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    Item type:Publication, Access status: without files ,
    Effects of long-term alendronate treatment on bone mineralisation, resorption parameters and biomechanics of single human vertebral trabeculae
    (University of Wales, 2014)
    Krause, Matthias
    ;
    Soltau, M.
    ;
    Zimmermann, Elizabeth A.
    ;
    Hahn, Michael
    ;
    Kornet, Jacob Jan
    Due to their well-established fracture risk reduction, bisphosphonates are the most frequently used therapeutic agent to treat osteoporosis. Bisphosphonates reduce fracture risk by suppressing bone resorption, but the lower bone turnover could have a negative impact on bone quality at the tissue level. Here, we directly assess the structural and mechanical characteristics of cancellous bone from the lumbar vertebrae (L5) in non-treated osteoporotic controls (n = 21), mid-term alendronate-treated osteoporotic patients (n = 6), and long-term alendronate-treated osteoporotic patients (n = 7). The strength and toughness of single trabeculae were evaluated, while the structure was characterised through measurements of microdamage accumulation, mineralisation distribution, and histological indices. The alendronate-treated cases had a reduced eroded surface (ES/BS, p < 0.001) and a higher bone mineralisation in comparison to non-treated controls (p = 0.037), which is indicative of low turnover associated with treatment. However, the amount of microdamage and the mechanical properties were similar among the control and treatment groups. As the tissue mineral density (TMD) increased significantly with alendronate treatment compared to non-treated osteoporotic controls, the reduction in resorption cavities could counterbalance the higher TMD allowing the alendronate-treated bone to maintain its mechanical properties and resist microdamage accumulation. A multivariate analysis of the possible predictors supports the theory that multiple factors (e.g., body mass index, TMD, and ES/BS) can impact the mechanical properties. Our results suggest that long-term alendronate treatment shows no adverse impact on mechanical cancellous bone characteristics.
    Publicationtype: Journal Article
    Scopus© Citations 15  64
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    Item type:Publication, Access status: with files ,
    The development of the collagen fibre network in tissue-engineered cartilage constructs in vivo : engineered cartilage reorganises fibre network
    (University of Wales, 2012-04-05)
    Paetzold, Helge
    ;
    Goepfert, Christiane
    ;
    Huber, Gerd
    ;
    Hoenig, Elisa
    ;
    Pörtner, Ralf
    For long term durability of tissue-engineered cartilage implanted in vivo, the development of the collagen fibre network orientation is essential as well as the distribution of collagen, since expanded chondrocytes are known to synthesise collagen type I. Typically, these properties differ strongly between native and tissue-engineered cartilage. Nonetheless, the clinical results of a pilot study with implanted tissue-engineered cartilage in pigs were surprisingly good. The purpose of this study was therefore to analyse if the structure and composition of the artificial cartilage tissue changes in the first 52 weeks after implantation. Thus, collagen network orientation and collagen type distribution in tissue-engineered cartilage-carrier-constructs implanted in the knee joints of Göttinger minipigs for 2, 26 or 52 weeks have been further investigated by processing digitised microscopy images of histological sections. The comparison to native cartilage demonstrated that fibre orientation over the cartilage depth has a clear tendency towards native cartilage with increasing time of implantation. After 2 weeks, the collagen fibres of the superficial zone were oriented parallel to the articular surface with little anisotropy present in the middle and deep zones. Overall, fibre orientation and collagen distribution within the implants were less homogenous than in native cartilage tissue. Despite a relatively low number of specimens, the consistent observation of a continuous approximation to native tissue is very promising and suggests that it may not be necessary to engineer the perfect tissue for implantation but rather to provide an intermediate solution to help the body to heal itself.
    Publicationtype: Journal Article
    Scopus© Citations 6  422  379
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    Item type:Publication, Access status: without files ,
    In vivo tracking of segmental bone defect healing reveals that callus patterning is related to early mechanical stimuli
    (Forum Multimedia Publishing, 2012)
    Mehta, Manav
    ;
    Checa Esteban, Sara
    ;
    Lienau, Jasmin
    ;
    Hutmacher, Dietmar
    ;
    Duda, Georg
    This study addresses the hypothesis that callus formation, patterning, and mineralisation are impaired during the early phase of critical sized bone defect healing, and may relate to inter-fragmentary tissue strains within the bone defect area. Twenty four 12 week old Sprague Dawley rats were used for this study. They were divided into two groups defined by the femur bone defect size: (i) 1 mm resulting in normal healing (NH), and (ii) a large sized 5 mm defect resulting in critical healing (CH). Callus formation, patterning, and mineralisation kinetics in both groups were examined in the periosteal and osteotomy gap regions using a novel longitudinal study setup. Finite element analyses on μCT generated tomograms were used to determine inter-fragmentary tissue strain patterns and compared to callus formation and patterning over the course of time. Using a novel longitudinal study technique with μCT, in vivo tracking and computer simulation approaches, this study demonstrates that: (i) periosteal bone formation and patterning are significantly influenced by bone defect size as early as 2 weeks; (ii) osteotomy gap callus formation and patterning are influenced by bone defect size, and adapt towards a non-union in critical cases by deviating into a medullary formation route as early as 2 weeks after osteotomy; (iii) the new bone formation in the osteotomy gap enclosing the medullary cavity in the CH group is highly mineralised; (iv) inter-fragmentary strain patterns predicted during the very early soft callus tissue phase (less than 2 weeks) are concurrent with callus formation and patterning at later stages. In conclusion, bone defect size influences early onset of critical healing patterns.
    Publicationtype: Journal Article
      6
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    Item type:Publication, Access status: without files ,
    Tissue sparing hip implants
    (University of Wales, 2008-07-01)
    Bishop, Nicholas
    ;
    Morlock, Michael
    Publicationtype: Journal Article
      4