A HISTOLOGICAL STUDY ON POLYACTIVE(R) FOR THE PREVENTION OF PERIDURALADHESIONS AFTER SPINAL SURGERY - AN EXPERIMENTAL-STUDY IN DOGS WITH A3 MONTHS FOLLOW-UP

In the present study the potential of Polyactive(R) bilayer sheets in the prevention of scar tissue formation after spinal surgery was inves tigated. Eight adult beagle dogs underwent 3 laminectomies at three le vels (L2, L4 and L6). According to a randomized implantation schedule a Polyactive(R) sheet or autogenous fat graft was placed in the defect . The third site served as a control without implant. After 4 or 12 we eks (4 dogs per period) the dogs were sacrificed and histological sect ions were prepared. The Polyactive(R) treated defects showed partial c losure by newly formed bone. The Polyactive(R) was encapsuled by a thi n fibrous tissue layer. Ventral to the defect, dense fibrous tissue wa s present which was separated from the dura by the Polyactive(R) sheet in all cases. In some cases fibrous tissue was present between the im plant capsule and the dura. In the fat graft group there were no signs of closure of the defect but most sites showed fibrous tissue at the edges of the graft, which was in 4 sites continuous with the dura mate r. Fibrosis and degeneration of the fat grafts were seen. All control defects showed partial closure by newly formed bone, and ventral to th e defect extensive fibrous tissue, which was in 50% continuous with th e dura mater. Other sections showed loose connective tissue in contact with the dura mater. It is concluded that Polyactive(R) has a potenti al as a mechanical barrier in the prevention of adhesions between the dorsal spinal muscles and the dura mater.