A positive Bragard test is evidence of nerve root compression, which may lie between L4 and S1.
Sensitivity & Specificity
A study 1 to assess the diagnostic accuracy of a Bragard test compared with the straight leg raise (SLR) test in patients presenting with electrodiagnostic evidence of L5 and S1 nerve root compression, the Sensitivity & Specificity of this test was:
Dull, nonspecific pain in the posterior thigh radiating into the knee is attributable to stretching of the hamstrings and should not be assessed as a Lasegue sign.
A sensation of tension in the calf may be attributable to thrombosis, thrombophlebitis, or contracture of the gastrocnemius.
The Bragard sign can be used to test whether the patient is malingering. The sign is usually negative in malingerers.
Homayouni K, Jafari SH, Yari H. Sensitivity and Specificity of Modified Bragard Test in Patients With Lumbosacral Radiculopathy Using Electrodiagnosis as a Reference Standard. J Chiropr Med. 2018 Mar;17(1):36-43. doi: 10.1016/j.jcm.2017.10.004. Epub 2018 Jan 12. PMID: 29628807.
Marquardt W. Karl Bragard [Karl Bragard]. Z Orthop Ihre Grenzgeb. 1973 Jun;111(3):338-9. German. PMID: 4269946.
Clinical Tests for the Musculoskeletal System 3rd Edition.