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
The rectus femoris muscle is one of the four quadriceps muscles of the human body. The others are the vastus medialis, the vastus intermedius (deep to the rectus femoris), and the vastus lateralis. All four parts of the quadriceps muscle attach ...
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 or wiktionary:lumbago#Etymology, lumbago is a common musculoskeletal disorders, 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 var ...
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 (anatomy), diaphragm and the sacrum.
Naming and location
The lumbar region is sometimes referred to as the lowe ...
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 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 se ...
), 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.
A
meta-analysis
Meta-analysis is a method of synthesis of quantitative data from multiple independent studies addressing a common research question. An important part of this method involves computing a combined effect size across all of the studies. As such, th ...
reported the straight-leg test as having:
*
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 (1816–1883). In 1864 Lasègue's medical student J.J. Forst 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 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
References
{{Orthopedic examination
Symptoms and signs: Nervous system
Medical signs
Musculoskeletal examination