Validity of fluoroscopic methods along the transsyndesmotic axis: A cadaveric study.

Abstract

Alignment along the transsyndesmotic (TS) axis is necessary to fix syndesmotic diastasis associated with ankle fractures. Fluoroscopic clamp techniques for the tibiofibular joint along the TS axis include the center-center (CC), talar dome lateral (TL), and incisura tangent (IT) methods. However, whether the clamp placement along the TS axis is feasible under fluoroscopy and the effects of metal artefacts from fracture fixation remain unclear. The purpose of this study was to clarify the differences from the TS axis using three methods under fluoroscopy on a cadaver and to compare the differences from the TS axis before and after implant placement for each method. Ten fresh-frozen cadaveric feet were used in this study. We used three methods and determined the interaxis angle and distance as the differences from the TS axis. Furthermore, implant placement was made in cadaveric feet, and these differences were evaluated using the three methods. The differences obtained by the three methods were compared using one-way repeated measures analysis of variance. Paired t-tests were used to compare the differences before and after implant placement. Both the interaxis angle and distance showed significant differences among the three fluoroscopic methods, irrespective of implant placement (p < 0.001). The CC method demonstrated pronounced internal rotation and posterior displacement relative to the TS axis. In contrast, both the TL and IT methods demonstrated minimal angular and translational deviations. Post-hoc analyses confirmed that both TL and IT methods were significantly closer to the TS axis than the CC method for both parameters, whereas no significant differences were observed between the TL and IT methods (p < 0.001). Implant placement did not significantly affect the interaxis angle or distance for any of the three methods (p > 0.05). Among the fluoroscopic methods, the TL and IT methods allowed clamping along the TS axis. Additionally, implant placement by any of the three methods had no effect on the interaxis angle or distance. The TL and IT methods may help reduce iatrogenic malreduction.