Jobe Test (Empty can)

 Jobe Test (Empty can)

What is Jobe Test (Empty can)?

  • Jobe Test (or Empty can test) is used to test for
    • Weakness or insufficiency of the supraspinatus muscle
    • Rotator cuff impingement

How it's Performed?

Jobe Test may be performed with the patient standing or seated.

  • With the elbow extended, the patient’s arm is held at 90° of abduction, 30° of horizontal flexion, and in internal or external rotation.
  • The examiner exerts pressure on the upper arm during the abduction and horizontal flexion motion.
  • Using electromyography, this test enables testing of the supraspinatus muscle largely in isolation.
  • 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.

What does a positive Jobe Test (Empty can) 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

  • Sensitivity: 88 %
  • Specificity: 62 %

Notes

  • 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.

Reference

  • Campbel's Operative Orthopaedics 13th Book
  • NCBI
  • Clinical Tests for the Musculoskeletal 3rd Ed. Book
  • https://pubmed.ncbi.nlm.nih.gov/27386812/



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