The hip joint is shaped like a ball and socket. The “ball” is the femoral head (the top of the thigh bone/femur) and the “socket” is the pelvis (or acetabulum), which is shaped like a cup. In hip dysplasia, the socket is too shallow, meaning the femoral head is not held in place correctly. This can cause the joint to function incorrectly, leading to injuries and, in more severe cases, the ball coming out of the socket (known as dislocation). The condition puts extra pressure on the hip, so it will usually “wear out” more quickly. This can cause arthritis or the need for joint replacement. It ranges from very mild to severe and can affect one or both sides of the hip. Hip dysplasia usually occurs in newborns or young babies, but symptoms and diagnosis may not happen until adolescence or adulthood.