A parametric study of cylindrical pedicle screw design implications on the pullout performance using an experimentally validated finite-element model

Chatzistergos, PE; Magnissalis, EA; Kourkoulis, SK

dc.contributor.author	Chatzistergos, PE	en
dc.contributor.author	Magnissalis, EA	en
dc.contributor.author	Kourkoulis, SK	en
dc.date.accessioned	2014-03-01T01:32:29Z
dc.date.available	2014-03-01T01:32:29Z
dc.date.issued	2010	en
dc.identifier.issn	1350-4533	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/20163
dc.subject	Bone screws	en
dc.subject	Pullout force	en
dc.subject	Finite element analysis	en
dc.subject	Cohesive zone	en
dc.subject	Synthetic bone	en
dc.subject.classification	Engineering, Biomedical	en
dc.subject.other	CANCELLOUS BONE SCREWS	en
dc.subject.other	HOLDING POWER	en
dc.subject.other	OUT STRENGTH	en
dc.subject.other	BIOMECHANICAL TESTS	en
dc.subject.other	ORTHOPEDIC SCREWS	en
dc.subject.other	THREAD DESIGN	en
dc.subject.other	HUMAN SPINE	en
dc.subject.other	FIXATION	en
dc.subject.other	COMPLICATIONS	en
dc.subject.other	REPLACEMENT	en
dc.title	A parametric study of cylindrical pedicle screw design implications on the pullout performance using an experimentally validated finite-element model	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.medengphy.2009.11.003	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.medengphy.2009.11.003	en
heal.language	English	en
heal.publicationDate	2010	en
heal.abstract	The present study aims to the design of a finite-element model simulating accurately the pullout behaviour of cylindrical pedicle screws and predicting their pullout force. Three commercial pedicle screws, subjected to pure pullout from synthetic bone, were studied experimentally. The results were used for the design, calibration and validation of a finite-element model. Special attention was paid to the accurate simulation of the failure inside the host material under shear. For this purpose, a bilinear cohesive zone material model was adopted, controlling the mode-II debonding of neighbouring elements in the vicinity of the screw. Comparison between experimental and numerical results proved that the implementation of this approach can significantly enhance the accuracy of the numerical simulation of a screw's mechanical behaviour under pure pullout loads. The numerical model was used for the parametric study of various factors affecting the pullout performance of a cylindrical pedicle screw. It was concluded that the major parameter influencing the pullout force is the outer radius (increasing its value by 36% increases the pullout force by 34%). The influence of the purchase length of the screw is of similar quantitative nature. The respective dependence on the thread inclination, depth and pitch was significantly weaker. (C) 2009 IPEM. Published by Elsevier Ltd. All rights reserved.	en
heal.publisher	ELSEVIER SCI LTD	en
heal.journalName	MEDICAL ENGINEERING & PHYSICS	en
dc.identifier.doi	10.1016/j.medengphy.2009.11.003	en
dc.identifier.isi	ISI:000276189800006	en
dc.identifier.volume	32	en
dc.identifier.issue	2	en
dc.identifier.spage	145	en
dc.identifier.epage	154	en