saem a 22 year old running back is struck from behind by a 300-pound lineman. the blow occurs below the knee as his foot is firmly planted and two other lineman are holding his upper body. he presents to the emergency department with gross anterior dislocation of the tibia on the femur. his foot is cool and palee, and dorsalis pedis and posterior tibial pulses are not detected by doppler ultrasound. what is the most appropriate management for this patient?