Lasègue sign (straight leg raise) and Bragard sign !

Maneuver

Lifting the straight leg of a person lying down: pain that shoots down the back of the leg means a lumbar nerve root is irritated.

Updated 2026-11-01

See it in 3D: Sciatic nerve · L5 nerve root · S1 nerve root · L4–L5 disc · L5–S1 disc · L4 nerve root · Tibial nerve

What it is

The Lasègue maneuver passively raises the straight leg to stretch the sciatic nerve and the L5 and S1 roots. If a disc herniation is compressing them, the patient's usual sciatic pain appears. The Bragard sign (foot dorsiflexion) confirms it, and a positive crossed Lasègue makes a herniation very likely. It is the key maneuver in low back pain that spreads into the leg.

The anatomy it tests

Raising the straight leg stretches the sciatic nerve and pulls the L5 and S1 roots, which slide a few millimetres in their foramina.
If a herniated disc compresses or inflames the root, this sliding hurts and the pain follows the course of the sciatic nerve.
Foot dorsiflexion (Bragard) adds tension through the tibial nerve, a branch of the sciatic nerve.
Raising the healthy leg (crossed sign) also pulls the opposite root toward the midline, against a central or axillary herniation.
Bending the knee slackens the sciatic nerve: if the pain goes away, the source is neural and not the hip.

How to do it

Patient supine and relaxed, head supported, both legs straight.
The examiner puts one hand under the heel and the other on the knee to keep it straight, and slowly raises the leg by flexing the hip.
Stop when pain appears and note the angle and where it hurts: the target is pain running down the back of the thigh to below the knee.
Positive for root tension: it reproduces the patient's usual sciatic pain between about 30 and 70 degrees of elevation.
Bragard: from the angle of pain, lower the leg a few degrees until the pain eases, then passively dorsiflex the foot.
Positive Bragard: the pain returns with dorsiflexion.
Crossed Lasègue: raise the healthy leg the same way; it is positive if pain appears in the affected leg.
Finish with strength, knee and ankle reflexes and L4, L5 and S1 sensation, comparing both sides.

What a positive result means

Positive between about 30 and 70 degrees: tension on an L5 or S1 root, mostly from an L4-L5 or L5-S1 disc herniation.
Pain below about 30 degrees: the root is barely stretched yet; think of another cause or a non-organic component.
Pain above about 70 degrees: usually from tight hamstrings, the hip or the lumbar joints, not the root.
Pain only in the low back or only in the back of the thigh does not count as a positive Lasègue.
Positive crossed Lasègue: suggests a large or central herniation.
A negative Lasègue does not rule out lumbar spinal stenosis or high herniations (L2 to L4), which are tested with the prone femoral nerve stretch.
Saddle anesthesia, sphincter changes or progressive weakness: cauda equina syndrome, an emergency.

Usefulness and limits

The Lasègue test is sensitive but not specific for disc herniation: a negative result helps rule out root tension.
The crossed Lasègue is insensitive but highly specific: a positive result makes herniation very likely.
Agreement between examiners is moderate; MRI is kept for neurological deficit, red flags or pain that does not improve.

Test yourself

Think of the answer, then tap the question to see it.

Between which angles does a positive Lasègue suggest root tension?

Between about 30 and 70 degrees of leg elevation, when it reproduces sciatic pain running below the knee.

What is the crossed Lasègue sign and what is it worth?

Pain in the affected leg when the healthy leg is raised. It has low sensitivity but high specificity for disc herniation, often a large or central one.

How is the Bragard maneuver done?

The raised leg is lowered a few degrees until the pain eases and the foot is dorsiflexed; if the pain returns, it supports root tension.

Which reflex is affected in an S1 radiculopathy?

The ankle (Achilles) reflex, which may be reduced or absent.

Why is pain that starts above 70 degrees usually not radicular?

Because by then the roots have already slid almost as far as they can; the pain usually comes from the hamstrings, the hip or the lumbar joints.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

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Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Lasègue's Sign (Journal of Clinical and Diagnostic Research (PubMed Central), 2017); Musculo-Skeletal Examination – Lower Back Exam – Practical Guide to Clinical Medicine (UC San Diego School of Medicine, 2026).

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Representative model, for educational purposes only.