Background: Thoracolumbar fascia mobility observed with ultrasound imaging and calculated as shear strain is lower in persons with chronic low back pain. This pilot and feasibility trial assessed thoracolumbar shear strain in persons with chronic low back pain following spinal manipulation and over an 8-week course of multimodal chiropractic care.
Methods: Adults self-reporting chronic low back pain ≥ 1 year participated between September 2019 and April 2021 in a trial using ultrasound imaging to measure thoracolumbar shear strain. Ultrasound imaging occurred 2–3 cm lateral to L2-3 while participants relaxed prone on an automated table moving the lower extremities downward 15 degrees, for 5 cycles at 0.5 Hz. Pain intensity on an 11-point numerical rating scale, disability, pain interference, and global improvement were also collected. Participants received 8-weeks of twice-weekly chiropractic care including spinal manipulation, education, exercise, self-management advice and myofascial therapies. Shear strain was computed using 2 methods. The highest shear strain from movement cycles 2, 3, or 4 was averaged over right and left sides for each participant. Alternately, the highest shear strain from movement cycle 3 was used. All data were analyzed over time using mixed-effects models. Estimated mean changes are reported.
Results: Of 20 participants completing 8-weeks of chiropractic care (female n = 11), mean (SD) age was 41 years (12.6); mean BMI was 28.5 (6.2). All clinical outcomes improved at 8-weeks. Mean (95% confidence interval) pain intensity decreased 2.7 points (− 4.1 to − 1.4) for females and 2.1 points (− 3.7 to 0.4) for males. Mean Roland–Morris disability score decreased by 5 points (− 7.2 to − 2.8) for females, 2.3 points (− 4.9 to 0.2) for males. Mean PROMIS pain interference T-score decreased by 8.7 points (− 11.8 to − 5.5) for females, 5.6 points (− 9.5 to − 1.6) for males. Mean shear strain at 8-weeks increased in females 5.4% (− 9.9 to 20.8) or 15% (− 0.5 to 30.6), decreasing in males 6.0% (− 24.2 to 12.2) or 2% (− 21.0 to 16.8) depending on computational method.
Conclusion: Spinal manipulation does not likely disrupt adhesions or relax paraspinal muscles enough to immediately affect shear strain. Clinical outcomes improved in both groups, however, shear strain only increased in females following 8-weeks of multimodal chiropractic care.
Trial registration ClinicalTrials.gov registration is NCT03916705.
Author keywords: Fascia - Low back pain - Chiropractic - Shear strain - Ultrasound
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