Femoroacetabular impingement (FAI) is a condition where the bones of the hip are abnormally shaped.
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.
Because they do not fit together perfectly, the hip bones rub against each other and cause damage to the joint.Evidence is emerging that subtle abnormalities around the hip, resulting in femoroacetabular impingement (FAI), may be a contributing factor in some instances to osteoarthritis in the young patient.
FAI is the abnormal contact or friction between the femoral neck/head (ball) and the acetabular margin (socket), causing tearing of the labrum and avulsion of the underlying cartilage region, continued deterioration, and eventual onset of arthritis.
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.
Because athletically active 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.
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, but sometimes, it is just a dull ache.
During your first appointment, your Wisconsin Bone & Joint doctor will discuss your general health and your hip symptoms. He or she will also examine your hip.
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.
Your doctor may order imaging tests to help determine whether you have FAI.
X-rays. These provide good images of bone, and will show whether your hip has abnormally shaped bones of FAI. X-rays can also show signs of arthritis.
Computed tomography (CT) scans. More detailed than a plain x-ray, CT scans help your doctor see the exact abnormal shape of your hip.
Magnetic resonance imaging (MRI) scans. These studies can create better images of soft tissue. They will help your doctor find damage to the labrum and articular cartilage. Injecting dye into the joint during the MRI may make the damage show up more clearly. Your doctor may also inject a numbing medicine into the joint as a diagnostic test. If the numbing medicine provides temporary pain relief, it confirms that FAI is the problem.
Activity changes. Your doctor may first recommend simply changing your daily routine and avoiding activities that cause symptoms.
Non-steroidal 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.
If tests show joint damage caused by FAI and your pain is not relieved by nonsurgical treatment, your doctor may recommend surgery.
Many FAI problems can be treated with arthroscopic surgery.
Arthroscopic procedures are done with small incisions and thin instruments. The surgeon uses a small camera, called an arthroscope, to view inside the hip.
During arthroscopy, your doctor can repair or clean out any damage to the labrum and articular cartilage. He or she can 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.
Surgical management involves dislocation of the hip (while preserving the blood supply to the femoral head) and femoroacetabular osteoplasty.
Encouraging results have been reported following femoroacetabular osteoplasty and arthroscopic treatment of femoroacetabular impingement.