Name of test
Deltoid Abduction Test
What it tests
The Deltoid Abduction Test assesses the function of the deltoid muscle in abducting the arm at the glenohumeral joint. If a patient presents with both impaired deltoid-mediated abduction as well as weakness in lateral rotation of the arm at the shoulder, an axillary nerve lesion should be on the differential diagnosis.
How to do it
Ask the patient to abduct the arm at the shoulder as far as possible. If the patient demonstrates a full range of motion, offer varying amounts resistance the second time around by pressing down on the arm (this may uncover a more subtle weakness).
The normal response
Under normal circumstances, the arm can be fully abducted all the way to the head (at least 180 degrees).
What it means if not normal
A failed Deltoid Abduction Test is indicated when the patient is unable to abduct the arm more than 30 degrees. The supraspinatous muscle is involved in shoulder abduction for the first 15-30 degrees, after which the deltoid begins to dominate this action. If a patient fails the Deltoid Abduction Test and also presents with weakness in laterally rotating the arm at the shoulder, and sensory impairment over a 1 inch circular area around the point of deltoid insertion, a lesion to axillary nerve is likely.
Comments
The patient may attempt to overcome a weakness in abduction by laterally rotating the arm and using the long head of the biceps to compensate.
Citations
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