The association of combination of disc degeneration, end plate signal change, and Schmorl node with low back pain in a large population study: the Wakayama Spine Study

Abstract Background context Disc degeneration (DD) reportedly causes low back pain (LBP) and is often observed concomitantly with end plate signal change (ESC) and/or Schmorl node (SN) on magnetic resonance imaging. Purpose The purpose of this study was to examine the association between DD and LBP, considering ESC and/or SN presence, in a large population study. Study design/setting Cross-sectional population-based study in two regions of Japan. Patient sample Of 1,011 possible participants, data from 975 participants (324 men, 651 women; mean age, 66.4 years; range, 21–97 years) were included. Outcome measures Prevalence of DD, ESC, and SN alone and in combination in the lumbar region and the association of these prevalence levels with LBP. Methods Sagittal T2-weighted images were used to assess the intervertebral spaces between L1–L2 and L5–S1. Disc degeneration was classified using the Pfirrmann classification system (grades 4 and 5 indicated degeneration); ESC was defined as a diffuse high signal change along either area of the end plate, and SN was defined as a small well-defined herniation pit with a surrounding wall of hypointense signal. Logistic regression analysis was used to determine the odds ratios (ORs) and confidence intervals (CIs) for LBP in the presence of radiographic changes in the lumbar region and at each lumbar intervertebral level, compared with patients without radiographic change, after adjusting for age, body mass index, and sex. Results The prevalence of lumbar structural findings was as follows: DD alone, 30.4%; ESC alone, 0.8%; SN alone, 1.5%; DD and ESC, 26.6%; DD and SN, 12.3%; and DD, ESC, and SN, 19.1%. These lumbar structural findings were significantly associated with LBP in the lumbar region overall, as follows: DD, ESC, and SN, OR 2.17, 95% CI 1.2–3.9; L1–L2, OR 6.00, 95% CI 1.9–26.6; L4–L5, OR 2.56, 95% CI 1.4–4.9; and L5–S1, OR 2.81, 95% CI 1.1–2.3. The combination of DD and ESC was significantly associated with LBP as follows: L3–L4, OR 2.43, 95% CI 1.5–4.0; L4–L5, OR 1.82, 95% CI 1.2–2.8; and L5–S1, OR 1.60, 95% CI 1.1–2.3. Conclusions Our data suggest that DD alone is not associated with LBP. By contrast, the combination of DD and ESC was highly associated with LBP.