Hip (Femoroacetabular) Impingement

What is hip impingement?

Hip impingement happens when the bones in your hip don’t fit together as smoothly as they should and rub together.

Your hip joint is where the round ball-shaped head of your femur (thigh bone) fits into a socket in your pelvis (acetabulum). That’s where hip impingement gets its medical name: femoroacetabular impingement (FAI).

Femoroacetabular means something related to where your femur fits into the acetabulum. “Impingement” is the medical term for pinching or rubbing together inside a joint. Healthcare providers might call femoroacetabular impingement FAI or hip impingement syndrome.

Femoroacetabular impingement is painful and can make it hard to walk or move. You might feel stiff or sore all the time on one side. Over time, the impingement can damage the cartilage that cushions your hip joint.

Visit a healthcare provider if you’re experiencing hip pain, stiffness or other symptoms that don’t get better in a week or two.

What are hip impingement symptoms?

The most common hip impingement symptoms include:

• Hip pain.
• Stiffness.
• Limping or trouble moving.

Some people with FAI never experience symptoms. But many people notice worsening symptoms the longer they live with hip impingement, especially if it damages the cartilage in their hip joint.

What does femoroacetabular impingement feel like?

Hip impingement usually feels like a constant, dull ache in your hip. It might spread (radiate) to areas around your hip like your groin, butt or thigh. Some people with hip impingement say the pain feels like they have a bruise deep inside their body that someone is constantly pressing on.

FAI pain typically gets worse during physical activities, especially if you’re doing motions that put a lot of stress on your hips (like squatting, lunging or jumping). Lying on your side or sitting still for a long time can also make the pain worse. These activities or positions can make the pain feel sharp or stabbing.

What causes hip impingement syndrome?

Femoroacetabular impingement happens when the bones in your hip joint rub, catch or put extra pressure on each other. It’s usually because of a bone spur on your femur or in your acetabulum. Most people are born with these unusually shaped joints, or naturally develop a bone spur over time.

Types of hip impingement

Healthcare providers classify hip impingement into three types, based on where or why the parts of your hip joint don’t fit together smoothly:

• Cam impingement: This happens when extra bone grows on the head of your femur.
• Pincer impingement: This is extra bony growth in the hip socket.
• Combined impingement: Some people have cam and pincer impingement at the same time.

Hip impingement risk factors

Anyone can be born with or develop hip joints that have impingement. Males are more likely to have cam impingement, while females are more likely to have pincer or combined impingement.

Athletes are more likely to experience hip impingement symptoms, especially if they play sports that put lots of pressure on their hips.

Some studies have found that more than half of athletes have impingement. This doesn’t mean that people who play sports are that much more likely to develop impingement, but that they’re more likely to notice symptoms because they use their hips more often and more intensely than most people. FAI happens because of your natural hip shape, and playing a sport can’t change that.

What are the complications of hip impingement?

Without treatment, FAI can damage your hip joint over time. In addition to worsening symptoms that make it harder to move or use your hip, the impingement can tear the labrum in your affected hip. The labrum is a rim of cartilage that lines your hip socket. The extra pressure and friction from femoroacetabular impingement can gouge the labrum until it tears.

People with hip impingement are also more likely to develop osteoarthritis in that hip if the impingement wears down their cartilage over a long time.

How do healthcare providers diagnose hip impingement?

A healthcare provider will diagnose hip impingement syndrome with a physical exam and imaging tests. Tell your provider when you first noticed symptoms and if any movements, activities or positions make the symptoms worse (or better).

Your provider will use imaging tests to take pictures of your hip and the tissue inside and around your joint. These tests may include:

• Hip X-ray.
• MRI.
• CT scan.

Your provider may inject a small amount of local anesthetic into your hip to numb it. If the medication temporarily relieves pain or stiffness, it can be a sign you have FAI. They may use other medications to manage hip impingement, but this is usually a good way to help diagnose it.

Hip impingement test

A femoroacetabular impingement test is a series of physical movements and positions to help your provider check for impingement in your hip. You’ll lie on your back and your provider will lift your leg up toward your chest. Then, with your knee bent 90 degrees (perpendicular to your thigh), they’ll twist your upper leg in, toward the center of your body.

These positions help your provider put light pressure on your hip in the places where you might have FAI. If you feel pain at any point during these movements, you might have hip impingement. The test may be uncomfortable, but it’s safe. Tell your provider if any part of the test causes severe pain.

What are hip impingement treatments?

Your provider will suggest a combination of treatments that manage your symptoms and prevent further damage inside your hip. Common hip treatments include:

• NSAIDs: Over-the-counter NSAIDs reduce inflammation and relieve pain.
• Corticosteroids: Corticosteroids are prescription anti-inflammatory medications. Your provider may give you a cortisone shot directly into your hip joint.
• Physical therapy: Physical therapy will help you strengthen the muscles around your affected hip. This can relieve pressure on your hip joint and improve your ability to move.
• Activity modification: You might be able to change how you exercise or avoid certain movements that make hip impingement pain worse.
• Surgery: Your provider will suggest surgery if you have severe symptoms that affect your quality of life or if nonsurgical treatments haven’t worked. You might need surgery if you have a hip labral tear. Hip arthroscopy is the most common surgery to repair hip impingement. Your surgeon will tell you what to expect.

Will hip impingement go away?

Hip impingement syndrome won’t go away unless you have surgery to correct the shape of your hip. But most people with FAI can manage symptoms with nonsurgical treatments.

You might find that nonsurgical treatments become less effective over time. Talk to your provider or surgeon about which treatments are right for you, and when it’s right to consider surgery.

Hip arthroscopy to repair femoroacetabular impingement has a very high success rate, and many people have no long-term side effects. You might have to avoid or modify certain exercises or types of movements, but you should still be able to stay active, including playing sports.

Can I prevent FAI?

You can’t prevent hip impingement because it’s caused by the natural shape and alignment of your hip joint. Treating impingement as soon as possible is the best way to help prevent complications like hip labral tears.

When should I see my healthcare provider?

Visit a healthcare provider if you’re experiencing hip pain or stiffness or have trouble moving or using one of your hips — especially if these symptoms last for more than a few weeks.

Tell your provider if treatments like NSAIDs or physical therapy don’t seem to be working as well as they used to.

Which questions should I ask my provider?

• Which type of hip impingement do I have?
• When should I consider surgery?
• Which activities or hip movements should I avoid?
• Do I have an increased risk of a hip labral tear?