Blount's disease

Definition

Blount's disease is a growth disorder of the shin bone (tibia) in which the lower leg turns inward, resembling a bowleg.

Alternative Names

Tibia vara

Causes, incidence, and risk factors

Blount's disease occurs in young children and adolescents. The cause is unknown but is thought to be due to the effects of weight on the growth plate. The inner part of the shin bone, just below the knee, fails to develop normally.

Unlike bowlegs, which tend to straighten as the child develops, Blount's disease slowly gets worse. It can cause severe bowing of one or both legs.

This condition is more common among African-American children. It is also associated with obesity and early walking.

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

Signs and tests

The doctor will perform a physical exam. This will show that the lower legs turn inward. An x-ray of the knee and the lower leg confirms the diagnosis.

See also: Joints x-ray

Treatment

Braces are used to treat children who develop severe bowing before the age of 3. If braces do not work, or if the problem is not diagnosed until the child is older, surgery is usually required. Surgery may involve cutting the shin bone to place it in the proper position, and sometimes lengthen it as well.

Other times, the growth of the outer half of the shin bone can be restricted. This is done with surgery, and allow the child’s natural growth to reverse the bowing process. This second, much smaller surgery is most effective in children with less severe symptoms who still have quite a bit of growing to do.

Expectations (prognosis)

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

Complications

Failure to treat Blount's disease may lead to progressive deformity. The condition may lead to differences in leg lengths, which can result in disability if not treated.

Blount's disease may come back after surgery, especially in younger children.

Calling your health care provider

Call for an appointment with your child's health care provider if your child's leg or legs appear to be bowing. Also call for an appointment if your child has bowed legs that appear to be getting worse.

Prevention

Weight loss for overweight children may be helpful.

References

Canale ST. Osteochondrosis or epiphysitis and other miscellaneous affections. In: Canale ST, Beatty JH, eds. Campbell's Operative Orthopaedics. 11th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap 29.