Background: Despite standard thromboprophylaxis, patients who sustain pelvic or acetabular (PA) fractures have a historically high venous thromboembolism (VTE) rate (12%). Thrombelastography (TEG) is a point-of-care analysis tool from which maximal amplitude (MA) values ≥65mm can quantify hypercoagulability and increased VTE risk in trauma patients.

Aims: (1) To utilize serial TEG analysis to define hypercoagulability duration following surgically treated PA fractures. (2) To compare MA values between patients with and without VTE.

Methods: After obtaining informed consent, consecutive adult patients with surgically treated PA fractures were enrolled from a single centre into this prospective cohort study with research ethics board approval. Serial whole-blood analysis was performed using a TEG6s hemostasis analyzer at timepoints determined a priori. Exclusion criteria: therapeutic anticoagulation, bleeding disorders, active malignancy, and pregnancy.

Patients received standardized thromboprophylaxis with prophylactic-dose low-molecular-weight heparin (LMWH) for 28 days post-operatively. VTE was defined as symptomatic pulmonary embolism (PE) or deep vein thrombosis (DVT), or asymptomatic proximal DVT from screening doppler ultrasound performed three days post-operatively. One-sided t-tests were used to compare the MA threshold (≥65mm) and serial MA measures, and MA values between patients with and without VTE (α=0.05).

Results: Thirty-three patients with a mean age of 47±19 years were included (10 females, 30%). The majority (96%) of patients were hypercoagulable at two weeks. 50% of patients remained hypercoagulable at the time of LMWH discontinuation, and 14% remained hypercoagulable at 3-months post-operatively. There were seven VTE events (21.2%) (Figure 1), including six symptomatic PEs. Mean MA for all VTE events over all timepoints closest to diagnosis was 68.2mm±4.8mm, while the overall mean for non-VTE was 64.0mm±7.1mm (p=0.06) (Table 1).

Conclusion(s): Prolonged hypercoagulability occurs in half of PA patients beyond discontinuation of standardized thromboprophylaxis. Serial TEG analysis warrants further study to help predict VTE risk and inform clinical recommendations for thromboprophylaxis duration following PA fractures.

Figure 1

Serial MA values, at each study timepoint, for each of the seven patients who suffered a VTE event -colours- compared with the mean of those patients who did not suffer a VTE event -black- with one standard deviation error bars. Horizontal dotted line indicates the ≥65mm threshold previously established to carry a nearly four-fold increased risk for in-hospital VTE in patients with major orthopaedic fractures, such as PA fractures.

Table 1

MA values at the timepoint closest to VTE diagnosis for the seven patients who had a VTE event, compared to the mean MA of all the individuals with no VTE, at the same timepoint.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/prolonged-hypercoagulability-occurs-following-pelvic-and-acetabular-fractures-as-defined-by-serial-thrombelastography/