Causes of drug injection injury, especially injection of penicillin, is the most common cause of sciatic nerve injury, also known as medically induced sciatic nerve injury, which occurs in children, the cause of injury and injection site improper direct injury or too large a dose of drugs to stimulate the sciatic nerve; sharp force injury, acetabular fracture, pelvic fracture and hip dislocation, especially posterior dislocation is also a common cause of sciatic nerve injury. Diagnosis 1. Movement: If the injury site is at the sciatic foramen or above the sciatic tuberosity, the posterior femoral muscles, the anterior, lateral and posterior calf muscles and the foot muscles are all paralyzed. If the injury is in the middle and lower femur, because the popliteus muscle branch has been mostly emitted, only the muscles below the knee are paralyzed. If the injury is to its branches, the muscles of the innervated areas of the common peroneal nerve and tibial nerve will be paralyzed respectively. 2. Sensation: Except for the saphenous nerve innervation area at the medial calf and inner ankle, the sensation in the area below the knee is lost. 3.Nutrition: There are often severe nutritional changes, and there are often deep ulcers on the bottom of the foot. History of trauma or injection, paralysis of muscles below the thigh or below the knee; paralysis of muscles in the area innervated by nerve branches. Partial loss of sensation in the area below the lower leg. Electromyography may confirm the diagnosis.