FAIR Test | Piriformis Syndrome | Deep Gluteal Syndrome of the Hip

Deep gluteal syndrome, abbreviated as DGS is defined as pain in the buttock area caused by a non-discogenic entrapment of the sciatic nerve in the subgluteal space.

The structures that can be involved in sciatic nerve entrapment are not only the piriformis but also fibrous bands containing blood vessels, gluteal muscles, hamstring muscles, the gemelli-obturator internus complex, vascular abnormalities and space-occupying lesions. For this reason, the term “deep gluteal syndrome” instead of “pirformis syndrome” is now preferred.

Commonly reported symptoms include hip or buttock pain and tenderness in the gluteal and retro-trochanteric region. The pain is often described to be sciatica-like, often unilateral and exacerbated with rotation of the hip in flexion and knee extension. Other symptoms include intolerance of sitting for more than 20 to 30 minutes, limping, disturbed or loss of sensation in the affected extremity and pain at night getting better during the day.

Fishman et al. (2002) compared the FAIR test with its ability to delay the Hoffmann-reflex, also called H-reflex, which is a sensitive, but not specific measure for nerve conduction. They found a sensitivity of 88% and a specificity of 83% for the FAIR test when using a delay of 3 standard deviations above the normal H-reflex. As the H-reflex is not an accurate gold standard and no other studies have been conducted on this test, we give it a questionable clinical value in practice.

Before you conduct the test, make sure you have examined and excluded more prevalent pathologies in the lumbar spine and SI joint that could explain the patient’s symptoms.
To perform the test as shown in the study of Fishman, have the patient lie on the unaffected side with his upper hip flexed to 90 degrees, maximal adduction and the upper knee flexed to 90 degrees. While both acetabula are kept vertical apply upward and lateral pressure to the shin while passively rotating the hip internally to 45 degrees or as near as the patient can tolerate.

This test is positive if the patient reports pain at the intersection of the sciatic nerve and the piriformis.

Other common tests to assess for deep gluteal syndrome are:

• Freiberg Sign
• Pace Maneuver
• Seated Piriformis Stretch Test
• Heel Contralateral Knee (HCLK) Maneuver 
• Piriformis Test
• Beatty Maneuver
• Active Piriformis Test

21 OF THE MOST USEFUL ORTHOPAEDIC TESTS IN CLINICAL PRACTICE

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References

Fishman, L. M., Dombi, G. W., Michaelsen, C., Ringel, S., Rozbruch, J., Rosner, B., & Weber, C. (2002). Piriformis syndrome: diagnosis, treatment, and outcome—a 10-year study. Archives of physical medicine and rehabilitation, 83(3), 295-301.

Fishman, L. M., & Zybert, P. A. (1992). Electrophysiologic evidence of piriformis syndrome. Archives of physical medicine and rehabilitation, 73(4), 359-364.

Kirschner, J. S., Foye, P. M., & Cole, J. L. (2009). Piriformis syndrome, diagnosis and treatment. Muscle & nerve, 40(1), 10-18.