Piriformis Test

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Definition/Description

The Piriformis test is a lower limb provocation test to evaluate the impact of the piriformis muscle on the sciatic nerve. 

Clinically Relevant Anatomy

Piriformis is a flat muscle and is one of the hip lateral rotators. The origin is on the facies pelvina (anterior side) of the Os sacrum and has a insertion at the superior aspect of the trochanter major of the femur. The piriformis muscle is running over the top of the sciatic nerve. This muscle has the function of external rotation, abduction and extension in the hip and it is also important to stabilize the joint of the hip. And is innervate by the direct branches from the sacral plexus (L5-S2). 

Sciatic nerve or also named as N. Ishiadicus ,passes behind the hip joint to the muscles lying underneath. Above the knee joint, the sciatic nerve splits into two branches: N. Tibialis and the N. Fibularis communis. The sciatic nerve passes over or under the piriformis muscle but it is also possible that the sciatic nerve passes, partially or whole, trough the piriformis muscle. This depends from person to person.

Purpose

The piriformis test is used to screen the piriformis muscle and to detect tightness of the muscle or other discomforts of the sciatic nerve as it passes through or under the Piriformis muscle. Because this is a muscle and neurological test.

Technique

The Piriformis test can be performed in two methods:

1. Piriformis test in side-lying position: For performing the test, the patient is positioned in side-lying on the unaffected side. The symptomatic leg is positioned in 60 to 90 degrees of flexion in the hip and 90 degrees flexion in the knee joint. The patient should be lying with the face directed towards the examiner, The examiner’s hand is placed on the pelvis to stabilize it, The other hand is placed on the lateral side of the knee. The examiner gives hand pressure on the lateral side of the knee and tries to stretch the part as far as possible. The examiner performs a horizontal adduction while putting pressure on the knee in the direction of the table. During the stretch the patient may feel pain or discomfort.This test is also named as the FAIR test (Flexion Adduction and Internal Rotation).
   
2. Seated Piriformis Test: The piriformis test can also be examined in seated position on the table/chair. In the seated piriformis test where the client have a flexion of 90 degrees in the hip and also 90 degrees in the knee. One hand of the examiner is going to placed on the lateral side of the client knees. The examinator will ask the client to perform a horizontal abduction while the examinator will offer resistance against it.

Results of the test

When the patient has complains of pain in the piriformis muscle region or in other words the buttocks. This may be related to the sciatic nerve that passes through this muscle or that it has become pinched by the piriformis muscle. The Freiburg sing is a pain signal that occurs when the sciatic nerve is irritated. This pain will occur when the examinated leg will move in a passive horizontal adduction. If these symptoms occur; we can speak of a piriformis syndrome. In this syndrome, we speak of pain or numbness in the buttock and posterior thigh with occasional radiation into the foot. Another possible cause for the clamping of the nerve ichiadicus are trigger points in the piriformis muscle.

Key Research

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A study was performed by Fishman et al. that determine the sensitivity and specificity of the piriformis test.

Sensitivity = .88²     -LR = .14

Specificity = .83²    +LR = 5.2

Resources

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Clinical Bottom Line

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Recent Related Research (from Pubmed)

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References

1. Flynn, T, Cleland, J, Whitman, J. Users' Guide to the Musculoskeletal Examination. (2008) pg 238
2. Fishman, L, Dombi, G, Michaelson, C, Ringel, S. Piriformis syndrome: Diagnosis, treatment and outcome- a 10 year study. Arch Phys Med Rehabil 2002; 83:295-301.
3. Fishman, L, Zybert, P. Electrophysiologic evidence of piriformis syndrome. Arch Phys Med Rehabil 1992; 73:359-364.
4. Prentice, W.E. (2003) Arnheim's principles of athletic training: A competency based approach. 11th edition. McGraw-Hill Higher Education, New York.
5. David Magee. (2002) Orthopedic Physical Assessment. 2002. 4th edition. Published by WB Suanders.
6. ↑ VENU AKUTHOTA & STANLEY A. HERRING (Editors), 2009, Nerve and vascular injuries in sports medicine, Springer, New York, 203p.
7. ↑ SANDRA J. SHULTZ & PEGGY A. HOUGLUM & DAVID H. PERRIN, Third edition 2010, Examination of musculoskeletal injuries, Human Kinetics, Leeds, 698p.
8. ↑ Londers J, Van Melkebeek J. Hip arthroscopy: outcome and patient satisfaction after 5 to 10 years. Acta Orthop Belg. 2OO7;73(4): 478-83
9. ↑ SCHUNCKE M, SCHULTE E, SCHUMACHER U, VOLL M, WESKER K. Derde oplage 2008, Anatomische atlas Prometheus algemene anatomie en bewegingsapparaat, Bohn Stafleu van Loghum, Houten, p543
10. ↑ CURTIS W. SLIPMAN, DERBY R, FREDERICK A. SIMEONE & TOM G, 2008, Interventional Spine: An algorithmic approach, Saunders, Philadelphia, 1454p.
11. ↑ M. Lynn Palmer & Marcia E. EPLER, Second edition 1998, Fundamentals of Musculoskeletal Assessment Techniques,Lippincott Williams & Wilkins ,432p