USF-LVHN SELECT
Biomechanical Evaluation of RSA Baseplate Designs: Implant Stability With and Without Glenoid Bone Loss.
Publication/Presentation Date
8-21-2025
Abstract
BACKGROUND: Baseplate fixation is a crucial step in reverse shoulder arthroplasty and presents a challenge when faced with deformities, or glenoid bone loss. Utilization of newer baseplates that are augmented to account for bone loss may provide equivalent stability to standard baseplates without bone loss. The purpose of this biomechanical study was to compare modern designs by evaluating three baseplates: (1) a one-piece monoblock design (RSP), (2) a two-piece non-locking baseplate (neutral) without bone loss and (3) a two-piece non-locking design with a wedge augment (wedge) with asymmetric bone loss.
METHODS: Polyurethane foam block cylinders (n=6 per group) with a density of 30 PCF were utilized. The six foam cylinders for the wedge baseplate were modified to stimulate 50% bone loss and the remaining 12 were left without modification, representing zero bone loss. Samples were mounted into a swing arm attached to the torque motor of a servo-electric test frame equipped with a 5kN load cell. Samples were cycled through a 55° (from neutral, ± 27.5°) arc of motion at 0.5 Hz for 10,000 cycles, while the test frame's actuator applied a constant 750 N compressive. Micromotion (μm) was measured throughout testing.
RESULTS: All samples survived 10,000 cycles of loading without catastrophic failure. None of the constructs exhibited micromotion above the 150 μm threshold. The baseplate micromotions at baseline were observed to be significantly different from one another (p=.001). After 10,000 cycles of loading, similar outcomes were observed where the Neutral had the lowest measured baseplate micromotion compared to RSP and the Wedge. The Wedge baseplate had significantly more micromotion compared to the RSP (p=.0167).
CONCLUSION: The neutral design was found to be the most stable, followed by the RSP and then the wedge design. All designs evaluated remained below the 150-micron threshold. The two-piece non-locking wedge baseplate design is a viable option for rTSA when dealing with bone loss.
LEVEL OF EVIDENCE: Basic Science Study; Biomechanics.
ISSN
1532-6500
Published In/Presented At
Diaz, M. A., Daniel, M., Sanchez-Urgelles, P., & Frankle, M. A. (2025). Biomechanical Evaluation of RSA Baseplate Designs: Implant Stability With and Without Glenoid Bone Loss. Journal of shoulder and elbow surgery, S1058-2746(25)00608-1. Advance online publication. https://doi.org/10.1016/j.jse.2025.07.009
Disciplines
Medical Education | Medicine and Health Sciences
PubMedID
40849060
Department(s)
USF-LVHN SELECT Program, USF-LVHN SELECT Program Students
Document Type
Article