Arthroscopic Surgery for Femoral-Acetabular Impingement (FAI)
This minimally-invasive surgical procedure is used to identify and correct problems in the hip joint, such as a torn labrum or damaged articular cartilage, that commonly result from femoral-acetabular impingement.
Femoroacetabular impingement, also known as FAI or hip impingement, involves an abnormality in the way the ball of the femur and the acetabulum (hip socket) fit together. An improper shape of the ball and socket creates excess friction in the joint and may cause a significant amount of discomfort. The condition is typically characterized by sharp pains in the groin area, although the pain may be located nearer to the outside of the hip.
In its early stages, FAI can often be relieved by conservative measures, including over-the-counter anti-inflammatory medications and rest. However, if symptoms continue, more extensive treatment may be recommended. Eventually, arthroscopic surgery to correct FAI may become necessary, particularly if hip damage has occurred.
Types of Femoroacetabular Impingement
There are several types of FAI, all of which are caused by abnormalities in the hips. These include:
- Pincer Impingement. Pincer impingement occurs when there is an abnormality in the way the ball of the femur (thighbone) and the acetabulum (hip socket) fit together. An improper shape of both the ball and the socket creates excess friction in the joint and may cause the hip to "jam" in front when bending forward.
- Cam Impingement. In patients with cam impingement, the highest part of the thigh bone (the femoral head), which is normally rounded, is not round and cannot rotate smoothly inside of the acetabulum. This leads to a grinding of cartilage within the acetabulum.
- Combined Impingement. Combined impingement results when both pincer and cam impingement are present in the hip.
Causes of Femoroacetabular Impingement
FAI is a common condition that is found in men more often than women. It usually occurs due to abnormal formation during childhood growth, because of a bone spur that develops on a hip bone. Therefore, there is no way to prevent FAI from developing. Since athletes face a higher risk of placing excessive pressure on their hips, they may be more likely to experience FAI pain at an earlier point than those who do not regularly participate in sports. However, there is no evidence that exercise leads to FAI.
Symptoms of Femoroacetabular Impingement
Femoroacetabular impingement is typically characterized by sharp pains in the groin area or toward the outside of the hip. Additionally, many patients experience intense, stabbing pain when performing certain motions, including squats, twists and turns. Dull aches are also a common symptom of the condition. Conversely, there are some patients with FAI who are completely asymptomatic. When symptoms do occur, it is typically an indication of damage to the cartilage.
Diagnosis of Femoroacetabular Impingement
A diagnosis of FAI is made after an examination and evaluation of symptoms. Typically, a series of tests will be performed as well, including an exam known as an impingement test. This test involves bringing the patient's knee up toward the chest and rotating it inward, closer to the opposite shoulder. If the impingement test produces hip pain, it is diagnosed as FAI. Imaging tests, such as X-rays and MRI or CT scans, are often conducted to confirm the presence of FAI.
Arthroscopic Surgery for Femoroacetabular Impingement
Over time, hip impingement can produce tears or wear down the hip cartilage, causing pain, swelling, stiffness and loss of mobility. If any damage to the hip is present and the symptoms are affecting a patient's daily activities, arthroscopic surgery for FAI may be necessary.
During arthroscopic surgery, a flexible tube with a camera on one end, known as an arthroscope, is inserted through a small incision to provide the surgeon with a clear view of the inside of the hip. Specialized surgical tools are inserted through one or more additional tiny incisions, allowing the doctor to make repairs or remove damaged cartilage. Depending on the type of the impingement the patient has, the bump on the femoral head may be shaved and the rim of the acetabulum may be trimmed.
Results of Arthroscopic Surgery for Femoroacetabular Impingement
Arthroscopic surgery can significantly reduce symptoms of impingement, and the procedure may help prevent future damage to the hip joint. It is a successful technique for improving the function of the joint and promoting a fuller range of movement. However, the surgery may not be able to completely resolve all the FAI-related problems, especially if the damage to the hip was extensive. Even after undergoing surgery, some patients may need additional treatment in the future.