Correlation of malrotation deformity in distal radius fractures with radiographic analysis: cadaveric study

The radiographic parameters commonly used for evaluating distal radius fractures are radial length, palmar tilt, radial inclination, and articular congruity. Rotation of the distal fragment is not routinely evaluated after distal radius fractures. The purpose of this study was to define the appearance of distal fragment malrotation on conventional radiographs and to correlate varying degrees of malrotation with the corresponding radiographic findings.

Six distal radiuses from embalmed cadavers were cut and stabilized in 10 degrees, 20 degrees, and 30 degrees of pronated malrotation. Posteroanterior, lateral, and oblique (45 degrees pronated view) radiographs were taken and radiographic measurements were made of radial length, palmar tilt, radial inclination, and rotation.

With malrotation, the visible cortical width of the distal fragment mismatched the visible cortical width of the proximal fragment. This was most evident on the oblique view (p < .05) and measured 2.2 mm for 10 degrees of rotation (standard deviation [SD] 0.6), 3.4 mm for 20 degrees of rotation (SD 0.8), and 5.3 mm for 30 degrees of rotation (SD 2.2).

The radiographic parameter of rotation should be considered when evaluating distal radius fracture reduction. Malrotation is best seen on a 45 degrees oblique pronated radiographic view as a mismatch of the cortical width of the distal fragment compared with the cortical width of the proximal fragment. In the absence of radial shortening, a 5.3-mm mismatch is associated with 30 degrees of malrotation and is the upper limit of acceptability.