Triplane fracture of the distal tibia. A variant in cases with an open growth plate.

We have reviewed 15 cases of triplane fracture of the distal tibia. The mechanism of injury is lateral rotation and the anatomical pattern of the fracture depends on the state of the growth plate at the time of injury. In seven of our cases the anteromedial part of the growth plate was fused, but in eight children the plate was completely open. In six of these eight children there was a hump or projection of the medial growth plate. It is suggested that this hump stabilises the anteromedial part of the epiphysis in a manner similar to the partial anteromedial fusion seen in older children, and that this accounts for the occurrence of triplane fracture in the presence of an open growth plate.