What is the treatment approach for a toddler with bow legs (genu varum)?

Management of Bow Legs (Genu Varum) in Toddlers

Most cases of bow legs in toddlers represent physiologic genu varum that will spontaneously resolve without intervention by 3 years of age and require only observation and regular follow-up. 1

Understanding Bow Legs in Toddlers

Bow legs (genu varum) in toddlers is a common condition characterized by outward bowing of the legs. There are two main types:

1. Physiologic Genu Varum:

   • Most common type (majority of cases)
   • Typically presents when children begin walking (around 10-15 months) 1
   • Spontaneously resolves with growth and maturity of lower extremities 2

2. Pathologic Genu Varum:

   • Less common but requires intervention
   • Includes conditions like infantile Blount's disease (tibia vara), metabolic disorders, and genetic conditions

Diagnostic Approach

Clinical Assessment:

• Measure the distance between the knees when ankles are together
• Perform the "cover up test": Cover the thigh and look at proximal tibia alignment
  • Negative test (valgus alignment): Suggests physiologic bowing
  • Positive test (neutral or varus alignment): Higher risk for infantile tibia vara 3

When to Consider Radiographs:

• Children with positive "cover up" test
• Persistent bowing beyond expected age of resolution
• Asymmetric bowing
• Progressive worsening of the deformity
• Family history of bone disorders

Laboratory Testing:

• Consider vitamin D testing as recent evidence suggests that "physiologic" genu varum may be associated with vitamin D disorders
• Blood tests for serum calcium, alkaline phosphatase, and parathyroid hormone may be warranted 4

Management Protocol Based on Age and Presentation

For Children Presenting Before 18 Months:

• Observe for initial signs of correction between 18-24 months
• Expect resolution by 30 months
• Follow-up during well-child visits 1

For Children Presenting Between 18-23 Months:

• Observe for initial signs of correction between 24-30 months
• Expect resolution by 36 months
• Follow-up during well-child visits 1

For Children Presenting at 24 Months or Older:

• More careful evaluation is needed
• Consider radiographic assessment if bowing is significant or asymmetric

Treatment Recommendations

For Physiologic Genu Varum:

• Reassurance to parents about spontaneous resolution
• Regular monitoring during well-child visits
• No braces, special shoes, or exercises are needed 5

For Pathologic Genu Varum:

• Referral to pediatric orthopedic specialist
• Treatment depends on underlying cause:
  • Infantile Blount's disease: May require bracing or surgery
  • Metabolic disorders (rickets): Vitamin D supplementation
  • Genetic conditions: Specific management based on diagnosis

Vitamin D Considerations:

• Consider vitamin D testing and supplementation as recent research shows association between vitamin D insufficiency/deficiency and genu varum in toddlers 4

Follow-up Protocol

• Use fingerbreadth measurements to document progression or resolution during well-child visits
• For physiologic cases: Follow-up at regular well-child visits until resolution
• For suspected pathologic cases: More frequent follow-up and referral to orthopedics

When to Refer to Orthopedic Specialist

• Positive "cover up" test
• Persistent bowing beyond expected age of resolution (30-36 months)
• Worsening deformity
• Asymmetric bowing
• Associated symptoms or abnormal gait

Important Considerations

• Children with physiologic genu varum often walk earlier than average (10 months vs 12-15 months) 1
• Avoid unnecessary radiographs for typical physiologic bowing to prevent radiation exposure
• The primary goal is distinguishing between physiologic bowing (requiring observation) and pathologic conditions (requiring intervention)

By following this protocol, primary care providers can effectively manage most cases of bow legs in toddlers while appropriately identifying those who need specialist referral.