Arthroscopic decompression of shoulder impingement secondary to Os acromiale.

Os acromiale is the result of failure of one of the outer ossification centers of the acromion to unite with the more medial portion. This creates an additional motion segment which may itself contribute to impingement syndrome of the shoulder or which may create hypertrophy or spurs which directly impinge on the cuff. Three cases of impingement syndrome of the shoulder with associated os acromiale are presented. All three were initially relieved with arthroscopic subacromial decompression of either the entire os acromiale or simply of the impinging spur. After 1 year, however, all three had recurrent or continued complaints of pain and/or impingement. Therefore, it would appear that arthroscopic subacromial decompression is not a solution to impingement syndrome secondary to os acromiale. Careful preoperative radiographic evaluation to rule out all causes of impingement syndrome including os acromiale is essential so that the surgeon may better choose an approach to decompression.