Mechanism of Action of Spinal Mobilizations: A Systematic Review
One page on PainSci cites Aguirrebeña 2016: Does Spinal Manipulation Work?
PainSci notes on Aguirrebeña 2016:
That spinal joint? Probably not “stuck” or “out.”
There’s a lot to unpack in this paper, a review of the science of how spinal manipulation may or may not work. But I mainly want to emphasize this conclusion: they found no evidence that spinal manipulation has “an effect on segmental vertebral movement.”
There may be other effects of manipulating the spine, and this paper discusses some of those: “neurophysiological effects resulting in hypoalgesia (local and/or distal to mobilization site), sympathoexcitation, and improved muscle function.” Plenty to discuss in there.
But the most interesting evidence-based opinion here is that the movement of a spinal joint does not change/improve after “adjustment” by chiropractors, osteopaths, and physical therapists. It’s important because it directly challenges one of the worst and oldest ideas in all of musculoskeletal medicine: that spinal joints can be “out” or “stuck” in a way that can be fixed by someone’s skilled hands. If intervertebral joints suffer from any kind of movement dysfunction in the first place — a separate question — this paper concludes that it’s unlikely that they can be put right. But it’s more likely that the premise is also bogus, and joints are rarely “stuck” or “out” in a clinically significant way in the first place.
original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
STUDY DESIGN: Systematic review.
OBJECTIVE: To review the evidence regarding the mechanism of action of mobilizations.
SUMMARY OF BACKGROUND DATA: Spinal mobilizations-low velocity passive oscillatory movements-reduce spinal pain in some patient subgroups. Identifying patients likely to respond remains a challenge since mobilizations' mechanism(s) of action are unclear.
METHODS: Medline, Web of Science, Cinahl, Embase, and Scopus databases were searched for relevant studies. Reference lists of included studies were hand searched. Studies were included if the intervention was passive spinal mobilizations, participants were symptomatic, and outcomes evaluated possible mechanisms of action. Methodological quality was independently assessed by two assessors using a modified Cochrane Back Review Group tool.
RESULTS: Twenty-four studies were included in the review. Four were classified high risk, 14 moderate risk, and four low risk of bias. Commonest methodological limitations were lack of participant blinding, adequate randomization and allocation concealment, and sample size calculation. Evidence suggests that spinal mobilizations cause neurophysiological effects resulting in hypoalgesia (local and/or distal to mobilization site), sympathoexcitation, and improved muscle function. Mobilizations have no effect on temperature pain threshold. Three of four studies reported reduction in spinal stiffness, heterogeneous in location and timing. There is limited evidence (one study in each case) to suggest that mobilizations produce increased nociceptive flexion reflex threshold, improved posture, decreased concentration of substance P in saliva, and improved sway index measured in cervical extension. Evidence does not support an effect on segmental vertebral movement. Two studies investigated correlations between hypoalgesia and mechanism: one found a correlation with sympathoexcitatory changes, whereas the other found no correlation with change in stiffness.
CONCLUSION: These findings suggest involvement of an endogenous pain inhibition system mediated by the central nervous system, although this is yet to be investigated directly. There is limited evidence regarding other possible mechanisms.
LEVEL OF EVIDENCE: 3.
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- Placebo analgesia in physical and psychological interventions: Systematic review and meta-analysis of three-armed trials. Hohenschurz-Schmidt 2024 Eur J Pain.
- Recovery trajectories in common musculoskeletal complaints by diagnosis contra prognostic phenotypes. Aasdahl 2021 BMC Musculoskelet Disord.
- Cannabidiol (CBD) products for pain: ineffective, expensive, and with potential harms. Moore 2023 J Pain.
- Moderators of the effect of therapeutic exercise for knee and hip osteoarthritis: a systematic review and individual participant data meta-analysis. Holden 2023 The Lancet Rheumatology.
- Inciting events associated with lumbar disc herniation. Suri 2010 Spine J.