Foot Pathology: Metatarsal Fractures

Metatarsal fractures are often readily detected on conventional radiographs of the foot, with the exception avulsion fractures of proximal tip of the tuberosity at the base of the 5th metatarsal, which can require an AP ankle radiograph. However, in the setting of a hyperflexion injury, a study by Preidler et al. demonstrated the benefit of CT over conventional radiographs. Forty-nine patients with hyperflexion injuries to the foot were evaluated with conventional radiographs (with and without weight bearing), CT and MR. There were 53 metatarsal fractures seen on CT and 41 tarsal fractures. MR detected only 41 of the metatarsal fractures and 39 of the tarsal fractures. The conventional radiographs revealed only 33 of the metatarsal fractures and less than half of the tarsal fractures. The most commonly fractured metatarsal bone in was the 2nd. In this type of trauma, the cuboid was the most frequently fractured tarsal bone. The authors advocate the use of the CT to properly evaluate the foot following a hyperflexion injury .

Lis Franc Fracture dislocations occur following severe abduction injury and ligamentous disruption to the foot. Causes of this mechanism of forced plantar flexion and fracture/dislocation include fall, motor vehicle or motorcycle accident. As a result, various combinations of lateral displacement of the lateral 4 metatarsals and medial or lateral displacement of the 1st metatarsal are seen in combination with fractures of the base of the 1st and/or second metatarsal. The cuboid may fracture as well. Once detected on conventional radiographs, this type of fracture/dislocation is best evaluated with CT, to determine which metatarsal bones are affected and detect associated fractures of the cuboid, cuneiform and navicular.