Hip Impingement (FAI)

Hip impingement, sometimes called FAI (for femoroacetabular impingement), is when extra bone on the ball or rim of your hip joint catches and grinds during movement instead of gliding smoothly. The bumpy edge can sit on the ball at the top of your femur (a cam deformity), on the rim of the socket in your pelvis (a pincer deformity), or both. Each time the bone catches, it tears the labrum, the cartilage seal around the socket, and gradually wears down the smooth cartilage underneath.

Hip impingement is one of the most common causes of hip pain in active adults in their 20s through 40s. The unusual bone shape is often something you were born with; the pain only shows up later, when increased demand from sport, sustained sitting, or certain occupations starts irritating the tissue. Left alone, the labral tear and cartilage damage tend to progress, and can speed up the development of hip arthritis.

The hallmark of hip impingement is a deep ache in the front of your groin. Patients often cup a hand in a C-shape around the hip crease to show where it hurts, a gesture orthopedists call the "C sign." The pain comes on with deep bending: getting in and out of a car, squatting, sitting cross-legged, or any movement that drives the femur up into the socket. After sitting for a while, the hip feels locked up for the first few steps when you stand.

You may also notice a catching or clicking sensation deep in the joint, especially when you pivot or twist. Athletic activity, running, cutting sports, and kicking tend to flare the pain, and you may realize you cannot flex the hip as far or rotate it inward the way you used to. Over time the symptoms become more frequent and take longer to settle, a sign that the labrum and cartilage are accumulating damage.

Your provider performs a focused physical exam of the hip; if it reproduces your deep groin pain, it is a strong sign of impingement. Standing X-rays show the bony bumps on the ball or socket. The gold-standard imaging study is MR arthrography, an MRI taken after contrast is injected directly into the hip joint to highlight the labrum and cartilage.

Most patients start with non-surgical care aimed at calming the irritated tissue and taking load off the joint. The steps below are the ones we usually introduce first, in the order we reach for them.

1. Activity Modification

   Cutting back on the activities that drive deep bending of the hip (deep squats, prolonged sitting, high-impact running) reduces how often the joint catches and lets the irritated tissue calm down.

2. Physical Therapy

   Targeted strengthening of the deep hip rotators and the core, along with retraining how you move (squat technique, hip mechanics during sport), reduces how hard the bones impinge on each pass.

3. NSAIDs

   NSAIDs like ibuprofen or naproxen interrupt the pain-inflammation cycle around the irritated joint.

4. Intra-Articular Injection

   A corticosteroid injection placed into the hip joint, guided in real time by X-ray or ultrasound, can give months of relief and also confirms the hip itself is the pain source before any surgical conversation.

Surgery is considered when a labral tear is confirmed on imaging, when pain has not improved after a real trial of non-operative care, and when you want to return to activities the hip is keeping you from. The procedure, hip arthroscopy, reshapes the bony bumps on the ball or socket and repairs or trims the torn labrum through small incisions, removing the source of the catching so the joint can glide smoothly again.

External patient-education references and related OSI pages for additional background:

• AAOS OrthoInfo, patient education library
• OSI glossary, orthopedic terminology in plain language