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Mechanical and in vivo assessment of injectable germanium based glass ionomer cements for vertebroplasty

2016; Frontiers Media; Volume: 4; Linguagem: Inglês

10.3389/conf.fbioe.2016.01.02450

2296-4185

Dickey Brett, Lauren Kiri, Pierlot Caitlin, B. Daniel,

Facial Trauma and Fracture Management

Event Abstract Back to Event Mechanical and in vivo assessment of injectable germanium based glass ionomer cements for vertebroplasty Brett Dickey1, Lauren Kiri2, Caitlin Pierlot2 and Daniel Boyd1, 2 1 Dalhousie University, School of Biomedical Engineering, Canada 2 Dalhousie University, Department of Applied Oral Sciences, Canada Introduction: Vertebroplasty (VP) is a minimally invasive procedure where bone cement is injected into vertebral fractures for palliative relief via fracture stabilization. Basic requirements of VP cements include 5-20 min of injection time and lasting compression strength (σc) >30 MPa [1],[2]. Germanium containing glass ionomer cements (Ge-GICs) demonstrate appropriate handling characteristics for VP [3], but weaken significantly over time and little is known regarding their in vivo performance. The objectives of this study were to: (i) establish composition-property relationships to mitigate the known mechanical decline of Ge based GICs; (ii) quantify their potential as injectable cements; and (iii) conduct a pilot animal trial to gain preliminary biocompatibility data. Materials and Methods: Design of mixtures (DOM) was used to identify 12 glass compositions. Glasses were synthesized via a melt-quench technique, ground to ≤45 µm, and annealed (Tg – 30˚C). GICs were prepared by mixing glass powders with polyacrylic acid (Mw=12,700 g/mol, 50 wt% aq. sol.) at a 4:3 ratio. GIC σc was evaluated up to 180 days and DOM response models were produced for relevant time points. An additional composition (DG302) was interpolated from within the design space and synthesized to validate the DOM models. Injectability of DG302 GIC was assessed by profiling the force required to extrude cement from a 1 cc syringe with a 12 G cannula over time. AccelLAB (Boisbriand, CAN) was contracted for the in vivo pilot, where DG302 filled 4 subcritical femoral defects in 2 male NZ white rabbits with a sham control over an 8-week period (e.g. Fig. 1). Post-sacrifice, defects were scanned using MicroCT to reconstruct 3-D images of the implants, then sectioned, stained with Goldner’s Trichrome, and graded according to cell type and local host response. Systemic effects of the DG302 implants were also assessed via blood work. Results and Discussions: Ge-GIC mechanical performances were successfully improved, e.g. σc of DG302 increased from 51 MPa at 1 day to 71 MPa at 180 days. DOM models identified ZrO2/Na2O content as the most influential factor on σc, and SiO2:GeO2 ratio key to ensure long-term mechanical stability. DG302 injection profiles exhibited an initial injection force of 16 N that increased to 62 N after 15 min. All animals maintained healthy weights and appetites, and concerns regarding the long-term stability of Ge-GICs were further mitigated as DG302 implants remained intact over the 8 weeks studyA. Conclusion: Precise manipulation of glass chemistry yields Ge-GICs with clinically viable handling and mechanical properties that are stable in vivo. These characteristics exemplify a practical foundation to further the investigation of Ge-GICs for minimally invasive procedures such as VP. A. Full histopathological and hematological results to be obtained in October 2015 and not available at the time of abstract submission, but will be included in presentation of this work at WBC. Figure 1: MicroCT section of DG302 implant (identified by black arrow) in rabbit femoral defect model after 8 weeks. References:[1] Heini and Berlemann, 2001 Eur Spine J 10, s205-s213[2] Jansen et al. 2005, Orthop Clin N Am 36[3] Dickey et al. 2013 JMBBM 23 Keywords: biomaterial, Biocompatibility, mechanical property, Novel material Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Biomaterials in musculoskeletal orthopeadics and tissues Citation: Dickey B, Kiri L, Pierlot C and Boyd D (2016). Mechanical and in vivo assessment of injectable germanium based glass ionomer cements for vertebroplasty. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.02450 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. 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