Validity and Reliability of Image Intensifier Articular Step-off and Gap Measurements for Distal Radius Fractures Using a Cadaveric Model

Objectives. The purpose of this study was to determine the accuracy and reproducibility of image intensifier(fluoroscopic) measurements of gap and step-off displacements on the articular surface of the distal radius using a standard cadaver osteotomy fracture model. 
Methods. Fourteen orthopedic residents were randomly assigned using the fish bowl method to measure the gap and step-off displacements in cadaveric fluoroscopic images using a digital caliper. Each physician was randomly assigned the images where they examined the images twice and the average taken using a standard technique. The interobserver and intra-observer reliability were calculated using the intraclass correlation coefficient (ICC). Rank Sum test was used to evaluate the validity of measurements.Results. The results of the study showed that there was no significant difference between the cadaveric andmeasured step-off and gap displacements. Intraclass correlation coefficient scores showed moderate (0.41) to perfect (1.0) agreement.Conclusion. The study showed that fluoroscopy can aid in the interpretation of gap and step-off displacements in acute distal radius fractures.