Lamina repair and replacement to control laminectomy membrane formation in dogs.

This study examined the efficacy of lamina repair by the use of various techniques to prevent postlaminectomy scar formation in a canine system. Five-level noncontiguous laminectomies were performed on six adult canines. The most caudal (Site 1) was left uncovered and served as the control. Exposed dura at each of the remaining four levels was covered with one of the following: Site 2, free autogenous laminar bone graft; Site 3, polymethylmethacrylate; Site 4, Teflon-Proplast composite; Site 5, collagen gel. The dogs used in the study were killed 16 weeks after surgery. Three specimens were examined by plain roentgenography and computerized tomography, two specimens were examined histologically, and the remaining four specimens were graded according to scar volume and scar adherence, as detected during gross dissection of the postlaminectomy scar. No repair technique interfered with roentgenography evaluation. The least scar and fewest adhesions were present under the free bone graft repair site. The Teflon-Proplast composite and polymethylmethacrylate both limited the amount and adherence of scar. Collagen gel and control sites were indistinguishable in this study. It is concluded that lamina repair with a solid material covering exposed dura significantly reduces the formation of postlaminectomy membrane and scar.