The tibiofibular clear space is a radiographic measure and defined as the space between the groove of the distal tibial prominence and the medial margin of the distal fibula 1-3.
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Usage
Together with the tibiofibular overlap and the medial clear space, the tibiofibular clear space has been used in the diagnosis of syndesmotic injury 1-3 and the assessment of its repair 2.
Measurement
The tibiofibular clear space can be measured on an AP or mortice view of the ankle 6. It is measured 1 cm above the tibial plafond. It is described as the horizontal distance between the deepest point of the fibular groove or posterior tibial tubercle and the medial edge of the distal fibula 1-3.
Interpretation
The mean is 4.6 mm (AP) and 4.3 mm (mortice) 6. In the context of an absence of any tibiofibular overlap (TFO <0) and a widened medial clear space, a horizontal distance of >6 mm has been considered abnormal 1.
Practical points
There is some debate on how useful this measurement with the above parameters for the prediction of a syndesmotic injury is 1,4. The correlation of the tibiofibular clear space and tibiofibular overlap with the finding of syndesmotic injury in MRI seems to be quite poor 1,5. Although it seems to have some value in the assessment of the reduction 2.