Postaxial polydactyly

Last revised by Rohit Sharma on 23 Apr 2024

Citation, DOI, disclosures and article data

Citation:

Weerakkody Y, Sharma R, Juan-Sierra D, et al. Postaxial polydactyly. Reference article, Radiopaedia.org (Accessed on 25 Apr 2024) https://doi.org/10.53347/rID-15588

DOI:

https://doi.org/10.53347/rID-15588

Permalink:

https://radiopaedia.org/articles/15588

rID:

15588

Article created:

27 Oct 2011, Yuranga Weerakkody ◉

Disclosures:

At the time the article was created Yuranga Weerakkody had no recorded disclosures.

View Yuranga Weerakkody's current disclosures

Last revised:

23 Apr 2024, Rohit Sharma ◉

Disclosures:

At the time the article was last revised Rohit Sharma had no financial relationships to ineligible companies to disclose.

View Rohit Sharma's current disclosures

Revisions:

33 times, by 22 contributors - see full revision history and disclosures

Systems:

Musculoskeletal, Paediatrics, Obstetrics

Sections:

Syndromes

Tags:

embryology

Synonyms:

Polydactyly - post axial
Post axial polydactyly
Post-axial hyperdactyly
Post-axial polydactyly

Postaxial polydactyly refers to polydactyly where the additional digit is on the ulnar margin of the hand, or lateral to the 5^th(little) toe.

Epidemiology

Postaxial polydactyly is more common than preaxial polydactyly, with an estimated incidence of 1 in 3000 ⁵.

Associations

trisomy 13
Bardet-Biedl syndrome
Meckel Gruber syndrome
McKusick-Kaufman syndrome
following oral-facial-digital syndromes (OFDS)
- oral-facial-digital syndrome (OFDS) type II (Mohr syndrome)
- oral-facial-digital syndrome (OFDS) type VI
certain skeletal dysplasias
- chondroectodermal dysplasia (Ellis-van Creveld syndrome)
- asphyxiating thoracic dysplasia (Jeune syndrome)
Smith Lemli Opitz syndrome
certain short rib polydactyly syndromes: e.g. types I and III

Pathology

The majority of cases are idiopathic. Associations with mutations to the GLI3 gene on chromosome 7 as well as a second locus mapped to chromosome 13 have been implicated in postaxial polydactyly ⁵.

Classification

Several different classification systems exist for postaxial polydactyly of the hands, including the Pritsch, Rayan and Al-Qattan, and Duran classification systems.

Duran et al. introduced their classification system for post-axial polydactyly in 2015 ⁶. This classification was created as it was felt that the previous systems in use were not comprehensive for coverage of the different post-axial forms.

type I: skin nub without nail or bone elements
type II: hypoplastic proximal phalanx
type III: proximal phalangeal malformations
- IIIa: bifid proximal phalanx
- IIIb: duplicated proximal phalanx
type IV: metacarpal malformations
- IVa: fusion of the metacarpal
- IVb: bifid metacarpal
- IVc: duplication of the metacarpal
type V: (complicated type) with triplication of the small finger, polysyndactyly, or both

References

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