What does the Faber test screen for?

What Does the FABER Test Screen For?

The FABER (Flexion-Abduction-External Rotation) test primarily screens for hip joint pathology, including femoroacetabular impingement (FAI), labral tears, and other intra-articular hip conditions, with its greatest clinical utility being to rule out hip disease when negative rather than to confirm it when positive. 1, 2

Primary Diagnostic Applications

Hip Joint Pathology Detection

• The FABER test is used to assess for hip-related pain in young and middle-aged active adults, particularly screening for FAI syndrome, acetabular dysplasia, hip instability, and labral pathology 1, 2
• A negative FABER test helps rule out hip disease with high sensitivity, making it most valuable for excluding hip pathology rather than confirming it 2
• The test demonstrates high sensitivity but low specificity, meaning a positive test may indicate hip pathology but requires further evaluation 2

Specific Pathological Correlations

• A positive FABER test is associated with higher alpha angles in symptomatic patients, with an average alpha angle of 74° in positive tests compared to 68° in negative tests 3
• The test shows 88% positivity rate in patients with confirmed hip joint pathology on arthroscopy 4
• The sensitivity for detecting pathological cam-type FAI (alpha angle ≥78°) is 84.8% with a negative predictive value of 86% 3

Anatomical Basis of the Test

Capsular Ligament Involvement

• The FABER position creates significant strain in the lateral band of the iliofemoral ligament (14.6% strain), with the greatest strain occurring in the distal portion of the lateral border (51.1% strain) 5
• Limited range of motion during the FABER test may be caused by excessive tension in the lateral band of the iliofemoral ligament, not just intra-articular pathology 5

Clinical Interpretation Algorithm

When FABER Test is Positive

• Proceed with anteroposterior pelvis and lateral femoral head-neck radiographs as initial imaging 2, 6
• If three-dimensional assessment is needed or to evaluate intra-articular structures (labrum, cartilage, ligamentum teres), obtain MRI or MR arthrography 2, 6
• Consider the FABER distance test: a difference of ≥4 cm between hips suggests cam-type FAI 3
• Always combine imaging findings with clinical signs and symptoms—never diagnose based on imaging alone 1, 2

When FABER Test is Negative

• Consider alternative diagnoses including lumbar spine pathology, sacroiliac joint dysfunction, or other competing musculoskeletal conditions 2
• Exclude serious pathology including tumors, infections, stress fractures, and slipped capital femoral epiphysis 2
• If hip-related pain persists despite negative test, imaging should still be combined with clinical signs and symptoms rather than relying on clinical tests alone 2

Measurement Reliability

Standardized Measurement Approach

• FABER height measurements demonstrate good inter-rater reliability (ICC 0.67-0.68) and good to excellent intra-rater reliability (ICC 0.76-0.86) 7
• The minimal detectable change for FABER height is 3.7 cm 7
• Use of digital inclinometry may increase reliability (ICC 0.91) compared to ruler measurements 7
• Normal FABER height averages 12.4 ± 2.8 cm in healthy individuals 7

Critical Clinical Pitfalls

Diagnostic Limitations

• Imaging findings must always be combined with patient symptoms and clinical signs—incidental labral tears and other findings are common in asymptomatic individuals 1, 2
• A positive FABER test has limited diagnostic specificity and cannot differentiate between various hip pathologies 2
• Plain radiographs are often normal even in the presence of significant intra-articular pathology 4
• MR arthrography, while highly specific (100%), has lower sensitivity with relatively high false-negative rates 4

Coexisting Conditions

• Many hip-related pain conditions, especially labral and chondral pathology, coexist with FAI syndrome 2
• The test may be positive in sacroiliac joint pathology or other non-hip conditions 2
• Hip arthroscopy remains the definitive diagnostic procedure when clinical suspicion is high despite negative imaging 4