The Experimental Study Of Spindylodiscitis

Objective: To study the mechanism , pathological progress and effects of antibiotics of spindylodiscitis by observing the changes of histology, ultrastructure and the content?of inimunoglobulin, collagen and proteoglycans. Methods: There are together 76 New Zealand adult rabbits, average weight 25kg. 72 rabbits are randomly divided into antibiotics treatment groups and non-treatment group, 6 in each group. Intervertebral discitis model of rabbit is established by injection of staphylococcus aureus into intervertebral disc via retroperitoneum. The intervertebral discs of the rabbits are performed the histopathological examination, the assaying in content of proteoglycans, collagen and immunoglobulin and the ultrastructure observation by scanning electron microscope in 1, 2, 4, 8, 12 and 16 weeks after operation respectively. Another 4 rabbits consist of control group, assaying the normal content of inununoglobin, collagen and proteoglycan. Results: From 1 to 8 week, the intervertebral space of spondylodiscitic rabbits are destroyed seriously. The intervertebral disc space is invaded by inflamniatory cells in microscope. We observe by scanning electron microscope that the chondrocyte-like cells in nucleus pulposus are karyopyknosis, while the organells are destroyed and the lysosomes disappear. The content of collagen and proteoglycans decrease in experimental groups. -4- There is significant difference in the content of collagen and proteoglycans between treated and non-treated groups. The level of immunoglobulin of experimental groups is higher than that of control group., but there is no significant statistical difference between treatment and nontreatment groups. From 8 to 16 week, the intervertebral space of spondylodiscitic rabbit proliferate dominantly, with new bone forming. Scanning electron microscope finds that cartilage-like cells in intervetebral disk increase. The content of collagen and proteoglycans stay at the level of the 8 week, and the level of immunoglobulin return to normal level gradually. In antibiotics treatment groups, the infammation moderates and the content of collagen and proteoglycans is higher than that of non-treatment groups. Conclusion: The spondylodiscitis is not a simple bacterial inflammation. Immunal injury may also play an important role in its pathogenesis. Pathological changes of spondylodiscitis are mainly inflammatory destroy and hyperpasia, destroy of matrix in 1-8 weeks and hyperpasia of connective tissue, formation of new bone in 8-16 weeks. Immunoglobulin, especially IgM, increases abnormally in the process of spondylodiscitis , indicating that spondylodiscitis is related to the immune function of body. The intervertebral disc's collagen and proteoglycans are destroyed in spondylodiscitis, resulting in its physical function deprivation and intervertebral bodies fusing. Antibiotics treatment is effective to spondylodiscitis.