Understanding Your Diagnosis

The hip joint is a ball and socket joint that is formed from the femur, or thigh bone, and the acetabulum, or the hip socket. In an ideal hip, these parts fit together perfectly like a puzzle. Both the ball and socket are lined in a smooth cartilage that cushions the joint, called articular cartilage. On the rim of the socket, there is a specialized fibrocartilage called the labrum. The labrum helps to suction seal the joint and acts as a gasket to keep the joint fluid in the joint.

In this episode of eOrthopodTV, orthopaedic surgeon, Randale C. Sechrest, MD, narrates an animated tutorial on the anatomy of the hip joint.

Hip Impingement / FAI

In many hips, the head of the femur (ball) and the acetabulum (socket) don't fit together perfectly, causing abnormal contact and friction in the joint. This underlying structural problem of the hip is called hip impingement, or femoroacetabular impingement (FAI). After repetitive contact from repetitive activities, like running or kicking, FAI causes the joint to get inflamed and become painful. If left untreated, it can also cause cartilage damage and progress the development of arthritis in the hip joint.

There are three forms of FAI: CAM impingement, Pincer impingement and Mixed impingement (involving both CAM and pincer type). In CAM impingement, the femur (ball) has boney growth on it that contacts the hip socket during movement. In pincer impingement, the acetabulum, or socket, covers the ball too much causing abnormal contact. The accompanying videos show the anatomy of each type of impingement.