What is Femoral Acetabular Impingement?

Femoral Acetabular Impingement (FAI) is a condition in which extra bone grows along one or both of the bones that form the hip joint, giving the bones an irregular shape. Over time, the bones may rub against each other because they do not exactly fit, which can damage the joint, causing pain and limiting activity. The extra bone growth commonly occurs around the femoral head or along the acetabulum (hip socket). This can result in tears of the labrum and breakdown of articular cartilage or osteoarthritis.


Types of FAI

  1. Pincer: The extra bone extends out over the normal rim of the acetabulum. The labrum can be crushed under the prominent rim of the acetabulum.
  2. Cam: 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.
  3. Combined: Both the pincer and cam bone growth are present.


FAI occurs because the hip bones do not form normally during the childhood growing years. When the bones are shaped abnormally, there is little that can be done to prevent FAI. Some people who have FAI may live long active lives and never have problems while others may develop symptoms and this usually indicates that the disease is likely to progress.



The most common symptoms of FAI are pain, stiffness and limping. Pain often occurs in the groin area, although it may occur toward the outside of the hip. Turning, twisting, and squatting may cause a sharp, stabbing pain.



Activity changes: Your doctor may ask you to change your daily routine to avoid the activity that caused FAI.

Anti-inflammatory medications: Drugs such as ibuprofen can be provided in a prescription-strength form to help reduce the pain and inflammation.


Physical Therapy: Specific exercises can improve the range of motion in your hips and strengthen the muscles that support the joint. This can relieve some stress on the injured labrum or cartilage.