The Relationship Between Endplate Pathology and Patient-reported Symptoms for Chronic Low Back Pain Depends on Lumbar Paraspinal Muscle Quality

Abstract

Study design: Cross-sectional cohort study of chronic low back pain (CLBP) patients and matched controls.

Objective: To explore the interplay between vertebral endplate damage and adjacent paraspinal muscle (PSM) quality, and to test their association in a cohort of patients with CLBP and matched controls.

Summary of background data: Nonspecific CLBP is challenging to diagnose, in part, due to uncertainty regarding the source of pain. Delineating interactions among potential CLBP mechanisms may enhance diagnosis and treatment customization.

Methods: We collected advanced MRI imaging on 52 adult subjects, including 38 CLBP patients and 14 age- and sex-matched asymptomatic control subjects. Mean multifidus and erector spinae fat fraction (FF) was measured throughout the spine using an IDEAL MRI sequence. Presence of cartilage endplate (CEP) defects was determined at each disc level using UTE MRI. Logistic regression was used to test association of PSM FF, CEP defects, modic changes (MC), disc degeneration, and their interplay.

Results: We observed that CEP defects were the strongest predictor of nonspecific CLBP (OR: 14.1, P < 0.01) even after adjusting for MC and disc degeneration (OR: 26.1, P = 0.04). PSM quality did not independently distinguish patient and control groups, except for patients with high self-reported disability.At specifically L4L5, CEP damage was most prevalent and CEP damage was significantly associated with CLBP (OR: 3.7, 95% CI: 1.2-21.5, P = 0.03). CEP damage at L4L5 was predictive of CLBP when adjacent to PSMs with greater FF (MF, OR 14.7, P = 0.04; ES, OR: 17.3, P = 0.03), but not when PSM FF was lower and comparable to values in control, asymptomatic subjects.

Conclusion: These results demonstrate the clinically important reciprocity between passive and dynamic spinal stabilizers, and support the notion that therapies targeting the PSMs may provide clinical benefit even in the presence of other spinal pathologies.

Level of evidence: 4.

Figure 1.. Identification of MC and CEP damage using conventional T1, fat-saturated T2-weighted, and UTE sequences.

The top panel shows CLBP patient with CEP damage and MC type 1 at L5/S1. The bottom panel shows a CLBP patient presenting CEP damage at L5S1 but no clear evidence of MC.

Figure 2:. Quantifying PSM fat fraction from IDEAL MRI.

First with identification of disc level using mid-sagittal T2 MRI (left), then manually outlining muscle boundaries in corresponding axial T1 MRI (top middle), then transposing ROI to corresponding axial IDEAL MRI (bottom middle). Segmentation of separate MF and ES muscles on an IDEAL scan provides mean fat fraction values (right)

Figure 3:. PSM FF and CEP damage.

Visual comparison using IDEAL MRI (fat fraction) of muscle quality differences at L4L5 between three subjects from our study: asymptomatic with L4L5 CEP damage (top), CLBP with L4L5 CEP damage (middle), CLBP without L4L5 CEP damage (bottom).