Impact of scapular notching on glenoid fixation in reverse total shoulder arthroplasty:an in vitro and finite element study

Abstract

Background: The high incidence of scapular notching in reverse total shoulder arthroplasty (RTSA) has spurred several methods to minimize bone loss. However, up to 93% of RTSAs accompanying scapular notching have been reported to maintain good implant stability for over 10 years. This study was conducted to investigate the relationship between scapular notching and glenoid fixation in RTSA. Methods: Cadaveric testing was performed to measure the notch-induced variations in strain on the scapular surface and micromotion at the bone-prosthesis interface during arm abductions of 30°, 60°, and 90°. Finite element analysis was used to further study the bone and screw stresses as well as the bone-prosthesis micromotion in cases with a grade 4 notch during complicated arm motions. Results: The notch resulted in an apparent increase in inferior screw stress in the root of the screw cap and at the notch-screw conjunction. However, the maximum stress (172 MPa) along the screw after notching is still much less than the fatigue strength of the titanium screw (600 MPa) under cyclic loading. The bone-prosthesis micromotion results did not present significant notch-induced variations. Conclusions: Scapular notching will lead to few impacts on the stability of an RTSA on the glenoid side. This finding may explain the long-term longevity of RTSA in cases of severe scapular notching. The relationship between scapular notching and weak regions along the inferior screw may explain why fractures of the inferior screw are sometimes reported in patients with RTSA clinically.

Publication DOI: https://doi.org/10.1016/j.jse.2020.01.087
Divisions: College of Engineering & Physical Sciences > School of Engineering and Technology > Mechanical, Biomedical & Design
Additional Information: © 2020, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Uncontrolled Keywords: Basic Science Study,Biomechanics and Computer Modeling,finite element analysis,fixation,in vitro testing,micromotion,reverse total shoulder arthroplasty,Scapular notching,Surgery,Orthopedics and Sports Medicine
Publication ISSN: 1532-6500
Last Modified: 18 Jun 2024 07:27
Date Deposited: 15 Jun 2020 08:10
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
https://www.sci ... 05827462030152X (Publisher URL)
PURE Output Type: Article
Published Date: 2020-10
Published Online Date: 2020-05-12
Accepted Date: 2020-05-01
Authors: Zhang, Min
Junaid, Sarah (ORCID Profile 0000-0001-9460-710X)
Gregory, Thomas
Hansen, Ulrich
Cheng, Cheng Kung

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