Hip Dysplasia and Hip Impingement
Your hip is a ball-and-socket joint. The ball at the top of your thigh bone, or femur, fits into a socket in your pelvis called the acetabulum. Hip dysplasia is when the socket doesn’t adequately cover the ball. This may be because the socket is too small or shallow, isn’t positioned correctly, or both.
Hip impingement (also called femoroacetabular impingement, or FAI) is when normal movement results in abnormal contact between the ball and socket of your hip joint. Typically, this happens when the socket, ball, or both have an irregular shape. The result is wear of your hip joint.
In both hip dysplasia and hip impingement, some of the earliest symptoms are caused by irritation or tearing of the hip labrum, a type of cartilage that lines the rim of the hip socket. A hip labrum tear is nearly always the result of an underlying condition, so treating the labral tear alone makes it likely your hip pain will eventually return. Over time, untreated hip dysplasia or hip impingement can lead to arthritis and, eventually, hip replacement surgery.
Avascular necrosis (AVN) of the femoral head is when part of the ball at the top of your thigh bone loses blood supply, causing that segment of bone to die. Your body tries to heal the area by replacing the dead bone with new, live bone. Unfortunately, the new bone is weaker than normal bone, causing pain when you put weight on it. Eventually, the weak area collapses and the ball no longer fits well in the socket. Over time, this irregular bone wears away the cartilage in your hip joint, causing arthritis.