One of the most common questions that a chiropractor is likely to be asked is, "What's that cracking sound?" Typically, you'd have no trouble explaining the mechanism of cavitation and its relevance to an adjustment. Often this line of questioning is followed by a secondary probe such as, "But doesn't it cause arthritis?" Again, you may have no difficulty refuting the suggestion, but do you actually have any evidence for your assertion?
A recent case-controlled study in the Journal of the American Board of Family Medicine (1) looked at the relationship between habitual knuckle cracking and eventual osteoarthritis. Interestingly they found "in these cohorts of persons aged 50 to 89 years, a history of habitual knuckle cracking - including the total duration and total cumulative exposure to knuckle cracking - does not seem to be a risk factor for hand OA."
deWeber and colleagues also posed the question as to why an individual might develop such a habit in the first place, and suggested that it might offer some relief to perceived joint stiffness. It has also been suggested elsewhere that the tendency to crack the knuckles is born out of the close neurological relationship between the hands and the cortex of the brain. In essence, manipulating the distal joints has a profound stimulatory effect upon the cortex and may serve as a 'manual caffeine' to give us a mental lift. Perhaps this is why we tend to crack our knuckles when trying to concentrate, in much the same way as a child with ADHD will fidget to aid concentration. Whatever the reason for the habit, it doesn't seem to cause us any problems.
Dr Matthew D. Long - BSc. M.Chiro
(This article has been reprinted with permission from Dr Matthew D Long .The numbers throughout this article refer to a full list of references available at reception on request)