Accuracy of detecting screw penetration of the radiocarpal joint following volar plating using plain radiographs versus computed tomography.

We compared standard and specialized plain radiographs with computed tomography (CT) for their ability to detect screw penetration of the articular surface of the distal radius in volar plating. Eight human cadaveric specimens were implanted with a fixed angle volar plate and 5 screws. Two groups were evaluated: (1) no articular screw penetration or (2) intra-articular screw penetration. Radiographs were obtained of each specimen. CT using 0.4 mm thickness slices were obtained and images were reconstructed in the sagittal and coronal planes. The radiographs and CTs were evaluated based on whether or not articular penetration occurred. The sensitivity, specificity, and accuracy of each radiographic modality were evaluated. CT was found to be much more sensitive and specific in detecting screw penetration than plain radiographs. The kappa (κ) statistic demonstrated "almost perfect interobserver agreement" based on CT readings, but only "substantial interobserver agreement based on plain radiographs." CT is more sensitive and specific and achieves a higher κ statistic than plain radiographs in detecting radiocarpal screw penetration after volar plating. CT should be used in detecting screw penetration when there is suspicion for radiocarpal joint penetration.