Ulnar Variance in Scaphoid Fractures: Retrospective Analysis of 182 Cases.

Background: Literature provides little and controversial evidence regarding the influence of ulnar variance (UV) on the incidence of scaphoid fractures. The aim of this retrospective study was to assess UV in a large number of patients with acute scaphoid fracture in comparison to a control group of the same population.

Methods: During a two year period, 182 patients with acute scaphoid fractures (fracture group) and 182 ethnicity-, gender- and age-matched patients with wrist contusions (control group) were treated in three non-university hospitals. Using standardized digital wrist radiographs, UV values were measured by means of the method of perpendiculars by two independent examiners. The UV values of the fracture group were then compared to the UV values of the control group.

Results: Analyses of the agreement between the two raters resulted in a good to excellent inter-item correlation of 0.89, with a high intra-class coefficient of 0.93 (95% confidence interval: 0.87-0.95). Mean (SD) UV value was -0.82 mm (1.77) in the fracture group and 0.27 mm (1.44) in the control group. Paired sample t-test showed a significant difference between the two groups (p < 0.0001).

Conclusions: According to this study, patients with scaphoid fractures are significantly more likely to show a negative UV than matched patients with wrist contusions.