Femoroacetabular Impingement (FAI)
Femoroacetabular impingement (FAI) is a condition where abnormal bone growth on the femoral head (cam impingement), the acetabular rim (pincer impingement), or both causes friction inside the hip joint during movement. The extra bone grinds against the labrum and cartilage, progressively damaging the joint. It is one of the most common causes of hip pain in active young and middle-aged adults, and a leading reason for early-onset hip arthritis if untreated.
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Symptoms
- Groin pain or deep hip pain during or after activity
- Pain after prolonged sitting (the "C-sign": gripping the outer hip like a C)
- Reduced hip range of motion, especially internal rotation and flexion
- A clicking, catching, or locking sensation in the hip
- Pain with hip flexion activities like squatting, cycling, or tying shoes
- Dull ache in the outer hip or buttock
When to See a Doctor
See an orthopaedic hip specialist if hip or groin pain limits activity, persists beyond 6 weeks, or is accompanied by catching. An X-ray identifies bony abnormalities; an MRI arthrogram visualizes labral tears. FAI is frequently missed for years. If your pain sits in the groin and worsens with flexion, ask about impingement specifically.
Treatment Options
Activity modification and physical therapy
First-line treatment. Avoiding provocative positions combined with hip strengthening and range-of-motion work can reduce symptoms significantly in early-stage disease.
Intra-articular injection
Corticosteroid injection provides temporary pain relief and is useful both diagnostically (confirming the hip is the pain source) and therapeutically. Not a long-term solution.
Hip arthroscopy
Minimally invasive surgery that reshapes the bone abnormality (osteoplasty), repairs the labrum, and addresses any cartilage damage. Appropriate when conservative treatment fails and the joint is not severely arthritic.
Total hip replacement
For patients with FAI that has progressed to end-stage hip arthritis. Hip arthroscopy is not appropriate once significant cartilage loss has occurred.
Recovery Timeline
Physical therapy: 3-6 months for symptom improvement. Hip arthroscopy: return to sport by 4-6 months; full recovery by 9-12 months. Early treatment before cartilage wears out produces significantly better outcomes.
Frequently Asked Questions
What causes femoroacetabular impingement?
FAI is largely structural. The bone shape develops abnormally during skeletal growth, often in people who were highly active in youth while their growth plates were still open. Cam impingement (a bump on the femoral head) is more common in young athletic males; pincer impingement (overcoverage of the socket) is more common in middle-aged women. There is a clear genetic component. Having a parent with FAI significantly increases your risk.
Can FAI be treated without surgery?
Yes, in many cases. Physical therapy focused on hip strengthening and posture modification, combined with activity changes to avoid provocative positions, can manage symptoms well for extended periods. Surgery is considered when conservative treatment fails after 3-6 months, not as a first step. Some patients with FAI never require surgery at all.
Does FAI always lead to hip replacement?
Not necessarily. If FAI is caught before significant cartilage damage occurs, hip arthroscopy can reshape the bone, repair the labrum, and preserve the natural joint for many years. If arthritis is already advanced, hip replacement becomes necessary. Early diagnosis and treatment are key to avoiding joint replacement.
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This information is for educational purposes only and is not a substitute for professional medical advice. Always consult a qualified healthcare provider for diagnosis and treatment.