en پا و مچ پا Foot and Ankle پژوهشی Research Article <div style="text-align: justify;"><strong>Background:</strong> The incidence of Venous Thromboembolism (VTE) and its prophylaxis in patients with an ankle injury and cast immobilization are controversial.<br> <strong>Objectives:</strong> This study aimed to investigate the effect of aspirin and enoxaparin on VTE prevention in patients with an ankle sprain and cast immobilization.<br> <strong>Methods: </strong>In a double-blind, randomized clinical trial, 90 eligible patients were divided into three groups: patients who did not receive the drugs (the control group), patients who received aspirin (325 mg/d) for 3 weeks (the ASA group), and patients who received enoxaparin (40 mg/d subcutaneously) for 3 weeks (the enoxaparin group). After 3 weeks, the plaster was opened, and the D-dimer level was measured if there was a VTE symptom during the study. Otherwise, at the end of the study, the bilateral lower-limb Complete Compression Ultrasonography (CCUS) and color Doppler ultrasound were used to image the lower limb venous system.<br> <strong>Results:</strong> Sixty-eight patients completed the study. The mean&plusmn;SD values of D-dimer in the control, ASA, and enoxaparin groups were 0.33 (0.47) &mu;g/dL (Median=0.18 &mu;g/dL), 0.32 (0.14) &mu;g/dL (Median=0.3 &mu;g/dL) and 0.32 (0.25) &mu;g/dL (Median=0.21 &mu;g/dL), respectively (P>0.05). The positive D-dimer was seen in 2 patients (8%) of the control group, 2 patients (8.3%) of the ASA group, and 2 patients (10.5%) of the enoxaparin group (P>0.05). The color Doppler ultrasound was negative in all patients.<br> <strong>Conclusion:</strong> Because none of the 68 patients in the current study developed VTE during our 30 days follow-up period, it seems that prophylaxis treatment is unnecessary in patients with an ankle sprain and cast immobilization. Further studies on more patients with a longer period of follow-up are recommended.<u><span dir="RTL"></span></u></div> Ankle sprains, Venous thromboembolism, Immobilization, Aspirin, Enoxaparin 9 16 http://jros.iums.ac.ir/browse.php?a_code=A-10-703-2&slc_lang=en&sid=1 Mehran Razavipour 10031947532846004256 10031947532846004256 No Department of Orthopedics, Orthopedic Research Center, Mazandaran University of Medical Sciences, Sari, Iran. Salman Ghaffari 10031947532846004257 10031947532846004257 No Department of Orthopedics, Orthopedic Research Center, Mazandaran University of Medical Sciences, Sari, Iran. Mehdi Mohebi 10031947532846004258 10031947532846004258 No Department of Orthopedics, Orthopedic Research Center, Mazandaran University of Medical Sciences, Sari, Iran. Shayan Amjadi 10031947532846004259 10031947532846004259 Yes Department of Orthopedics, Orthopedic Research Center, Mazandaran University of Medical Sciences, Sari, Iran.