Experimental Study Of Using Absorbable PLGA Membrane For Preventing Epidural Adhesion After Laminectomy

Objective We want to approach the mechanisms and function of absorbable PLGA membrane in prevention of epidural scar adhesions after laminectomy.Methods All the 48 rabbits were equally divided into three groups by chance,so each group had 16 rabbits,Group A is normal saline group;Group B is gelatin sponge group;Group C is PLGA membrane group.Laminectomy was performed on the 5th lumbar segment,The duramater(8mm×4mm)was exposed,and explored the nerve roots,ln Group A:the exposed duramater was no management; In Group B:covered with gelatin sponge(10mm×5mm);and in Group C:covered with absorbable PLGA membrane(10mm×5mm).Sacrificed 4 rabbits every group at 2,4,6 and 8 weeks,harvested L5 level samples.The specimens were then:Observed grossly,to grade according to Rydell scar adhesions level scoring standard.After stained with HE,we observed the specimens under light microscope, scored them according to modified Nussbaum standard,counted fibroblasts unit area.Cut the scar tissue of every group for observing under transmission electron microscope.Rydell scoring,modified Nussbaum scoring and fibroblasts counting results were analyzed by statistics,letα＜0.05 as the standard of significant difference.Results All the 48 rabbits were available for analysis.①Gross observation:The epidural scar formation and adhesion become more obvious with time prolong in Group A and Group B. In Group A,we can see spinal duramater adheres extensively with epidural fibra scar at 4,6 and 8 weeks.At the 2^thweek epidural adhesion was observed in Group B,at the 4^thweek after operation the gelatin sponge was absorbed completely,extensive fibra scar adhesion could be observed at 6 and 8 weeks.In Group C,the PLGA membrane was almost fully degraded at the 8^thweek post operation, and the surface of epidural was smooth without obvious thickening, just with little or no libra scar adhesion.②Histological observation:On the surface of the epidural there were lots of fibroblasts and inflammatory cells in Group A and B at 4,6 and 8 weeks post operation,spinal dura mater adhered extensively with epidural fibra scar.But in Group C,the situation was different,we didn't see epidural fibrous tissue formation, fibroblasts was less than Group A and B,inflammatory cells have no different with Group A and B,duramater didn't adhere with dorsotissue either.③Electron microscopic observation:Lots of collagen fiber which lined up in order was observed in Group A and B,with loose nuclear chromatin,abundant cytoplasm,enriched mitochondrion and rough endoplasmic reticulum.The situation was different in Group C,there were a few indiscriminate collagen fiber,very few fibrocytes and fibroblasts,with little collagen fiber around.Fibroblasts had almost become fibrocystic:had condensed nuclear,staining deeply,little cytoplasm and few organelles.④Statistical analysis with SPSS13.0 found that there were significant deviation between Group A and C(P＜0.05), significant deviation between Group B and C(P＜0.05),but no significant deviation between Group A and B(P＞0.05).Conclusion In this experiment we use gelatin sponge and PLGA membrane to prevent epidural adhesion after laminectomy.Through the study we found that:(1)The PLGA membrane is an ideal material which can be used to prevent adhesion:It reduces postoperational formation of epidural fibrous scar and newly formed bone;also it can reduce the adhesion between scar and duramater.(2)Gelatin sponge isn't a suitable material for prevention of adhesion,for it isn't good enough to prevent epidural adhesions.