Imaging of Distal Radioulnar Joint Focused on Four-dimensional Computed Tomography: Toward a New Imaging Standard?

The distal radioulnar joint is essential for forearm rotation and wrist stability. Instability of the distal radioulnar joint, often resulting from trauma, ligamentous injury, or degeneration, can lead to pain, functional impairment, and progressive joint damage. Accurate diagnosis relies on a thorough imaging assessment due to the complex joint anatomy, especially the triangular fibrocartilage complex. Standard radiographs are useful to evaluate bone alignment but have limited soft tissue sensitivity. Ultrasound provides dynamic real-time assessment of superficial structures, although it is operator dependent. Computed tomography offers excellent spatial resolution for bony abnormalities and joint congruity, with a static and pseudo-dynamic approach, considered the gold standard. Magnetic resonance imaging is the reference standard for soft tissue evaluation, particularly the triangular fibrocartilage complex and surrounding ligaments. Emerging dynamic imaging techniques, including real-time magnetic resonance imaging and four-dimensional computed tomography, allow visualization of joint kinematics and detection of subtle instabilities not seen on static images. This review outlines the role of each modality in assessing distal radioulnar joint instability.