Evaluation of radiolucency condition in total hip arthroplasty: a statistical comparison of the diagnostic capability of digitised image vs. conventional X-ray film.

This work analyses the diagnostic capability of radiographic images taken from patients with total hip arthroplasty and visualised on monitor. Images were obtained with digital acquisition of conventional X-ray films. The investigated pathology is the absence of direct contact between bone and prosthesis (radiolucency). Three senior orthopaedists defined the diagnostic "truth" on well-defined regions of interest on 22 conventional X-ray films of total hip arthroplasty, obtaining a total of 110 reference ratings. Films were digitised by use of an X-ray scanner. Four readers evaluated the X-ray images, applying conventional and monitor visualisation. To show any difference between ratings on film and ratings on monitor a sensitivity, specificity and accuracy study jointly with a receiver operating characteristics (ROC) study were performed for each reader and for all combined readings. The intra-observer reproducibility of the radiographic protocol was equal to 87% and the inter-observer one was in the range 85-92%. The sensitivity, specificity and accuracy study together with the ROC analysis did not show significant differences between the two evaluation modes. The evaluation of radiolucency from digitised X-ray films visualised on a monitor resulted statistically comparable with the conventional evaluation on X-ray films.