Kienböck's disease--the influence of arthrosis on ulnar variance measurements

The individual difference in ulnar variance measurements between diseased and unaffected wrists in 38 patients with unilateral Kienböck's disease was determined and related to the degree of arthrosis in the affected wrists. In patients without arthrosis there was no difference in measurements. With increasing arthrosis there was a progressive increase of patients with individual difference in ulnar variance measurements: up to 50% in those with severe arthrosis. Where a difference in ulnar variance was encountered, the wrist with Kienböck's disease represented the more negative value in 90%. It is concluded that over-representation of the so-called "ulnar minus variant" in Kienböck's disease is based on osteo-arthritic changes in the wrist, resulting in a pseudo-lengthening of the distal radius, and that this is therefore a consequence of the disease. The "ulnar minus variant" seems to have no bearing on the cause of Kienböck's disease.