Scaphoid translation measurements in normal wrists.

The purpose of this study was to establish a normal measure of scaphoid position in the radioulnar plane in standard neutral, radial and ulnar deviation posteroanterior radiographs. This measurement may allow indirect evaluation of the radiocarpal ligaments and comparison between normal and pathologic states (following radius fractures, perilunate dislocations). Measurements were trialed on 74 normal wrist radiographs and 25 cadaver wrists. We evaluated the distance between the radial styloid and the scaphoid and corresponding scaphoid width. The ratio of distance/width at the mid styloid level (0.35, imprecision SD = 0.1) had the lowest random error and is therefore the most precise measurement of true scaphoid translation. This measurement is independent of scapholunate ligament integrity and may provide a better assessment of the radiocarpal component of ulnar translational instability. Abnormal movement of the scaphoid in the radioscaphoid joint likely reflects ligamentous injury. Identifying and addressing these injuries may prevent the development of arthritis.