Femoroacetabular Impingement (Hip Impingement)

Femoroacetabular Impingement (FAI) is a relatively new diagnosis for hip pain. It was originally described in Europe in the mid-1990’s and has subsequently been a heavily studied topic with an explosion of research published in the last decade. FAI describes a pattern of abnormal anatomy of the hip joint that with certain activities, and in certain patients, can lead to damage to both the cartilage that lines the hip joint and to the labrum (a cartilage rim around the acetabulum or hip socket). Both of these can cause pain and limitation in activity. It can also present as a limitation in motion as these abnormalities in the bone size or shape limits the ability to achieve certain hip positions fully and without pain. This can cause problems for any patient, however those that tend to be most commonly affected are runners, cyclists, golfers, tennis players, soccer players and gymnasts because of the positions their hips must be in for many aspects of competition.

The abnormality in the bone structure can be on the femur (ball) or the acetabulum (socket) but most commonly is present on both sides. Classic patterns of cartilage and labral damage will occur based on which type of bone abnormality is dominating. Most commonly it is due to excess bone in very specific locations, rather than not enough bone…however this can be a problem as well. These areas of “extra” bone act as road blocks during hip motion and as the hip moves, these areas impact one another and lead to “impingement”. This impingement is what can block motion, can cause damage to the labrum (cartilage rim around the socket), and damage the articular cartilage (cartilage lining the joint). The most common areas of involvement are the anterolateral (front and side) aspect of the femoral head-neck junction (where the ball joins the rest of the thigh bone), and the anterosuperior (front and top) aspect of the acetabulum (socket). These areas come into contact mostly with the hip in deep flexion, which can occur in many sports (cycling, football, soccer, gynmastics, tennis and others) and daily activities (putting on shoes and socks, crossing legs, gardening, walking hills or stairs, and driving for example)

Typically FAI presents as pain in the hip and groin areas. It can be a dull, achy, annoying pain, or it can be very focal, sharp pain. Most people feel that the pain is much worse with certain specific activities and they can often reproduce the symptoms when asked.

The pain itself can come from many sources including stress on the bone, damage to the cartilage, tears in the labrum, and inflammation in the joint. Often the muscles around the hip and pelvis become weakened in conjunction with this and may be a significant factor as to why symptoms develop without a known injury. This may also be the reason that they do not improve over time.

FAI is diagnosed by several means. Specialized physical exam tests are performed during your clinic visit to evaluate muscle balance, range of motion and potential areas of pain. Additionally, special xrays are taken to evaluate the shape, size, and position of the hip joints on both sides. These are used for specialized measurements and can also demonstrate evidence of arthritic changes (as a result of chronic cartilage damage and loss). A unique MRI is also performed to further evaluate the hip joint by investigating the labrum (which can not be seen on xrays) and the joint cartilage, as well as surrounding areas of muscles, tendons and ligaments. This should be performed in a very specific method to focus closely on the hip joint itself and will involve an injection of local anesthetic (numbing medicine) and contrast dye (a safe fluid that enhances the MRI image and diagnostic power). This will improve the utility of the MRI itself and will also help confirm that the pain is coming from inside the hip joint, which is helpful if surgery is being considered.

FAI is both an anatomic and dynamic or functional problem. Most people with FAI have had the abnormal anatomy for their entire life and at some point it becomes symptomatic. This may be with participating in certain activities that ultimately bring the bones into these trouble positions, or if a discrete injury occurs, or simply over time as the tissue finally breaks down. If weakness in the core musculature, hip and pelvis muscles, and abdominal muscles is a large component, then physical therapy my be helpful to re-establish balance to these areas and protect the hip. However, once sufficient damage is done in the joint, or if the anatomic abnormality is too great, then therapy will not be enough and surgery should be considered.

Research has demonstrated clearly that if all aspects of the problem (bone abnormality, cartilage damage, labral tear, etc.) are treated at the same time, then the results are quite good. However, if only a portion of the problem is identified and treated, then patients do not do very well and success rates of the surgery drop off to approximately 65-75%. This is the reason for combining multiple means of evaluation including the physical exams, x-rays and MRI to completely characterize the problem before a treatment is recommended.

Some surgeons, including the group that first described this problem, treat this with a relatively large surgery that requires a sizable incision and a surgical dislocation of the hip joint. A certain subset of sports medicine surgeons around the world have adapted a means to complete the same procedure with excellent outcomes through an arthroscopic (“microscopic”) procedure. The benefits of this type of surgery are significant, including fewer risks, less pain, quicker recovery, and only a few tiny incisions around the hip joint. This arthroscopic procedure may involve repair or partial removal of the labrum, removing loose fragments of cartilage, special techniques to stimulate new cartilage growth, reshaping the bones, tendon releases, removal of scar tissue and inflammation, improving stability of the hip joint and other related procedures.

Common Questions:

What should I do if I suspect I have FAI or a Labral Tear in my Hip?

You may contact my clinic any time to arrange for an appointment to discuss your specific symptoms. We can be reached at (408) 866-6651. I will discuss your condition with you in detail and we can arrange for any needed xrays or MRI as well.

What should I avoid doing if I have FAI or a Labral Tear in my Hip?

Answered simply, avoid the positions that cause pain. The positions that typically make symptoms worse and cause continued damage to the labrum and cartilage are deep hip flexion (squatting and bending positions). Also, hip rotation often worsens the symptoms (crossing legs, twisting positions). Impact loading the hip (running and jumping) will also make the symptoms worse.

If I have this condition, when should I seek treatment?

This is not an emergent condition and typically the severity of your symptoms can guide you as to when you should seek treatment. The damage within the hip joint is somewhat progressive but typically not rapidly. Traditionally, making the correct diagnosis has been the limiting step as not many general physicians understand this condition or how to diagnosis it. Many patients go several months or even years before they are appropriately diagnosed. Usually the sooner this condition is treated, the better…however, it should be done when it is convenient as there is a moderate amount of rehabilitation after surgery that will need to be completed as well. The key is to have the diagnosis made and understand the extent of your particular problem.

If I do have arthroscopic surgery to correct the problem, how long before I am fully recovered?

There is significant variability in the post-operative rehabilitation required after this type of surgery based on which of the procedures will be required. However, typically physical therapy will be instituted immediately after surgery and continue for a few months. Typically, “full recovery” (clearance to do any activity without restriction) is not before 3 months, yet this is dependent upon the specifics of the surgical procedures you would need.

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