Chip fracture from talus. Note the small triangular fleck of bone lifted from the superior surface of the neck of the talus just proximal to the talo-navicular joint. This is commonly seen as a small fragment of bone with cortex all around or as a small projecting exostosis. In either case, it probably represents the appearance of an old fracture in this region.
The present film represents the appearance of the recent fracture which is not very often seen. It is probably due to pull of ligaments around the talo-navicular joint.