Do participants with low back pain who respond to spinal manipulative therapy differ biomechanically from non-responders, untreated or asymptomatic controls?

The aim of this study was to determine if low back pain (LBP) patients who respond to spinal manipulative therapy (SMT) differ biomechanically from non-responders and untreated asymptomatic controls. Some, but not all LBP patients report improvement in function after SMT. When compared to non-responders, studies suggest that SMT-responders exhibit significant changes in spinal stiffness, muscle contraction and disc diffusion. Unfortunately, the significance of these observations remains uncertain given methodological differences between studies including a lack of controls. LBP participants and asymptomatic controls attended three sessions over 7 days. On sessions 1 and 2, LBP participants received SMT (+LBP/+SMT, n = 32) while asymptomatic controls did not (-LBP/-SMT, n = 57). In these sessions, spinal stiffness and multifidus thickness ratios were obtained prior to and following SMT and on day 7. Apparent diffusion coefficients (ADC) from lumbar discs were obtained from +LBP/+SMT participants before and after SMT on session 1 and from a LBP control group that did not receive SMT (+LBP/-SMT, n = 16). +LBP/+SMT participants were dichotomized as responders/non-responders based on self-reported disability on day 7. A repeated measures ANCOVA was used to compare ADCs among responders, non-responders and +LBP/SMT, as well as spinal stiffness or multifidus thickness ratio among responders, non-responders and -LBP/-SMT subjects. After the first SMT, SMT-responders displayed statistically significant decreases in spinal stiffness and increases in multifidus thickness ratio sustained over 7 days; these findings were not observed in other groups. Similarly, only SMT-responders displayed significant post-SMT improvement in ADC.

Those reporting post-SMT improvement in disability showed simultaneous changes between self-reported and objective measures of spinal function. This coherence was not observed in asymptomatic controls or no-treatment controls. These data imply that SMT impacts biomechanical characteristics within SMT-responders not present in all LBP patients. This work provides a foundation to investigate the heterogeneous nature of LBP, mechanisms underlying differential therapeutic response and the biomechanical and imaging characteristics defining responders at baseline.

Neck Pain

Out of all 291 conditions studied in the Global Burden of Disease 2010 Study, neck pain ranked 4th highest in terms of disability and 21st in terms of overall burden.

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