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.

Introduction

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.  

Quick Summary

• 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

What Is the Patellar Grind Test?

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.

Why It Is Used

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.  

What It Assesses

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

Who It Is Useful For

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

When to Use This Test

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.

When Not to Use or When to Be Cautious

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

Equipment Required

• Treatment table or plinth
• Pain scale
• Symptom recording notes
• Measurz recording workflow
• Optional comparison-side notes

Step-by-Step Protocol / Practice

Setup

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 Position

• Client lies on their back
• Tested knee is relaxed
• Knee is extended or near full extension
• Quadriceps begin relaxed
• Foot and hip remain relaxed

Examiner / Professional Position

• Stand beside the tested knee
• Face the client so you can observe their response
• Maintain controlled hand contact throughout the test

Hand Placement

• Place the web space or fingers near the superior border of the patella
• Apply gentle pressure to resist superior patellar movement
• Avoid excessive compression

Stabilisation

Monitor for:

• quadriceps guarding
• hip rotation
• whole-leg tension
• withdrawal
• facial expression
• breath holding

The test should be controlled and stopped if symptoms escalate.

Movement or Force Direction

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.

Instructions

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.”

Positive Finding

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.

Negative Finding

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

Stopping Criteria

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

Safety Notes

• 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

Positive and Negative Test Interpretation

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.

Sensitivity, Specificity and Diagnostic Accuracy

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 and Validity

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 and Limitations

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

Practical Applications

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.

How to Record This in Measurz

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

Related Tests / Internal Links

• 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

FAQs

What does the Patellar Grind Test assess?

It assesses symptom response during patellofemoral compression with quadriceps contraction.

What is another name for the Patellar Grind Test?

It is also called Clarke’s test, Clarke’s sign or the patellofemoral compression test.

What is a positive Patellar Grind Test?

A positive result may involve familiar anterior knee, retropatellar or peripatellar pain during the test.

Does a positive test confirm patellofemoral pain?

No. A positive result may support assessment reasoning, but it does not confirm patellofemoral pain or cartilage pathology on its own.

Is pain alone enough to call the test positive?

Pain should be recorded, but it is more meaningful when it reproduces the client’s familiar symptoms.

How accurate is the Patellar Grind Test?

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.  

What tests should it be used with?

It is best used with squatting, stair assessment, step-down testing, patellar tracking, range of motion, strength assessment and a clear symptom history.

Key Takeaways

• 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.

References

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