Purpose <p>This study aimed to investigate the presence and morphological and morphometric characteristics of the distal radius’s external groove (EG) and bony ridge, which play a potential role in the pathogenesis and treatment difficulties of De Quervain’s tenosynovitis.</p> Methods <p>The osseous anatomy of the distal radius was analyzed in detail on a total of 103 dry bone specimens (49 left and 54 right) obtained from the Department of Anatomy, Istanbul University, Turkiye. The frequency and morphology of the EG were analyzed. The EGs were categorized as Type 1, Type 2, and Type 3 with two EGs, one EG with depth, and an additional EG without depth, respectively. Finally, flat areas without clear groove boundaries were classified as Type 4.</p> Results <p>The analyses showed variations in the morphology and dimensions of the EG and bony ridge. A total of 110 EGs were detected in 103 radii examined. Type 1, Type 2, Type 3 and Type 4 EGs were reported in 30 bones (30%), 38 bones (38%), 12 bones (12%) and 23 bones (23%), respectively. The depth of the EG of Type 1 was 0.26 <i>±</i> 0.23&#xa0;mm and 0.22 <i>±</i> 0.16&#xa0;mm on the lateral and medial sides, respectively. Also, the depth of the Type 2 was calculated as 0.49 <i>±</i> 0.37&#xa0;mm.</p> Conclusion <p>The osseous variations of the distal radius are critical anatomical factors contributing to the pathogenesis of De Quervain’s tenosynovitis and difficulties in the treatment process. It is essential to recognize these variations to improve diagnostic accuracy and optimize therapeutic interventions.</p>