In my chiropractic practise I am often asked he question, “Is it bad to crack my knuckles?” In my opinion this is likely an old wives tale but I figured it would be worth while to see if there is any research on the subject. I took some time and did a pubmed central review of the phrase, “habitual knuckle cracking”.
I found three research papers on the subject:
This study took 300 people 74 of which were admitted knuckle crackers (amount of cracking per day was not indicated) for 18 to 60 years and 226 non-knuckle crackers. Six-four (64%) percent of knuckle crackers had an increase in hand swelling where as 5.75% had hand swelling (this was statistically significant). Comparing grip strength, the habitual knuckle crackers’ strength was significantly less than the non-knuckle crackers ( 210 (50) mmHg v 280 mmHg). The knuckle crackers were also more often manual labourers with higher incomes who frequently smoked, drank alcohol, and bit their nails. The signs of osteoarthritis (Heberden and Bouchard’s nodes) were similar between the groups.
The authors wanted to see if knuckle cracking as a child resulted in degenerative changes in the hand in old age. This study took 28 people (average age of 78.5 years, 23 women and 5 men) who could recall whether or not they had or had not cracked their knuckles when they were younger. X-rays were taken of the hand. 28 school children (average age of 11 years, 8 girls and 20 boys) were surveyed to determine the prevalence of knuckle cracking in children. 15 of the adult subjects were knuckle crackers and 13 were not knuckle crackers. One of the 15 knuckle crackers had radiographic signs of arthritis where as 5 of the 13 non-knuckle crackers had signs of arthritis. The prevalence of knuckle cracking between the two ages were similar. Based on this information the authors concluded that knuckle cracking fails to lead to degenerative changes in the knuckles. And that … and this is made me laugh… “the chief morbid consequence of knuckle cracking would appear to be its annoying effect on the observer.”
In this study the authors sent out questionnaires to 319 participants (141 controls without hand osteoarthritis and 188 patients with arthritis) between the ages of 50 and 89. The questionnaires asked which fingers where cracked, how frequently, for how many years they cracked their knuckles, if there were any other risk factors for osteoarthritis and if they worked in manual labour for over 5 years. They received 215 surveys from the 329 participants (135 from patients with osteoarthritis and 80 from controls). Based on these questionnaires they determined there were no differences between controls and those with osteoarthritis based on number of years they cracked their knuckles, the frequency of cracking or working manual labour. They concluded, like the previous two research papers, that there is no association between knuckle cracking and the prevalence of osteoarthritis of the hand.
Based on these three studies I can answer to my chiropractic patients that, at this time, there is no association between knuckle cracking and osteoarthritis but there may be a decrease in hand strength.
So there you have it. The evidence has spoken, but it may change its mind sometime in the future.
Until next time