Simulation of bone replacement materials


Simulation of bone replacement materials

Gemming, S.

In the field of biomaterials, more specifically of materials which are used for medical implants, recent research is focused on the interface between implant material and biological environment. Among crystalline and glassy bone substitutes calcium- and phospho­rus-based oxides are of special interest, because their chemical composition can be adjusted to natural bone. Materials containing an appropriate ratio of oxides of calcium, phos­phorus and other physiologically compat­ible constitutents such as silicate and alkalis are bioactive and degradable in vivo. Therefore, the strategy in using such bone substitute implants is that these materials are slowly degraded inside the body and successively substituted by natural bone tissue.
Especially granular media with particles from appropriate calcium alkali orthophosphates, such as [Ca2KNa(PO4)2], exhibit a strongly en­han­ced biodegradability, but the sponge-like structure of the bone can not be remodelled with granulates. Yet, gene­ra­tive manufacturing techniques (rapid proto­typing) nowadays allow to build up even large, three-dimensional structures that are adapted to macro-/microscopic structural bone charac­te­ristics.
However, the natural bioactivity of calcium phosphates and related inorganic compounds is limited. bone remodelling is impeded, in particular when larger bone defects are to be restored by this class of material. Yet, the growth of bone tissue can significantly be stimulated by so-called Bone Morphogenetic Proteins (BMPs), proteins that are synthesized during build-up of bone tissue by the human body. Since a couple of years it has become possible to produce BMPs synthetically and couple them to surfaces of bone replacement materials. After the successful bioactivation of metallic Titanium-based prosthetic surfaces with BMP, the present study is devoted to elucidating the mechanism of protein coupling and especially the desorption kinetics of BMP on mineral surfaces.
Those experimental studies are accompanied by a scale-bridging simulation of the BMP sorption process from physiologic solution as a function of the local pH-value and the structure formation at the solid-liquid interface. With this knowledge the project BioMin yields a significant contribution to develop and manufacture tailored bone substitute implants, so that degradation of the substitute material and build-up of new bone tissue can go hand-in-hand in vivo.

Keywords: bone replacement; biomaterials; bioglasses; apatite; calcium phosphate; molecular modeling

  • Invited lecture (Conferences)
    Seminar on Topical Problems in Theoretical Physics, 16.12.2009, Chemnitz, Deutschland

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Publ.-Id: 13520