This is the medical term for the hip socket that does not fully cover the ball portion of the upper thigh bone. This allows the hip to become partially or completely dislocated. Most people with hip dysplasia are born with this condition. https://www.evidence.nhs.uk/search?ps=50&q=hip+dysplasia
Milder cases of hip dysplasia might not start causing symptoms until a person is a teenager or young adult.
Hip dysplasia tends to run in families and is more common in girls. The risk of hip dysplasia is also higher in babies born in the breech position and in babies who are swaddled tightly with the hips and knees straight.
Later in life hip dysplasia can damage the soft cartilage (labrum) that rims the socket portion of the hip joint. This is called the labral tear. Hip dysplasia can also make the joint more likely to develop osteoarthritis. This occurs because of higher contact pressures over a smaller surface of the socket.
Hip dysplasia treatment depends on the age of the affected person and the extent of the hip damage. Infants are usually treated with a soft brace that holds the ball portion of the joint firmly in its socket for several months. This helps the socket mould to the shape of the ball.
If the brace does not work well, especially in babies older than 6 months, the orthopaedic doctor may move the bones into the proper position and then hold them there for several months with a full-body cast. Sometimes surgery is needed to fit the joint together properly.
If dysplasia is more severe, the position of the hip socket can also be corrected. In operation called periacetabular osteotomy, the socket is cut free from the pelvis and then repositioned so that it matches up better with the ball.
Acetabular osteotomy is commonly used as a surgical treatment for hip dysplasia in adolescents.
Hip replacement surgery might be an option for older people whose dysplasia has severely damaged their hips over time, resulting in debilitating arthritis. Patients with developmental dysplasia of the hip have a high incidence of sciatic nerve injury after total hip arthroplasty. A high incidence of sciatic nerve injury may be related to the over-lengthening of the lower-limb in total hip arthroplasty and the complexity and difficulty in performing the surgery. https://www.nhs.uk/conditions/developmental-dysplasia-of-the-hip/