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

Study Design. The effectiveness of Polyactive(R) (Osteotech, Inc., Shr ewsbury, NJ), an elastomeric segmental copolymer, as a barrier materia l for the prevention of perineural scar formation was evaluated in eig ht adult mongrel dogs. Two animals each were killed at 2, 4, 8, and 12 weeks postoperation. . This study determined the ability of a Polyact ive(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 laminect omy presents considerable morbidity in lumbar surgery. To date, a wide variety of materials has been evaluated to prevent scar formation inc luding free fat grafts, mechanical barrier devices, hemostatic agents, and anti-inflammatory drugs. However, all studies indicate scar forma tion is present, and the search for an effective barrier continues. Me thods. Gross dissection, radiographic studies, including computed tomo graphy and magnetic resonance imaging, and histologic sections were us ed to evaluate the presence and degree of perineural scarring. If scar ring 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 sc arring; and 3 = extensive scar formation. Results. Polyactive(R) membr anes were an effective barrier with only minimal scar formation to the dura observed at any time period. Free fat graft was an effective bar rier 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 postimplantat ion. Conclusions. The results indicate Polyactive(R) is a reliable and effective means of reducing perineural scar formation. The effectiven ess of the Polyactive(R) membrane could be improved markedly if techni ques or methods to ensure retention of the membrane in the proper posi tion were developed.