The precise definition of the word “manipulation” to indicate a certain technique has always been quite problematic for manual therapists, and a recent paper attempts to pin it down to something neater which can be universally used and understood.
here is the link: https://pubmed.ncbi.nlm.nih.gov/36918833/
What do we mean by manipulation?
When I was at osteopathy college, back in the 90s, “manipulation” basically meant clicking a joint. This was usually the spine, but if you wanted to be a bit fancy-schmancy you could also click other joints – in the ankles, wrists, the radial head. In practice, patients often used the word manipulation in a more general way. “The physio manipulated my arm a bit”. When pressed for more specific details, their idea of manipulation seemed to mean moving something about and/or prodding it a bit.
Manip or HVT?
In notes I started my career writing “manip.” to indicate that I had clicked a joint, but as it did seem a bit vague and might be misinterpreted, I began to write HVT (for high velocity thrust) and if I was in a hyper defensive mood I would write HVLAT (high-velocity low-amplitude thrust – “hardly any force was used at all, your honour”).
Using the word manipulation in studies is currently confusing
Yet another problem with the vagueness of this word is that if it is used in a study without clarification, it renders the study meaningless. If you are comparing a group which has had manipulation with a group without, you really need to know which specific techniques have been used – is it general manual treatment, a bit of soft tissue? Mobilising? or a specific thrusting, cracking technique? Clearly, someone needed to end this confusion.
David Evans and Nicholas Lucas ride in to the rescue
So I was pleased to be introduced by colleague Jim Hurden to a study published earlier this year (March 2023), entitled What is Manipulation? A new definition, written by David Evans and Nicholas Lucas. These two have been published before, alongside famous physio Roger Kerry, no less, on the topic of causation. They have previously published on the topic of manipulation too, notably their 2010 paper “What is manipulation? A reappraisal” seeking to find a correct model for the technique. It seems they were hoping to inspire others to join them in their quest for the ultimate manipulation definition, but they were sadly disappointed. Everyone’s just so busy these days! On the bright side, evidence supporting their 2010 ideas grew and so they decided that to try to end the ongoing confusion, they might as well just finish the job themselves.
The definition
So, to cut to the chase, what is the definition they have come up with, and how? Well, the paper includes a nice table of examples of existing definitions from sources as diverse as the Ontario government, the Parliament of New South Wales and the Chartered Society of Physiotherapy. They looked at these to help them to decide which components to include, and which to exclude. The inclusion criteria had to be things that were always part of the technique, and the exclusion criteria – anything that was not absolutely essential to the definition:
- Therapeutic intent was deemed irrelevant, in the light of the current fad for posting anything and everything on social media for entertainment purposes only.
- It was very clear that the target of the technique is always a synovial joint, in any state of health.
- There was also a need to divide manipulation into the action of the one performing the technique, and the effect on the recipient. This response involves a “crack”, or “pop” – the result of the formation of gas bubbles, which result from decreased intracapsular pressure. (It’s a bit like popping bubble wrap, I say to patients, not totally sure if this is an entirely correct analogy, but it certainly demystifies things). Interestingly, the authors note that the best research on the cracking sound comes from bioengineers who were interested in knuckle cracking.
- For future-proofing purposes they decide not to include the origins of the action (i.e. a practitioner, or human) as being essential. Bring on the robots!
- Downstream consequences (i.e. physiological changes or therapeutic outcomes) are also excluded due to the fact that you can actually manipulate a dead body. (They include a surprising number of studies of cadaveric manipulation in their references. As someone who is halfway through season 3 of Dexter this doesn’t phase me in the slightest.)
- Not everyone feels improvement from a manipulation, and adverse events are possible, so beneficial outcomes are not in their final definition.
- The term “thrust” is deemed inappropriate as the way it is used colloquially is at odds with the formal scientific definition, which would apply to a ‘pushing back’, rather than pushing, force. It’s something to do with Isaac Newton and rockets – as they burn their huge amounts of fuel, that force creates an opposing reaction which propels the rocket up. So to be scientifically accurate, the ‘thrust’ in manipulation is the force back towards the practitioner from the patient. Let’s face it, it has slightly sexual connotations as well, so best avoided.
- “High velocity” should also be avoided, as you can manipulate quite slowly, sometimes.
So, drum roll…., here we are with the new definition, which the authors hope includes ALL the necessary components and “possesses minimal redundancy”, i.e. no waffle or pointless words.
Separation (gapping) of opposing articular surfaces of a synovial joint, caused by a force applied perpendicularly to those articular surfaces, that results in cavitation within the synovial fluid of that joint The definition can be broken down into 2 parts:
1. The action is a force applied perpendicularly to the articular surfaces
2. The mechanical response is Separation (gapping) of opposing articular surfaces of a synovial joint that results in cavitation within the synovial fluid of that joint
If any of those components are missing then this is NOT a manipulation, instead an “attempted” manipulation (we’ve all been there) .. ..If there is no cavitation, i.e. it seems to gap but there’s no popping sound, then we can call it “joint distraction”. If something clicks as an unintended side effect of you doing something else, well, it is an “unintended manipulation”.
Perpendicular? Does this word work?
Having discussed this with a few osteopaths, the sticking point we had was the word PERPENDICULAR. Is the thrust always perpendicular – i.e. at 90 degrees? This was news to me. Should I have known this? Is it common knowledge? Is it even true? Where does that leave us with lifts? A sacroiliac leg tug? This is the one reason why I feel I need more explanation before I can fully buy into this.
What next?
So, what with the manual therapy world being a veritable Tower of Babel, it would be great if we could all discuss this definition, in the hope of us all arriving at that happy land where we are all speaking the same language and understanding each other. Here’s a recap:
Summary of definitions
Manipulation: Separation (gapping) of opposing articular surfaces of a synovial joint, caused by a force applied perpendicularly to those articular surfaces, that results in cavitation within the synovial fluid of that joint
The action involved in manipulation: a force applied perpendicularly to the articular surfaces
The mechanical response : Separation (gapping) of opposing articular surfaces of a synovial joint that results in cavitation within the synovial fluid of that joint
Attempted manipulation: any of those components missing (it doesn’t ‘go’)
Joint distraction: no cavitation (it works but doesn’t pop)
Unintended manipulation: when it happens by chance
Thanks for reading, please do share or comment for purposes of discussion. I think the authors would be pleased to hear diverse views.
