Do Participants With Low Back Pain Who Respond to Spinal Manipulative Therapy Differ Biomechanically From Nonresponders, Untreated Controls or Asymptomatic Controls?
SOURCE: Spine 2015 (Sep 1); 40 (17): 1329–1337 ~ FULL TEXT
Wong, Arnold Y. L. PT, MPhil, PhD; Parent, Eric C. PT, PhD;
Dhillon, Sukhvinder S. MB, ChB, CCST; Prasad, Narasimha PhD;
Kawchuk, Gregory N. DC, PhD
Department of Rehabilitation Sciences,
The Hong Kong Polytechnic University,
Kowloon, Hong Kong
Department of Physical Therapy,
University of Alberta,
|FROM: University of Alberta ~ 8-31-2015
Researchers at the University of Alberta have found that spinal manipulation—applying force to move joints to treat pain, a technique most often used by chiropractors and physical therapists — does indeed have immediate benefits for some patients with low-back pain but does not work for others with low-back pain. And though on the surface this latest conflict might appear to muddy the waters further, the results point to the complexity of low-back pain and the need to treat patients differently, says lead author Greg Kawchuk.“This study shows that, just like some people respond differently to a specific medication, there are different groups of people who respond differently to spinal manipulation.”
In a non-randomized control study, individuals with low-back pain received spinal manipulation during two treatment sessions that spanned a week. Participants reported their pain levels and disability levels after spinal manipulation, and researchers used ultrasound, MRI and other diagnostics to measure changes in each participant’s back, including muscle activity, properties within the intervertebral discs, and spinal stiffness.
A control group of participants with low-back pain underwent similar clinical examinations but did not receive spinal manipulation. A third group — those who did not have low-back pain symptoms — were also evaluated.
The people who responded to spinal manipulation reported less pain right away and showed improvement in back muscle thickness, disc diffusion and spinal stiffness. Those changes were great enough to exceed or equal the measures in the control groups and stayed that way for the week of treatment, the research team found.
Kawchuk, who practised as a chiropractor before going on to obtain his PhD in biomechanics and bioengineering, said the results do not advocate one way or another for spinal manipulation but help explain why there has been so much conflicting data about its merits.
“Clearly there are some people with a specific type of back pain who are responding to this treatment and there are some people with another type of back pain who do not. But if you don’t know that and you mix those two groups together, you get an artificial average that doesn’t mean anything,” Kawchuk explained.
The research team is still fine-tuning how to distinguish who is a responder or non-responder before spinal manipulation is given; however, this study shows it can be used to identify an effective treatment course.
“Spinal manipulation acts so rapidly in responders that it could be used as a screening tool to help get the right treatment to the right patient at the right time.”
The study did not investigate the long-term effects of spinal manipulation, but this is next on the list for the researchers.
STUDY DESIGN: Nonrandomized controlled study.
OBJECTIVE: To determine whether patients with low back pain (LBP) who respond to spinal manipulative therapy (SMT) differ biomechanically from nonresponders, untreated controls or asymptomatic controls.
SUMMARY OF BACKGROUND DATA: Some but not all patients with LBP report improvement in function after SMT. When compared with nonresponders, studies suggest that SMT responders demonstrate 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.
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METHODS: Participants with LBP and asymptomatic controls attended 3 sessions for 7 days. On sessions 1 and 2, participants with LBP received SMT (+LBP/+SMT, n = 32) whereas asymptomatic controls did not (-LBP/-SMT, n = 57). In these sessions, spinal stiffness and multifidus thickness ratios were obtained before and after SMT and on day 7. Apparent diffusion coefficients from lumbar discs were obtained from +LBP/+SMT participants before and after SMT on session 1 and from an LBP control group that did not receive SMT (+LBP/-SMT, n = 16). +LBP/+SMT participants were dichotomized as responders/nonresponders on the basis of self-reported disability on day 7. A repeated measures analysis of covariance was used to compare apparent diffusion coefficients among responders, nonresponders, and +LBP/-SMT subjects, as well as spinal stiffness or multifidus thickness ratio among responders, nonresponders, and -LBP/-SMT subjects.
RESULTS: After the first SMT, SMT responders displayed statistically significant decreases in spinal stiffness and increases in multifidus thickness ratio sustained for more than 7 days; these findings were not observed in other groups. Similarly, only SMT responders displayed significant post-SMT improvement in apparent diffusion coefficients.