Blount disease

Alternate names

Tibia vara; Osteochondrosis deformans tibiae; Blount's disease; Blount-Barber syndrome; Erlacher-Blount syndrome; Osteochondrosis deformans tibiae, familial infantile type

Definition

Blount disease is a growth disorder of the shin bone (tibia) characterized by inward turning of the lower leg (bowing) that slowly worsens over time.

Types

• There are two types of Blount disease (early-onset and late-onset), based on whether symptoms begin before or after four years of age.
• Blount disease may occur in one or both legs and can lead to shortening of the affected leg and other changes within bones of the legs.

Epidemiology

Infantile Blount disease, also known as pathologic genu varum, is generally seen in children 2 to 5 years of age, with males more likely to develop than females and bilateral 50% of the time. Adolescent Blount disease, also known as adolescent genu varum, is more likely to be seen in children >10 years of age, generally less severe, more likely to be unilateral. Infantile Blount disease is more frequent than adolescent Blount disease and typical of the early walkers, Hispanics, and Afro-Americans.[1].

Cause

• The Cause of Blount disease is thought to be multifactorial.
• Mechanical overload and genetic susceptibility are considered as risk factors.
• Mechanical overload leads to osteochondrosis of the medial proximal tibial physis and epiphysis, later progresses to a physical bar.
• Overweight children, in particular in specific demographic populations such as Hispanics and Blacks, are reported as more likely to develop this condition.

Signs and symptoms

One or both of the lower legs turn inward. This is called "bowing." It may:

• Look the same on both legs
• Occur just below the knee
• Rapidly get worse

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Tibial bowing(Bowed shankbone)

30%-79% of people have these symptoms

• Abnormality of the knee
• Abnormality of the proximal tibial epiphysis(Abnormality of the end part of innermost shankbone)
• Abnormality of the tibial metaphysis
• Osteochondrosis

Diagnosis

The health care provider will examine you. This will show that the lower legs turn inward. An x-ray of the knee and the lower leg confirms the diagnosis.

Treatment

• Braces are used to treat children who develop severe bowing before the age of 3.
• Surgery is most often needed if braces do not work, or if the problem is not diagnosed until the child is older. Surgery may involve cutting the shin bone to place it in the proper position. Sometimes, the bone will be lengthened as well.
• Other times, surgery is done to restrict the growth of the outer half of the shin bone. This allows the child's natural growth to reverse the bowing process. This is a much smaller surgery. It works best in children with less severe symptoms who still have quite a bit of growing to do.

Prognosis

If the leg can be placed into the proper position, the outlook is good. The leg should work properly and look normal.

Possible Complications

• Failure to treat Blount disease may lead to progressive deformity. The condition may lead to differences in leg lengths, which can result in disability if not treated.
• Blount disease may come back after surgery, especially in younger children.

NIH genetic and rare disease info

• NIH info on Blount disease

Blount disease is a rare disease.

Blount disease Resources
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