Table 3.

Macroscopic grading system for lumbar intervertebral disc degeneration used as the “gold standard” to define the “real” degree of degeneration (modified according to the systems found in literature)

Macroscopic grading system for lumbar intervertebral disc degeneration (based on mid-sagittal sections)
Nucleus pulposus		Annulus fibrosus	Endplate cartilage
Appearance		Appearance	Sum of points of both cartilaginous endplates Normal: 0 points Thickness irregular: 1 point Focal defect(s): 2 points (Almost) complete destruction: 3 points
0=Bulging gel 1=Fibrous tissue; loss of annular-nuclear demarcation 2=Focal clefts 3=Complete disruption of nucleus or complete transformation into tissue other than nucleus tissue		0=Discrete fibrous lamellas 1=Mucinous infiltration 2=Focal disruptions 3=Complete disruption of anterior plus posterior annulus or complete transformation into tissue other than annulus tissue	0=0 points 1=1–2 points 2=3–4 points 3=5–6 points

Height loss	Osteophyte formation	Diffuse sclerosis	Overall degree of degeneration
Anterior and posterior height loss with respect to the individual height before degeneration	Sum of points of four edges No osteophytes: 0 points <3 mm: 1 point ≥3 mm but <6 mm: 2 points ≥6 mm: 3 points	Sum of points of both adjacent vertebral bodies No sclerosis: 0 points 0.25 partially or completely affected: 1 point 0.5 partially or completely affected: 2 points >0.5 partially or completely affected: 3 points	Sum of points of “Nucleus Pulposus”, “Annulus Fibrosus”, “Endplate Cartilage”, “Height Loss”, “Osteophyte Formation” and “Diffuse Sclerosis”
0=0% 1=<33% 2=≥33 but <66% 3=≥66%	0=0 points 1=1–4 points 2=5–8 points 3=9–12 points	0=0 points 1=1–2 points 2=3–4 points 3=5–6 points	0 point = grade 0 (no degeneration) 1–6 points = grade 1 (mild degeneration) 7–12 points = grade 2 (moderate degeneration) 13–18 points = grade 3 (severe degeneration)

The six variables “Nucleus Pulposus”, “Annulus Fibrosus”, “Endplate Cartilage”, “Height Loss”, “Osteophyte Formation” and “Diffuse Sclerosis” are first graded individually on a scale from 0 to 3. The “Overall Degree of Degeneration” is then assigned according to the sum of these six scores. Note that the macroscopic and the radiographic grading system are almost identical for the three variables, namely, “Height Loss”, “Osteophyte Formation” and “Diffuse Sclerosis”