The association of Kienbock's disease and ulnar variance in the Iranian population.

We retrospectively determined the distribution of ulnar variance in 60 patients with Kienböck's disease. We also measured the ulnar variances in 400 standard wrist radiographs in the normal adult population. The mean ulnar variance of the Kienböck's group was -1.1 mm (SD 1.7) and the mean ulnar variance of the general population was +0.7 (SD 1.5), which was significantly different. In the Kienböck's disease group there were 38 (63%) with ulnar negative, 16 (27%) neutral and six (10%) with ulnar positive variance. The preponderance of ulnar negative variance was statistically significant. There was an association between ulnar negative variance and the development of Kienböck's disease in this study.