In FAI, bone spurs develop around the femoral head and/or along the acetabulum. The bone overgrowth causes the hip bones to hit against each other, rather than to move smoothly. Over time, this can result in the tearing of the labrum and breakdown of articular cartilage (osteoarthritis).


There are three types of FAI: pincer, cam, and combined impingement.

Pincer. This type of impingement occurs because extra bone extends out over the normal rim of the acetabulum. The labrum can be crushed under the prominent rim of the acetabulum.

Cam. In cam impingement the femoral head is not round and cannot rotate smoothly inside the acetabulum. A bump forms on the edge of the femoral head that grinds the cartilage inside the acetabulum.

Combined. Combined impingement just means that both the pincer and cam types are present.


FAI occurs because the hip bones do not form normally during the childhood growing years. It is the deformity of a cam bone spur, pincer bone spur, or both, that leads to joint damage and pain. When the hip bones are shaped abnormally, there is little that can be done to prevent FAI.

Because athletically active people may work the hip joint more vigorously, they may begin to experience pain earlier than those who are less active. However, exercise does not cause FAI.


People with FAI usually have pain in the groin area, although the pain sometimes may be more toward the outside of the hip. Sharp stabbing pain may occur with turning, twisting, and squatting, but sometimes, it is just a dull ache.


Procedural options for FAI include a diagnostic hip joint injection to insure your pain is coming from within the hip joint which should be the case if your pain is secondary to FAI.  Cortisone injections can help with pain from this condition but are not a good long term solution. Regenerative type injections such as platelet-rich plasma (PRP) have been used to manage the recovery of labral injuries, a secondary effect of FAI, but with a bone/structural abnormality, surgery may be necessary.