Test your knowledge: radiocarpal joint.
Question:
This drawing shows us some carpalia, the radius and the ulna, and some parallel lines. What do these lines mean? And do you see which anatomic variation is drawn in the picture? Clue: this particular variation is associated with scapholunate instability and triangular fibrocartilage tears – it jeopardizes the weight bearing function of the wrist.
See the answer of this question below the image!
Answer:
Ulnar variance is described as being zero, minus, or plus. In the picture you can see a positive ulnar variance. This is measured by using the method of perpendiculars. Straight lines are drawn, perpendicular to the long axis of the radius and ulna. One line is drawn along the ulnar articular surface; the other is drawn along the articular surface of the radius. The distance between these lines determined ulnar positive or negative variance. When the ulnar surface is more distal to radial there is an ‘ulnar positive variance’ - see also: Keats & Sistrom, Atlas of Radiologic Measurement, 7th ed. (2001) 186-99.
(Image by: Marc Schmitz)