HVLA stands for high velocity, low amplitude. Essentially a HVLA manipulation is a technique where a Physiotherapist, Chiropractor, Osteopath or some other form of manual therapist, applies a short, quick thrust to one of your joints- most commonly a spinal joint, with the aim of physically moving a joint in a particular direction, and / or providing a specific form of sensory input, with an expectation that it will result in a favourable clinical outcome. The hypothesised mechanism of action held up by a given provider varies widely, depending on the provider’s education, motivations, biases and the culture within which he or she operates. There are some licensed manual therapists who believe that HVLA manipulations can cure cancer, autism, deafness and allergies. Extraordinary claims, but not backed up by scientific evidence. I emphasise the word believe, because such claims lie outside of the field of scientific analysis.
Perhaps more startling, is the fact that there are manual therapists who believe such things, in the absence of reasonable evidence, who are not answerable to any independent licensing body or regulator. At the other end of the spectrum, there are other manual therapists for whom believing is not a factor, but rather, their view on whether or not to utilise HVLA manipulation is guided by a thorough examination of and evolving understanding of the available scientific literature.
Humans have been cracking each other’s joints for hundreds of years. Over the last century or so the Chiropractic profession, and perhaps also the profession of Osteopathy emerged from the USA, as the professions most strongly associated with the use of the HVLA technique. Some of the more indefensible claims about the effects of HVLA, and the purported mechanisms of effect, originated from the fanciful ideas of the founding father of Chiropractic, a gentleman known called D.D Palmer. The creator of Osteopathy, Andrew Taylor Still, might take credit for some of those too. Thankfully, many of today’s Chiropractors and Osteopaths have managed to shake off the indefensible explanations and purported effects (and purported mechanisms) of HVLA manipulation, and have relied upon science, and critical thinking to either stop providing HVLA, or use it far less indiscriminately, with a far more defensible rationale. Not all of them have though. And it is not just limited to the Chiropractors and Osteopaths. Physical Therapists in the USA and Physiotherapists in other countries have lobbied hard in the past for the right to perform HVLA manipulations. It seems that regardless of the specific manual therapy profession being questioned, there appears to exist a spectrum of dubious justifications for the use of HVLA manipulation. These range from the holding up of scientific evidence demonstrating short term efficacy, while ignoring higher level research demonstrating a lack of long term superiority of effect… to justifications that are patently baseless, inappropriate, indefensible, useless and harmful.
Anecdotally, the immediate effect of a HVLA is often quite remarkable. Many report instant relief of pain or tightness in the area where the intervention is applied. I have observed this as both provider, and receiver of such interventions over the years. As already noted, this is backed up by some scientific literature too. Researchers have demonstrated a superior effect of HVLA to the spine compared to non HVLA interventions (such as mobilisation) for certain sub-groups of patients. However, taken in its totality, the scientific literature tends to point away from there being any significant superior long term benefits of HVLA interventions compared with other interventions for the broader population.
BENEFITS OF HVLA
My position on the benefits of HVLA manipulation is that as a “consumer” of health services, you can either take or leave HVLA. The evidence suggests that in the long term, you won’t be missing out on anything if you decide to reject any manual therapist’s offer to perform a HVLA manipulation. More important than the question “Should I allow a manual therapist to HVLA my spine (or other joint)?” is, I think, the question “Why is the manual therapist offering to HVLA my spine (or other joint) at all?”.
This latter question is the one you, the consumer of health services need to have the courage to ask when you consult with a manual therapist. As a rough guide, if you do ask your manual therapist “why should I let you HVLA my spine?”, I would suggest declining the offer of a HVLA manipulation if you receive any of the following answers;
Your symptoms will not resolve if you do not let me HVLA your spine
Your symptoms will return if you do not let me HVLA your spine
Your risk of disease will be increased if you do not let me HVLA your spine
I need to HVLA your spine because you have vertebral subluxation
I need to HVLA your spine because your vertebrae are out of place, or mal-aligned
HVLA to your spine can cure (insert name of any disease or illness that you are unfortunate enough to suffer from)
Perhaps there are other examples readers can provide. If your manual therapist does make any of these claims, you would be safe to assume that he or she is adhering to a woefully outdated and inaccurate framework of understanding of human anatomy and physiology. Your manual therapist may very well be a lovely person, and may be full of genuinely good intentions… But such claims are indefensible, unverifiable, unfalsfiable, and are thus, anti-scientific. Assuming it is important to you to that the manual therapist you choose to consult with, works from a science and evidenced based platform, you can find a better manual therapist than the one who makes any of the six claims above.
As far as any risks associated with HVLA manipulation are concerned, one could argue that there is an insidious risk of the perpetuation of erroneous understanding of human disease, injury, pain, and appropriate treatment of it. Erroneous understanding, from both provider and receiver of health services, sets the scene for unintended consequences. In relation to the application of HVLA, a risk is that you develop an unnecessary dependency on the treatment e.g. It’s possible that you come to believe that “I have to have my back cracked once a month to stay healthy”. At best, this might manifest as nothing more than an unnecessary expense for you, with no other adverse impact on your life. At worst, your faith in such treatment might lead you to make fatally poor decisions about treatment, if / when serious disease strikes you or your family.
With regards to specific risks of injury or other adverse events from HVLA manipulation, a decades long debate has raged, particularly in relation to the upper cervical spine (upper neck). That particular debate centres around the risk of there being a stroke event either triggered or catalyzed by a HVLA manipulation to the upper cervical spine, by way of vertebral artery tearing or a dislodging of an already formed arterial blood clot. To read further on this issue, please check out this post, and this post. You may also like to read up on the work of Roger Kerry, a researcher in the area of cervical artery dysfunction, stroke and manual therapy. It may also be useful to read up on the work of David Cassidy.
My position on the debate regarding the risk of stroke from having one’s upper neck HVLA manipulated, is that the prevalence of such events is too low to be measured in a conclusive manner. The best we can do in deciding to utilise HVLA to the cervical spine is to be risk averse, or not. My position is that, when weighed against the evidence that suggests that you, the patient will not be any worse off if I don’t offer you a HVLA for your neck pain, the very very very small risk of a stroke just isn’t worth it. So I no longer offer HVLA manipulation to the upper cervical spine of my patients. I encourage other manual therapists to consider the same logic.
The best way you, the consumer, can guard against any of these risks, no matter how rare they are, is to educate yourself. I plan to stay informed on this topic, and to update this page as new information is made available. For now, if you do see a manual therapist who offers to HVLA your neck, and assuming he or she doesn’t “fail” by providing any of the six bogus sales pitches listed above, I would ask two more questions before allowing him or her to HVLA your neck.
Can you guarantee me that I have no current vascular pathology in my cervical arteries, which as a result of a HVLA to my upper cervical spine, might lead to the tearing of an artery wall and / or the dislodging of a blood clot, resulting in a stroke event?
Will I be any worse off in the long term if you carry out a treatment other than HVLA to my neck?
If your Physio, or Chiro, or Osteopath etc, is on his or her game, the answers should be no and no. From there it's up to you to weigh up whether or not it is worth it.