Hip Impingement (FAI)

What is Femoro-acetabular Impingement (FAI)?

Femoro-acetabular impingement (FAI) happens when extra bone grows on the hip joint. This can be on the thigh bone (femur) or the hip socket (acetabulum). The extra bone can make the joint rub against each other, which can cause pain and stiffness over time.

There are three types of FAI:

1. Cam impingement – Extra bone grows on the femur, making it less round and causing it to press against the hip socket.
2. Pincer impingement – Extra bone grows on the hip socket, covering too much of the femur and pinching the cartilage.
3. Combined impingement – A mix of both cam and pincer types.

Why does it occur?

FAI can happen for different reasons, such as:

1. Bone Growth During Childhood
   • Some people naturally grow extra bone on their hip joint as they get older.
   • Genetics might play a role in this.
2. Sports and Repetitive Movements
   • Sports like football, hockey, dancing, and martial arts involve a lot of hip movement, which can lead to extra bone growth.
   • Young athletes training a lot may be at higher risk.
3. Injuries or Hip Conditions
   • Injuries or conditions like hip dysplasia (where the hip socket doesn’t fully cover the ball portion of the upper thigh bone) can affect how the hip develops.
   • Small, repeated injuries may cause extra bone to grow.
4. Genetics
   • Some people are born with a hip shape that makes them more likely to develop FAI.
5. Wear and Tear
   • Over time, the rubbing of bones can cause damage, like cartilage breakdown or arthritis.

What are the symptoms?

FAI symptoms can be different for each person, but common ones include:

1. Hip Pain (Most Common Symptom)
   • Usually in the groin area, but also in the outer hip, thigh, or buttocks.
   • Pain typically starts mild and gets worse over time.
   • Can feel sharp with movement or like a dull ache after sitting or activity.
2. Stiffness and Less Movement
   • Harder to bend the hip fully (for example, squatting, tying shoes, or getting in/out of a car).
   • Feeling of tightness, especially with deep bending.
3. Clicking, Catching, or Locking
   • The hip might "catch" or "lock" when moving. This could be due to damage in the cartilage.
4. Pain with Certain Movements
   • Pain can happen when bending, twisting, or playing sports.
   • Movements like deep squats or sitting cross-legged may be uncomfortable.
5. Weakness or Instability
   • The hip might feel like it’s "giving way."
   • Standing on one leg may be difficult.

How common is it?

Among people with hip pain, around 30-50% have FAI. In athletes (such as dancers and hockey players), up to 90% may have cam-type FAI. It is important to understand that just because a person has an FAI, it does not mean they will have symptoms.

• Teenagers who play sports are more likely to develop FAI.
• Women are more likely to have pincer-type FAI, while men are more likely to have cam-type.

How long does it last?

FAI is a condition that does not go away on its own, but treatment can help manage the symptoms. Treatment options include:

• Physiotherapy – Exercises to strengthen the hip and improve movement.
• Activity Modification – Avoiding certain movements that cause pain.
• Painkillers – Medicines like paracetamol can help reduce pain.
• Surgery – If symptoms do not improve, an operation may be needed.

Taking painkillers

Taking painkillers like paracetamol help to reduce pain. Non-steroid anti-inflammatory drugs (NSAIDs) are also available as gels or creams. Discuss taking painkillers, using NSAID gels or creams with your pharmacist or GP.

Activity modification

Some movements may make FAI worse. It can help to avoid:

• Deep squats (like sumo squats)
• High knees
• Lunges
• Leg press
• Deadlifts
• Jumping exercises (for example, high box jumps)
• Rowing machines
• Plyometric exercises (for example, squat-jacks)

Instead, try low-impact exercises like swimming.

Will I require an operation?

Not everyone needs surgery. Many people manage their symptoms with conservative treatment alone. However, if symptoms do not improve, surgery may be an option.

George Eliot Hospital is a smoke free environment. For help and advice to stop smoking you can call the national helpline on 0300 123 1044 or visit https://fitterfutures.everyonehealth.co.uk/stop-smoking-service/ ​​​​​​. You can also call the local telephone number for the Warwickshire service on 0333 005 0092 or Coventry service on 0800 112 3780.

Copyright

Except where otherwise noted, this item is licensed under the CC BY license (https://creativecommons.org/licenses/by/4.0/)

If you are a rights holder and are concerned that you have found material on our patient information resources website, for which you have not given permission, or is not covered by a limitation or exception in national law, please contact us using the Feedback form providing your contact information and full details of the material.