COVER STORY RESEARCH Sound science New research shows joint cavitation theory not all it’s cracked up to be by mike straus A new paper in the Journal of the Canadian Chiropractic Association indicates that the most widely accepted theory to date of joint cracking fails to explain why joints produce sound when cracked – and may lead to inac-curate predictions relating to health outcomes. Dr. Jerome Fryer’s interest in investigating joint cracking is twofold. The Nanaimo, B.C.-based chiropractor’s pro-fessional interest stems from his research and practice in the field of chiropractic. However, as the subject of a 2015 study on joint cracking that he co-authored with University of Alberta profes-sor and chiropractor Dr. Greg Kawchuk, he demonstrated an uncanny ability to crack his knuckles on demand. Fryer is also the primary author of a new study recently published in the Journal of the Canadian Chiropractic Association that challenges the chiro-practic field’s current understanding of the factors that cause joints to crack. “I’m interested in knuckle cracking because it’s an easy way to study spine cracking,” Fryer says. “Knuckles are easy joints to access and test, but everything we learn from knuckles can be extrap-olated to the spine.” EXCELLENCE IN RESEARCH At its annual general meeting in 2015, the British Columbia Chiropractic Assocation recognized Dr. Jerome Fryer for his dedication to spine research. Fryer’s new study examines the mechanism of joint cracking using five in vitro joint models, drawing from his previous work with Kawchuk to further make use of the methodology that he’d perfected. “During the Kawchuk study (“Real-Time Visualization of Joint Cavitation”), I used a dry suction cup release to represent the sound simi-lar to a knuckle crack,” Fryer explains. “After that study, I decided to introduce fluid into the model. Through trial and error, the model created a popping sound and exhibited a refractory period (just like a real joint).” CHALLENGING ESTABLISHED SCIENCE MIKE STRAUS is a freelance writer based in Kelowna, British Columbia. 20 Canadian Chiropractor May 2017 Dr. Jacob Jaremko is a radiologist and associate professor in the University of Alberta’s Faculty of Medicine and a co-author of Kawchuk’s 2015 study. Jaremko notes that the 2015 study dis-proved a critical element of what was then the most widely accepted theory of joint cracking. During the 2015 study, Fryer cracked his knuckles while his hands were observed through a magnetic resonance imaging (MRI) machine. Jaremko and the rest of Kawchuk’s team recorded both the MRI images and the sounds produced during the experiment, and discovered a critical fact about joint cracking. “When we put the sounds and images beside each other,” Jaremko explains, “we saw there was www.canadianchiropractor.ca
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