A Dual-Cup Reverse Shoulder Replacement Improves Impingement-Free Motion

• Published in: Seminars in arthroplasty 2025-01
• Main Authors: Alabsi, Rayan, Subramanya, Tejasvi, Livesey, Michael G., Kolakowski, Logan C., Badhyal, Subham, Aroom, Kevin, Zhang, Li-Qun, Wang, Martha O., Gilotra, Mohit N.
• Format: Article
• Language: English
• Subjects: biomechanics; cadaveric study; Reverse Shoulder arthroplasty; Shoulder; shoulder replacement
• ISSN: 1045-4527
• DOI: 10.1053/j.sart.2024.12.004

Advances in reverse shoulder arthroplasty (RSA) design have improved functional outcomes, which approach those of the anatomic total shoulder arthroplasty (aTSA) in certain patients. However, restoration of motion, especially functional internal rotation, remains a concern following RSA. A novel dual-cup RSA design1 was developed to improve impingement-free range of motion. The passive motion of the dual-cup RSA is compared to that of a commercially-available RSA design in a cadaveric model. Five fresh-frozen cadaveric upper extremity specimens were included in the study. The scapula was rigidly fixed, allowing for isolation of glenohumeral joint motion. The novel dual-cup RSA design was tested with and without a flanged component. The dual-cup has an outer diameter of 36 mm, articulates with a 32+4 mm glenosphere, and provides 6 mm of glenoid lateralization. A 32+4 mm lateralized glenosphere and a 36+6 mm lateralized glenosphere served as controls. Measurements of motion were performed using an electromagnetic tracking device and modes of impingement were recorded. An Analysis of Variance (ANOVA) test was performed with a post-hoc Tukey test to compare the relative changes in range of motion among groups. The dual-cup (without flange) design improved external rotation (ER) at 0° abduction by 20.9° and improved IR by 11.5° compared to the 32+4 mm control (p