Shoulder Orthopaedic Test: Jerk Test

The Jerk Test assesses whether posterior loading of the shoulder produces a painful clunk, jerk or familiar posterior instability symptoms. A positive result may support posterior shoulder instability reasoning when it reproduces the client’s familiar symptoms. Contemporary posterior shoulder instability reviews describe the Jerk Test, Kim Test, posterior stress test and posterior drawer as useful clinical manoeuvres, but interpretation should remain based on history, symptoms and related findings.

Introduction

A contact sport athlete reports shoulder pain or a slipping sensation when blocking, pushing or landing on an outstretched arm. Another client describes posterior shoulder clicking, catching or loss of confidence during pressing or cross-body loading.

The Jerk Test can help assess whether posterior loading reproduces a painful jerk or instability-type symptom. The key is whether the response is familiar and symptomatic, not simply whether the shoulder makes a noise.

Quick Summary

Test name: Jerk Test
Body region: Glenohumeral joint, posterior shoulder
Purpose: Assess posterior shoulder instability or posterior labral symptom response
Positive finding: Painful clunk, jerk, posterior subluxation or familiar posterior instability symptoms
Negative finding: No familiar symptoms or abnormal posterior response
Best used with: Kim Test, posterior drawer, load and shift, posterior stress test, shoulder ROM and instability history
Key limitation: It does not diagnose a posterior labral tear on its own

What Is the Jerk Test?

The Jerk Test is a posterior shoulder instability provocation test. The shoulder is usually flexed and internally rotated while the professional applies an axial load and moves the arm horizontally across the body.

A positive response is often described as a painful jerk or clunk as the humeral head subluxes or relocates posteriorly.

Why It Is Used

The test is used when posterior shoulder instability or posterior labral involvement is part of the assessment.

It may help assess clients with:

Posterior shoulder pain
Pain with pressing or pushing
Contact sport symptoms
Cross-body loading pain
Shoulder slipping or clunking
Posterior instability history
Symptoms after posteriorly directed shoulder load

What It Assesses

The test assesses symptom response to posterior glenohumeral loading. It does not directly visualise the posterior labrum, capsule or glenoid.

A positive response may reflect posterior instability, posterior labral involvement, pain sensitivity or other intra-articular symptoms.

Who It Is Useful For

This test may be useful for contact sport athletes, weightlifters, gym clients, overhead athletes and clients with posterior shoulder pain, clunking or instability symptoms.

When to Use This Test

Use when posterior instability is part of the clinical reasoning and the client can tolerate the shoulder position safely.

When Not to Use or When to Be Cautious

Use caution with acute dislocation, recent traumatic instability, severe pain, high apprehension, recent surgery, suspected fracture or inability to tolerate shoulder flexion and internal rotation.

Equipment Required

Treatment table or chair
Pain and symptom scale
Measurz recording workflow
Optional comparison side notes

Step-by-Step Protocol / Practice

Setup

Position the client sitting or supine depending on the selected method.

Client position

The shoulder is positioned in forward flexion, commonly around 90 degrees, with internal rotation.

Examiner position

Stand beside the tested shoulder.

Hand placement

One hand stabilises the scapula or shoulder girdle. The other supports the elbow or distal humerus.

Stabilisation

Control the scapula and trunk. Avoid sudden force.

Movement or force direction

Apply axial load through the humerus while moving the arm horizontally across the body. The manoeuvre creates posterior shoulder loading.

Instructions

Ask the client to report pain, clunking, slipping, catching, instability, apprehension and whether symptoms are familiar.

Positive finding

A positive finding is a painful jerk, clunk, posterior subluxation sensation or familiar posterior instability symptoms.

Negative finding

A negative finding is no familiar symptoms or abnormal posterior response.

Stopping criteria

Stop if pain increases sharply, apprehension occurs, instability symptoms are strong, guarding prevents testing or the position is not tolerated.

Safety notes

Do not force the shoulder into a painful clunk. Record pain, clunk and instability separately.

Positive and Negative Test Interpretation

A positive Jerk Test may support posterior shoulder instability reasoning when it produces a painful jerk, clunk or familiar instability symptoms.

Painless clicking or movement should be recorded but should not automatically be treated as a positive instability finding.

A negative test does not exclude posterior instability, especially when symptoms are sport-specific, load-specific or fatigue-related.

Interpretation is stronger when combined with Kim Test, posterior drawer, load and shift, posterior stress test, shoulder ROM, strength testing and instability history.

Sensitivity, Specificity and Diagnostic Accuracy

The Jerk Test is used to assess possible posterior shoulder instability or posterior labral involvement. Research suggests it has moderate sensitivity and very high specificity, meaning a positive test is useful for increasing suspicion of posterior instability or labral pathology. However, it should not be used on its own. It is best interpreted alongside the client’s history, symptoms, range of motion, strength testing, the Kim Test, and other shoulder assessments.

Research suggests the Jerk Test is better for confirming posterior shoulder instability or labral involvement than ruling it out.

Reported diagnostic values include:

• Sensitivity: 73%

• Specificity: 98%

• Positive predictive value: 88%

• Negative predictive value: 95%

Reliability and Validity

A 2024 review of posterior shoulder instability described the Jerk Test and Kim Test as provocative examination manoeuvres and highlighted that posterior instability may present with pain, reduced strength or endurance and mechanical symptoms such as clicking or popping.

Reliability depends on shoulder position, axial load, horizontal adduction force, scapular stabilisation, symptom criteria and examiner experience.

Common Errors and Limitations

Common errors include treating painless clicking as positive, forcing the shoulder, not recording symptom familiarity, failing to stabilise the scapula, not comparing with related posterior instability tests and using the test as diagnostic proof.

Limitations include client guarding, pain irritability, variable posterior instability presentation, natural laxity, overlap with labral symptoms and limited current single-test accuracy evidence.

Practical Applications

Use the Jerk Test to document posterior shoulder response to loaded cross-body movement. It may help guide further posterior instability assessment, strength testing and return-to-sport decisions.

How to Record This in Measurz

Record test name, side tested, result, pain score, symptom location, clunk or jerk present, instability sensation, shoulder position, force direction, familiar symptoms, comparison side, guarding, confidence in result and reason for stopping.

Add related findings such as Kim Test, load and shift, posterior drawer, posterior stress test, shoulder ROM, strength and sport-specific symptoms.

Related Tests / Internal Links

Kim Test
Load and Shift Test
Posterior Drawer Test
Jobe’s Relocation Test
Apprehension Test
Shoulder ROM Tests
Shoulder Strength Testing
Closed Kinetic Chain Upper Extremity Test

FAQs

What does the Jerk Test assess?

It assesses posterior shoulder response to loaded cross-body movement.

What is a positive Jerk Test?

A positive result is a painful jerk, clunk, posterior subluxation sensation or familiar posterior instability symptoms.

Is painless clicking positive?

Not by itself. Clicking is more meaningful when painful and familiar.

Can it diagnose a posterior labral tear?

No. It may support clinical reasoning but does not diagnose a tear on its own.

What should be recorded?

Record side, pain, clunk, instability sensation, shoulder position, force direction and symptom familiarity.

Key Takeaways

The Jerk Test assesses posterior shoulder instability symptoms.
Painful familiar clunking is more meaningful than painless noise.
It should not be used as a stand-alone diagnostic test.
Use it with Kim Test and other posterior instability findings.
Measurz should capture pain, clunk, position and stopping reason.

References

Codding, J. L., & Keener, J. D. (2024). Clinical, diagnostic, and therapeutic characteristics of posterior shoulder instability. Current Reviews in Musculoskeletal Medicine.

Kim, S. H., Park, J. S., Jeong, W. K., & Shin, S. K. (2005). The Kim test: A novel test for posteroinferior labral lesion of the shoulder—A comparison to the jerk test. The American Journal of Sports Medicine, 33(8), 1188–1192. https://doi.org/10.1177/0363546504272687

Kramer, J., et al. (2020). Shoulder conditions: Traumatic instability and laxity. FP Essentials, 492, 11–19.