Rotational Anatomy of the Radius and Ulna: Surgical Implications

Purpose: The rotational anatomy of the forearm bones is not well defined. This study aims to further the understanding of the torsion of the radius and ulna to better guide treatment. Methods: Computed tomography images of 98 cadaveric forearms were obtained and 3-dimensional models of the radius and ulna were generated and analyzed. The rotation of the radius was evaluated by comparing the orientation of the distal radius central axis (DRCA) with the volar cortex of the distal radius (DR) and biceps tuberosity (BT). The rotation of the ulna was evaluated by assessing the orientation of the ulnar head with respect to the proximal ulna. Results: The DR volar cortex pronates from distal to proximal. The BT was 43.8 degrees +/- 16.9 degrees supinated from the DRCA (range, 2.7 degrees-86.5 degrees). The mean difference in rotation between contralateral biceps tuberosities was 7.0 degrees +/- 7.1 degrees. The volar cortex of the DR was 12.6 degrees +/- 5.4 degrees supinated compared with the DRCA. The ulnar head was pronated 8.4 degrees +/- 14.9 degrees with respect to the greater sigmoid notch (range, 50.3 degrees pronation-22.0 degrees supination). Conclusions: The BT has a variable orientation relative to the DR, but it is generally located anteromedially in a supinated arm or 136 degrees opposite the radial styloid. Understanding the rotational anatomy of the radius and ulna can play an important role in surgical planning and implant design. The rotational anatomy of the radius and ulna varies significantly between individuals, but is similar in contralateral limbs. Copyright (C) 2020 by the American Society for Surgery of the Hand. All rights reserved.