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ACEP Now: Vol 36 – No 12 – December 2017French surgeon Jacques Lisfranc de St. Martin, for whom the Lisfranc joint and Lisfranc fracture are named.
Painting by an unspecified artist; photo by Pierre Petit, Public Domain
A 24-year-old male presents to the emergency department after sustaining an injury to his right foot during football practice the previous day. He states he was viciously tackled while sprinting across the field. After falling on a plantar-flexed, fixed foot, he felt a snap in the center of his foot and developed immediate pain and swelling over the dorsum of his foot. On physical exam, there is maximal swelling over the first and second tarsometatarsal joints, and he is unable to bear weight.
Introduction
The midfoot is composed of the cuboid, navicular, and three cuneiform bones, which form the arch of the foot. The Lisfranc joint complex is composed of the bones and ligaments that connect the midfoot to the five metatarsals of the forefoot.1 The Lisfranc ligament connects the base of the second metatarsal to the lateral aspect of the medial cuneiform (see Figures 1 and 2).1,2 This oblique ligament is what provides stability to the joint, despite the absence of a ligamentous connection between the first and second metatarsal.
The annual incidence of Lisfranc injuries is 1 in 55,000 persons per year.3 These injuries can be difficult to recognize and are most commonly misdiagnosed as an ankle sprain on initial visit to the emergency department. Undiagnosed cases can result in long-term misalignment and functional weight-bearing difficulties. Therefore, it is important to keep a high index of suspicion and perform a detailed physical exam. Also, keep in mind that 20 percent of Lisfranc joint injuries are missed on initial radiograph.3
What Is the Mechanism of Injury?
These injuries can result from a direct crush mechanism or high-velocity blunt trauma, such as from a motor vehicle accident. However, the injury most commonly occurs indirectly from extreme plantar flexion with rotation of the ankle, during which the second metatarsal is prone to dislocate dorsally if an axial load is applied at the same time.3 Examples include falling from a horse with the foot caught in the stirrup, stepping off a curb, or planting your foot in a hole.
Figure 1: Normal AP weight-bearing radiograph of the left midfoot showing first metatarsal base (M1), second metatarsal (M2), third metatarsal (M3), medial cuneiform (C1), middle cuneiform (C2), lateral cuneiform (C3), and navicular bone (Nav). Note that there is less than 2 mm between C1 and M2 and between M1 and M2.
Credit: Siddiqui N A, Galizia M S, Almusa E, et al. RadioGraphics. 2014;34(2):514-531.
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