Os trigonum

Case contributed by Dr Behrang Amini


The patient had presented with a sprained ankle, and a tibiotalar joint effusion is evident anteriorly.


Lateral view of the ankle demonstrates a well-corticated rectangular bone fragment posterior to the left talus. This is consistent with an os trigonum, a common accessory bone found just posterior to the lateral tubercle of the posterior talar process. In this case, the os trigonum, appears to be partially fused with the lateral tubercle.

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Case information

rID: 7941
Published: 24th Dec 2009
Last edited: 4th Oct 2015
Inclusion in quiz mode: Included

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