HYDROXYAPATITE FIBER-REINFORCED POLY(ALPHA-HYDROXY ESTER) FOAMS FOR BONE REGENERATION

A process has been developed to manufacture biodegradable composite fo ams of poly(DL-lactic-co-glycolic acid) (PLGA) and hydroxyapatite shor t fibers for use in bone regeneration. The processing technique allows the manufacture of three-dimensional foam scaffolds and involves the formation of a composite material consisting of a porogen material (ei ther gelatin microspheres or salt particles) and hydroxyapatite short fibers embedded in a PLGA matrix. After the porogen is leached out, an open-cell composite foam remains which has a pore size and morphology defined by the porogen. By changing the weight fraction of the leacha ble component it was possible to produce composite foams with controll ed porosities ranging from 0.47 +/- 0.02 to 0.85 +/- 0.01 (n = 3). Up to a polymer:fiber ratio of 7:6, short hydroxyapatite fibers served to reinforce low-porosity PLGA foams manufactured using gelatin microsph eres as a porogen. Foams with a compressive yield strength up to 2.82 +/- 0.63 MPa (n = 3) and a porosity of 0.47 +/- 0.02 (n = 3) were manu factured using a polymer:fiber weight ratio of 7:6. In contrast, high- porosity composite foams (up to 0.81 +/- 0.02, n = 3) suitable for cel l seeding were not reinforced by the introduction of increasing quanti ties of hydroxyapatite short fibers. We were therefore able to manufac ture high-porosity foams which may be seeded with cells but which have minimal compressive yield strength, or low porosity foams with enhanc ed osteoconductivity and compressive yield strength. (C) 1998 Publishe d by Elsevier Science Ltd. All rights reserved.