Blount Disease

Excerpt

Blount disease, also known as tibia vara, is an acquired genu varus deformity in children caused by disrupted normal cartilage growth at the proximal medial metaphysis of the tibia. This condition develops due to excessive compressive forces on the medial aspect of the proximal tibial physis, leading to altered enchondral bone formation. Blount disease can be either unilateral or bilateral and manifests in 2 forms—infantile and adolescent—distinguished by variations in age of onset and presentation. The infantile or early-onset form is commonly bilateral, typically manifests in children between the ages of 1 and 5, and tends to exacerbate after the initiation of walking. The adolescent form manifests at a later stage and may present as either unilateral or bilateral.

Although obesity, early walking, and African-American heritage are recognized as risk factors for developing Blount disease, the precise pathophysiology of the condition remains unclear. The severity varies from articular cartilage irregularities to limb length discrepancies. The treatment of Blount disease varies from bracing to surgical interventions and depends on the age and severity at presentation. Treatment options include knee-ankle-foot orthoses (KAFOs), corrective proximal tibial osteotomies with either acute or gradual fixation, and hemiepiphysiodesis.

Radiographic findings are diagnostic, and the Langenskiöld classification system (see Image. Langenskiöld Classification System) describes the 6 radiographic stages of Blount disease. Blount disease was first described by Walter Putnam Blount, a pediatric orthopedic surgeon, in 1937.