Negative FABER and FADIR Tests: Clinical Significance
A negative FADIR test helps rule out hip disease in young and middle-aged active adults with hip-related pain, while a negative FABER test combined with absence of groin pain effectively excludes femoroacetabular impingement (FAI) syndrome and labral pathology. 1
Primary Clinical Utility: Rule-Out Function
Negative tests are most valuable for excluding hip pathology rather than confirming it. The International Hip-related Pain Research Network consensus strongly recommends (median score 9/9) that a negative FADIR test helps rule out hip disease in young and middle-aged active adults presenting with hip-related pain. 1
Specific Rule-Out Capabilities
- FADIR test: When negative, effectively rules out hip-related pain including FAI syndrome, acetabular dysplasia/instability, and labral/chondral/ligamentum teres conditions 1, 2
- FABER test combined with pain location: The combination of a negative FABER test AND absence of groin as the main pain location achieves 97% sensitivity for ruling out symptomatic FAI and labral pathology 3
- Alternative high-sensitivity combination: A negative anterior impingement test (AIT) combined with a negative FABER test also effectively rules out FAI syndrome and labral pathology 3
Diagnostic Accuracy Characteristics
The FADIR test demonstrates high sensitivity (80%) but low specificity (25-26%), making it ideal for ruling out disease when negative but poor for confirming disease when positive. 4 Similarly, the FABER test shows high sensitivity (72-91%) with modest specificity. 4, 3
Important Limitation
These tests have very limited ability to confirm hip pathology when positive. The low specificity means positive tests generate many false positives and should not be used to rule in disease. 1, 4 The consensus guidelines explicitly state these tests have "very limited ability to confirm FAI syndrome by increasing post-test probability." 1
Clinical Decision Algorithm When Tests Are Negative
When both FABER and FADIR tests are negative:
- Consider alternative diagnoses: Evaluate for lumbar spine pathology, sacroiliac joint dysfunction, or other competing musculoskeletal conditions 1, 5
- Exclude serious pathology: Rule out non-musculoskeletal conditions including tumors, infections, stress fractures, and slipped capital femoral epiphysis (SCFE) 1
- Reassess symptom pattern: If hip-related pain persists despite negative tests, imaging should still be combined with clinical signs and symptoms rather than relying on clinical tests alone 1
Reliability Considerations
Inter-rater reliability is substantial for both tests (kappa >0.6), meaning different experienced clinicians will obtain consistent results. 4 The FABER test demonstrates good to excellent intra-rater reliability (ICC 0.76-0.86), with the minimal detectable change being 3.7 cm when measured with a ruler. 6
Common Pitfall to Avoid
Do not use negative tests to completely exclude hip pathology in isolation. The consensus guidelines emphasize that imaging findings must always be combined with patient symptoms and clinical signs, never used in isolation. 1 Even with negative clinical tests, if clinical suspicion remains high based on history and symptom pattern, proceed with appropriate imaging (AP pelvis and lateral femoral head-neck radiographs initially). 1, 7, 2
Long-Term Prognostic Value
Research demonstrates that even after successful hip arthroscopy for FAI syndrome, 36% of patients have a positive FADIR test and 25% have a positive FABER test at 5-year follow-up, indicating these tests may remain positive despite symptom improvement. 8 This reinforces that negative tests are more clinically meaningful than positive tests in the diagnostic workup.