The effect of the subacromial balloon spacer on humeral head translation in the treatment of massive, irreparable rotator cuff tears: a biomechanical assessment
Journal of Shoulder and Elbow Surgery
URL with Digital Object Identifier
© 2019 Journal of Shoulder and Elbow Surgery Board of Trustees Background: The current management of massive, irreparable rotator cuff tears is challenging, and no individual surgical technique has demonstrated clinical superiority. This study evaluated the role of a subacromial balloon spacer and its ability to depress the humeral head in the setting of a massive, irreparable rotator cuff tear. Methods: Eight cadaveric shoulders were tested. The specimens were mounted onto a shoulder simulator that applied muscle loading. Five shoulder states were tested: intact; irreparable rotator cuff tear; and inflation of the subacromial balloon spacer with 10, 25, and 40 mL of saline solution on the irreparable rotator cuff tear. Humeral head migration was measured at 0°, 30°, 60°, and 90° of shoulder abduction. Results: After creation of a massive, irreparable rotator cuff tear, in 0° of abduction, the humeral head migrated superiorly by a mean of 3.5 ± 0.7 mm compared with the intact shoulder state (P = .002). The subacromial balloon spacer inflated to 25 mL translated the humeral head inferiorly relative to the torn state by an average of 3.2 ± 0.6 mm (P = .001) for all abduction angles. The balloon inflated to 10 mL was ineffective at restoring humeral head position as it was still significantly superior than intact (P = .017). The balloon inflated to 40 mL was successful in depressing the humeral head; however, it over-translated the humeral head anteroinferiorly, such that it was significantly different from the intact condition (P < .001). Overall, the 25-mL balloon best restored the humeral head position. Conclusion: The results of this study demonstrate that the subacromial balloon spacer is most effective in depressing the humeral head and restoring the glenohumeral joint position when inflated to 25 mL.