A snapping hip is an audible or perceptible ringing sound when the hip joint is actively extended and flexed and when walking. There are many reasons for popping, among which lateral factors are more common. The main reason for this is the thickening of the posterior edge of the iliotibial bundle or the anterior edge of the gluteus maximus tendon. When the hip joint is flexed, internally retracted or internally rotated, the thickened tissues slide back and forth in the greater trochanter and emit a popping sound. This phenomenon does not occur during passive movement, and is usually seen in young adults, often bilaterally. Fibrosis of the posterior gluteus maximus muscle caused by multiple intramuscular injections can also cause popping and requires surgical treatment. The snapping caused by structural disorders of the lateral hip rarely requires surgery because it does not cause pain. Patients are often reluctant to undergo treatment once the cause is understood. If there is pain, first of all, conservative treatment should be taken as far as possible to control the symptoms, such as physiotherapy, local injection or change the movement habits, which generally has a good effect. 2, hip joint medial factor The hip can be caused by the structural disorder of the iliopsoas tendon or its subacromial bursa. When the hip is flexed, the iliopsoas tendon moves to the outside of the center of the femoral head, while when the hip is extended, the tendon slips over the femoral head to the inside, and this back and forth movement of the iliopsoas tendon on the femoral head can produce a popping sound. This back and forth movement of the iliopsoas tendon over the femoral head can also produce a popping sound. The iliopsoas muscle slides over the iliopubic crest eminence or the small ridge of exophytic bone. The same popping symptom occurs when the tendon crosses the bursa of the iliopsoas muscle that rises between the tendon and the anterior part of the hip capsule. Bursography of the iliopsoas muscle has been shown to be the most useful radiological test for identifying the cause of medial hip popping. For such patients, MRI can effectively exclude intra-articular lesions. 3, intra-articular factors The snapping sensation that can be felt by both the patient and the physician can sometimes be caused by intra-articular disorders, such as osteochondromatosis, other free bodies, injury to the glenoid labrum of the acetabulum, or hip subluxation secondary to abnormalities of the posterior border of the acetabulum or paralysis of the hip muscles. Habitual dislocation or subluxation of the hip in children and young adults is also a cause of a rattling hip.