Genu Varum and Valgum in Children

Prepared and reviewed by the PrepElephant Academic Review Team

First published 14 Oct 2026 · Spot an error?

Reference basis: Maheshwari's Essential Orthopaedics; Apley's System of Orthopaedics and Fractures

On this page

Direct answer
What you must remember
Separating normal valgus from disease in a 4-year-old
Where the exam tries to catch you
Frequently asked questions
Related topics

Direct answer

Genu varum and genu valgum are normal developmental knee alignments in children, becoming pathological only when they persist beyond the expected age, become asymmetrical or progress. Physiological varus is maximal in infancy and usually resolves by 18 to 24 months, giving way to physiological valgus, which peaks around three to four years before correcting by about seven to eight years. The intermalleolar distance (valgus) and intercondylar distance (varus) are measured to separate normal alignment from disease.

What you must remember

Physiological varus: typical in infants and toddlers, maximal in infancy and usually self-correcting by 18 to 24 months.
Physiological valgus: appears around two to three years, peaks around three to four years and corrects by about seven to eight years.
Intercondylar distance: the gap between the knees with the ankles together, used to quantify genu varum.
Intermalleolar distance: the gap between the ankles with the knees together, used to quantify genu valgum; values persistently above the usual age range suggest pathology.
Red flags: asymmetry, progression, persistence beyond about eight years, short stature, pain and a limp point to disease.
Differential: rickets, Blount disease, skeletal dysplasias and post-traumatic physeal injury must be excluded in a pathological case.
Management: physiological alignment needs reassurance and review; pathological deformity is treated by addressing the cause, with guided growth or osteotomy where indicated.
Measurement: a standing full-length radiograph gives the hip-knee-ankle alignment when clinical measurement is uncertain.

Separating normal valgus from disease in a 4-year-old

A 4-year-old boy has knock knees that look worse on the left, with normal height. The approach separates age-related valgus from a pathological deformity.

Check the age window: valgus at this age is usually physiological, so the parent's concern is first tested against the normal pattern for the child's age.
Measure the distances: the intermalleolar distance (for valgus) is measured with the child standing, and the values are compared with age-based norms rather than a single cut-off.
Look for asymmetry and progression: one leg worse than the other, or a deformity that worsens between visits, is a warning sign that changes the plan.
Assess the whole child: height, gait, pain, limb length and the bones are examined, since short stature suggests a skeletal or metabolic cause.
Image if red flags are present: standing full-length radiographs measure the alignment and show physeal or metaphyseal change.
Treat the cause: physiological deformity is observed with reassurance, while pathological deformity is treated by addressing the underlying disease, with guided growth or osteotomy where needed.

Where the exam tries to catch you

Examiners test the normal age-related pattern and the red flags that signal disease.

Trap: labelling a 2-year-old's bow legs as pathology. Correct: physiological varus is normal in infants and toddlers up to about 18 to 24 months, so reassurance and review are appropriate unless red flags are present.
Trap: ignoring unilateral genu valgum or varum. Correct: asymmetry and progression suggest Blount disease, post-traumatic physeal injury or another growth-plate problem and need radiography.
Trap: relying on a single distance measurement alone. Correct: the intermalleolar or intercondylar distance must be read against the child's age and the degree of alignment, since a single measurement can mislead.

Frequently asked questions

At what age does physiological genu varum change to normal valgus?

Physiological varus is typical in infancy and toddlerhood, maximal early and resolving by 18 to 24 months, and transitions to physiological valgus around two to three years of age. Varus resolving by 18 to 24 months is the expected state and is observed.

Which features suggest pathological genu varum or valgum in a child?

Asymmetry, progression, persistence beyond about eight years, short stature, pain and a limp suggest a pathological cause. Blount disease, rickets, skeletal dysplasia and post-traumatic physeal injury must then be excluded.

What do the intercondylar and intermalleolar distances measure?

The intercondylar distance is the gap between the knees with the ankles touching, while the intermalleolar distance is the gap between the ankles with the knees touching. The intercondylar distance quantifies genu varum and the intermalleolar distance quantifies genu valgum, and both are compared with age-based norms, since textbooks quote different cut-offs.

How is persistent genu valgum in a child managed?

Physiological valgum is observed, while pathological valgum is treated according to its cause, with guided growth or osteotomy when indicated. Timing depends on the remaining growth and the severity of the deformity, so an orthopaedic review is essential.