A 28-year-old male labourer presents to the emergency department 2 hours after a heavy wooden beam fell on his right leg. On examination, there is severe swelling, ecchymosis, and deformity of the mid-shaft region. The limb is cold and pale distal to the injury site, with absent dorsalis pedis pulse. Plain radiographs show a comminuted fracture of the femur with displacement. What is the most appropriate immediate next step in management?