THE EFFECTS OF FOREARM ROTATION ON THREE WRIST MEASUREMENTS: RADIAL INCLINATION, RADIAL HEIGHT AND PALMAR TILT

Abstract

The purpose of this study was to evaluate and quantify the effects of forearm rotation on radial inclination, radial height and palmar tilt. Seventeen arms, nine cadaveric and eight volunteer, were examined using a radiolucent device that allowed for the controlled rotation of each arm. Lateral and posterior-anterior X-rays were taken at 5 degrees increments which were then measured by two physicians using standardised protocol. The results revealed that all three measurements were significantly affected by forearm rotation with forearm supination increasing the apparent measurements and forearm pronation decreasing the apparent measurements. This relationship was well characterised by linear trend modelling such that forearm pronation of 10 degrees decreased the apparent radial inclination, radial height and palmar tilt by 2.8 degrees , 1.6 mm and 4.4 degrees , respectively. This study demonstrates that forearm rotation is an important factor in the accurate evaluation of wrist measurements, and that slight rotation of the wrist during radiographic imaging may significantly alter management decisions given established surgical criteria.