What Causes Bow Legs?

The pattern over time matters more than appearance alone: a clinician considers age, symmetry, walking, pain, growth and whether the curve is improving or becoming more noticeable.

Bow legs, also called genu varum, describe an outward curve in which the knees remain apart when the feet and ankles are together. In babies and young toddlers, this often comes from the position of the legs before birth and the normal way alignment changes as bones grow.

Less commonly, bowing is linked to altered growth near the knee, including Blount disease, or to bones weakened by rickets. Previous injury, infection or another skeletal condition may also change how one or both legs grow. These causes cannot be distinguished reliably from photographs alone.

Notice whether both legs look similar and whether the curve is gradually easing. Record changes with occasional photographs taken in the same standing position, and mention any limp, pain or difficulty keeping up with usual play.

Do not start braces, special shoes, supplements or corrective exercises without an assessment. A clinician may examine hip, knee and ankle alignment, observe walking, review growth and diet, and request imaging or blood tests when the pattern suggests a bone or growth disorder. Treatment targets the cause rather than the visible curve alone.

Arrange an assessment if only one leg is bowed, one side is clearly worse, the curve is worsening, or it persists beyond the stage when a young child's legs would be expected to straighten. Pain, limping, reduced activity, poor growth or widening around the wrists or ankles also deserves review.

Seek prompt care after an injury or if the child cannot bear weight. Fever with a hot, red or swollen joint needs urgent medical attention because infection or another acute problem must be excluded.

Ask whether the alignment fits the child's growth stage, whether both legs are developing similarly, and which changes should trigger follow-up. If testing is proposed, ask what suspected cause each test is intended to check. If treatment is needed, discuss whether it addresses movement, bone health or growth-plate alignment.