FABER Test: Other Names, Purpose, Performance, and Interpretation

What is another name for the Faber test?

The FABER test, a cornerstone orthopedic assessment, is widely recognized by several names, most commonly Patrick's Test or, less formally, the Figure-4 Test, due to the distinctive position the leg assumes during its execution.

Understanding the FABER Test: An Overview

The FABER test is a clinical orthopedic maneuver used by healthcare professionals, including physical therapists, chiropractors, and orthopedic surgeons, to assess the hip and sacroiliac (SI) joints. The acronym FABER stands for Flexion, ABduction, and External Rotation—the three primary movements performed on the hip during the test. While its formal name derives from these movements, its widespread alternative, Patrick's Test, honors the physician who first described it, Dr. Hugh Patrick. The informal "Figure-4 Test" aptly describes the visual shape of the tested leg. This test is invaluable for identifying potential pathologies within the hip joint itself or dysfunction originating from the sacroiliac joint.

Anatomy and Biomechanics Behind the Test

To understand the FABER test, it's crucial to grasp the anatomy and biomechanics involved:

• Hip Joint: A ball-and-socket joint formed by the head of the femur fitting into the acetabulum of the pelvis. It allows for a wide range of motion, including flexion, extension, abduction, adduction, and internal/external rotation. The FABER position significantly stresses the anterior and superior aspects of the hip capsule and associated structures.
• Sacroiliac (SI) Joint: Located where the sacrum (the triangular bone at the base of the spine) meets the ilium (the largest part of the hip bone). This joint has limited movement but is a common source of lower back and buttock pain. The FABER position, especially with applied overpressure, can induce rotational stress on the SI joint.
• Muscles and Ligaments: The test stretches various muscles and ligaments around the hip and pelvis. Key muscles include the hip flexors (e.g., iliopsoas), adductors (e.g., adductor longus, magnus, brevis), and external rotators (e.g., piriformis, obturator internus). Ligaments such as the iliofemoral, pubofemoral, and ischiofemoral ligaments of the hip capsule, as well as the strong SI joint ligaments, are also put under tension.

The combined movements of flexion, abduction, and external rotation place the hip in a position that compresses the anterior-superior aspect of the joint and simultaneously stretches the posterior capsule and surrounding soft tissues. This mechanical stress can elicit pain if there is pathology within the hip joint or the SI joint.

Clinical Purpose and Indications

The FABER test serves several important diagnostic purposes:

• Assessing Hip Joint Pathology: It is a primary screening tool for conditions affecting the hip joint itself, such as:
  • Osteoarthritis (OA) of the hip
  • Femoroacetabular Impingement (FAI)
  • Labral tears
  • Capsulitis or capsular tightness
  • Avascular necrosis of the femoral head
• Identifying Sacroiliac (SI) Joint Dysfunction: Pain localized to the posterior aspect of the hip or SI joint during the test can indicate SI joint inflammation, sprain, or hypomobility.
• Detecting Muscle or Capsular Tightness: A limitation in the range of motion without pain may suggest tightness in the hip adductors, iliopsoas, or restrictions within the hip joint capsule.
• Differentiating Pain Sources: By observing the location of the patient's pain response, clinicians can often differentiate whether the pain is primarily originating from the hip joint (anterior/groin pain) or the SI joint (posterior/buttock pain).

Performing the FABER Test (Patrick's Test)

The FABER test is a simple yet effective maneuver when performed correctly:

• Patient Positioning: The patient lies supine (on their back) on an examination table.
• Examiner Action: The examiner stands beside the patient, typically on the side of the leg being tested.
• The "Figure-4" Position:
  • The examiner passively flexes the patient's hip and knee.
  • The ankle of the leg being tested is then placed on the opposite knee, creating a "figure-4" shape with the legs. This achieves the flexion and external rotation components.
  • The examiner then gently abducts the tested hip by allowing the knee to drop towards the examination table.
• Overpressure Application: Once the knee has dropped as far as comfortable or possible, the examiner may apply gentle, controlled overpressure to the medial aspect of the knee (pushing it further towards the table) while stabilizing the opposite anterior superior iliac spine (ASIS) to prevent pelvic rotation.
• Bilateral Comparison: The test should always be performed bilaterally (on both legs) to compare the range of motion and pain response between the symptomatic and asymptomatic sides.

Interpreting the Results

Interpreting the FABER test involves observing the patient's range of motion and the location of any elicited pain:

• Positive Test for Hip Joint Pathology: If the patient experiences pain in the anterior hip or groin region during the maneuver, especially with overpressure, it suggests a problem within the hip joint itself. This could indicate osteoarthritis, femoroacetabular impingement, or a labral tear.
• Positive Test for Sacroiliac (SI) Joint Dysfunction: If the patient reports pain in the posterior hip, buttock, or directly over the sacroiliac joint, it indicates potential SI joint pathology.
• Limited Range of Motion (without pain): If the tested knee remains significantly elevated from the table (i.e., unable to drop fully) without eliciting pain, it may suggest tightness in the hip adductor muscles, iliopsoas tightness, or a restriction within the hip joint capsule.
• Comparison to Asymptomatic Side: A significant difference in range of motion or pain provocation compared to the unaffected side is crucial for clinical decision-making.

Limitations and Clinical Considerations

While the FABER test is a valuable screening tool, it has limitations:

• Lack of Specificity: A positive FABER test is not highly specific for a single diagnosis. Both hip and SI joint issues can result in a positive test, and the exact pain location is key for differentiation. It often requires correlation with other orthopedic tests and diagnostic imaging.
• False Positives/Negatives: It is possible for individuals with hip or SI joint issues to have a negative FABER test, and vice versa.
• Patient Comfort: The test can be uncomfortable for patients with significant pain or limited mobility. Examiners must proceed with caution and respect the patient's pain tolerance.
• Comprehensive Assessment: The FABER test should always be part of a comprehensive orthopedic examination, including a thorough patient history, other special tests, neurological examination, and functional movement assessment.

Conclusion

The FABER test, also known as Patrick's Test or the Figure-4 Test, is an indispensable tool in musculoskeletal assessment. By strategically positioning the hip in flexion, abduction, and external rotation, it effectively stresses both the hip and sacroiliac joints, providing valuable insights into potential pathologies. While its interpretation requires careful consideration of pain location and comparison to the contralateral side, when used as part of a broader clinical evaluation, the FABER test significantly aids in diagnosing and guiding treatment for various hip and pelvic girdle dysfunctions. For individuals experiencing hip or lower back pain, a professional evaluation by a qualified healthcare provider is always recommended.