The straight leg raise, also called Lasègue’s sign, Lasègue test or Lazarević’s sign, is a test done during the physical examination to determine whether a patient with low back pain has an underlying herniated disk, often located at L5 (fifth lumbar spinal nerve).
With the patient lying down on his or her back on an examination table or exam floor, the examiner lifts the patient’s leg while the knee is straight.
A variation is to lift the leg while the patient is sitting. However, this reduces the sensitivity of the test.
In order to make this test more specific, the ankle can be dorsiflexed and the cervical spine flexed. This increases the stretching of the nerve root and dura.