What is developmental dysplasia of the hip (DDH)? The hip joint is the joint that connects the pelvis to the thigh bone and is a “ball and socket joint”. In a normal hip joint, the femoral head is smooth and spherical, while the acetabulum is smooth and cup-shaped, with the femoral head and acetabulum in close contact, somewhat similar to an egg in an egg cup. In DDH, not only is the shape of the femoral head and acetabulum, which make up the hip joint, abnormal, but the supporting structures around them are also faulty. The result is a loss of close contact between the acetabulum and the femoral head. This developmental abnormality can be mild, meaning that there is still some contact between them, which we call “subluxation”. It can also be severe, where there is no contact between the acetabulum and the head of the femur, which is called a “total dislocation”. Why do developmental hip abnormalities occur? The reasons for this are not well understood, but a number of factors are known to increase the chance of developing the condition. Family history: If a parent or sibling has DDH, there is a 5-fold increase in the likelihood of developing the disease. Breech delivery or breech position in the second trimester of pregnancy. Gender: 4 out of 5 children with DDH are girls (especially girls in the first trimester). Comorbidity with other congenital disorders such as horseshoe foot deformity, oblique neck, etc. What are the signs and symptoms of DDH? Newborns with DDH do not cry or feel pain all the time. Usually, the child’s health care provider will perform a regular physical examination of the child, one of which is to screen for the presence of DDH. The doctor will hold the child’s knees apart on each side to the sides, like opening a book. The doctor does this to feel if there is a popping sensation or limited abduction of the hip joints on both sides during abduction. Once this is detected, it is a sign that there may be a problem with that side of the hip. Hip problems may also manifest themselves in the following two ways: Asymmetry between the hip and thigh lines. One side of the thigh looks shorter than the other.