Craniofacial osseous restoration with osteoinductive proteins in a collagenous delivery system.

Implants fabricated from mixtures of extracted bovine bone proteins and highly purified human type I collagen have been tested for efficacy in the restoration of osseous defects. Experimental implants composed of osteoinductive proteins and collagen, and control implants composed of collagen alone were placed in 15 x 15 mm cranial defects in New Zealand white rabbits. Implants harvested at 10, 12 and 14 week intervals were subjected to histological evaluation as well as quantitative analysis utilizing a computer morphometric planimeter. Defects filled with control implants displayed highly variable repair with a mean of 31% bony healing. Experimental implants were consistently effective in inducing significant bony regeneration with a mean of 91% repair within the time range of the study. In light of these results, it is apparent that an osteoinductive-collagenous implant system represents an efficacious treatment modality in osseous reconstruction and augmentation.

A review of matrix-induced osteogenesis with special reference to its potential use in cranio-facial surgery.

Current data suggests that purified osteoinductive protein packaged into a collagenous delivery vehicle represents a viable alternative to restoring osseous defects with conventional implant materials. The proteins responsible for matrix-induced osteogenesis are the same as those that initiate and complete osseous repair of fractures. Consequently, the process of matrix-induced osteogenesis produced by implantation of the osteoinductive protein mimics the naturally occurring phenomenon of reparative osteogenesis. The collagenous delivery vehicle apparently serves the same role as the inactive collagenous bone matrix which is left after removal of the osteoinductive proteins from demineralized bone and, is required if osteogenesis is to occur. This collagenous delivery vehicle apparently serves a scaffold for the migration into, proliferation, and subsequent differentiation of cells responsible for osteogenesis. In addition, the original form of the collagenous implant dictates the dimensions of the resulting bony tissue. Finally, it is possible to generate an osteoinductive response in many mammals probably including man with purified xenogenic osteoinductive proteins. In conclusion, there is currently much research investigating the phenomenon of matrix-induced osteogenesis and its potential clinical use. In the past few years, there has been a sharp increase in the number of manuscripts published in this area of connective tissue research. Consequently, if the current trend continues, clinicians in the near future can look forward to seeing this material being developed into a convenient "off the shelf" bone replacement system which stimulates host bone formation and repair of cranio-facial osseous defects.

Packaging and delivery of bone induction factors in a collagenous implant.

Extracts of demineralized rat bones which contained factors stimulating bone induction were reconstituted with highly purified human type I collagen to provide a suitable and easily manipulated delivery system for surgical implantation. When implanted subcutaneously in rats, the implants governed and delineated the dimensions of the resulting bony tissue. It is proposed that this implant system has clinical application in the filling of osseous defects within the scope of orthopaedic and oral and maxillofacial surgery. It is presented here as a potential improvement over conventional implant materials without osteoinductive properties.