The failed fusion between two acromial apophyses, called an os acromiale, is often asymptomatic and found incidentally during evaluation for unrelated shoulder pathology. Though this is frequently not the primary pain source, a mobile os acromiale fragment can cause inflammation at the pseudarthrosis site, rotator cuff impingement, or AC joint arthritis. Varying operative techniques exist with good to satisfactory results for symptomatic patients. Several operative techniques have been described including open excision, open reduction-internal fixation (ORIF), arthroscopic acromioplasty or subacromial decompression, and arthroscopic excision. Open excision of a meso-acromion can lead to persistent pain and deltoid weakness and atrophy. The management of a meso-acromial fragment with ORIF can also result in persistent pain and deltoid weakness and atrophy with nonunion of the fragments. Arthroscopic excision of the meso-acromion is described as a viable alternative for surgical candidates.
Part of the book: Recent Advances in Arthroscopic Surgery