The Flexion, Abduction, External Rotation (FABER) test, also known as the Patrick test, is an orthopedic screening maneuver used by clinicians to assess the source of pain in the lower back, buttock, or groin region. This procedure helps differentiate between issues originating in the hip joint and those stemming from the surrounding pelvic structures. A positive result does not provide a specific diagnosis but serves as a strong indicator, guiding the healthcare provider to focus their subsequent evaluation on either the hip joint or the sacroiliac region. The test is valued for its ability to quickly narrow down the potential anatomical cause of a patient’s discomfort.
How the FABER Test Works
The procedure begins with the patient lying flat on their back (supine). The examiner places the patient’s leg into the “figure-four” position, where the ankle of the tested leg rests just above the knee of the opposite leg. This position achieves flexion, abduction, and external rotation of the hip.
The clinician stabilizes the pelvis with one hand, typically by holding the opposite hip bone, to prevent the patient from compensating for limited motion. With the other hand, the examiner applies gentle, controlled downward pressure to the inside of the bent knee, guiding it toward the examination table. This movement passively stresses the hip joint capsule and the ligaments surrounding the pelvis. A “positive” result occurs if the patient experiences a reproduction of their familiar pain or if the hip exhibits a notably limited range of motion compared to the unaffected side.
Interpreting Pain Locations
The interpretation of a positive FABER test depends on the anatomical location where the patient feels the pain during the maneuver. The force applied during the test targets both the hip socket and the sacroiliac joint, and the site of pain determines which structure is likely at fault.
Anterior/Groin Pain
If the patient reports pain felt deeply in the anterior hip or groin area, it strongly suggests a problem within the hip joint itself, known as intra-articular pathology. The figure-four position maximally stresses the hip joint capsule and the cartilage structures inside the socket. Conditions often associated with anterior pain during the FABER test include osteoarthritis of the hip, which involves cartilage degradation, or a labral tear, which is damage to the ring of cartilage lining the hip socket. Femoroacetabular impingement (FAI), a condition where abnormal bone shapes rub against one another, is also a common cause of groin pain provoked by this specific movement.
Posterior/Buttock Pain
Conversely, if the patient reports pain localized to the posterior buttock or over the sacrum, it points toward dysfunction of the sacroiliac joint (SIJ). The SIJ connects the sacrum, the triangular bone at the base of the spine, to the pelvis. The downward pressure on the knee during the FABER test creates a rotational force on the pelvis, which stresses the SI joint and its strong supporting ligaments. Reproduction of posterior pain suggests that the SIJ is the source of the patient’s symptoms, a condition sometimes referred to as sacroiliitis.
Follow-up and Confirmatory Diagnosis
Because the FABER test has good sensitivity but low specificity, a positive result necessitates further investigation. The test is considered a single piece of evidence that must be integrated with a detailed patient history and the results of other orthopedic tests. Clinicians often use the FABER test in combination with a “cluster” of other provocation maneuvers, which collectively increase the diagnostic accuracy for SI joint involvement.
The next steps for diagnosis frequently involve advanced imaging to visualize the anatomical structures implicated by the pain location. If anterior hip pain was provoked, imaging like an X-ray can assess for bony changes consistent with osteoarthritis, while a Magnetic Resonance Arthrography (MRA) can provide detailed images of soft tissues like the labrum. For suspected sacroiliac joint pain, a diagnostic injection, where an anesthetic is injected directly into the SI joint under image guidance, is often considered the most definitive way to confirm the source of the pain. Consultation with specialists, such as orthopedic surgeons or physical therapists, is standard to formulate a treatment plan based on these confirmatory findings.