The fate of autogenous grafts to the spinal dura

Abstract

✓ An experimental study was designed to compare the efficacy of autogenous fat and Gelfoam in minimizing scar tissue attachment to the dura and nerve roots. A multiple level lumbar laminectomy was performed in 20 dogs, and Gelfoam and autogenous fat were placed in the epidural space at two laminectomy sites, over the dura, interposed between the overlying paraspinal muscles and the dura. A third lumbar laminectomy site in each dog served as a control. The animals were sacrificed after different time periods (3, 6, 12, 18, and 24 weeks), and the specimens were examined histologically and histochemically. The colloidal iron-periodic acid Schiff-Bismarck brown-picric acid (CI-PAS-BB-PA) and high iron diamine-Alcian blue 8Gx (HID-AB) techniques were used to demonstrate connective tissues and glycosaminoglycans. The scar at the laminectomy sites where Gelfoam was placed and at the control sites was composed of dense irregular connective tissue. Examination of the laminectomy sites where autogenous fat was used revealed less scar tissue. In addition, there was a layer of fat with a slight increase in intercellular connective tissue fibers interposed between the overlying erector spinae musculature and the dura. Our results indicate that autogenous fat interposed between the dura and the overlying paraspinal musculature serves as a barrier limiting the growth of connective tissue into the spinal canal. We could find no evidence that Gelfoam prevented the ingrowth of scar tissue into the operated area.