The Distal Radio-Ulnar Joint: Functional Anatomy, Biomechanics, Instability and Management

Abstract

For most surgeons, the distal end of the radius is viewed as the anatomic foundation of the wrist joint. The distal end of radius, about 2 cm proximal to the radiocarpal joint at the metaphyseal fl are, is uniquely designed to transmit axial load and provide mobility [1]. The distal articular surface of the radius is biconcave and triangular. The apex of the triangle points towards the radial styloid process, and the base forms the sigmoid notch that articulates with distal end of the ulna. Two distinct concave facets are found on the articular surface (Fig. 1). These facets articulate with the scaphoid and the lunate of the carpus. The articular surface slopes in an ulnar and palmar direction. Although the carpus tends to slide in this direction, this is resisted by the intracapsular and interosseous carpal ligaments. The DRUJ is a di-athrodial joint, comprised of the triangular fi brocartilage complex (TFCC), ligament complex and oblique fi bres of the distal interosseous membrane. It is classifi ed as a uni-axial synovial pivot joint between the convex head of the ulna and concave ulnar notch of the radius.