The outcomes of 18 ipsilateral displaced femoral and tibial fractures in 17 children are assessed and a new classification system is proposed. Average age was 8.75 years, and follow-up averaged 3.2 years. In the modified Bohn and Durbin classification used, eight cases were type I, four were type II, three were type IIIa, one was type IIIb, and two were type IV. In tibial fractures there was angulation in three cases, and in femoral fractures there were dislocation and angulation in four cases, refracture in one case, leg length discrepancy in four cases, and asymptomatic knee ligament injury and meniscal tearing in five cases. According to Yue et al's criteria, seven outcomes were excellent, eight were good, two were fair, and two were poor. The cases with poor outcomes were those with open knee injury, and those with fair outcomes were those with angulation. It was concluded that knee ligament injuries do not affect the outcome of floating knee trauma in children, although they do in adults, but that open knee injuries do affect the outcome, and operative treatment of the femoral fracture is the treatment of choice for all ages.