Association between Annular Tears and Disk Degeneration: A Longitudinal Study

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Fig 1.
The signal-intensity grading scale. Grade 1 (A) implies a normal disk with preserved signal intensity in the central aspect. Grades 2–5 (B–E) represent disks with areas of signal-intensity loss affecting <25%, 26%–50%, 51%–75%, and 76%–99% of the central disk volume. No appreciable central hyperintensity is noted in Grade 6 (F). All images extending through the disk were taken into consideration at the time of assigning the signal intensity grade.
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Fig 2.
Natural progression of disk degeneration of the L2–3 intervertebral disk during a 24-month period. A, The L2–3 disk shows grade 2 signal intensity and grade 2 degeneration on the sagittal T2-weighted turbo spin-echo image from the initial lumbar spine MR imaging. B, A right foraminal and extraforaminal grade 2 annular tear is noted at the L2–3 level (arrow). C, Follow-up MR imaging performed 24 months later demonstrates interval loss of signal intensity and disk height at the L2–3 level, which was graded 4 on both signal-intensity and degeneration scales. Note the relative stability of the L1–2 disk on 2 MR imaging examinations.

Table 1:

Mean (±SD) initial signal-intensity and degeneration grades and changes in them by annular tear for all disks and by disk level

Disk	Annular Tear?	Initial Signal-Intensity Grade	Initial Degeneration Grade	Change in Signal Intensity	Change in Degeneration
All	No	1.43 ± 0.62	2.20 ± 0.40	0.15 ± 0.54	0.15 ± 0.39
	Yes	3.07 ± 1.31	3.24 ± 0.94	0.42 ± 0.85	0.31 ± 0.37
T12-L1	No	1.50 ± 0.50	2.19 ± 0.40	0.11 ± 0.43	0.23 ± 0.42
	Yes	2.60 ± 1.42	2.90 ± 1.02	0.40 ± 0.88	0.30 ± 0.57
L1–2	No	1.27 ± 0.57	2.22 ± 0.43	0.27 ± 0.43	0.05 ± 0.23
	Yes	2.87 ± 1.2	3.14 ± 0.93	0.46 ± 0.79	0.25 ± 0.51
L2–3	No	1.53 ± 0.90	2.20 ± 0.41	0.06 ± 0.70	0.13 ± 0.56
	Yes	2.90 ± 1.16	3.16 ± 1.00	0.38 ± 0.80	0.32 ± 0.59
L3–4	No	1.50 ± 0.52	2.30 ± 0.48	0.20 ± 0.63	0.10 ± 0.41
	Yes	3.25 ± 1.33	3.30 ± 0.85	0.33 ± 0.92	0.41 ± 0.55
L4–5	No	1.00 ± 0.00	2.00 ± 0.00	0.50 ± 0.70	0.50 ± 0.72
	Yes	3.25 ± 1.31	3.36 ± 0.96	0.40 ± 0.87	0.25 ± 0.57
L5-S1	No	1.50 ± 0.70	2.00 ± 0.00	-0.50 ± 0.90	0.00 ± 0.00
	Yes	3.22 ± 1.37	3.34 ± 0.91	0.56 ± 0.87	0.34 ± 0.64

Table 2:

Results of mixed-model analysis of signal-intensity grade and degeneration grade

	Initial Signal-Intensity Grade	Initial Degeneration Grade	Change in Signal Intensity	Change in Degeneration
Disk	P = .003	P = 0.002	P < .0001	P < .0001
Initial annular tear	P < .0001	P < .0001	P < .0001	P < .0001
Stage	–	–	P < .0001	P < .0001
Time between studies	–	–	P = 0.98	P = .70

Patient was treated as a random effect, and disk and presence of an annular tear on initial MR imaging were treated as fixed effects on all the analyses. Initial signal-intensity and degeneration grades were used as the dependent variables to analyze patterns at baseline. Signal-intensity grade and degeneration grade for both stages (initial, follow-up) were the dependent variables, and stage was added as a fixed effect, to analyze change, as was the time between studies, to control for differences between patients.

Table 3:

Distribution of signal-intensity grades and annular tears on initial MR imaging

Table 4:

Distribution of degeneration grades and annular tears on initial MR imaging