Computed Tomography Analysis of Distal Tibia Physeal Fracture Patterns: A Classification and Technique for Optimizing Screw Trajectory

Abstract

Background: Fractures involving the anterolateral distal tibia, often referred to as Tillaux or Triplane fractures, are often treated operatively to achieve an anatomic reduction of the ankle joint articular surface. Although axial images from computed tomography scans are commonly obtained to measure displacement, no studies have examined these fracture patterns in the axial plane. This information may be useful to guide screw trajectory with only fluoroscopic imaging intraoperatively. Methods: We queried an institutional radiology report database for all “Tillaux” or “triplane” fractures and manually reviewed to identify fractures with an anterolateral tibia fragment. The axial image immediately caudal to the physis or physeal scar was used for measurements. The angle between the incisura and the fracture line exiting the incisura was measured. The width of the fracture fragment and the anterior distal tibia was then measured perpendicular to the incisura, representing the width that would be seen on an intraoperative mortise. A cluster analysis was performed to identify fracture patterns. Results: The average age of patients included in the study was 16 ± 2 years. Sixty-nine patients met inclusion criteria 32 patients with Tillaux fractures (46.4%) and 37 patients with triplane fractures (53.6%) met study inclusion criteria for a total of 69 patients. The cluster analysis demonstrated 3 fracture patterns. For type 1 (n=16), the mean was 24.5 ± 6.5 degrees from the incisura and the mean distance from the tibiofibular joint was 21.1 ± 6.3%. For type 2 (n=20), the mean was 58.6 ± 7.2 degrees and the mean distance was 48.7 ± 8.9%. For type 3 (n=33), the mean was 88.6 ± 6.3 degrees and the mean distance was 49.1 ± 9.7%. Conclusions: This is the first study to identify that pediatric distal tibia physeal fractures occur in 3 common patterns with consistent fragment sizes and fracture planes. This information can optimize screw start point and trajectory in the axial plane when referencing a mortise x-ray and C-arm beam. Level of Evidence: Diagnostic, Level III.