Developmental dysplasia of the hip (DDH), formerly known as congenital dislocation of the hip (CDH), is a developmental abnormality of the hip joint that occurs at birth and continues to deteriorate after birth. The main manifestation is an abnormality in the matching and accommodating relationship between the acetabulum and the femoral head. The pain and deformity of the hip joint usually become more serious when the symptoms appear in adulthood, and surgery is often required to improve the quality of life. Clinical manifestations and secondary manifestations 1, adult DDH is mostly seen in women, usually between the ages of 20 and 40 years old with obvious hip symptoms, some patients can also be asymptomatic for life and not be detected. 2.In the early stage, the main manifestation is fatigue, soreness and vague pain in the affected hip joint, but it can also occur in other areas, such as the groin area, front of the thigh and hip. Local pressure pain, percussion pain and rotation pain in the hip joint, with normal mobility. 3, The clinical symptoms in the middle and late stages are mainly increased hip pain, followed by claudication, rest pain, hip subluxation or total dislocation and limb shortening deformity, with the gradual aggravation of osteoarthritis leading to different degrees of limitation of hip joint activities. 4, A few patients have no symptoms and are found by chance when taking X-rays. 5.Hip dysplasia or dislocation will lead to change of body center of gravity and lower limb force line and limb unequal length, which will cause lower back pain. Correcting hip dislocation, stabilizing the hip joint and improving the unequal length of both lower limbs can improve and relieve the lumbar symptoms and delay the progress of lumbar spine osteoarthritis. 6, for patients with unilateral DDH, in order to avoid the continuous aggravation of lumbar symptoms, resulting in serious irreversible spinal deformation, total hip arthroplasty should be performed as soon as possible. Misconception 1, hip joint “aging”: Adult DDH usually produces symptoms around the age of 40, many people mistake hip pain for hip joint “aging” and think that it will improve with some drugs. This is due to the lack of understanding of the early onset of DDH, because the anatomical characteristics of the hip joint determine the direction of onset of DDH patients and ordinary hip degeneration is not the same, many times only through surgery to solve the problem. 2, delay may be good: reduce the activity and use of drug therapy for early adult DDH hip symptoms have obvious relief, so some patients will have a certain fluke mentality “delay may be good”. In fact, in addition to the bony structure of the adult DDH hip, soft tissue problems may arise as the disease progresses, which may also lead to osteoarthritis of the opposite hip and bilateral knee joints due to stress factors. At the same time, some patients have problems with the lumbar spine because of the pelvic tilt, so delaying the problem often leads to more “trouble”. 3. Can a decades-old problem be cured? Many patients with DDH start to have symptoms at a very early age, and the development process of the disease is relatively long, many of them may have decades of “disease age”, and they are already familiar with “cripples”, so they are skeptical about the effect of surgery. The bony structure of the hip of adult DDH patients is different from that of normal people, and the lack of bone volume also makes the surgery difficult. However, the perfect design of the artificial hip prosthesis and the maturity of hip replacement surgery technology nowadays can accomplish such a challenge well, allowing patients to achieve the surgical objectives of relieving hip pain, restoring the function of the hip joint, restoring the length of the lower limb, and reducing claudication.