Prevention Of Epidural Fibrosis And Adhesions With Oxiplex/SP Gel And Radiation After Laminectomy In Rats

Objective: to evaluate the role of Oxiplex/SP gel and radiation in prevention of epidural fibrosis formation following laminectomy in rats by observing the morphological changes. we also can compare this kind of gel with sodium hyaluronate which was known as efficient material publicly to assess the safety and efficacy parameters of Oxiplex/SP gel (CMC/PEO). Materal and methods: twenty-eight SD rats were used as the animal model in this study.They were divided to two groups: group A and group B,each were forteen rats.In group A,all rats underwent bilateral lumbar laminectomy about 0.5×1.0cm area in lumber 1,3and5, epidural fat was removed and the dura was exposed, the laminectomy sites were implanted with sodium hyaluronate and Oxiplex/SP gel at a randomly assigned level, the other laminectomy site as controll. In group B, each rat receive exteral beam radiation in a single fraction of 500cGy in lumber 5 section 24 hours before surgery, the isodose distribution was such that the dose conform to the posterior epidural space about 3×3cm area with minial exit dose to normal tissue. In the same way, bilateral lumbar laminectomy in lumber 5and3 was performed with dura exposed extendly,the remaining L3 level serving as control. At 2,4,8 week after surgery, the rats were killed and histologic sections prepared from the spines were examined and graded for both the control and experimental sites by a pathologist. At 4 week after surgery, we also took little epidural scar tissue for electron microscope observing. The statistical software(SAS) was employed to perform all statistical comparisons. Results: In the control group,adhesion of the exposed dura was apparent. Thick, fibrous connective tissue was observed between the dura and the paravertebral muscles. In the sodium hyaluronate group, the dura was seprated from the scar tissue by the gel, however that a few epidural scar adhered to dura and fibroblasts migrated into the interstitial space can be seen. In Oxiplex/SP gel group, few scar tissue existed in epidural space, only a thin synovium-like layer formed around dura.Compared to control site, Oxiplex/SP gel significantly reduced the formation of epidural fibrosis and its area of contact with the dura postlaminectomy, significent difference in efficacy was detected. Statistical comparison between the Oxiplex/SP gel and the control sites using the Signed Rank Test revealed these differences to be highly significent:P<0.01.In the other way, comparison between the Oxiplex/SP gel and sodium hyaluronate also revealed apparent difference:P<0.05, so the former is superior to the latter in preventing epidural fibrosis formation.In group B,the control sites revealed large and dense fibrotic scar tissue that filled the laminectomy site and was typically tethered...