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Factors Affecting the Stability of Reverse Shoulder Arthroplasty

Reverse shoulder arthroplasty is a relatively new procedure that is used to treat shoulders with massive rotator cuff tears combined with arthritis, a condition that is not well managed using conventional shoulder arthroplasty. By reversing the ‘ball-and-socket’ anatomy of the shoulder, the constraint of the joint can be increased. Despite the success of this prosthesis in improving pain and function, complication rates remain high and instability is often reported as the most commonly occurring complication. The mechanism of dislocation as well as factors that can be modified to decrease the risk of dislocation are not well understood for reverse shoulder arthroplasty. Therefore, the purpose of this study was to create a platform for examining the stability of reverse shoulder arthroplasty and use this to investigate factors affecting stability, including shoulder orientation (abduction and abduction plane angles), loading direction, glenosphere eccentricity and diameter, and humeral socket constraint.

An anatomical shoulder simulator was developed using a synthetic bone model and pneumatically actuated cables to represent the three heads of the deltoid. A displacing force was applied to the humeral head by a material testing machine in an anterior, posterior, superior, or inferior direction. The force required to dislocate the joint was used as a measure of stability and the identified factors and the interactions between factors were examined using a half-fraction factorial design experiment.

Increases in glenohumeral abduction or inferior-offset of the glenosphere were found to improve the stability of the prosthesis. Additionally, increased humeral socket depth resulted in greater stability for all loading directions, with the exception of inferior loading. Abduction plane angle and glenosphere diameter had no effect on the stability of reverse shoulder arthroplasty. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2011-12-23 11:42:21.592

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/6930
Date04 January 2012
CreatorsClouthier, Allison
ContributorsQueen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.))
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
LanguageEnglish, English
Detected LanguageEnglish
TypeThesis
RightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
RelationCanadian theses

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