Radiography versus computed tomography for displacement assessment in triplane fractures: A pilot study

Introduction: Triplane fractures occur primarily in adolescent patients aged 12-15 years who are approaching skeletal maturity, and account for 5% to 10% of ankle fractures. The purpose of this paper is to determine whether radiographs or computed tomography provide superior assessment of the displacement of triplane fractures. Methods: A retrospective chart review was conducted. Patient demographics, fracture classification, imaging modalities, management, and outcomes were recorded. Plain radiographs and computed tomography scans obtained at the time of injury were measured. Outcomes were scored with the modified Weber ankle protocol. Statistics were performed using a T test of dependent samples. Results: Ten patients with triplane fractures were identified. The average age was 12.3 (11-13) years at the time of injury and 8 (80%) patients were female. Average displacement measured on X ray was 1.9 (1.0-3.2) mm. Average displacement on CT was 4.1 (2.0-6.0) mm. CT scans were found to measure greater displacement compared to radiographs (p=0.002). The average intra-articular gap measured via CT was 2.7 (1.5-3.8) mm and average articular step-off was 0 mm. According to the modified Weber protocol, all patients had excellent outcomes with scores of 5 points or less. Conclusion: Our results support CT as a modality that provides more information about the displacement of triplanar pediatric ankle fractures than plain radiographs, which can be helpful with medical decision making. CT provides more accurate measurement about articular fracture displacement but did not demonstrate more fragments. In this cohort, fracture gap, not step off, was the common issue.