Most of us have, either intentionally or not, heard or felt a ‘popping’ sensation in our joints. Whether it is the knuckles, spine or ankles – it happens commonly, but what is that noise? Well, it seems the clinical jury is still out, however there are prevalent theories which seem to give the most accurate answer. In our hands (along with many other areas in the body) we have synovial joints – which allow for movement. Between each joint there is synovial fluid, an almost ‘egg white’ consistency fluid which lubricates and protects the joint surfaces. One study found that the ‘popping’ sound which happens when a finger or joint is extended is caused by pressure inside the joint lowering dramatically as the extension happens, followed by gases inside the joint collapsing and are released in the form of a bubble – sounds complex, but the takeaway point here is the popping sound (also known as a cavitation) is due to vacuum (the joint being pulled or extended) being filled by gas, which then collapses due to the pressure from the pulling or movement of the joint – causing the popping or cracking noise that we hear.
But I crack my knuckles all the time……is it bad?
Although it has been a myth for decades that cracking your knuckles ‘will give you arthritis’ there is actually no good evidence at all to show that this happens. One study showed a very minor decrease in grip strength due to knuckle cracking, but nothing more severe. Around 25 – 55% of the UK population crack their knuckles (men more than women apparently). So what is the take home point here regarding the hands and knuckles? Well, all current evidence would indicate that habitual knuckle cracking correlates with jobs involving manual labour, people who bite their nails, and people who frequently smoke and drink alcohol. If you are worried about cracking your joints, or joint pains – give the clinic a call for some advice!
Joshua Myers. MSc Ost Med. Registered Osteopath
Citations:
Chan PS, Steinberg DR, Bozentka DJ. Conse- quences of knuckle cracking: a report of two acute injuries. Am J Orthop 1999;28:113–4.
Protopapas MG, Cymet TC. Joint cracking and popping: understanding noises that accompany articular release. J Am Osteopath Association 2002;102:
283–7.
Unsworth A, Dowson D, Wright V. ‘Cracking joints’. A bioengineering study of cavitation in the metacarpophalangeal joint. Ann Rheum Dis. 1971 Jul;
30(4):348–358.
