Complications Associated with Administration of Post-operative Weight-Based Enoxaparin in Orthopaedic Trauma Patients

Background In orthopedic-specific patients, limited evidence exists in regard to prophylactic weight-based enoxaparin dosing in the obese population. We examined the clinical outcomes of administering weight-based enoxaparin to obese orthopedic trauma patients. Methods This retrospective study involved 679 patients who underwent orthopedic trauma surgery and were admitted from 1/2016 to 6/2020 at a single institution. Of those patients, 156 patients met our inclusion criteria. Inclusion criteria included BMI>35 kg/m² and received weight-based enoxaparin post-operatively (defined as any singular dose >40 mg at any time). Blood transfusion, documented hematoma, deep vein thrombosis (DVT), and return visits to the OR after the administration of weight-based enoxaparin were the primary endpoints assessed. Age, BMI, weight, injury severity score (ISS), sex, post-operative time to the first dose of enoxaparin, the total daily dose of enoxaparin, operating room (OR) blood loss, OR time, patient co-morbidities, and pre/post-operative hemoglobin were evaluated for a potential relationship with the primary endpoints. Results One hundred and eighty-five surgeries were performed on a total of 156 patients. Thirty-six of the 185 (19%) surgeries required post-operative blood transfusion after weight-based enoxaparin was given. Higher ISS score, lower pre-operative hemoglobin, and lower post-operative hemoglobin were significant predictors of blood transfusion. Only increased post-operative time to the first dose of enoxaparin was significantly associated with DVT formation. Thirteen of the 156 patients (8.3%) had a post-operative hematoma after administration of enoxaparin, and four of the 13 patients required return to the OR for bleeding complications. ISS was the only significant predictor of post-operative hematoma formation. Conclusion Patients with a higher injury severity score are at an increased risk of adverse bleeding and may benefit from lower doses of enoxaparin administered earlier post-operatively.