Table 3.

Classification of macroscopic patho-anatomic changes associated with disk degeneration according to Nachemson [17]

Degenerative disk disease assessed by macroscopic inspection
Grade of degeneration
A	Disks without changes visible to the naked eye. In these cases a gelatinous shiny nucleus pulposus was seen; it was easily delimited from the anulus fibrosus, which was free from macroscopic ruptures
B	Disks which showed macroscopic changes in the nucleus pulposus. The nucleus was somewhat more fibrous, but could be clearly distinguished from the annulus, which was intact
C	Specimens which showed macroscopic changes in both the nucleus pulposus and the annulus fibrosus. The nucleus in these discs was more fibrotic but still soft. The boundary between nucleus and and annulus was no longer so distinct, but could be seen. Changes in the annulus fibrosus consisted of isolated fissures
D	Specimens which showed more severe macroscopic changes. The disk in this group exhibited fissure formation and cavities in both the nucleus and the annulus. Marginal osteophytes were often found in adjoining vertebrae