Posterior Drawer test of the shoulder is used to test for Posterior Instability. It was first described by C.Gerber and R.Ganz in 1984. 1
How it’s Performed?
The patient in supine position.
The examiner uses one hand to guide the humeral head, placing the thumb on the anterior humeral head and the fingers on the scapular spine, posterior humeral head, and scapular spine and posterior glenoid if necessary.
With the other hand the examiner holds the patient’s arm in 90° of flexion at about 20 to 30° of horizontal extension.
The examiner exerts pressure on the anterior humeral head with the thumb while simultaneously holding the arm in horizontal flexion and applying axial posterior compression in slight internal rotation.
What does a positive Posterior Drawer Test of the shoulder mean?
Where there is sufficient laxity in the capsular ligaments, this test will provoke a posterior drawer (subluxation or dislocation of the humeral head).
Horizontal extension, slight external rotation of the arm , and additional posteroanterior pressure applied by the finger to the posterior aspect of the humeral head will suffice to reduce the humeral head.
The snap that accompanies reduction must be carefully distinguished from anterior subluxation.
The important thing is to assess the motion of the humeral head relative to the glenoid fossa by placing the index finger posteriorly around the glenoid and pressing the humeral head in an anteroposterior direction with the thumb.
The examination may also be performed with the patient seated. With the patient in a relaxed posture bending slightly forward with the arm hanging alongside the trunk, the examiner places his or her thumb on the patient’s scapular spine or posterior glenoid and grasps the humeral head anteriorly. Applying rotation and pressure with the fingers will provoke posterior subluxation of the head where there is sufficient laxity in the capsular ligaments.
In posterior instability, the humeral head can be posteriorly displaced by one-half its diameter.
C Gerber, R Ganz. Clinical assessment of instability of the shoulder. With special reference to anterior and posterior drawer tests. J Bone Joint Surg Br. 1984 Aug;66(4):551-6. doi: 10.1302/0301-620X.66B4.6746691. PMID: 6746691.
Clinical Tests for the Musculoskeletal System, Third Edition