Additional Fracture Detection by Computed Tomography After Plain Radiography in Adults with Isolated Foot and Ankle Trauma: A Retrospective Selected-Cohort Study

Background/Objectives: Plain radiography is the first-line imaging modality for acute foot and ankle trauma; however, computed tomography (CT) may provide additional information in selected patients with persistent clinical suspicion, equivocal radiographic findings, or a need for detailed fracture characterization. We hypothesized that the CT-confirmed fracture proportion would be higher among patients with suspicious radiographs than among those with normal radiographs and that CT would identify additional fractures in a clinically selected cohort. Methods: This retrospective single-center selected-cohort study included 1000 adult patients with isolated foot and/or ankle trauma who underwent both plain radiography and CT during the same clinical encounter. Plain radiographs were categorized as normal, suspicious for fracture, or definite fracture on the basis of original radiology reports and available imaging records. A CT-confirmed fracture was defined as the presence of an acute fracture on CT. Analyses focused primarily on CT-confirmed fracture proportions and conditional diagnostic yield within the selected CT cohort. Conditional apparent diagnostic performance was evaluated as a supplementary sensitivity analysis and was not intended to estimate population-level diagnostic accuracy. Results: Plain radiographs were categorized as normal in 628 patients, suspicious in 283, and definite fracture in 89. CT detected acute fractures in 386 patients (38.6%). The CT-confirmed fracture proportions were 14.8% in the normal radiograph group, 72.1% in the suspicious radiograph group, and 100.0% in the definite fracture group. The proportion of patients without a definite fracture on plain radiography but with an acute fracture on CT was 29.7%. Fracture-pattern classification was unavailable in 85 of 386 cases with CT-confirmed fractures (22.0%); therefore, fracture-pattern analyses were considered exploratory. Conclusions: In this selected CT cohort, CT identified additional acute fractures in a subset of adult isolated foot and ankle trauma cases that could not be definitively classified as fractures on plain radiography. Because CT was not systematically performed in all trauma patients, the findings represent selected-cohort CT yield rather than true population-level diagnostic accuracy.