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Little girl with bow legs or knocked knees

Should I be worried about my child’s bowlegs or knocked-knees?

Parents will often express concern at our visits about their child being “bow-legged” or “knock-kneed.” The medical term for being bow-legged is genu varum. This means the knees seem to bow outward, away from each other. Genu valgum is the opposite, meaning knock-kneed, or that knees point inward toward each other. Both of these are part of normal growth and development in children and very few kids ever require treatment.

The muscles of the legs are very tight in certain areas at birth due to how babies are positioned in the womb. Genu varum and valgum are a result of these muscles growing, stretching and finding balance in the first few years of life.

Children will typically begin to appear bow-legged around the time they are learning to stand and walk. After 2 years, we see toddlers start to look more knock-kneed, which will progress until age 4. At this time, the legs gradually grow to reach a more neutral alignment around age 7.


If children are following this expected pattern, no additional testing is needed. In caring for my patients and their families who have concerns about these issues, I am vigilant about looking for anything that might be reason for concern, such as:

  • The curvature is extreme

  • Only one side is affected

  • The bow-legs persist after 2 years of age

  • The knock-knees persist after age 7

  • The child is not meeting expected growth

If any of these features are observed, we may recommend additional testing, such as an X-ray, or in rare cases, referral to an orthopedic or other specialist may be needed.

Rarely, bowlegs or knock-knees are the result of a disease. Arthritis, injury to the growth plate around the knee, infection, tumor, Blount’s disease (a growth disorder of the shinbone), and rickets all can cause changes in the curvature of the legs, which may require doctor recommended intervention.

If you as a parent have any concerns about your child’s growth and development, it is always a good idea to bring it up with your Children’s Wisconsin primary care doctor.