The cause of thigh root pain can not lift the leg is divided into physiological and pathological, the former is mainly seen after strenuous exercise, the latter can be seen in the lumbar spine disease, osteoarthritis of the hip joint, pear-shaped muscle syndrome. 1. Physiological: after strenuous exercise or heavy physical strength, due to the accumulation of excessive local lactic acid can not be excreted in a timely manner, resulting in soreness at the root of the thigh. 2.Pathologic (1) Lumbar spine disease: such as lumbar disc herniation, spinal stenosis and other compression of nerves, causing radiating thigh root pain. (2) Osteoarthritis of hip joint: the pain of this disease is often accompanied by claudication, and the site of general pain can be in front of the hip joint, lateral or inner thigh. (3) Piriformis syndrome: it manifests as obvious pressure pain in the area of the piriformis muscle of the hip, and radiates to the posterior and medial thighs, as well as the posterior and lateral calves. In addition to the above reasons, femoral head necrosis can also cause thigh root pain and swelling and inability to lift the leg. It is recommended to go to the hospital in time, complete the examination to clarify the cause of the disease, and then give targeted treatment or therapy.