Femoroacetabular Impingement (FAI)

Femoroacetabular Impingement

Femoroacetabular 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. Because they do not fit together perfectly, the bones rub against each other during movement. Over time this friction can damage the joint, causing pain and limiting activity.

HIP ANATOMY

The hip is a ball-and-socket joint. The socket is formed by the acetabulum, which is part of the large pelvis bone. The ball is the femoral head, which is the upper end of the femur (thighbone).

Articular cartilage, which is a smooth slippery surface that covers the surface of the ball and the socket. This surface helps the bones slide across each other easily during movement.

The acetabulum (socket) has a strong fibrocartilage called the labrum. The labrum forms a gasket around the socket, creating a tight seal and helping to provide stability to the joint.

In a healthy hip, the femoral head (ball) fits perfectly into the socket.

In FAI, bone overgrowth, referred to as bone spurs, develop around the ball and/or along the socket. This extra bone causes abnormal contact between the hip bones, and prevents them from moving smoothly during activity. Over time, this can result in tears of the labrum and the breakdown of articular cartilage (osteoarthritis).

Types of FAI

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

• Pincer: This type of impingement occurs because the bone spur extends out and over the normal rim of the socket allowing the labrum to be pinched.
• Cam: In cam impingement the ball is not round and therefore cannot rotate as smoothly inside the joint socket. A bump forms on the edge of the ball that grinds the cartilage inside the socket.
• Combined: Combined impingement means that both the pincer and cam types are present.

CAUSE

FAI occurs because the hip bones do not form normally during the childhood growing years. It is the deformity of a cam bone spur, pincer bone spur, or both, that leads to joint damage and pain. When the hip bones are shaped abnormally, there is little that can be done to prevent FAI.

It is not known how many people have FAI. Some people may live long, active lives with FAI and never have problems. When symptoms develop, however, it usually indicates that there is damage to the cartilage or labrum and the disease is likely to progress.

Because athletic people may work the hip joint more vigorously, they may begin to experience pain earlier than those who are less active. However, exercise does not cause FAI.

SYMPTOMS

The most common symptoms of FAI include:

• Pain often a dull ache, occurs in the groin area or towards the outside of the hip
• Turning, twisting, and squatting may cause a sharp, stabbing pain.
• Stiffness
• Limping

When symptoms first occur, it may be difficult to determine if an activity or something you may have done could have caused the pain as many times the pain/ache is a gradual onset. Sometimes, you can modify your activities, let your hip rest, and see if the pain will settle down. Over-the-counter anti-inflammatory medicines, such as ibuprofen and naproxen, may help.

If your symptoms persist, you will need to see a doctor to determine the exact cause of your pain and provide treatment options. The longer painful symptoms go untreated, the more damage FAI can cause in the hip.

DIAGNOSING FAI

During your first appointment, your doctor will discuss your hip symptoms, thoroughly examine your hip and obtain x-rays. As part of the physical examination, your doctor will likely conduct the impingement test. For this test, your doctor will bring your knee up towards your chest and then rotate it inward towards your opposite shoulder. If this recreates your hip pain, the test result is positive for impingement.

An x-ray provides a high-quality image of the bone and can confirm FAI is present and in most cases, determine the extent of the bone overgrowth. X-rays are also used to determine if there are any signs of arthritis present.

After examination and x-rays, your doctor may order magnetic resonance imaging (MRI) scans to further assess your condition. MRI studies provide an image of the soft tissues. These images identify damage to the labrum and articular cartilage. An arthrogram (the injecting of dye into the joint) is done prior to the MRI to allow the damage to show up more clearly.

Nonsurgical Treatment

• Activity modifications.
• Nonsteroidal anti-inflammatory medications. Drugs like ibuprofen can be provided in a prescription-strength form to help reduce pain and inflammation.
• Physical therapy. Specific exercises can improve the range of motion in your hip and strengthen the muscles that support the joint. This can relieve some stress on the injured labrum or cartilage.
• Injection of steroids to reduce inflammation and pain.

Surgical Treatment

If tests show joint damage caused by FAI and your pain is not relieved by nonsurgical treatment, your doctor may recommend arthroscopic surgery to remove the bone spurs and/or repair the damage caused by FAI.

Long-Term Outcomes

Surgery can successfully reduce symptoms caused by impingement. Correcting the impingement can prevent future damage to the hip joint. However, not all of the damage can be completely fixed by surgery, especially if treatment has been put off and the damage is severe. It is possible that more problems may develop in the future.  While there is a small chance that surgery might not help, it is currently the best way to treat painful FAI.

If you are experiencing dull aching pain, don’t chance it. Get a swift, accurate diagnosis and advanced treatment by calling the specialists at Orthopedic Specialists today.