Ultrasound assessment of carpal tunnel syndrome and DRUJ instability

It has been expected that ultrasound demand in daily medical care will continue to increase. In this presentation, our attempts for ultrasound assessment of carpal tunnel syndrome and distal radio-ulnar joint (DRUJ) instability will be introduced. 

 For the first topic, recent ultrasound assessment of carpal tunnel syndrome will be discussed. The main advantages of ultrasonography are that it is simple, quick, non-invasive, and economical. Another advantage is that tissue dynamics can be observed with real-time imaging. It has been shown that ultrasonic examination can provide similar diagnostic accuracy as nerve conduction study in the diagnosis of carpal tunnel syndrome. Ultrasonography in carpal tunnel syndrome shows an enlarged median nerve and edema around flexor tendons in proximal carpal tunnel. In addition, with the introduction of technologies such as ultrasonic elastography, speckle tracking and deep learning, it has become possible to quantify dynamics and material property changes of nerves, tendons, and their surrounding structures. 

For the second topic, we attempted to evaluate the differences in the force-displacement relationship of the DRUJ between patients with triangular fibrocartilage complex (TFCC) injury and healthy controls using force-monitor ultrasonography. Cyclic compression was applied to the dorsal surface of the ulnar head. Distance between the dorsal surface of the distal radius and ulnar head at the DRUJ level was measured in the initial and pressed-down positions. Changes in radioulnar displacement, applied force, and displacement-to-force ratio were measured. The radioulnar displacement and displacement-to-force ratio were significantly larger in the affected wrists than in the unaffected wrists. The affected/unaffected side ratio of radioulnar displacement and displacement-to-force ratio were significantly larger in the TFCC injury patients than in the controls. Assessing the instability with force-monitor ultrasonography may help to identify DRUJ disorders.