THE USE OF EXPANDED POLYTETRAFLUOROETHYLENE AS AN INTERPOSITIONAL MEMBRANE AFTER LUMBAR LAMINECTOMY

Study Design. Prevention of post-laminectomy membrane formation was evaluated in a canine model. Fat graft, Silastic sheeting and expanded polytetrafluoroethylene were compared with nonimplanted control sites. Objectives. The development of an effective barrier to peridural scar invasion is of major importance in optimizing results after lumbar laminectomy. Summary of Background Data. Postoperative peridural fibrosis represents a normal biologic response after lumbar spinal surgery. A variety of biologic and nonbiologic interpositional materials have been studied. Expanded polytetrafluoroethylene has been shown to limit scar adhesion in the pericardium and peritoneum and has not been studied previously as a postlaminectomy interpositional membrane. Methods. Eleven adult female cross-bred hounds underwent multilevel standardized laminotomies. Three materials-fat graft, Silastic sheeting, and expanded polytetrafluoroethylene-were compared with nonimplanted controls. The animals were killed 12 weeks after surgery and were evaluated histologically and using gadolinium-enhanced magnetic resonance imaging. Result. The magnetic resonance imaging studies were inconclusive in assessing peridural scar extension or identifying the implanted membranes. Histology revealed dense scar tissue at all control sites and replacement of all fat grafts by scar. Scar density was significantly less for the expanded polytetrafluoroethylene membrane surgical sites than for the control, fat graft, and Silastic sheeting sites. Conclusions. Expanded polytetrafluoroethylene membrane is biocompatible, maintains its structural integrity, and is impervious to fibrous ingrowth. These findings support further investigation of expanded polytetrafluoroethylene membrane as an interpositional material to prevent post-laminectomy peridural fibrosis.