Bowstring Sign
Purpose
The Bowstring sign is a passive provocative clinical test performed in patients presenting with low back pain to determine the sacroiliac nerve tension. It is also known as the Cram Test, the popliteal compression test or the Posterior Tibial Nerve test.[1]
There are references to 2 different bowstring signs test in literature. R.H. Cram describes, what will be discussed here as the Bowstring test, when he performed experiments to test the compression of the posterior tibial nerve in the popliteal space with a refinement of the straight leg raise test.[2]
The Jacques Forestier bowstring sign is something first noticed by a doctor named Jacques Forestier in people with early ankylosing spondylitis (a condition that causes stiffness and pain in the spine). Normally, when someone bends sideways, the muscles on the side they’re bending toward are relaxed. But in people with early AS, the muscles on that side stay tight and firm, almost like a stretched bowstring. Bringing attention back to this simple physical sign could help doctors catch AS sooner, even before it shows up on scans.[3]
Technique
Patient Position
The patient is in a supine position without a pillow.
Therapist Position
The examiner stands at the tested side with a face facing towards the patient's face.
Procedure
- Initially, the examiner performs the Straight Leg Raise (SLR) test in which the examiner lifts the leg with the extended knee. Examiner raises the leg to the point where the patient perceives pain along the distribution lumbosacral dermatomal level or when maximum flexion is achieved.
- While performing the SLR test, at the point of maximum pain (positive SLR), the examiner will slightly flex the patient’s knee approximately 20 degrees, thereby reducing the pain.
- The examiner applies pressure (via thumb) on the popliteal fossa on the sciatic nerve (Posterior Tibial Nerve).
- If this elicits the same pain as the patient experiences during SLR, then the Bowstring sign is said to be positive.[4]
- This test should be performed on both legs, the normal side being the first.
Evidence
- The bowstring sign is one of the commonly used variants of the SLR test, and a study published in 2020 suggests using SLRT, Femoral nerve tension test, Slump test, and bowstring test in combination. This takes about 2 minutes and could improve both the sensitivity and specificity of the physical examination for the diagnosis of sciatica.[6]
- There is no evidence regarding the psychometric properties of the Bowstring sign.
References
- ↑ Das JM, Nadi M. Lasegue Sign. StatPearls [Internet]. 2020 May 24.
- ↑ Cram, R. H. (1953). A sign of sciatic nerve root pressure. The Journal of Bone & Joint Surgery British Volume, 35(2), 192-195.
- ↑ 1. Masi AT, Sierakowski S, Kim JM. Jacques Forestier’s vanished bowstring sign in ankylosing spondylitis: a call to test its validity and possible relation to spinal myofascial hypertonicity. Clinical and experimental rheumatology [Internet]. 2005;23(6):760–6. Available from: https://pubmed.ncbi.nlm.nih.gov/16396691/
- ↑ Kamath, S. U., & Kamath, S. S. (2017). Lasègue's Sign. Journal of clinical and diagnostic research : JCDR, 11(5), RG01–RG02. https://doi.org/10.7860/JCDR/2017/24899.9794
- ↑ Sports Injuries And Rehabilitation. Bowstring test. Available from:https://www.youtube.com/watch?v=dEX43YHaOxQ. [Lasted accessed: 26th Feb 2021]
- ↑ Berthelot JM, Darrieutort-Laffite C, Arnolfo P, Glémarec J, Le Goff B, Maugars Y. Inadequacies of the Lasègue test, and how the Slump and Bowstring tests are useful for the diagnosis of sciatica. Joint bone spine. 2020 Jun 16:105030.