Hip dysplasia (sometimes referred to as developmental dysplasia of the hip, or DDH) is a developmental problem with the hip joint. Severe cases are often picked up at birth or in childhood, but milder or missed cases may not present until adulthood. In this latter situation,it may only be discovered on an Xray when it becomes symptomatic.
The Xray image on the left shows a dysplastic hip. The acetabulum (or socket) of the hip joint is not sufficiently covering the femoral head (or ball). As a result, the loading forces within the hip joint are abnormal. In the early stages, this leads to damage to the labrum and rim of the hip joint. Left unchecked, it will often progress to arthritis.
In certain cases, where the degenerative process has not yet started, it is possible to preserve the hip joint by performing a reorientation procedure known as periacetabular osteotomy (PAO), sometimes in conjunction with a femoral osteotomy.