Tripod fracture

Tripod fracture. This cyclist was involved in an RTA and landed on the left side of his face. This oblique facial bone radiograph shows fractures of the inferior orbital rim and of the zygomatic arch (arrows). These are two of the components of a tripod fracture, the third being a fracture of the lateral wall of the orbit (which can be difficult to identify on radiographs, but was visible on this patient’s subsequent CT). Note the opacification of the left maxillary sinus (red asterisk) compared to the aerated sinus on the right (white asterisk). This is due to haemorrhage into the sinus, and can be a helpful indicator of significant occult traumatic pathology when plain films are normal. We have a low threshold for suggesting CT in the setting of facial trauma, as these fractures are frequently occult on radiographs.