JAAOS - 2026-06-23 - Journal Article
The Influence of Os Acromiale on Patient Outcomes After Reverse Total Shoulder Arthroplasty: A Matched Cohort Study.
Schneider BS, Pfaehler CD, Hao KA, Benjamin JA, Hones KM, Schoch BS, Wright JO, Wright TW, Farmer KW, LaMonica TJ, King JJ
Topics
Key Takeaway
Os acromiale (incidence 9.7%) does not adversely affect functional outcomes or complication rates after rTSA, with no significant differences in any ASES, SST, Constant, or ROM measure versus matched controls at minimum 2-year follow-up.
Summary Depth
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Summary
This study asked whether os acromiale negatively impacts outcomes after primary rTSA by comparing 64 shoulders with os acromiale to 320 1:5-matched controls from a prospective arthroplasty database. No statistically significant differences were found in any outcome score (ASES, SST, Constant, SPADI), shoulder strength, or active ROM at latest follow-up. Overall complication rates were similar (14% vs. 12%, P=0.658), and no outcome differences were detected between preacromion and meso-/meta-acromion subtypes.
Key Limitation
The study does not report whether os acromiale fragments were fixed, excised, or left alone intraoperatively, precluding any conclusion about optimal surgical management of the fragment.
Original Abstract
BACKGROUND
Although os acromiale is often noted on preoperative imaging in patients undergoing reverse total shoulder arthroplasty (rTSA), its clinical significance is ill-defined. The purpose of this study was to compare the clinical outcomes in shoulders with an os acromiale undergoing rTSA with a matched control group.
METHODS
We conducted a retrospective review of a prospectively collected shoulder arthroplasty database for patients who underwent primary rTSA with a minimum 2-year clinical follow-up. Preoperative imaging studies taken within 6 months of surgery were assessed for an os acromiale. Sixty-four shoulders with os acromiale were identified and were matched in a ratio of 1:5 to a control group (n = 320) based on age (within 3 years), sex (exact), preoperative diagnosis, preoperative forward elevation (within 5°) and American Shoulder and Elbow Surgeons score (within five points). Clinical outcome scores, shoulder strength, and active range of motion assessed preoperatively and at latest follow-up as well as the incidence of complications were compared between cohorts. Outcomes of meso- and meta-acromion were grouped and compared with preacromion shoulders.
RESULTS
The incidence of os acromiale was 9.7% (64/663) in our institution. Of these, 55% (n = 34) were preacromion, 38% (n = 24) were mesoacromion, and 8% (n = 5) were meta-acromion. No statistically significant differences were found in any outcome score, shoulder strength, or range of motion measures between shoulders with os acromiale and matched controls. Similar proportions of each cohort achieved a clinically significant benefit (minimal clinically important difference/substantial clinical benefit) for the Shoulder Pain and Disability Index, Simple Shoulder Test, American Shoulder and Elbow Surgeons score, constant score, abduction, forward flexion, external rotation, and internal rotation. Shoulders with os acromiale had a similar overall complication rate compared with matched controls (14% vs. 12%; P = 0.658). No statistical difference in outcomes were observed between the pre- and meso-/meta-acromion shoulders.
CONCLUSIONS
Patients with os acromiale undergoing rTSA have similar postoperative functional outcomes and pain relief compared with matched controls.
LEVEL OF EVIDENCE
Ⅲ, Retrospective Matched Cohort Study.