Comparison of the biochemical and radiological criteria for lumbar disc degeneration

Abstract

BackgroundThe relationship between radiological degeneration criteria on lumbar magnetic resonance imaging (MRI) and both the keratan sulfate (KS) and chondroitin sulfate (ChS) levels was examined in disc material taken from patients undergoing lumbar disc herniation (LDH) surgery. To examine whether the biochemical and radiological degeneration criteria testing the reliability of radiological degeneration findings agreed and to evaluate the contribution of the KS/ChS ratio to disc form (protruding or extruding). MethodsThis was a prospective experimental cohort study. Using enzyme-linked immunosorbent assay, KS and ChS levels were measured in the degenerate nucleus pulposus taken from 71 patients with a diagnosis of LDH who underwent surgery. The degeneration levels and disc form (protruding or extruding) were determined according to the Pfirrmann five-stage grading system on preoperative T2-weighted lumbar MRIs. According to the Pfirrmann system, 28 patients were grade III and 43 were grade IV. The relationship between radiological criteria and the KS/ChS ratio was statistically evaluated. ResultsThe KS levels (p=0.046) and the KS/ChS ratio (p=0.001) were significantly higher in grade IV patients than in grade III patients. However, there was no difference between the KS and ChS levels and the KS/ChS ratio when patients were classified as protruding or extruding according to their disc structure. Disc structure and biochemical degeneration indicators were not correlated. ConclusionsThe KS level and the KS/ChS ratio were high in patients with marked radiological degeneration on lumbar MRI, demonstrating the sensitivity and reliability of the Pfirrmann five-stage grading system for showing radiological degeneration.