Adolescent tibia vara.

Abstract

Adolescent tibia vara is less common and less well described when compared to infantile tibia vara. Yet, the two share a significant number of features related to their epidemiology and histology. The two diseases differ most in their radiographic appearance. It does not, however, necessarily follow that their etiologies cannot be similar. By its epidemiology and histology, adolescent tibia vara appears to be related to repetitive trauma in the form of abnormal force directed on the medial tibial growth plate due to obesity, the adolescent growth spurt, or residual, incompletely corrected physiologic varus. Such forces may give growth plate suppression by the Heuter Volkman principle similar to what is thought to occur in infantile tibia vara. In the infant, this results in typical radiologic findings related to an epiphyseal ossification center which is cartilagenous and moldable and results in progressive medial wedging. In the adolescent, however, this ossification center is bony and, therefore, will not deform under stress. The growth plate, however, still responds with decreased growth resulting in varus deformity. Thus, adolescent tibia vara, by definition not related to trauma or infection, may in fact reflect the same pathologic process at work as in infantile tibia vara.