Impact of the Subtle Lisfranc Injury on Foot Structure and Function

Background: The subtle Lisfranc injury is the disruption of the osteoligamentary complex between the first cuneiform and the second metatarsal, resulting in minor widening of this space that is often difficult to detect with plain radiographs. In this study, we assessed the results after treatment of the different stages of subtle Lisfranc injuries, focusing on their impact on foot arch anatomy and functionality at short- to midterm follow-up. Methods: A retrospective study including patients treated in our center for a subtle Lisfranc injury between 2012 and 2019 was conducted. Demographic, epidemiologic, radiographic, and clinical data were obtained and assessed, focusing on foot arch structure and foot function, which was evaluated with the American Orthopaedic Foot & Ankle Society (AOFAS) midfoot score and the Foot Function Index (FFI). Results: A total of 42 patients with a mean age of 49 ± 17.5 years were included, with an average of 4.3 years’ follow-up (range, 1-8). Stage I injuries according to Nunley classification represented 19% and were treated conservatively. Stage II (66.7%) and stage III (14.3%) injuries were treated operatively, via osteosynthesis with screws (74%), K-wires (19%), or plates (7%). Flattening of foot arch after treatment was observed in 42.9% of patients, with significant increases in Costa-Bertani (12 ± 7 degrees), Hibbs (7 ± 6 degrees), and Meary (3 ± 1 degrees) angles. Other complications included complex regional pain syndrome (28.6%) and painful hardware (23.8%). Secondary joint arthrodesis was needed in 16.6% of patients. Chronic pain was present in 71.4% of patients with a mean visual analog scale (VAS) pain score at final follow-up of 4 of 10 points. Results in AOFAS midfoot score and FFI were 87.4 ± 8.3 and 15 ± 6.4, respectively. Conclusion: The subtle Lisfranc injury shows dissociation between the initial relatively mild radiographic changes and important future complications. Chronic pain and foot arch flattening were not uncommon. Overall foot function in the short- or midterm was found to be modestly diminished in this somewhat heterogenous cohort. Level of Evidence: Level IV, therapeutic case series.