KidsMD Health Topics


  • Overview

    Children with bowlegs, when standing straight with toes pointed forward, have ankles that touch but knees that do not. Bowlegs is a condition involving the shin and thigh (tibia and femur) bones. Having bowlegs is considered a normal part of growth in young children, as are "knock-knees," in which both knees point inward. Bowlegs usually go away on their own by the time your child is four or five years old, or sometimes as old as eight years old.

    But if your child remains bowlegged, it may be a sign of an underlying bone disease, such as Blount's disease or rickets, which is caused by a Vitamin D deficiency.

    How Boston Children's Hospital approaches bowlegs

    Bowlegs cannot be corrected permanently without first treating the underlying cause for the condition. In the meantime, doctors at Children's try to make sure that your child's legs can straighten themselves naturally. If this doesn't work, doctors may require your child to wear corrective leg braces. Only the most severe cases would require surgery.

    Boston Children's Hospital
    300 Longwood Avenue
    Fegan 2
    Boston MA 02115

  • In-Depth

    Should I be concerned with my baby's progress in walking?

    Below are considered average developmental milestones in your baby's ability to walk:

    • 6-10 months – most babies learn to pull themselves up to a standing position.
    • 7-13 months – most babies will be moving about while holding on to furniture for support. Babies can walk with support from a parent (but don't force them into walking on their own).
    • 11-14 months – most babies will start to walk on their own, usually by 14 months.

    Your child, like most children, was probably born with bowlegs, which usually straighten themselves out as your child gets older.

    What causes bowlegs?

    Most often, bowlegs develop as part of natural growth, although certain conditions, such as Blount's disease and bone malformations present at birth, may cause a child's legs to bow. In Blount's disease, your child's shin bone (tibia) grows abnormally, causing a sharp curve below the knees. A child with Blount's disease is forced to walk with the affected knee flexed, which increases bowing of the leg. This can lead to severe knee joint problems. Blount's disease is more likely to affect female children, African-American children, obese or short children, or children who walk at an early age.

    Some metabolic disorders, such as rickets, a disease caused by Vitamin D deficiency, can also cause bowlegs. This occurs when Vitamin D deficiency affects and weakens a child's bones, causing the legs to bow.

  • Tests

    How does a doctor know my child has bowlegs?

    Bowlegs are obvious when a child stands with legs straight and toes pointed forward. Your child's physician can determine the severity of bowlegs by observing the position of a child's legs, knees, and ankles and by measuring the distance between the knees. The doctor will also want to observe your child while walking, both coming and going, to assess the degree of internal rotation.

    To document the positioning of the bowlegs and to look for any underlying bone deformities, your child's doctor may recommend X-ray films of the knees. During infancy, however, there is no clear distinction between Blount's disease and natural bowing. If your child is under 15 months of age, the X-ray can document the degree and location of bowing, but cannot be used to distinguish natural bowing from Blount's disease until the baby is older.

  • Specific treatment for bowlegs will be determined by your child's physician based on: 

    • your child's age, overall health, and medical history
    • the extent of the condition
    • the cause of the condition
    • your baby's tolerance for specific medications, procedures, or therapies
    • expectations for the course of the condition
    • your opinion or preference

    Depending on your child's age, the doctor will probably advise delaying treatment of bowlegs to give leg bones a chance to straighten naturally.

    If bowing of the legs does not correct itself, or increases after a child has been walking for some time, a physician may recommend corrective appliances.

    • Night braces help to pull the legs slowly into a straighter position.
    • Bowlegs caused by an underlying disease cannot be corrected completely until the disease itself is treated.
    • A child usually wears a corrective brace during part of the treatment of the disease.
    • If bowing is severe, your child's doctor my recommend an osteotomy, an operation on the upper part of the shinbone that would correct the lower limb alignment.

    Treatment of Blount's disease usually involves a combination of non-operative measures that include wearing a special brace and osteotomy. This brace, known as a modified knee-ankle-foot orthosis (KAFO) is designed to prevent knee flexion and must be worn day and night (23 hours a day). This brace works by releasing the compression forces in the area of the knee to allow the resumption of normal growth. Young children with the disease may not need surgery if the brace alone corrects the problem.

    Rickets can be corrected by adding vitamin D and calcium to the diet.

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