BIOCHEMICAL FEATURES OF RECURRENT HERNIAS OF THE LUMBAR INTERVERTEBRAL DISCS AT DIFFERENT STAGES OF THEIR DEGENERATION

Abstract

Objective. To study biochemical changes in proteoglycans (PGs) of intervertebral disc tissues and stages of their degeneration in patients with recurrent disc herniation. Material and Methods. A retrospective analysis of biochemical and radiological parameters of primary hernias of intervertebral discs from 16 patients who were reoperated on at the same level within three years was performed. Degenerated discs were classified according to the Pfirrmann’s criteria. The quantity of glycosaminoglycans (GAGs) in the hernia and surrounding annulus fibrosus tissues was determined by analytical biochemistry methods. The properties of PG in the hernia tissue were studied using composite gel electrophoresis. Results. Two types of primary hernias were identified. The tissues of Type 1 hernias were characterized by high content of water, total GAG, and PG. But the number of GAGs lying in the deeper layers of tissue is extremely low. The tissues of Type 2 hernias showed reduced water content, GAG number, degree of their sulfation, and increased content of neutral hexoses. These hernias contain a large proportion of non-aggregated PGs and more than half of all GAGs are found in deeper layers of tissue. On MRI evidence Type 1 hernias corresponds to Grade III degeneration, and Type 2 - to Grade IV. Grade III degeneration predominates among the hernias, which recurrent within the first year after surgery. Conclusion. The structure of tissue of primary disc hernias recurring after surgical removal demonstrates regular biochemical changes in PGs and GAGs, which are registered by MRI with different signal intensity. Hir. Pozvonoc. 2012;(2):87-93.