Femoroacetabular Impingement (FAI): What You Need to Know

What Is FAI?

Femoroacetabular impingement (FAI) is a condition in which extra bone grows along the surfaces of the hip joint, either on the femoral head (called a CAM lesion) or on the acetabular rim (called a Pincer lesion), or both. This extra bone creates abnormal contact and friction during hip movement, which can damage the cartilage and labrum over time.

Types of FAI

CAM impingement involves an abnormal bump on the femoral head/neck junction. It is more common in young athletic males and causes damage to the cartilage and labrum inside the socket.
Pincer impingement involves over-coverage of the femoral head by the acetabulum. It is more common in middle-aged women and causes repeated contact between the labrum and the femoral neck.
Combined CAM and Pincer impingement is the most common pattern.

Symptoms

• Deep groin pain, often described as an ache
• Pain with sitting for prolonged periods
• Restricted range of hip movement, particularly internal rotation
• A sharp catching pain with flexion and rotation activities (tying shoelaces, pivoting in sport)
• Pain at the end-range of hip flexion

Who Is Affected?

FAI is most common in young to middle-aged adults who are physically active. Athletes involved in sports requiring repeated hip flexion (football, hockey, martial arts, cycling) are particularly at risk. FAI is increasingly recognised as a cause of groin pain in athletes.

Diagnosis

Diagnosis is based on symptoms, clinical examination findings, and imaging. Plain X-rays identify the bony morphology. MRI arthrography provides detail on associated labral tears and cartilage damage. The FADIR provocation test is frequently positive.

Treatment

Non-operative treatment includes activity modification, physiotherapy (hip stabiliser strengthening, avoiding impingement positions), and corticosteroid injections for pain relief.

If symptoms fail to settle, hip arthroscopy is the preferred surgical option. The surgeon trims the excess bone (osteoplasty) and repairs any associated labral tear. Early intervention before significant cartilage damage develops leads to the best outcomes.