Updated: 10/31/2016

Congenital Clasped Thumb

Review Topic
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  • Congenital flexion-adduction deformity of the thumb that persists beyond the 3rd or 4th month of life
  • Epidemiology
    • demographics
      • male-to-female ratio is approx 2.5:1
    • risk factors
      • exact causative factors are not well known
      • possible pre-disposing factors include
        • consanguinity
        • family history
  • Pathophysiology
    • genetics
      • autosomal dominance inheritance of variable expressivity 
      • may be sporadic 
    • pathoanatomy
      • attenuation or deficiency of EPB (more common, in mild cases) or EPL, or both
      • associated with 1st web contracture 
      • contracture of adductor pollicis or first dorsal interosseous muscle
      • global instability of first MP joint
      • abnormal articular cartilage of first MP joint
  • Orthopedic considerations
    • common manifestations associated with disease
      • lower limb anomalies
        • congenital vertical talus
        • congenital talipes equinovarus (bilateral)
      • upper limb anomalies
        • flexion deformities of the four fingers
  • Associated conditions
    • arthrogryphosis (congenital joint contractures affect two or more areas in the body)
    • digitotalar dysmorphisms
    • Freeman-Sheldon syndrome
    • X-linked MASA syndrome

Type I (Supple clasped thumb)

Thumb can be passively abducted and extended against resistance of thumb flexors. No other digital anomaly present.

Type II (Clasped thumb with contracture)

Thumb cannot be passively extended and abducted. This may occur with or without other digital anomaly.

Type III  (Rigid clasped thumb)

Clasped thumb that is associated with arthrogryposis and marked soft-tissue deficits.
  • History
    • persistent flexion-adduction deformity beyond 3rd or 4th month of life, usually bilateral
    • family history
    • pre-natal history
  • Symptoms
    • pain usually with a contracture
    • associated with other musculo-skeletal deformities
  • Examination
    • type of clasped thumb
    • associated anomalies
  • Nonoperative
    • serial splinting and stretching for 3-6 months
      • indications
        • first-line treatment for all types 
        • begin treatment around the age of 6 month old
      • outcome
        • good definitive results with Type I congenital deformities when one of the EPL or EPB tendons are present
        • poor results with Type I deformities when both EPL/EPB tendons are absent
        • poor results with Type II or III deformities
  • Operative
    • EIP tendon transfer to EPL
      • indications
        • Type I or II with residual deficiency in active extension
      • technique
        • EIP transfer to remnant of extensor tendon
    • thumb reconstruction
      • indications
        • failed conservative treatment
        • soft-tissue deficiency in the thumb-index finger webspace (Type III)
        • Type II or III deformity with significant MCP joint contractures 
      • technique
    • arthrodesis
      • indications
        • severe deformities when skin release and tendon trasnfer cannot overcome joint deformity.
  • Thumb reconstruction
    • delayed until the age of 3 to 5 years old
    • procedure based on amount of contracture and may include
      • 1st web widening
        • transposition flap of skin (dorsal rotational advancement flap)
        • four-flap or five-flap Z plasty 
      • deepening the first webspace by releasing soft-tissue 
        • releasing origins of thenar musculature from transverse carpal ligmant
        • releasing joint capsule of first MP joint
      • tendon transfer
        • FPL Z-lengthening in the forearm
        • EPB and EPL absence is best reconstructed with tendon transfer
          • isolated EPB absence will not usually require tendon transfer
  • Cosmetic appearance
  • Instability of the MP joint
  • Reduced thumb function

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(OBQ05.224) A 8-month-old male presents with the hand deformity seen in Figure A. Examination reveals restrictions in passive extension and abduction of the thumb. His mother tells you that her other two children had similar deformities that required operative management. What would you offer as the first-line treatment option for this child's deformity? Review Topic | Tested Concept

QID: 1110





Serial splinting of thumb




Thumb-index finger web space reconstruction




Thenar muscle tendon transfer




First metacarpophalangeal joint arthrodesis



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