Femoroacetabular Impingement (FAI)

Femoroacetabular Impingement (FAI)

The Anatomy Of Femoroacetabular Impingement

Anatomically the hip joint is know as a ball and socket joint, the “socket” part of the joint is formed by the acetabulum, which is part of the large pelvis bone made up of the ilium, ischium and the pubis. Where as the “ball” part of the joint, is the femoral head, which is the upper end of the thighbone known as the femur. Both the ball and socket surfaces are covered in articular cartilage, a hard, slippery tissue helping create a strong smooth, low friction surface that helps the surfaces of the joint glide and slide easily against each other. The acetabulum of the hip is also ringed by a strong fibrocartilage wedge called the labrum, the labrum creates a tight seal around the joint, as well as helping to provide additional cushioning and stability to the joint. Femoroacetabular Impingement (FAI), or hip impingement syndrome is a situation where the spherical shaped femoral head and socket abut abnormally and normal range of motion is not permitted without the ball and socket impinging in some way. The bones of the hip joint impacting against each other with certain movements over time can result in damage to the labrum and articular cartilage of the hip joint and can be associated with discomfort and even functional limitations.

Three Types Of Femoroacetabular Impingement:

There are three types of FAI, one said to involve the socket, another the femoral head and the other a combination of both:

  • Pincer Impingement: The pincer version of hip impingement occurs because “extra” bone extends out over the rim of the hip socket. In a pincer FAI situation the labrum can be “crushed” under the prominent rim of the hip socket potentially causing pain.
  • Cam Impingement: With Cam impingement the femoral head is abnormally shaped and not its normal spherical self and does not rotate smoothly inside the socket. A cam deformity is characterised by extra bone formation causing a bump to form on the edge of the femoral head-neck junction, this bony formation can “grind” at the cartilage in the socket.
  • Combined: Combined impingement simply means there is a situation where both pincer and cam types of hip impingement are present.

FAI Is A Major Risk Factor For Osteoarthritis

In Femoroacetabular impingement bone overgrowth like these bone spurs developing around the hip joint the femoral head and/or along the acetabulum will basically stop the joint fitting together perfectly and these abnormally spurred surfaces can rub causing damage to the joint. Research has indicated that a high number of young adults who have undergone any hip arthroscope for femoroacetabular impingement, find that on examination the hip demonstrates signs of joint disease, reflecting early signs of hip osteoarthritis (OA). In fact a Cam deformity, one of the types of femoroacetabular impingement listed above has been identified as a major risk factor in end stage hip osteoarthritis.
Femoroacetabular impingement is often seen as a surgical problem and many people diagnosed with FAI visit an orthopaedic surgeon seeking relief and answers. Surgery is often a very effective solution, at least temporarily, for someone suffering with FAI. However physiotherapy too can play pivotal role in the management of femoroacetabular impingement, it is not uncommon to utilize more conservative approaches like targeted strengthening, stretching, activity modification, even shockwave therapy and other manual techniques to help manage pain and improve function prior to surgery and only should these measures fail to achieve desirable results would surgery be considered.

Disclaimer: Sydney Physio Clinic does not endorse any treatments, procedures, products mentioned. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific advice or assistance regarding Femoroacetabular Impingement should consult his or her podiatrist, sports medicine specialist or physiotherapist.