Physiotherapists, Osteopaths and chiropractors use several techniques that are consider ed“manual therapy”. These include mobilisation, soft tissue, myofascial release and many others names that can sound quite complex.
In relation to that, have you heard the name “manipulation” or “thrust”?
This technique is the one that created the audible ‘click’ and can be quite pleasant.
But have you ever thought about where the click is coming from?
What is the effect?
Spinal manipulation is a high-velocity low-amplitude procedure, characterised by a single, short quick movement direct at a target joint that often results in an audible sound. It is used to decrease pain and improve joint mobility and overall function.
There are several theories to explain the sound produced, but the most recent one describes the sound as a cavitation which is the formation of bubbles in a fluid when a mechanical effect induces a pressure drop.
Let’s go deeper into this:
Most of the joints in our body are covered by a “bag” (capsule) full of fluid (synovial fluid), creating a closed system. Within this closed system, the manipulation generates a rapid distraction of the articular surfaces that are in close contact. This creates a negative pressure which combined with the speed with which the surfaces separate, generates a vapour cavity within fluid that produces the sound.
In simple words, it can be described as a bubble being produced by negative pressure inside the joint.
For the effectiveness of the technique the sound is not mandatory. It has been reported that there is no relationship between the number of audible clicks during a manipulation and clinically meaningful improvements.
Also, the effect of the manipulations only last for a short period of time. The actual increase in the range of motion lasts for no more than 30 min, but the pain relief can last longer, becoming a useful period to introduce exercises that will provide the long term benefits.
The manipulation just creates a window of reduced pain to facilitate the muscle activation.
Commonly, patients have a misconception about the origin of cracking sounds heard during the manipulations, thinking for example that an anatomic structure is no longer in its normal position. These beliefs can become harmful as they give wrong ideas, suggesting that the back is fragile and that professional help is regularly needed to restore normal alignment, ultimately affecting the outcomes, perpetuating symptoms or the chronicity of them.
In conclusion it is important to understand that the so called miracles cures produce just a short term effect that has to be complement with others, particularly with exercises, to reinforce the effect achieve and get a more long term effect. Moreover it is important to recognise that is only one of the possible techniques available, so there are hundreds of ways to achieve the same outcome.