DDH refers to abnormal development or growth of the hip resulting in hips that are dislocated or sublux due to reduced congruence between the femoral head (thigh bone) and acetabulum (hip socket). Normal development of the hip relies on pressure from a normal femoral head to stimulate normal growth and increased depth of the acetabulum. 


Can be the result of other congenital disorders during development of the hip or due to mechanical forces. There is a higher risk with breech babies, females, first borns, positioning following birth, and with other positional abnormalities such as torticollis and metatarsus adductus.


Treatment is most effective before the child reaches 9 months of age as they begin to stand and are close to walking age and is least likely to affect development. This involves application of a simple harness to pull the hip into optimal position. After this casting into abduction may be indicated.