The “Figure 4 Test,” formally known as the FABER test, is a common orthopedic screening tool used to assess potential sources of pain in the hip and pelvis. FABER is an acronym representing the three movements the hip undergoes: Flexion, Abduction, and External Rotation. This passive movement assessment involves the healthcare provider moving the patient’s limb to stress specific anatomical structures. It helps differentiate between intra-articular hip issues and extra-articular problems, such as sacroiliac joint dysfunction, providing clues about the origin of lower back, buttock, or groin pain.
Executing the Figure 4 Test
The procedure begins with the patient lying flat on their back on an examination table (supine). The clinician stands on the side of the leg being tested and gently flexes the patient’s hip and knee. The foot of the leg being examined is then placed on the opposite knee, resting just above or below the kneecap, creating the distinctive “figure-four” shape.
This positioning places the hip joint into combined flexion, abduction, and external rotation. To prevent compensatory movement, the clinician stabilizes the pelvis. One hand is placed on the anterior superior iliac spine (ASIS) on the side opposite the tested leg.
With the pelvis stabilized, the examiner applies gentle, downward pressure (overpressure) against the medial side of the bent knee, directing the force toward the table. This further stresses the hip and surrounding structures. The clinician observes the patient’s range of motion and notes if the maneuver reproduces the patient’s familiar pain.
Anatomical Targets of the Test
The specific motions of flexion, abduction, and external rotation mechanically provoke both the hip joint and the sacroiliac (SI) joint. Deep flexion and external rotation place significant torque and compression on the femoral-acetabular joint. This stresses the cartilage and the joint capsule, including the posterior capsule.
The abduction motion, combined with downward overpressure, transfers tension across the pelvis to the SI joint. This stress makes the test a useful screen for SI joint dysfunction. The maneuver also stretches several soft tissue structures.
The position maximally stresses the hip flexors, such as the iliopsoas muscle, and the adductor muscles in the inner thigh. Pain can be elicited if there is tightness or irritation in these muscles or their tendons. The FABER maneuver is a broad mechanical provocation designed to identify structures sensitive to this combined position.
Interpreting a Positive Result
A positive result on the FABER test occurs when the maneuver reproduces the patient’s pain or demonstrates a limited range of motion compared to the unaffected side. The location of the pain during the test provides the primary clue for the potential source of the problem.
Pain felt in the anterior hip or groin region is suggestive of pathology within the hip joint itself. This anterior discomfort points toward intra-articular issues such as hip osteoarthritis, a tear in the acetabular labrum, or femoroacetabular impingement. The deep compression of the joint surfaces during the test exacerbates pain from these conditions.
Conversely, if the patient reports pain localized to the posterior side, specifically in the buttock or sacral area, it suggests involvement of the sacroiliac joint. The mechanical stress transferred across the pelvis during the test directly provokes the SI joint, and the reproduction of pain there is a strong indicator of dysfunction in that region.
It is important to remember that the FABER test is a screening tool, not a definitive diagnosis. Although a positive result is significant, particularly for labral tears or hip pathology, further specialized imaging and a cluster of other orthopedic tests are often required to confirm the precise diagnosis.