Figure 4 Test: Understanding its Use for Hip, SI, and Referred Knee Pain

What is the Figure 4 Test for Knee Pain?

The Figure 4 Test, also known as the FABER (Flexion, ABduction, External Rotation) test or Patrick's Test, is primarily an orthopedic assessment used to evaluate the hip joint and sacroiliac (SI) joint, not the knee directly. However, because hip and SI joint dysfunction can refer pain to the knee, this test is crucial for differentiating the source of knee pain.

Understanding the Figure 4 Test

The Figure 4 Test is a valuable clinical tool employed by healthcare professionals, including physical therapists, chiropractors, and orthopedic specialists, to assess the mobility and potential pathology of the hip and sacroiliac joints. While its name might suggest a direct link to knee pain, its primary utility lies in identifying issues in the adjacent joints that can manifest as discomfort or pain in the knee region. This phenomenon, known as referred pain, makes a thorough assessment of the hip and SI joint essential when evaluating knee pain, especially when no clear knee injury is present.

Key Applications:

• Hip Joint Pathology: It can help detect conditions like hip osteoarthritis, femoroacetabular impingement (FAI), labral tears, or hip capsular tightness.
• Sacroiliac Joint Dysfunction: The test can elicit pain originating from the SI joint, which is a common source of referred pain to the buttock, groin, and sometimes the posterior or lateral knee.
• Differential Diagnosis: By performing this test, clinicians can begin to differentiate between pain originating directly from the knee versus pain referred from the hip or SI joint, guiding more accurate treatment strategies.

How to Perform the Figure 4 Test

The Figure 4 Test is typically performed with the individual lying on their back. Here's a step-by-step breakdown:

• Patient Position: The individual lies supine (on their back) on an examination table or firm surface.
• Starting Position: The leg being tested is placed in a "figure 4" position. This involves:
  1. Flexing the hip and knee of one leg.
  2. Placing the ankle of the flexed leg onto the opposite knee or thigh. This creates a shape resembling the number "4."
• Stabilization: The examiner places one hand on the anterior superior iliac spine (ASIS) of the opposite, non-tested side to stabilize the pelvis.
• Application of Pressure: With the other hand, the examiner gently applies downward pressure to the medial aspect of the flexed knee, moving it towards the examination table.
• Observation: The examiner observes the range of motion, symmetry with the opposite side, and, critically, the presence and location of any pain elicited during the maneuver.

Interpreting the Results

The interpretation of the Figure 4 Test depends on where the patient experiences pain or if there's a limitation in range of motion.

• Pain in the Inguinal (Groin) Area or Anterior Hip: This suggests a positive test for hip joint pathology. It could indicate issues within the hip joint itself, such as osteoarthritis, labral tears, or capsular tightness.
• Pain in the Sacroiliac (SI) Joint Area or Buttock: This indicates a positive test for sacroiliac joint dysfunction. The SI joint is located where the sacrum meets the ilium in the lower back/buttock region.
• Limited Range of Motion: If the flexed knee does not drop easily towards the examination table, it suggests tightness in the hip adductor muscles, iliopsoas, or hip joint capsule.
• Pain in the Knee (Less Common for Direct Origin): While the test primarily targets the hip and SI, if pain is elicited in the knee, it strongly suggests that the knee pain might be referred from the hip or SI joint. It prompts further investigation into these proximal joints as the source of the knee discomfort. It's crucial to differentiate this from direct knee pathology.

What the Figure 4 Test Does NOT Tell You

It is important to understand the limitations of the Figure 4 Test:

• Not a Direct Knee Diagnostic: This test does not directly diagnose specific knee conditions such as meniscal tears, ligamentous injuries (e.g., ACL, PCL), or patellofemoral pain syndrome.
• Screening Tool, Not Definitive Diagnosis: While highly indicative, a positive Figure 4 test is a screening tool, not a definitive diagnosis. Further orthopedic tests, imaging (like X-rays or MRI), and a comprehensive clinical history are typically required to confirm the exact cause of pain.
• Does Not Isolate Specific Hip Pathology: While it can point to hip joint involvement, it doesn't specify if the issue is osteoarthritis, impingement, or a labral tear without additional assessments.

When to Seek Professional Advice

If you are experiencing persistent knee pain, or if you attempt a modified version of this test (under guidance) and experience pain in your hip, SI joint, or knee, it is crucial to consult a healthcare professional. A physician, physical therapist, or sports medicine specialist can perform a comprehensive evaluation, including a battery of specific orthopedic tests, to accurately diagnose the source of your pain and recommend an appropriate treatment plan. Self-diagnosis based solely on the Figure 4 Test is not recommended.