Tibia Vara (Blount Disease)

Tibia Vara (Blount Disease)

Tibia vara is the most common pathologic disorder associated with genu varum. It is characterized by abnormal growth of the medial aspect of the proximal tibial epiphysis, resulting in a progressive varus deformity. Blount disease is classified according to age of onset:
• Infantile (1-3 years)
• Juvenile (4-10 years)
• Adolescent (>11 years)
Late onset Blount disease is less common than infantile disease. The cause is unknown, but it is felt to be secondary to growth suppression from increased compressive forces across the medial knee.

Clinical Manifestations

Infantile tibia vara is more common in African Americans, females, and obese patients. Many patients were early walkers. Nearly 80% of patients with infantile Blount disease have bilateral involvement. It is usually painless. The patients will often have significant internal tibial torsion and lower extremity leg-length discrepancy. There may also be a palpable medial tibial metaphyseal beak.
Late onset Blount disease is more common in African Americans, males, and patients with marked obesity. Only 50% have bilateral involvement. The initial presentation is usually painful bowlegs. Late onset Blount disease is usually not associated with palpable metaphyseal beaking, significant internal tibial torsion, or significant leg length discrepancy.

Radiologic Evaluation

Weight-bearing anteroposterior and lateral radiographs of both legs are necessary for the diagnosis of tibia vara. Fragmentation, wedging, and beak deformities of the proximal medial tibia are the major radiologic features of infantile Blount disease. In late onset Blount disease, the medial deformity may not be as readily noticeable. It can be very difficult to tell the difference between physiologic genu varum and infantile Blount disease on radiographs in the patient younger than 2 years of age.

Treatment

Once the diagnosis of Blount disease is confirmed, treatment should begin immediately. The use of orthotics to unload the medial compressive forces can be done in children younger than 3 years of age with a mild deformity. Compliance with this regimen can be difficult. Nonoperative management of more severe Blount disease is contraindicated.
Any patient older than 4 years should undergo surgical intervention. Patients with moderate to severe deformity and patients that fail orthotic treatment also require surgical intervention. Proximal tibial valgus osteotomy with fibular diaphyseal osteotomy is the usual procedure performed.