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Femoroacetabular Impingement

Person with hands on hips

What is Femoroacetabular Impingement?

Femoroacetabular impingement (FAI) is a condition where abnormal bone growth in the hip joint causes improper contact between the femoral head (ball) and the acetabulum (socket). This irregular fit leads to friction during movement, which can damage the joint structures over time, resulting in pain and reduced mobility.

Understanding Hip Anatomy

The hip joint is a ball-and-socket structure composed of:
  • Acetabulum: The socket, formed by the pelvis, which houses the femoral head.
  • Femoral Head: The ball-shaped upper end of the thigh bone (femur) that fits into the acetabulum.
  • Articular Cartilage: A smooth, protective layer covering the bone surfaces to allow seamless movement.
  • Labrum: A ring of fibrocartilage surrounding the acetabulum, which enhances stability and maintains joint integrity.

Causes of Femoroacetabular Impingement

FAI occurs due to abnormal bone development in the hip joint. Contributing factors include:
  • Structural Abnormalities: Variations in hip joint shape, either congenital or developmental.
  • Repetitive Movements: High-impact activities or sports that involve excessive hip flexion.
  • Previous Hip Injuries: Trauma to the hip can lead to joint irregularities.
  • Underlying Conditions: Diseases like Perthes disease or slipped capital femoral epiphysis (SCFE) can predispose individuals to FAI.

Types of Hip Impingement

FAI is classified into three types:
  • Cam Impingement: The femoral head is misshapen, causing it to grind against the acetabulum.
  • Pincer Impingement: The acetabulum extends excessively over the femoral head, leading to joint compression.
  • Combined Impingement: A combination of both cam and pincer impingement.

Risk Factors for Femoroacetabular Impingement FAI

  • Hip muscle imbalances or weakness.
  • Abnormal hip joint mobility (either too stiff or too flexible).
  • Tight muscles around the hip joint.
  • Previous hip fractures or injuries.
  • Sporting activities that stress the hip joint, particularly during adolescence.

Symptoms of Femoroacetabular Impingement

Individuals with FAI often experience:
  • Hip or groin pain during certain movements.
  • Discomfort extending to the thigh, lower back, or buttocks.
  • Joint stiffness and limited range of motion.
  • Clicking, catching, or locking sensations in the hip.
  • Difficulty walking or engaging in physical activities.

Diagnosis of Femoroacetabular Impingement

A healthcare professional will perform:
  • Physical Examination: Assessing hip pain, movement limitations, and performing the impingement test.
  • X-rays: Identifying bone irregularities and joint wear.
  • MRI Scans: Evaluating soft tissue damage, such as labral tears.

Treatment Options for Femoroacetabular Impingement

Most cases can be managed with non-surgical treatments, while severe cases may require surgery.
Conservative (Non-Surgical) Treatment
  • Activity Modification: Avoiding positions that aggravate symptoms.
  • Pain Management: Using anti-inflammatory medications (as advised by a medical professional).
  • Physiotherapy:
    • Strengthening hip muscles, particularly the gluteal muscles.
    • Stretching to improve flexibility and joint mobility.
    • Balance and proprioception exercises to enhance movement control.
  • Manual Therapy: Hands-on techniques to reduce stiffness and improve mobility.
  • Orthotics and Postural Adjustments: Supporting proper biomechanics and movement patterns.
  • Acupuncture: May help relieve pain and muscle tightness.

Injection Therapy
  • Corticosteroid Injections: Ultrasound-guided injections can temporarily reduce inflammation and pain, aiding rehabilitation.

Surgical Intervention
If conservative treatments are ineffective, surgery may be considered:
  • Hip Arthroscopy: A minimally invasive procedure where the surgeon removes excess bone and repairs damaged cartilage or labral tears.
  • Open Surgery: In severe cases, a larger incision may be needed to reshape the hip joint more extensively.

Prognosis and Prevention

With early intervention, most individuals recover well and can return to normal activities. Preventive measures include:
  • Maintaining strong and flexible hip muscles.
  • Using proper techniques during sports and physical activities.
  • Avoiding repetitive stress on the hip joint.
  • Seeking early medical advice if symptoms arise.
FAI treatment aims to relieve pain, improve function, and prevent long-term complications such as arthritis. If you experience persistent hip pain, consult a healthcare professional for a tailored treatment plan.

Further information

Last updated24 Apr 2025