Bowlegs (genu varum)

Bowlegs, also known as genu varum, is a condition where the knees stay wide apart even when the ankles are touching, creating an outward curve in the legs. It's common in toddlers and often corrects on its own, but it can also persist or develop in older children and adults. When bowlegs cause pain or affect how you walk, our joint specialists can help you find the right path forward.

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Front-view medical illustration of bowlegs.

Anatomy of the knee

The knee joint connects the thighbone (femur) to the shinbone (tibia), with the kneecap (patella) resting in front to help protect the joint. Ligaments, cartilage and muscles work together to keep the knee stable and aligned as you move.

In a well-aligned knee, weight travels evenly through the joint. With bowlegs, the lower leg angles outward at the knee, shifting more weight onto the inner part of the joint. Over time, this uneven pressure can affect the knee's cartilage and surrounding structures.

Overview

Symptoms

Bowlegs are often noticeable simply by looking at how the knees and legs align. Common signs include:

A visible outward curve of the legs, even when standing with ankles together
A gap between the knees while standing
Uneven wear on the soles of shoes
Knee, hip or ankle pain, especially with activity
A waddling or awkward walking pattern in some cases

In children, mild bowlegs are common and often improves with growth. If the curve is severe, worsens over time or is only on one side, it's worth having it evaluated. In adults, bowlegs may progress gradually and lead to increasing knee discomfort.

Causes

Bowlegs can develop for several reasons, and the cause often depends on age. Common causes include:

Normal bone development in infants and toddlers, which usually resolves by age two or three
Blount's disease, a growth disorder affecting the shinbone in children
Rickets, caused by a vitamin D deficiency that softens bones
Untreated fractures that heal in a misaligned position
Osteoarthritis, which can gradually change knee alignment in adults
Certain bone or growth disorders

In some cases, the exact cause of bowlegs isn't clear, especially when it persists beyond early childhood without another identifiable condition.

Risk factors

Certain factors may make bowlegs more likely, though having one or more of these doesn't mean you or your child will develop the condition:

Being younger than two or three years old
A family history of bone or growth disorders
Vitamin D or calcium deficiency
Obesity, which places extra stress on the knees
Previous fracture or injury near the knee
Osteoarthritis in adulthood

Diagnosis

Diagnosing bowlegs typically begins with a physical exam to check leg alignment, gait and knee stability. Your doctor may also measure the distance between your knees while your ankles are together and ask about your growth history or any related symptoms. X-rays are often used to measure the angle of the legs and rule out underlying conditions such as Blount's disease or rickets. In some cases, blood tests may help identify a vitamin or bone health issue contributing to the curve.

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