Femoroacetabular Impingement (FAI)

ValleyOrtho’s experienced and compassionate team of physicians treat a vast array of hip conditions, including Femoroacetabular Impingement (FAI) also known as hip impingement.


The hip joint is made from the connection of the top, ball shaped, end of the thighbone (femur) and the socket of the pelvis (acetabulum), which allows for motion in nearly all directions. In hip impingement, or FAI, the structure of the hip is subtly altered, resulting in abnormal motion. The ball and socket of the hip do not quite fit together properly, resulting in abnormal mechanics and eventual damage to the joint. Long-standing, untreated FAI may actually be one of the most common causes of osteoarthritis of the hip.

There are two types of hip impingement:

  • Cam impingement occurs when the ball of the hip joint is not perfectly round.
  • Pincer impingement occurs when the socket of the hip overhangs and impinges (presses) against the ball.

In both cases this can lead to labral tears, cartilage damage and hip pain.


People with FAI may have been born with a structurally abnormal ball-and-socket joint. In other cases, the hip joint may have become structurally abnormal during development. Repetitive activity involving recurrent movement of the legs beyond the normal range of motion may cause hip impingement. This has often been observed in certain athletes (football, baseball, soccer, tennis, hockey, lacrosse players, dancers, and golfers).


People with FAI or hip impingement generally have deep pain in the groin and limited hip rotation. Pain is usually activity related but may also occur when the hip is bent, such as with prolonged sitting. Because the bone changes that occur in FAI often lead to labral tears, the symptoms of FAI and labral tears are very similar.


FAI is usually diagnosed by a detailed medical history and physical examination. Specialized x-rays are also necessary to evaluate the bone structure of the hip. A specialized MRI is used to diagnose labral tears, which often occur in people with FAI.


Treatment of FAI is individualized, based on symptoms and imaging (x-ray and MRI). Some people with mild symptoms and minor bone changes respond well to physical therapy and activity modification.

However, when FAI is severe or in highly active individuals, surgical treatment may be required. In most cases of FAI, the bone of the hip can be recontoured arthroscopically, recreating a normal joint surface and thereby improving symptoms and flexibility.