IN-VIVO DEGRADATION OF A POLY(PROPYLENE FUMARATE) BETA-TRICALCIUM PHOSPHATE INJECTABLE COMPOSITE SCAFFOLD

This study was designed to investigate the in vivo biodegration and bi ocompatibility of a poly(propylene fumarate) (PPF)-based orthopedic bi omaterial. The effects of varying the PPF to N-vinyl pyrrolidinone rat io and PPF to beta-tricalcium phosphate content were studied. The comp osite mechanical properties and local tissue interactions were analyze d over 12 weeks. An initial increase in both compressive modulus and s trength was seen for composite formulations that incorporated beta-tri calcium phosphate. The samples incorporating a higher PPF to N-vinyl p yrrolidinone ratio reached a maximal compressive strength of 7.7 MPa a nd a maximal compressive modulus of 191.4 MPa at 3 weeks. The lower PP F to N-vinyl pyrrolidinone ratio samples gained a maximum compressive strength of 7.5 MPa initially and a compressive modulus of 134.0 MPa a t 1 week. At 6 weeks, all samples for formulations incorporating beta- tricalcium phosphate crumbled upon removal and were not mechanically t ested. Samples that did not incorporate beta-tricalcium phosphate were very weak and insufficient for bone replacement at the 4-day time poi nt and beyond. Tissue interactions resulted in a mild inflammatory res ponse at the initial time points and mature fibrous encapsulation by 1 2 weeks. (C) 1998 John Wiley & Sons, Inc.