Visualization of Joint Cavitation
Written by Editor   
Thursday, May 14, 2015 12:00 AM

In this study, ten metacarpophalangeal joints were studied by inserting the finger of interest into a flexible tube tightened around a length of cable used to provide long-axis traction. Before and after traction, static 3D T1-weighted magnetic resonance images were acquired. During traction, rapid cine magnetic resonance images were obtained from the joint midline at a rate of 3.2 frames per second until the cracking event occurred. As traction forces increased, real-time cine magnetic resonance imaging demonstrated rapid cavity inception at the time of joint separation and sound production after which the resulting cavity remained visible.

Results offer direct experimental evidence that joint cracking is associated with cavity inception rather than collapse of a pre-existing bubble. This is the first in-vivo macroscopic demonstration and provides a new theoretical framework to investigate health outcomes associated with joint cracking.

Sounds emitted from human synovial joints vary in their origin. Joint sounds that occur repeatedly with ongoing joint motion arise typically when anatomic structures rub past one another. In contrast, “cracking” sounds require time to pass before they can be repeated despite ongoing joint motion. 


Before cracking

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The same hand following cracking.  Note the dark, interarticular void (yellow arrow).