Femoroacetabular Impingement


Femoroacetabular Impingement, Hip Impingement, FAI

  • Definitions
  1. Femoroacetabular Impingement (FAI)
    1. Abutment of the acetabular rim against the proximal femur
  • Epidemiology
  1. Common cause of Hip Pain
  2. Earlier presentations in athletes than non-athletes
    1. Athletes often present with less bony changes on plain film imaging than non-athletes
    2. More common presentations in athletes requiring hip hyperflexion and wide range of motion
  • Types
  1. Cam Deformity
    1. Bony overgrowth of femoral neck or femoral head
  2. Pincer Deformity
    1. Overgrowth of the acetabulum
  • Symptoms
  1. Gradual onset without history of specific injury
  2. Anterolateral Hip Pain
    1. Sharp pain
    2. Gradual progression
    3. Limits both sport activities as well as simple Activities of Daily Living
    4. C-Sign used by patients to demonstrate the area of pain (esp. with labral tear)
      1. Patient cups the area of pain between their thumb and index finger
      2. C-Shape: One finger on anterior hip and the other on posterior hip (below the inguinal ligament)
  3. Provocative maneuvers
    1. Hip flexion and Hip Rotation
    2. Deep Squat
    3. Turning or pivoting toward the affected side
    4. Prolonged sitting
    5. Rising from a chair or getting in or out of a car
    6. Forward flexion
  • Signs
  1. See Hip Exam
  2. FADIR Test (specific for Hip Impingement)
  • Imaging
  • XRay
  1. Anteroposterior Hip
    1. Hip Osteoarthritis
    2. Acetabulum dysplasia
    3. Osteonecrosis of femoral head
    4. Sacroiliac joint Osteoarthritis
    5. Lumbar Spine disorders
  2. Standing Anteroposterior Hip
    1. Best identifies Pincer Deformity
  3. Dunn View (hip flexed to 90 degrees and abducted 20 degrees)
    1. Anterior femoral neck Cam lesion (exostosis predisposing to FAI by impinging labrum against acetabulum)
    2. Anterior femoral neck osteophytes
  • Imaging
  • Advanced
  1. MRI hip with arthrography (contrast)
    1. Evaluates the hip labrum with Test Sensitivity >90% (<30% without arthrography)
    2. Diagnostic bupivicaine (Marcaine) injection at the time of arthrography can assist diagnosis
      1. Patient keeps diary of pain level following injection
      2. Improvement in pain following injection suggests intraarticular cause of pain
  • Differential Diagnosis
  • Management
  1. Physical Therapy
    1. Goal to improve hip Muscle flexibility and strength
  2. Orthopedic referral
    1. Hip Pain refractory to conservative measures
    2. Arthroscopy
      1. Goal to reduce impingement and Osteoarthritis risk, and to repair or remove injured tissue
      2. Most beneficial in hip locking, catching or popping or for sharp Hip Pain