Evaluation of Syndesmosis Reduction on CT Scan

Abstract

Background: Computed tomography (CT) imaging has traditionally been considered the gold standard for evaluation of syndesmostic reduction, but there is no uniformly accepted method to assess reduction. The aim of this study was to evaluate the intra- and interobserver reliability of published measurement techniques for evaluation of syndesmotic reduction on weightbearing CT scan (WBCT) in hopes of determining which method is best. Methods: Medical records were reviewed to identify patients who underwent operative stabilization of unilateral syndesmotic injuries. Exclusion criteria included patients younger than 18 years, ipsilateral fractures extending to the tibial plafond, any contralateral ankle fracture or syndesmotic injury, and body mass index greater than 40 kg/m2. Twenty eligible patients underwent WBCT evaluation of both ankles at an average of 3 years after syndesmotic fixation. The anatomic accuracy of syndesmotic reduction was evaluated by 2 observers using axial CT images at a level 1 cm proximal to the tibial plafond using 9 previously published radiological measurement techniques. Inter- and intraobserver reliability were assessed for each evaluation method. Results: The syndesmotic area calculation showed the highest interobserver reliability (0.96), the highest intraobserver reliability for observer 2 (0.97), and the second highest intraobserver reliability for observer 1 (0.92). Fibular rotation had the second highest interobserver reliability in our results (0.84), with intraobserver reliability of 0.91 and 0.8 for first and second observers, respectively. The intraobserver reliability of the side-by-side method was 0.49 and 0.24 for the first and second observers, respectively, and the interobserver reliability was 0.26. Conclusion: Qualitatively assessing syndesmotic reduction via side-by-side comparison with the uninjured ankle had the least intra- and interobserver reliability and should not be relied on to determine syndesmotic reduction quality. In contradistinction, syndesmotic area calculation demonstrated the highest reliability when evaluating syndesmotic reduction, followed by fibular rotation. Given that syndesmotic area measurement techniques are not readily available on standard image viewers, technologically updating image viewers to allow such calculation would make this approach more accessible in clinical practice. Level of Evidence: Level IV, case series.

Utility of Volumetric Measurement via Weight-Bearing Computed Tomography Scan to Diagnose Syndesmotic Instability

“…Recent studies have suggested that WBCT may play a more useful role in diagnosing patients with subtle syndesmotic instability by virtue of its ability to visualize the distal syndesmosis cross-sectionally and under physiologic load. 1,2,4,7,9,13,17 This study found that measuring the volume of the syndesmotic joint on WBCT and comparing this measurement with the contralateral uninjured side is an effective method to detect syndesmotic instability. Compared with the contralateral uninjured side, 3D WBCT volume measurements were increased at the injured side among patients diagnosed with arthroscopically confirmed syndesmotic instability.…”

“…Recent studies have suggested that WBCT may play a more useful role in diagnosing patients with subtle syndesmotic instability by virtue of its ability to visualize the distal syndesmosis cross-sectionally and under physiologic load. 1,2,4,7,9,13,17…”

“…10,12 Weight-bearing computed tomography (WBCT) allows cross-sectional visualization of the ankle while under physiologic load. 1,2,4,7,9,13,17 Furthermore, its ability to evaluate both the injured and uninjured sides is critical given the variable anatomy of the incisura across individuals. 4,7,9 Syndesmotic instability, however, represents a 3-dimensional (3D) problem that entails varying components of both translational and rotational disturbance of fibular position relative to the tibia.…”

Intraoperative three-dimensional imaging in ankle syndesmotic reduction

“…At least 3 different measurement methods are necessary to record the relevant criteria of translation medial / lateral, anterior / posterior and fibular rotation. In particular, the sole qualitative side-by-side comparison without measurement data collection shows a very low level of intra-and interobserver reliability and should not be used as an assessment parameter [33].…”

Intraoperative three-dimensional imaging in ankle syndesmotic reduction.

“…At least 3 different measurement methods are necessary to record the relevant criteria of translation medial / lateral, anterior / posterior and bular rotation. In particular, the sole qualitative side-by-side comparison without measurement data collection shows a very low level of intra-and interobserver reliability and should not be used as an assessment parameter [33].…”