The Bowstring Sign of Forestier
Original Editor - Matt Huey
Top Contributors - Matt Huey and Vidya Acharya
Purpose
The Bowstring Sign of Forestier came from the observations of Jacques Forestier in 1951. He published his experiences in 200 individuals with ankylosing spondylitis.[1] This sign was described as an early detection for ankylosing spondylitis due to the atrophy of the dorsolumbar musculature.
Technique
How to assess the sign
- Expose the individuals back as to observe and/or palpate the musculature
- Have the individual facing away from you
- Have the individual perform lateral flexion of the spine to one side and then the other.
The sign is positive if the muscles on the concave side (flexed site) contract (bowstring). This can also be felt with palpation. Individuals without ankylosing spondylitis will have a contraction of the muscles on the convex side where as the concave musculature will be relaxed.
Evidence
No evidence exists on the reliability, validity, sensitivity or specificity of this sign directly. One study did look at surface EMG activity of the paravertebral musculature with lateral bending.[2] 2o individuals with confirmed AS and 3 with sacroiliitis were compared to 2o individuals with osteoarthritis and 20 normal individuals. Of the 20 with AS, 15 showed greater activity on the concave side compared to the convex.
References
- ↑ FORESTIER J, JACQUELINE F, ROTES QUEROL J: La Spondylarthrite Ankylosante: Clinique, Radiologie Anatomie Pathologique, Traitement, Masson & Cie, Paris, 1951
- ↑ SADOWSKA-WROBLEWSKA M, GARWOLINSKA H, SUWALSKA M: Electromyographic investigations on the bow-string sign in patients with ankylosing spondylitis and with degenerative joint disease of the spine. Reumatologia 1968; 6: 275-82 (in Polish).