Narrow Results

The purpose of this investigation was to prepare and evaluate the feasibility and biocompatibility of a new composite as a large defect bone substitute. The new GTGG was mainly composed of tricalcium phosphate ceramic particles and glutaraldehyde crosslinked gelatin in which Gui-Lu-Jiao was added (a mixture of Cervi Colla Cornus and Colla Plastri Testudinis). In the in vitro study, rat's calvaria osteoblasts were used to study bone characteristics upon exposure to different concentrations of the Gui-Lu-Jiao solution. In the in vivo study, GTGG composites were implanted into the defects of calvarial bones in mature New Zealand rabbits to test their osteogenerative characteristics. As a result, we found that Gui-Lu-Jiao added to the culture could promote the proliferation of osteoblasts. In addition, GTGG could induce a large amount of new bone growth in the rabbit's calvarial bone defect. Therefore, the GTGG composite might be a potential bone substitute.

This study evaluated the possibility of obtaining bioactive coatings on polyethylene/bioactive glass composites exhibiting a very good mechanical performance. High molecular weight polyethylene (HMWPE) was reinforced with 10 to 40% (wt.) of a bioactive glass (BGE1) and a glass-ceramic (BGE1C), in the SiO₂-3CaOP₂O₅-MgO system. The composites were compounded by twin-screw extrusion (TSE) and then injection moulded into dumb-bell tensile samples. The composites presenting adequate mechanical properties were then coated with a bioactive layer by two methodologies: (i) an adapted biomimetic route using a similar glass as a precursor of calcium-phosphate (Ca-P) film deposition, and (ii) the production of a ‘sandwich’ with bioactive glass particles, previously mixed with UHMWPE powders, made to adhere to both faces of tensile samples by compression moulding. The obtained results indicated that it is possible to produce composites presenting a modulus of 11.2 GPa coupled with a tensile strength of around 117 MPa. The developed composites could be coated with a Ca-P layer by an adapted biomimetic route. Furthemore, the ‘sandwich’ route allowed for the production of load-bearing composites, presenting a highly bioactive surface, which strongly adheres to the HMWPE matrix composites.

Various materials have been used for knee and hip prostheses over the last few decades due to considerations for their mechanical and tribological properties and their biocompatibility. Hydroxyapatite (HA) reinforced high density polyethylene (HDPE) composites have been developed as a new generation biomaterial for skeletal applications. In this investigation, the tribological properties (i.e., wear rate, coefficient of friction, and lubrication in the presence of proteins) of HDPE and HA/HDPE composites were evaluated against duplex stainless steel under dry and lubricated conditions. Lubricants included distilled water and aqueous solutions of proteins (egg albumen or glucose). It was found that HA/HDPE composites had lower coefficients of friction than HDPE under certain conditions. Furthermore, HDPE exhibited more severe fatigue failure marks than the composites. The degradation and fatigue failure due to the presence of proteins were severe for low speed wear testing (100 rpm) as compared to high speed wear testing (200 rpm). Both egg albumen and glucose were found to be corrosive to steel and adversely reactive for HDPE and HA/HDPE composites. This was clearly shown by SEM micrographs of HDPE and HA/HDPE specimen surfaces taken after the tests. The wear modes observed were similar to that of UHMWPE. Specimens tested with egg albumen also displayed higher wear rates, which again were attributed to corrosion accelerated wear of these specimens.