Calcaneus avulsion fracture oblique view

On this internal oblique plain radiograph of the ankle, a calcaneal avulsion fracture of the extensor digitorum brevis origin can be seen (arrow). The os tibiale externum, a normal accessory ossicle, can be seen at the opposite side of the foot in its typical location (arrowhead). Note the difference in appearance between the ragged margins of the fracture fragment and the smooth regular contours of the ossicle.