Arthroscopic excision of os acromiale: effects on deltoid function and strength.

Arthroscopic excision of os acromiale is a feasible alternative to open excision or fusion. This article describes the authors' experience with 28 patients (31 shoulders) who underwent arthroscopic excision of os acromiale and its effect on shoulder pain and function, with specific emphasis on deltoid strength measurement. Thirty-one os acromiale (all persistent unfused pre- and meso-acromions) in 28 patients were excised arthroscopically. Sixteen patients underwent concomitant rotator cuff repair (9 arthroscopic and 7 mini-open). At an average follow-up of 41 months, the patients were assessed using the American Shoulder and Elbow Surgeons (ASES) score, and deltoid function and strength were measured. Pain was completely alleviated postoperatively in 20 (65%) shoulders, and 9 (29%) shoulders had less pain postoperatively. Pain worsened postoperatively in 2 patients, both of whom had features of glenohumeral arthritis at arthroscopy. Average postoperative ASES score (80.33) was significantly improved compared with the average preoperative score (33.71). No significant loss of deltoid strength occurred compared with the contralateral side. No objective or subjective loss of normal deltoid appearance occurred. Rotator cuff repair did not compromise deltoid strength or significantly reduce ASES score irrespective of repair technique (arthroscopic vs mini-open). With careful attention to surgical technique maintaining an intact periosteal sleeve to preserve the integrity of the deltoid attachment, arthroscopic excision is an effective management tool for mobile os acromiale in a painful shoulder requiring surgical intervention.