Pediatric Blount Disease: An Introduction

Blount disease is a developmental disorder of the proximal tibia that encompasses two types: early onset (includes infantile or juvenile) and late onset (adolescent). In the infantile group, the clinical manifestations first appear as soon as the child begins to ambulate. It usually presents as excessive genu varum (often bilateral) that may be difficult to distinguish from physiological genu varum. Because growth of the posteromedial proximal tibial physis is affected, Blount disease typically creates a multi-planar deformity. Proximal tibial varus, procurvatum (apex anterior), internal tibial torsion, and, in unilateral cases, limb length discrepancy can all occur simultaneously. Medial plateau depression occurs if the disease progresses (usually after the age of 6 years) and indicates the medial physis is nonfunctional or absent due to the development of a bony bridge medially. In the adolescent type, distal femoral valgus may coexist with the varus tibial deformity. The goal of treatment is to restore normal mechanical alignment to the limb in order to prevent the development of degenerative changes in the knee (Table 1).