Growth

    Knock-knees and Bow legs: Crooked Legs in Children

    X-shaped or O-shaped legs, normal ages 2-7. Seek evaluation if marked asymmetry or ankle distance >8cm after age 7. Milan visit.

    Medically reviewed: May 2026·Dott. Daniele Priano

    Quick Answers

    Is it normal for a child to have crooked legs?
    Yes, angular deviations of the knee are normal during growth. Bow legs are typical in the first years of life, while knock-knees are common in preschool and school age. Most cases resolve spontaneously.
    When should I worry about knock-knees?
    An evaluation is advised if the valgus appears markedly increased, asymmetric between the two limbs, worsening rather than improving with growth, or if it causes pain, fatigue or gait difficulty.
    Do braces or special shoes correct crooked legs?
    No, there is no scientific evidence that braces, orthopaedic shoes or insoles correct physiological knee deviations. Correction occurs naturally with growth. Only in selected pathological cases may a specific orthopaedic plan be indicated.
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    Crooked legs — knock-knees (genu valgum) and bow legs (genu varum) — are part of the normal evolution of lower limb alignment during growth. In the first years of life, a varus appearance typically prevails, gradually giving way to a valgus phase in preschool and school age, until final alignment is reached in later childhood.

    In the great majority of cases this is a physiological, self-limiting picture that resolves spontaneously with bone growth, without the need for corrective devices, insoles or braces. A markedly increased deviation, asymmetry between the two limbs or progressive worsening is, however, a signal that deserves a clinical evaluation.

    During the visit we observe posture, gait and limb axis, ruling out secondary causes (nutritional deficiencies, bone disorders, post-traumatic changes) and agreeing with the family on an appropriate observation plan. Only in selected situations — marked deviations or significant evolutive potential — is a targeted correction considered.

    Dott. Daniele Priano - Ortopedico Pediatrico

    🦵Children's Legs Change

    Knock knees ('X-shaped') are physiological between ages 3-7, just as bow legs ('O-shaped') are normal in the first 2 years. These are developmental patterns that correct spontaneously in most cases. I evaluate if it's within normal range for age or requires further investigation.

    When to seek evaluation

    • Varus persisting beyond 2-3 years
    • Marked valgus beyond 7-8 years (IMD > 8 cm)
    • Significant asymmetry between the two legs
    • Progressive worsening deviation
    • Pain or gait disturbances

    What is evaluated

    • Intercondylar distance (ICD) measurement for varus
    • Intermalleolar distance (IMD) measurement for valgus
    • Mechanical axis evaluation of lower limbs
    • Gait and posture examination
    • Weight-bearing lower limb X-rays when indicated
    • Exclusion of pathological forms (rickets, dysplasias)

    Treatment options

    • Observation and follow-up in most cases
    • Periodic photographic and clinical monitoring
    • Guided temporary hemiepiphysiodesis (growth modulation) in selected cases
    • Corrective osteotomy in severe forms
    🏥

    When Surgery Is Needed

    La grande maggioranza delle deviazioni del ginocchio in età pediatrica si corregge spontaneamente con la crescita. Tuttavia, in casi selezionati di deformità persistenti, patologiche o progressive, può essere considerato un trattamento chirurgico.
    🔗View surgical options for this condition →

    Types and Normal Values

    🦵Genu Varum (Bow Legs)

    The knees are apart while the ankles touch. Physiological in the first 2 years of life. Measured by the intercondylar distance (ICD): the distance between the internal femoral condyles with ankles together.

    Normal Evolution:

    0-18 monthsICD up to 5-6 cmPhysiological varus, normal during this period
    18-24 monthsICD < 3 cmProgressive correction toward neutral
    > 2 yearsICD = 0Varus should be resolved; if it persists, evaluate

    🦵Genu Valgum (Knock Knees)

    The knees touch while the ankles are apart. Physiological between 3 and 6-7 years. Measured by the intermalleolar distance (IMD): the distance between the internal malleoli with knees together.

    📏 IMD (Intermalleolar Distance): measured in cm with knees in contact

    Normal Evolution:

    3-4 yearsIMD up to 6-8 cmPeak of physiological valgus
    5-6 yearsIMD 4-6 cmProgressive spontaneous correction
    7-8 yearsIMD < 2-3 cmFinal alignment reached; if IMD > 8 cm, evaluate
    > 10 yearsIMD < 2 cmComplete correction; if it persists, consider treatment

    Frequently Asked Questions

    Is it normal for a child to have crooked legs?▼
    Yes, angular deviations of the knee are normal during growth. Bow legs are typical in the first years of life, while knock-knees are common in preschool and school age. Most cases resolve spontaneously.
    When should I worry about knock-knees?▼
    An evaluation is advised if the valgus appears markedly increased, asymmetric between the two limbs, worsening rather than improving with growth, or if it causes pain, fatigue or gait difficulty.
    Do braces or special shoes correct crooked legs?▼
    No, there is no scientific evidence that braces, orthopaedic shoes or insoles correct physiological knee deviations. Correction occurs naturally with growth. Only in selected pathological cases may a specific orthopaedic plan be indicated.
    Are crooked legs hereditary?▼
    There is a familial component: children whose parents had a similar alignment may show a more evident or slower-to-correct picture. However, family history alone does not indicate a pathology — clinical evaluation remains the reference point.
    My child plays sports: are knock-knees or bow legs a problem?▼
    In the vast majority of cases, no. Sports are actually encouraged because they support good muscular and proprioceptive development, useful for limb maturation. In markedly increased or symptomatic forms we discuss possible adjustments together, without forbidding physical activity.
    Is there an age by which crooked legs must be corrected?▼
    There is no rigid deadline that fits everyone. In general, knee alignment stabilizes in later childhood: if at that point the deviation remains significant or continues to worsen, an in-depth evaluation may be appropriate. Deciding case by case, considering remaining growth and the clinical picture, is the most appropriate approach.
    Can the pubertal growth spurt worsen knock-knees?▼
    In some children, the pubertal growth spurt can temporarily increase an existing valgus because bone growth accelerates exactly when the growth plate is most reactive. For this reason the pre-pubertal and pubertal windows are useful clinical checkpoints to re-evaluate limb alignment and, when indicated, plan a minimally invasive correction guided by remaining growth — an option that is no longer available once skeletal maturity is reached.
    What is a weight-bearing lower limb X-ray for?▼
    A weight-bearing lower limb X-ray (taken standing, with the child loading the leg) allows measurement of the true mechanical axis, distinguishing femoral, tibial or combined valgus and ruling out pathological causes (rickets, dysplasia, post-traumatic sequelae). It's a targeted exam, requested only when the clinical evaluation suggests an evolving picture, and is not part of routine screening.
    What's the difference between hemiepiphysiodesis and adult corrective surgery?▼
    **Temporary hemiepiphysiodesis** (growth modulation with eight-plates) is a minimally invasive pediatric technique: a small plate selectively slows one side of the growth plate and correction occurs gradually, using remaining growth. Immediate weight-bearing, no cast, plate removed once correction is achieved. In adults the growth plate is closed, so an osteotomy (cutting and realigning the bone) is required, with longer and more demanding recovery. That's why, when indicated, acting within the pediatric window is technically advantageous.
    How long is follow-up after a diagnosis of genu valgum or varum?▼
    In physiological cases, a clinical check every 6-12 months is enough until alignment stabilizes. In active observation or hemiepiphysiodesis treatment, checks are closer together to monitor correction speed and decide the optimal timing for plate removal. The plan is always individual: visit frequency is agreed during the consultation.

    Important Notice: The information on this page is for educational and informational purposes only and does not constitute medical advice. Each clinical case is unique: the appropriate treatment is determined during the specialist consultation, based on a thorough clinical examination and, where necessary, diagnostic imaging. For any doubts or concerns, please consult a specialist.

    Learn more

    Video

    Knock-knees and Bow legs: Crooked Legs in Children

    Surgery

    Surgical options

    Exercises

    Home exercises

    Home Exercises

    Download the exercise sheet for this condition

    View exercises

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    Bowlegs or Knock-knees in Early Childhood

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    Dott. Daniele Priano

    Are your child's crooked legs worrying you?

    For information or questions, contact me.

    PrenotaContatti

    Email: daniele.priano@ortopediaevolutiva.com

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