What is SLR Test?

Straight Leg Raise (SLR) Test: A Vital Tool in Lumbar Radiculopathy Assessment

Introduction

The Straight Leg Raise (SLR) Test is a cornerstone in orthopedic and neurological clinical examinations used primarily to assess lumbar nerve root irritation, particularly sciatic nerve involvement. Whether you're a physiotherapist, orthopedic specialist, or general practitioner, understanding the correct execution and interpretation of this test can significantly aid in diagnosing lumbar disc herniation, sciatica, and other lumbosacral pathologies.

Purpose of the Test

The main goal of the SLR test is to reproduce radicular symptoms (pain, tingling, or numbness radiating down the leg) by putting tension on the sciatic nerve and its spinal nerve roots (typically L4, L5, S1). This helps determine whether a patient's leg pain originates from nerve root compression or another cause.

Anatomical Basis

The sciatic nerve is the largest nerve in the body, formed by the lumbosacral nerve roots (L4–S3). During the SLR test, hip flexion stretches this nerve pathway. If any structure (like a herniated disc) compresses the nerve roots, stretching the nerve recreates the characteristic pain pattern down the posterior leg.

Patient Positioning

  • The patient lies supine (on their back) on an examination table.

  • The lower limbs are extended, with the examiner standing to the side.

Procedure

  1. Passive SLR:

    • The examiner gently lifts the affected leg by the heel, keeping the knee extended.

    • Hip flexion is increased gradually.

    • The test is usually stopped at the point of pain or about 70° of hip flexion.

  2. Pain Response:

  3. Confirmatory Maneuvers:

Interpretation

Variants of the SLR Test

  • Crossed SLR Test (Contralateral SLR):

    • Lifting the unaffected leg reproduces symptoms in the affected leg.

    • Highly specific for lumbar disc herniation.

  • Seated SLR Test (Slump Test):

    • Performed with the patient in a seated position to catch malingering or verify findings.

Clinical Significance

The SLR test is highly sensitive (approximately 91%) for detecting lumbar disc herniation causing radiculopathy, although its specificity is lower (around 26%). It is often used in combination with other tests and patient history for accurate diagnosis.

Conditions Commonly Diagnosed Using SLR Test

  • Lumbar disc herniation

  • Sciatica

  • Piriformis syndrome (in differential diagnosis)

  • Lumbosacral radiculopathy

  • Malingering (via non-anatomic pain patterns)

Advantages

  • Simple and quick to perform.

  • Requires no special equipment.

  • Non-invasive and repeatable.

Limitations

  • Not highly specific—positive results can also appear in hip or pelvic issues.

  • Subject to variation based on patient tolerance and examiner technique.

Conclusion

The Straight Leg Raise Test remains a critical diagnostic tool for evaluating lower back and leg pain due to nerve root compression. While not definitive on its own, its high sensitivity makes it an essential part of a comprehensive neuro-orthopedic assessment. Used wisely, it can guide clinical reasoning and enhance the accuracy of lumbar spine evaluations.

FAQ: Straight Leg Raise (SLR) Test

Q1: What does a positive SLR test mean?

A positive test typically indicates sciatic nerve root compression, most often due to a lumbar disc herniation.

Q2: Can tight hamstrings cause a false positive?

Yes, but true neural pain is usually sharp, radiating, or electric, while hamstring tightness causes dull stretching pain.

Q3: How is the SLR test different from the Lasegue’s Test?

They are often used interchangeably, but Lasegue’s test refers more specifically to adding dorsiflexion after reaching a positive SLR range.

Q4: Can the SLR be used in children?

Yes, but interpretation requires caution. Younger patients may have naturally tighter hamstrings.

Q5: Is the test painful?

It may cause reproduction of symptoms if nerve irritation exists, but it should not be forcefully painful.

References

  1. Vroomen PC, et al. (2000). Diagnostic accuracy of history and physical examination in patients suspected of lumbar radiculopathy. J Neurol Neurosurg Psychiatry, 68(4): 430–436.

  2. Majlesi J, Togay H, Unalan H, Toprak S. (2008). The sensitivity and specificity of the Slump and the Straight Leg Raising tests in patients with lumbar disc herniation. J Clin Rheumatol, 14(2): 87–91.

  3. Kendall FP, et al. (2005). Muscles: Testing and Function with Posture and Pain. 5th ed.

  4. Physiopedia. Straight Leg Raise Test. https://www.physio-pedia.com/Straight_Leg_Raise_Test


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