Lisfranc Sprain with Second Metatarsal Base Adaptive Stress Response in High-Level Athletes: Case Series and Novel Perspective on a Distinct Entity of Chronic Low-Energy Lisfranc Injury

Figure 1

(a) Sagittal proton-density-weighted, fat-suppressed sequence (PDFS) at the level of the second metatarsal. There is localized marrow oedema signal centered at the base of the second metatarsal plantar margin (circled), with adjacent soft tissue oedema. The inferior cortex is thickened, with presence of intracortical high signal consistent with osteitis (arrow). Periosteal oedema present. The intracortical signal traversing the base of the second metatarsal is suspicious for an undisplaced fracture. Axial sequences at the level of the second metatarsal base in proton density (PD) (b) and PDFS (c) show thickening of the plantar Lisfranc ligament (arrow) which returns intermediate signal but is otherwise intact, consistent with grade II sprain or partial tear. Undisplaced fracture at the metatarsal base as shown (dashed arrow). Sagittal (d) and axial (e) CT at the similar level demonstrates the avulsion fracture at the base of the second metatarsal at the site of the plantar Lisfranc ligament insertion (arrow). There is also cortical thickening of the border of the third metatarsal base at the site of plantar Lisfranc attachment (dashed arrow).

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