Capsule of the Distal Radioulnar Joint, Posterior View

Description

Posterior to the distal forearm, the capsule of the distal radioulnar joint spans between the ulnar notch of the distal radius laterally and the head of the ulna medially, forming a fibrous sleeve around the synovial articulation just proximal to the ulnar styloid. Dorsal carpal contours sit distal to the capsule, with the proximal carpal row aligned beneath the radius, while the metacarpals and phalanges extend distally into the hand. Bony landmarks dominate. The spatial relationship emphasizes how the distal radioulnar joint sits ulnar to the radiocarpal joint yet functionally couples forearm rotation to wrist mechanics. A posterior angle matters because dorsal capsular thickening blends with the dorsal radioulnar ligament portion of the triangular fibrocartilage complex (TFCC), a frequent pain generator after a fall onto an outstretched hand with forced pronation or supination. Tears or attenuation here can produce distal radioulnar joint instability, classically worsening with the piano-key test at the ulnar head and with resisted pronation. Hand surgeons also reference this anatomy during arthroscopic TFCC evaluation and when planning dorsal approaches for DRUJ capsulorrhaphy, where staying oriented to the ulnar styloid and dorsal rim of the sigmoid notch reduces dissection drift. Orthopaedic and hand anatomy courses can pair this plate with kinematics teaching on pronation and supination, linking the capsule to the radius rotating around the relatively fixed ulna at the wrist. It also fits well in surgical atlases, exam prep material on TFCC injury patterns, and patient education sheets explaining ulnar-sided wrist pain after trauma. Anatomical accuracy verified by SciePro's Medical Advisory Board.