Investigation Of Impact Of Spinal Instability On The Epidural Fibrosis And Precaution Of Epidural Fibrosis Postlaminectomy

Objective:To compare whether the stability of spine or not is the important reason for the epidural scar formation and impact of steel instrumentation and free fat transplant on the epidural scar formation postlaminectomy. Method: 128 SD rats were divided into 16 groups randomly; each group has 8 rats, and each rat was performed with total laminectomy of L3. They were steel instrumentation and free fat group(IF), instrumentation group(I), free fat group(F) and control group(C). The rats were sacrificed at the second, forth, sixth and eighth week. Then the gross specimen were observed with Rydell criteria. The measurement of scar area: 128 pathological slices of scar tissues were selected, each group having 8 slices. Then the scar areas were measured by American image-proplus analyzing processor. The measurement scope was that a horizontal line was made from the posterior border of the dura mater. The distance was about half spinal canal anterior-posterior diameter, then the area of scar before the line was measured. The scar area of each slice were added together, then divided by area of intervertebral disc, and the result was the index of scar area. The measurement of fibroblasts and inflammatory cells: the same magnification slice was selected(640x), then the number of the fibroblasts and inflammatory cells was measured by the mouse in the computer. In order to reduce the error, 3 parts of each slice is selected, one in the center and two in the margin. At the same time the measurement was performed by a pathologist who didn't know the process and principle of the experiment. Immunohistochemical method: The CD34 monoclonal antibody was selected as the first antibody, with the immunohistochemical SP procedure, then the pathological slice was displayed by DAB and stained again by hematein. One slice was used as a negative control and reacted with PBS fluid(0.01mmol/L) which was the substitute of anti- CD34.(the kits coming from Boster Biotechnology CO.LTD). The number of the vessels and vascular endothelial cells were displayed by immunohistochemical method. The formation and development of vessels and the early inflammation can be observed at every phase. The measurement of collagen by biochemical method: The scar tissue of 2cm x 2cm was resected in the surgical site and defatted, dehydrated in a dehydrator with 60 centigrade through a total night. Then the specimen was placed in the hydrochloric acid of 6N and hydrolyzed in a pressure steam sterilizer which the pressure was 20 pounds. Then the specimens were totally broken into free amino acids. The hydroxyproline in the specimen reacted with color displaying reagents, and the content of the hydroxyproline was measured. Result: In the gross observation, the extent of scar adhesion in the I group was inferior to the C group at the second and forth week, and there is a statistical difference between the two group(p<0.05). At the eighth week, there was a statistically difference between the IF group and the F group(p<0.05). During two to eight weeks, the scar area in the I group was inferior to the C group. There was also a statistical difference between the two groups(p<0.05).At the second week, the count of fibroblast in the I group was less than the C group(p<0.05). The count of inflammatory cells in the IF group were more than that in the F group at the second week and less than that in the F group at forth and sixth week; the count of inflammatory cells in the I group was less than that in the C group at the forth week; there were all statistical differences between the two groups(p<0.05). There was no statistical differences for the content of collagen between experimental groups and control groups. The count of blood vessels in the I group was less than that in the C group(p<0.05) at the forth week. Conclusion: The spinal instability post-laminectomy may be an important cause for the epidural fibrosis and this may delay the maturity of the fibrosis. The free fat and stable spine can prevent epidural fibrosis obviously in the early period afte...