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Title: A new alternative to expandable pedicle screws: Expandable poly-ether-ether-ketone shell
Authors: Demir, Teyfik
Keywords: Pedicle screw
expandable poly-ether-ether-ketone shell and fatigue
Issue Date: May-2015
Publisher: Sage Publications Ltd
Source: Demir, T. (2015). A new alternative to expandable pedicle screws: Expandable poly-ether-ether-ketone shell. Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 229(5), 386-394.
Abstract: Screw pullout is a very common problem in the fixation of sacrum with pedicle screws. The principal cause of this problem is that the cyclic micro motions in the fixation of sacrum are higher than the other regions of the vertebrae that limit the osteo-integration between bone and screw. In addition to that, the bone quality is very poor at sacrum region. This study investigated a possible solution to the pullout problem without the expandable screws' handicaps. Newly designed poly-ether-ether-ketone expandable shell and classical pedicle screws were biomechanically compared. Torsion test, pullout tests, fatigue tests, flexion/extension moment test, axial gripping capacity tests and torsional gripping capacity tests were conducted in accordance with ASTM F543, F1798 and F1717. Standard polyurethane foam and calf vertebrae were used as embedding medium for pullout tests. Classical pedicle screw pullout load on polyurethane foam was 564.8N compared to the failure load for calf vertebrae's 1264N. Under the same test conditions, expandable poly-ether-ether-ketone shell system's pullout loads from polyurethane foam and calf vertebrae were 1196.3 and 1890N, respectively. The pullout values for expandable poly-ether-ether-ketone shell were 33% and 53% higher than classical pedicle screw on polyurethane foam and calf vertebrae, respectively. The expandable poly-ether-ether-ketone shell exhibited endurance on its 90% of yield load. Contrary to poly-ether-ether-ketone shell, classical pedicle screw exhibited endurance on 70% of its yield load. Expandable poly-ether-ether-ketone shell exhibited much higher pullout performance than classical pedicle screw. Fatigue performance of expandable poly-ether-ether-ketone shell is also higher than classical pedicle screw due to damping the micro motion capacity of the poly-ether-ether-ketone. Expandable poly-ether-ether-ketone shell is a safe alternative to all other expandable pedicle screw systems on mechanical perspective.
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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