Heparinized materials for control of the formation of the laminectomy membrane in experimental laminectomies in dogs.

This study examined the efficacy of heparinized biodegradable materials in the prevention of post-laminectomy scar formation using a canine system. Six-level noncontiguous laminectomies were performed on five adult canines. Exposed dura at each level was covered with the following: (1) nothing (control); (2) fat; (3) fat and autogeneic bone; (4) heparinized Avitene; (5) heparinized Surgicel; or (6) heparinized collagen gel. Canines were killed 16 weeks postoperatively and histologic specimens examined. Fibrous adhesions were abundant at Site 1 (control). Free fat grafts were well preserved and did not permit adhesions at Sites 2 and 3. None of the heparinized materials was as effective as fat in controlling scar formation. Overlying bone at Site 3 did not alter the quality of a free fat graft placed over the dura, a point possibly significant for laminectomies followed by fusion.