Dorsal Screw Protrusion Identification Following Volar Plating for a Distal Radial Fracture: Comparing Skyline View Versus Intraoperative 3D Fluoroscopy

This study investigates the efficacy of intraoperative 3D fluoroscopy compared to skyline view for detecting dorsal cortex screw protrusion in volar locking plating (VLP) procedures for unstable distal radius intra-articular fractures (DRF). This is assessed through postoperative CT scans, addressing the limitations of previous methods in evaluating screw penetration accurately.

The study utilized the ICUC database, a prospective cohort of patients with surgically treated DRF, to select cases with available imaging from skyline views, intraoperative 3D fluoroscopy, and postoperative CT scans. The evaluation included determining if screws were penetrated the dorsal cortex or not. Intraoperative 3D fluoroscopy's coronal, axial, and sagittal views identified dorsal screw protrusions, confirmed by postoperative CT. Cohen’s Kappa was calculated using STATA 15.1 to assess the interrater reliability of intraoperative imaging compared to postoperative CT.

Twenty-one intra-articular DRFs were included in the study. The agreement between skyline view and postoperative CT was moderate agreement, with a kappa value of 0.492 (95% CI: 0.255 to 0.719, N=72), identifying three uncertain, 54 shorter screws and 15 screw penetrations. Intraoperative 3D fluoroscopy demonstrated almost perfect agreement with postoperative CT, with a kappa of 0.832 (95% CI: 0.673 to 0.991, N=72), identifying 56 shorter screws, 16 screw penetrations. The sensitivity and specificity of intraoperative 3D fluoroscopy in detecting dorsal screw protrusion are 81.2% and 98.2%, respectively. In comparison, the skyline view has a sensitivity of 60.0% and a specificity of 91.2%.

The accuracy of the skyline view depends on using the appropriate fluoroscopic modality, wrist position, and the relationship with the imaging source. The skyline views offer only moderate evaluation of dorsal screw protrusion, whereas 3D fluoroscopy demonstrates nearly perfect agreement. Given its high reliability and potential to reduce cumulative radiation exposure for surgeons seeking optimal skyline views, 3D fluoroscopy allows surgeons to remain away from the field during 3D scanning. This highlights 3D fluoroscopy as a valuable modality.

Keywords: distal radius fracture; 3D fluoroscopy; skyline view; dorsal screw protrusion; volar locking plate