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Abstract

It was the purpose of this investigation to prove the biomechanical properties, the osteoconductive capacity and the degradation rate of alpha tricalcium phosphate (alpha TCP), a neutralized glass ceramics (GB9N) and a composite material (GB9N+copolymers). In a weight-bearing animal model six substitutes each were implanted in the medial tibial head of the right lower leg of adult Merino-sheep in a standardized surgical technique. After nine months the implants were harvested and prepared for histomorphological and histomorphometrical investigations (undecalcified Masson Goldner staining). For additional biomechanical testing of the specimens, non-operated bone blocks from the contralateral tibia as well as native implants served as controls. No significant differences for the maximum fracture load as well as for the yield strength were detected between harvested specimens and bone blocks from the contralateral tibia. However there were marked differences to ceramics that were not implanted. All substitutes showed osteoconduction, leading to a continuous ingrowth of new formed bone. However in the composite material soft tissue could be identified within the scaffold and there were signs of ongoing bone remodeling, nine months after implantation. The bone per tissue volume of alpha-TCP in conjunction to new bone (=percentage of trabecular bone volume plus percentage of residual substitute) was higher than for GB9N and the composite material. Nine months after implantation the percentage of residual alpha-TCP was 48%, it was 32% for GB9N and 28% for the composite. The intention of further studies should be to accelerate the degradation rates of substitutes and to improve biomechanical properties of implants by either modifying the chemical composition or combining materials with agents as, e.g. growth factors.

In Vitro and In Vivo Biocompatibility Studies of a Cast and Coated Titanium Alloy

“…A sufficient number of studies have shown that the sheep has a weight-bone ratio similar to that of humans. The bone structure as well as the immune, blood and lymphatic systems of sheep are largely homologous to those of humans [ 55 , 56 , 57 , 58 ]. This leads to our third step, the test in a critical size defect in sheep femoral condyle.…”

Mesenchymal Stem Cells and Platelet Gel Improve Bone Deposition within CAD-CAM Custom-Made Ceramic HA Scaffolds for Condyle Substitution

“…The 3D porous structure provides space for new bone formation, the support necessary for cells to proliferate and maintain their differential function, mimics many roles of the extracellular matrix, and its architecture defines the ultimate shape of new bone [5, 6]. …”