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Title: Investigation of toggling effect on pullout performance of pedicle screws
Authors: Aycan, Mehmet Fatih
Yaman, Mesut Emre
Usta, Yusuf
Demir, Teyfik
Tolunay, Tolga
Demir, Teyfik [144123]
Keywords: expandable polyetheretherketone shell
pullout strength
bovine vertebra
pedicle screw
polyurethane foam
Issue Date: 1-Apr-2018
Publisher: SAGE Publications Ltd
Source: Aycan, M. F., Yaman, M. E., Usta, Y., Demir, T., & Tolunay, T. (2018). Investigation of toggling effect on pullout performance of pedicle screws. Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 232(4), 395-402.
Abstract: Objective of this study is to assess the pullout performance of various pedicle screws in different test materials after toggling tests comparatively. Solid core, cannulated (cemented), novel expandable and solid-core (cemented) pedicle screws were instrumented to the polyurethane foams (Grade 10 and Grade 40) produced in laboratory and bovine vertebra. ASTM F543 standard was used for preparation process of samples. Toggling tests were carried out. After toggling test procedures, pullout tests were performed. Load versus displacement graph was recorded, and the ultimate pullout force was defined as the maximum load (pullout strength) sustained before failure of screw. Anteriosuperior and oblique radiographs were taken from each sample after instrumentation in order to examine screw placement and cement distribution. The pullout strength of pedicle screws decreased after toggling tests with respect to the initial condition. While the cemented solid-core pedicle screws had the highest pullout strength in all test materials, they had the highest strength differences. The cemented solid-core pedicle screws had decrement rates of 27% and 16% in Grade 10 and Grade 40, respectively. There are almost same decrement rate (between 5.5% and 6.5%) for all types of pedicle screws instrumented to the samples of bovine vertebra. The pullout strengths of novel expandable pedicle screws in both of early period and after toggling conditions were almost similar, in other words, the decrement rates of it were lower than other types. According to the data collected from this study, polymethylmethacrylate augmentation significantly decreases pullout strength following the toggling loads. Higher brittleness of cured polymethylmethacrylate has adverse effect on the pullout strength. Although augmentation is an important process for enhancing pullout strength in early period, it has some disadvantages for preserving stabilization in a long time. Expandable pedicle screw with polyetheretherketone shell may be good alternative to polymethylmethacrylate augmentation on both primer stabilization and long-term loading application with toggling.
ISSN: 0954-4119
Appears in Collections:Makine Mühendisliği Bölümü / Department of Mechanical Engineering
PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collection
Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

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