Young adults who love to play outdoors and visit the clinic for hip pain are common. In our country, the most common causes of hip pain are ischemic necrosis of the femoral head, hip dysplasia, inflammatory diseases of the hip joint such as ankylosing spondylitis, and so on. However, some of these patients have insidious hip pain, slow onset and low hip deformity, which makes it difficult to diagnose a specific disease. Hip pain in adolescents should be prevented by hip impingement syndrome. Hip impingement syndrome, also known as femoroacetabular impingement syndrom (FAI), was first described in 2003 by Ganz et al. after Harris and colleagues observed about 50 years ago that mild abnormalities in hip morphology could lead to primary osteoarthritis. The cause may be dysplasia, femoral head necrosis, slipped femoral head, acetabular impingement, trauma, surgical overcorrection and a group of other causes of hip syndrome tilt. Hip impingement caused by excessive acetabular coverage is known as pincer impingement. The main factors are overcoverage, such as retroversion of the acetabulum, internal acetabular impingement, and internal acetabular protrusion. Acetabular dysplasia, slipped femoral epiphysis, trauma, and surgical overcorrection can lead to retroversion of the acetabulum, which is manifested as a “crossed sign” on the anterior and posterior acetabular margins on standard pelvic orthopantomographs. Main manifestations: history of hip pain or hip sprain. Most patients have unilateral onset, occasionally bilateral pain. Most of the patients complain of pain in the groin or deep hip pain, and some have pain in the front of the thigh and knee as the first symptom. The pain is usually vague in nature, with significant soreness and swelling. The pain is often felt when starting, and the pain and discomfort are obvious after walking long distances, but the walking distance on a flat road is not significantly limited. In some patients, the pain is triggered or aggravated during hip flexion such as squatting, bending, leg lifting, climbing, etc., and is accompanied by limitation of hip movement. Some patients have obvious joint flashing pain and joint interlocking symptoms, and some patients have different degrees of joint popping. The disease may lead to glenoid labral injury and cartilage damage in the corresponding part of the hip joint and develop into osteoarthritis at an advanced stage. Orthopedic examination: Most of the patients have normal hip mobility, some patients have different degrees of hip rotation restriction, among which internal rotation restriction is obvious, and patients may have hip pain when the hip is in extreme flexion and internal rotation or external rotation position, and positive hip 4-character test (pain or hip abduction and external rotation restriction), and some patients can palpate hip popping during hip flexion and extension. According to the clinicopathology, there are three types: pincer, cam, and mixed. Hip impingement caused by excessive acetabular coverage is called pincer impingement. Its main factors are overcoverage, such as posterior acetabular tilt, acetabular impingement, and acetabular protrusion. Acetabular hypoplasia, slipped femoral epiphysis, trauma, and surgical overcorrection can cause retroversion of the acetabulum, which can be seen as a “crossed sign” in the anterior-posterior border of the acetabulum on standard pelvic orthopantomographs. Hip impingement caused by lateral femoral neck augmentation is known as cam-type impingement. The main factor is the lack of eccentric distance at the femoral head-neck junction, such as an unrounded femoral head and hyperplasia of the head-neck junction area. The hyperplasia of the cephalocervical junction area caused by femoral head necrosis, slipped femoral head epiphysis, and flat hip makes the cephalocervical junction impingement with the outer upper edge of the acetabulum when the hip is flexed and internally rotated at the same time, and the bone fullness, protrusion, and cystic changes of the outer edge of the cephalocervical junction area can be seen on conventional frontal and lateral hip radiographs. On oblique films of direct MRI angiography of the hip through the femoral neck, an increased Alpha angle is demonstrated. The coexistence of the pincer and cam type is called mixed hip impingement. Most patients choose conservative treatment because the hip pain does not significantly affect their daily life and work. Conservative treatment includes avoiding heavy physical work, excessive exercise and long-distance walking, avoiding hip activities that cause pain, rehabilitation, acupuncture, massage, physical therapy, etc., taking non-steroidal painkillers and cartilage nutritional drugs when necessary, and regular review. If conservative treatment does not work, surgery is required. Surgical treatment can be divided into arthroscopic surgery and incisional surgery. The main goal is to remove the bony prominence of the acetabular rim and craniocervical junction, correct the glenoid lip and cartilage, remove the cause of impingement, and relieve symptoms. Patients with advanced osteoarthritis need to undergo artificial hip replacement surgery.