Radiographic Sagittal Tibio-Talar Offset in Ankle Arthrodesis-Accuracy and Reliability of Measurements.

Sophie Schieder,Elena Nemecek,Reinhard Windhager,Alexander Kolb,Madeleine Willegger,Reinhard Schuh

doi:10.3390/jcm9030801

Abstract

Radiographic outcome assessment of ankle arthrodesis (AA) requires accurate measurement techniques. This study aimed to identify the most reliable methods for sagittal tibio-talar alignment measurements with regard to the tibio-talar offset after AA. Lateral weight-bearing radiographs of 38 fused ankles were selected for retrospective review. The sagittal tibio-talar angle (STTA), the modified tibio-talar ratio (mT-T ratio) and the sagittal tibio-talar offset (tibCOR, procLAT) were measured by three independent observers. Intra- and interobserver correlation coefficients (ICC) and mean measurement differences were calculated to assess measurement reliability and accuracy. By defining the talar longitudinal axis as a line from the inferior aspect of the posterior tubercle of the talus to the most inferior aspect of the talar neck, STTA showed excellent (ICC 0.924; CI 95% 0.862–0.959) and mTT-ratio provided high (ICC 0.836; CI 95% 0.721–0.909) interobserver reliability, respectively. For tibio-talar offset measurement the tibCOR method showed superior reliability and better interobserver agreement compared to the procLAT technique. The STTA and a modified T-T ratio are recommended for future scientific radiographic measurements in AA.

Highlights

Multiplanar deformity in ankle arthritis is a common condition due to a high prevalence of posttraumatic arthritis [1,2]
Establishing accurate and reproducible radiographic measurement methods for the sagittal tibio-talar angle and offset in ankle arthrodesis is essential for evaluating the reconstruction of anatomical tibio-talar joint alignment
The inter- and intraobserver reliability of different proposed radiographic measurement methods for the sagittal tibio-talar angle (STTA) and the tibio-talar offset have been investigated for the first time

Summary

Introduction

Multiplanar deformity in ankle arthritis is a common condition due to a high prevalence of posttraumatic arthritis [1,2]. Ankle arthrodesis (AA) is still a worldwide commonly used operative procedure in end-stage disease [3,4,5,6]. In order to create a plantigrade and well-aligned AA, the coronal, axial, and sagittal tibio-talar alignment has to be addressed. The sagittal position of the talus relative to the tibial axis (tibio-talar offset) has to be taken into account. A posteriorly located talus shortens the length of the mid- and forefoot, which decreases the stance time on the foot during gait. An anteriorly located talus shortens the lever arm of the plantar flexors and increases the time needed to step over the foot [9]

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