Bow Legs and Knock Knees

Legs are typically bowed in infancy, straighten around the second year, pass through a knock-kneed phase in the preschool years, and reach the adult alignment by around age seven 1. A child following that pattern needs reassurance, not treatment.

Braces, special shoes and insoles do not change physiological alignment. They are still sold widely for it, which is why families arrive having spent money on them.

One leg affected and not the other. Bowing that worsens after age two or knock knees worsening after age seven 1. A child noticeably short for their age. Pain, a limp, or a family history of bone disease. Any of these warrants imaging and blood tests.

The conditions being looked for are Blount disease, rickets and other metabolic bone disease, and growth plate injury. These are uncommon but they do not correct themselves and they progress.

In the child with a genuine structural problem, therapy supports the orthopaedic plan: strength and gait work around bracing or surgery, and gait analysis to document what is actually happening rather than what a photograph suggests.

In the much larger group with normal variation, our contribution is an assessment, an explanation and no treatment. That is a legitimate outcome and we will say so.

Bow legs are normal up to around two years, knees then move into knock-knee which peaks around three to four, and alignment settles by about seven 1. Most referrals are this normal sequence.

What is not normal is asymmetry, severe deformity, short stature alongside it, pain, or a pattern that is worsening rather than following the curve.

Most children with bow legs or knock knees measure within the normal range for their age, and these variations resolve as the child grows; X-rays are not needed routinely, only to rule out a disease cause 2. Tests are warranted when the deformity is severe or one-sided, or a metabolic or hormonal cause is suspected 2. Vitamin D and calcium deficiencies, which cause rickets, are still common worldwide, and rickets is preventable 3.

Surgery is kept for legs that do not straighten with growth or are markedly angled 2. In a child who is still growing, the usual operation is guided growth: a small plate or screws hold one side of the growth plate so the leg straightens gradually as it grows 4. In children whose deformity was caused by rickets, full correction took on average between 10.8 and 22.7 months, and regular follow-up is needed because the leg can over-correct or drift back 5.