Abstract
Background Forearm rotation results in change in ulnar variance. Axial loading of the wrist
is required to maintain daily activities. Change in ulnar variance during axial loading
has not been investigated previously.
Purpose To measure the change in ulnar variance on axially loaded wrists.
Patients and Methods We examined 21 asymptomatic individuals and 24 patients with unilateral ulnar-sided
wrist pain. All patients underwent standard neutral posteroanterior wrist radiographs
without load and under axial loading on bilateral wrists. Axial loading was standardized
at 18.1 kgf using an analog weight scale. A magnetic resonance (MR) arthrogram was
obtained only in patients with ulnar-sided wrist pain. Beighton flexibility score
was recorded on healthy volunteers. Change in ulnar variance between 0 and 18.1 kgf
was compared for each wrist among all subjects. A correlation was sought between the
change in ulnar variance, MR arthrogram findings, and physical examination.
Results In individuals without wrist pain, on average, 0.4 mm increase in ulnar variance
was measured between 0 and 18.1 kgf. There was no difference between the dominant
and nondominant side. No correlation was found with increasing age. In contrast, patients
with ulnar-sided wrist pain displayed an average increase of 0.8 mm in ulnar variance.
Compared with the contralateral wrist, more than 1 mm increase in ulnar variance was
correlated with intra-articular pathologies including dorsoulnar ligament disruption,
central triangular fibrocartilage complex (TFCC) perforation, and foveal detachment.
Conclusion Compared with contralateral side, more than 1 mm increase in ulnar variance is suggestive
of longitudinal instability or TFCC pathology.
Level of Evidence Level II, diagnostic.
Keywords
ulnocarpal abutment - impingement - ulnar variance - TFCC - axial loading
