Lisfranc injury: Refined diagnostic methodology using weightbearing and non-weightbearing radiographs

Background: To compare diagnostic parameters for Lisfranc instability on WB and NWB radiographs and to assess the inter-observer reliability of a standardized diagnostic protocol. Patients and methods: Patients who had undergone surgical treatment for subtle, purely ligamentous Lisfranc injury with both WB and NWB post-injury, pre-surgery films (n = 26) were included in this multicentre, retrospective comparative study. Also included was a control group (n = 26) of patients with isolated fifth metatarsal avulsion fractures who similarly had both WB and NWB films. Multiple midfoot distance and alignment measurements were used to evaluate the Lisfranc joint on both WB and NWB views. To evaluate interobserver reliability, measurements were made by two independent observers across a cohort subset. Results: When comparing the NWB views between groups, only C1M2 (medial cuneiform- second metatarsal) distance was found to be significantly larger (∆ = 1.35 mm, p 0. 90 were found when interpreting WB radiographs and ICC's ranging between 0.61 and 0.80 were found when interpreting NWB radiographs. Conclusion: Using WB imaging for diagnosing subtle Lisfranc instability reveals larger diastasis in the tarsometatarsal joint and has a higher interobserver reliability compared to NWB imaging. Clinical concern for subtle or occult Lisfranc instability in any patient should therefore trigger WB radiographic assessment since such injuries may be missed on NWB views.