Examination under anesthesia for evaluation of anterior shoulder instability

Thirty patients with unilateral, traumatic recurrent anterior instability w ere assessed by examination under anesthesia of both shoulders in the anter ior, anteroinferior, inferior, posterior, and posteroinferior directions wh ile the examiner controlled the patients' arm rotation, There were signific ant side-to-side differences in humeral head translation, depending on arm rotation, Humeral head translation was significantly greater in the abnorma l shoulder only in the anteroinferior direction with 40 degrees and 80 degr ees of external rotation of the arm. Defining an "abnormal" examination as grade 3 translation (translation of the humeral head up onto the glenoid ri m) or grade 4 translation (translation of the humeral head over the glenoid rim, that is, dislocated) and translation two grades greater than the cont ralateral uninjured side, the test sensitivity was 83%, and the test specif icity was 100%, Assessing humeral head translation by examination under ane sthesia is a useful adjunct to the diagnostic tools for shoulder instabilit y, but the number of tests should be expanded to include the anteroinferior and posteroinferior directions, and the tests should be done with the arm in varying degrees of rotation.