What is a Positive FABER Test?
A positive FABER (Flexion, Abduction, External Rotation) test indicates possible hip joint pathology—including acetabular dysplasia, hip instability, labral tears, or femoroacetabular impingement syndrome—but has limited diagnostic specificity and cannot confirm any single condition. 1, 2
Test Interpretation and Diagnostic Limitations
Primary Clinical Utility
- The FABER test is not recommended for ruling in or confirming specific hip pathology due to its low diagnostic precision and magnitude, as shown in the International Hip-related Pain Research Network consensus 1
- A positive test may indicate acetabular dysplasia, hip instability, labral pathology, FAI syndrome, or other intra-articular conditions—it is non-specific 2, 3
- In one study of 25 consecutive hip arthroscopies, 88% (15/17) of patients with confirmed hip pathology had positive FABER tests, though all had pathology regardless of test result 4
Diagnostic Accuracy Characteristics
- The FABER test demonstrates substantial inter-rater reliability (kappa > 0.6) between experienced examiners 5
- Research shows the FABER distance test (comparing side-to-side differences ≥4 cm) has 85% sensitivity and 86% negative predictive value for detecting pathological cam-type FAI (alpha angle ≥78°) 6
- However, the test has low specificity and should not be used to confirm diagnosis 1, 5
Clinical Context and Associated Findings
What a Positive Test Suggests
- Hip joint pathology is present, particularly when combined with restricted and painful hip quadrant movement compared to the contralateral side 4
- In symptomatic patients, a positive FABER distance test correlates with higher alpha angles (average 74° vs 68° in negative tests) 6
- At 5-year follow-up after hip arthroscopy, 25% of patients still had positive FABER tests, and those with positive tests had significantly worse patient-reported outcomes 7
Critical Diagnostic Principle
Imaging findings must always be combined with patient symptoms and clinical signs—diagnosis should never be made based on imaging or clinical tests alone 1, 2, 3
Algorithmic Approach When FABER is Positive
Step 1: Exclude Serious Pathology
- Rule out tumors, infections, stress fractures, slipped capital femoral epiphysis (SCFE), and competing musculoskeletal conditions (especially lumbar spine pathology) 2, 3
Step 2: Initial Imaging
- Obtain anteroposterior (AP) pelvis and lateral femoral head-neck radiographs to assess osseous morphology, dysplasia, and degenerative changes 1, 2, 3
Step 3: Advanced Imaging if Indicated
- For suspected labral tears specifically, MR arthrography is superior to CT arthrography and non-contrast MRI 2, 3
- Advanced imaging (MRI/MRA or CT) should be used when three-dimensional morphological assessment is needed 1
Step 4: Clinical Correlation
- Beware of incidental findings: labral tears, chondral lesions, and ligamentum teres pathology are common on imaging in asymptomatic individuals 2, 3
- Consider diagnostic/therapeutic intra-articular injection to confirm intra-articular pathology as the pain source 2, 3
Common Pitfalls to Avoid
- Do not diagnose based on a positive FABER test alone—it lacks the specificity to confirm any particular hip condition 1, 3
- A positive test occurs in 7.3% of healthy 19-year-old males and 4.8% of healthy females, so it is not uncommon in asymptomatic individuals 8
- Plain radiographs may be normal despite significant intra-articular pathology—negative radiographs do not exclude hip disease 4
- The FABER test should be combined with other clinical findings (especially the FADIR test, which is the recommended screening test) and imaging for comprehensive assessment 1, 2