In good news for knuckle crackers, radiologists from the UC Davis Health System have studied over 400 ultrasounds on the fingers of 40 frequent knuckle crackers, and found minimal adverse effects.

knucklesFrom the ultrasound studies, the researchers were firstly able to determine that the cracking noise comes from tiny gas bubbles that form instantaneously in the joints as you crack a knuckle. Interestingly, this is the opposite of what we have thought for a long time, as until now we have thought that the noise came from gas exploding out of the joint with the pressure of the cracking action. As the patients cracked their knuckles during this investigation, the researchers were able to visualise on scan an extremely distinctive, brilliant flash appearing in the joint. This flash was caused by the tiny gas bubbles forming in the joint, not bursting out of the joint.

The positive note was that the scans revealed no signs of joint damage in the participants who regularly cracked their knuckles. This outcome probably should be tempered by the fact we don’t know the age of the participants, how long they have cracked their knuckles and how frequently, and that ultrasound is not the best scan for visualising degenerative joint change – but good news none the less.

One other interesting finding in this study was that the researchers found that after cracking their knuckles, the participants demonstrated a significant increase in the range of movement of that particular joint, compared to the joints that weren’t cracked. Whilst there is no reason given for the improvement in joint range, it does fit in – the reason many of us crack joints (other than just habit) is that most of us find after our back/neck/fingers have cracked that there is a temporary loosening of that particular area, and a feeling of release of pressure.

Like most things in medicine, more research is required to come to a definitive conclusion, but at least for now we can say that the old wives’ tale of “cracking your knuckles gives you arthritis” may well be just that – an old wives’ tale!