How should I evaluate and manage an 8‑month‑old infant with a rounded, inward‑turned foot (suspected metatarsus adductus)?

Management of an 8-Month-Old with Inward-Turned Foot (Metatarsus Adductus)

Initial Assessment

For an 8-month-old infant with a rounded, inward-turned foot consistent with metatarsus adductus, immediate treatment with serial casting or orthotic devices is indicated if the deformity is moderate-to-severe or rigid, as spontaneous resolution becomes less likely after 5 months of age and treatment outcomes are superior when initiated before 9 months. 1, 2

Key Clinical Evaluation Points

• Assess flexibility: Gently abduct the forefoot while stabilizing the hindfoot. Flexible deformities correct passively; rigid deformities do not 3, 4
• Evaluate severity using the heel bisector line (HBL): Draw an imaginary line bisecting the heel—if it passes lateral to the 4th toe, the deformity is severe; between 3rd and 4th toes indicates moderate severity 1
• Check for asymmetry: Unilateral or asymmetric findings are red flags requiring urgent evaluation to exclude neurological or skeletal dysplasia 5, 6
• Examine the hindfoot: Metatarsus adductus has a normal hindfoot; if hindfoot abnormalities exist, consider alternative diagnoses 3, 4

Treatment Algorithm

For Flexible Metatarsus Adductus

• No active treatment is recommended for flexible deformities, as strong evidence supports spontaneous resolution 3
• Encourage barefoot walking indoors to promote normal foot development 6
• Recommend flexible, well-fitted shoes outdoors with flat heels and adequate toe room 6

For Moderate-to-Severe or Rigid Metatarsus Adductus

At 8 months of age with rigid or moderate-to-severe deformity, initiate treatment immediately, as outcomes deteriorate significantly after 9 months and the deformity may become fixed and require surgery if left untreated. 1, 2, 4

Treatment Options (in order of preference):

1. Universal Neonatal Foot Orthosis (UNFO) or similar below-ankle orthotic:

   • Applied for 23 hours daily until complete correction achieved 1
   • Effective in 87% of cases (98/114 feet) with severe deformity 1
   • Shorter full-time treatment duration compared to casting 2
   • Fewer social burdens and greater convenience than serial casting 2

2. Serial casting:

   • Standard alternative if orthotic devices unavailable 3, 2
   • Requires cast changes every 1-2 weeks 4
   • Equally effective to UNFO but less convenient 2

3. Observation only if:

   • Deformity is flexible AND
   • Parents understand that 8% of cases persist and may require surgery if spontaneous correction doesn't occur by age 7 7

Critical Pitfalls to Avoid

• Do not delay treatment beyond 9 months of age: Treatment initiated after this age has significantly worse outcomes, and the deformity becomes increasingly fixed 1, 2, 4
• Do not assume all cases resolve spontaneously: While many flexible cases do, moderate-to-severe and rigid deformities rarely correct without intervention 3, 4, 7
• Do not miss asymmetric findings: Unilateral presentation requires urgent evaluation to exclude neurological causes or skeletal dysplasia 5, 8
• Do not rely on special footwear alone: Corrective shoes without orthotic support are ineffective for rigid deformities 3, 7

When to Refer

• Immediate pediatric orthopedic referral if:
  • Rigid deformity present at 8 months 1, 2
  • Asymmetric findings suggesting underlying pathology 5, 8
  • Associated limb deformities or skeletal dysplasia suspected 6
  • Failed conservative management or recurrence after initial correction 2, 4

Follow-Up Protocol

• Monitor treatment progress every 2-4 weeks until complete correction 1
• Continue follow-up until walking age to assess for recurrence 1, 2
• Begin weaning from orthotic only after complete correction achieved 1
• Recurrence rates are low (approximately 3-4%) with appropriate treatment compliance 2