The missed chapter on midfoot: Chopart injuries.

Purpose: Midtarsal injuries are often missed at initial presentation which may lead to long-term complications. Nonetheless, radiographs (XR) are used as a primary imaging method. The place of cone beam computer tomography (CBCT) remains unclear in the management of midfoot injuries. The aim of this study was to update imaging findings on traumatic ankle and foot injuries (TAAFI) with CBCT and to assess the sensitivity, specificity and accuracy of XR compared to CBCT for midfoot injuries detections.

Material and methods: All CBCT studies performed due to (TAAFI) that had previous XR were collected for a period of 5 years. They were retrospectively anonymized and analyzed by a radiologist. A second blinded study of XR was made by a second radiologist as a control.

Results: A total of 754 cases were included. Lisfranc and Chopart injuries were detected in 153 (20.2%) and 154 (20.4%) patients, respectively. Lisfranc and Chopart's lesions combined together were seen in 33 cases (10.7%). A blinded retrospective analysis of XR compared to CBCT shows a sensitivity of 64.9% (56.8-72.4%; 95% CI), a specificity of 95.0% (92.9-96.6%; 95% CI) and an accuracy of 88.9% (86.4-91.0%; 95% CI) for Chopart's injuries. Regarding Lisfranc, the sensitivity was 62.1% (53.9-69.8%; 95% CI), specificity 99.0% (97.8-99.6%; 95% CI) and accuracy 91.5% (89.3-93.4%; 95% CI).

Conclusion: This cohort study highlights the missed injuries of Chopart on XR and the low association with Lisfranc avulsions. The use of CBCT helps in detecting and assessing midfoot injury.