Femoroacetabular Impingement (FAI) is a condition characterized by excessive friction within the hip joint due to irregular bony structures, leading to pain and reduced hip motion range. The interaction between the femoral head and acetabulum causes damage and discomfort in the hip joint. This damage commonly affects the articular cartilage (the smooth surface of the ball or socket) or the labral tissue (the lining of the socket’s edge) during regular hip movements. Repeated friction can result in the fraying or tearing of the articular cartilage or labral tissue. Over time, the loss of cartilage and labrum progresses until the femur bone and acetabulum bone make direct contact, leading to bone-on-bone friction, often known as Osteoarthritis.
FAI typically presents in two forms: Cam and Pincer.
CAM Impingement: Cam impingement occurs when the femoral head and neck lack perfect roundness, often due to excessive bone formation, leading to abnormal contact between surfaces.
PINCER Impingement: Pincer impingement involves an overgrown acetabulum rim or socket that is excessively deep, covering too much of the femoral head. This situation often results in pinching of the labral cartilage. Pincer impingement may also occur when the hip socket is angled abnormally backward, causing unusual contact between the femoral head and the acetabulum rim.
Most FAI diagnoses involve a combination of Cam and Pincer forms.

Symptoms of FAI

Symptoms of femoroacetabular impingement can manifest as follows:
  • Groin pain during hip activity
  • Pain in the front, side, or back of the hip
  • Pain characterized as dull ache or sharp pain
  • Sensations of locking, clicking, or catching in the hip
  • Pain in the inner hip or groin area after prolonged sitting or walking
  • Difficulty walking uphill
  • Restricted hip movement
  • Lower back pain
  • Pain in the buttocks or outer thigh area

Diagnosis

Evaluation of hip conditions requires assessment by an orthopedic hip surgeon for accurate diagnosis and treatment.
  • Medical History
  • Physical Examination
  • Diagnostic studies including X-rays, MRI scans, and CT scans

Risk Factors

Several factors increase the likelihood of developing femoroacetabular impingement:
  • Participation in sports like football, weightlifting, and hockey
  • Engaging in heavy labor
  • Repetitive hip flexion
  • Congenital hip dislocation
  • Anatomical abnormalities of the femoral head or hip angle
  • Legg-Calves-Perthes disease, a childhood arthritis causing bone breakdown due to impaired blood supply
  • Hip trauma
  • Inflammatory arthritis

Treatment Options

Treatment options for FAI include conservative and surgical approaches:
Conservative measures aim to manage symptoms without surgery but may not address the underlying hip biomechanics causing FAI:
  • Rest
  • Activity modification and limitations
  • Anti-inflammatory medications
  • Physical therapy
  • Injection of steroids and analgesics into the hip joint
Surgical treatment, such as hip arthroscopy, becomes necessary when conservative measures fail to alleviate symptoms.
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