Changes in tibiofibular relationships due to growth disturbances after ankle fractures in children.

We analyzed the longitudinal growth of the distal tibial and fibular physes and the longitudinal displacement of the distal metaphysis and epiphysis of the fibula relative to the distal metaphysis and epiphysis of the tibia during growth using a roentgenstereophotogrammetric technique in eight children: six with a traumatic growth disturbance in one or both of the distal tibial and distal fibular physes and two with a normal ankle. In the normal ankles the distal fibular metaphysis moved distally in relation to the distal tibial metaphysis and the growth in the distal fibular physis was slower than that in the distal tibial physis. Growth arrest in the distal fibular physis and continued growth in the distal tibial physis resulted in distal displacement of the fibular metaphysis relative to the tibial metaphysis, probably due to traction on the distal ligaments of the fibula or more rapid growth in the proximal fibular physis than in the proximal tibial physis, or both. Valgus deformity of the ankle developed when the growth of the distal tibial physis exceeded the distal sliding of the fibula, as shown by the stereophotogrammetric analyses and orthoroentgenograms. Growth arrest in the distal tibial physis and continued growth in the distal fibular physis resulted in proximal sliding of the fibula, as shown by the roentgenstereophotogrammetric analyses and serial orthoroentgenograms. This mechanism compensated to some extent for the overgrowth of the fibula. Simultaneous growth arrest in both the distal tibial and the distal fibular physis was associated with movement of the distal end of the fibula in a distal direction relative to the tibia, probably due to the more rapid growth in the proximal fibular physis than in the proximal tibial growth plate. Therefore, growth arrest of the distal tibial or fibular physis may result in either proximal or distal sliding of the fibular metaphysis in relation to the tibial metaphysis. Probably growth arrest in the distal fibular physis has a less favorable prognosis than arrest in the distal tibial physis, because after tibial arrest proximal sliding of the fibula may compensate for overgrowth of the fibula better than distal sliding of the fibula can compensate for fibular arrest and overgrowth of the tibia.