The Incidence of Thromboembolic Events in Surgically Treated Ankle Fracture

Background: Thromboembolic events occur following musculoskeletal injury, and some have serious sequelae, including death. The purpose of this study was to determine the incidence of thromboembolic events and its relationship with risk factors in ambulatory patients with ankle fracture requiring open reduction and internal fixation. Methods: We conducted a retrospective chart review of 2478 patients who underwent open reduction and internal fixation of an ankle fracture at any one of three university hospitals between January 1, 1997, and April 30, 2005. One thousand five hundred and forty patients meeting the inclusion criteria and with complete records (minimum follow-up, six months) were identified. The median age of the patients at the time of surgery was forty-six years, and there was an equal proportion of male and female patients. Fracture types included 45% unimalleolar fractures, 31% bimalleolar, and 24% trimalleolar. Charts were reviewed to identify thromboembolic events, risk factors (neoplasia, hormone use, pregnancy, blood dyscrasia, history of a previous thromboembolic event, a current history of smoking, obesity, dyslipidemia, atherosclerotic vascular disease, or paralysis), and use of thromboprophylactic agents. A thromboembolic event was defined as symptomatic when deep venous thrombosis was confirmed with use of Doppler ultrasonography or when pulmonary embolism was confirmed with use of ventilation and perfusion scintigraphy or helical computed tomography. Results: The incidence of thromboembolic events was 2.99% (forty-six patients), with 2.66% (forty-one patients) involving a deep venous thrombosis and 0.32% (five patients) involving a nonfatal pulmonary embolism. There were no fatal pulmonary emboli recorded. The incidence did not differ among hospitals. Of the 1540 patients, 16.43% received thromboprophylaxis during their hospital stay and for six weeks (for the 10.78% taking low-molecular-weight heparin) or three months (for the 5.65% taking warfarin) after discharge without significantly modifying the incidence of thromboembolic events (2.56% vs. 2.37%, relative risk = 0.91). However patients with one or more risk factors had a greater risk of a thromboembolic event than did patients with no risk factors (3.59% vs. 2.38%, respectively; relative risk = 0.66). The use of thromboprophylaxis had no apparent impact on the occurrence of thromboembolic events in patients who did or did not have risk factors (3.68% vs. 3.55%, respectively; relative risk = 0.96). No significant correlation could be identified between the occurrence of thromboembolic events and fracture types, age, or sex. Conclusions: Clinically detectable thromboembolic events after surgical treatment of ankle fractures are uncommon and do not appear to be influenced by the use of thromboprophylaxis. Patients with risk factors appear to be at higher risk for these events, but there is a need for prospective studies to determine the efficacy of thromboprophylaxis after surgical treatment of ankle fractures. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.