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Updated: Apr 30 2023

Polydactyly of Hand

Images
https://upload.orthobullets.com/topic/6079/images/Preaxial Polydactyly - clinical image_moved.jpg
https://upload.orthobullets.com/topic/6079/images/wassel deformity.jpg
https://upload.orthobullets.com/topic/6079/images/Duplicate thumb 1 - colorado_moved.jpg
https://upload.orthobullets.com/topic/6079/images/wasseltypeii.jpg
https://upload.orthobullets.com/topic/6079/images/Duplicate thumb 2 - colorado_moved.jpg
https://upload.orthobullets.com/topic/6079/images/capture_type_3.jpg
  • summary
    • Polydactyly of Hand is a congenital malformation of the hand that presents with an extra digit in the hand.
    • Diagnosis is made clinically.
    • Treatment is usually a form of surgical reconstruction depending on the level of duplication and the specific digit involved.
  • Etiology
    • Forms
      • preaxial polydactlyly
        • thumb duplication
      • postaxial polydactlyly
        • small finger duplication
      • central polydactlyly
  • Preaxial Polydactyly (Thumb Duplication)
    • Epidemiology
      • incidence
        • 1 per 1,000 to 10,000 live births
        • Type IV most common (43%)
        • Type II second most common (15%)
      • demographics
        • M>F
        • caucasian > African Americans
    • Genetics
      • inheritance pattern
        • usually unilateral and sporadic
        • except for Type VII which is associated with several syndromes including
          • Holt-Oram syndrome
          • Fanconi's anemia
          • Blackfan-Diamond anemia
          • imperforate anus
          • cleft palate
          • tibial defects
    • Associated conditions
      • pollex abductus
        • abnormal connection between EPL and FPL tendons, seen in approximately 20% of hypoplastic and duplicated thumbs
        • suggested by abduction of affected digit + absence of IP joint crease
    • Classification
      • Wassel Classification of Preaxial Polydactyly
      • Type I
      • Bifid distal phalanx
      • Type II
      • Duplicated distal phalanx
      • Type III
      • Bifid proximal phalanx
      • Type IV
      • Duplicated proximal phalanx (most common)
      • Type V
      • Bifid metacarpal
      • Type VI
      • Duplicated metacarpal
      • Type VII
      • Triphalangia
    • Treatment
      • operative
        • goals of treatment
          • to construct a thumb that is 80% of the size of the contralateral thumb
          • resect smaller thumb (usually radial component)
          • preserve / reconstruct medial collateral structures in order to preserve pinch function
          • reconstruction of all components typically done in one procedure
        • type 1 combination procedure (Bilhaut-Cloquet)
          • indications
            • type I, II, or III
          • technique
            • involves removing central tissue and combining both digits into one
          • outcomes
            • approximately 20% have late deformity
            • problems include stiffness, angular and size deformity, growth arrest, and nail deformities
        • type 2 combination procedure
          • indications
            • usually favored approach for type III and IV
            • type V and VI usually require more complex transfer of intrinsics and collateral ligaments
          • technique
            • preserve skeleton and nail of one component and augment with soft tissue from other digit and ablation of lesser digit (radial digit most commonly)
        • type 3 combination procedure
          • indications
            • when one digit has superior proximal component and one digit has superior distal fragment (type V, VI, and VII)
          • technique
            • a segmental distal transfer (on-top plasty)
  • Postaxial Polydactyly (Small Finger Duplication)
    • Epidemiology
      • demographics
        • 10X more common in African Americans
    • Genetics
      • inherited as autosomal dominant (AD) in African Americans
      • more complex genetics in caucasians
        •  thorough genetic workup should be performed to evaluate for chondroectodermal dysplasia or Ellis-van Creveld syndrome
    • Classification
      • Type A - well formed digit
      • Type B - rudimentary skin tag (vestigial digits)
    • Treatment
      • operative
        • formal reconstruction with a Type 2 combination
          • indications
            • Type A
          • technique
            • preserve radial digit
            • preserve or reconstruct collateral ligaments from ulnar digit remnant
            • preserve muscles
        • tie off in nursery or amputate before 1 year of age
          • indications
            • Type B
  • Central Polydactyly
    • Epidemiology
      • commonly associated with syndactyly
        • extra digit may lead to angular deformity or impaired motion
    • Treatment
      • osteotomy and ligament reconstructions
        • indications
          • perform early to prevent angular growth deformities
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