Experimental application of a biomaterial in bifocal transport osteogenesis for craniofacial reconstruction

Abstract

Bifocal transport osteogenesis is an alternative technique of callus distraction, in which movement of a transport segment results in the formation of new bone in order to close a continuity defect. The aim of this experimental pilot study was to replace a bone graft by a biomaterial as a transport segment. Critical size defects of the calvaria in four adult sheep were treated with transport segments consisting either of an autogenous free bone graft of the calvaria (n=2) or of the biomaterial (deproteinized bovine cancellous bone; n=2). Latency period was 5 days; the rate of distraction was 1mm per day and was planned for 40 days. The consolidation period was 28 days. Specimens were investigated by conventional radiography, CT-scans and histologically, including immunofluorescence. In both groups, transport osteogenesis resulted in a "de novo" formation of bone, indicating that this biomaterial may contribute successfully to bone formation in bifocal transport osteogenesis. However, volume and thickness of the newly formed bone at the defect site were smaller when using the biomaterial than when using autogenous bone grafts. The application of a biomaterial as transport segments in bifocal transport osteogenesis in cranial critical size defects resulted in the formation of new bone thus excluding bone graft donor site morbidity.