400
The arrow in this xray denotes the "fleck sign", a bony fragment between the first and second metatarsals, suspicious for a fracture at the base of the second metatarsal. This is often seen in what unique foot fracture?
What is a Lisfranc fracture.
The Lisfranc fracture occurs secondary to axial loading with forced plantar flexion (such as with bicycle or horseback riders whose foot gets caught in the pedal or stirrup) or with crush injury during motor vehicle accidents. This mechanism results in injury to the tarsometatarsal joint complex. AP radiograph of the foot shows widening of the space between the first and second metatarsals and cuneiforms (asterisk) - although this is often not recognized if the film is non-weight bearing, so high clinical suspicion must be maintained.