The Patellar Grind Test, also called Clarke’s test or Clarke’s sign, assesses symptom response during patellofemoral compression with quadriceps contraction. A positive result may suggest patellofemoral joint irritation or anterior knee pain sensitivity, but the test has limited diagnostic value and does not confirm patellofemoral pain, chondromalacia or cartilage pathology on its own.
Anterior knee pain is common in active people, athletes and general population clients.
The Patellar Grind Test is often used as part of a patellofemoral assessment to explore whether compressing the patella against the femur during quadriceps contraction reproduces symptoms.
It is commonly used alongside:
squat assessment
step-down testing
stair assessment
patellar tracking observation
patellar mobility testing
knee range of motion
quadriceps strength testing
hip strength and control assessment
Although the Patellar Grind Test is widely known, evidence suggests it should be interpreted cautiously. Patellofemoral pain diagnosis is usually based on history and symptom reproduction during functional loading tasks, and individual physical examination findings often do not consistently correlate with symptoms.
Test name: Patellar Grind Test
Also known as: Clarke’s test, Clarke’s sign, patellofemoral compression test
Body region: Knee / patellofemoral joint
Purpose: Assess symptom response to patellofemoral compression during quadriceps contraction
Commonly associated presentation: Patellofemoral pain or anterior knee pain
Positive finding: Reproduction of familiar retropatellar or peripatellar pain, apprehension or inability to contract quadriceps due to symptoms
Negative finding: No familiar pain or meaningful symptom response
Best used with: Squat, stairs, step-down, patellar tracking, ROM and strength assessment
Key limitation: Poor standalone diagnostic value; pain may occur even in people without clear patellofemoral pathology
The Patellar Grind Test is a knee special test used to assess symptom response when the patella is compressed against the femur during quadriceps contraction.
The examiner applies pressure near the superior border of the patella while the client contracts the quadriceps.
The test is intended to increase patellofemoral joint compression and may reproduce anterior knee symptoms.
The test may be used to explore:
retropatellar pain
peripatellar pain
anterior knee discomfort
quadriceps inhibition due to symptoms
pain response during patellofemoral loading
It should not be used as a stand-alone diagnostic test.
The Patellar Grind Test may help support assessment reasoning when patellofemoral joint symptoms are suspected.
It may help professionals:
assess anterior knee symptom response
compare the symptomatic and non-symptomatic knee
document pain during patellofemoral compression
identify whether symptoms are familiar to the client
guide further functional assessment
monitor symptom irritability over time
However, the test has limited specificity and should not be used alone to determine the presence of patellofemoral pain.
The test assesses symptom response to patellofemoral compression during quadriceps contraction.
It may provide information about:
anterior knee pain sensitivity
retropatellar symptom response
peripatellar symptom response
tolerance to quadriceps contraction
side-to-side symptom difference
irritability during patellofemoral loading
It does not directly measure:
cartilage quality
chondromalacia grade
patellofemoral joint structure
tracking mechanics during function
quadriceps strength
hip control
movement quality
exact source of anterior knee pain
This test may be useful for:
exercise professionals
strength and conditioning coaches
performance coaches
rehabilitation practitioners
movement assessment professionals
students learning knee assessment
professionals using Measurz or MAT for structured assessment recording
It may be relevant for clients who report:
anterior knee pain
pain around or behind the kneecap
pain with stairs
pain with squatting
pain with prolonged sitting
pain during running or jumping
reduced confidence with loaded knee flexion
Use the Patellar Grind Test when anterior knee or patellofemoral symptoms are suspected and symptom irritability is low enough for controlled testing.
It may be useful when the client reports:
retropatellar pain
peripatellar pain
pain during squatting
pain during stair descent
pain with kneeling
pain during running hills
pain with repeated jumping or landing
The test is more meaningful when it reproduces the client’s familiar symptoms rather than vague discomfort.
Use caution with:
acute traumatic knee injury
recent patellar dislocation
large swelling or suspected haemarthrosis
suspected fracture
suspected osteochondral injury
recent knee surgery
severe pain
high irritability
marked apprehension
strong guarding
Stop testing if:
pain escalates quickly
symptoms feel unsafe
the client cannot relax
the client cannot contract the quadriceps comfortably
the client asks to stop
symptoms remain elevated after the test
Treatment table or plinth
Pain scale
Symptom recording notes
Measurz recording workflow
Optional comparison-side notes
Position the client lying supine with the knee relaxed and extended.
Explain the test clearly before starting.
The client should understand that the aim is to assess symptom response, not to forcefully compress the patella.
Client lies on their back
Tested knee is relaxed
Knee is extended or near full extension
Quadriceps begin relaxed
Foot and hip remain relaxed
Stand beside the tested knee
Face the client so you can observe their response
Maintain controlled hand contact throughout the test
Place the web space or fingers near the superior border of the patella
Apply gentle pressure to resist superior patellar movement
Avoid excessive compression
Monitor for:
quadriceps guarding
hip rotation
whole-leg tension
withdrawal
facial expression
breath holding
The test should be controlled and stopped if symptoms escalate.
Apply gentle pressure to the superior pole of the patella in an inferior or posterior-inferior direction while the client contracts the quadriceps.
The quadriceps contraction attempts to move the patella superiorly while the examiner provides resistance.
Ask the client to:
stay relaxed before the contraction
gently tighten the thigh muscle
report pain or discomfort
say whether the symptom is familiar
identify the symptom location
rate pain from 0–10
Example instruction:
“I’m going to apply gentle pressure near your kneecap while you tighten your thigh muscle. Tell me if this reproduces your familiar knee pain or if it feels different.”
A positive Patellar Grind Test may include:
reproduction of familiar anterior knee pain
retropatellar pain
peripatellar pain
inability to maintain quadriceps contraction due to symptoms
marked discomfort compared with the other side
Pain should be recorded carefully, including whether it is familiar or unfamiliar.
A negative finding involves:
no familiar anterior knee pain
no meaningful symptom reproduction
smooth quadriceps contraction
no major side-to-side difference
no protective withdrawal or guarding
Stop if:
pain becomes sharp
pain escalates quickly
the client withdraws the leg
quadriceps contraction becomes guarded
symptoms feel unsafe
the client asks to stop
Use gentle pressure only
Avoid aggressive patellar compression
Do not repeat excessively in irritable presentations
Record whether the response was familiar pain, unfamiliar pain, apprehension or no symptoms
A positive Patellar Grind Test may suggest sensitivity or irritation around the patellofemoral joint when it reproduces familiar anterior knee pain.
A positive result is more meaningful when it matches:
pain behind or around the patella
pain with squatting
pain with stair descent
pain during loaded knee flexion
pain with prolonged sitting
pain during running, jumping or landing
other patellofemoral assessment findings
A positive result does not confirm:
patellofemoral pain syndrome
chondromalacia patellae
cartilage damage
patellofemoral arthritis
exact pain source
Other factors may contribute to a positive response, including:
general knee sensitivity
high irritability
fear of pain
poor relaxation
excessive examiner pressure
soft tissue sensitivity
recent training load spike
non-patellofemoral anterior knee pain
A negative test may suggest that this specific compression and contraction position does not reproduce the client’s symptoms.
However, a negative test does not exclude patellofemoral pain or anterior knee pain.
Some clients may only report symptoms during:
squatting
stair descent
running
jumping
kneeling
loaded knee flexion
fatigue
sport-specific movement
Interpretation is stronger when the test is combined with history, symptom behaviour, functional loading tests, range of motion, strength and movement assessment.
The Patellar Grind Test has limited standalone diagnostic value.
Evidence suggests that many people may experience discomfort with this test, even when they do not have clear patellofemoral symptoms. This reduces the usefulness of the test as a stand-alone diagnostic procedure.
A commonly cited validation study for Clarke’s sign reported:
Sensitivity: 39%
Specificity: 67%
Target condition: chondromalacia patellae
Key conclusion: diagnostic validity values were unsatisfactory for assessing chondromalacia patellae
These values suggest the test should be interpreted cautiously and should not be used alone to identify chondromalacia or patellofemoral pathology.
Current patellofemoral pain guidance places stronger diagnostic value on reproduction of retropatellar or peripatellar pain during functional activities that load the patellofemoral joint, such as squatting and stair climbing or descent.
Practical interpretation:
Low sensitivity means a negative test does not reliably exclude patellofemoral pain or cartilage-related symptoms.
Modest specificity means a positive test does not strongly confirm patellofemoral pathology.
Pain during the test should be interpreted with caution.
Functional symptom reproduction is often more useful than this test alone.
The result should be combined with history, movement assessment and other findings.
Reliability may be limited because the test depends on:
examiner hand placement
amount of compression
direction of pressure
client quadriceps contraction effort
pain threshold
symptom irritability
whether familiar pain is required for a positive finding
whether the test is repeated multiple times
Several clinical sources and reviews note that many patellofemoral physical examination tests have low or inconsistent reliability, and the Patellar Grind Test has limited diagnostic validity as a stand-alone test.
Validity is stronger when:
the test reproduces familiar symptoms
the symptom location matches the client’s usual pain
functional loading tasks also reproduce symptoms
history is consistent with patellofemoral pain
other findings support the same clinical picture
Validity is weaker when:
the test causes vague discomfort only
the examiner uses excessive pressure
the client has high general pain sensitivity
symptoms do not match the client’s usual pain
no functional tasks reproduce symptoms
Common errors include:
using too much pressure
moving too quickly
repeating the test excessively
interpreting any discomfort as a positive result
failing to ask whether the pain is familiar
not recording pain location
not comparing both sides
ignoring symptom irritability
using the test as a stand-alone diagnosis
assuming a positive test means cartilage damage
Limitations include:
poor standalone diagnostic value
possible discomfort in people without patellofemoral pathology
low specificity
limited reliability
examiner pressure variability
inability to identify exact tissue source
reduced usefulness in highly irritable knees
The Patellar Grind Test may help professionals:
document anterior knee symptom response
compare sides
identify whether patellofemoral compression is provocative
support broader patellofemoral assessment reasoning
monitor symptom irritability over time
educate clients about symptom triggers
guide further functional testing
For athletes, it may be used alongside:
squat assessment
step-down testing
running assessment
landing assessment
quadriceps strength testing
hip strength testing
training load review
For general population clients, it may help explore symptoms related to:
stairs
kneeling
squatting
prolonged sitting
repeated knee bending
For Measurz users, the main value is consistent symptom recording, side-to-side comparison and linking the finding to functional tests.
Record:
test name: Patellar Grind Test / Clarke’s Test
side tested: left, right or both
result: positive, negative, unclear or unable to test
client position
knee position
pressure direction
quadriceps contraction quality
pain score from 0–10
symptom location
symptom quality
whether the symptom was familiar
whether apprehension occurred
comparison side
irritability level
reason for stopping if stopped early
related findings, such as squat pain, stair pain, step-down quality or patellar tracking
interpretation notes
planned retest date if monitoring change
Record whether the main response was:
familiar anterior knee pain
unfamiliar discomfort
apprehension
quadriceps inhibition
no symptoms
unclear response
unable to test safely
This improves:
repeatability
communication
client education
assessment reasoning
team consistency
progress monitoring
reporting quality
Patellar Apprehension Sign
Moving Patellar Apprehension Test
Patellar Tracking Assessment
J-Sign
Step-Down Test
Single-Leg Squat Test
Knee Range of Motion Tests
Sweep Test
It assesses symptom response during patellofemoral compression with quadriceps contraction.
It is also called Clarke’s test, Clarke’s sign or the patellofemoral compression test.
A positive result may involve familiar anterior knee, retropatellar or peripatellar pain during the test.
No. A positive result may support assessment reasoning, but it does not confirm patellofemoral pain or cartilage pathology on its own.
Pain should be recorded, but it is more meaningful when it reproduces the client’s familiar symptoms.
Diagnostic accuracy appears limited. A commonly cited validation study reported sensitivity of 39% and specificity of 67% for chondromalacia patellae, which is not strong enough for stand-alone diagnostic use.
It is best used with squatting, stair assessment, step-down testing, patellar tracking, range of motion, strength assessment and a clear symptom history.
The Patellar Grind Test assesses symptom response to patellofemoral compression.
It is also known as Clarke’s test or Clarke’s sign.
A positive result may suggest patellofemoral sensitivity when it reproduces familiar symptoms.
The test has limited diagnostic value and should not be used alone.
Pain during the test does not confirm cartilage damage or patellofemoral pain.
Functional loading tests such as squatting and stair descent are often more useful for patellofemoral pain assessment.
Measurz should record side, result, pain score, symptom location, familiar symptoms, pressure direction, comparison side and related functional findings.
Doberstein, S. T., Romeyn, R. L., & Reineke, D. M. (2008). The diagnostic value of the Clarke sign in assessing chondromalacia patella. Journal of Athletic Training, 43(2), 190–196. https://doi.org/10.4085/1062-6050-43.2.190
Kasitinon, D., Li, W.-X., Wang, E. X. S., & Fredericson, M. (2021). Physical examination and patellofemoral pain syndrome: An updated review. Current Reviews in Musculoskeletal Medicine, 14, 406–412. https://doi.org/10.1007/s12178-021-09730-7
Willy, R. W., Hoglund, L. T., Barton, C. J., Bolgla, L. A., Scalzitti, D. A., Logerstedt, D. S., Lynch, A. D., Snyder-Mackler, L., & McDonough, C. M. (2019). Patellofemoral pain: Clinical practice guidelines linked to the International Classification of Functioning, Disability and Health from the Academy of Orthopaedic Physical Therapy of the American Physical Therapy Association. Journal of Orthopaedic & Sports Physical Therapy, 49(9), CPG1–CPG95. https://doi.org/10.2519/jospt.2019.0302
Doyle, E. (2020). Appraisal of clinical practice guideline: Patellofemoral pain: Clinical practice guidelines linked to the International Classification of Functioning, Disability and Health from the Academy of Orthopaedic Physical Therapy of the American Physical Therapy Association. Journal of Physiotherapy, 66(2), 126. https://doi.org/10.1016/j.jphys.2020.02.008
Barton, C. J., Crossley, K. M., & Vicenzino, B. (2024). Best practice guide for patellofemoral pain based on synthesis of systematic review, expert clinical reasoning and patient perspectives. British Journal of Sports Medicine, 58(24), 1486–1495. https://doi.org/10.1136/bjsports-2024-108649
