Piriformis Syndrome Test is used in the assessment of a contracture of the piriformis muscle or to detect compression of the sciatic nerve by the piriformis.
The patient lies in the lateral position with the test leg uppermost. The patient flexes the hip of that leg to 60° with the knee flexed. The examiner stabilizes the hip with one hand and applies downward pressure to the knee.
If the piriform is is tight, pain is elicited in the muscle. If the piriformis is pinching the sciatic nerve, pain results in the buttock and the patient may experience sciatica.
The FAIR Test (flexion, adduction, and internal rotation test) is a similar test for Piriformis Syndrome Test that is designed to detect compression of the sciatic nerve by the piriformis.
The patient is positioned in supine with the involved extremity by the clinician. Holding the patient’s knee, the clinician brings the involved extremity into a position of hip flexion, adduction, and internal rotation.
If pain is elicited at a point corresponding to the intersection of the sciatic nerve and the piriformis during this test, the result is considered positive.
The FAIR test has been demonstrated to have a sensitivity of 88% and a specificity of 83%.
See Also: Thomas Test of the Hip
The piriformis Muscle is an external rotator of the hip at less than 60 degrees of hip flexion. At 90 degrees of hip flexion, the piriformis muscle reverses its muscle action, becoming an internal rotator and abductor of the hip.
This muscle arises from the anterior aspect of the S2, S3, and S4 segments of the sacrum; the capsule of the SIJ; and the sacrotuberous ligament. It exits from the pelvis via the greater sciatic foramen, before attaching to the upper border of the greater trochanter of the femur.
In around 80% of cases, the sciatic nerve travels below the piriformis muscle. While in 17% of people, the piriformis muscle is pierced by parts or all of the sciatic nerve.
Piriformis syndrome is the result of entrapment of the sciatic nerve by the piriformis muscle, as it passes through the sciatic notch.
Multiple etiologies have been proposed to explain the compression or irritation of the sciatic nerve that occurs with the piriformis syndrome:
Hypertrophy of the piriformis muscle.
Overuse of the piriformis muscle: Although there is disagreement, overuse seems to be the most common cause of piriformis syndrome. This suggests that patients must be effectively cautioned about returning too quickly to the type of activity that bought about the piriformis syndrome once recovered.
Trauma: Trauma, direct or indirect, to the sacroiliac or gluteal region can lead to piriformis syndrome and is a result of hematoma formation and subsequent scarring between the sciatic nerve and the short external rotators.
Hip flexion contracture: A flexion contracture at the hip has been associated with piriformis syndrome. This flexion contracture increases the lumbar lordosis, which increases the tension in the pelvic–femoral muscles, as these muscles try to stabilize the pelvis and spine in the new position. This increased tension causes the involved muscles to hypertrophy with no corresponding increase in the size of the bony foramina, resulting in neurological signs of sciatic compression.
Gender: Females are more commonly affected by this syndrome, with as much as a 6:1 female-to-male
Pseudoaneurysm of the inferior gluteal artery.
Excessive exercise to the hamstring muscles.
Inflammation and spasm of the piriformis muscle: This is often in association with trauma, infection, and
anatomical variations of the muscle.
Anatomical anomalies: In 1938, anomalies of the piriformis muscle, with a subsequent alteration in the relationship between the piriformis muscle and the sciatic nerve, were implicated in sciatica Local anatomical anomalies may contribute to the likelihood that symptoms will develop. Patients with this condition report radicular pain that is much like the nerve-root pain associated with lumbar disk disease with movement of the hip. These patients typically present with a history of gluteal trauma, symptoms of pain in the buttock and intolerance to sitting, tenderness to palpation of the greater sciatic notch, and pain with flexion, adduction, and internal rotation of the hip.
Symptoms of Piriformis syndrome include:
Conservative treatmenta include:
Robinson listed six cardinal features of piriformis syndrome: