• OBJECTIVE
    • The goal of the present study was to compare the diagnostic yield of weight-bearing radiographs with non-weight-bearing computed tomography (CT) scan for subtle Lisfranc (LF) injuries in the ED.
  • METHODS
    • Retrospective analysis of patients presenting with a suspected LF injury over a 2 year period from 2016 to 2017 who had both weight-bearing bilateral foot radiographs and CT scan. Information extracted included patient demographics, radiographic findings of metatarsal fractures, fleck sign and measurements of diastasis between the medial cuneiform and second metatarsal expressed as a ratio of the uninjured side, clinical findings and treatment modality. Radiologist reports were recorded as either positive, negative or equivocal for a LF injury.
  • RESULTS
    • A total of 117 patients were included with a mean age of 38 years and 54% (n = 63) women. When initial weight-bearing radiographs were positive, 54% of subsequent CT scans were reported as either equivocal or negative. Of the patients who had a negative or equivocal weight-bearing radiograph, only 12% had a positive CT scan. The mean diastasis ratio in patients undergoing surgery was 1.53 (95% confidence interval 1.41-1.65) compared to 1.11 (95% confidence interval 1.07-1.16) for patients with injuries not requiring operative intervention (P < 0.001). There was a statistically significant correlation between a positive weight-bearing radiograph and surgical treatment (R = 0.339, P < 0.001), and between diastasis measurements and surgical treatment (R = 0.576, P < 0.001).
  • CONCLUSIONS
    • CT provides limited benefit in the diagnosis and initial management of suspected subtle LF injuries in the ED. We advocate for the use of bilateral weight-bearing radiographs as a first-line investigation.