X-RAY-FILM MEASUREMENTS FOR HEALED DISTAL RADIUS FRACTURES

In order to understand the effect of malunion on functional outcome, i t is essential that deformity be measured in a consistent manner. A st andardized method of measuring eight anatomic parameters at the distal radius was developed. By this method, six x-ray films of healed dista l radius fractures were subsequently measured by 16 raters. Rater agre ement was quantified by using the intraclass correlation coefficient. Tolerance limits were developed in order to estimate the expected marg in of error for each parameter. Parameters measured with high rater ag reement include ulnar variance, palmar tilt, and radial shift; however , even experienced clinicians did not readily agree on the size of ste p and gap deformity. Using the method of tolerance limits, one would e xpect that two randomly chosen clinicians measuring step and gap defor mity on a random x-ray film will differ by more than 3 mm at least 10% of the rime. Similarly, repeat step or gap measurements by the same o bserver are expected to differ by more than 2 mm at least 10% of the r ime. In view of our inability to measure deformity more accurately, th e concept of a specific relationship between a given degree of deformi ty and outcome must be questioned. Prospective research is needed in o rder to improve our understanding of the precise relationship between malunion and functional outcome.