[The scar tissue protective effect of free autologous fatty tissue transplants. An animal experiment on spinal surgery].

All spinal operations can be followed by the formation of extensive epidural scar tissue. The development of fibrous adhesions around the nerve roots is known to be the main cause of recurrent symptoms after lumbar discectomy. In the past many materials have been used to prevent or to reduce postlaminectomy membrane, with very different results. They have to be implanted onto the dura at the end of the operation. Therefore, we carried out the following controlled experimental study in dogs to compare the materials that seemed to be most suitable. In 30 adult beagles three lumbar laminectomies were performed. For each level a different material was used--free autologous fat graft, cellulose mesh, gel foam, triamcinolone suspension. Animals were sacrificed after 7 days and 1, 3, and 6 months. The lumbar vertebral columns were prepared for further histological examination. We found that free autologous fat grafts reduce epidural scarring in a high percentage, especially after 3 and 6 months. Only in this group good or excellent results were found at all lumbar levels (n = 18). To compare the results with each other we used a newly developed classification scheme (I-IV). The consistency and extent of scar tissue, the kind of cellular infiltrations, and adhesions to the surrounding structures were estimated separately. Cellulose mesh yielded the worst results. We conclude that free autologous fat is superior to other materials, because of: (1) simple and uncomplicated operative handling, (2) good compatibility and (3) effective prevention of postlaminectomy membrane.