Studies on the development of a tissue e

Alternatives to conventional bone grafts are needed. Using a degradable polymer/ceramic composite system, our laboratory has developed porous matrices for use as trabecular bone graft replacements. Composed of 50:50 poly(lactide-co-glycolide) (PLAGA) and hydroxyapatite (HA), these matrices possess a three-dimensional (3D), porous structure based on microsphere technology. Our current studies examine the relationship between processing conditions and internal matrix structure. This has led to the development of three novel processes capable of fabricating a 3D porous structure: (1) a sintered microsphere method, (2) a solvent cast microsphere method, and (3) a gel microsphere method. Preliminary characterization of matrix structure was carried out by scanning electron microscopy (SEM). The solvent cast and sintered microsphere methods used prefabricated microspheres isolated through a solvent evaporation technique. SEM characterization of the sintered and solvent cast methods indicated a 3D network of fused microspheres with a range in pore diameter from 100-450 µm and 50-250 µm, respectively. The gel microsphere method also used microspheres from the solvent evaporation technique, however, matrices were created from microspheres isolated before complete solvent removal. SEM characterization indicated a 3D internal porous network ranging in size from 100-300 µm. It was determined that the porous structure was due to the aggregation of 'gel-like' microspheres.