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- Ghandour, Salim, et al.
(författare)
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A model for the biomechanical assessment of discoplasty in a laboratory setting
- 2021
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Percutaneous cement discoplasty is a spinal surgical technique which has been rarely tested outside the clinical setting. This study aimed at developing an ovine model framework to allow testing and optimization of discoplasty in a lab-controlled environment.
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| 2. |
- Ghandour, Salim, et al.
(författare)
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An ex-vivo Biomechanical Assessment of Cement Discoplasty
- 2021
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Spinal fusion is the golden standard for treating degenerative disc disease. However, elderly patients with underlying chronic conditions cannot undergo spinal fusion due to healing impairment, risks of infection, and/or even morbidity. Percutaneous Cement Discoplasty (PCD) is a relatively new procedure that involves injecting poly(methyl methacrylate) (PMMA) cement into the disc to reduce pain and attempt to maintain spinal curvature and height. Therefore, this minimally invasive method could be an advantageous option for patients for whom open surgery is deemed too risky [1]. While this technique has already been attempted clinically, to the authors knowledge, only one preliminary study on the biomechanics of PCD is currently available [2]. This study aims to develop a more clinically relevant and repeatable method to study PCD in a lab setting. To this end, ovine spine was tested in three different categories: healthy disc; injured disc; treated disc. A papain enzyme solution [3] was used to create the vacuum phenomena in the sheep spine to represent the injury as observed in a clinical setting. Preliminary compression testing showed promising results with a significant increase in stability of the segments after treatment. Further on, this testing method can be used to test different materials, surgical methods and biomechanical behaviour to further advance PCD.
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| 3. |
- Grzeszczak, Ana, 1995-, et al.
(författare)
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Mechanical and Structural Evaluation of Synthetic Trabecular Bone Models Printed with Stereolithography
- 2021
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Ingår i: Mechanical and Structural Evaluation of Synthetic Trabecular Bone Models Printed with Stereolithography.
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Konferensbidrag (refereegranskat)abstract
- Mechanical and Structural Evaluation of Synthetic Trabecular Bone Models Printed with StereolithographyA. Grzeszczak1, S. Lewin1, O. Eriksson2, J. Kreuger2, C. Persson11Department of Materials Science and Engineering, Uppsala University, Uppsala, Sweden2Department of Medical Cell Biology, Uppsala University, Uppsala, SwedenINTRODUCTION: Synthetic bone models are needed to train surgeons but also to test and design medical equipment. However, currently available models do not accurately mimic the complex structure of trabecular bone [1]. This study aimed to investigate the suitability of stereolithography (SLA) printing to produce synthetic trabecular bone models.METHODS: The synthetic bone models were printed by SLA using a CAD-model generated from micro-computed tomography (micro-CT) synchrotron images of human trabecular bone [2]. To adjust the printing parameters, the influence of the following variables on the mechanical properties was investigated: printer type, orientation, resolution and UV-curing time. Subsequently, the trabecular CAD-model was printed at the original scale (scale factor 1), and with several enlarging factors. Mechanical properties were evaluated by compression and screw pullout tests, and structure replicability was assessed with micro-CT.RESULTS & DISCUSSION: The elastic modulus of the control group was not statistically different from that of the other batches after the printing parameters configuration, standard parameters were therefore used. The orientation of the samples on the build platform of the printer did not seem to have an influence on the ratio Bone Volume/Total Volume for trabecular samples. For the bone models with scaling factors below 1.8, micro-CT image analysis showed major artefacts due to printing and a low accuracy in trabecular thickness distribution. Analysis of the total printed volume showed a difference to the original model higher than 50% for scale 1.5 and lower than 10% for scales 1.8 and above (Fig. 1). A refined overlap comparison with the original bone model showed that the scale 1.8 exhibited errors higher than 20%, implying printing inaccuracies of the smaller details. The pullout strength obtained for SLA-printed parts was higher than for existing synthetic models (Sawbones™) and cadaveric specimens, but within the same range as FDM-printed parts in poly(lactic acid) [2].CONCLUSIONS: Trabecular bone models with a scale factor of 1.8 or greater could be produced with acceptable accuracy, but models with smaller scale factors were not well printed. Nevertheless, for the same 3D model, a higher resolution was reached by SLA as compared to FDM [2].ACKNOWLEDGEMENTS: The authors are grateful to Adam Engberg at U-PRINT: Uppsala University’s 3D-printing facility at the Disciplinary Domain of Medicine and Pharmacy for support and advice on the printers. This research was funded by Sweden’s Innovation Agency VINNOVA, grant number 2019-00029.REFERENCES: [1] M. Poukalova et al., “Pullout strength of suture anchors: Effect of mechanical properties of trabecular bone,” J. Biomech., vol. 43, no. 6, pp. 1138–1145, Apr. 2010, doi: 10.1016/j.jbiomech.2009.12.007. [2] D. Wu, A. Spanou, A. Diez-Escudero, and C. Persson, “3D-printed PLA/HA composite structures as synthetic trabecular bone: A feasibility study using fused deposition modeling,” J. Mech. Behav. Biomed. Mater., vol. 103, p. 103608, Mar. 2020, doi: 10.1016/j.jmbbm.2019.103608.
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| 4. |
- Grzeszczak, Ana, 1995-, et al.
(författare)
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Stereolithography shows potential in additive manufacturing ofsynthetic trabecular bone structures
- 2021
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Ingår i: Stereolithography shows potential in additive manufacturing ofsynthetic trabecular bone structures.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Title and AuthorsTitle: Stereolithography shows potential in additive manufacturing of synthetic trabecular bone structures.Authors: Ana Grzeszczak, Susanne Lewin, Olle Eriksson, Johan Kreuger, Cecilia Persson IntroductionSynthetic bone models are needed to train surgeons but also to test and design medical devices such as screws for fracture fixation. However, currently available models do not accurately mimic the trabecular bone and its complex structure [1]. This study aimed to investigate if stereolithography (SLA) additive manufacturing could produce synthetic trabecular bone models with high accuracy. Experimental methods The synthetic bone models were printed by SLA (Formlabs Black resin, Form3 printer). The CAD-model had been generated from micro-computed tomography (micro-CT) synchrotron images of human trabecular bone [2]. The model was printed at the original scale (scale factor 1), and with upscaling factors up to 4.3. Structure replicability was assessed with micro-CT, and the mechanical properties were evaluated by compression and screw pullout tests. Dense cylinders of the printed material were also tested in compression for material characterization.Results and discussionThe elastic moduli obtained by compression of dense cylinders were approximately ten times lower than average values for human cortical bone. For the trabecular bone models with scaling factors below 1.8, micro-CT image analysis showed major artefacts due to printing and a low accuracy in trabecular thickness distribution. Analysis of the total printed volume showed a difference to the original model higher than 50% for scale 1.5 (Fig. 1). However, this difference was less than 10% for scales 1.8 and above, although a refined overlap comparison with the original bone model showed that the scale 1.8 exhibited errors higher than 20%, implying printing inaccuracies of the smaller details. The pullout strength of SLA-printed parts was higher than for existing synthetic models (Sawbones™) and cadaveric specimens, but within the same range as FDM-printed parts in poly(lactic acid) [2].ConclusionIn conclusion, trabecular bone models with a scale factor of 1.8 or larger could be printed with acceptable accuracy, but models with smaller scale factors were not well represented. However, for the same 3D model, a higher resolution was achieved by SLA as compared to FDM [2]. AcknowledgementsThe authors are grateful to Adam Engberg at U-PRINT: Uppsala University’s 3D-printing facility at the Disciplinary Domain of Medicine and Pharmacy for support and advice on the printers. This research was funded by Sweden’s Innovation Agency VINNOVA, grant number 2019-00029.References[1] M. Poukalova et al., “Pullout strength of suture anchors: Effect of mechanical properties of trabecular bone,” J. Biomech., vol. 43, no. 6, pp. 1138–1145, Apr. 2010, doi: 10.1016/j.jbiomech.2009.12.007.[2] D. Wu, A. Spanou, A. Diez-Escudero, and C. Persson, “3D-printed PLA/HA composite structures as synthetic trabecular bone: A feasibility study using fused deposition modeling,” J. Mech. Behav. Biomed. Mater., vol. 103, p. 103608, Mar. 2020, doi: 10.1016/j.jmbbm.2019.103608.
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