Table 1 Definition of a Histological Grading Scale
A. Annulus fibrosus | Grade |
Normal, pattern of fibrocartilage lamellae (U-shaped in the posterior aspect and slightly convex in the anterior aspect) without ruptured fibers and without a serpentine appearance anywhere within the annulus | 1 |
Ruptured or serpentined patterned fibers in less than 30% of the annulus | 2 |
Ruptured or serpentined patterned fibers in more than 30% of the annulus | 3 |
B. Border between the annulus fibrosus and nucleus pulposus | |
 Normal | 1 |
 Minimally interrupted | 2 |
 Moderate / severe interruption | 3 |
C. Cellularity of the nucleus pulposus | |
 Normal cellularity with large vacuoles in the gelatinous structure of the matrix | 1 |
 Slight decrease in the number of cells and fewer vacuoles | 2 |
 Moderate / severe decrease (> 50%) in the number of cells and no vacuoles | 3 |
D. Matrix of the nucleus pulposus | |
 Normal gelatinous appearance | 1 |
 Slight condensation of the extracellular matrix | 2 |
 Moderate / severe condensation of the extracellular matrix | 3 |
E. Pericellular matrix of the nucleus pulposus | |
 Normal | 1 |
 Slight formation of the pericellular matrix | 2 |
 Moderate / severe formation of the pericellular matrix | 3 |