What is the management approach for an infant with polydactyly (extra digit)?

Management of Polydactyly in Infants

Infants with polydactyly should be referred to a pediatric plastic surgeon for evaluation and management. 1

Types and Prevalence

Polydactyly (extra digit) is one of the most common congenital limb malformations in infants. It can be classified into several types:

• Postaxial polydactyly (extra digit on the little finger/toe side):
  • Type B: Most common form, with a vestigial sixth digit attached by a narrow neurovascular pedicle 2
  • Type A: Fully developed extra digit with bifid metacarpal/metatarsal 2
• Preaxial polydactyly (extra digit on the thumb/big toe side)
• Central polydactyly (duplication of middle digits)

Epidemiology:

• More common in males than females 2
• Higher prevalence in Black infants (0.91/100) compared to White infants (0.035/100) 2
• More frequently affects hands than feet 2
• Can be unilateral or bilateral, with unilateral being more common 3

Diagnostic Evaluation

When evaluating an infant with polydactyly:

1. Physical examination:

   • Determine the type of polydactyly (postaxial, preaxial, or central)
   • Assess whether the extra digit is fully formed or rudimentary
   • Evaluate for associated anomalies that might suggest a syndrome

2. Family history:

   • Approximately 10-15% of isolated polydactyly cases are inherited 3
   • Inheritance pattern is typically autosomal dominant with variable expressivity 2

3. Imaging:

   • Radiographs may be needed to determine the extent of skeletal involvement
   • Important for surgical planning to identify shared joints or tendons

Management Approach

1. Initial Assessment

• Determine if polydactyly is isolated (95% of cases) 2 or part of a syndrome
• If multiple anomalies are present, consider genetic evaluation

2. Surgical Management

For postaxial type B polydactyly (most common type):

• Simple ligation at the base of the pedicle may be performed for very rudimentary digits
• Formal surgical excision is preferred for better cosmetic outcomes and to prevent neuroma formation

For fully formed digits (postaxial type A, preaxial, or central):

• Surgical excision by a pediatric plastic surgeon is required 1
• Timing: Usually performed between 6-12 months of age when anesthesia risks are lower but before significant body image development

3. Referral Guidelines

According to the American Academy of Pediatrics guidelines:

• "Infants and children with congenital malformations of the limbs (eg, syndactyly, polydactyly) should be referred to a pediatric plastic surgeon." 1

4. Postoperative Care

• Regular wound care to prevent infection
• Follow-up to monitor healing and functional outcomes
• Assessment of any functional limitations as the child develops

Special Considerations

• Syndromic associations: When polydactyly is associated with other anomalies, a more comprehensive genetic evaluation is warranted
• Bilateral involvement: May indicate higher likelihood of genetic etiology 3
• Functional impact: Preaxial and central polydactyly often have greater functional implications than postaxial type B

Prognosis

• Isolated postaxial polydactyly type B has excellent outcomes with appropriate surgical management
• More complex forms may require multiple procedures and have variable functional outcomes
• Early intervention provides better cosmetic and functional results

Surgical removal of the extra digit is the definitive treatment for polydactyly, with timing and technique determined by the specific type and complexity of the condition.