What is the initial approach for a patient presenting with posterior thigh symptoms related to Faber's (Flexion, Abduction, and External Rotation) test?

Initial Approach for Posterior Thigh Symptoms Related to FABER Test

For patients presenting with posterior thigh symptoms related to the FABER (Flexion, Abduction, and External Rotation) test, the initial approach should include radiographic evaluation with AP pelvis and lateral femoral head-neck radiographs, followed by MRI/MRA if three-dimensional assessment is needed to evaluate for hip-related pathology. 1

Diagnostic Assessment

Clinical Evaluation

• A positive FABER test is a key clinical finding in patients with hip-related pain, with high sensitivity but limited specificity 2
• The FABER test should be combined with other clinical tests, such as the FADIR (Flexion, Adduction, Internal Rotation) test, to improve diagnostic accuracy 1, 2
• A negative FADIR test helps rule out hip disease in young and middle-aged adults presenting with hip-related pain 1
• Assessment of hip range of motion, particularly internal rotation in neutral position, can help identify patients with hip pathology 2
• Pain localization to the posterior thigh during FABER testing may indicate extra-articular ischiofemoral impingement 3

Imaging Studies

• Plain radiographs (AP pelvis and lateral femoral head-neck views) are recommended as the initial imaging modality for patients with suspected hip-related pain 1
• MRI or MRA is recommended when three-dimensional morphological assessment is indicated or to evaluate intra-articular structures such as the labrum, cartilage, and ligamentum teres 1
• Diagnostic utility of imaging for hip disease is limited; imaging findings should always be combined with the patient's symptoms and clinical signs 1
• 3D CT-based impingement simulation may be beneficial in cases of suspected posterior extra-articular ischiofemoral impingement to identify the specific impingement location 3

Differential Diagnosis

Hip-Related Pathologies

• Hip-related pain may be categorized into three main conditions after imaging 1:

  1. Femoroacetabular impingement (FAI) syndrome
  2. Acetabular dysplasia and/or hip instability
  3. Other conditions causing hip-related pain (including soft tissue conditions without specific bony morphology)

• Posterior extra-articular ischiofemoral impingement can occur between the ischium and the lesser or greater trochanter in patients with increased femoral version 3

Non-Hip Pathologies to Consider

• Both non-musculoskeletal and serious hip pathological conditions (e.g., tumors, infections, stress fractures) should be excluded 1
• Competing musculoskeletal conditions, such as lumbar spine pathology, should be considered in the differential diagnosis 1
• Peripheral arterial disease should be considered, especially in patients with exertional symptoms or claudication 4, 5

Management Approach

Initial Management

• For confirmed hip-related pathology, the initial approach should be guided by the specific diagnosis 1
• For posterior extra-articular ischiofemoral impingement, consider both the posterior impingement test and a modified FABER test during clinical examination 3
• If vascular etiology is suspected, implement cardiovascular risk reduction strategies and consider antiplatelet therapy if ABI <0.90 4, 5

Advanced Management

• For persistent symptoms despite conservative management, consider:
  • Intra-articular diagnostic injection to confirm intra-articular pathology 6
  • 3D CT for surgical planning in cases of femoral version abnormalities 3
  • Surgical options may include femoral derotation osteotomy, hip arthroscopy, or resection of the lesser trochanter in cases of ischiofemoral impingement 3

Important Considerations and Pitfalls

• Hip pathology, particularly labral pathology, may be more common than previously recognized and should be considered in patients with chronic groin and low back pain 6
• Plain radiographs may appear normal despite significant intra-articular pathology 6
• MRI arthrography may have high specificity but lower sensitivity for hip pathology, with a relatively high number of false negatives 6
• Combining multiple clinical tests (e.g., FABER, FADIR, and ROM assessment) increases diagnostic accuracy compared to using individual tests 2
• The FABER test has shown high specificity and positive predictive value among physical tests for sacroiliac joint dysfunction, suggesting its utility in differentiating hip from sacroiliac pathology 7