We tried toevaluate the role of lateral malleolus in development and biomechanics of ankle in growing children through the clinical long-term follow-up study for the nine cases of fibular pseudoarthrosis and also the nine children with epiphyseal
injury
of distal tibial epiphysis, and followed them for more than 10 years.
As a first part of this study, nine children had valgus deformity of the ankle, resulting from fibular pseudoarthrosis due to post-traumatic or sequelse of fibular osteomyelitis and treated by Langenskiold's bone grafting in four, supramalleolar
corrective osteotomy in 3 and observation in 2 children. The Langenskiold operation to make a bony bridge between tibial and fibular metaphyses on just below the pseudoarthrosis was effective to prevent the valgus ankle deformity in growing
child,
but
the ankle deformity was recurred again in long-term follow-up and needed to corrective osteotomy later. The mechanism of production of the lateralmalleolar elevation and of the valgus ankle deformity was removal of the physiologic thrust of
growth
contribution by the proximal fibular epiphysis, tethering effect of inelastic soft tissue around the pseudoarthrosis and also the early closure of lateral part of distal tibial epiphysis due to longstanding concentration of stress by increasing
valgus
ankle. As a sccond part of study, nine children had varus and internal rotational deformities of the ankle, resulting from fracture or fracture-separation of distal tibial epiphysis but intach the fibular and its epiphysis, and treated initially
by
percutaneous K-wire fixation. The distal fibula was hypertrophied, their cortex was also thickened and lateral bending deformity was severe upto 80。as adaptive changes according to the severity of varus deformity. The mechanism of varus ankle
deformity
was the pulling down action of tibio-fibular ligament and joint capsule by the continuous fibular growth to the distal tibia which was arrested in growth by on distal tibial epiphysis the trauma.
As a conclusion, the fibula in growing children was very important to develop the normal ankle and in its biomechanics, and if it is damaged in grwing period, it must be restored to normal ankle and also followed them for the end of skeletal
maturity.
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