Select Page

Femoroacetabular Impingement (FAI): A Closer Look

The socket portion of the hip joint, called the acetabulum, is part of the pelvis. The femoral head (the upper end of the thighbone called the femur) is a ball that fits into the socket.


Tissue called articular cartilage covers the surface of the ball and the socket. It creates a smooth, frictionless surface that helps the bones glide easily across each other. The acetabulum is ringed by strong fibrocartilage called the labrum. The labrum forms a seal around the socket.


Femoroacetabular impingement (FAI) is a condition that occurs when the bony socket (acetabulum) and the femoral head repetitively come into contact with each other. Over time, this can result in the tearing of the labrum and breakdown of articular cartilage and ultimately result in arthritis.

Types of FAI

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

  • Pincer- when extra bone extends out over the normal rim of the acetabulum. The labrum can be crushed under the prominent rim of the acetabulum and result in a tear
  • Cam- when 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- A combination of the above two conditions


People with FAI usually have pain in the groin area, although pain can also occur laterally or posteriorly. Symptoms can include a dull ache or a stabbing pain with twisting and squatting. Athletic exercise will not cause FAI but may aggravate your symptoms.


Your surgeon will discuss options for treatment for this problem but could include