The Femoral Nerve Tension Test, also called the Femoral Nerve Stretch Test, Prone Knee Bend Test or Reverse Lasègue Test, is a neurodynamic assessment used to assess whether hip extension and knee flexion reproduce familiar anterior thigh or upper lumbar radicular-type symptoms. A positive test may support suspicion of femoral nerve or L2–L4 nerve-root mechanosensitivity when it matches the client’s history, neurological screen and related findings. It does not diagnose lumbar radiculopathy, femoral neuropathy or disc pathology on its own.

Introduction

Anterior thigh pain can come from several sources. It may be related to the lumbar spine, femoral nerve, hip joint, quadriceps, iliopsoas, knee, referred pain patterns or local soft tissue sensitivity.

The Femoral Nerve Tension Test is a clinical neurodynamic test used to assess whether loading the anterior thigh and femoral nerve pathway reproduces the client’s familiar symptoms.

It is also known as:

• Femoral Nerve Stretch Test
• Prone Knee Bend Test
• Reverse Lasègue Test
• Anterior Femoral Nerve Test
• L2–L4 nerve root stretch test

The test is commonly used when assessing suspected upper lumbar radicular symptoms or femoral nerve mechanosensitivity. NICE describes the femoral stretch test as a test used to assess for upper lumbar disc herniation, performed with the client prone by flexing the knee and extending the leg, with a positive test reproducing leg pain.  

Quick Summary

• Test name: Femoral Nerve Tension Test
• Also known as: Femoral Nerve Stretch Test, Prone Knee Bend Test, Reverse Lasègue Test
• Region: Lumbar spine, hip, anterior thigh
• Test type: Neurodynamic / symptom provocation test
• Common position: Prone or side-lying
• Primary movement: Knee flexion with hip extension or stabilised hip position
• Positive finding: Reproduction of familiar anterior thigh, groin or upper lumbar radicular-type symptoms
• Negative finding: No familiar neural-type symptoms reproduced
• Best used with: Neurological screen, lumbar assessment, hip assessment, reflexes, myotomes, dermatomes and symptom history
• Key limitation: It should not be used as a stand-alone diagnostic test

What Is the Femoral Nerve Tension Test?

The Femoral Nerve Tension Test is a neurodynamic test that loads the femoral nerve and upper lumbar nerve-root region by positioning the hip and knee to tension the anterior thigh pathway.

A common version is performed in prone:

• the client lies face down
• the examiner flexes the knee
• hip extension may be added or controlled
• symptoms are monitored in the anterior thigh, groin or lumbar region

The test is considered the anterior equivalent of the Straight Leg Raise because it targets the anterior thigh and femoral nerve pathway rather than the posterior sciatic pathway. Physiopedia describes the prone knee bending test as a neural tension test used to stress the femoral nerve and mid-lumbar L2–L4 nerve roots.  

Why It Is Used

The Femoral Nerve Tension Test is used to explore whether anterior thigh symptoms may be influenced by femoral nerve or upper lumbar nerve-root mechanosensitivity.

It may help professionals:

• reproduce familiar anterior thigh symptoms
• distinguish neural-type symptoms from quadriceps stretch
• assess symptom response to knee flexion and hip extension
• support reasoning around L2–L4 involvement
• decide whether further neurological screening is needed
• monitor symptom irritability over time
• compare left and right responses
• record neurodynamic findings in Measurz

It is most useful when combined with:

• lumbar spine assessment
• hip assessment
• neurological screen
• patellar reflex
• quadriceps strength
• hip flexor strength
• dermatomal sensation
• symptom distribution
• femoral nerve or lumbar-related history
• related tests such as SLR, Slump or Bowstring when appropriate

What It Assesses

The Femoral Nerve Tension Test may assess:

• femoral nerve mechanosensitivity
• upper lumbar nerve-root mechanosensitivity
• anterior thigh symptom reproduction
• symptom response to hip extension and knee flexion
• irritability of anterior thigh or upper lumbar radicular-type symptoms
• ability to differentiate familiar symptoms from simple quadriceps stretch

It may be associated with:

• suspected L2–L4 radicular symptoms
• anterior thigh referred symptoms
• femoral nerve mechanosensitivity
• upper lumbar disc-related symptoms
• anterior hip or thigh symptoms requiring differential assessment

It does not directly assess or confirm:

• lumbar disc herniation
• femoral neuropathy
• exact nerve-root level
• femoral nerve entrapment
• hip pathology
• quadriceps pathology
• tissue damage
• need for imaging
• readiness to return to sport or work

Who It Is Useful For

The Femoral Nerve Tension Test may be useful for:

• exercise professionals
• strength and conditioning coaches
• allied health support teams
• movement assessment professionals
• sport and performance staff
• students learning neurodynamic assessment
• professionals using Measurz or MAT for structured assessment recording

It may be relevant for clients with:

• anterior thigh pain
• groin or upper thigh symptoms
• symptoms linked with low back pain
• suspected upper lumbar radicular-type symptoms
• altered sensation in the anterior thigh
• symptoms affected by lumbar extension or prone positions
• symptoms provoked by hip extension or knee flexion
• reduced quadriceps strength or altered patellar reflex where clinically relevant

Use within scope. Progressive neurological symptoms, severe weakness, major sensory change, saddle symptoms, bladder or bowel changes, unexplained severe pain or systemic signs require appropriate medical review.

When to Use This Test

Use the Femoral Nerve Tension Test when you want to assess whether anterior thigh or upper lumbar symptoms are reproduced by femoral nerve pathway loading.

It may be used during:

• low-back-related anterior thigh pain assessment
• suspected upper lumbar radiculopathy assessment
• neurodynamic assessment education
• hip and lumbar differential screening
• reassessment of symptom irritability
• monitoring response to rehabilitation or activity modification

It may be especially useful when the client reports symptoms such as:

• anterior thigh pain
• burning, tingling or altered sensation in the anterior thigh
• low back pain with anterior thigh symptoms
• symptoms aggravated by lumbar extension
• symptoms affected by prone lying, walking or hip extension
• symptoms that do not fit a sciatic distribution

When Not to Use or When to Be Cautious

Use caution or avoid testing when the client reports:

• severe or worsening neurological symptoms
• progressive weakness
• significant numbness or major sensory change
• saddle anaesthesia
• bladder or bowel changes
• unexplained weight loss, fever or systemic symptoms
• recent significant trauma
• suspected fracture
• severe hip or lumbar pain at rest
• recent surgery without appropriate clearance
• highly irritable symptoms likely to flare with testing

Stop the test if:

• symptoms become severe
• symptoms spread unexpectedly
• neurological symptoms increase
• the client feels unsafe
• the client asks to stop
• the position is not tolerated
• further medical review is more appropriate

Equipment Required

No specialised equipment is usually required.

Useful resources include:

• plinth or firm surface
• pain rating scale
• body chart
• neurological screen record
• Measurz recording workflow
• optional goniometer or inclinometer for knee flexion or hip extension angle
• optional symptom irritability notes

Step-by-Step Protocol / Practice

Setup

Explain the test before starting.

Example wording:

“We are going to position your hip and knee to gently load the front of the thigh and femoral nerve pathway. The goal is to see whether this reproduces your familiar symptoms. This does not diagnose the cause on its own, but it helps us understand your symptom response.”

Client Position

Common options include:

• Prone: client lies face down with hips neutral
• Side-lying: client lies on the unaffected side, useful if prone is not tolerated

Prone is commonly described in diagnostic and clinical resources. NICE describes the test with the client prone, flexing the knee and extending the leg.  

Examiner / Professional Position

Stand beside the tested leg.

Ensure you can:

• control knee flexion
• control hip extension if added
• stabilise the pelvis
• monitor symptoms
• stop quickly if symptoms increase too much

Hand Placement

For a prone version:

• one hand may stabilise the pelvis or sacrum
• the other hand controls the distal lower leg or ankle
• flex the knee gradually
• add hip extension only if appropriate and tolerated

For a side-lying version:

• stabilise the pelvis
• hold the tested leg behind the client
• move the hip into extension and knee into flexion gradually

Stabilisation

Stabilise to reduce compensation:

• prevent excessive anterior pelvic tilt
• prevent lumbar extension if it changes the test question
• avoid hip abduction or rotation drift
• keep movement controlled
• compare with the other side if appropriate

Movement Sequence

A common prone sequence:

1. Client lies prone.
2. Stabilise the pelvis.
3. Slowly flex the knee on the tested side.
4. Ask the client to report symptom onset and location.
5. If appropriate, add gentle hip extension.
6. Compare symptoms with the client’s familiar complaint.
7. Ease the position if symptoms increase too much.

Some protocols use knee flexion first; others add hip extension to increase femoral nerve loading. The key is to record exactly which sequence was used.

Movement Direction

The main movement components are:

• passive knee flexion
• optional hip extension
• pelvic stabilisation
• symptom-guided loading

The movement should be:

• slow
• controlled
• not forced
• stopped if symptoms become severe
• distinguished from normal quadriceps stretch

Instructions

Ask the client:

• “Tell me when you first feel anything.”
• “Where do you feel it?”
• “Is it your familiar symptom?”
• “Is it stretch, pain, tingling, numbness, burning or pulling?”
• “Rate the symptom from 0 to 10.”
• “Tell me if it becomes too uncomfortable.”

Positive Finding

A positive Femoral Nerve Tension Test is usually:

• reproduction of the client’s familiar anterior thigh, groin or upper lumbar radicular-type symptoms during knee flexion and/or hip extension

More meaningful symptoms may include:

• familiar anterior thigh pain
• burning or tingling
• altered sensation
• symptoms not explained by simple quadriceps stretch
• symptoms that change with sensitising or easing movement
• symptoms matching the client’s usual complaint

Negative Finding

A negative test is usually:

• no reproduction of familiar anterior thigh or neural-type symptoms

The client may still feel:

• quadriceps stretch
• hip flexor stretch
• local knee discomfort
• non-familiar anterior thigh tension

These should not automatically be recorded as a positive neural finding.

Stopping Criteria

Stop if:

• symptoms are severe
• symptoms spread or worsen significantly
• neurological symptoms increase
• the client reports distress
• the client cannot relax
• the position is not tolerated
• symptoms are unclear and repeated testing is not appropriate

Safety Notes

The test should be performed slowly and respectfully.

Avoid repeated provocation of severe anterior thigh symptoms. In highly irritable presentations, use a lower-range version, record available response or defer the test.

Positive and Negative Test Interpretation

Positive Test

A positive Femoral Nerve Tension Test means the test reproduces the client’s familiar anterior thigh, groin or upper lumbar radicular-type symptoms.

A positive result may increase suspicion of:

• femoral nerve mechanosensitivity
• L2–L4 nerve-root involvement
• upper lumbar radicular-type symptoms
• anterior thigh neural sensitivity

A positive result is more meaningful when it matches:

• anterior thigh symptom distribution
• neurological findings
• quadriceps weakness where relevant
• altered patellar reflex where relevant
• dermatomal sensory changes
• symptom change with lumbar movement
• history consistent with upper lumbar involvement

A positive result does not confirm:

• lumbar radiculopathy
• disc herniation
• femoral neuropathy
• femoral nerve entrapment
• exact spinal level
• need for imaging
• need for surgery

Other factors may contribute to symptoms, including:

• quadriceps tightness
• hip flexor tightness
• anterior hip symptoms
• knee pain
• lumbar extension sensitivity
• high irritability
• guarding

Negative Test

A negative test means the position does not reproduce familiar anterior thigh or neural-type symptoms.

A negative result may reduce suspicion of femoral nerve pathway mechanosensitivity if:

• neurological screen is normal
• lumbar movement does not reproduce symptoms
• hip assessment suggests another source
• symptoms are not in an anterior thigh pattern
• related tests are also negative

However, a negative result does not fully exclude:

• upper lumbar radiculopathy
• intermittent nerve-root irritation
• femoral nerve involvement
• symptoms that only occur with load, walking, extension or fatigue
• other causes of anterior thigh symptoms

Sensitivity, Specificity and Diagnostic Accuracy

Diagnostic accuracy evidence for the Femoral Nerve Tension Test is more limited than for lower lumbar radicular tests such as Straight Leg Raise, partly because upper lumbar radiculopathies are less common.

Upper Lumbar Radiculopathy

A systematic review of clinical neurological examination for lumbosacral radiculopathy reported that the femoral nerve stretch test had sensitivity of 1.00 with a wide 95% confidence interval of 0.40–1.00 and specificity of 0.83 with a 95% confidence interval of 0.52–0.98. The authors also noted a scarcity of diagnostic accuracy studies, meaning the results should be interpreted cautiously.  

Prone Knee Bend / L2–L4 Nerve-Root Compression

A clinical summary of Suri et al. reported the prone knee bend test had sensitivity of 50% and specificity of 100% for lumbar disc herniation with L2–L4 nerve-root compression, and sensitivity of 70% and specificity of 88% for L3 nerve-root involvement specifically.  

These values suggest that a positive test may be more useful for increasing suspicion in selected presentations, while a negative test may not be enough to rule out upper lumbar involvement.

MRI-Based Radicular Symptom Studies

A study of clinical tests and MRI findings in people with chronic unilateral radicular symptoms reported that, in general, individual neurodynamic tests lacked diagnostic accuracy for MRI-verified disc extrusion or high-grade nerve compression. It also noted that femoral neurodynamic test comparisons were based on a smaller subgroup.  

Practical Diagnostic Accuracy Summary

For the Femoral Nerve Tension Test:

• Condition or presentation: suspected upper lumbar radiculopathy, L2–L4 involvement or femoral nerve mechanosensitivity
• Population: usually selected low-back-related leg pain or suspected radiculopathy cohorts
• Reference standards: variable, including MRI, electrodiagnosis or clinical neurological findings
• Sensitivity: variable and often based on small samples
• Specificity: may be moderate to high in selected studies
• Best use: supporting suspicion when positive and clinically consistent
• Main limitation: limited high-quality evidence and wide confidence intervals

How to Interpret This

A positive test may increase suspicion of upper lumbar nerve-root or femoral nerve mechanosensitivity when it matches the client’s symptom pattern and neurological findings.

A negative test does not fully exclude upper lumbar radicular involvement, especially when the history and neurological screen remain suggestive.

Reliability and Validity

Reliability evidence for the exact Femoral Nerve Tension Test is limited compared with more commonly studied lower-limb neurodynamic tests.

Validity is strongest when the test is interpreted with:

• symptom distribution
• neurological screen
• patellar reflex
• quadriceps strength
• dermatomal sensation
• lumbar movement response
• hip and knee assessment
• comparison side
• imaging or electrodiagnostic information where available

A 2025 study using prone knee bend and femoral slump testing emphasised that femoral nerve neurodynamic assessment was designed to evaluate movement-based sensitivity phenomena rather than diagnose nerve entrapment or neuropathy. This supports cautious interpretation of positive neurodynamic findings.  

A 2023 anatomical study described the Femoral Nerve Stretch Test as an important neurodynamic test for assessing mechanical sensitivity of the femoral plexus associated with L2, L3 and L4 nerve-root disorders.  

Reliability is stronger when you standardise:

• client position
• knee flexion angle
• hip extension angle
• pelvic stabilisation
• lumbar position
• speed of movement
• symptom wording
• side tested first
• pain rating method
• criteria for a positive test

Common Errors and Limitations

Common errors include:

• calling the test diagnostic on its own
• recording quadriceps stretch as a positive neural test
• not asking whether symptoms are familiar
• failing to stabilise the pelvis
• allowing uncontrolled lumbar extension
• adding hip extension too aggressively
• not recording knee flexion angle
• not recording symptom location
• not performing a neurological screen
• ignoring hip or knee contributors
• repeatedly provoking severe symptoms

Limitations include:

• upper lumbar radiculopathy is less common than lower lumbar radiculopathy
• diagnostic accuracy evidence is limited
• confidence intervals are wide in some studies
• quadriceps and hip flexor tightness can mimic symptoms
• hip and knee pain can confound interpretation
• test methods vary across studies and clinicians
• a negative result does not rule out upper lumbar involvement
• a positive result does not identify the exact structure or level

Practical Applications

The Femoral Nerve Tension Test can support:

• anterior thigh symptom assessment
• upper lumbar radicular-type symptom reasoning
• hip versus lumbar differential assessment
• neurodynamic assessment education
• symptom irritability tracking
• structured Measurz recording
• decisions about whether further neurological assessment is needed

It may help guide discussion around:

• walking tolerance
• lumbar extension tolerance
• prone lying tolerance
• hip extension sensitivity
• anterior thigh symptoms
• training or sport movements involving hip extension
• whether further assessment or referral is needed

It is less useful when:

• symptoms are clearly local quadriceps stretch only
• knee pain limits test position
• symptoms are highly irritable
• neurological red flags are present
• the assessment question is return-to-sport clearance

How to Record This in Measurz

Record:

• test name: Femoral Nerve Tension Test / Femoral Nerve Stretch Test / Prone Knee Bend
• side tested: left or right
• test version: prone, side-lying or modified
• result: positive, negative, unclear or unable to test
• knee flexion angle or available range
• hip position: neutral, extended or degree of extension
• lumbar/pelvic position
• pain score
• symptom location:
  • anterior thigh
  • groin
  • anterior knee
  • lumbar spine
  • hip
  • other
• symptom quality:
  • stretch
  • pain
  • burning
  • tingling
  • numbness
  • pulling
• whether symptoms are familiar
• whether symptoms match the main complaint
• comparison side
• neurological findings:
  • quadriceps strength
  • hip flexor strength
  • patellar reflex
  • dermatomes
  • sensory changes
• related tests:
  • lumbar movement assessment
  • Straight Leg Raise
  • Slump Test
  • Bowstring Sign
  • Bragard Sign
  • hip assessment
• irritability
• guarding or compensation
• reason for stopping, if relevant
• confidence in result
• interpretation notes
• retest date
• referral or further assessment notes if appropriate

Recording these details improves:

• repeatability
• communication
• client education
• assessment reasoning
• monitoring over time
• team consistency
• reporting quality

Related Tests / Internal Links

• Bowstring Sign
• Bragard Sign Test
• FAIR Test
• FADIR Test
• Hip Quadrant Test
• Piriformis Test
• Craig Test
• Spine Function Index-10
• Oswestry Disability Questionnaire

FAQs

What is a positive Femoral Nerve Tension Test?

A positive test is reproduction of the client’s familiar anterior thigh, groin or upper lumbar radicular-type symptoms during knee flexion and/or hip extension.

Is the Femoral Nerve Tension Test the same as the Prone Knee Bend Test?

They are closely related terms. The Prone Knee Bend Test is a common version of the Femoral Nerve Tension or Stretch Test.

What nerve roots does the test assess?

It is commonly used to assess the femoral nerve pathway and upper lumbar nerve roots, especially L2, L3 and L4.  

Can the test diagnose upper lumbar radiculopathy?

No. It can support suspicion when symptoms and neurological findings match, but it does not diagnose radiculopathy on its own.

What can cause a false positive?

Quadriceps tightness, hip flexor tightness, anterior hip pain, knee pain, lumbar extension sensitivity or guarding may all create symptoms that are not primarily neural.

Is there sensitivity and specificity evidence?

A systematic review reported femoral nerve stretch test sensitivity of 1.00 and specificity of 0.83, but with wide confidence intervals and limited evidence. Other summaries report lower sensitivity and high specificity for selected L2–L4 compression presentations.  

What should the test be paired with?

It should be paired with neurological screening, lumbar movement assessment, hip assessment, symptom distribution, patellar reflex, quadriceps strength, dermatomes and related neurodynamic tests where relevant.

Key Takeaways

• The Femoral Nerve Tension Test assesses anterior thigh symptom response to femoral nerve pathway loading.
• It is commonly performed prone with knee flexion and optional hip extension.
• A positive finding is reproduction of familiar anterior thigh, groin or upper lumbar radicular-type symptoms.
• Quadriceps stretch alone should not automatically be recorded as positive.
• The test may support suspicion of L2–L4 or femoral nerve mechanosensitivity but does not diagnose radiculopathy on its own.
• Diagnostic accuracy evidence is limited and should be interpreted with caution.
• Measurz should record side, test version, hip and knee position, symptom location, pain score, familiar symptom response, neurological findings and related tests.

References

Cochrane. (2026). Physical examination for the diagnosis of lumbar radiculopathy due to disc herniation in patients with low-back pain and sciatica. https://www.cochrane.org/evidence/CD007431_physical-examination-diagnosis-lumbar-radiculopathy-due-disc-herniation-patients-low-back-pain-and

Ishii, K., et al. (2023). Does the L4 nerve root extend during femoral nerve stretch test? A cadaveric study. Journal of Orthopaedic Science. https://doi.org/10.1016/j.jos.2023.03.011

NICE Clinical Knowledge Summaries. (2025). Sciatica lumbar radiculopathy: Assessment. https://cks.nice.org.uk/topics/sciatica-lumbar-radiculopathy/diagnosis/assessment/

Suri, P., Rainville, J., Katz, J. N., Jouve, C., Hartigan, C., Limke, J., Pena, E., Li, L., Swaim, B., & Hunter, D. J. (2011). The accuracy of the physical examination for the diagnosis of midlumbar and low lumbar nerve root impingement. Spine, 36(1), 63–73. https://doi.org/10.1097/BRS.0b013e3181c953cc

Tawa, N., Rhoda, A., & Diener, I. (2017). Accuracy of clinical neurological examination in diagnosing lumbo-sacral radiculopathy: A systematic literature review. BMC Musculoskeletal Disorders, 18, 93. https://doi.org/10.1186/s12891-016-1383-2

Vanti, C., et al. (2025). Prevalence of femoral nerve neurodynamic disorder in patients with anterior knee pain: A cross-sectional study. BMC Musculoskeletal Disorders. https://doi.org/10.1186/s12891-025-08951-y