Schumacher, Ralf

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Schumacher
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Ralf
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Schumacher, Ralf

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2013 - 20177
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Typ: 01A - Beitrag in wissenschaftlicher Zeitschrift ×

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Gerade angezeigt 1 - 7 von 7
  • Vorschaubild nicht verfügbar
    Publikation
    Mechanical anisotropy of titanium scaffolds
    (De Gruyter, 2017) Weber, Franz E.; de Wild, Michael; Rüegg, Jasmine; Schumacher, Ralf [in: Current Directions in Biomedical Engineering]
    The clinical performance of an implant, e.g. for the treatment of large bone defects, depends on the implant material, anchorage, surface topography and chemistry, but also on the mechanical properties, like the stiffness. The latter can be adapted by the porosity. Whereas foams show isotropic mechanical properties, digitally modelled scaffolds can be designed with anisotropic behaviour. In this study, we designed and produced 3D scaffolds based on an orthogonal architecture and studied its angle-dependent stiffness. The aim was to produce scaffolds with different orientations of the microarchitecture by selective laser melting and compare the angle-specific mechanical behaviour with an in-silico simulation. The anisotropic characteristics of open-porous implants and technical limitations of the production process were studied.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Patient-specific hip prostheses designed by surgeons
    (De Gruyter, 30.09.2016) Coigny, Florian; Todor, Adrian; Rotaru, Horatiu; Schumacher, Ralf; Schkommodau, Erik [in: Current Directions in Biomedical Engineering]
    Patient-specific bone and joint replacement implants lead to better functional and aesthetic results than conventional methods [1], [2], [3]. But extracting 3D shape information from CT Data and designing individual implants is demanding and requires multiple surgeon-to-engineer interactions. For manufacturing purposes, Additive Manufacturing offers various advantages, especially for low volume manufacturing parts, such as patient specific implants. To ease these new approaches and to avoid surgeon-to-engineer interactions a new design software approach is needed which offers highly automated and user friendly planning steps.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    So profitiert die Medizintechnik vom 3D Druck
    (Springer, 27.01.2016) Moser, Silvio; Schumacher, Ralf [in: Produktion]
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Influence of microarchitecture on osteoconduction and mechanics of porous titanium scaffolds generated by selective laser melting
    (Mary Ann Liebert, 2016) de Wild, Michael; Zimmermann, Simon; Rüegg, Jasmine; Schumacher, Ralf; Fleischmann, Thea; Ghayor, Chafik; Weber, Franz E. [in: 3D Printing and Additive Manufacturing]
    Bone regeneration is naturally based on bone forming cells, osteoinduction by diverse growth factors, and osteoconduction. The latter one used as term in this study is the ingrowth of bone in 3D structures, which leads to an optimal case in creeping substitution of the scaffold by newly formed bone. Autologous bone is still the gold standard for bone substitutes. In most cases, newly developed bone substitutes consist of calcium phosphate, since hydroxyapatite is the main component of bone and mimics cancellous bone in microstructure. In this study, we wanted to elucidate the optimal microarchitecture for osteoconduction and determine compression strength and Young’s Modulus of the selected architectures. Selective laser melting of titanium was used as tool to generate diverse architectures in a repetitive and precise way. To link 3D scaffold architecture to biological readouts, bone ingrowth, bone to implant contact, and defect bridging of noncritical-sized defects in the calvarial bone of rabbits were determined. In this series, 5 different microarchitectures were tested with pore sizes ranging from 700 to 1300 lm and constrictions between 290 and 700 lm. To our surprise, all microstructures showed the same biological response of excellent osteoconduction. However, the mechanical yield strength of these structures differed by the factor of three and reached up to three times the strength of cancellous bone at a porosity of 72.3–88.4%. These results suggest that the microarchitecture of bone substitutes can be optimized toward mechanical strength in a wide range of constrictions and pore sizes without having a negative influence on osteoconduction.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Preliminary microstructural investigation of Mg produced by SLM
    (European Cells and Materials, 2016) Saxer, Sina; Rüegg, Jasmine; Dietschy, Alain; Schumacher, Ralf; de Wild, Michael; Wiese, Björn; Wohlfender, Fabian [in: European Cells and Materials]
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Rekonstruktion des dia-/metaphysären distalen Radius und der A. radialis bei Infektpseudoarthrose
    (Springer, 2015) Kolvenbach, Boris; Henning, Julia; Schumacher, Ralf; Schaefer, Dirk Johannes; Steiger, Regula; Honigmann, Philipp [in: Obere Extremität]
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Bone regeneration by the osteoconductivity of porous titanium implants manufactured by selective laser melting: A histological and µCT study in the rabbit
    (Mary Ann Liebert, 2013) de Wild, Michael; Schumacher, Ralf; Kyrill, Maier; Schkommodau, Erik; Thoma, Daniel; Bredell, Marius; Kruse, Astrid; Grätz, Klaus; Weber, Franz [in: Tissue Engineering. Part A]
    The treatment of large bone defects still poses a major challenge in orthopaedic and cranio-maxillofacial surgery. One possible solution could be the development of personalized porous titanium-based implants that are designed to meet all mechanical needs with a minimum amount of titanium and maximum osteopromotive properties so that it could be combined with growth factor-loaded hydrogels or cell constructs to realize advanced bone tissue engineering strategies. Such implants could prove useful for mandibular reconstruction, spinal fusion, the treatment of extended long bone defects, or to fill in gaps created on autograft harvesting. The aim of this study was to determine the mechanical properties and potential of bone formation of light weight implants generated by selective laser melting (SLM). We mainly focused on osteoconduction, as this is a key feature in bone healing and could serve as a back-up for osteoinduction and cell transplantation strategies. To that end, defined implants were produced by SLM, and their surfaces were left untreated, sandblasted, or sandblasted/acid etched. In vivo bone formation with the different implants was tested throughout calvarial defects in rabbits and compared with untreated defects. Analysis by micro computed tomography (µCT) and histomorphometry revealed that all generatively produced porous Ti structures were well osseointegrated into the surrounding bone. The histomorphometric analysis revealed that bone formation was significantly increased in all implant-treated groups compared with untreated defects and significantly increased in sand blasted implants compared with untreated ones. Bone bridging was significantly increased in sand blasted acid-etched scaffolds. Therefore, scaffolds manufactured by SLM should be surface treated. Bone augmentation beyond the original bone margins was only seen in implant-treated defects, indicating an osteoconductive potential of the implants that could be utilized clinically for bone augmentation purposes. Therefore, designed porous, lightweight structures have potential for bone regeneration and augmentation purposes, especially when complex and patient-specific geometries are essential.
    01A - Beitrag in wissenschaftlicher Zeitschrift