Hip dysplasia means that the hip socket is shallow or that the hip joint is the wrong shape and fails to completely support the femoral head. A joint that is the wrong shape or shallow will wear out faster than one that has a more normal shape. The smooth surface of the joint has a thin layer of cartilage that can’t be repaired or re-grown by the body. This cartilage surface needs to last a lifetime, or stiffness and pain can occur as the joint wears out.