A Morphometric Analysis of the Distal Radius: Implications for the Distal Radioulnar Joint

Background: The stability of the distal radioulnar joint (DRUJ) relies heavily on the osseous congruity of the ulnar (sigmoid) notch. Morphometric variations, particularly anterior-posterior asymmetry, significantly influence joint mechanics and implant design. This study aimed to evaluate the detailed morphometric parameters of the distal radius, specifically analyzing the dimensional asymmetry between the anterior and posterior aspects of the ulnar notch. Materials and Methods: A morphometric study was conducted on 54 dry adult human radii (27 right and 27 left) free of pathology. Using a digital Vernier caliper (0.01-mm precision), measurements were obtained for the anterior and posterior lengths of the ulnar notch, notch width, radial styloid length, and the dimensions of the inferior articular facet. Statistical analysis was performed using paired and independent t -tests. Results: The analysis revealed significant anteroposterior asymmetry. The posterior (dorsal) length of the ulnar notch was consistently greater than the anterior (volar) length. On the right, the mean posterior length (0.77 ± 0.18 cm) significantly exceeded the anterior length (0.46 ± 0.14 cm; P < 0.001). Left-sided specimens showed a similar pattern (0.58 vs. 0.45 cm). Conversely, the inferior articular facet was wider at its anterior margin. The mean radial styloid length was 1.16 cm (right) and 1.12 cm (left). Conclusion: The ulnar notch extends significantly further dorsally than volarly, likely to accommodate the dorsal radioulnar ligament and increase articular surface area. In contrast, the radiocarpal facet is wider anteriorly. These morphometric norms are critical for preoperative planning, radiographic interpretation, and designing anatomical plates that restore DRUJ congruity.