score was 0, and the highest was 15. The model demonstrated an excellent predictive ability for lower extremity amputation in both the development and validation data set with an area under the receiver operating characteristic curve of 0.81 (95% confidence interval, 0.80–0.82) and 0.82 (95% confidence interval, 0.81–0.84), respectively. The negative predictive value for a score of <8 is 99%. CONCLUSION The MangLE score is able to identify patients who are unlikely to require amputation. Resources for limb salvage can be directed to this cohort. LEVEL OF EVIDENCE Prognostic and Epidemiological; Level IV.