Re: Liz Frank Fracture : Need to operate?

Fractures and Dislocations

The six-bone tarsometatarsal complex is known as the Lisfranc joint. Injuries to this joint are not uncommon, and unfortunately up to 20 percent of these injuries are missed in the emergency department.5 The plantar ecchymosis sign, a bruise on the plantar surface of the midfoot, is suggested as an occult sign of an injury.6 The force required and the mechanism of injury are varied and can range from a seemingly minor rotational force to a severe axial load, as seen in an automobile accident. The great majority of injuries to the Lisfranc joint are associated with fractures, usually of the metatarsals, the cuboid, or the cuneiforms. A fracture of the base of the second metatarsal is pathognomonic of a disruption of the Lisfranc ligamentous complex (Figure 277-3). The Lisfranc injury is classified by the direction of the dislocation. A divergent dislocation describes metatarsals splayed in medial and lateral directions, usually between the first and second metatarsals. In isolated dislocations, one or more metatarsals are displaced from the rest. In homolateral dislocations, all five metatarsals are displaced in the same direction, either laterally or medially. Suspect this injury if there is point tenderness over the midfoot or when there is laxity between the first and second metatarsals in a dorsal-to-plantar direction. Diagnosis is made radiographically on the anteroposterior view when there is a gap larger than 1 mm between the bases of the first and second metatarsals. Other radiographic signs are loss of alignment of the medial edge of the base of the second metatarsal with the medial edge of the middle cuneiform on the anteroposterior or oblique view; loss of alignment of the lateral border of the third metacarpal shaft with the lateral border of the lateral cunei-form on the oblique view; or loss of alignment of the medial border of the fourth metatarsal with the medial border of the cuboid on the oblique view (Figure 277-4).5 Weight-bearing radiographs have been suggested to make the diagnosis, but recent studies have suggested that CT scanning is the imaging modality of choice.7 Injuries to the Lisfranc joint frequently require open reduction and fixation or percutaneous placement of Kirschner wires and non-weightbearing for several weeks. These injuries are complicated by dorsalis pedis artery damage in the short term and degenerative arthritis and chronic pain in the long term.