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- Engstrand, Johanna, et al.
(författare)
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Influence of polymer addition on the mechanical properties of a premixed calcium phosphate cement
- 2013
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Ingår i: Biomatter. - : Informa UK Limited. - 2159-2535. ; 3:4, s. e27249-
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Tidskriftsartikel (refereegranskat)abstract
- Premixed calcium phosphate cements can reduce handling complications that are associated with the mixing of cements in the operating room. However, to extend the clinical indication of ceramic cements their mechanical properties need to be further improved. The incorporation of a polymeric material with intrinsically high tensile properties could possibly assist in increasing the mechanical properties of calcium phosphate cement. In this study polymer microparticles made from poly(lactid-co-glycolide) plasticised with poly(ethylene glycol) 400 (PLGA/PEG microparticles) were added in amounts of up to 5 wt% to a premixed acidic calcium phosphate cement. The PLGA/PEG microparticles added undergo a shape transformation at 37°C, which could give a better integration between polymer microparticles and ceramic cement compared to polymer microparticles lacking this property. The results showed that the incorporation of 1.25 wt% PLGA/PEG microparticles increased the compressive strength by approximately 20% up to 15.1 MPa while the diametral tensile strength was kept constant. The incorporation of PLGA/PEG microparticles increased the brushite to monetite ratio after setting compared to pure ceramic cements. In conclusion, small amounts of PLGA/PEG microparticles can be incorporated into premixed acidic calcium phosphate cement and increase their mechanical properties, which could lead to increased future applications.
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| 4. |
- Lewin, Susanne, et al.
(författare)
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Monetite-based composite cranial implants demonstrate long-term clinical volumetric balance by concomitant bone formation and degradation
- 2021
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Ingår i: Acta Biomaterialia. - : Elsevier. - 1742-7061 .- 1878-7568. ; 128, s. 502-513
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Tidskriftsartikel (refereegranskat)abstract
- The use of calcium phosphates (CaPs) as synthetic bone substitutes should ideally result in a volumetric balance with concomitant bone formation and degradation. Clinical data on such properties is nevertheless lacking, especially for monetite-based CaPs. However, a monetite-based composite implant has recently shown promising cranial reconstructions, with both CaP degradation and bone formation. In this study, the volumetric change at the implant site was quantified longitudinally by clinical computed tomography (CT). The retrospective CT datasets had been acquired postoperatively ( n = 10), in 1-year ( n = 9) and 3-year ( n = 5) follow-ups. In the 1-year follow-up, the total volumetric change at the implant site was-8 +/- 8%. A volumetric increase (bone formation) was found in the implant-bone interface, and a volumetric decrease was observed in the central region (CaP degradation). In the subjects with 2-or 3-year follow-ups, the rate of volumetric decrease slowed down or plateaued. The reported degradation rate is lower than previous clinical studies on monetite, likely due to the presence of pyrophosphate in the monetite-based CaP-formulation. A 31-months retrieval specimen analysis demonstrated that parts of the CaP had been remodeled into bone. The CaP phase composition remained stable, with 6% transformation into hydroxyapatite. In conclusion, this study demonstrates successful bone-bonding between the CaP-material and the recipient bone, as well as a long-term volumetric balance in cranial defects repaired with the monetitebased composite implant, which motivates further clinical use. The developed methods could be used in future studies for correlating spatiotemporal information regarding bone regeneration and CaP degradation to e.g. patient demographics. Statement of significance In bone defect reconstructions, the use of calcium phosphate (CaP) bioceramics ideally results in a volumetric balance between bone formation and CaP degradation. Clinical data on the volumetric balance is nevertheless lacking, especially for monetite-based CaPs. Here, this concept is investigated for a composite cranial implant. The implant volumes were quantified from clinical CT-data: postoperatively, one year and three years postoperatively. In total,-8 +/- 8% ( n = 9) volumetric change was observed after one year. But the change plateaued, with only 2% additional decrease at the 3-year follow-up ( n = 5), indicating a lower CaP degradation rate. Osseointegration was seen at the bone-implant interface, with a 9 +/- 7% volumetric change after one year. This study presented the first quantitative spatiotemporal CT analysis of monetite-based CaPs.
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- Wu, Dan, 1990-, et al.
(författare)
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Young’s modulus of trabecular bone at the tissue level : A review
- 2018
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Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1742-7061 .- 1878-7568. ; 78, s. 1-12
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Forskningsöversikt (refereegranskat)abstract
- The tissue-level Young’s modulus of trabecular bone is important for detailed mechanical analysis of bone and bone-implant mechanical interactions. However, the heterogeneity and small size of the trabecular struts complicate an accurate determination. Methods such as micro-mechanical testing of single trabeculae, ultrasonic testing, and nanoindentation have been used to estimate the trabecular Young’s modulus. This review summarizes and classifies the trabecular Young’s moduli reported in the literature. Information on species, anatomic site, and test condition of the samples has also been gathered. Advantages and disadvantages of the different methods together with recent developments are discussed, followed by some suggestions for potential improvement, for future work. In summary, this review provides a thorough introduction to the approaches used for determining trabecular Young’s modulus, highlights important considerations when applying these methods and summarizes the reported Young’s modulus for follow-up studies on trabecular properties.
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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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| 8. |
- 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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