Differences in the Thoracolumbar Fascia Between Low Back Pain Patients and Healthy Individuals: A Systematic Review with Meta-Analysis.

BACKGROUND: In view of new evidence revealing a mechanical and nociceptive role of the thoracolumbar fascia (TLF), it has been suggested to be involved in low back pain. OBJECTIVE: To compare characteristics of the TLF in low back pain (LBP) patients and asymptomatic controls. METHODS: Two independent investigators performed a systematic literature search using PubMed, Web of Science, Science Direct, Cochrane Library, and Google Scholar. Imaging studies (ultrasound/MRI) investigating the morphology and mechanics of the TLF in LBP patients and controls were included. We used robust variance estimation to pool (a) the standardized mean differences (SMD) between both groups and (b) the correlation between TLF characteristics and subjective pain ratings in LBP patients. RESULTS: A total of 14 trials with moderate-to-high methodological quality (5.1 ± 1.2 points on the JBI critical appraisal checklist) were identified. Relative to asymptomatic controls, the LBP patients displayed a higher thickness (SMD: 0.64, 95% CI 0.41 to 0.88, p = < .001, 12 studies), stiffness (SMD: 0.82, 95% CI 0.34 to 1.31, p = .018, 3 studies), and echogenicity (SMD 0.43, 95% CI 0.16 to 0.70, p = .02, 3 studies) of the TLF. No effect was found for fascial layers sliding (SMD: - 0.05, 95% CI - 5.82 to 5.71, p = .92, 2 studies), although both studies of this comparison found significant (opposite) difference to controls. TLF thickening correlated with higher pain ratings. CONCLUSION: The TLF of patients with LBP is thickened, stiffened and more echogenic when compared to controls, while the role of shear mobility is unclear. As we additionally found associations of TLF characteristics with pain ratings, future research addressing the predictive value of these markers is warranted.