Measuring ulnar variance: a comparison of techniques.

This study compared three commonly used methods of measuring ulnar variance. The comparison included the project- a-line technique (A), the method of concentric circles (B), and the method of perpendiculars (C). Specific features studied were variations in results generated by each technique as well as the interobserver and intraobserver reliability for each technique. The only significant difference among techniques was between techniques A and B (p = 0.0224), where mean A values were more positive than mean B values. Observers were found to differ significantly (p = 0.0092) independent of technique. All methods studied were highly reliable, although the method of perpendiculars was most reliable for both interobserver (reliability = 0.9801) and intraobserver (reliability = 0.9719) reliability. This study shows that the clinician may choose whichever technique he prefers when measuring ulnar variance.