Biochemical changes associated with the symptomatic human intervertebral disk.

Significant changes in disk biochemistry were evident in the nuclei pulposi of 25 symptomatic disks that demonstrated abnormal diskography. Compared with the results from ten normal disk from young subjects (mean age, ten years) and from ten asymptomatic disks from adult patients (mean age, 33 years), the symptomatic disks demonstrated significantly greater collagen content than the young and asymptomatic adult subjects, respectively. Significantly fewer total glycosaminoglycans (GAGs) and significantly less water content were also evident for the diseased disks. The mean pH of the nucleus pulposus from 23 patients was also significantly reduced for the symptomatic disks as compared with the mean pH measured for four asymptomatic adult subjects. Although significantly fewer total GAGs were observed for the symptomatic disks, there were no significant differences in the percent composition of hyaluronic acid (HA), chondroitin sulfate (CS), or keratan sulfate (KS) among the normal and symptomatic disks. Significant changes in disk biochemistry are associated with the symptomatic disk, and these changes could contribute to the development of the painful disk syndrome.