From: utzoo!decvax!yale-com!leichter Newsgroups: net.med Title: Re: knuckle-cracking Article-I.D.: yale-com.724 Posted: Wed Jan 26 12:16:09 1983 Received: Sat Jan 29 09:14:51 1983 References: tekmdp.1708 The last article I saw on the subject (not that long ago and in some medical journal) stated that the actual mechanism in knuckle (or other joint) cracking was still unknown. The prevailing "best guess" was that it was caused by bubbles somehow getting introduced into the synovial fluid - in which the joints are bathed - and then bursting. I guess in this picture the feeling of relief you sometimes get when cracking, say, your back when it's stiff is the result of a bubble finally bursting and relieving a pressure build-up within the joint. -- Jerry decvax!yale-comix!leichter (oops, one tab too many...)