Table 2.

Modified histological IVD degeneration score based on [46] Rutges et al. (2013).

Item and Grade		0	1	2
AF		Normal lamellar pattern	Slight lamellar disorganization	Loss of lamellar organization
AF/NP-border		Normal	Minimal interruption, distinct space/bleb formation between both	Loss of distinction, severe space/bleb formation between both
NP cellularity		Normal cellularity and arrangement	Mild cell density or distribution changes, few cell clusters	Profound cell density/distribution changes, prominent cell clusters
NP ECM distribution		Normal gelatinous appearance	Mild condensation, disorganization	Severe condensation, disorganization
NP morphology	NP shape	Oval	Oval/round, mild distortion	Irregular shape
	NP area	NP constitutes more than 50% of disc area	NP constitutes between 25–50% of disc area	NP constitutes less than 25% of disc area
CEP		No bony sclerosis and regular CEP	Mild bony sclerosis with mildly thickened CEP	Severely thickened CEP with severe sclerosis
Maximal number of points (severe degeneration): 14

AF: annulus fibrosus; CEP: cartilaginous endplate; ECM: extracellular matrix, NP: nucleus pulposus.