gms | German Medical Science

Hypothesis: the distal fracture fragment in distal radius (wrist) fractures very commonly rotates as well as shortens and angulates.

Aim: To assess the frequency and degree of rotation of the distal fracture fragment on CT scans.

Methods: Retrospective radiological assessment of 85 CT scans of the distal radius: 35 following a fracture and 50 normal radii. A simple method for measuring rotation of the distal radius relative to the diaphysis using routine CT scans was developed and applied.

Mann-Whitney analysis was used to identify differences in radial rotation between fractures and controls. Intra- and interobserver reliability were analysed using intraclass correlation coefficients and Bland-Altman plots.

Results and Conclusions: The distal fracture fragment could rotate into pronation or supination relative to the diaphysis, both normally and following a fracture. The median radial rotation angle was -1° (pronation, range -15-4°) in the control group compared to -3° (pronation, range -24 - 31°) in the fracture group. The absolute rotation angle was significantly greater in the fracture group (median 10°, range 0-31° vs to 3°, range 0-15°; U = 291.50, Z= -5.21, p < 0.001) and outside the "normal range" of this study in 26 cases indicating that at least 75% had rotated appreciably following injury.

Both intra and interobserver reliability was very good with intraclass correlation coefficients of 0.99 and 0.98 respectively.

Malrotation of the distal radius is common following a distal radius fracture. Malrotation of the distal fracture fragment has been shown to affect DRUJ function. Despite this rotational deformity is often overlooked in clinical practice. The simplified method described in this study is both easy to use in routine clinical practice and reliable. Measuring radial rotation angle using such a method may be an important consideration when planning primary treatment and corrective osteotomy for patients with distal radial malunion.