Triplane ankle fractures are complex transitional fractures that often necessitate surgical treatment. Axial fracture lines determine optimal screw trajectories for fixation. The purpose of our study was to identify fracture patterns in triplane fractures by illustrating fracture lines in the axial plane of the distal tibial metaphysis and epiphysis.
We retrospectively reviewed records of children presenting with ankle fractures at 1 center from January 2007 through June 2017. Thirty-three cases of triplane fractures with available computed tomographic (CT) scans were identified. Fractures in the axial plane of the metaphysis were identified 10 mm proximal to the physis, and fractures in the epiphysis were identified midway between the physis and distal tibial articular surface. Fracture lines were drawn and were superimposed on unfractured bone templates to generate fracture maps, and heat maps were then created to show areas of high and low fracture densities.
In the metaphysis, the most common fracture pattern was medial-lateral lines in the posterior metaphysis. This metaphyseal pattern was consistent across 2, 3, 4, and 5-part fractures. There were clear zones of rare fracture involvement in the anterior and anterolateral metaphysis. In the epiphysis, anterior-to-posterior fracture lines were common in the anterior epiphysis. All cases had an epiphyseal fracture exit through the anterior epiphysis. Fracture extension into the posteromedial epiphysis was a feature of all fracture classes.
Fracture mapping of triplane fractures suggests consistent axial fracture patterns in the metaphysis and epiphysis with additional class-dependent fractures in the epiphysis. This study provides visual guidelines to assist surgeons in understanding the axial fracture patterns of individual triplane fractures for surgical planning.