Congenital malformation

Disease Description (Causes and Symptoms)

Congenital hand malformations refer to structural abnormalities of the hands and fingers resulting from abnormalities in development and differentiation during the embryonic period (usually weeks 6–8 of pregnancy), including polydactyly (multiple digits), syndactyly (webbed fingers), clinodactyly (curved fingers), congenital constriction ring syndrome (amniotic bands), cleft hand, and macrodactyly.
Summary of the main pathophysiology and causes:

• Abnormal segmentation of the fingers during the embryonic period (apoptosis and differentiation) → syndactyly (especially connection of the third and fourth digits), etc.
• Excessive segmentation and duplication signals → polydactyly.
• Local blood-flow impairment or compression (fetal constriction ring/amniotic band) → tissue defects, necrosis, and constriction ring syndrome.
• Combination of genetic and environmental factors: Depending on the report, hand malformations are observed in approximately 2–4% of newborns; approximately 20% are known to have genetic causes, 20% environmental causes, and 60% unknown causes. Syndactyly has been reported to occur in approximately 1 in 2,000 people, and polydactyly in approximately 1 in 400 people.
  Main symptoms:
• Fingers joined together (syndactyly): Ranges from simple forms in which only the skin is joined to complex forms in which the bones and joints are fused.
• Extra fingers (polydactyly): Ranges from a simple skin projection to a fully functional finger.
• Bending or deformity (clinodactyly, brachydactyly), trigger finger (limited flexion due to tendon abnormality), enlargement of a finger (macrodactyly), cleft hand, etc.
  The clinical effects may appear as functional limitations (grip and coordination) or mainly as cosmetic problems, depending on the type and severity of the deformity. The deformity may progress with growth, or secondary problems may develop.

Treatment Methods and Precautions

The goals of treatment are to restore form and function as close to normal as possible and to minimize secondary deformities associated with growth.

Main treatment principles

• Non-surgical observation: Observation may be appropriate when there is no functional impairment, such as in mild clinodactyly.
• Surgical correction: Most cases of syndactyly, polydactyly, and moderate or more severe deformities require surgical correction. Surgical procedures include excision, reconstruction (including correction of tendons, ligaments, and bones), and combination procedures (forming one finger from two fingers). If a skin defect occurs, a flap or skin graft is required (zigzag incision; skin grafting from areas such as the groin).
• Timing of procedures (general recommendations):
  • Congenital constriction ring (amniotic band): Immediately if finger survival is at risk; otherwise, surgery around 6 months of age.
  • Syndactyly: Surgery is generally performed at 1–2 years of age, but surgery before 1 year of age is recommended when involvement of the thumb or bony fusion is expected to interfere with growth. Simple, skin-only syndactyly can be treated around 12 months of age. When three or more fingers are joined, staged surgery is necessary.
  • Polydactyly: Surgery is usually performed around 12 months of age (generally around 1 year). Thumb polydactyly is complex and requires systematic reconstruction.
  • Clinodactyly and brachydactyly: Osteotomy or ligament surgery may be performed for severe angulation or functional impairment. This is generally considered after 4–6 years of age or when the child can cooperate.
• Anesthesia and hospitalization: General anesthesia and hospitalization are required. The operating time and length of hospitalization vary depending on the complexity of the deformity.
• Rehabilitation and follow-up: Sutures are removed after approximately 2 weeks; deep fixation (pins/cast) is maintained for 3–4 weeks, followed by physical therapy and friction massage (to prevent contracture at the skin-graft site) and long-term monitoring of growth. Additional corrective surgery may be required as the child grows.

Precautions and complications

• Scarring, web-creep (reconstruction of the space between the fingers), sensory changes, infection, joint stiffness, and possible recurrence of deformity with growth.
• The need for multiple secondary surgeries (follow-up through adulthood).
• Risk of infection and anesthesia before and after surgery, and differences in color and texture at the skin-graft site.
• The timing of surgery should be individualized by comprehensively considering functional benefits, effects on growth, and anesthesia risks.

Checklist Before an Outpatient Visit (Items to Prepare, Medical History Information, and Sample Questions)

Items/materials to bring

• List of current medications (for infants and young children, including breastfeeding and administered medications), and allergy history (especially allergies or reactions related to anesthesia).
• Birth and obstetric records (including ultrasound results) and family history (similar malformations or genetic diseases).
• Results of previous tests and imaging (hand X-rays, ultrasound, etc.) and photographs (front and side views of the hand and close-up photographs of the areas of connection).
• The child’s growth and developmental history (feeding, motor development, and ability to use the hand).
• Symptom diary (functional limitations, pain, color changes, sensory abnormalities, etc.).

Additional items to check during the consultation (information to tell the doctor)

• Whether the malformation is bilateral or unilateral, and whether it is symmetrical.
• Finger sensation and blood flow (pallor, bluish discoloration, temperature), and whether movement is limited.
• Movements that are difficult in daily life (gripping, picking up objects, buttoning clothes, etc.).
• Whether any family members have similar malformations or genetic diseases.

Examples of General Questions to Ask the Doctor

• How will this deformity affect function? Is surgery absolutely necessary?
• When is the recommended timing for surgery, and why?
• What will the expected surgical method, length of hospitalization, and type of anesthesia be?
• What are the major risks and complications of surgery, and how likely are they to occur?
• How will rehabilitation (physical therapy) and long-term follow-up proceed? How likely is additional surgery?
• When can the patient return to daily activities (kindergarten, school, and sports) after surgery?

Examples of Condition-Specific Questions

• Regarding syndactyly:
  • Are my fingers joined only by skin, or are the bones also connected? (Confirm with X-rays or other imaging.)
  • Is a skin graft necessary? How likely is it that the condition will not be resolved with one surgery?
• Regarding polydactyly (including thumb involvement):
  • After removing the extra finger, how will the shape and function of the thumb be reconstructed?
  • In cases of thumb polydactyly, is additional reconstruction likely to be needed during growth?
• Regarding congenital constriction ring (amniotic band):
  • Is the blood flow or sensation in the affected area currently impaired? Is immediate surgery necessary?

(Before or during the consultation, taking notes of the questions above or bringing photographs and test results can help with consultation and decision-making.)