What Is Femoroacetabular Impingement (FAI)?

Femoroacetabular impingement (FAI), or hip impingement, is a condition where the ball of your thigh bone (femur) can’t move normally in your hip socket. This happens when there is too much bone around the ball (femoral head) or when the socket is angled slightly backward. This causes the femur to bump into or pinch the rim of the socket.

When the ball of your femur hits the rim of the hip socket, it can damage the cartilage and labrum in the joint. These are tissues that cushion the bones in your hip socket. Because of this damage, you may feel pain as the tissues start to get small tears and degenerate. These tears can lead to osteoarthritis over time.

Types of Hip Impingement

There are three types of hip impingement:

  1. Cam impingement means that there is a bump of extra bone growth on the ball or neck of the femur, so it is not round and can't fit into the socket normally. When you move the hip, the area that is not round forces itself into the socket and pinches the joint.
  2. Pincer impingement happens when the socket of the hip is too deep or covers too much of the femur. A deep socket will pinch sooner than a normal socket and can wear down the protective tissue (cartilage) lining of the joint.
  3. Combined impingement means that both cam and pincer impingement are happening in your hip joint. This is the most common type of hip impingement.

Find a Hip Specialist

What Causes FAI?

FAI is usually caused by an abnormality in the bones of your hip joint. This could be something that you were born with, or something that developed as you grew. Hip impingement could also be caused by an injury or by repetitive motions over a long period of time (especially in activities like golf, ballet, or baseball).

You’re more likely to experience symptoms of hip impingement if you have a combination of the factors above (for example, if you were born with an abnormality in your hip joint and also play sports that involve repeated hip movement).

Symptoms of Femoroacetabular Impingement

FAI can develop at any age, but is more common in patients between 20–50 years old. Some common symptoms of hip impingement are:

  • pain in the front of your hip or groin,
  • difficulty walking uphill,
  • a dull ache in the groin, or
  • catching or popping in your hip.

You could experience these symptoms during activities that involve running, jumping, or twisting, as well as after sitting for long periods of time. If you don’t get treatment for this condition, you will continue to feel pain and arthritis and might eventually need a hip replacement.

Diagnosing Hip Impingement

Your doctor will do a physical examination of your hip to check your range of movement and determine the location of your pain. You may also need to have some imaging tests done to confirm the diagnosis, like an X-ray or an MRI scan.

Hip Impingement Treatments

If you’re diagnosed with FAI, your doctor will probably recommend treatment options that don’t require surgery first to see if your symptoms improve. These could include:

  • rest,
  • avoiding activities that make your symptoms worse (running, ballet, golf, and the like),
  • physical therapy exercises to build strength and improve range of motion,
  • anti-inflammatory medications, like ibuprofen or aspirin, or
  • cortisone injections.

These treatments can help relieve your pain, but they won’t fix the structural problems in your bones, so your symptoms might come back. If you have tried treating your symptoms with these options but continue to experience pain, you may need to consider surgery to correct the problems in your joint.

young-athletes-stretching.jpgHip Impingement Surgery

A specialist may recommend surgery if you have symptoms that are painful or affect your ability to participate in daily activities. The goals of surgery for FAI are to improve the function of your hip, decrease painful symptoms, and prevent or delay the need for a hip replacement in the future.

There are a few different options for surgery, depending on what is causing your hip impingement.

  • Arthroscopy

    If you have cam impingement (caused by extra bone growth on your thigh bone) and only mild damage to the cartilage in your joint, you may be a candidate for an arthroscopy. This is a minimally invasive surgery where the surgeon can shape or remove the extra bone and damaged tissue through a small incision in the side of your hip.

  • Osteotomy

    If you have pincer impingement, with the hip socket rotated toward the back, you will need a periacetabular osteotomy. A periacetabular osteotomy, or PAO, cuts and realigns the bone in your hip socket to a more forward-facing position. Your doctor can also remove any extra bone from the top of your thigh bone during this procedure, if needed.

  • Surgical dislocation and osteochondroplasty

    In this procedure, your doctor will make an incision on your hip and carefully cut your thigh bone to bring it out of the joint and provide better access during the rest of the procedure. Then, the head of the thigh bone and the rim of the hip socket can be trimmed or reshaped to fit together properly. After the impingement has been corrected, your doctor will use screws to hold the bone back together.
    This surgery is often used for more complex problems that require full labral reconstruction, or for large deformities like Perthes disease and slipped capital femoral epiphysis (SCFE).

  • Hip replacement (arthroplasty)

    If you have significant damage to the cartilage in your hip joint, you might need to have a total hip replacement. Your doctor will remove the damaged bone and replace the end of your thigh bone as well as the socket of your hip with an artificial joint.

Recovery From Femoroacetabular Impingement Surgery

Recovery from hip impingement surgery will be different for each person and will depend on what type of procedure you have. Most surgeries will require you to use crutches for a few months after your procedure and perform physical therapy exercises to regain strength and range of motion in your joint.

Most patients are able to return to their normal activities within six months, but you should continue to follow up with your doctor to make sure your hip continues to heal properly and symptoms do not return.