Currently, Enoxaparin is the usual prophylactic anticoagulant treatment at the acute and sub-acute phases of spinal cord injury (SCI). Patients at the sub-acute phase of SCI (rehabilitation) will be given either Enoxaparin 40 mg/day (control) or Apixaban 2.5-5 mg twice a day. Apixaban dose will be determined by the treating physician. Treatment will be continued for either 6 or 12 weeks following injury (for AIS grades C-D and A-B respectively). Endpoints: Venous thromboembolism will be evaluated by D-Dimer test every 2 weeks and an ultrasound doppler at the beginning and the end of the treatment. Bleeding events will be recorded and hematocrit will be monitored every two weeks.