Figure 4 Test (FABER Test): Purpose, Performance, and Interpretation for Hip and SI Joint

What is the Figure 4 Test for Hip?

The Figure 4 Test, also widely known by its acronym FABER (Flexion, Abduction, External Rotation) Test, is a common orthopedic assessment used to evaluate hip joint mobility, assess for sacroiliac joint dysfunction, and identify potential hip pathologies such as impingement or tightness in the hip adductors and external rotators.

Understanding the Figure 4 Test (FABER Test)

The Figure 4 Test derives its name from the patient's leg position during the assessment, which resembles the numeral "4." Its more formal name, FABER, succinctly describes the three movements the hip joint undergoes during the test: Flexion, Abduction, and External Rotation.

This test serves as a valuable screening tool for clinicians, physical therapists, and fitness professionals to gain insight into the function and potential limitations of the hip and surrounding structures. It is not a standalone diagnostic test but provides crucial information when integrated into a comprehensive examination.

Key Anatomy Involved

To fully appreciate the Figure 4 Test, it's essential to understand the primary anatomical structures being assessed:

• Hip Joint: A ball-and-socket synovial joint formed by the head of the femur (thigh bone) and the acetabulum of the pelvis. Its design allows for a wide range of motion, including flexion, extension, abduction, adduction, and internal/external rotation.
• Sacroiliac (SI) Joint: The strong, weight-bearing joint connecting the sacrum (triangular bone at the base of the spine) to the ilium (largest part of the hip bone). Dysfunction here can often mimic hip pain.
• Muscles:
  • Hip Adductors: Muscles on the inner thigh (e.g., adductor magnus, longus, brevis, pectineus, gracilis) that bring the leg towards the midline. Tightness can restrict abduction.
  • Hip External Rotators: A group of deep muscles (e.g., piriformis, gemelli, obturators, quadratus femoris) that rotate the thigh outwards.
  • Iliopsoas: A powerful hip flexor located at the front of the hip. Tightness can contribute to anterior hip pain.
• Joint Capsule and Ligaments: The fibrous capsule surrounding the hip joint and its strong reinforcing ligaments (iliofemoral, pubofemoral, ischiofemoral) play a critical role in joint stability and can become tight, restricting motion.

How to Perform the Figure 4 Test

The Figure 4 Test is typically performed with the individual lying on their back (supine position).

1. Patient Positioning: The individual lies supine on a firm surface (e.g., examination table, floor).
2. Test Leg Preparation:
   • The examiner passively flexes the hip and knee of the leg being tested.
   • The ankle of the tested leg is then placed on the opposite thigh, just above the knee, creating the "figure 4" shape. This position places the hip in flexion, abduction, and external rotation.
3. Stabilization: The examiner places one hand on the anterior superior iliac spine (ASIS) of the opposite (non-tested) hip to stabilize the pelvis and prevent it from rotating during the test.
4. Application of Overpressure: With the other hand, the examiner gently applies downward pressure to the medial aspect (inside) of the tested knee, directing it towards the surface. The goal is to see how close the knee can get to the surface without pain or excessive pelvic movement.
5. Observation and Assessment: The examiner observes the range of motion, notes any reproduction of pain, and assesses the quality of the movement. The test is then repeated on the other side for comparison.

Interpreting the Results

The interpretation of the Figure 4 Test depends on the presence and location of pain, as well as the observed range of motion.

• Negative Test:

  • The tested knee drops to or very close to the surface (indicating full hip abduction and external rotation) without any pain. This suggests good hip joint mobility and no significant issues with the hip or SI joint.

• Positive Test: A positive test can manifest in several ways:

  • Restricted Range of Motion (ROM): If the tested knee remains significantly elevated from the surface, it indicates tightness in the structures limiting hip abduction and external rotation. This could be due to:

    • Tightness in the hip adductor muscles.
    • Tightness in the hip external rotator muscles (paradoxically, as the test puts them on stretch).
    • Stiffness or capsular restrictions within the hip joint itself.

  • Pain in the Hip/Groin Region: If pain is reproduced deep within the hip joint or in the groin area (anterior hip) as overpressure is applied, it often suggests:

    • Hip Impingement (FAI): Particularly femoroacetabular impingement, where abnormal bone shapes cause structures to pinch during movement.
    • Hip Osteoarthritis: Degenerative changes in the joint.
    • Labral Tear: Damage to the cartilage rim of the hip socket.
    • Iliopsoas Tendinopathy/Tightness: Pain from the hip flexor tendon.

  • Pain in the Sacroiliac (SI) Joint Region: If pain is felt in the posterior hip, buttock, or lower back (over the SI joint), especially if the pain is reproduced with the overpressure and relieved when the pressure is removed, it strongly suggests:

    • Sacroiliac Joint Dysfunction: Instability, inflammation, or hypomobility of the SI joint.

Clinical Significance and Applications

The Figure 4 Test is a cornerstone in orthopedic and physical therapy assessments for several reasons:

• Differentiating Pain Sources: It helps clinicians distinguish between pain originating from the hip joint itself versus pain emanating from the sacroiliac joint, which can often be confused due to their proximity.
• Assessing Mobility Deficits: It quickly identifies limitations in hip external rotation and abduction, guiding targeted interventions such as stretching, manual therapy, or mobility exercises.
• Screening for Pathology: While not diagnostic on its own, a positive FABER test with specific pain patterns can alert the examiner to potential underlying conditions like hip impingement or arthritis, prompting further investigation (e.g., imaging).
• Guiding Rehabilitation: Understanding the specific limitations or pain generators helps fitness professionals and therapists design more effective exercise programs and rehabilitation strategies.

Important Considerations and Limitations

While valuable, the Figure 4 Test has its limitations:

• Subjectivity: The interpretation relies on the patient's pain report and the examiner's subjective assessment of range of motion.
• Specificity: A positive test is not specific to one single pathology. For example, anterior hip pain could be impingement or iliopsoas tightness. Further tests are always needed to confirm a diagnosis.
• Patient Tolerance: The test can be uncomfortable for individuals with significant hip pain or stiffness. Overpressure should always be applied gently and ceased if severe pain occurs.
• Contraindications: It should be avoided or performed with extreme caution in individuals with acute hip injuries, recent hip surgery, or severe hip joint degeneration.

Conclusion

The Figure 4 Test, or FABER Test, is an essential tool in the assessment of hip and pelvic function. By systematically evaluating hip flexion, abduction, and external rotation, it provides critical insights into joint mobility, muscle tightness, and potential pathologies of both the hip and sacroiliac joints. For fitness enthusiasts and professionals alike, understanding this test enhances the ability to identify potential issues, guide appropriate training modifications, and recognize when to seek further medical evaluation for comprehensive diagnosis and management of hip-related concerns.