Bone formation and static changes in the thoracic spine at uni- or bilateral experimental spondylodesis with...

Bone repair by autografting is an effective but disabling procedure, especially when considerable amounts of transplants are needed, as may be the case in spinal fusion operations. While looking for suitable alternatives, the trend is to study new agents stimulating bone formation (induction) as well as synthetic Bone Matrix (DBM), showing an activation of the osteoinductive properties of a Bone Morphogenetic Protein (BMP), has been successfully used in experimental posterolateral spondylodesis procedures, as it is highly effective together with autogenous Bone Marrow (BM). In the present experiment with thoracal spondylodesis on still growing rabbits, DBM, when supplied alone, confirmed its osteoinductive potential leading to clinical stability within three months in 67% of the cases and total radiological union within five months in all cases. Scoliosis with a rotational component developed following such spondylodesis procedures, but it could not be directly correlated to fusion modalities in the experiment. The pathway's analysis of the amplitude of the spinal canal at the fusion site, when compared to that of the adjacent segments, showed changes as initial increase of the amplitude in the fusion area during early fusion stages, followed by later narrowing. The relation to the amount of implanted DBM in the spondylodesis site and the development of spinal deformities could not be significantly correlated.