Jerk Test
- Fysiobasen
- Oct 3
- 2 min read
The Jerk Test is a clinical examination used to identify postero-inferior instability of the glenohumeral joint and may also indicate a posterior labral lesion¹. It is a highly specific maneuver that reproduces posterior subluxation and relocation of the humeral head, making it a valuable tool for assessing instability-related shoulder pathology.
Procedure
Patient position
The patient sits upright.
Stabilization
The examiner stabilizes the scapula with one hand.
The other hand holds the patient’s elbow with the arm placed in 90° abduction and internal rotation¹.
Axial compression
A proximal axial force is applied along the humerus to compress the humeral head into the glenoid².
Movement
While maintaining compression, the examiner horizontally adducts the arm across the patient’s body¹.
Interpretation
Positive test: A sudden jerk or clunk occurs when the humeral head slides off the posterior rim of the glenoid.
A second clunk may occur when the arm is returned to the starting position, as the humeral head relocates¹².
Diagnostic accuracy
Sensitivity: 73 %
Specificity: 98 %
Positive likelihood ratio (+LR): 34.71
Negative likelihood ratio (−LR): 0.27³⁴
These values indicate that the Jerk Test is highly specific, making it very reliable for confirming postero-inferior instability and posterior labral pathology. However, due to moderate sensitivity, it should be combined with other instability and labral tests to improve diagnostic confidence.
Clinical relevance
High specificity: A positive test strongly suggests posterior labral involvement or postero-inferior instability.
Combination use: Best applied alongside other labral and instability tests (e.g., Kim Test, Load-and-Shift Test).
Rehabilitation value: May help guide treatment decisions, especially for athletes with posterior shoulder instability.
Summary
The Jerk Test is a simple yet highly specific examination tool for detecting posterior labral tears and postero-inferior glenohumeral instability.
A positive finding (jerk/clunk) is strongly confirmatory.
A negative test reduces but does not fully exclude instability.
Should be combined with other tests and imaging when indicated.
References
Kim et al. Painful Jerk Test:& A Predictor of Success in Nonoperative Treatment of Posteroinferior Instability of the Shoulder.& Am J Sports Med 2004 32: 1849
Jerk Test (CR) Available from: https://www.youtube.com/watch?v=mn7f6KVvScE [last accessed 27/2/2021]
Munro et al. The validity and accuracy of clinical tests used to detect labral pathology of the shoulder- a systematic review. Man Ther. 2009 Apr;14(2):119-30
Dhir J, Willis M, Watson L, Somerville L, Sadi J. Evidence-Based Review of Clinical Diagnostic Tests and Predictive Clinical Tests That Evaluate Response to Conservative Rehabilitation for Posterior Glenohumeral Instability: A Systematic Review. Sports Health. 2018;10(2):141-145.
