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Femoroacetabular Impingement (FAI) refers to a condition in which the two bones of the ball and socket joint of the hip do not articulate smoothly and hip joint damage and associated symptoms are present. FAI is caused by an alteration in the shape of the head of the femur (the ball) and/or imperfections in the part of the pelvic bone known as the acetabulum (the socket).

The hip joint is located at the meeting point of the rounded head of the femur and the cavity-shaped acetabulum of the pelvic bone. This ball and socket joint bears the weight of the body as well as the tremendous forces generated with activities such as walking, running and jumping. As one of the most flexible joints in the body, the hip allows a greater range of motion than all other joints with the exception of the shoulder.

Femoroacetabular impingement is the result of bony deformities of the ball and/or the socket, which prevent smooth movement of the hip and can produce joint damage. It is often associated with damage to the cartilage, labral tears, and progressive osteoarthritis of the hip. While FAI may lead to pain and eventual loss of motion of the hip for many individuals, there are others who have FAI and never have problems.

Although exercise does not cause FAI, and anyone can develop the condition, it is frequently seen in athletes and active individuals. Symptoms of FAI can include pain, stiffness and limping. Individuals with FAI may first notice an intermittent pain in the front of the hip or groin area. In some cases pain can be present along the side of the thigh and buttocks. The discomfort may be experienced as a sharp stabbing sensation or a dull ache.

Diagnosis of FAI begins with a history and physical examination. In checking for the presence of FAI, the doctor will likely perform an impingement test during which the knee is brought up to the chest and rotated towards the opposite shoulder. Imaging tests will be ordered to further evaluate the hip, locate the bony deformities, as well as assess the joint damage.

If FAI is present initial treatment may involve a conservative non-surgical approach that includes avoiding activities that cause discomfort, non-steroidal anti- inflammatory medications, and physical therapy. However, if it is determined that joint damage is present and symptoms are not relieved by a conservative course of therapy, surgery will be recommended.