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What’s the Crack? An overview of the effects of Osteopathic manipulation

Manipulation is a technique used by Osteopaths, Chiropractors and some Physiotherapists in order to improve symptoms of painful conditions such as back pain or headaches. These techniques were developed over 2000 years ago and have been tweaked along the way. With modern science and technology we can now give a more clear overview on the effects both physical and physiological.

'What's the crack?' is a common question asked in clinic. Often the belief is we are putting the bones back into place or realigning the spine. The actual effect, and my answer to this question, is much more than you think. There are largely three things happening; a physical affect, a physiological affect and a neuro-physiological affect.


The target of manipulation is a joint, generally in the spine. A joint is made up of two bone surfaces meeting to create a hinge surrounded by a capsule and filled with lubricating fluid. In certain conditions the bony surfaces can be pressurised by a vacuum effect thus restricting the freedom of movement. The physical effect of manipulation is called a cavitation or pop. This pop is the sound made when releasing the vacuum, much like the noise made when cupping your hands together and releasing them.


Releasing the vacuum allows the two surfaces to move independently and thus increases range of movement but we also see an increase in blood flow locally and the stimulation of the bodies threat system. With this our motor control improves, inflammation is reduced and the pain threshold increases. These fast acting effects give short term benefits in reducing pain, restricted mobility and stress and showing your brain a way to break the 'pain – spasm – pain' cycle.


Neuro-physiological refers to the changes in your brain as a result of an input. Our brain will always try to maintain homeostasis and as such respond to stimuli. A manipulation is seen by the brain as a threat or an over stimulation to the local area both mechanically and chemically. The Endocannabinoid system starts to work by releasing a set of neurotransmitters (chemicals) in order to supress the painful signals reaching the brain. The pain killing response reduces spasm as well as stress (both physical and emotional) allowing a circuit breaking analgesic effect. When combined, the interaction of these three effects allows more movement, less inflammation and sustained changes to the pain cycle.

There are of course limitations to all techniques and your practitioner will walk you through your options but hopefully this explains a little more about what the crack is.

Finally remember we are here if you need any advice and if you have any questions, please don't hesitate to contact us.

Joe Allnutt - Director & Osteopath

Read more about Joe in Our Team section


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