Detecting dorsal screw penetration following volar plate fixation of the distal radius – A validation study in a saw bone model

Background The fluoroscopic detection of dorsal screw protrusion following volar locking plate fixation of distal radius fractures remains difficult. The carpal shoot through view has recently been reported to result in a 17% intra-operative screw exchange rate. The aim of the current study was to assess the sensitivity of the carpal shoot through view in comparison to conventional fluoroscopic views for detecting dorsal cortical and distal radio-ulnar joint screw penetration. Methods A volar locking plate was applied to a saw bone model and fluoroscopic views taken with the distal screws inserted flush or protruding by two full screw threads. Images were then shown to 10 orthopaedic surgeons who were asked to identify excessively long screws. Results The CST view demonstrated the greatest sensitivity for detection of dorsal screw penetration (78%). Its inter-observer reliability was 0.66 (substantial agreement) and intra-observer reliability 0.86 (near perfect agreement). The dorsal skyline had a sensitivity of 51%; the elevated lateral view had a sensitivity of only 16%. Conclusions The current study confirms that the elevated lateral view cannot be relied upon alone for the detection of dorsal screw penetration. The CST view is a valid technique demonstrating the greatest sensitivity in comparison to established intra-operative views.