The Subacromial Balloon Spacer Versus Superior Capsular Reconstruction in the Treatment of Irreparable Rotator Cuff Tears: A Biomechanical Assessment
Arthroscopy - Journal of Arthroscopic and Related Surgery
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© 2019 Arthroscopy Association of North America Purpose: To compare the subacromial balloon spacer with superior capsular reconstruction (SCR) for the treatment of massive irreparable rotator cuff tears. Methods: Eight male cadaveric shoulders were mounted on a custom shoulder simulator that permitted quasistatic deltoid and rotator cuff muscle loading. Four shoulder conditions were tested: intact, irreparable rotator cuff tear (torn), subacromial balloon spacer, and SCR. The primary outcomes were superior humeral head migration and functional shoulder abduction force, which were measured at 0°, 30°, 60°, and 90° of shoulder abduction. Results: In comparison to the intact condition, the torn condition resulted in a significant increase in superior humeral head migration at 0° (P =.03) and 30° (P =.02) of abduction. Insertion of the subacromial balloon spacer restored the humeral head position such that it was not significantly different from the intact condition (P =.18). Similarly, SCR restored the humeral head position such that it was not significantly different from the intact condition (P =.99). No significant differences were found between the balloon and SCR (P =.99). The functional abduction force was significantly decreased after tear creation (P =.01); however, the subacromial balloon (P =.40) and SCR (P =.99) restored functional abduction force comparable to the intact shoulder state. Conclusions: On the basis of the results, both techniques function to decrease superior humeral head migration and to restore more normal glenohumeral joint position and forces during various abduction positions. No substantial differences were identified between techniques at time zero. Clinical Relevance: The results of this laboratory study indicate that the balloon and SCR both provided mechanical effects that restored the humeral head position from the superiorly migrated location. As such, similar clinical effects can be expected at time zero in patients with massive rotator cuff tears.