fractures of the tibial plateau are caused by a varus (inwardly angulating) or valgus (outwardly angulating) force combined with axial loading or weight bearing on knee. the classically described situation in which this occurs is from a car striking a pedestrian's fixed knee ("bumper fracture"). however most of these fractures occur from motor vehicle accidents or falls. injury can be due to a fall from height in which knee forced into valgus or varus. the tibial condyle is crushed or split by the opposing femoral condyle, which remains intact.