In a normal hip, the head of the femur (thigh bone) fits well into the socket (acetabulum) whereas in hip dysplasia, the socket and femoral head are not congruent because of their abnormal development. The socket is characteristically shallow leading to under-coverage of the head. Over time, the head may leave the socket (dislocate). During the adult life, patients with hip dysplasia, have a higher chances of developing arthritis and require hip replacement surgery. Depending on the severity of the case, hip replacement surgery can be straightforward or more complex.