Shoulder Instability Tests
From
University of Washington
Laxity Tests
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These tests examine the amount of translation allowed by the shoulder starting from positions where the ligaments are normally loose.
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These are tests of
laxity,
not tests for
instability
: Many normally stable shoulders, such as those of gymnasts, will demonstrate substantial translation on these laxity tests even though they are asymptomatic.
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The amount of translation on laxity testing is determined by the length of the capsule and ligaments as well as by the starting position (i.e. more anterior laxity will be noted if the arm is examined in internal rotation - which relaxes the anterior structures, than if it is examined in external rotation - which tightens the anterior structures).
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Use the contralateral shoulder as an example of what is 'normal' for the patient.
1. Drawer Test
The patient is seated with the forearm resting on the lap and the shoulder relaxed. The examiner stands behind the patient. One of the examiner's hands stabilizes the shoulder girdle (scapula and clavicle) while the other grasps the proximal humerus. These tests are performed with (1) a minimal compressive load (just enough to center the head in the glenoid) and (2) with a substantial compressive load (to gain a feeling for the effectiveness of the glenoid concavity). Starting from the centered position with a minimal compressive load, the humerus is first pushed forward to determine the amount of anterior displacement relative to the scapula. The anterior translation of a normal shoulder reaches a firm end-point with no clunking, no pain and no apprehension. A clunk or snap on anterior subluxation or reduction may suggest a labral tear or Bankart lesion. The test is then repeated with a substantial compressive load applied before translation is attempted to gain an appreciation of the competency of the anterior glenoid lip. The humerus is returned to the neutral position and the posterior drawer test is performed, with light and again with substantial compressive loads to judge the amount of translation and the effectiveness of the posterior glenoid lip, respectively.(Silliman and Hawkins, 1993)
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