Genu Varum (Bowed legs)

Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.
Title: 5-Minute Orthopaedic Consult, 2nd Edition
> Table of Contents > Genu Varum (Bowed legs)

Genu Varum (Bowed legs)
Paul D. Sponseller MD
  • The knee goes through normal phases of
    changing alignment in childhood: Genu varum (bowed legs) is physiologic
    in infants and young children up to 2 years of age, and its appearance
    is maximal at 12–18 months of age (13).
  • Bowing is most obvious when children start walking.
  • It may be combined with internal tibial torsion, which makes it appear more pronounced.
  • Bowing may seem greater with weightbearing.
  • This condition usually resolves by 2 years of age and changes to physiologic genu valgum (knock-knee) (2).
  • Tibia vara (Blount disease) (see “Blount Disease
    chapter), rickets, fibrocartilaginous dysplasia of the proximal tibia,
    and other genetic disorders can cause pathologic genu varum (Fig. 1-1).
  • Physiologic (normal) bowing is ~1,000 times more common than pathologic bowing (e.g., Blount disease) (1,3).
  • It occurs equally in boys and girls.
Risk Factors
Family history
  • Some causes of bowed legs are familial:
    • Blount disease
    • Renal rickets
    • Skeletal dysplasia
      Fig. 1. Patient with severe untreated infantile varus now in adolescence.
  • Bowing is an imbalance between the load and growth plate development.
  • It may be caused by:
    • Overweight
    • Rickets (4)
    • Skeletal dysplasia
  • Physiologic causes: Normal growth
    patterns of the femoral and tibial growth plates include a period of
    normal varus in early infancy.
  • Pathologic causes:
    • Tibia vara (Blount disease)
    • Rickets (nutritional or renal)
    • Achondroplasia
    • Epiphyseal and metaphyseal dysplasias
    • Focal fibrocartilaginous dysplasia
  • In most of these conditions, the varus results from inability of the growth plate to respond normally to load (3).
Associated Conditions
  • Early walker
  • Heavy weight
Signs and Symptoms
  • Parental concern about the appearance of the legs is the most common reason for the presentation of children.
  • The patient should be pain free; if pain exists, another cause should be sought.
  • Genu varum may develop spontaneously in
    the overweight adolescent who previously had straight legs (adolescent
    Blount disease), and it usually requires treatment (Fig. 2).
If a patient has physiologic bowing, the parents should start to notice improvement after the 2nd birthday (3).
Fig. 2. 13-year-old boy with adolescent genu varum. Note the widened medial physis.
Physical Exam
  • Obtain a medical, family, and developmental history.
  • Determine the patient’s height and weight percentiles.
  • Estimate the angulation of the knee.
  • Check the rotation of the tibia and femur.
  • To monitor the patient’s progress, document the distance between the medial surfaces of the knees (intercondylar distance) (5,6).
  • In routine cases, tests are not indicated if varus appears mild and physiologic.
  • If metabolic causes are suspected, serum
    calcium, phosphate, alkaline phosphatase, 1,25-vitamin D, and
    creatinine levels may be measured (3,4).
  • Radiographic evaluation of bowed legs in
    children <18 months old should be reserved for asymmetric bowing or
    for patients suspected of having a pathologic condition other than
    benign physiologic varus.
  • A single AP radiograph of the lower
    extremity from hip to ankle on a standing film is the most appropriate
    1st imaging study; care should be taken that the knee is pointing
    straight ahead.
  • Widening of physis suggests rickets;
    delayed ossification of the distal femoral and proximal tibial
    epiphyses may be a result of excessive pressure on 1 side of the knee.
  • The femorotibial angle and the metaphyseal–diaphyseal angle of the tibia should be measured (5).
  • If the metaphyseal–diaphyseal angle is <11°, physiologic bowing is assured.
  • If the metaphyseal-diaphyseal angle is >16°, the child has Blount disease.
  • If the metaphyseal bowing in the femur is
    equal to or greater than that in the tibia, the bowing is more likely
    to be physiologic (1) (Fig. 3).
    3. This 2-year-old patient had bowed legs. The metaphyseal–diaphyseal
    angle is 10° on each side. The bowing is more pronounced on the femoral
    than the tibial metaphysis. It resolved without treatment.


Differential Diagnosis
  • Achondroplasia
  • Rickets
  • Infantile or adolescent Blount disease
  • Metaphyseal or epiphyseal dysplasia
General Measures
  • Physiologic conditions:
    • Physiologic bowing always resolves without treatment; bracing is not needed
    • At ≥18 months of age, follow-up
      examination and imaging are needed to differentiate physiologic bowing
      from tibia vara (may be difficult) (6).
  • Pathologic conditions:
    • Rickets or other metabolic bone disease:
      • The underlying disease is treated, with osteotomy reserved for those patients with persisting varus after treatment.
    • Achondroplasia and epiphyseal or metaphyseal dysplasia:
      • The patient may need surgical treatment, depending on the degree of deformity.
    • Tibia vara (Blount disease):
      • Brace treatment is appropriate for children <3 years old; a knee-ankle-foot brace may be used for walking.
      • If the patient is >4 years of age, osteotomy is recommended.
Special Therapy
Physical Therapy
  • Not necessary for physiologic bowing
  • Not an effective treatment for pathologic varus
  • Many different types of osteotomy are
    available for correcting varus deformity, including dome, oblique,
    closing wedge, or opening wedge osteotomy.
  • The tibia or the femur may require surgery, depending on the site of the deformity.
  • Physeal bar resection or hemiepiphysiodesis may be indicated for some cases.
  • Physiologic genu varum has an excellent prognosis for spontaneous improvement.
  • The prognosis of pathologic genu varum varies.
  • Knee pain and worsening of the bow are likely in adulthood if the deformity is >10–15° (5).
  • Untreated genu varum may cause pain on the medial part of the knee and eventual arthritis during adulthood.
  • Adolescent genu varum may be painful.
  • Complications occasionally seen from surgery may include:
    • Infection
    • Compartment syndrome
    • Recurrence of deformity
    • Growth disturbance
Patient Monitoring
  • The frequency of follow-up varies, depending on the individual surgeon or pediatrician.
  • Physiologic bowing does not need frequent
    follow-up unless the condition is not improving; resolution is a slow
    process and may take a year.
  • Pathologic bowing needs more prolonged follow-up.
1. Bowen
RE, Dorey FJ, Moseley CF. Relative tibial and femoral varus AS a
predictor of progression of varus deformities of the lower limbs in
young children. J Pediatr Orthop 2002;22:105–111.
2. Salenius P, Vankka E. The development of the tibiofemoral angle in children. J Bone Joint Surg 1975;57A:259–261.
3. Schoenecker PL, Rich MM. The lower extremity. In: Morrissy RT, Weinstein SL, eds. Lovell and Winter’s Pediatric Orthopaedics, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2006:1157–1211.
4. Biser-Rohrbaugh A, Hadley-Miller N. Vitamin D deficiency in breast-fed toddlers. J Pediatr Orthop 2001;21:508–511.
5. Gordon JE, King DJ, Luhmann SJ, et al. Femoral deformity in tibia vara. J Bone Joint Surg 2006;88A:380–386.
6. Langenskiold A. Tibia vara. A critical review. Clin Orthop Relat Res 1989;246:195–207.
736.42 Genu varum
Patient Teaching
  • Parents should be told that physiologic
    genu varum will resolve spontaneously and slowly; if it is not starting
    to improve at least by 2–3 years of age, additional evaluation is
  • No restriction on activity is recommended.
  • Exercises do not help genu varum resolve.
Q: Do infant “jumper” devices contribute to bowed legs?
A: No evidence suggests that they do. The children are supported in these devices, so the load on the legs is controlled.

Q: When should a child with bowing be referred to a specialist?
A: If the bowing gets worse after 18 months or persists after the 2nd birthday.

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