Transverse process fusion with bovine anorganic bone.

Abstract

A biodegradable collagen membrane and bovine anorganic bone were studied in a rabbit spine fusion model. The bovine, anorganic bone is a nonantigenic, acellular clinical product used as a bone substitute for dento-alveolar applications. We reasoned this product with a collagen membrane could be useful for spine fusions. Our hypothesis was that bovine, anorganic bone, and a collagen membrane would promote spine fusion equivalent to an autogenous bone graft. To test the hypothesis, the transverse processes of the fourth and fifth lumbar vertebrae were decorticated in 30 rabbits divided equally among five groups. In one group, following decortication, no treatment was administered, whereas in the remaining four groups, treatments consisted of either autograft, collagen membrane, anorganic bone, or anorganic bone plus collagen membrane. Rabbits were euthanized 6 weeks after surgery, and the lumbar vertebrae were removed, radiographed, and processed for histology. The radiographs and histological sections were subjected to quantitative morphometric analyses and post hoc statistical testing (p < or = 0.05). We determined anorganic bone without a collagen membrane migrated into the soft tissues contiguous to the transverse processes. However, with a collagen membrane, the anorganic bone remained at the implant site, causing an osseous fusion of the transverse processes. Although the autograft promoted the greatest amount of new bone formation, significant transverse process fusion was accomplished with the anorganic bone and collagen membrane. Additional longer term studies are contemplated to validate feasibility of this clinical option, including a biomechanical component.