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.
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.
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
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.
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
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
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.
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
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
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
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.”
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.
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
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
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
A common prone sequence:
Client lies prone.
Stabilise the pelvis.
Slowly flex the knee on the tested side.
Ask the client to report symptom onset and location.
If appropriate, add gentle hip extension.
Compare symptoms with the client’s familiar complaint.
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.
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
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.”
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
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.
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
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.
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
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
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.
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.
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.
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.
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
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 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 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
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
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
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.
They are closely related terms. The Prone Knee Bend Test is a common version of the Femoral Nerve Tension or Stretch Test.
It is commonly used to assess the femoral nerve pathway and upper lumbar nerve roots, especially L2, L3 and L4.
No. It can support suspicion when symptoms and neurological findings match, but it does not diagnose radiculopathy on its own.
Quadriceps tightness, hip flexor tightness, anterior hip pain, knee pain, lumbar extension sensitivity or guarding may all create symptoms that are not primarily neural.
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.
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.
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.
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
