Femoroacetabular impingement (FAI) is a pinching of the soft tissues close to, next to, or around the hip. Femoroacetabular tells us the impingement is occurring where the femur (thigh bone) meets the acetabulum (hip socket). There are several different types of impingement. They differ slightly depending on what gets pinched and where the impingement occurs.
One of the main areas affected is the labrum, the rim of fibrous cartilage around the hip socket that your surgeon may repair or trim away. The labrum is designed to give the hip a bit more depth and stability. But even a small amount of asymmetry of the hip socket and/or femoral head in the hip socket can cause impingement of the labrum with certain hip motions.
For example, a slightly oval shape instead of a perfectly round head of the femur or a slightly off-angle of the socket can result in painful pinching of the labrum or other soft tissues of the hip.
Sometimes it’s a case of a hip socket that’s deeper than normal. Over time, this pinching or impingement of the labrum can cause fraying and tearing of the edges and/or osteoarthritic changes at the impingement site.
The affected individual experiences hip and/or groin pain along with decreased hip motion. The condition may look like a chronic muscle strain or groin injury but an X-ray, CT scan, or arthroscopic examination confirms femoroacetabular impingement as the true cause of the problem.
Surgery may be needed to restore normal hip motion. Whenever possible, surgery is done arthroscopically to repair the damage. The surgeon trims the acetabular rim and then reattaches the torn labrum. This procedure is called labral refixation.
Each layer of tissue is sewn back together and reattached as closely as possible to its original position along the acetabular rim. When repair is not possible, then debridement (shaving or removing) the torn tissue or pieces of tissue may be necessary.
Postoperative care and recovery may depend on your age, your surgeon’s preferences, and the exact type of surgery that is done. Most patients go home the same days as the surgery.
A standard rehab program often includes six weeks in a splint to keep the hip quiet. For the first few weeks, you’ll probably be allowed to put a small amount of weight on the foot — so long as you use crutches and don’t put your full weight down.
A physical therapist will teach you and a family member how to move the leg/hip passively (without using active muscle contraction). Gradually, you will be allowed to begin active movement.
The therapist will guide you through a series of phases from passive motion to active motion and finally to strengthening and conditioning. You can expect to be in some type of rehab program for about three months. Most of this is done at home on your own with occasional visits to the physical therapy clinic to make sure you are doing the exercises correctly and to progress the program along as you improve.