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.