ABC of emergency radiology. The hand.

Abstract

Injuries to the hand and wrist account for about 15% of attendances at accident and emergency departments. The hand and wrist are complex structures and injury to just one small component can result in appreciable loss of function. Fortunately if the injury is identified early and managed appropriately function can be fully restored. The 14 phalanges and five metacarpals in each hand consist of a head, a body, and a base. Collateral ligaments extend from the lateral margins of the head of each metacarpal bone and phalanx (except the terminal phalanx) across the appropriate joint space to insert on the lateral margin of the base of the apposing phalanx. The volar aspect of the interphalangeal and metacarpophalangeal joint capsule is thickened and forms a dense fibrous structure called the volar plate. Sesamoid bones may be found on the palmar surface of the hand. The two commonest are in the tendons of the thumb in the two heads of the flexor pollicis brevis at the metacarpophalangeal joint (fig 1). The other sesamoid bones of the hand are usually found at the metacarpophalangeal portion of the volar plate. Sideways movement of the thumb metacarpophalangeal joint is prevented by strong ulnar and radial collateral ligaments (fig 9). FIG 1 Posteroanterior radiograph and line drawing of normal hand. Secondary ossification centres (epiphyses) in the metacarpals and phalanges of the hand appear at the age of 2-3 years, and the growth plate normally closes at puberty. Skeletal age up to puberty can be judged accurately from hand and wrist radiographs as the sequence of development is age specific. FIG 2 Collateral ligaments and volar plate of the proximal interphalangeal joint. Mechanism of Common injuries These are commonly produced by a crush injury and may be associated with severe trauma to the soft tissue (including the nail bed and …