Shear wave elastography based analysis of changes in fascial and muscle stiffness in patients with chronic non-specific low back pain

Kun Liu; Tong Zhao; Yang Zhang; Lili Chen; Haoran Zhang; Xiqiang Xu; Zenong Yuan; Qingyu Zhang; Jun Dong

doi:10.3389/fbioe.2024.1476396

Shear wave elastography based analysis of changes in fascial and muscle stiffness in patients with chronic non-specific low back pain

Front Bioeng Biotechnol. 2024 Nov 15:12:1476396. doi: 10.3389/fbioe.2024.1476396. eCollection 2024.

Authors

Kun Liu^#^{1

2}, Tong Zhao^#³, Yang Zhang^#¹, Lili Chen², Haoran Zhang⁴, Xiqiang Xu⁴, Zenong Yuan⁴, Qingyu Zhang⁴, Jun Dong⁴

Affiliations

¹ Rehabilitation and Physical Therapy Department, Shandong University of Traditional Chinese Medicine Affiliated Hospital, Jinan, China.
² College of Sports and Health, Shandong Sport University, Jinan, Shandong, China.
³ Shandong Academy of Occupational Health and Occupational Medicine, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong, China.
⁴ Department of Orthopedics, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China.

^# Contributed equally.

Abstract

Background: The quantitative assessment of individual muscle and fascial stiffness in patients with low back pain remains a challenge. This study aimed to compare the stiffness of the thoracolumbar fascia (TLF), erector spinae (ES), and multifidus (MF) in patients with and without chronic non-specific low back pain (CNLBP) using shear wave elastography (SWE). It also sought to explore the relationship between muscle and fascial stiffness and the levels of pain and dysfunction in patients with CNLBP.

Methods: In this cross-sectional study, 30 patients with CNLBP (age 27.40 ± 4.57 years, 19 males, 11 females, BMI 22.96 ± 2.55 kg/m²) and 32 healthy controls (age 27.94 ± 4.94 years, 15 males, 17 females, BMI 22.52 ± 2.26 kg/m²) were enrolled. Stiffness of the TLF, ES, and MF was measured using SWE, and Young's modulus values were recorded. The numeric rating scale (NRS) for quantifying pain intensity and the Oswestry Disability Index (ODI) scores were recorded for the case group to examine their correlations with the resilience index.

Results: The CNLBP group exhibited significantly higher shear modulus values at the L_4-5 bilateral TLF (left: p = 0.014, d = 0.64; right: p = 0.002, d = 0.86), ES (left: p = 0.013, d = 0.66; right: p = 0.027, d = 0.58), and MF (left: p = 0.009, d = 0.69; right: p = 0.002, d = 0.85) compared to the control group. Comparable findings were observed for the right ES (p = 0.026, d = 0.59) and left MF (p = 0.020, η ² = 0.09) at L_1-2. Strong correlations were observed between the shear modulus of the bilateral TLF (left: r = 0.57, p = 0.001; right: r = 0.65, p < 0.001) at L_4-5 and the NRS scores. Moderate correlations were noted between the shear modulus of the ES (left: r = 0.42, p = 0.022; right: r = 0.48, p = 0.007) and MF (left: r = 0.50, p = 0.005; right: r = 0.42, p = 0.023) at L_4-5 and the NRS scores. Additionally, the shear modulus of the MF (r = 0.50, p = 0.005) on the left side of L_1-2 showed similar correlations. Strong correlations were observed between the shear modulus of the bilateral TLF (left: r = 0.60, p < 0.001; right: r = 0.58, p < 0.001) at L_4-5 and the ODI scores. Moderate correlations were observed between the shear modulus of the right TLF (r = 0.43, p = 0.017), ES (r = 0.38, p = 0.037), and MF (r = 0.44, p = 0.015) at L_1-2, as well as the bilateral MF (left: r = 0.46, p = 0.011; right: r = 0.45, p = 0.012) at L_4-5, and the ODI scores. No significant correlations were found at other measurement sites.

Conclusion: In patients with CNLBP, the stiffness of the lumbar fascia and muscles is generally higher than in individuals without LBP. However, this increase is not uniform across all lumbar regions, with the most significant changes observed in the L_4-5 segments. In addition, higher stiffness may be associated with pain and dysfunction, primarily manifested in the TLF.

Keywords: erector spinae; low back pain; multifidus; shear wave elastography; thoracolumbar fascia.