Table 1. Intervertebral disc histological scores.

Score (mean ± SEM)	Y-Y	Y-O	O-Y	O-O
NP cellularity loss	0.2±0.6	1.1±0.7	0.8±0.8	2.2±0.6
NP clefts/fissures	1.0±0.6	1.3±0.7	1.1±0.6	1.5±0.8
AF/NP boundary	0.7±0.8	0.5±0.5	0.8±0.6	0.7±0.5
AF disorganization	0.4±0.8	1.2±0.7	1.6±0.7	1.4±0.8
AF clefts/fissures	0.0±0.0	0.6±0.7	0.8±0.8	1.2±0.6
Composite score	2.3±1.4	4.7±1.5	5.1±1.6	7.0±1.5