Post-traumatic deformities in the forearm bones have direct consequences for rotation of the forearm whose full prono-supination is based on the radius-ulna congruency. Sophisticated software give us today the possibility to convert highly defined computed tomography scans into three-dimensional digital models that offer the substrate to virtually analyse and plan osteotomy site, osteotomy angles and to simulate fragment reduction to closely mirror either a healthy contralateral forearm or a statistical model. To achieve the planned correction in surgery, patient specific drill- and cutting guides are then virtually designed and 3D-printed. Primary indication for 3D-virtual surgical planning is the malunion of one or both bones in the forearm in patients with symptoms such as functional loss of rotation and/or pain/discomfort or recurrent dislocations in the proximal- or distal radioulnar joints.