The straight leg raise is a test that can be performed during a physical examination, with the leg being lifted actively by the patient or passively by the clinician. If the straight leg raise is done actively by the patient it is a test of functional leg strength, particularly the rectus femoris element of the quadriceps (checking both hip flexion and knee extension strength simultaneously). If carried out passively (also called
Lasègue's sign, Lasègue test or Lazarević's sign), it is used to determine whether a patient with
low back pain
Low back pain (LBP) or lumbago is a common disorder involving the muscles, nerves, and bones of the back, in between the lower edge of the ribs and the lower fold of the buttocks. Pain can vary from a dull constant ache to a sudden sharp feeli ...
has an underlying nerve root sensitivity, often located at L5 (fifth
lumbar
In tetrapod anatomy, lumbar is an adjective that means ''of or pertaining to the abdominal segment of the torso, between the diaphragm and the sacrum.''
The lumbar region is sometimes referred to as the lower spine, or as an area of the back i ...
spinal nerve). The rest of this article relates to the passive version of the test.
Technique
With the patient lying down on their 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
In anatomy, cervical is an adjective that has two meanings:
# of or pertaining to any neck.
# of or pertaining to the female cervix: i.e., the ''neck'' of the uterus.
*Commonly used medical phrases involving the neck are
**cervical collar
**cervic ...
spine
flexed. This increases the stretching of the nerve root and dura.
Interpretation
If the patient experiences
sciatic pain, and more specifically pain radiating down the leg (
radiculopathy
Radiculopathy, also commonly referred to as pinched nerve, refers to a set of conditions in which one or more nerves are affected and do not work properly (a neuropathy). Radiculopathy can result in pain (radicular pain), weakness, altered sensati ...
), when the straight leg is at an angle of between 30 and 70 degrees, then the test is positive and a herniated disk is a possible cause of the pain.
A negative test suggests a likely different cause for back pain.
A positive straight leg test reproduces radiating leg pain. If it only causes back pain, then the test is negative. Because this is often misunderstood, it is prudent to add a statement of clarification. For example, "Straight leg test is positive on the left, reproducing the patient's radiating leg symptoms."
A
meta-analysis
A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analyses can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting me ...
reported the accuracy as:
*
sensitivity 91%
*
specificity 26%
If raising the opposite leg causes pain (cross or contralateral straight leg raising):
* sensitivity 29%
* specificity 88%
Lasègue's sign
Lasègue's sign was named after
Charles Lasègue
Ernest-Charles Lasègue (5 September 1816–20 March 1883) was a French physician that released over one hundred scientific papers. He became recognized in the mid-19th century from his work in the fields of psychiatry and neurology. He publi ...
(1816–1883). In 1864 Lasègue described the signs of developing low back pain while straightening the knee when the leg has already been lifted. In 1880 Serbian doctor
Laza Lazarević
Lazar "Laza" Lazarević ( sr-cyr, Лазаp Лаза Лазаревић, 13 May 1851 – 10 January 1891) was a Serbian writer, psychiatrist, and neurologist.
Medical career
Lazarević was born in Šabac in 1851. He studied medicine at the Un ...
described the straight leg raise test as it is used today, so the sign is often named Lazarević's sign in Serbia and some other countries.
Lazarevićev znak
See also
* Femoral nerve stretch test
Femoral nerve stretch test, also known as Mackiewicz sign, is a test for spinal nerve root compression, which is associated with disc protrusion and femoral nerve injury.
__TOC__ Uses
The femoral nerve stretch test can identify spinal nerve root ...
References
{{Orthopedic examination
Symptoms and signs: Nervous system
Medical signs
Musculoskeletal examination