This retrospective comparative study tested whether 3D volumetric WBCT measurement of the distal syndesmosis outperforms standard 2D WBCT measurements for diagnosing syndesmotic instability. 12 patients with arthroscopically confirmed instability were compared to 24 controls using bilateral WBCT, with the contralateral ankle as an internal reference.
Syndesmotic instability is a 3D problem — the fibula translates and rotates in multiple planes relative to the tibia. But traditional imaging has evaluated it in 2D. Weight-bearing radiographs lack sensitivity, external rotation stress views load the deltoid more than the syndesmosis, and MRI shows ligament injury but not instability in the unloaded state.
When your WBCT 2D measurements are equivocal and you still suspect instability, request volumetric analysis from the tibial plafond to 5 cm proximally on bilateral WBCT. A ratio of the injured-to-uninjured volume approaching 1.8 is the target signal. If the contralateral ankle is uninjured and bilateral imaging is available, this measurement is reproducible (ICC 0.92–0.94) and more sensitive than any single 2D metric.
The key limitation to know for practice: this technique requires a healthy contralateral ankle and is not yet embedded in standard WBCT viewing software. Manual post-processing is currently needed, which limits routine clinical adoption.
This retrospective comparative study tested whether 3D volumetric WBCT measurement of the distal syndesmosis outperforms standard 2D WBCT measurements for diagnosing syndesmotic instability. 12 patients with arthroscopically confirmed instability were compared to 24 controls using bilateral WBCT, with the contralateral ankle as an internal reference.
Syndesmotic instability is a 3D problem — the fibula translates and rotates in multiple planes relative to the tibia. But traditional imaging has evaluated it in 2D. Weight-bearing radiographs lack sensitivity, external rotation stress views load the deltoid more than the syndesmosis, and MRI shows ligament injury but not instability in the unloaded state.
When your WBCT 2D measurements are equivocal and you still suspect instability, request volumetric analysis from the tibial plafond to 5 cm proximally on bilateral WBCT. A ratio of the injured-to-uninjured volume approaching 1.8 is the target signal. If the contralateral ankle is uninjured and bilateral imaging is available, this measurement is reproducible (ICC 0.92–0.94) and more sensitive than any single 2D metric.
The key limitation to know for practice: this technique requires a healthy contralateral ankle and is not yet embedded in standard WBCT viewing software. Manual post-processing is currently needed, which limits routine clinical adoption.