LYCOS RETRIEVER 
Cracking Knuckles: Joints
built 657 days ago
[J]ust as with knuckle cracking - the two bones will immediately return to the exact same position they were in prior to this little popping event. (At least you better hope they do because, if they don’t, you’re going to be in excruciating pain with a dislocated joint.)
Source:
[T]here is no evidence that habitual knuckle-cracking leads to arthritis....This... doesn't mean that [people] can't injure their finger joints in their popping-enthusiasm—by spraining capsular ligaments and/or cracking cartilage surfaces within these synovial joints. But casual and habitual popping doesn't appear to lead to anything much more than...more knuckle cracking.
Source:
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