ABNORMAL PREOPERATIVE CLOT PROPAGATION PARAMETERS FROM THROMBELASTOGRAPHY MAY IDENTIFY PATIENTS WITH FEMUR FRACTURES AT HIGHEST RISK FOR VENOUS THROMBOEMBOLISM

Despite the use of thromboprophylaxis, the risk for venous thromboembolism (VTE) after surgical fixation of femur fractures remains high (minimum of 2.1%). The optimal duration of thromboprophylaxis remains unclear, with extrapolation of hip fracture guideline recommendations suggesting a minimum of 10-14 days, while the duration of hypercoagulability and increased VTE risk remains unknown. Thrombelastography (TEG) is a whole-blood viscoelastic hemostatic assay which provides a comprehensive real-time analysis of hemostasis, from clot initiation to fibrinolysis. Therefore, TEG analysis may provide valuable information on the coagulation kinetics responsible for hypercoagulability to guide thromboprophylaxis regimens. The aims of this study were to determine the different phases of coagulation responsible for hypercoagulability and to quantify the duration of hypercoagulability that ensues for patients requiring urgent femur fracture fixation. This is a single center prospective cohort study of consecutive patients requiring femur fracture fixation. Eligible participants who provided informed or surrogate consent underwent serial TEG analysis every 24-hours from admission until post-operative day (POD) 4, then at 2-, 4-, and 6-week post-operative follow-up. All blood samples were analyzed using a TEG®6s Hemostasis Analyzer (Haemonetics Corp). Hypercoagulability was defined as a maximal amplitude (MA) of 65mm or greater, where MA is a measure of platelet contribution to maximal clot strength). Patients who remained in the hospital underwent screening doppler ultrasound on POD3 to evaluate proximal deep vein thrombosis (DVT). One-sample t-tests were used to compare MA values to the hypercoagulability threshold at each timepoint. Wilcoxon signed-rank tests were used to compare TEG parameters at each timepoint to the admission values. Paired samples t-tests or Mann-Whitney U tests were used to compare TEG parameters between those with and without VTE events. In total, 85 patients with a mean age of 45.1 (SD = 20.1) years were included, with 62.5% being male. The MA values peaked two weeks post-operatively (mean MA=70.4, SD=4.5; p). Serial TEG analysis was able to quantify a prolonged platelet-dominant hypercoagulability which extended beyond current recommended thromboprophylaxis duration after femur fracture surgery, supporting that extended thromboprophylaxis with antiplatelet agents may be beneficial. Pre-operative clot propagation parameters from TEG analysis (alpha-angle and k-time) were abnormal and MA was additionally elevated at the time of VTE in patients who suffered VTE. This novel data may help identify the highest risk patients prior to femur fracture fixation.