Comparison of three dimensional and radiographic measurements in the analysis of distal radius malunion.

To estimate the accuracy of radiographic deformity evaluation for distal radius malunion, we compared the results obtained from radiographic measurements (palmar tilt, radial angle, and ulnar variance) with those from the three-dimensional (3D) method using computer bone models in 20 dorsally tilted malunions. Dorsal tilt deformity, radial tilt deformity, and shortening deformity were calculated using the unaffected side as a reference. The 3D method showed a slightly lower value for dorsal tilt deformity than the radiographic evaluation, but the difference was < 10° in all cases. In patients with dorsal tilt ≥ 40°, notable differences in radial tilt evaluation were observed between the two methods compared with patients with less dorsal tilt. The 3D shortening showed positive correlations with radiographic evaluation, but a discrepancy of ≥ 2 mm was observed in eight cases. Palmar tilt is reliable for surgical planning, but radial angle and ulnar variance may be less accurate than previously thought.