Bone grafting and substitutes in spine surgery.

The increase of spinal procedures over the last decades has made the long-term problems, such as pseudarthrosis, apparent. This demands optimized strategies, techniques and technologies. Modern fixation systems have been developed as an adjunct to spinal fusion, and several generations of different synthetic cages have proved to be reasonable alternatives to autologous bone or allografts. The development of recombinant bone morphogenetic proteins (BMPs) is of promise, because of their great osteoinductive capabilities. While spine surgeons are familiar with autologous and synthetic grafts as well as allografts, these comparably new evolving growth-factor-based technologies are of high interest. This was a selective literature review. Alternatives to autologous grafts include allograft bone, synthetic cages and growth-factor based bone substitutes, BMPs being the most-studied among them. Autologous iliac crest alone provides all of the required capabilities of an ideal bone graft, i.e. osteoconduction, osteoinduction, osteogenesis, but each of the alternatives can produce excellent results in a number of indications. If combined, these alternatives can cumulatively provide all required graft capabilities. Nevertheless, all of the available grafts have specific characteristics and can feature certain complications. Alternatives to autologous grafts circumvent donor-site morbidity and are available in a larger amount than autologous bone for extensive surgery. New technologies offer excellent possibilities of new bone formation, but there are also severe risks and high costs to be considered. The indication for bone grafting must be clearly defined, the graft selection should be individually adapted, and the risks, efforts and costs of the selected fusion procedure should be carefully considered.