In +2.5mm of ulnar variance 60% of load goes to radius while 40% goes though ulna.
It leads to ulnar sided wrist pain from increased impact stress on the lunate and triquetrum.
associated conditions include
Ulnar impaction syndrome
SLD
TFCC tears
Lunotriquetral ligament tears
This X ray shows :
In -2.5mm of ulnar variance, 95% of load goes through radius and 5% of load goes through ulna
It is commonly associated with Kienbock’s disease
Imaging
Method to determine ulnar variance
requires PA radiograph w/ wrist in neutral supination/pronation and zero rotation
from the PA view draw two lines one tangential to the articular surface of the ulna and perpendicular to its shaft
the other tangential to the lunate fossa of the radius and perpendicular to its shaft.
measure the distance between these two lines.
If the ulnar tangent is distal to the radial tangent there is positive ulnar variance, if it’s proximal there is negative ulnar variance. Normal is 0mm.
