Medial clear space (ankle)

Last revised by Mohammad Osama Hussein Yonso on 16 Sep 2023

The medial clear space is a radiographic measurement that may be useful in the diagnosis of ankle instability, syndesmotic injuries and ankle fractures 5.

The medial clear space is used in the prediction of deltoid ligament injury 1 and in conjunction with the tibiofibular clear space the tibiofibular overlap and the superior clear space in the diagnosis of syndesmotic injury 2,3.

The medial clear space can be measured on the non-stressed and stressed ankle mortise views 2,5, as the widest distance between the lateral border of the medial malleolus and the medial side of the talus and is usually measured parallel to the superior talar articular surface 1-3. This can be measured at the level of the talar dome (common) or 5 mm inferior to the talar dome 2,5.

The medial clear space a horizontal distance of ≥4-5 mm has been considered abnormal 1-4 although there is criticism that the measurement is inaccurate and imprecise 2,6. There is apparently a difference between male and female and regarding height, which should be taken into account when indicating a diagnosis 4.

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