Endplate defects, not the severity of spinal stenosis, contribute to low back pain in patients with lumbar spinal stenosis

Background context: It is controversial whether lumbar spinal stenosis (LSS) itself contributes to low back pain (LBP). Lower truncal skeletal muscle mass, spinopelvic malalignment, intervertebral disc degeneration, and endplate abnormalities are thought to be related to LBP. However, whether these factors cause LBP in patients with LSS is unclear.

Purpose: To identify factors associated with LBP in patients with LSS.

Study design/setting: Cross-sectional design.

Patient sample: A total of 260 patients (119 men and 141 women, average age 72.8 years) with neurogenic claudication caused by LSS, as confirmed by magnetic resonance imaging (MRI).

Outcome measures: Ratings of LBP, buttock and leg pain, and numbness on a numerical rating scale (NRS), 36-Item Short Form Survey (SF-36) scores, muscle mass measured by bioelectrical impedance analysis, and radiographic measurements including slippage and lumbopelvic alignment. The severity of LSS, endplate defects, Modic endplate changes, intervertebral disc degeneration, and facet joint osteoarthritis were assessed on MRI.

Methods: The presence of LBP was defined as an NRS score ≥3. The demographic data, patient-reported outcomes, and radiological and MRI findings were compared between patients with and without LBP. Multivariate logistic regression analysis was used to identify the factors that were independently associated with the presence of LBP.

Results: There were significant differences between patients with and without LBP for buttock and leg pain and numbness on the NRS, general health on the SF-36, presence of endplate defects, presence of Modic changes, disc degeneration grading, and disc height grading (all p < .05). Multivariate logistic regression analysis showed significant associations between LBP and diabetes (OR 2.43; 95% CI 1.07-5.53), buttock and leg numbness on the NRS (OR 1.34; 95% CI 1.17-1.52), general health on the SF-36 (OR 0.97; 95% CI 0.95-0.99), and the presence of erosive endplate defects (OR 3.04; 95% CI 1.51-6.11) (all p < .05).

Conclusions: These results suggest that LBP in patients with LSS should be carefully assessed not only for spinal stenosis but also clinical factors and endplate defects.