Lasègue sign, also known as Straight Leg Raise test (SLR)  is positive when there is a sensation of pain by applying pressure to the Piriformis muscle and his tendon, particularly when the hip is flexed at an angle of 90 degrees and the knee is extended. The pain or tenderness is often localized in the vicinity of the greater sciatic notch. 
Patient supine, examiner standing at the tested side with the distal hand around the subject's heel and proximal hand on subject's distal thigh(anterior) to maintain knee extension
Examiner slowly raises the leg until/tightness noted or full ROM is obtained. Slowly lower the leg until the pain or tightness resolves, at which point dorsiflex the ankle and have subject flex the neck
Leg and/or low back occurring with dorsiflexion and or neck flexion is indicative of dural involvement and/or sciatic nerve irritation
Lack of pain reproduction with dorsiflexion and/or neck flexion is indicative of hamstring tightness or sacroiliac pathology
In clinical practice the outcome test is interpreted with respect to two variables
- the maximum angle between the leg and the horizontal plane to which the can be lifted
- the pain that is provoked by the movement.
- Devillé Walter L. J. M. et al. The test of Lasègue : Systematic review of the Accuracy in Diagnosing Herniated Discs. Spine Nov 2000; 25 (9) : 1140-1147 (A1)
- Shah S,Wang TW. Piriformis syndrome. eMedicine specialities :Sports medicine : hip 2009fckLRhttp://emedicine.medscape.com/article/87545-overview
- Kirschner JS, Foye PM, Cole JL. Piriformis syndrome, diagnosis and treatment. Muscle Nerve Jul 2009 ; 40(1) : 10-18
- Lori A, Boyajian- O’ Neill et al. Diagnosis and Management of Piriformis syndrome : an osteopathic approach. The journal of the American and osteopathic association Nov 2008; 108(11): 657-664.
- Surendra UK, Shaila SK. Lasegue sign. Journal of Clinical and Diagnostic Research. 2017, VOL-11(5): RG01-RG02.72(12):959-66.
- Goeken LN, Hof AL. Instrumental straight-leg raising: a new approach to Lasegue's test. Archives of physical medicine and rehabilitation. 1991 Nov 1;