Lisfranc injuries: Incidence, mechanisms of injury and predictors of instability.

BACKGROUND:In Lisfranc injuries the stability of the tarsometatarsal joints guides the treatment of the injury. Determining the stability, especially in the subtle Lisfranc injuries, can be challenging. The purpose of this study was to identify incidence, mechanisms of injury and predictors for instability in Lisfranc injuries. METHODS:Eighty-four Lisfranc injuries presenting at Oslo University Hospital between September 2014 and August 2015 were included. The diagnosis was based on radiologically verified injuries to the tarsometatarsal joints. Associations between radiographic findings and stability were examined. RESULTS:The incidence of Lisfranc injuries was 14/100,000 person-years, and only 31% were high-energy injuries. The incidence of unstable injuries was 6/100,000 person-years, and these were more common in women than men (P = 0.016). Intraarticular fractures in the two lateral tarsometatarsal joints increased the risk of instability (P = 0.007). The height of the second tarsometatarsal joint was less in the unstable injuries than in the stable injuries (P = 0.036). CONCLUSION:The incidence of Lisfranc injuries in the present study is higher than previously published. The most common mechanism of injury is low-energy trauma. Intraarticular fractures in the two lateral tarsometatarsal joints, female gender and shorter second tarsometatarsal joint height increase the risk of an unstable injury. LEVEL OF EVIDENCE:Level III, cross-sectional study.