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  • 1.
    Bou-Francis, Antony
    et al.
    School of Mechanical Engineering, University of Leeds, UK.
    Lopez, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hall, Richard M.
    School of Mechanical Engineering, University of Leeds, UK.
    Kapur, Nikil
    School of Mechanical Engineering, University of Leeds, UK.
    Assessing cement injection behaviour in cancellous bone: An in vitro study using flow models2014In: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 29, no 4, p. 582-594Article in journal (Refereed)
    Abstract [en]

    Understanding the cement injection behaviour during vertebroplasty and accurately predicting the cement placement within the vertebral body is extremely challenging. As there is no standardized methodology, we propose a novel method using reproducible and pathologically representative flow models to study the influence of cement properties on injection behaviour. The models, confined between an upper glass window and a lower aluminium plate, were filled with bone marrow substitute and then injected (4, 6 and 8min after cement mixing) with commercially available bone cements (SimplexP, Opacity+, OsteopalV and Parallax) at a constant flow rate (3mL/min). A load cell was used to measure the force applied on the syringe plunger and calculate the peak pressure. A camera was used to monitor the cement flow during injection and calculate the following parameters when the cement had reached the boundary of the models: the time to reach the boundary, the filled area and the roundness. The peak pressure was comparable to that reported during clinical vertebroplasty and showed a similar increase with injection time. The study highlighted the influence of cement formulations and model structure on the injection behaviour and showed that cements with similar composition/particle size had similar flow behaviour, while the introduction of defects reduced the time to reach the boundary, the filled area and the roundness. The proposed method provides a novel tool for quick, robust differentiation between various cement formulations through the visualization and quantitative analysis of the cement spreading at various time intervals.

  • 2.
    Carlsson, Elin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mestres, Gemma
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Treerattrakoon, Kiatnida
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Lopez, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Karlsson Ott, Marjam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Larsson, Sune
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    In vitro and in vivo response to low-modulus PMMA-based bone cement2015In: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, article id 594284Article in journal (Refereed)
    Abstract [en]

    The high stiffness of acrylic bone cements has been hypothesized to contribute to the increased number of fractures encountered after vertebroplasty, which has led to the development of low-modulus cements. However, there is no data available on the in vivo biocompatibility of any low-modulus cement. In this study, the in vitro cytotoxicity and in vivo biocompatibility of two types of low-modulus acrylic cements, one modified with castor oil and one with linoleic acid, were evaluated using human osteoblast-like cells and a rodent model, respectively. While the in vitro cytotoxicity appeared somewhat affected by the castor oil and linoleic acid additions, no difference could be found in the in vivo response to these cements in comparison to the base, commercially available cement, in terms of histology and flow cytometry analysis of the presence of immune cells. Furthermore, the in vivo radiopacity of the cements appeared unaltered. While these results are promising, the mechanical behavior of these cements in vivo remains to be investigated.

  • 3.
    Engstrand, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Polyhedral oligomeric silsesquioxane (POSS)–poly(ethylene glycol) (PEG) hybrids as injectable biomaterials2012In: Biomedical Materials, ISSN 1748-6041, E-ISSN 1748-605X, Vol. 7, no 3, p. 035013-Article in journal (Refereed)
    Abstract [en]

    One of the major issues with the currently available injectable biomaterials for hard tissue replacement is the mismatch between their mechanical properties and those of the surrounding bone. Hybrid bone cements that combine the benefits of tough polymeric and bioactive ceramic materials could become a good alternative. In this work, polyhedral oligomeric silsesquioxane (POSS) was copolymerized with poly(ethylene glycol) (PEG) to form injectable in situ cross-linkable hybrid cements. The hybrids were characterized in terms of their mechanical, rheological, handling and in vitro bioactive properties. The results indicated that hybridization improves the mechanical and bioactive properties of POSS and PEG. The Young moduli of the hybrids were lower than those of commercial cements and more similar to those of cancellous bone. Furthermore, the strength of the hybrids was similar to that of commercial cements. Calcium deficient hydroxyapatite grew on the surface of the hybrids after 28 days in PBS, indicating bioactivity. The study showed that PEG–POSS-based hybrid materials are a promising alternative to commercial bone cements.

  • 4.
    Hoess, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ott, Marjam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Comparison of a quasi-dynamic and a static extraction method for the cytotoxic evaluation of acrylic bone cements2016In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 62, p. 274-282Article in journal (Refereed)
    Abstract [en]

    In this study, two different extraction approaches were compared in order to evaluate the cytotoxicity of 7 different acrylic bone cements, mainly developed for spinal applications, to osteoblastic cells. Firstly, a static extraction was carried out continuously over 24 h, a method widely used in literature. Secondly, a quasi-dynamic extraction method that allowed the investigation of time-dependent cytotoxic effects of curing acrylic bone cements to cells was introduced. In both cases the extraction of the cements was started at a very early stage of the polymerization process to simulate the conditions during clinical application. Data obtained by the quasi-dynamic extraction method suggest that the cytotoxicity of the setting materials mainly originates from the release of toxic components during the first hour of the polymerization reaction. It was also shown that a static extraction over 24 h generally represents this initial stage of the curing process. Furthermore, compared to the static extraction, time dependent cytotoxicity profiles could be detected using the quasi-dynamic extraction method. Specifically, a modification of commercial Osteopal (R) V with castor oil as a plasticizer as well as a customized cement formulation showed clear differences in cytotoxic behavior compared to the other materials during the setting process. In addition, it was observed that unreacted monomer released from the castor oil modified cement was not the main component affecting the toxicity of the material extracts. The quasi-dynamic extraction method is a useful tool to get deeper insight into the cytotoxic potential of curing acrylic bone cements under relevant biological conditions, allowing systematic optimization of materials under development.

  • 5.
    Hoess, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effects of a natural oil on the mechanical properties and cytotoxicity of PMMA bone cement2011In: Annual Meeting of the Scandinavian Society for Biomaterials, 2011, Vol. 21, no S1, p. 23-Conference paper (Refereed)
  • 6.
    Holub, Ondrej
    et al.
    University of Leeds.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Borse, Vishal
    University of Leeds.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kapur, Nik
    University of Leeds.
    Hall, Richard M.
    University of Leeds.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Biomechanics of low-modulus and standard acrylic bone cements in simulated vertebroplasty: A human ex vivo study2015In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 48, no 12, p. 3258-3266Article in journal (Refereed)
    Abstract [en]

    The high stiffness of bone cements used in vertebroplasty has been hypothesised to contribute to the propensity of adjacent vertebral fractures after treatment. Therefore, new low-modulus cements have been developed; however, there are currently no studies assessing the biomechanical aspects of vertebroplasty with these cements in an ex vivo non-prophylactic model. In this study, we induced wedge fractures through eccentric uniaxial compression to single whole-vertebrae, before and after augmentation with either standard or low-modulus cement. Compressive strength and stiffness of individual vertebrae were measured, on 19 samples from metastatic spines and 20 samples from elderly, osteopenic spines. While both cement types increased the strength of both the metastatic (+34% and +63% for standard and low-modulus cement, respectively) and the elderly vertebrae (+303% and +113%, respectively), none of them restored the initial stiffness of metastatic specimens (−51% and −46%, respectively). Furthermore, low-modulus cement gave a lower total stiffness (−13%) of elderly specimens whereas standard cement increased it above initial levels (+17%). Results show that vertebroplasty with low-modulus cement could provide restoration of the initial stiffness while increasing the strength of fractured elderly vertebrae and hence represent a treatment modality which is closer to pre-augmented behaviour. Also, this study indicates that stiffness-modified cement needs to be optimised for patient/pathology specific treatment.

  • 7.
    Koh, Ilsoo
    et al.
    ETH, Inst Biomech, CH-8093 Zurich, Switzerland.
    Lopez, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Pinar, Ana. B.
    ETH, Lab Crystallog, CH-8093 Zurich, Switzerland.
    Helgason, Benedikt
    ETH, Inst Biomech, CH-8093 Zurich, Switzerland.
    Ferguson, Stephen. J.
    ETH, Inst Biomech, CH-8093 Zurich, Switzerland.
    The effect of water on the mechanical properties of soluble and insoluble ceramic cements2015In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 51, p. 50-60Article in journal (Refereed)
    Abstract [en]

    Ceramic cements are good candidates for the stabilization of fractured bone due to their potential ease of application and biological advantages. New formulations of ceramic cements have been tested for their mechanical properties, including strength, stiffness, toughness and durability. The changes in the mechanical properties of a soluble cement (calcium sulfate) upon water-saturation (saturation) was reported in our previous study, highlighting the need to test ceramic cements using saturated samples. It is not clear if the changes in the mechanical properties of ceramic cements are exclusive to soluble cements. Therefore the aim of the present study was to observe the changes in the mechanical properties of soluble and insoluble ceramic cements upon saturation. A cement with high solubility (calcium sulfate dihydrate, CSD) and a cement with low solubility (dicalcium phosphate dihydrate, DCPD) were tested. Three-point bending tests were performed on four different groups of: saturated CSD, non-saturated CSD, saturated DCPD, and non-saturated DCPD samples. X-ray diffraction analysis and scanning electron microscopy were also performed on a sample from each group. Flexural strength, effective flexural modulus and flexural strain at maximum stress, lattice volume, and crystal sizes and shape were compared, independently, between saturated and non-saturated groups of CSD and DCPD. Although material dissolution did not occur in all cases, all calculated mechanical properties decreased significantly in both CSD and DCPD upon saturation. The results indicate that the reductions in the mechanical properties of saturated ceramic cements are not dependent on the solubility of a ceramic cement. The outcome raised the importance of testing any implantable ceramic cements in saturated condition to estimate its in vivo mechanical properties. (C) 2015 Elsevier Ltd. All rights reserved.

  • 8.
    Koh, Ilsoo
    et al.
    ETH Zurich.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Helgason, Benedikt
    ETH Zurich.
    Ferguson, Stephen J.
    ETH Zurich.
    The compressive modulus and strength of saturated calcium sulphate dihydrate cements: Implications for testing standards2014In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 34, p. 187-198Article in journal (Refereed)
    Abstract [en]

    Calcium sulphate-based bone cement is a bone filler with proven biological advantages including biodegradability, biocompatibility and osteoconductivity. Mechanical properties of such brittle ceramic cements are frequently determined using the testing standard designed for ductile acrylic cements. The aims of the study were (1) to validate the suitability of this common testing protocol using saturated calcium sulphate dihydrate (CSD), and (2) to compare the strength and effective modulus of non-saturated and saturated CSD, in order to determine the changes in the mechanical behavior of CSD upon saturation. Unconfined compression tests to failure were performed on 190 cylind- rical CSD samples. The samples were divided into four groups having different saturation levels (saturated, non-saturated) and end conditions (capped and non-capped). Two effective moduli were calculated per sample, based on the deformations measured using the machine platens and a sample-mounted extensometer. The effective moduli of non-saturated groups were found to be independent of the end conditions. The saturated and capped group showed no difference in the effective moduli derived from different measurement methods, while the saturated and non-capped group showed a significant difference between the machine platen- and extensometer-derived moduli. Strength and modulus values were significantly lower for saturated samples. It was assumed that the existence of water in saturated CSD alters the mechanical response of the material due to the changes in chemical and physical behaviors. These factors are considered to play important roles to decrease the shear strength of CSD. It was proposed that the reduction in CSD shear strength evokes local deformation at the platen–sample boundary, affecting the strength and effective moduli derived from the experiments. The results of this study highlighted the importance of appropriate and consistent testing methods when determining the mechanical properties of saturated ceramic cements.

  • 9.
    Lopez, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mestres, Gemma
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Karlsson Ott, Marjam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ferguson, SJ
    Helgason, B
    Persson, Cecilia
    Mechanical and in vitro evaluation of low-modulus bone cement - Osteopal®V modified with linoleic acid2012Conference paper (Refereed)
  • 10. Lukaszczyk, Jan
    et al.
    Janicki, Bartosz
    Lopez, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Skolucka, Karolina
    Wojdyla, Henryk
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Piaskowski, Sylwester
    Smiga-Matuszowicz, Monika
    Novel injectable biomaterials for bone augmentation based on isosorbide dimethacrylic monomers2014In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 40, p. 76-84Article in journal (Refereed)
    Abstract [en]

    Drawbacks with the commonly used PMMA-based bone cements, such as an excessive elastic modulus and potentially toxic residual monomer content, motivate the development of alternative cements. In this work an attempt to prepare an injectable biomaterial based on isosorbide-alicyclic diol derived from renewable resources was presented. Two novel dimethacrylic monomers ISDGMA - 2,5-bis(2-hydroxy-3-methacryloyloxypropoxy)-1,4:3,6-dianhydro-sorbitol and ISETDMA - dimethacrylate of ethoxylated isosorbide were synthesized and used to prepare a series of low-viscosity compositions comprising bioactive nano-sized hydroxyapatite in the form of a two-paste system. Formulations exhibited a non-Newtonian shear-thinning behavior, setting times between 2.6 min and 53 min at 37 degrees C and maximum curing temperatures of 65 degrees C. Due to the hydrophilic nature of ISDGMA, cured compositions could absorb up to 13.6% water and as a result the Young's modulus decreased from 1429 MPa down to 470 MPa. Both, poly(ISDGMA) and poly(ISETDMA) were subjected to a MU study on mice fibroblasts (BALB/3T3) and gave relative cell viabilities above 70% of control. A selected model bone cement was additionally investigated using human osteosarcoma cells (SaOS-2) in an MTS test, which exhibited concentration-dependent cell viability. The preliminary results, presented in this work reveal the potential of two novel dimethacrylic monomers in the preparation of an injectable biomaterial for bone augmentation, which could overcome some of the drawbacks typical for conventional acrylic bone cement. (C) 2014 Elsevier B.V. All rights reserved.

  • 11.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Injectable Biomaterials for Spinal Applications2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The use of injectable biomaterials is growing as the demands for minimally invasive procedures, and more easily applicable implants become higher, but their availability is still limited due to the difficulties associated to their design.

    Each year, more than 700,000 vertebral compression fractures (VCF’s) are reported in the US and 500,000 VCF’s in Europe due to primary osteoporosis only. VCF’s can compromise the delicacy of the spinal canal and also cause back pain, which affects the patient’s quality of life. Vertebroplasty was developed in the 80’s, and has proven to be a safe minimally invasive procedure that can, quickly and sustainably, relieve the pain in patients experiencing VCF’s. However, biomaterials for vertebroplasty still have limitations. For instance, ceramic bone cements are difficult to distinguish from the bone using X-ray techniques. On the other hand, acrylic bone cements may cause adjacent vertebral fractures (AVF’s). Large clinical studies have indicated that 12 to 20% vertebroplasty recipients developed subsequent vertebral fractures, and that 41 to 67% of these, were AVF’s. This may be attributed to the load shifting and increased pressure on the adjacent endplates reached after vertebroplasty with stiff cements.

    The primary aim of this thesis was to develop better injectable biomaterials for spinal applications, particularly, bone cements for vertebroplasty. Water-soluble radiopacifiers were first investigated to enhance the radiopacity of resorbable ceramic cements. Additionally, different strategies to produce materials that mechanically comply with the surrounding tissues (low-modulus bone cements) were investigated. When a suitable low-modulus cement was produced, its performance was evaluated in both bovine bone, and human vertebra ex vivo models.

    In summary, strontium halides showed potential as water-soluble radiocontrast agents and could be used in resorbable calcium phosphates and other types of resorbable biomaterials. Conversely, linoleic acid-modified (low-modulus) cements appeared to be a promising alternative to currently available high-modulus cements. It was also shown that the influence of the cement properties on the strength and stiffness of a single vertebra depend upon the initial bone volume fraction, and that at low bone volume fractions, the initial mechanical properties of the vertebroplasty cement become more relevant. Finally, it was shown that vertebroplasty with low-modulus cements is biomechanically safe, and could become a recommended minimally invasive therapy in selected cases, especially for patients suffering from vertebral compression fractures due to osteoporosis.

  • 12.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engstrand, Johanna
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Bioactive hybrids based on polyhedral oligomeric silsesquioxane intended as bone fillers2012In: 9th World Biomaterials Congress, Chengdu China, June 1-5, 2012, 2012Conference paper (Refereed)
  • 13.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Filho, Luimar Correa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Cogrel, Mathilde
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Schmidt, Susann
    Linköping University.
    Högberg, Hans
    Linköping University.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Morphology and adhesion of silicon nitride coatings upon soaking in fetal bovine serum2018In: 15th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering and 3rd Conference on Imaging and Visualization, Lisbon, March 26-29, 2018 / [ed] P. R. Fernandes and J. M. Tavares, 2018, article id 116Conference paper (Refereed)
    Abstract [en]

    Total hip joint replacements are considered successful in providing patients with close- to-normal lives; however, revision surgeries still represent an individual and socioeconomic burden due to wear and failure of the implants, which occurs at a rate of 3-10% at 10 years. Therefore, eorts are being made to increase the lifespan of articial prostheses. Because of the impossibility to avoid wear debris, functional silicon nitride coatings are being developed due their low wearing, particle solubility and good biological response. However, a compromise needs to be found between coating reactivity and durability.

    A HIPIMS process was used to sputter a CrN interlayer followed by a SiNx top layer using 1- and 3-fold rotation in an industrial deposition system (CemeCon AG, Würselen, Germany). In order to measure the adhesion of the coatings to the cobalt-chromium-molybdenum substrates a scratch test was used, consisting of generating a scratch with a Rockwell C diamond stylus, at an increasing load from 0 to 100 N, at a displacement rate of 6mm/min. The samples were immersed in 25% fetal bovine serum solution to mimic synovial joint uid and scratched aer 0, 1, 3, 6 weeks periods in this solution. The cross-section of the coatings was assessed through Focused Ion Beam at 30kV for milling and 5kV for secondary electron imaging of the surface.

    The coatings demonstrated a high nitrogen content, previously shown to be benecial in terms of low dissolution rates. The deposition conditions and coating morphology were found to have an eect on the dissolution rate and thereby also the spallation failure of the coatings. These results are informative for the further development of these coatings into parts of functional 3D implants. 

  • 14.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hoess, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Fathali, Hoda
    Ott, Marjam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Acrylic bone cement modified with oligo (trimethylene carbonate)2012In: 5th Annual Meeting of the Scandinavian Society for Biomaterials, Uppsala Sweden, May 8-9, 2012, 2012Conference paper (Refereed)
  • 15.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hoess, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Thersleff, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ott, Marjam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Low-modulus PMMA bone cement modified with castor oil2011In: Bio-medical materials and engineering, ISSN 0959-2989, E-ISSN 1878-3619, Vol. 21, no 5-6, p. 323-332Article in journal (Refereed)
    Abstract [en]

    Some of the current clinical and biomechanical data suggest that vertebroplasty causes the development of adjacent vertebral fractures shortly after augmentation. These findings have been attributed to high injection volumes as well as high Young’s moduli of PMMA bone cements compared to that of the osteoporotic cancellous bone. The aim of this study was to evaluate the use of castor oil as a plasticizer for PMMA bone cements. The Young’s modulus, yield strength, maximum polymerization temperature, doughing time, setting time and the complex viscosity curves during curing, were determined. The cytotoxicity of the materials extracts was assessed on cells of an osteoblast-like cell line. The addition of up to 12 wt% castor oil decreased yield strength from 88 to 15 MPa, Young’s modulus from 1500 to 446 MPa and maximum polymerization temperature from 41.3 to 25.6◦C, without affecting the setting time. However, castor oil seemed to interfere with the polymerization reaction, giving a negative effect on cell viability in a worst-case scenario.

  • 16.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mestres, Gemma
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Karlsson Ott, Marjam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ferguson, Stephen J
    Swiss Federal Institute of Technology.
    Helgason, Benedikt
    Swiss Federal Institute of Technology.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mechanical and in vitro evaluation of low-modulus bone cement - Osteopal®V modified with linoleic acid2013In: European Cells and Materials, ISSN 1473-2262, E-ISSN 1473-2262Article in journal (Refereed)
  • 17.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mestres, Gemma
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Karlsson Ott, Marjam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ferguson, Stephen J.
    ETH Zurich.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Helgason, Benedikt
    ETH Zurich.
    Compressive mechanical properties and cytocompatibility of bone-compliant, linoleic acid-modified bone cement in a bovine model2014In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 32, p. 245-256Article in journal (Refereed)
    Abstract [en]

    Adjacent vertebral fractures are a common complication experienced by osteoporosis patients shortly after vertebroplasty. Whether these fractures are due to the bone cement properties, the cement filling characteristics or to the natural course of the disease is still unclear. However, some data suggests that such fractures might occur because of an imbalance in the load distribution due to a mismatch between the elastic modulus (E) of the bone-cement composite, and that of the vertebral cancellous bone. In this study, the properties of bone-compliant linoleic acid-modified bone cements were assessed using a bovine vertebroplasty model. Two groups of specimens (cement-only and bone-cement composites), and four subgroups comprising bone cements with elastic moduli in the range of 870-3500 MPa were tested to failure in uniaxial compression. In addition, monomer release as well as time and concentration-dependent cytocompatibility was assessed through the cement extracts using a Saos-2 cell model. Composites augmented with bone-compliant cements exhibited a reduction in E despite their relatively high bone volume fraction (BVF). Moreover, a significant positive correlation between the BVF and the E for the composites augmented with 870 MPa modulus cements was found. This was attributed to the increased relative contribution of the bone to the mechanical properties of the composites with a decrease in E of the bone cement. The use of linoleic acid reduced monomer conversion resulting in six times more monomer released after 24 h. However, the cytocompatibility of the bone-compliant cements was comparable to that of the unmodified cements after the extracts were diluted four times. This study represents an important step towards introducing viable bone-compliant bone cements into vertebroplasty practice.

  • 18.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Montazerolghaem, Maryam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ott, Marjam Karlsson
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Calcium phosphate cements with strontium halides as radiopacifiers2014In: Journal of Biomedical Materials Research. Part B - Applied biomaterials, ISSN 1552-4973, E-ISSN 1552-4981, Vol. 102, no 2, p. 250-259Article in journal (Refereed)
    Abstract [en]

    High radiopacity is required to monitor the delivery and positioning of injectable implants. Inorganic nonsoluble radiopacifiers are typically used in nondegradable bone cements; however, their usefulness in resorbable cements is limited due to their low solubility. Strontium halides, except strontium fluoride, are ionic water-soluble compounds that possess potential as radiopacifiers. In this study, we compare the radiopacity, mechanical properties, composition, and cytotoxicity of radiopaque brushite cements prepared with strontium fluoride (SrF2), strontium chloride (SrCl2·6H2O), strontium bromide (SrBr2), or strontium iodide (SrI2). Brushite cements containing 10 wt % SrCl2·6H2O, SrBr2, or SrI2 exhibited equal to or higher radiopacity than commercial radiopaque cements. Furthermore, the brushite crystal lattice in cements that contained the ionic radiopacifiers was larger than in unmodified cements and in cements that contained SrF2, indicating strontium substitution. Despite the fact that the strontium halides increased the solubility of the cements and affected their mechanical properties, calcium phosphate cements containing SrCl2·6H2O, SrBr2, and SrI2 showed no significant differences in Saos-2 cell viability and proliferation with respect to the control. Strontium halides: SrCl2·6H2O, SrBr2, and SrI2 may be potential candidates as radiopacifiers in resorbable biomaterials although their in vivo biocompatibility, when incorporated into injectable implants, is yet to be assessed.

  • 19.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Montazerolghaem, Maryam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Marjam, Ott
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Strontium halides as degradable radiopacifiers2012In: The 22nd Interdisciplinary Research Conference on Injectable Osteoarticular Biomaterials and Bone, 2012Conference paper (Refereed)
  • 20.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Injectable biodegradable composites for the degenerated intervertebral disc2010In: GRIBOI Congress, Turin, 2010, 2010Conference paper (Refereed)
  • 21.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Synthesis and characterization of injectable composites of poly[D,L-lactide-co-(ε-caprolactone)] reinforced with β-TCP and CaCO3 for intervertebral disk augmentation.2010In: Journal of Biomedical Materials Research, Part B: Applied Biomaterials, ISSN 15524973, Vol. 95B, no 1, p. 75-83Article in journal (Refereed)
    Abstract [en]

    Degeneration of the intervertebral disk constitutes one of the major causes of low back pain in adults aged 2050 years old. In this study, injectable, in situ setting, degradable composites aimed for intervertebral disk replacement were prepared. beta-TCP and calcium carbonate particles were mixed into acrylic-terminated oligo[D,L-lactide-co-(epsilon-caprolactone)], which were crosslinked at room temperature. The structure of the oligomers was confirmed by H-1-NMR spectroscopy. The composites were examined via SEM, and the mechanical properties of the crosslinked networks were determined. The porous beta-TCP particles showed good mechanical anchorage to the matrix due to polymer penetration into the pores. In vitro degradation tests showed that the composites containing beta-TCP slowly degraded, whereas the composites containing CaCO3 exhibited apatite formation capacity. It was concluded that the surface area, morphology, and solubility of the fillers might be used to control the degradation properties. The incorporation of fillers also increased both the elastic modulus and the maximum compression strength of the composites, properties that were similar to those of the physiological disk. These materials have potential for long-term intervertebral disk replacement and regenerative scaffolds because of their low degradation rates, bioactivity, and mechanical properties.

  • 22.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Rojas, Ramiro
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Comparative characterization of oligomeric precursors intended for injectable implants2013In: Polymers for Advanced Technologies, ISSN 1042-7147, E-ISSN 1099-1581, Vol. 24, no 1, p. 15-21Article in journal (Refereed)
    Abstract [en]

    The use of injectable materials is a simple approach for drug delivery and tissue repair, in, e.g. minimally invasive surgery applications. If these materials are used past their glass transition temperature and have a low viscosity, they will be able to flow while delivered in situ. Whether these materials are to be used as low viscosity drug carriers or further crosslinked for tissue repair, there is a need for a better understanding of their handling properties. In this study, oligo(trimethylene carbonate) (oTMC) and oligo[D,L-lactide-co-(«-caprolactone)] (oDLLA-co-CL) of various molecular weights within a relevant injectability range were synthesized via ring-opening polymerization. The materials were comparatively characterized by 1H NMR spectroscopy, differential scanning calorimetry, gel permeation chromatography, and rheological measurements. After comparing the viscosities and molecular weights of the materials, it was concluded that oDLLA-co-CLs were, gener- ally, better suited as an injectable in situ crosslinking network, whereas oTMCs were found to be better candidates as injectable drug carriers. This study provides useful data and guidelines on the use of these and other similar oligomers intended for injectable implants.

  • 23.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Unosson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Direct and interactive effects of three variables on properties of PMMA bone cement for vertebral body augmentation2011In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 22, no 6, p. 1599-1606Article in journal (Refereed)
    Abstract [en]

    PMMA bone cements are widely used for vertebral body augmentation procedures vertebroplasty and balloon kyphoplasty. Although there are studies in the literature on the direct effects of relevant variables on the properties of these cements, there are none on the interactive effects. In the present work, such a study was performed on both types of effects, with the variables being the concentration of initiator (benzoyl peroxide), the concentration of crosslinker (ethylene glycol dimethacrylate), and the liquid-to-powder ratio used in preparing the cement; and the properties being the compressive strength, the compressive modulus, the doughing time, the setting time, and the maximum polymerization temperature. Two additional properties obtained from the viscosity-versustime curves, namely the time at the onset of curing, and the critical curing rate were also studied. Significant interactive effects between the amount of crosslinker and the amount of radical initiator were found to affect the doughing time and the critical curing rate. These effects were explained in terms of the reaction kinetics. It was concluded that interactive effects may exist and should be taken into account when designing bone cement formulations.

  • 24.
    Persson, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The effect of castor oil on spinal bone cement properties2011In: The 57th Annual Meeting of the Orthopaedic Research Society, Long Beach, California, 2011Conference paper (Refereed)
  • 25.
    Persson, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The effect of castor oil on spinal bone cement properties2011Conference paper (Refereed)
  • 26.
    Persson, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Fathali, Hoda
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hoess, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Rojas, Ramiro
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The effect of oligo(trimethylene carbonate) addition on the stiffness of acrylic bone cement2016In: Biomatter, ISSN 2159-2527, E-ISSN 2159-2535, Vol. 6, no 1, article id 1133394Article in journal (Refereed)
    Abstract [en]

    With the increasing elderly population an increase in the number of bony fractures associated toage-related diseases such as osteoporosis also follows. The relatively high stiffness of the acrylicbone cements used in these patients has been suggested to give raise to a suboptimal loaddistribution surrounding the cementin vivo, and hence contribute to clinical complications, such asadditional fractures. The aim of this study was to develop a low-modulus bone cement, based oncurrently used, commercially available poly(methyl methacrylate) (PMMA) cements forvertebroplasty. To this end, acrylate end-functionalized oligo(trimethylene carbonate) (oTMC) wasincorporated into the cements, and the resulting compressive mechanical properties wereevaluated, as well as the cytotoxic and handling properties of selected formulations. Sixteenwt%oTMC was needed in the vertebroplastic cement Osteopal V to achieve an elastic modulus of1063 MPa (SD 74), which gave a corresponding compressive strength of 46.1 MPa (SD 1.9). Cementextracts taken at 1 and 12 hours gave a reduced MG-63 cell viability in most cases, while extractstaken at 24 hours had no significant effect on cell behavior. The modification also gave an increasein setting time, from 14.7 min (SD 1.7) to 18.0 min (SD 0.9), and a decrease in maximumpolymerization temperature, from 41.5C (SD 3.4) to 30.7C (SD 1.4). While further evaluation ofother relevant properties, such as injectability andin vivobiocompatibility, remains to be done, theresults presented herein are promising in terms of approaching clinically applicable bone cementswith a lower stiffness.

  • 27.
    Persson, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hoess, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ott, Marjam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Towards Low-Modulus Bone Cements – The Effect of a Natural Oil in PMMA2011Conference paper (Refereed)
  • 28.
    Persson, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Unosson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Customised bone cement for vertebroplasty2010Conference paper (Refereed)
  • 29.
    Persson, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Unosson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Customised Bone Cement for Vertebroplasty2010In: Interfacing biology and materials, 2010Conference paper (Refereed)
  • 30.
    Persson, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Robert, Elise
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Carlsson, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Robo, Céline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lopez, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Godoy-Gallardo, Maria
    Technical University of Catalonia, Spain.
    Ginebra, Maria-Pau
    Technical University of Catalonia, Spain.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The effect of unsaturated fatty acid and triglyceride oil addition on the mechanical and antibacterial properties of acrylic bone cements2015In: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 30, no 3, p. 279-289Article in journal (Refereed)
  • 31.
    Qin, Tao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lopez, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Öhman, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Enhanced drug delivery of antibiotic-loaded acrylic bone cements using calcium phosphate spheres2015In: Journal of Applied Biomaterials & Functional Materials, ISSN 2280-8000, E-ISSN 2280-8000, Vol. 13, no 3, p. E241-E247Article in journal (Refereed)
    Abstract [en]

    Background: Local infection near an implant may pose a serious problem for patients. Antibiotic delivery from acrylic (poly(methyl methacrylate)-based) cements is commonly used to prevent and treat infections in the proximity of, e.g., hip joint implants. However, at present, the drug release properties of PMMA cements are not optimal. An initial burst followed by very slow release means that an unnecessarily large amount of antibiotic needs to be added to the cement, increasing the risk of bacterial resistance. The main purpose of this study was to enhance drug delivery from PMMA cements without influencing the mechanical properties. Methods: We incorporated strontium-doped calcium phosphate spheres (SCPS) into PMMA cement to enhance the antibiotic release and potentially improve the bone-cement integration. The release of strontium and vancomycin was investigated using inductively coupled plasma atomic emission spectroscopy and UV spectrophotometry, respectively. Results: It was found that incorporating SCPS into PMMA could enhance the antibiotic release and deliver strontium ions to the surroundings. The incorporation of SCPS also increased the radiopacity as well as the working time of the cement. The compressive strength and Young's modulus were not affected. Conclusions: Our results showed that SCPS/PMMA antibiotic-loaded cement had enhanced antibiotic release, delivered strontium ions and maintained mechanical properties, indicating that the SCPS additive could be a good alternative for controlling the drug-delivery properties of PMMA cement.

  • 32.
    Widmer Soyka, Rene P.
    et al.
    Swiss Federal Institute of Technology.
    López, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Cristofolini, Luca
    University of Bologna.
    Ferguson, Stephen J.
    Swiss Federal Institute of Technology.
    Numerical description and experimental validation of a rheology model for non-Newtonian fluid flow in cancellous bone2013In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 27, p. 43-53Article in journal (Refereed)
    Abstract [en]

    Fluids present or used in biology, medicine and (biomedical) engineering are often significantly non-Newtonian. Furthermore, they are chemically complex and can interact with the porous matrix through which they flow. The porous structures themselves display complex morphological inhomogeneities on a wide range of length scales. In vertebroplasty, a shear-thinning fluid, e.g. poly(methyl methacrylate) (PMMA), is injected into the cavities of vertebral trabecular bone for the stabilization of fractures and metastatic lesions. The main objective of this study was therefore to provide a protocol for numerically investigating the rheological properties of PMMA-based bone cements to predict its spreading behavior while flowing through vertebral trabecular bone. A numerical upscaling scheme based on a dimensionless formulation of the Navier-Stokes equation is proposed in order to relate the pore-scale rheological properties of the PMMA that were experimentally estimated using a plate rheometer, to the continuum-scale. On the pore length scale, a viscosity change on the order of one magnitude was observed whilst, the shear-thinning properties caused a viscosity change on the order of only 10% on the continuum length scale and in a flow regime that is relevant for vertebroplasty. An experimental validation, performed on human cadaveric vertebrae (n=9), showed a significant improvement of the cement spreading prediction accuracy with a non-Newtonian formulation. A root mean square cement surface prediction error of 1.53 mm (assuming a Newtonian fluid) and 1.37 mm (assuming a shear-thinning fluid) was found. Our findings highlight the importance of incorporating the non-Newtonian fluids properties in computational models of porous media at the appropriate length scale. 

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