What is that noise when our joints pop, click or crack and what does it actually do?
A technique that I use from time-to-time is called HVT or High Velocity Thrust. Sometimes it is referred to as a manipulation or an adjustment by some professions.
This technique is used on the synovial joints which are joints that have fluid between the two bones. A side-effect of the technique can sometimes create a pop or click or crack.
The originally theories as to what was creating this noise was thought of as a ‘bubble popping’ however this has been debated and other theories have emerged.
The best, so far, I believe is something called tribonucleation. Simply put, it is a fancy term for a cavity formation.
If it is hard to imagine how creating a cavity makes noise… wet your hands with soapy water (you may be able to do it with dry hands), push your palms together at right angles to one another so that it pushes the air out. Then pull apart quickly. You should feel a mild pull or tension that holds your hands together before getting a slight pop.
This is effectively what I believe is happening when we ‘crack a knuckle’ or when I use manipulation or HVT techniques. So, what does it do?
Unfortunately, getting good quality research in this field is difficult as you are working with people’s pain and getting feedback on their treatment which can be influenced by a lot of other things. For example: If you are in a good or bad mood, if you liked or disliked the person treating you, if you woke up on the wrong side of the bed, if you over cooked your toast that morning… the list goes on!
Thus, the science around this subject is hazy at best. We know it has some ‘neurophysiological effect’ which means it may help reduce muscle tension, transiently improve range of motion and even reduce pain. Some patients describe it as feeling easier or better.
So, it may help in some way! YEY! But we shouldn’t rely on this technique alone as there can be too much of a good thing. Hence why with my treatments it is a mixture of HVT, massage, joint mobilisations, exercise, ergonomic and lifestyle advice and even diet.
You as a person are more than the sum of your bones and joints and so you should be treated as such!
Is HVT safe?
There are always risks with any type of treatment and HVT is not without risks.
However, with thorough questioning of lifestyle, medication, activity, family history etc enables me to measure the potential risk of injury or adverse event from treatment. This minimises the chance of any adverse events by using techniques appropriate for that patient.
If there is enough reason for me not to use the technique, this includes patients not wanting it, then I work around it.
As a helpful comparison of risk of death (quite extreme I know!) between HVT and various day-to-day activities can be seen below:
Estimated risk of serious adverse event (death):
Death from surgery to the neck = 1 person in around 145 operations
First time stroke = 1 person per 1,000 people in the general population in any one year
Non-steroidal anti-inflammatory drugs (NSAIDs like ibuprofen for osteoarthritis) = 1 person per 4000 in any one year
Death by road traffic accident = 1:20,000 people in any one year
Course of manipulative treatment = 1:400,000
As a helpful number to highlight the level of risk associated with HVT:
1 manipulation in every 100,000 to 1,000,000 has been related to a serious incident
Put another way, the average cost for car insurance accord