Effectiveness Of Different Epidural Coverage Materials For Preventing Postoperative Scar Hyperplasia And Dural Adhesion In Spine

Aims: To analyze the effects and mechanisms of three commonly used epidural overlays,gelatin sponge,bovine Achilles tendon extracted collagen and polyester urethane fiber,in preventing epidural scar adhesion after laminectomy in rats.Methods: Forty-eight adult Wistar rats were excised from L2 to 5 lamina to make laminectomy models,and randomly divided into four groups according to different covering materials: blank group（group A）,gelatin sponge group（absorbable,group B）,polyester urethane fiber group（non-absorbable,group C）and bovine Achilles tendon extract collagen group（absorbable,group D）.At 4 and 12 weeks postoperatively,the spinal tissues of the operated area were taken for gross observation（Rydell scar adhesion rating criteria）and histological observation（Nussbaum criteria）;and the expression of three scar proliferation-related cytokines,basic fibroblast growth factor（b FGF）,growth transforming factor β1（TGF-β1）and vascular endothelial growth factor（VEGF）,were measured in the peridural tissues.The differences between the indices in each group were analyzed and compared.Results: All 48 rats survived,and gross and histological findings at 4 and 12 weeks showed no dural adhesions in the gelatin sponge and bovine Achilles tendon extract collagen groups,adhesions in the polyester urethane fiber group,and heavy adhesions and spinal cord compression in the blank control group.The Rydell ratings [M（Q1,Q3）]were 2.50（2.00,3.00）,0（0,1.00）,1.00（1.00,2.00）,0（0,0.50）（P<0.01）at 4 weeks and2.00（1.00,2.50）,0（0,0.50）,0.50（0,1.00）,0（0,0.50）（P<0.01）at 12 weeks for the blank group,gelatin sponge group,polyester urethane fiber group,and bovine Achilles tendon extract collagen group,respectively;the Nussbaum ratings were 3.00（3.00,3.00）,1.00（0.50,1.50）,3.00（2.00,3.00）,1.00（0.00,1.50）（P<0.01）at 4 weeks and3.00（2.50,3.00）,0（0,1.00）,2.00（1.00,2.00）,0（0,1.00）（P<0.01）at 12 weeks,respectively.Western protein blotting at 4 and 12 weeks confirmed that the expression levels of three cytokines,including b FGF,TGF-β1,and VEGF,were lower in the absorbable material group than in the non-absorbable group,with statistically significant differences（all P<0.01）.Immunofluorescence tests at 12 weeks confirmed that the absorbance values of b FGF,TGF-β1,and VEGF were lower in the gelatin sponge group（9.81±0.81,12.42±2.35,8.63±1.76）and the bovine Achilles tendon extract collagen group（12.70±2.02,8.23±1.03,10.19±2.67）than in the polyester urethane fiber group（33.94± 2.03,30.29±2.76,25.79±1.21）,and the differences between groups were statistically significant（all P<0.01）.Conclusion: The extraction of collagen and gelfoam by bovine Achilles tendon can effectively reduce the postoperative scar hypertrophy and hard spinal membrane adhesion in the spine.