Piriformis syndrome can be defined by a quartet of symptoms and signs. Many physical tests have been described, but the accuracy of these tests and the symptoms cannot be concluded from studies to date. Straight leg raising does not rule out the diagnosis. Piriformis syndrome is at a stage previously encountered with herniated intervertebral disc: that piriformis muscle pathology can cause sciatica has been demonstrated, but its prevalence among low back pain and sciatica sufferers and the diagnostic accuracy of clinical features requires cross-sectional studies free of incorporation and verification biases. One small cross-sectional study provides an encouraging example of how such studies could be conducted but would need replication in a broader population and better reporting.

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