Femoro-acetabular impingement (FAI)

What is femoro-acetabular impingement?

Femoro-acetabular impingement (FAI) is also known as hip impingement.

The hip is a ball-and-socket joint. The ball at the top of the leg bone is called the femoral head. It fits into the socket, called the acetabulum, which is in the pelvis bone.

FAI occurs when either the ball or the socket has an abnormal shape that makes the two bones rub against each other. This causes damage to the hip joint.

FAI symptoms

FAI may cause a general ache around the hip, or it could cause more specific types of pain, such as:

  • in the groin
  • on the outside of the hip
  • during movements such as twisting or squatting

FAI causes and risk factors

FAI is caused by bones that did not grow normally during childhood.

FAI treatment options

If the pain from FAI is not severe, your doctor may recommend resting the hip and taking anti-inflammatory medicine such as ibuprofen.

If your FAI pain does not go away or if it becomes worse, your doctor may want to take scans or X-rays to find out what part of your hip is causing the pain.

FAI is sometimes treated with arthroscopic surgery, which involves the doctor inserting instruments into small incisions near your hip and trimming parts of the bones that are rubbing together.

Last reviewed: 
July 2018
Alternative Names: 
Hip impingement

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