A 52-year-old man from Delhi presents to the emergency department with acute onset severe pain in the left buttock and posterior thigh, radiating down to the foot, following a fall onto his left hip. On examination, he has weakness of hip extension and knee flexion, with diminished sensation over the lateral leg and dorsum of foot. An X-ray shows a posterior hip dislocation with an associated sciatic nerve injury. After initial stabilization and reduction of the dislocation, what is the most appropriate next step in management of the nerve injury?