Shoulder
Instability
Evidence: confirmed
Jerk Test (Posterior) Special Test
Orthopedic Physical Examination & Clinical Assessment Guide
What is it used for?
- Diagnosing Posterior Instability.
How to Perform
- Position: Seated. Arm flexed 90°, Internally Rotated.
- Action: Apply axial load (push back) while horizontally adducting the arm.
Interpretation of Results
- Positive Test: A sudden 'clunk' or jerk as the humeral head subluxes posteriorly.
Diagnostic Accuracy
- Sensitivity: 73%
- Specificity: 98%
Clinical Context & Limitations
The Jerk Test (Posterior) should be considered as one component of a comprehensive musculoskeletal assessment. No single special test has perfect diagnostic accuracy; thus, clinical decision-making should integrate test results with patient-reported symptoms, mechanism of injury, functional impairment, and relevant imaging.
Clinicians should be aware of potential false-positive results in patients with pain sensitisation, muscle guarding, or poor relaxation. For the Shoulder region, combining the Jerk Test (Posterior) with complementary examination tests significantly improves overall diagnostic confidence.
References
- Magee, D. J. (2021). Orthopedic Physical Assessment.
