Computerized analysis of radiographs in Colles' fractures

Several radiographic parameters correlate with clinical outcome in distal radius fractures. This study describes a new, computerized routine that automatically defines the longitudinal axis of the radius, deriving the radial tilt, radial width, and radial height on anteroposterior radiographs of the wrist. The intraobserver and interobserver variability is reported in a series of 33 anteroposterior radiographs of the wrist. An edge-finding filter is used to determine accurately the cortices in several lines of each image. The midpoints between these two edges are used to determine the best-fit line, thereby defining the longitudinal axis of the bone. The operator marks the tip of the radial styloid and the lunate angle of the radius at the distal radioulnar joint. Radial shortening, widening, and loss of angle are calculated. The 33 radiographs were measured twice by two independent observers, and 12 sets of paired readings were analyzed using the two-tailed paired t test. The mean difference between readings was reduced to a fraction of degree or millimeter, virtually eliminating the intraobserver and interobserver errors. Thus, the current study shows the computer is a reliable and effective instrument for measuring radiographs. The computer-aided system of measurements can be extended to prostheses, fractures, and to other orthopaedic measurements.