Sports MedicineHipSurgery Center

FAI Correction (Femoroacetabular Impingement)

Performed by John Christoforetti, MD, a fellowship-trained hip preservation specialist, FAI correction at MOS uses arthroscopic bone reshaping (osteoplasty) to address the mechanical root cause of hip impingement — cam lesion, pincer lesion, or both.

Duration: 75–120 minutesAnesthesia: General with nerve block

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What is fai correction (femoroacetabular impingement)?

FAI correction is an arthroscopic surgical procedure that reshapes abnormal bone at the hip joint — either a cam lesion (bump on the femoral head-neck junction) or a pincer lesion (overcoverage of the acetabular rim) — to eliminate the impingement that is tearing the labrum and damaging cartilage. It is typically performed at the same time as labral repair.

Why this approach — at MOS

FAI correction requires more than removing bone — it demands precise surgical judgment about how much to remove, where to remove it, and how to confirm adequacy without over-resecting. Removing too little bone leaves the impingement unresolved; removing too much risks femoral neck fracture or joint instability.

Dr. Christoforetti's approach to cam correction is based on pre-operative alpha angle measurement, intraoperative fluoroscopic guidance, and a dynamic assessment of hip motion after osteoplasty — moving the hip through its full range under arthroscopic visualization to confirm impingement is eliminated. This dynamic exam under anesthesia is a critical quality step that confirms the adequacy of bone reshaping in a way that static imaging cannot.

For pincer lesions, rim trimming is selective: the amount removed is guided by the degree of overcoverage and the patient's acetabular anatomy. Excessive pincer resection can destabilize the hip; under-resection leaves the problem unaddressed. The capsule is repaired routinely, as capsular integrity is important for long-term joint stability.

The evidence supports combined labral and capsular management as the key to durable outcomes. Long-term follow-up data from multiple centers confirm that femoral osteoplasty combined with labral repair substantially improves joint survivorship compared to addressing the labrum alone — validating the philosophy that the bone problem must be fixed along with the soft tissue problem.

Patients seen at our Bethesda and Germantown offices undergo a thorough pre-operative consultation to review imaging, discuss operative goals, and set realistic expectations before any surgical plan is finalized.

Who is a candidate?

Indications

Cam morphology (elevated alpha angle, typically > 55°) with labral tear or chondral damage confirmed on MRI arthrogram
Pincer morphology (lateral center-edge angle > 40° or acetabular retroversion) with labral impingement
Mixed cam-pincer FAI with symptomatic intra-articular pathology
Hip pain with a positive impingement test (flexion-adduction-internal rotation, or FADIR), worsened by sitting or athletic activity
Failed 3–6 months of non-operative management including physical therapy and injections
Adequate joint space (Tönnis grade 0–2) indicating the hip can benefit from joint preservation

Contraindications

Advanced osteoarthritis (Tönnis grade 3 or near-complete joint space loss) — bone reshaping cannot restore a joint that has lost its cartilage
Significant hip dysplasia (lateral center-edge angle < 20°) — these hips may need periacetabular osteotomy before or instead of arthroscopic FAI correction
Patients unwilling to commit to post-operative rehabilitation
Severe medical comorbidities precluding surgery
Active infection

Conservative Treatment First

Not all hip pain from FAI requires surgery. Before recommending osteoplasty, a structured conservative program is completed. This includes dedicated physical therapy focused on hip flexor stretching, external rotator strengthening, core stability, and movement pattern correction to reduce impingement during daily activities. NSAIDs reduce inflammatory pain. An intra-articular cortisone injection under ultrasound or fluoroscopic guidance confirms that the pain is coming from inside the joint and may provide months of temporary relief.

If pain persists despite 3–6 months of this approach and imaging confirms structural damage (torn labrum, chondral injury), surgical correction of the bony impingement combined with labral repair offers the best chance of restoring hip function and preventing further joint damage.

The procedure

What Is FAI Correction?

Femoroacetabular impingement (FAI) is a condition in which the bones of the hip joint have an abnormal shape, causing them to pinch — or "impinge" — against each other during motion. Over time, this mechanical conflict tears the labrum and erodes articular cartilage, leading to pain, reduced range of motion, and, if left untreated, progressive joint damage.

There are two main types of FAI. A cam lesion is a bony prominence on the femoral head-neck junction — the zone where the ball of the hip meets the neck of the femur. A normal femoral head is perfectly spherical. In cam FAI, the head is aspherical (not round), and this bump jams into the acetabular socket and labrum when the hip flexes and rotates. A pincer lesion is excess bone on the rim of the acetabular socket, causing the rim to overcover the femoral head. The prominent rim digs into the femoral neck and crushes the labrum between bone and neck. Most patients have a combination of both — called mixed FAI.

FAI is not simply a finding on imaging. Many people have bony morphology consistent with FAI but no symptoms. Surgery is considered only when the bony impingement is causing documented labral or chondral injury and symptoms that have failed non-operative management.

FAI correction does not simply address the labrum — it addresses the underlying mechanical reason the labrum is being torn. Without correcting the bone, labral repairs are more likely to fail because the same abnormal mechanical forces continue to act on the repaired tissue.

What Happens During FAI Correction?

Pre-Operative Planning Before surgery, Dr. Christoforetti reviews standing AP pelvis and lateral hip X-rays, MRI arthrogram findings, and patient-specific anatomy. The alpha angle (a measure of cam lesion severity) is measured precisely. The amount of bone to remove is planned in advance. Fluoroscopy is used intraoperatively to confirm the adequacy of bone resection.

Anesthesia and Positioning FAI correction is performed under general anesthesia combined with a peripheral nerve block for post-operative pain control. The patient is positioned on a specialized hip arthroscopy traction table. Controlled traction is applied to the operative leg to open the hip joint.

Central Compartment: Labral Work The surgeon first enters the central compartment (inside the joint) and performs a complete diagnostic inspection. Labral tears are repaired with suture anchors. Chondral damage is addressed. Loose bodies are removed. Any acetabular rim osteoplasty needed for pincer correction is performed from this perspective.

Peripheral Compartment: Femoral Osteoplasty Traction is then released and the peripheral compartment is entered. This is where femoral osteoplasty (cam correction) is performed. Using a high-speed motorized burr under both arthroscopic and fluoroscopic visualization, the surgeon carefully reshapes the femoral head-neck junction — removing the cam bump and restoring a smooth, concave contour. Fluoroscopy confirms that the resection is adequate and that no more than the safe maximum of bone has been removed (over-resection can weaken the femoral neck).

A dynamic examination is then performed: the hip is moved through flexion and rotation under direct visualization to confirm that impingement has been fully eliminated and that the labrum moves freely without pinching.

Capsular Closure The hip capsule is repaired after the instruments are removed. Capsular closure restores stability and reduces the risk of iatrogenic hip instability.

Closure Portal sites are closed with sutures. Total operative time is typically 75–120 minutes depending on the complexity of the bony correction and associated intra-articular work.

Recovery timeline

Days 1–14 (Protected Weight-Bearing)

Crutches are required. Weight-bearing is limited to allow femoral neck bone healing at the osteoplasty site and to protect the labral repair. Ice and elevation reduce swelling. Nerve block provides initial pain control.

Weeks 2–6 (Early Therapy)

Physical therapy begins. Gentle range-of-motion, soft tissue mobilization, and progressive weight-bearing as tolerated. No hip flexion past 90° or forced rotation during the healing phase.

Weeks 6–12 (Strengthening Phase)

Hip abductor, external rotator, and core strengthening progress. Stationary cycling is added. Impact activities remain restricted.

Months 3–5 (Return to Activity)

Running, sports-specific training, and pivoting movements are reintroduced gradually as strength and neuromuscular control improve.

6 Months (Return to Full Sport)

Most patients cleared for full unrestricted activity at 5–6 months. Competitive athletes may require slightly longer based on sport demands.

FAI correction with labral repair requires a longer protected phase than labral-only work because the osteoplasty site on the femoral neck must heal. Patients are instructed to avoid deep hip flexion (past 90°) and aggressive rotation for the first 6 weeks. Physical therapy progresses through distinct phases aligned with healing biology.

MOS physical therapists work closely with Dr. Christoforetti and understand the specific precautions for FAI correction. The nerve block placed before surgery helps patients tolerate the first 12–18 hours more comfortably. Most patients are pleasantly surprised by how manageable the first few days are with appropriate pain management and ice therapy. The discipline of the first 6 weeks largely determines the quality of the long-term result.

Frequently Asked Questions

What is the difference between a cam lesion and a pincer lesion?

A cam lesion is a bony bump on the femoral head (the "ball") at the point where it transitions to the neck. This bump scrapes and crushes the labrum and cartilage during hip flexion and internal rotation. A pincer lesion is excess bone on the acetabular rim (the "socket"), causing the rim to overcover the femoral head. Both cause labral damage, but through different mechanical mechanisms. Most patients with FAI have elements of both — this is called mixed FAI.

Does FAI correction always require labral repair at the same time?

Almost always. FAI is the mechanical reason the labrum tears. If you repair the labrum without fixing the bone impingement, the same forces that tore the labrum will continue to act on the repair. Conversely, correcting the bone without addressing the torn labrum leaves the joint without a properly functioning seal. In the majority of cases, both are addressed during the same procedure.

How is the amount of bone removed determined?

The amount of bone removed during femoral osteoplasty is guided by three things: pre-operative alpha angle measurement on X-ray and MRI, real-time fluoroscopic confirmation during surgery, and a dynamic hip motion assessment under anesthesia after the resection is complete. The goal is to restore a smooth, spherical femoral head without removing more than 30% of the femoral neck circumference (beyond which fracture risk increases).

Is FAI correction an open or minimally invasive procedure?

At MOS, FAI correction is performed arthroscopically — through 2 or 3 small incisions roughly the diameter of a pencil. This eliminates the need for the larger incisions and muscle detachment required with open hip surgery, allowing same-day discharge and faster recovery.

How long before I know if the surgery worked?

Significant improvement in pain is usually felt within 6–12 weeks, though the hip continues to heal and improve for 6–12 months. Many patients note that the deep groin pain with sitting resolves earlier, while athletic performance and full strength return more gradually. Patience with the rehabilitation process is essential.

What if my FAI is not treated?

Untreated FAI causes cumulative damage to the labrum and articular cartilage each time the hip moves through impingement range. Over years, this can lead to progressive osteoarthritis. The degree to which FAI accelerates arthritis depends on the severity of the morphology, activity level, and individual factors. Not everyone with FAI develops severe arthritis, but the risk is real — particularly in patients who continue high-impact activity with symptomatic impingement.

Can FAI come back after surgery?

FAI correction permanently reshapes the bone. The bony morphology does not return. However, if the initial resection was inadequate (residual cam or pincer), symptoms may persist or recur — which is one reason intraoperative fluoroscopy and dynamic assessment are so important. Labral re-tears can also occur if the hip is subjected to significant trauma.

Related conditions

Hip Labral Tear & Femoroacetabular Impingement (FAI)

Medically reviewed by John J. Christoforetti, MD, MD, FAAOS

Last reviewed May 20, 2026