Education And Debate

ABC of Emergency Radiology: THE WRIST

BMJ 1994; 308 doi: http://dx.doi.org/10.1136/bmj.308.6926.464 (Published 12 February 1994) Cite this as: BMJ 1994;308:464
  1. D W Hodgkinson,
  2. N Kurdy,
  3. D A Nicholson,
  4. P A Driscoll

    The wrist is composed of eight bones arranged in a proximal row (scaphoid, lunate, triquetrum, and pisiform) and distal row (trapezium, trapezoid, capitate, and hamate). Each row functions as a separate unit. Three articulations make up the carpus (figs 1 and 2).

    FIG 1

    Normal posteroanterior radiograph of the wrist with line drawing showing anatomy.

    FIG 2

    Normal lateral radiograph of the wrist with line drawing showing anatomy.

    Radiocarpal joint - The distal radius articulates with the bones of the proximal carpal row (except the pisiform and triquetrum). This joint complex is supported by strong radiocarpal and intercarpal ligaments.

    Carpocarpal joints - The proximal carpal row articulates with the distal row. These articulations are also supported by strong intercarpal ligaments that can be damaged in isolation after wrist sprains or in combination with scaphoid fractures and carpal dislocations.

    Carpometacarpal joints - The distal carpal row articulates with the proximal end of the metacarpal bones. The finger carpometacarpal joints allow little movement compared with that of the thumb.

    The carpal bones are bound to each other by short intercarpal ligaments, such as the scapholunate and the triquetrolunate. The articulation of the distal radioulnar joint including the triangular fibrocartilage allows pronation and supination at the wrist joint.

    * Foreign bodies such as wood are radio - opaque and therefore not visible on standard radiography

    Development

    Primary ossification centres of the carpus begin to appear at 3 months of age, starting with the capitate and hamate. By the age 5-6 years all the carpal bones have visible ossification centres. The last bones to ossify are the scaphoid and trapezoid.

    Mechanisms of common injury

    Most injuries to the wrist are caused by a fall on the outstretched hand. This results in dorsiflexion of the hand and ulnar deviation of the hand together with supination of the carpus against a pronated forearm. The resultant …

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