The FABER test, an abbreviation for Flexion, Abduction, and External Rotation, is a common orthopedic maneuver used by clinicians to assess the source of pain in the hip, groin, or lower back. It functions as a screening tool to help differentiate between possible issues originating from the hip joint itself and those stemming from the adjacent sacroiliac (SI) joint or surrounding soft tissues. By passively moving the leg into a specific position, the test mechanically stresses these structures, providing the examiner with valuable initial information. This simple, non-invasive assessment helps guide healthcare providers toward a potential diagnosis before ordering more complex imaging studies.
Defining the FABER Test and Its Purpose
The name FABER is an acronym that precisely describes the three movements performed at the hip joint during the test. The procedure begins with the patient lying flat on their back.
The clinician gently guides the tested leg into a flexed, abducted, and externally rotated position. This movement is designed to place mechanical stress on both the anterior hip capsule and the sacroiliac joint, which connects the sacrum to the pelvis.
The characteristic positioning of the leg, with the foot resting on the opposite knee, causes the tested limb to resemble the shape of the number four, which is why it is also commonly referred to as the Figure-4 test. The primary purpose of the test is to provoke the patient’s familiar pain, which helps the clinician pinpoint the potential anatomical source of discomfort.
Interpreting Pain Location During the Test
A positive FABER test is defined by the reproduction of the patient’s pain or a noticeable restriction in the hip’s range of motion compared to the opposite side. The knee of the tested leg normally drops almost parallel to the examination table. An inability to achieve this range of motion, even without pain, suggests soft tissue tightness or joint stiffness.
The location where the patient feels pain during the maneuver is the most important factor for interpretation. Pain felt deep in the groin or anterior hip suggests a problem within the hip joint itself. Discomfort reported in the posterior buttock or directly over the sacrum indicates stress on the sacroiliac joint, pointing toward potential dysfunction in that region.
Conditions Suggested by a Positive Result
The specific location of the pain during a positive FABER test suggests a particular category of pathology. Anterior hip or groin pain points toward intra-articular hip conditions, meaning the problem lies within the joint capsule.
Intra-Articular Hip Conditions
These findings are commonly associated with issues like hip osteoarthritis (deteriorated joint cartilage) or a labral tear (involving the ring of cartilage lining the hip socket). Another frequent cause of anterior pain is femoroacetabular impingement (FAI), a condition where abnormal bone growth causes the hip to rub together during movement.
Sacroiliac and Referred Pain
If the patient reports pain concentrated in the posterior pelvis, the indication shifts to sacroiliac joint dysfunction or inflammation (sacroiliitis). Reproducing the patient’s pain in this area suggests the SI joint is the primary pain generator. Less commonly, pain felt in the lower back during the maneuver can suggest referred pain originating from the lumbar spine. This requires the clinician to consider conditions like lumbar radiculopathy, where an irritated nerve root causes pain that radiates into the hip area.
Follow-Up After a Positive Indication
The FABER test is a provocative screening tool and does not provide a definitive diagnosis on its own. A positive indication suggests a high probability of involvement in the hip or SI joint, but further investigation is always necessary to confirm the exact underlying condition. Clinicians often use the FABER test in combination with other orthopedic tests in a cluster to increase diagnostic accuracy, particularly for SI joint issues.
The next step typically involves diagnostic imaging. This may include X-rays to assess for bone spurs or signs of osteoarthritis. An MRI may be ordered to visualize soft tissues like the labrum for tears or to better evaluate inflammation. In cases where SI joint dysfunction is suspected, a targeted, image-guided anesthetic injection into the joint can be used as a final diagnostic confirmation. If the injection temporarily relieves the pain, it confirms the SI joint as the source. Consultation with a specialist, such as an orthopedic surgeon or a physical therapist, is then needed to formulate a treatment plan based on the confirmed diagnosis.