Preliminary report: a ceramic containing crosslinked collagen as a new cranial onlay and inlay material

Simple ceramic bone graft materials have demonstrated significant limitations for use in craniomaxillary reconstruction. We investigated a new, alloplastic composite bone grafting material containing particulate hydroxyapatite and crosslinked collagen in a time-sequence study. Five rabbits underwent surgical placement of high-loading and low-loading composite onlay and inlay grafts in the parietal region of the skull. Animals were sacrificed at either 1, 2, 4, or 6 months postoperatively. All rabbits demonstrated tissue continuity and healing of both onlay and inlay grafts to the outer table of the skull. Bony ingrowth was shown in both onlays and inlays with bone proliferation and vascularization. Bony ingrowth was seen as early as 1 month postoperatively. Inlay grafts healed flush to the outer table, while onlay grafts maintained at least 80% of graft volume at 6 months postoperatively. We conclude that a composite bone grafting material containing a ceramic and collagenous matrix may offer significant advantages to the reconstructive surgeon. The material appears to be easy to handle and carve, is biologically tolerated, and is able to maintain graft volume. Further studies of this new composite material are warranted.