Sciatic nerve palsy may occur in the following injury

Sciatic nerve injury - following posterior dislocation of hip. 3 times more common in fracture dislocation than simple dislocation. It is usually a neuropraxia & the peroneal division is commonly affected. It may be due to stretch of the nerve or may be due to impalement between fracture fragments. If it is associated with acetabular fracture nerve should be explored, the prognosis is variable. *sciatic nerve may be injured by penetrating wound , fracture of pelvis, misplaced therapeutic injection in the gluteal region ( most common cause) * motor loss : inability to extend the thigh & flex the knee , due to paralysis of hamstring muscles - loss of all movements below knee with foot drop,due to paralysis of all muscle of leg & foot - motor lossless to flail the foot & severe difficulty in walking ,walks with high stepping gait * sensory loss : back of thigh & whole of leg & foot except area innervated by saphenous nerve due to involvement of cutaneous nerve derived from tibial & common peroneal REF:Textbook of Ohopedics, John Ebenezer, 4th edition, page no 219