Ultrasound Shows Why Knuckles Are so Noisy
Written by Editor   
Friday, February 19, 2016 12:00 AM

Pop go the gasses…

The knuckle-cracking debate continues, with the latest evidence suggesting the resulting "pop" is due to cavity formation in the joint that subsequently allows dissolved gasses to escape.

Knuckles cracked under the surveillance of ultrasound imaging showed a cavity forming that corresponded with the cracking sound, followed by a white flash of gas that eventually dissipated. Researchers studied a total of 40 adults, 30 of whom habitually cracked their knuckles, and 10 who did not. They took ultrasound images of knuckles cracking and not cracking, totaling some 400 scans.

Overall, they found no clinical differences between knuckle-crackers and those who don’t pop their knuckles, with no differences in grip strength or in range of motion between groups.  But those who cracked their knuckles did seem to have greater laxity, which is the ability to move beyond a commonly accepted range of physiologic motion.

Although researchers said they're confident that the study indicates the popping sound and subsequent bright flash are associated with a cavity forming and gasses being released, they said further study is needed to assess any long-term hazard or benefit of knuckle cracking.

Source:  http://www.medpagetoday.com/MeetingCoverage/RSNA/54968