The science behind spinal manipulation: debunking myths and embracing facts in this manual therapy technique
Manual therapy techniques - particularly spinal manipulations - have long been a subject of debate.
Many hands-on practitioners utilise these techniques to address a variety of musculoskeletal issues, such a back pain, neck pain and headaches.
However, misconceptions around how some of these manual therapies work and what they are doing in the body have led to unnecessary concern by some people.
Below we will investigate the scientific foundation of spinal manipulation and breakdown how these manual treatments are performed. We’ll also debunk some myths surrounding joint manipulations and explain how they work in the body.
Spinal manipulation: perception vs reality
People often imagine spinal manipulation as a forceful twisting or snapping of the spine, with the belief that something anatomically is out of place.
However, this perception is not grounded in anatomical reality.
In reality, spinal manipulation is a precise and controlled manual therapy technique. The aim is not to twist or relocate bones but to restore normal joint function and initiate the body’s natural healing process.
Understanding what happens at a joint level is crucial to dispelling these myths.
Understanding what a ‘manipulation’ is and what it does
When we use the term ‘manipulation’, we refer to a specific technique known as a high velocity low amplitude (HVLA) technique.
As the name suggests, this involves the rapid application of force over a short distance (or duration) within the anatomical (natural) range of motion of a joint.
This technique is applied when a restriction in motion has been identified.
A HVLA technique involves positioning the patient in a way that allows us to initiate a targeted movement to the restricted joint, followed by a thrust of appropriate force applied to engage the restrictive barrier.
HVLA techniques are used to re-establish normal joint operation. When a thrust is applied to a section of vertebrae, it should result in an opening of the joints on side of the spine, creating a cavity.
Studies have shown that joint manipulation induces various physiological responses at the joint level.
Rapid joint movements, as seen in a manipulation, impact pain perception and mobility.
It helps to improve the scope of movement in the joint, stretching the stiff tissue. It also helps to reduce pain by stimulating mechanoreceptors (sensory fibres that respond mechanical pressure).
The ‘popping’ sound during a joint manipulation
One of the most interesting aspects of spinal manipulation is the audible 'pop' that often accompanies the movement.
This sound is not bones snapping back into place, as commonly believed.
The formation of a cavity during a HVLA technique results in the dispersion of carbon dioxide within the joint, resulting in the audible ‘pop’, which we call cavitation.
Hearing a pop is likely an indication that there is sufficient movement occurring within the joint, but is not the goal of the technique.
The goal is to improve segmental mobility to restore optimal active range of motion.
There are research findings demonstrating that reductions in pain are achieved even when an audible pop is not heard.
The neurophysiological effects of joint manipulation
The impacts of manual therapy techniques, including spinal manipulation, are primarily neurophysiological, which means it impacts the function of the nervous system in the involved area.
Research suggests that these techniques lead to changes in pain perception, muscle tone and overall joint function. 3
In short, this means that as the neural sensory fibers are stimulated by the rapid opening of the joint, it initiates change in the behaviour of the local musculature, and the processing of sensory information arriving from that joint.
By targeting the nervous system, practitioners can achieve therapeutic effects beyond the mechanical aspects, emphasising the holistic nature of manual therapy.
Manual therapy techniques, particularly spinal manipulation, is a valuable tool in the hands of a skilled practitioner.
By understanding the scientific basis of these interventions, we can dispel myths and foster a more informed and positive perception of manual therapies such as joint manipulations.
It is essential to recognise that spinal manipulation is a precise and evidence-backed approach that focuses on restoring joint function and addressing neurophysiological aspects rather than physically 'untwisting' individuals.
Embracing the science behind manual therapy allows us to appreciate its effectiveness in promoting musculoskeletal health and overall well-being.
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