Non-specific effects

Neil - Doctor of PhysiotherapyBlog, Evidence, Physiotherapy0 Comments

I’ve had several conversations recently about specific and non-specific effects in manual therapy; it was the motivation behind the very recent ‘Post hoc’ logical fallacy post, and this theme often appears in the regular debates on social media surrounding ‘pain science’.

Manual therapy modulates pain and few clinicians would disagree with that however, the justification for using manual therapies are regularly hot topics.

Erik Meira wrote a wonderful piece about specific and non-specific effects last year: http://ptpodcast.com/understanding-specific-and-non-specific-effects/

The intended outcomes of a treatment intervention are typically to modify (or eliminate) unwanted symptoms (usually pain) and/or improve physical function, and those changes should always be measurable (objective). A client simply reporting that they “feel better” is subjective and not particularly helpful (or acceptable to the insurance company paying the bill). A client’s reported pain is also subjective but plotting that on a Visual Analogue Scale of ‘1-10’ turns a subjective experience into an objective measurement, whether that be within-session, between sessions, or over an extended period of weeks or months. Measuring how far a body part moves or how much load can be moved by it is also objective and easy to quantify.

Physical touch, of which there are *many* different forms, techniques and tools, can have a significant clinical improvement in most objective measures.

Referring to Erik’s post, knowing that it is the ‘load’ which has the specific effect on breaking a bone and not the way in which the load was delivered, we can apply the same reasoning to manual therapy. The ‘effect’ is reduced pain and improved function; the delivery interventions could come via a Physiotherapist, Chiropractor, Osteopathy, Myotherapist, Reiki practitioner, Yogi, crystal healing, hypnotherapist etc. The delivery method (profession or technique) is therefore not unique (specific) to reducing someone’s pain and improving their function.

A ‘technique’ may be unique to a profession however no technique in manual therapy has a specific effect on pain or function. Having a joint cracked, skin/muscle/tendons/nerves/fascia etc. massaged, stretched, cupped, pushed on, taped, poked at or stuck with needles has *zero* specific effect. They are simply different delivery systems.

So what IS the intervention from these delivery methods having a non-specific effect on someone’s pain and function?!

Great question!

People are extremely complex and there is no single answer however science has uncovered a very long list of non-specific effects of the interaction between a client and their therapist. In addition, the neurophysiological effects from physical contact with the skin are vast.

This http://physioaxis.ca/realitycheck.pdf shows us that:

➡️ Even though proven effective, manual therapies have not yet been consistently proven substantially superior to other forms of conservative care
➡️ There is no official consensus as to the mechanisms through which manual therapies exert their effects on painful conditions
➡️ Motion palpation tests, positional faults assessments, clinical postural assessments and many specific tests are poorly reliable.
➡️ Manual therapy has not been able to consistently demonstrate a lasting mechanical effect
➡️ The forces used in manual therapy cannot evoke plastic changes on the targeted tissue
➡️ Manual therapy tailored on the motion of palpation’s exam findings are no more effective than random application of manual therapy in the area where there is pain
➡️ There is no statistically or clinically relevant difference between the outcomes obtained by inexperienced and uncertified therapists and those of the more and experienced and certified ones
➡️ The relationship between pain and posture is not necessarily causal and the adoption of a different posture could just as easily be caused by the pain or the fear of experiencing it.
➡️ Manual interventions aiming at changing postures are most likely unable to do so by changing tissue length
➡️ Credible proof for neither existence nor causal relationship to pain is lacking for subluxation, fixation, a facilitated segment, and segmental hypomobilities.
➡️ Tissue length, form, position or symmetry remain poor predictors of pain

🔄 Important: Evidence of effectiveness is just that: evidence it has a positive effect. Evidence of effectiveness should not be mistaken with evidence of a sound, plausible and valid scientific theory. This is the logical fallacy: https://www.facebook.com/thekettlebellphysio/posts/358917221109502:0

For more on the effects of manual therapy, eee Bialosky et al (2009) ‘The Mechanisms of Manual Therapy in the Treatment of Musculoskeletal Pain: A Comprehensive Model’ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2775050/

The nonspecific effects of treatment have been promoted for the best part of two decades! In January 2011, an article from the International Association for the Study of Pain discussed the importance of maximising the effects of the ‘5 Es’, which had previously been published in 2001! http://www.iasp-pain.org/files/Content/ContentFolders/Publications2/PainClinicalUpdates/Archives/PCU_19-2_for_web_1390260453975_5.pdf

Erik Meira and J.W. Matheson also discussed at length the 5 Es (Engage, Empathise, Educate, Enlist and End) from the ISAP document in the second episode of the PT Inquest way back in April 2012 (http://ptpodcast.com/pt-inquest-episode-2-patient-activation-and-non-specific-effects/) and again in May 2014 the importance of the ‘Therapeutic Alliance’ (http://ptpodcast.com/pt-inquest-30-therapeutic-alliance/)

“the vast majority of outcome variance of any intervention for pain among humans goes unexplained. Much of this has to do with the unique aspects of the human brain and the individual’s need to interpret pain. Our thinking is dynamic, interactive, and context dependent. We seek meaning and understanding associated with perceived sensations, and this meaning is strongly related to our social networks and interactions. The
therapeutic quality of the practitioner’s manner and the role of expectations of treatment are very powerful, and we need to maximize that power in reducing the suffering of individuals with pain.” — IASP

This stuff is not new!

Wellens et al was published in 2010:

“The actual pain science literature has demonstrated that numerous humoral, chemical, physical, social and behavioural factors all contribute to a subject’s pain experience. The decision of the brain to output pain is based on the perceived threat of the numerous factors and their relative particular context. Anything that would increase the perceived threat is then likely to increase pain as well. Different factors such as stress, anxiety, hypervigilance, fear avoidance behaviours, memory, emotions and context are all potential variables that could influence how the brain perceives the stimuli it has to analyse. A simple explanation for a good part of the effectiveness of manual therapy could be that the novel stimulation introduced in the CNS by manual therapy may help the brain downregulate the perceived threat of current stimuli and thus decrease the pain by means of descending inhibition and other peripheral and central mechanisms the context in which the treatment is given, the treatment act itself, time and other variables will all account for the effect seen clinically after a course of manual therapy. In a neurophysiological model for manual therapy, both specific and non-specific reactions, including peripheral reflexive reactions and central/cortical processing could account for most, if not all the outcomes of a manual treatment aiming at reducing pain

The therapist in such a model then becomes more an interactor than an operator https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3172949/

“The only thing more expensive than education is ignorance” – Benjamin Franklin

– Image from Prof Peter O’Sullivan

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