The connection between the hip bone and the thigh is mostly referred to as hip joint popping, and the common causes are physiological phenomenon, bone fracture, hip impingement syndrome, hip synovitis, etc. The hip joint popping can occur when the air inside the hip joint is squeezed during the activity or when the muscle is tensed due to excessive exercise. 1. Physiological phenomenon: If the air inside the hip joint is squeezed during the activity or because of the muscle tension caused by excessive movement, the muscle slides on the femur big roughness during the activity, there can be a popping sound, which is a normal phenomenon. 2. Fracture: because of falling from a high place, car accident and other factors, resulting in femoral neck fracture, or the elderly have serious osteoporosis, even if there is no obvious trauma may also appear femoral neck fracture, fracture end friction with each other, there can be bone friction sound. 3. Hip impingement syndrome: because of the abnormal development of the hip joint, the head of the femur and the edge of the acetabulum collide, which can cause a popping sound, mostly accompanied by pain in the hip joint. 4. Hip synovitis: because of strenuous exercise, running, chronic strain and other factors, causing hip synovitis, which is a kind of aseptic inflammatory reaction. Common symptoms include hip joint pain, activity limitation, popping and so on. There are more causes of hip popping, and it may also be related to ankylosing spondylitis and other diseases. If the symptoms continue to be unrelieved, it is recommended to consult a doctor in time to clarify the cause of the disease and carry out targeted treatment.