Purpose: Internal fixation for distal radius fractures often relies on pre-contoured volar plates. Malrotation is a common issue in distal radius fractures and biomechanical studies suggest this can lead to radio-ulnar dysfunction. Despite this, the degree of rotation that exists at the distal radius has not been well examined. We aim to establish a new measurement to quantify the degree of rotation which is clinically relevant in designing and choosing a volar plating system. Method: CT scans of patients from the North Shore Hospital acute trauma list that presented with suspected carpal pathology were retrospectively analysed. The volar cortical torsion (VCT) was calculated at the distal aspect of the pronator fossa. This is of clinical importance as this also forms the safe boundary for placement of the plate. The point on the radius where the volar surface transitions from concave to convex was the reference point for the measurement. Measurements were taken independently by two observers. Results: The mean VCT was 4.9 degrees with a standard deviation of 2.8 degrees. There was strong correlation for interrater reliability. There was an intra-class correlation coefficient (ICC) of 0.96 (p<0.0001) and Bland-Altmann limits of agreement showed an average bias of -0.16 with limits of agreement from -1.82 to 1.50. There was also strong correlation for intrarater reliability with an ICC of 0.94 (p<0.0001) and Bland-Altmann limits of agreement having an average bias of -0.18 with limits of agreement from -0.07 to 0.42. Outcome: While there is variability within the population, our method shows the VCT can be reliably calculated. This can be useful when selecting a volar plate for internal fixation to prevent malrotation.