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[A study on blocking effect of polylactic acid patch on intra-discal inflammation after annulus puncture].

OBJECTIVE
Polylactic acid (PLA) patch has proper steric configuration, sufficient mechanic strength, and flexibility, to investigate the blocking effect on the intra-discal inflammation after annulus puncture sticked by medical glue so as to seal the pinhole left after annulus puncture.


METHODS
Twenty healthy New Zealand white rabbits (weighing 2.0-2.5 kg) were randomly divided into 4 groups (n = 5): groups A, B, C, and D. In group A, the rabbits underwent exposure of intervertebral disc and transverse process at L2-7 as a control; in group B, the rabbits received annulus puncture at L2-7 with an 18-gauge needle; and in groups C and D, the pinholes were sealed respectively with a PLA patch sticked with medical gel and medical gel alone after annulus puncture at L2-7. General condition of rabbits was observed after operation. The intervertebral disc tissue was harvested 1 week after operation. The tissue structure was observed by HE and Masson staining. And the expressions of inflammatory factors like interleukin 1beta (IL-1beta), tumor necrosis factor alpha (TNF-alpha), and inducible nitric oxide synthase (iNOs) were detected with immunohistochemistry and ELISA.


RESULTS
All the animals survived till the end of the experiment. In group A at 1 week, the nucleus pulposus tissue had normal structure. In group B at 1 week, leak of nucleus pulposus from the pinhole and slight adhesion to the adjacent tissue could be seen, and the nucleus pulposus tissue had significant degenerative change by histological observation. In groups C and D, clots of coagulated medical gel and extensive adhesion to the adjacent tissue could be seen; histological observation suggested that the nucleus pulposus tissue of group C had similar histology manifestation to that of group A; while group D had similar histology manifestation to group B with obviously-decreased cells and disorder of matrix. ELISA test showed remarkably elevated expression level of inflammatory factors including IL-1beta, TNF-alpha, and iNOs in groups B and D when compared with groups A and C, showing significant differences (P < 0.05), and similar expression level were observed in groups A and C, groups B and D (P > 0.05).


CONCLUSION
The PLA patch sticked with medical gel is effective in blocking the intra-discal inflammation 1 week after annulus puncture.