RESUMEN
STUDY DESIGN: In vivo study OBJECTIVES: To evaluate variations in matrix metalloproteinase (MMP) expression levels according to the disc location in patients with sequestrated lumbar disc herniation. SUMMARY OF LITERATURE REVIEW: MMPs are considered to be the major catabolic enzymes in the intervertebral disc. MMPs have been known to be the primary mediators of extracellular matrix (ECM) degradation, to play major roles in disc degeneration by changing the collagens and the extracellular matrix, and to be involved in the processes of apoptosis and autoresorption of herniated disc materials by inducing inflammatory cytokines. MATERIALS AND METHODS: The sequestered and contained disc materials were removed from seven patients with sequestered lumbar disc herniations. The materials from the contained discs were classified into group 1 and those of the sequestered discs into group 2. Immunochemistry tests were conducted for the tissues of both groups. The expression levels of MMP-1, 3, and 13 were checked using a fluorescence microscope. The amount of expression of each MMP was calculated using the percentage of expressed cells and analyzed statistically. RESULTS: In the histological study, increased expression of MMP-1, 3, and 13 was found in group 2. In the statistical analysis after the quantification of MMP expression, the expression of all MMPs was found to have increased significantly in group 2 (p<0.05). CONCLUSIONS: The increased expression of MMP-1, 3, and 13 indicated that the inflammation and degeneration processes, and the spontaneous resorption by the surrounding tissues were more active in the sequestered disc group than in the contained disc group.