REDUCTION IN PERINEURAL SCAR FORMATION AFTER LAMINECTOMY WITH POLYACTIVE(R) MEMBRANE SHEETS

Study Design. The effectiveness of Polyactive(R) (Osteotech, Inc., Shrewsbury, NJ), an elastomeric segmental copolymer, as a barrier material for the prevention of perineural scar formation was evaluated in eight adult mongrel dogs. Two animals each were killed at 2, 4, 8, and 12 weeks postoperation. . This study determined the ability of a Polyactive(R) membrane to prevent perineural scar and compared the results to those obtained using free fat graft and nonimplanted control subjects. Summary of Background Data. Perineural scar formation after laminectomy presents considerable morbidity in lumbar surgery. To date, a wide variety of materials has been evaluated to prevent scar formation including free fat grafts, mechanical barrier devices, hemostatic agents, and anti-inflammatory drugs. However, all studies indicate scar formation is present, and the search for an effective barrier continues. Methods. Gross dissection, radiographic studies, including computed tomography and magnetic resonance imaging, and histologic sections were used to evaluate the presence and degree of perineural scarring. If scarring was evident in each of the evaluations, the degree was graded on a 0-3 scale where: 0 = no scarring; 1 = mild scarring; 2 = moderate scarring; and 3 = extensive scar formation. Results. Polyactive(R) membranes were an effective barrier with only minimal scar formation to the dura observed at any time period. Free fat graft was an effective barrier to scar formation at early time periods; however, progressive fat graft degradation with some increased scarring was observed at latter time periods. Nonimplanted control defect sites resulted in moderate to severe scar formation to the dura as early as 2 weeks postimplantation. Conclusions. The results indicate Polyactive(R) is a reliable and effective means of reducing perineural scar formation. The effectiveness of the Polyactive(R) membrane could be improved markedly if techniques or methods to ensure retention of the membrane in the proper position were developed.