Posterior Stress Test (or Posterior Apprehension sign) of the shoulder is used to test for Posterior Instability.
How it’s Performed?
The patient in supine position.
Place the patient’s arm in flexion, adduction, and internal rotation and apply a posteriorly directed force.
What does a positive Posterior Apprehension sign mean?
Positive if there is pain and sense of instability with the maneuver.
The most characteristic sign for a shoulder posterior dislocation is a loud clunk as the shoulder is moved from a forward flexed position into abduction and external rotation, a positive finding that is often misdiagnosed as an anterior dislocation.
The findings for a posterior dislocation are usually severe pain, limited ER, often to less than 0 degree, and limited elevation to less than 90 degrees.
Patients who have a posterior instability pattern typically report symptoms with the arm in a forward flexed, adducted position, such as when pushing open heavy doors.
There is usually a posterior prominence and rounding of the shoulder as compared to the opposite side, and a flattening of the anterior aspects of the shoulder. Looking down at the patient’s shoulders from behind can best assess these asymmetries.
Rockwood and FA . The shoulder. Philadelphia: Saunders; 1990. Matsen III. Glenohumeral instability. pp. 611–755.
María Valencia Mora, Miguel Ángel Ruiz Ibán, Jorge Diaz Heredia, Juan Carlos Gutiérrez-Gómez, Raquel Ruiz Diaz, Mikel Aramberri, and Carlos Cobiella. Physical Exam and Evaluation of the Unstable Shoulder. Open Orthop J. 2017; 11: 946–956. PMID: 29114336.
Clinical Tests for the Musculoskeletal System, Third Edition.