It is important to apply pressure gently at first and to increase the pressure only if pain has not been triggered during the course of the test to that point.
The empty can test can be performed similarly with the humerus externally rotated, this called a full can test.
Full can test:
This test is done with the patient standing or sitting.
Similar to the empty can test, the elbow is extended and the patient’s arm is held at 90° of abduction, 30° of horizontal flexion, and in external rotation.
Then the examiner applies a pressure on the examined limb
What does a positive Empty can test mean?
When Jobe Test elicits severe pain and the patient is unable to hold his or her arm abducted 90° against gravity, this is called a positive drop arm sign.
The superior portions of the rotator cuff (supraspinatus muscle) are particularly assessed in internal rotation (with the thumb down as when emptying a can), and the anterior portions in external rotation (thumb points upward—full can).
The Jobe Test may be repeated at only 45° abduction to further differentiate the findings.
Where the impingement component predominates, there will be less pain and more strength where the tendon is still intact.
The Jobe Test can yield false-positive results where pathology of the long head of the biceps tendon is present.
If the test elicits pain and the patient is unable to abduct the arm 90° and hold it against gravity, this indicates a tear of the tendon of the supraspinatus muscle, or damage to the suprascapular nerve.
Strength in the supraspinatus muscle may not be completely diminished until over two-thirds of the tendon is torn.
Sensitivity & Specificity
A Cohort Study 1 by Nitin B Jain found that empty can test (Jobe test) had a high sensitivity and specificity for supraspinatus tears as following:
Sensitivity: 88 %
Specificity: 62 %
The full can test had higher specificity (74% vs. 68%) and an equal sensitivity of 77% when compared with the empty can test in a series of 136 patients 2.
Studies performed by anesthetizing the suprascapular and axillary nerves show that the supraspinatus and deltoid muscles are responsible for abduction of the arm.
The supraspinatus muscle, along with the other muscles of the rotator cuff , press the head of the humerus into the socket and abduct the arm for the first 20°, then the deltoid muscle comes into play.
Even if the supraspinatus muscle tendon is completely torn, the shoulder is still capable of good range of motion.
There is a deficit only at the onset of abduction and then again when the arm reaches 90° and above.
EMG tests show no difference in the EMG activity whether the arm is held in full internal rotation (classic Jobe empty can position), with the thumb pointing to the floor, or with the arm in maximum external rotation (full can position).
The strength of the supraspinatus muscle can also be tested with the elbows flexed rather than extended.
For the patient, this position requires less holding power and less stress, and is therefore also less painful.
A partial rupture of the supraspinatus tendon will result inabduction that is both weak and painful.69 A painless weakness with abduction could indicate a complete rupture of the supraspinatus tendon, although the deltoid cannot be ruled out. The tendon of the supraspinatus can be passively stretched by positioning it in adduction and IR to see if this increases the pain.
There are four rotator cuff muscles (supraspinatus, infraspinatus, teres minor, subscapularis muscles).
Its action is abducting and externally rotating the arm, providing stability to the shoulder joint.
Nitin B Jain, Jennifer Luz, Laurence D Higgins, Yan Dong, Jon J P Warner, Elizabeth Matzkin, Jeffrey N Katz. The Diagnostic Accuracy of Special Tests for Rotator Cuff Tear: The ROW Cohort Study.Am J Phys Med Rehabil. 2017 Mar. PMID: 27386812.
Itoi E, Kido T, Sano A, Urayama M, Sato K. Which is more useful, the “full can test” or the “empty can test,” in detecting the torn supraspinatus tendon? Am J Sports Med. 1999 Jan-Feb;27(1):65-8. doi: 10.1177/03635465990270011901. PMID: 9934421.
Campbel’s Operative Orthopaedics 13th Book
Clinical Tests for the Musculoskeletal System 3rd Edition.
Dutton’s Orthopaedic Examination, Evaluation, And Intervention 3rd Edition.