In clinical practice, the phenomenon of numbness at the root of the thigh often occurs, and this symptom can be caused by many clinical reasons. If the patient is suffering from femoral head necrosis, the patient will first feel pain and numbness at the root of the thigh, positive pressure pain, positive percussion pain, positive 4-character test on clinical examination, and the pain and numbness at the root of the thigh will increase when the patient is bearing weight. The degree of femoral head necrosis can be clearly diagnosed by taking an X-ray or CT film of the hip. In addition, if the soft tissue at the root of the thigh is damaged due to prolonged excessive activity, localized numbness and weakness may also occur. If a patient has a severe lumbar disc herniation, resulting in compression of the dural sac and numbness and weakness at the root of the thigh, a CT film of the lumbar spine can be taken to make a clear diagnosis.