Surface porous fibre-reinforced composite bulk bone substitute
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Surface porous fibre-reinforced composite bulk bone substitute In vitro studies and in vivo evaluation in segment defect A.J. Aho1,2,*, M. Hautama¨ki1, R. Mattila1, P. Alander1, N. Strandberg2, J. Rekola1, J. Gunn1, L.V.J. Lassila1 and P.K. Vallittu1 1
Department of Prosthetic Dentistry and Biomaterials Research, Institute of Dentistry, University of Turku, Turku, Finland; 2Department of Surgery, Orthopaedic Unit, Turku University Central Hospital, Turku, Finland; *Author for correspondence (e-mail: allan.aho@fimnet.fi) Received 10 March 2004; accepted in revised form 27 April 2004
Key words: Artificial bone, Bioactive glass, Biomechanics, Bone healing, Fibre-reinforcement, Polymethylmetacrylate Prosthesis
Abstract The aim of this study was to describe and evaluate the significance of a porous surface with bioactive glass granules (S53P4) covering an artificial bulk material based on polymethylmetacrylate (PMMA) and fibrereinforced composite (FRC) technology. Effort was focused particularly on characters of the porous surface and biomechanical properties of the material in vitro, and test in vivo the implant in reconstruction in an experimental long bone segment defect model. The defect, 10 mm in length, created in the shaft of rabbit tibia, was reconstructed by the implant and fixed by intramedullary K-wires. The implant was incorporated within 4 weeks by new bone growth from the host bone covering particularly its posterior surface and cortex/implant junctions with bridging trabecular bone. Later, at 8 weeks, new bone was found also at the cortex/implant interface and in the medullary canal of the implant. Histometric measurements revealed direct bone/implant surface contact in 34% at the interface. Bioactive glass granules in the porous surface evoked the most direct contact with bone. The implants manufactured from PMMA only served as a control group, and showed significantly lower osteoconductive properties. Biomechanical measurements in vitro of fibre-reinforced PMMA specimens revealed values for bending strength and the flexural modulus to match them to human bone. This artificial bulk bone material based on PMMA/FRC technology seems to have proposing properties to be used as a bone substitute on load-bearing conditions.
Introduction To create a biomaterial simulating the structure and biological characters of bone would be worth of pursuit. A good bone substitute in bulk form – artificial bone – should be biocompatible and osteoconductive allowing attachment and bone growth on and into its surface porosities, and in addition its biomechanical properties should match to that of bone. Earlier studies (Galante et al. 1971; Bobyn et al. 1980) have focused to
characters of the surface structure and interfacial stability during the biological fixation between orthopaedic prosthesis and bone. Topography of roughened metal surface – grit-blasted, etched – and plasma-sprayed hydroxyapatite coatings have been means to enhance osseointegration and bone apposition on prosthesis surface (Hacking et al. 2002). The basic bulk
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