Type a ulnar polydactyly of the hand: A classification system and clinical series

Tamir Pritsch, Marybeth Ezaki, Janith Mills, Scott N. Oishi

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Purpose: To propose a classification system for type A ulnar polydactyly based on radiographic findings and characterize the demographic features of patients with these deformities. Methods: We identified 49 patients with type A ulnar polydactyly of the hand who were seen in our institution over 20 years. Patients' medical records and radiographs were retrospectively reviewed and used to distinguish morphological subtypes. Results: Ninety-six percent of the deformities (64/67) were allocated to 1 of the 5 subgroups of our suggested classification, and the type that originated from the metacarpophalangeal joint was the most common. Sixty-nine percent of patients in our series (34/49) had either bilateral type A or a contralateral type B ulnar polydactyly, and 63% (31/49) had ulnar polydactyly of one or both feet. Twenty-four percent of patients (12/49) had associated syndromes or congenital anomalies involving areas other than the hand or foot. The most common syndrome associated with type A ulnar polydactyly was chondroectodermal dysplasia (n = 3). Sixty-five percent of the patients (32/49) were Caucasian, 20% were Hispanic (10/49), 12% were African American (6/49), and one was Asian. The percentage of African Americans in our series was similar to that in the general patient population seen in our institution. Conclusions: The majority of type A ulnar polydactyly can be classified into 1 of 5 morphological subtypes that have potential clinical relevance regarding surgical treatment. In patients with type A ulnar polydactyly, contralateral hand and foot polydactyly is frequent. Associated congenital anomalies and syndromes can also be present. Type of study/level of evidence: Prognostic IV.

Original languageEnglish (US)
Pages (from-to)453-458
Number of pages6
JournalJournal of Hand Surgery
Issue number3
StatePublished - Mar 1 2013


  • Classification
  • polydactyly
  • postaxial
  • small finger
  • type A

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine


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