Thigh root sometimes pain sometimes no pain, common causes are as follows: first, hip joint impingement syndrome, hip joint femoral neck development abnormality, resulting in femoral neck osteophytes. When the hip joint carries out flexion, extension and rotation activities, the femoral neck and the acetabular labrum undergoes abrasion and impingement, resulting in damage to the labrum cartilage and causing pain in the hip joint. There is no obvious pain when walking normally, but when the hip joint is over flexed and rotated, pain symptoms appear. Second, aseptic necrosis of the femoral head, ischemia of the femoral head can cause aseptic necrosis, in the process of necrosis of the femoral head, it can be accompanied by symptoms of joint pain. The pain is intermittent, and when the disease progresses to the advanced stage, it is manifested as persistent pain in the hip joint.