ORIENTATION SELECTIVITY OF FOOT RADIOGRAPHS ON INTERPRETATION SKILLS

Abstract

Plain radiographs remain important diagnostic tools in the initial assessment of patients with suspected fractures or dislocations of the foot. Analysis of foot radiograph is a difficult task even in the hands of experts, which is misinterpreted in 2.1% cases. Human visual system is more sensitive to horizontal and vertical stimuli & cardinal orientations (Vertical and Horizontal) perceived more accurately than others. Any absolute judgement task is subject to two types of error: Systematic error and random error. Hence a system of assessment with very high random error of measurement is unlikely to be a reliable assessment method. We tried to find out the influence of experience and orientation on interpretation of foot radiograph.

AP and lateral radiograph from 25 patients who had some form of foot injury were included in this study. The radiographs were first analysed by an experienced foot surgeons for fractures with clinical details to facilitate the identification of the fracture & then presented in two different orientations (vertical and horizontal) to 38 orthopaedics surgeons of different grades and blinded about the nature of the study. We used Kappa analysis & logistic regression to find out the influence of orientation and experience on interpretation skills.

Overall agreement between the foot surgeon and other observers was 0.4. Overall agreement between the observers and the foot surgeon, in the vertical orientation, was.43 and in the horizontal orientation was.32. When experience was taken into consideration agreement between orthopaedics surgeons and the foot surgeon was.416 and agreement between registrar and foot surgeon was.367 and the SHO and foot surgeon was.369. We found that the regression coefficient for horizontal orientation was −.302 and the regression coefficient for the experience was 0.067. Hence horizontal orientation increases the chance of misinterpreting a foot radiograph by 30.2% and with increasing experience the chance of correctly identifying the fracture increases by 6.7%. From this study it is evident with all the other variables like experience, quality and adequacy of radiographs optimised, orientation of the foot radiograph alone can significantly affect the interpretation skills of the observer.