Defining the Tibiotalar Station in the Coronal and Sagittal Planes: A Computed Tomography Analysis of 132 Ankles.

INTRODUCTION

Restoring alignment of complex tibiotalar fractures is challenging when anatomical landmarks are obscured. This study defined the tibiotalar station (TS) using CT and evaluated its correlation with radiographs.

METHODS

Patients (≥18 years) with a normal lower extremity CT at two level 1 trauma centers between May 2022 and May 2024 were identified. A secondary cohort had intraoperative fluoroscopic ankle imaging. The TS (reported as median [interquartile range]) was defined as the shortest distance from the tibial axis to the center of the talus in the coronal and sagittal planes on CT, radiographs, and fluoroscopy. In addition, the distance from the tibial axis to the lateral talar process in the sagittal plane was measured on CT and fluoroscopy. Negative values indicated the tibial axis was lateral or posterior. Correlations between CT and radiographic measurements were assessed using Pearson correlation coefficients. Interobserver reliability was evaluated with intraclass correlation coefficients.

RESULTS

The primary cohort included 132 patients (median age 66 years, 50% female); 21 had ipsilateral normal ankle radiographs. On CT, the tibial axis intersected the talus -0.68 mm (lateral) to its center and -2.05 mm (posterior). Correlations between CT and radiographic measurements were strong (coronal, r = 0.82; sagittal, r = 0.70). On fluoroscopy, the tibial axis intersected the talus -0.45 mm (lateral) to its center and -1.15 mm (posterior). The tibial axis was -4.45 mm (posterior) to the lateral talar process on CT and -3.55 mm on fluoroscopy. Interobserver reliability ranged from good to excellent across all measurements.

CONCLUSION

The TS is a reliable metric for assessing tibiotalar alignment, with the tibial axis intersecting the talus slightly lateral and posterior to its center. The lateral talar process also serves as a useful reference for assessing sagittal alignment. These findings can help orthopaedic surgeons restore tibiotalar alignment during external fixation, fracture fixation, and arthrodesis.

LEVEL OF EVIDENCE: Diagnostic level III.