How is strength testing performed in the physical exam of rotator cuff injuries?

Updated: Oct 25, 2018
  • Author: Gerard A Malanga, MD; Chief Editor: Craig C Young, MD  more...
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Perform strength testing to isolate the relevant muscles individually.

The anterior cuff (subscapularis) can be assessed using the lift-off test, which is performed with the arm internally rotated behind the back.

Lifting the hand away from the back against resistance tests the strength of the subscapularis muscle.

The posterior cuff (infraspinatus and teres minor) is isolated best in 90° of forward flexion with the elbow flexed to 90°, testing external rotation.

Significant weakness in external rotation is observed in large rotator cuff tears.

Using either of 2 techniques described in the literature can test the supraspinatus muscle. Jobe and Moynes suggested that the best position for isolating the supraspinatus is with the elbow extended, the shoulder in full internal rotation, and the arm in the scapular plane (thumbs down position). [20]

In another report, Blackburn et al recommended testing in the prone position, with the elbow extended and the shoulder abducted to 100° and externally rotated while the patient lifts in abduction (thumbs up position). [17]

Malanga et al noted that although both techniques significantly activate the supraspinatus muscle, neither truly isolates this muscle for testing because other muscles are active in both positions. [21]

Dropping of the arm in either position usually indicates a significant supraspinatus muscle tear. More subtle weakness may represent early degeneration of the rotator cuff.

Testing of the scapula rotators (trapezius and serratus anterior) is also important. Serratus anterior weakness can be observed by having the patient lean against a wall. Winging of the scapula as the patient pushes against the wall indicates serratus anterior weakness.

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