Application of external torque enhances the detection of subtle syndesmotic ankle instability in a weight‐bearing CT

Abstract

Purpose Acute syndesmotic ankle injuries continue to impose a diagnostic dilemma and it remains unclear whether weightbearing and/or external rotation should be added during the imaging process. Therefore, the aim of this study was to assess if combined weightbearing and external rotation increases the diagnostic sensitivity of syndesmotic ankle instability using weightbearing CT (WBCT) imaging, compared to isolated weightbearing. Methods In this retrospective study, patients with an acute syndesmotic ankle injury were analysed using a WBCT (N = 21; Age = 31.6 ± 14.1 years old). Inclusion criteria were an MRI conirmed syndesmotic ligament injury imaged by a WBCT of the ankle during weightbearing and combined weightbearing-external rotation. Exclusion criteria consisted of fracture associated syndesmotic injuries. Three-dimensional (3D) models were generated from the CT slices. Tibioibular displacement and talar rotation were quantiied using automated 3D measurements (anterior tibioibular distance (ATFD), Alpha angle, posterior Tibioibular distance (PTFD) and Talar rotation (TR) angle in comparison to the contralateral non-injured ankle. ResultsThe diference in neutral-stressed Alpha angle and ATFD showed a signiicant diference between patients with a syndesmotic ankle lesion and contralateral control (P = 0.046 and P = 0.039, respectively). The diference in neutral-stressed PTFD and TR angle did not show a signiicant diference between patients with a syndesmotic ankle lesion and healthy ankles (n.s.). Conclusion Application of combined weightbearing-external rotation reveals an increased ATFD in patients with syndesmotic ligament injuries. This study provides the irst insights based on 3D measurements to support the potential relevance of applying external rotation during WBCT imaging. In clinical practice, this could enhance the current diagnostic accuracy of subtle syndesmotic instability in a non-invasive manner. However, to what extent certain displacement patterns require operative treatment strategies has yet to be determined in future studies. Level of evidence Level III.

The Influence of Talar Displacement on Articular Contact Mechanics: A 3D Finite Element Analysis Study Using Weightbearing Computed Tomography

“…WBCT images were segmented into 3D models of bone using a DICOM-specific 3D rendering software (DISIOR Bonelogic Ortho Foot and Ankle Software, version 2.0, Paragon 28, Denver, CO). 22 For the WBCT arthrogram (n = 1), cartilage layers were manually segmented using an auto-segmentation software (Mimics version 21.0; Materialise, Leuven, Belgium). For the nonarthrogram WBCTs (n = 18), "personalized" cartilage layers were modeled based on a previously validated methodology.…”

Ins and Outs of the Ankle Syndesmosis from a 2D to 3D CT Perspective

“…Additionally, they found a significant difference in the average external rotation between the sprained group (mean = 4.7 • ) and the fracture group (mean = 7.0 • ) when compared to the control group (p < 0.05). Peiffer et al refined the examination of subtle syndesmotic lesions using external torque during WBCT [41]. Significance was proven for ATFW and alpha angle computed on patient-specific 3D models.…”