3-DIMENSIONAL DEGRADABLE POROUS POLYMER-CERAMIC MATRICES FOR USE IN BONE REPAIR

A degradable polymer-ceramic matrix for use as a bone graft material i s described. The fabrication method used produces 3-dimensional macrop orous matrices which are structurally similar to cancellous bone in th eir porosity, mechanically similar to cancellous bone in compressive e lastic modulus and chemically comparable to the mineral matrix of bone in that they contain hydroxyapatite (HA). A 50:50 copolymer of poly(l actide/glycolide) (PLAGA) reinforced by a particulate calcium phosphat e ceramic, HA, was used to create a matrix composed of polymeric micro spheres. The channels between these spheres were pores approximately 1 00 mu m in diameter, Four polymer/ceramic ratios were used in matrix f abrication: 1:0, 1:1, 2.5:1, and 5:1. The mechanical behavior of the m aterial was found to vary with ceramic content. Increased levels of HA resulted in increased compressive elastic moduli. Prior to polymer de gradation, moduli ranged from a high of 1459 MPa (50% HA) to a low of 293 MPa (0% HA). Degradation studies over a 6-week period showed that 0 and 16.7% HA-containing matrices lost up to 50% of their original we ight, while the 28.6 and 50% HA-containing matrices lost up to 20% of their original weight. Increased HA matrix content translated into dec reased rates of matrix degradation. Environmental scanning electron mi croscopy (ESEM) confirmed that the polymer matrix contained pores that were interconnected during degradation. Viewed via ESEM, 10% HA conta ining matrices completely degraded by 6 weeks, while 50% HA matrices r emained relatively stable. These studies indicate that the porous 3-di mensional polymer/ceramic matrix may potentially be useful as a synthe tic material for bone repair.