EVALUATION OF A NOVEL MALLEABLE, BIODEGRADABLE OSTEOCONDUCTIVE COMPOSITE IN A RABBIT CRANIAL DEFECT MODEL

The ceramic form of calcium phosphate osteoconductive material such as hydroxyapatite is brittle, non-malleable and non-degradable, and thes e mechanical properties limit its clinical application in calvarium re construction. To improve these properties, we developed a malleable, b iodegradable osteoconductive composite composed of tricalcium phosphat e particles bound by a gelatin which is set by glutaraldehyde mediated cross-linking. The composite was implanted into a 15 X 15 mm full-thi ckness, calvarial defect in 20 rabbits For up to 3 months. Twelve rabb its were left unreconstructed as controls. Specimens were retrieved at 2 weeks, 1, 2 and 3 months. Five reconstructed and 3 unreconstructed rabbits were examined for each time period. The assessment included a series of post operative gross examinations, radiographs and histologi c evaluations. We are able to demonstrate that this composite is ( 1) biocompatible, with little tissue reaction; (2) osteoconductive, with progressive growth of new bone into the calvarial defect; (3) biodegra dable, with progressive replacement of the composite by new bone, a ce llular matrix and bone-like material. Replacement of this composite by new bone is postulated to occur by a combination of osteoconduction a nd biodegradation. These results indicate that further experimental re search to combine this malleable, biodegradable, osteoconductive compo site with an osteoinductive agent such as bone morphogenetic protein m ay generate new biomaterial for full-thickness calvarial defect recons truction. (C) 1998 Elsevier Science S,A, All rights reserved.