Femoroacetabular Impingement (FAI)
Other popular names
Who does it affect?
Generally more active people who work the hip joint more vigorously. However, exercise does not cause FAI.
Why does it happen?
Femoroacetabular impingement (FAI) is a condition where the bones of the hip are abnormally shaped. Because they do not fit together perfectly, the hip bones rub against each other and cause damage to the joint. It is quite often that this condition results from childhood in the growth years or in early adult life.
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). A slippery tissue called articular cartilage covers the surface of the ball and the socket. It creates a smooth, low friction surface that helps the bones glide easily across each other.
The acetabulum is ringed by 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 fits perfectly into the acetabulum.
In FAI, bone spurs develop around the femoral head and/or along the acetabulum. The bone overgrowth causes the hip bones to impact against each other, rather than to move smoothly. Over time, this can result in the tearing of the labrum and 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 extra bone extends out over the normal rim of the acetabulum. The labrum can be crushed under the prominent rim of the acetabulum.
- Cam. In cam impingement the femoral head is not round and cannot rotate smoothly inside the acetabulum. A bump forms on the edge of the femoral head that grinds the cartilage inside the acetabulum.
- Combined. Combined impingement just means that both the pincer and cam types are present.
People with FAI usually have pain in the groin area, although the pain sometimes may be more toward the outside of the hip. Sharp stabbing pain may occur with turning, twisting, and squatting, however sometimes, it is just a dull ache.
Your consultant will undertake a physical examination, moving and rotating your hip into various positions. One such movement is known as the impingement test, when your knee will be brought up towards your chest and then rotated inward towards your opposite shoulder. If this recreates your hip pain, the test result is positive for impingement.
It is likely that you will require an x-ray which will allow the consultant to see any abnormally shaped bones in your hip.
On occasion, an MRI arthrogram scan may be requested for more detailed review of the soft tissue.
When symptoms first occur, it is helpful to try and identify an activity or something you may have done that could have caused the pain. Sometimes, you can just back off on your activities, let your hip rest, and see if the pain will settle down. Over-the-counter anti-inflammatory medicines e.g. ibuprofen may help.
If your symptoms persist, you will need to see a consultant 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.
Many FAI problems can be treated with arthroscopic surgery. Arthroscopic procedures are done with small incisions and thin instruments with the surgeon using the arthroscope (camera) to navigate around the joint. During arthroscopy, I can repair or clean out any damage to the labrum and articular cartilage. I can also correct the FAI by trimming the bony rim of the acetabulum and also shaving down the bump on the femoral head. Some severe cases may require an open operation with a larger incision to accomplish this.
The aim is to mobilise patients as soon as possible after surgery - on the same day or the next day as this helps speed recovery.
Return to normal routine
Bathing and showering
The wounds should be kept clean and dry until the wound has sealed. Showering is fine and the waterproof dressings can be changed afterwards. Bathing is best avoided until the wounds are sealed, typically 4 to 5 days after surgery.
In summary, whilst the wounds are wet - keep them dry and when the wounds are dry, you can get them wet.
Patients should and try to minimize their activities as much as possible in the first few days following surgery. The leg should be rested and elevated as much as possible. Painkillers (supplied on discharge from hospital) and cold packs may be used as required.
Simple exercises, including straight leg raises and other exercises as instructed by your physiotherapist prior to discharge should be performed.
Most patients do not require formal physiotherapy following arthroscopy as all patients are seen and assessed by a physiotherapist prior to discharge from hospital.
Some patients might require physiotherapy either before or after the first post-operative check-up.
Return to activity
Recovery is a gradual process and whilst most patients bounce back quickly following arthroscopy everyone should assume it will take up to 6 weeks to make a full recovery and symptoms can often improve for some time beyond this period.
The speed of recovery depends on the surgery performed, the degree of degeneration found and the age of the patient.
In general, the older the patient and the more degeneration a patient has, the slower and less predictable recovery will be. Most patients can perform most tasks around the house and return to driving within a few days. Sedentary/office workers can often return to work a few days after surgery. Patients performing more physical work might require two to 6 weeks off work depending on their individual positions. Patients can usually return to sport between 3 to 6 weeks following surgery.
The small wounds can remain tender for a few months following surgery.
Return to driving
The leg needs to have full control of the pedals. You are advised to avoid driving for at least 7 days or you regain full use of your leg.
An Arthroscopy is an extremely safe routine operation with a very low complication rate. Overall over 97% are happy with the result. However complications can occur.
Potential complications include infection, injury to blood vessels and nerves and severe pain and swelling in addition to the rare general complications such as blood clots (DVT) and anaesthetic risks.
In general, the risk of sustaining a complication as a consequence of the operation that leaves you worse off in the long term is less than 1%.
The biggest practical risk is the risk of not being able to improve symptoms as much as desired or at all. This occurs most commonly due to the presence of degenerative changes.
Most ongoing symptoms following arthroscopic surgery are usually the result of the underlying problem within the hip.
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.