[Composite tissue (bone and ligaments) allografts in the reconstruction of the posterior element of the canine spine (preliminary report)].

Reconstructions of the posterior element of the spine with allograft transplantation in adult mongrel dogs were studied histologically. The bone and ligament composite allografts were frozen at -80 degrees for reduction of the antigenicity. Within four weeks, a new bone formation was observed, and the bony union was completed at 8 weeks after the grafting. The transplanted lamina was replaced by the newly formed bone by creeping substitution within 32 weeks. However a part of the spinous process was absorbed, and was not replaced by new bone. The supraspinal ligament and the ligamentum flavum were gradually replaced by connective tissue resembling a ligament. The scar tissue did not invade into the spinal canal, and symptoms of myelopathy did not appear throughout the observation. Although a biomechanical investigation was not performed, these results indicated reconstruction of the posterior element of the spine with allograft transplantation is possible for clinical application.