Displaced dorsal rim fragment in distal radius fracture: what is the size threshold for compromise?

This study aimed to explore the effect of displaced dorsal rim fragments under defined size threshold on the clinical outcome.

Forty patients with an acute distal radius fracture accompanied by a dorsal rim fragment comprising less than 10% of the radiocarpal articular surface were included in the study. The size of the dorsal rim fragment was measured by axial CT scans and three-dimensional (3D) CT scans, and the correlation between these two methods was analyzed to evaluate the reliability of axial CT scan measurements. Based on the displacement (> 2 mm) of dorsal rim fragments measured by sagittal CT scans, the patients were divided into two groups, namely the displaced group (17 patients) and the control group (23 patients). The radiographic parameters and wrist function at final follow-up were compared between the two groups.

Mean radiocarpal joint involvement of the included dorsal rim fragment was 8.6%±1.0% (range, 5.7–9.9%) assessed by axial CT scans. There was a strong correlation in the radiocarpal articular involvement of the dorsal rim fragment between axial CT scans and 3D CT models (correlation coefficient r = 0.819). Mean displacement of the dorsal rim fragment was 2.2 (2.1, 2.5) mm (range, 2.0–3.2) in the displaced group and 0.9 (0, 1.5) mm (range, 0–1.9) in the control group. There were no significant differences in any radiographic parameter and wrist function between the two groups.

For dorsal rim fragments comprising less than 10% of the radiocarpal articular surface in distal radius fracture, mild displacement does not significantly affect the recovery of wrist function.