Paralysis of muscles below the thigh or below the knee is commonly associated with sciatic nerve injury. Diagnosis of sciatic nerve injury: history of trauma or injections, paralysis of muscles below the thigh or knee; paralysis of muscles in the innervated area of the nerve branches. Partial loss of sensation in the area below the calf. Electromyography confirms the diagnosis. Examination of paralysis of muscles below the thigh or below the knee: 1. Movement: if the injury site is at the sciatic foramen magnum or above the sciatic tuberosity, the posterior femoral muscle group, the anterior, lateral, and posterior calf muscle groups, and all the muscles of the foot are paralyzed. If the injury is in the middle and lower part of the femur, the muscles below the knee will be paralyzed because the branch of the naevus muscle has been issued in large part. If the branch is injured, the muscles in the innervation area of the common peroneal nerve and tibial nerve are paralyzed. Sensation: Except for the saphenous nerve innervation area at the medial side of the calf and the inner ankle, sensation is lost in the area below the knee. 3.Nutrition: There are often severe nutritional changes, and deeper ulcers are often found on the soles of the feet. 4.History of trauma or injection: paralysis of the muscles below the thigh or below the knee, and paralysis of the muscles in the innervated area of the nerve branches. Partial sensory loss in the area below the calf. Electromyography can confirm the diagnosis.