Magnetic resonance imaging (MRI) validation of a novel method of assessing Distal Radial Fracture (DRF) reduction using the hypothesised constant relationship between the dorsal radial cortex (DC) and the superior pole of the lunate (SL).

MRI scans of 28 normal wrists were examined. Scans included the distal third of the radius to the proximal carpal row. Beginning 5cm proximal to the distal radius articular surface, a line was superimposed upon the DC extending distally through the metaphyseal flare.

Lunate height (LH) and distance from the DC line to the SL (DC-SL) were measured at 5-degree rotational increments around the radial shaft central axis to a total of 30 degrees of supination and pronation (S+P). The DC-SL/LH ratio was compared to 0 degrees (anatomical lateral) using the two-tailed paired student t-test.

There was no significant difference in DC-SL:LH between 0 degrees of rotation and any 5-degree increment up to 30 degrees of S+P (lowest p=0.075). The DC line lay consistently dorsal to the SL.

A constant DC-SL relationship exists with up to 30 degrees of S+P. This reference can be quickly and accurately used to assess DRF reduction in poorly-taken films with malrotation up to 30 degrees from anatomical lateral. Research comparing DC-SL distance with volar tilt to assess DRF reduction is needed.