FABER Test: Understanding, Performance, and Interpretation for Hip OA

What is the FABER Test for OA?

The FABER test, an acronym for Flexion, Abduction, and External Rotation, is a common orthopedic assessment used primarily to evaluate hip joint pathology, particularly in the context of osteoarthritis (OA), as well as sacroiliac joint dysfunction.

Understanding the FABER Test

The FABER test, also known as Patrick's test, is a passive range of motion assessment that places the hip joint in a specific position to stress various structures around the hip and pelvis. It's a foundational component of orthopedic examination for lower limb complaints, providing valuable insights into potential sources of pain or restricted movement. The name itself describes the three key movements the hip undergoes during the test:

• Flexion: Bending the hip.
• Abduction: Moving the leg away from the midline of the body.
• External Rotation: Turning the thigh outward.

This combined position maximally stresses the anterior and lateral aspects of the hip capsule, the iliopsoas muscle, adductor muscles, and the sacroiliac (SI) joint.

The FABER Test and Osteoarthritis

While the FABER test is not exclusively diagnostic for osteoarthritis, it is a highly relevant tool in its assessment, particularly for hip OA.

How it Relates to OA: Osteoarthritis of the hip typically leads to a progressive loss of cartilage, resulting in pain, stiffness, and reduced range of motion. The FABER position, which involves significant hip flexion, abduction, and external rotation, often exacerbates symptoms in individuals with hip OA due to:

• Joint Space Narrowing: Reduced cartilage can cause bone-on-bone contact in certain positions, leading to pain.
• Capsular Tightness: Chronic inflammation and degeneration can lead to thickening and tightening of the hip joint capsule, restricting movement.
• Osteophyte Formation: Bone spurs can impinge on surrounding soft tissues or other bones during movement.

Common OA Locations Assessed: The FABER test primarily assesses the hip joint. However, it's crucial to understand that pain elicited during the test can also indicate issues with the sacroiliac (SI) joint, which is a common site for referred pain or can be a primary source of pain mimicking hip problems. Differentiating between hip and SI joint pathology is a key aspect of interpreting the FABER test.

How the FABER Test is Performed

The FABER test is a simple, non-invasive procedure typically performed by a healthcare professional.

Patient Positioning:

• The patient lies supine (on their back) on an examination table or firm surface.
• The legs are extended straight.

Execution Steps:

1. Flexion and External Rotation: The examiner passively flexes the patient's hip and externally rotates it so that the ankle of the tested leg rests on the opposite thigh, just above the knee (forming a "figure-4" position).
2. Stabilization: The examiner places one hand on the anterior superior iliac spine (ASIS) of the opposite hip to stabilize the pelvis and prevent it from rotating.
3. Abduction Pressure: With the other hand, the examiner gently but firmly presses down on the medial aspect of the flexed knee, guiding the leg towards the examination table. The goal is to allow the hip to abduct as much as possible without forcing the movement.
4. Observation: The examiner observes the range of motion and monitors the patient's reaction for pain or discomfort.

Key Observations:

• Pain Location: Note where the patient reports pain (e.g., anterior hip, posterior hip, groin, low back, SI joint).
• Pain Quality: Describe the type of pain (e.g., sharp, dull ache, deep, superficial).
• Range of Motion: Observe the degree of abduction achieved. Is it limited compared to the other side or to expected norms?
• End-Feel: Assess the quality of resistance at the end of the range of motion (e.g., firm, soft, empty).

Interpreting FABER Test Results for OA

Interpretation of the FABER test requires clinical judgment and consideration of other findings.

Positive Test Indicators:

• Reproduction of Pain: The most significant indicator is the reproduction of the patient's chief complaint of pain, especially in the groin or anterior hip region, which often points towards hip joint pathology, including OA.
• Limited Range of Motion: If the tested knee remains significantly elevated above the opposite leg or cannot be lowered to the same degree as the unaffected side, it suggests restricted hip abduction and/or external rotation, often due to capsular tightness or intra-articular pathology like OA.
• Asymmetry: A notable difference in pain or range of motion between the affected and unaffected sides is a strong indicator of pathology.

Clinical Significance: A positive FABER test, particularly with pain localized to the hip joint, strongly suggests an issue within the hip. In the context of suspected OA, it supports the diagnosis, especially when combined with other clinical signs and imaging findings.

Differential Diagnosis Considerations: It's crucial to differentiate between hip and SI joint pain:

• Hip Joint Pain: Typically felt in the groin, anterior hip, or sometimes radiating to the knee.
• Sacroiliac (SI) Joint Pain: Often felt in the buttock, posterior hip, or lower back. If pain is elicited only when pressure is applied to the ASIS (stabilizing the pelvis) and the pain is posterior, it leans more towards SI joint dysfunction. If pain is elicited without stabilization, it could be a hip issue.

Clinical Utility and Limitations

Like any orthopedic test, the FABER test has its strengths and limitations.

Strengths:

• Ease of Use: Simple to perform in a clinical setting without specialized equipment.
• Versatility: Can help identify a range of hip and SI joint pathologies.
• Functional Relevance: The position mimics common movements that can be painful for individuals with hip OA.
• Screening Tool: Useful as an initial screening tool to narrow down potential causes of hip or groin pain.

Limitations:

• Non-Specific: A positive test does not definitively diagnose OA. It indicates pathology in the region, but not the specific cause. Pain can also arise from iliopsoas tendinitis, adductor strains, labral tears, or SI joint dysfunction.
• Subjectivity: Interpretation relies on patient feedback and examiner observation, which can be subjective.
• Not a Standalone Diagnostic: The FABER test should always be part of a comprehensive orthopedic examination, including patient history, other special tests, and potentially imaging (X-rays, MRI) for a definitive diagnosis of OA.
• Pain Tolerance: Patient pain tolerance can influence the perceived range of motion and pain response.

Beyond the FABER Test

While the FABER test is a valuable component of assessing hip health, especially in the context of potential osteoarthritis, it is never used in isolation for diagnosis. A thorough clinical evaluation for hip OA typically includes:

• Detailed Patient History: Understanding the onset, duration, nature, and aggravating/alleviating factors of pain.
• Other Physical Examination Tests: Assessing gait, palpation, muscle strength, and other specific hip tests (e.g., FADIR test for impingement, Trendelenburg test for gluteal weakness).
• Imaging Studies: X-rays are the gold standard for diagnosing hip OA, showing joint space narrowing, osteophytes, and subchondral sclerosis. MRI may be used to assess soft tissues or early cartilage changes.
• Functional Assessment: Evaluating how the hip pain impacts daily activities, such as walking, climbing stairs, or putting on shoes.

Conclusion

The FABER test is an important clinical assessment tool for evaluating the hip and sacroiliac joints. When considering osteoarthritis, particularly of the hip, a positive FABER test indicating pain in the groin or restricted range of motion provides strong supportive evidence for hip pathology. However, it is crucial to remember that it is a non-specific test and must be interpreted within the broader context of a comprehensive clinical examination, patient history, and often, diagnostic imaging. For fitness professionals, understanding the FABER test enhances your ability to recognize potential issues requiring medical referral, ensuring your clients receive appropriate and safe care.