FABRICATION OF BIODEGRADABLE POLYMER SCAFFOLDS TO ENGINEER TRABECULARBONE

We present a novel method for manufacturing three-dimensional, biodegr adable poly(DL-lactic-co-glycolic acid) (PLGA) foam scaffolds for use in bone regeneration. The technique involves the formation of a compos ite material consisting of gelatin microspheres surrounded by a PLGA m atrix. The gelatin microspheres are leached out leaving an open-cell f oam with a pore size and morphology defined by the gelatin microsphere s. The foam porosity can be controlled by altering the volume fraction of gelatin used to make the composite material. PLGA 50:50 was used a s a model degradable polymer to establish the effect of porosity, pore size, and degradation on foam mechanical properties. The yield streng ths and moduli in compression of PLGA 50:50 foams were found to decrea se with increasing porosity according to power law relationships. Thes e mechanical properties were however, largely unaffected by pore size. Foams with yield strengths up to 3.2 MPa were manufactured. From in v itro degradation studies we established that for PLGA 50:50 foams the mechanical properties declined in parallel with the decrease in molecu lar weight. Below a weight average molecular weight of 10 000 the foam had very little mechanical strength (0.02 MPa). These results indicat e that PLGA 50:50 foams are not suitable for replacement of trabecular bone. However, the dependence of mechanical properties on porosity, p ore size, and degree of degradation which we have determined will aid us in designing a biodegradable scaffold suitable for bone regeneratio n.