The term “Figure 4 Test” is a common lay description for an orthopedic maneuver used to assess the lower body. The test is most widely recognized for evaluating issues in the hip joint and the sacroiliac (SI) joint, which connects the hip bones to the spine. While patients often search for its use in connection with knee pain, the test is not a primary diagnostic tool for the knee itself. Understanding this distinction is necessary for properly interpreting the results of the maneuver.
Identifying the Specific Orthopedic Test
The formal name for the “Figure 4 Test” is the Flexion, Abduction, and External Rotation (FABER) test, sometimes also referred to as Patrick’s Test. This acronym precisely describes the three movements the hip is put through during the assessment. The FABER test is designed to put stress on the hip joint capsule, the surrounding hip flexor muscles, and the SI joint. It is a tool for evaluating pathology within the hip or pelvis, not the knee.
The connection to knee pain is often due to referred pain, which arises from shared nerve pathways between the hip and knee. Pain originating from a hip problem, such as osteoarthritis or a labral tear, can be perceived in the anterior part of the thigh and knee. This occurs because the obturator and femoral nerves innervate both areas, making the location of the actual problem misleading. Clinicians often perform the FABER test on patients with knee pain to rule out a hip or SI joint problem as the true source of discomfort.
Test Procedure and Execution
The execution of the FABER test is standardized, beginning with the patient lying flat on their back. The leg being tested is brought into the characteristic “figure 4” position by flexing the hip and knee. The ankle of the tested leg is placed just above the kneecap of the opposite, straight leg. This placement guides the hip into flexion, external rotation, and abduction.
The examiner places one hand on the patient’s pelvis, specifically on the anterior superior iliac spine (ASIS), to stabilize the pelvis and prevent it from rotating. The other hand is placed on the inside of the bent knee. The examiner then gently applies progressive downward pressure to the flexed knee, pushing it toward the examination table. This overpressure further stresses the hip joint and the sacroiliac joint.
A positive result is determined by the patient’s reaction, typically the reproduction of their familiar pain. It can also be indicated by a restriction in the range of motion compared to the opposite, non-tested side.
Interpreting Results and Pain Location
The interpretation of the FABER test hinges on the location where the patient reports feeling their pain or restriction. A positive test is indicated by the reproduction of discomfort or a noticeable limitation in the hip’s ability to externally rotate and abduct. If the pain is localized to the groin or the anterior aspect of the hip, this strongly suggests a problem within the hip joint itself. Examples include osteoarthritis, femoroacetabular impingement, or a labral tear.
If the pain is felt in the posterior region or over the sacroiliac joint, the test is considered positive for SI joint dysfunction. When a patient reports pain specifically in the knee during this maneuver, it usually indicates the problem is referred from the hip or the SI joint. It may also be a secondary strain caused by an altered gait pattern. A positive FABER test shifts the focus of the diagnosis away from primary knee pathology toward a hip or pelvic origin.