What causes bow legs in children and when is treatment needed?

Bow legs in children, medically known as genu varum, are a common concern for parents of young children. While it can look alarming, in many cases it forms part of normal development. However, there are situations where bow legs may indicate an underlying condition requiring specialist care.

What are bow legs?

Bow legs describe a condition where a child’s legs curve outward at the knees while the ankles remain together. This appearance is particularly noticeable when a child begins to stand and walk.

In early childhood, some degree of bowing is entirely normal. Babies are often born with bow legs due to their position in the womb, and this usually improves naturally as they grow.

Common causes of bow legs in children

The most common cause of bow legs in children is normal growth. In most children:

• Bowing is seen in infancy and toddler years.
• Legs gradually straighten by around 18–24 months.
• Alignment may then shift slightly to “knock knees” before settling into normal adult alignment.

This type of genu varum does not require treatment.

Blount’s disease

Blount’s disease is a growth disorder affecting the shin bone (tibia), leading to progressive bowing of the legs. It is more likely to:

• Affect one leg more than the other.
• Worsen over time rather than improve.
• Occur in children who started walking early or are above average weight.

Early diagnosis is important, as treatment for bow legs may be needed to prevent long-term deformity.

Rickets (vitamin D deficiency)

Rickets is a condition caused by insufficient vitamin D, calcium, or phosphate, leading to soft and weak bones. Signs may include:

• Bowed legs.
• Delayed growth.
• Bone pain or weakness.

This condition is treated medically, often with supplements.

Other less common causes

Less commonly, bow legs in children may be due to:

• Genetic or skeletal disorders.
• Previous injury or infection affecting bone growth.

These cases require specialist assessment.

When should parents be concerned about bow legs?

While most cases of bow legs in children resolve naturally, the following signs suggest that medical review is needed:

• Bowing that persists beyond the age of 2–3 years.
• Worsening curvature over time.
• Asymmetry (one leg more bowed than the other).
• Associated pain, limp, or difficulty walking.
• Short stature or delayed growth.

If any of these are present, referral to a paediatric orthopaedic specialist is recommended.

When is treatment needed for bow legs?

For physiological bow legs, the appropriate approach is reassurance and monitoring. No braces, special shoes, or exercises are required. Historically, bracing was sometimes used for bow legs; however, studies have shown that it is not effective and is no longer recommended.

If rickets or another metabolic condition is identified, treatment focuses on correcting the underlying deficiency.

Surgical treatment

In cases such as Blount’s disease or persistent deformity, surgery may be considered. Options include:

• Guided growth: a minimally invasive technique to gradually correct alignment in growing children.
• Corrective osteotomy: realignment of the bone in more severe or advanced cases.

The choice of bow legs treatment depends on the child’s age, severity of bowing, and underlying cause.

Bow legs in children are often a normal part of development and resolve without intervention. However, persistent, worsening, or asymmetrical bow legs may indicate an underlying condition requiring treatment.

If you are concerned about your child’s leg alignment or development, consult with consultant paediatric orthopaedic and limb reconstruction surgeon Mr Jonathan Wright via his Top Doctors profile to ensure accurate diagnosis and timely management to support healthy growth and alignment.