Quantitative ultrasound evaluation of the thoracolumbar fascia after manual and acupuncture therapies: an exploratory mechanistic randomized controlled trial with a sequential within-subject phase

Abstract Objective Thoracolumbar fascia (TLF) alterations may contribute to nonspecific low back pain (NSLBP). We evaluated the effects of acupuncture, chiropractic care, and massage on TLF biomechanics, microstructure, and clinical outcomes in NSLBP. Materials and methods In this exploratory mechanistic hybrid trial, sixty participants (median age: 47 years [interquartile range 39–63]; 63% women) were randomized (1:1:1) to acupuncture, chiropractic, or a 3-week waitlist control, providing between-group comparisons. After the waitlist, control participants received massage therapy, enabling a sequential within-subject evaluation. Pre- and post-intervention assessments included TLF shear strain (ShS)—cumulated (C|ShS| L ) and maximum (Max|ShS| L ) absolute lateral strain—homodyned K-distribution (HKD) parameters, and clinical scores. Analyses used linear mixed-effects models, Fisher’s exact test, and Spearman’s rank correlation. Results In the randomized comparison, C|ShS| L decreased with chiropractic ( β : -16%, 95% confidence interval [-29, -2]; p = 0.021; d = -0.322), but not with acupuncture ( p = 0.130), and increased in controls ( β : +19%, p = 0.003; d = +0.387), with a smaller rise in Max|ShS| L ( β : +0.4%, p = 0.048). Massage following the control phase reduced C|ShS| L ( β : -32%, p < 0.001; d = -0.673) and Max|ShS| L ( β : -0.5%, p = 0.010). The control–massage phase interaction effect size for C|ShS| L was large ( d = 1.082). HKD parameters remained unchanged. Only chiropractic yielded improvement in the Oswestry disability index (ODI) ( p = 0.041). No correlation was observed between changes in C|ShS| L and ODI (ρ = 0.261; p = 0.054). Conclusion Chiropractic and massage, unlike acupuncture, elicited detectable biomechanical changes, while chiropractic also enhanced disability outcomes. HKD detected no microstructural changes. Trial registration Clinicaltrials.gov, NCT04843800. Registered April 14, 2021 ( https://clinicaltrials.gov/study/NCT04843800 ). Relevance statement This study shows that ultrasound-derived shear strain captures the short-term mechanical responses of the thoracolumbar fascia to chiropractic care or massage therapy in participants with chronic nonspecific low back pain, supporting the potential role of quantitative fascial imaging biomarkers for mechanistic assessment and treatment monitoring of this prevalent, debilitating disorder. Key Points Recent research suggests that altered microstructure and biomechanics of the thoracolumbar fascia may contribute to nonspecific low back pain. In this randomized trial, chiropractic care, but not acupuncture, reduced thoracolumbar shear strain, while controls showed increased strain. In the within-subject sequential analysis, thoracolumbar shear strain increased during the waitlist phase and decreased after massage therapy. No microstructural changes were detected over 3 weeks, potentially reflecting biological constraints and/or limitations in measurement sensitivity. Small sample size and low baseline disability likely limited the trial’s power to detect significant effects on clinical outcomes.