Os Acromiale Rupture Associated with a Massive Rotator Cuff Tear Causing Deltoid Insufficiency and Superior Escape of the Humeral Head: A Case Report.

Abstract

Os acromiale is an anatomic variant that occurs in approximately 8% of the population1,2. It represents a failure of fusion of the anterior acromial apophysis. Often, it is an incidental radiographic finding in the evaluation of a patient with shoulder pain. The incidence of symptoms caused by an os acromiale is unknown, but there is a well-documented association with impingement syndromes and rotator cuff tears3. Surgical management is indicated for failure of nonoperative treatment or for full-thickness rotator cuff tears. Deltoid insufficiency associated with rotator cuff tears without prior surgical intervention is quite rare, with only a small number of cases reported in the literature4. After a thorough literature search, we believe that this is the first case report that describes an unstable os acromiale with a massive rotator cuff tear that caused deltoid insufficiency with superior escape of the humeral head. The patient was informed that data concerning the case would be submitted for publication, and he provided consent. A forty-six-year-old, right-hand-dominant, healthy man initially presented to the referring physician for right shoulder pain and dysfunction. He reported that he had been experiencing right shoulder pain for approximately two years. Physical examination revealed forward flexion to 155° bilaterally, external rotation of 35° bilaterally, and internal rotation to the midlumbar spine bilaterally. He had 4+/5 strength on supraspinatus and infraspinatus testing. He had a positive Neer sign with positive Hawkins signs bilaterally. Radiographs revealed a high-riding humeral head with the presence of a meso-os acromiale (Figs. 1-A and 1-B). He was diagnosed with a chronic full-thickness rotator cuff tear. He was treated nonoperatively with several subacromial corticosteroid injections, physical therapy, and nonsteroidal anti-inflammatory medication. The pain subsided, and he did well for approximately ten months. Anteroposterior (Fig. 1-A) and lateral (Fig. 1-B) radiographs of the right shoulder reveal a high-riding humeral head and a meso-os acromiale with subtle displacement (arrows). Fig. 1-A Fig. 1-B The patient continued to do well until …