Hip Impingement (FAI)

Hip impingement, or FAI (femoroacetabular impingement), is a structural problem in which extra bone on the ball or rim of the hip joint catches against the opposite surface during movement instead of gliding smoothly. The extra bone can sit on the ball (a cam shape), on the socket rim (a pincer shape), or both. Each time it catches, it stresses the labrum and the cartilage beneath it, and that damage is cumulative. The bone shape cannot be changed without surgery, but the pain and irritation it causes can often be managed, especially when addressed early.

Common symptoms include:

• A deep ache in the front of the groin
• Pain with deep bending, such as getting in and out of a low car, squatting, or sitting cross-legged
• Stiffness for the first few steps after sitting for a long time
• A catching or clicking sensation deep in the joint, especially with pivoting
• Gradual loss of hip motion, particularly flexion and inward rotation

Your provider performs a focused exam, and bringing the hip into flexion with inward rotation, the position where the cam or pincer catches, usually reproduces the deep groin pain. Standing X-rays show the bony contour and can reveal the cam bump or pincer overhang. MR arthrography, an MRI taken after contrast is injected into the joint, highlights the labrum and cartilage when more detail is needed.

Most patients begin with nonsurgical care aimed at reducing how often the joint catches:

• Activity changes to cut back on deep hip bending, low seating, and high-impact running
• Physical therapy to strengthen the deep hip rotators and core and retrain hip mechanics
• Anti-inflammatory medication to interrupt the pain-inflammation cycle
• A corticosteroid injection to calm inflammation and help confirm the hip is the source of pain

Surgery is considered when a labral tear is confirmed, pain has not improved after a genuine trial of nonsurgical care, and you want to return to activities the hip now limits. The procedure is a hip arthroscopy that reshapes the cam or pincer and repairs or trims the torn labrum.

For a fuller explanation, including anatomy, diagnosis, and the full range of treatment:

• Femoroacetabular Impingement — AAOS OrthoInfo