RESUMO
The authors present 16 cases of post-traumatic genu valgum in children and discuss the pathogenesis of the deformity. In addition to mechanical factors (imperfect reduction of the fracture, inadequate immobilization, "bow string" effect of the intact fibula and the antero-lateral muscles of the thigh, altered load-bearing axis) there are biological factors of much greater importance. These are damage to the lateral aspect of the proximal growth cartilage of the tibia, with augmented growth on the medial side due to stimulation at the fracture site and periosteal detachment. All our cases were treated by osteotomy and there were 7 partial relapses, the causes of which are discussed. Osteotomy is tantamount to a second fracture, so must have regard to the pathological factors related to relapse. The authors recommend that corrective osteotomy of the tibia should always be associated with osteotomy of the fibula to avoid the "bow string" " effect. They also advise over correction of the deformity by about 5 degrees and immobilization in a full spica plaster to ensure maintenance of correction and rapid healing. For the same reason, perfect contact between the osteotomised surfaces is essential.
