Osteoconductivity of an injectable and bioresorbable poly(propylene glycol-co-fumaric acid) bone cement

We have investigated an injectable form of a resorbable bone cement based o n in situ crosslinking of the unsaturated polyester, poly(propylene glycol- co-fumaric acid) (PPF). This material, filled with calcium gluconate/hydrox yapatite (CG/HA), cures to a hard cement degradable by hydrolysis. The purp ose of this study was to evaluate the osteoconductive properties of this in jectable cement. The cement was used as an adjunct to fixation with an intr amedullary rod in the rat femoral osteotomy model. Ingrowth of new bone int o the cement was examined in vivo. Negative and positive controls with rigi d and loose internal fixation were included for comparison. Animals were ev aluated histologically and histomorphometrically at 4 weeks postoperatively . Results of this study showed osteoblastic activity and new bone formation at the interface between the femoral bone and the cement in the experiment al group. However, there was little bone remodeling at the endosteal surfac e in positive and negative controls. Histologic evaluation of the cement re vealed the formation of cavitations, which likely resulted from leaching of the highly soluble calcium gluconate portion of the filler from the cement . These cavitations were sites of ingrowth of vascular and bony tissues. In timate contact between the bone cement and the endosteal surface of the cor tex was found. Quantitative histomorphometric analysis corroborated these o bservations. Findings of this study demonstrated the osteoconductivity of t his type of injectable PPF-based bone cement. (C) 1999 Elsevier Science Ltd . All rights reserved.