The Influence of Postoperative Acromial and Scapular Spine Fractures on the Results of Reverse Shoulder Arthroplasty

Abstract

Fractures of the acromion or scapular spine are recognized complications of reverse arthroplasty. This study reviewed the outcome of reverse arthroplasties with such fractures and compared the results to arthroplasties without the fractures. A consecutive series of 125 reverse arthroplasties were reviewed for the development of a postoperative acromial or scapular spine fracture. Nine cases were identified, all treated nonoperatively. Five fractures occurred from falls, and the remainder were fatigue fractures. These results were compared to 67 patients with similar diagnoses in the series without such fractures. No significant differences existed between the 2 groups in terms of age, sex, side of surgery, or diagnosis. Preoperatively, both groups had substantial pain, limitation of motion, and poor American Shoulder and Elbow Surgeons (ASES) and Simple Shoulder Test (SST) outcome scores. No significant differences existed between the 2 groups. At minimum 1-year follow-up, results in the shoulders with fractures were improved. Mean visual analog score (VAS) was 4.0, flexion was 89.3 degrees, ASES score was 47.9, and SST score was 5.6. Nevertheless, these results were inferior to those in shoulders without a fracture, whose mean VAS was 0.7, flexion was 152.1 degrees, ASES score was 87.7, and SST score was 10.2. Nonoperative management was chosen in these cases due to a concern that stable fixation would not be obtained with surgery. Although the final outcome was diminished, these patients improved their preoperative state. A decision for surgical treatment will need to weigh the challenges of internal fixation with the incremental improvement that may occur with improved fracture healing.

Reverse shoulder arthroplasty

“…Despite deltoid induced acromial tilt in most patients, postoperative range of motion, Constant scores and subjective results were not diminished. In contrast, postoperative spine fractures (4 patients or 0.8% in this study), generally have poor results [65,66]. They often occur in the first year, and results of attempted internal fixation have been unsatisfactory.…”

Postoperative acromion base fracture resulting in subsequent instability of reverse shoulder replacement

“…Often considered to be insufficiency stress fractures, 14 many of these fractures develop after various degrees of trauma. 4,9 Fractures occur along several different areas of the acromion; however, those that are sustained at the acromion attachment to the scapular spine (acromion base) have been associated with the worst prognosis. 9 The position of the baseplate screws may also contribute to the development of acromion fractures.…”

“…4,9 Fractures occur along several different areas of the acromion; however, those that are sustained at the acromion attachment to the scapular spine (acromion base) have been associated with the worst prognosis. 9 The position of the baseplate screws may also contribute to the development of acromion fractures. Screws that are placed in the posterior-superior quadrant of the glenoid are typically directed toward the base of the acromion.…”

“…1,3,4,5,7,9,13,15,17 Although many acromion fractures heal uneventfully, worse outcomes have been reported for fractures that occur where the acromion base attaches to the scapular spine. 9,15 In these fractures, the entire acromion is pulled inferiorly, resulting in a change in the radiographic appearance of the shoulder. Because at least two-thirds of the deltoid origin is attached to the acromion and scapular spine, the inferior tilt of the acromion that occurs with these postoperative fractures can result in a loss of deltoid tension.…”

Management of complications after reverse shoulder arthroplasty

“…All acromial fractures were treated with conservative management and resulted in limitation in function. Hattrup et al [40] reported improved functional outcome results with conservative management of acromial and scapular spine fractures with greater of 1 year of follow-up. The authors cautioned against open reduction and internal fixation due to the challenges of stable internal fixation around this particular location.…”