title: Cleft hands with six metacarpals.
abstract: OBJECTIVE
  The purpose of this study was to identify children with cleft hands whose radiographs showed metacarpal polydactyly with 6 metacarpals to support the hypothesis that cleft hand develops not as a result of a longitudinal failure of formation but through a process of central polydactyly and osseous syndactyly.
  
  
  METHODS
  We screened the hand radiographs of all children with a transverse or longitudinal deficiency of the upper limb and identified 8 children with cleft hands containing 6 metacarpals.
  
  
  RESULTS
  Six cleft hands had a missing middle finger and consisted of a thumb and index finger separated from the ring and small fingers by a V-shaped central cleft. Two children had a more severe form of cleft hand with absence of both the index and middle fingers but presence of 6 metacarpals.
  
  
  CONCLUSIONS
  These 8 cleft hands containing 6 metacarpals showed progression of polydactyly of the middle finger and osseous syndactyly between the 2 middle finger metacarpals and the adjacent index and ring finger metacarpals. This contradicts a longitudinal failure of formation mechanism and supports the alternative hypothesis that cleft hand, polydactyly, and syndactyly develop through a similar teratogenic mechanism. The 2 cleft hands that had more severe suppression of the index and middle fingers yet had 6 metacarpal polydactyly provided confirmatory evidence that both typical cleft hands and the more severe manifestations of cleft hand with absence of multiple digits develop through a similar failure of induction mechanism.
authors.affiliation: UCLA Hand Center, Department of Orthopaedic Surgery and Division of Plastic and Reconstructive Surgery, University of California, Los Angeles 90095-9607, USA.
authors.forename: Neil F
authors.initials: NF
authors.lastname: Jones
authors.forename: Michiyuki
authors.initials: M
authors.lastname: Kono
mesh_terms: D002648:Child; D006801:Humans; D008663:Metacarpus / Q000002:abnormalities*; D017689:Polydactyly / Q000000981:diagnostic imaging* / Q000196:embryology; D011859:Radiography; D013576:Syndactyly / Q000000981:diagnostic imaging* / Q000196:embryology