When children are nearing the end of their growth, the distal tibial physis does not close all at once. Rather, the central region of the physis begins to close first. The medial region closes next, and the lateral region is last. Because the open physis is weaker than the nearby bone, common patterns of “transitional” ankle fractures occur.
The triplane fracture is Salter-Harris Type IV injury involving the epiphysis, physis, and metaphysis. In this injury, there are, as the name implies, three distinct fracture lines: one through the epiphysis in the sagittal plane, another through the open physis in the axial plane, and a third through the metaphysis in the coronal plane.
The Tillaux fracture is a fracture of the anterolateral epiphysis, or a Salter-Harris Type III injury.
Triplane and Tillaux fractures are two of the most common transitional ankle injuries, but other variants can occur.
Full Article - https://www.orthopaedia.com/pediatric-fractures-of-the-lower-extremities/#Transitional-Ankle
