Evaluation of Ulnar Setting of Volar Locking Plates for Distal Radius Fractures Using Modified Skyline View

PURPOSE: Volar lunate facet fragments in distal radius fractures are located at the center of the load in the wrist joint and, therefore, should be properly supported by the distal ulnar setting of volar locking plates to obtain better postoperative outcomes. This study evaluated the usefulness of the modified skyline view (MSV) in intraoperative fluoroscopy for the ulnar setting of volar locking plates by comparing it with that of the anteroposterior view (APV). METHODS: Sixty-five patients with distal radius fractures who underwent open reduction and plate fixation as well as follow-up intraoperative fluoroscopy and postoperative computed tomography (CT) at our institution between April 2019 and March 2022 were included. The distance between the ulnar edge of the plate and the distal radius (d-value) was measured retrospectively using intraoperative fluoroscopy (distance measured from MSV and distance measured from APV) or postoperative CT (distance measured using postoperative CT). The distance measured from MSV and that measured from APV were compared with those measured using CT as the true values. Each measurement was performed twice by 2 examiners at an interval of 1 month. The comparison scores were evaluated using the intraclass correlation coefficient. RESULTS: The distance measured from MSV showed a difference of 0.6 ± 0.5 mm from that measured using CT, which was significantly smaller than that measured from APV (1.2 ± 0.9 mm; P < .001). Neither postoperative volar subluxation nor dislocation of bone fragments was found during the study period. Both intraclass correlation coefficient (1,1) and intraclass correlation coefficient (2,1) reliabilities were substantial to almost perfect. CONCLUSIONS: Modified skyline view is an effective and versatile imaging method for estimating the ulnar setting of volar locking plates; it provides measurements more similar to those provided by postoperative CT compared with APV. The use of MSV may reduce postoperative complications, such as volar subluxation and dislocation of bone fragments, especially in cases with volar lunate facet fragments in which the ulnar setting of the plate is significant. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic III.