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

Unlike bowlegs, which tend to correct as the child develops, Blount's disease is progressive and the condition worsens. It can cause severe bowing of the legs and can affect one or both legs.

The condition is more common among African-American children. It is also associated with obesity and early walking. There does not appear to be an obvious genetic factor.

• Sudden bowing of one or both legs
• May be rapidly progressive
• May appear asymmetric
• Primarily occurs just below the knee

Physical examination shows that the lower legs angle inward. An X-ray of the knee and the lower leg confirms the diagnosis (see joints X-ray).

Mild deformity can be treated with a brace. Moderate to severe angulation may require surgery. Surgical treatment involves cutting the bone to straighten it and placing steel pins.

Return to normal function and cosmetic appearance is expected after treatment.

Failure to treat Blount's disease may lead to progressive deformity.

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.

Weight loss for overweight children may be helpful.