Mateusz Gładysz FESSH prep

FESSH prep Congenital hand Wassel classification and frequency of types, laterality, triphalangeal component and inheritance, excision versus reconstruction, late revision

Radial polydactyly (thumb duplication)

Last reviewed v1.0

FESSH-059Congenital hand●○○ basic

Regarding radial polydactyly (thumb duplication):

  1. 1.In the Wassel classification, type IV — duplication at the level of the metacarpophalangeal joint — is the most common type.

  2. 2.Thumb duplication is bilateral in most affected children.

  3. 3.A triphalangeal thumb occurring with radial polydactyly is often familial, with autosomal dominant inheritance commonly caused by mutations in the long-range sonic hedgehog limb enhancer (ZRS).

  4. 4.In radial polydactyly, simple excision of the smaller radial thumb without reconstruction of the retained thumb rarely needs revision.

  5. 5.Most revisions after reconstruction of a duplicated thumb are performed within the first year after the index operation.

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Question ID
FESSH-059
First published
Last reviewed
Version
v1.0
Answer key and explanations — open after answering

  1. 1. In the Wassel classification, type IV — duplication at the level of the metacarpophalangeal joint — is the most common type.

    True

    The Wassel classification describes seven types by the level of duplication. In Wu's series of 2,300 duplicated thumbs type IV accounted for 40.2%, and Dijkman's review gives type IV 45%, type II 20% and type VII 15%.

    • Wu J, Shi W, Lin X, Li J, Yuan Z, Zhu M, et al.. Epidemiological characteristics and distribution of congenital thumb duplication in south China: An analysis of 2,300 thumbs in 2,108 children. Front Pediatr. 2022;10:1027243. PMID 36405832
    • Dijkman RR, van Nieuwenhoven CA, Hovius SE, Hülsemann W. Clinical Presentation, Surgical Treatment, and Outcome in Radial Polydactyly. Handchir Mikrochir Plast Chir. 2016;48(1):10-7. PMID 26895514

  2. 2. Thumb duplication is bilateral in most affected children.

    False

    Radial polydactyly is predominantly unilateral: Wu reported a unilateral-to-bilateral ratio of 10:1 in 2,108 children, and Lin's series had 373 unilateral and 55 bilateral cases. Bilateral cases had more associated anomalies and a positive family history more often.

    • Wu J, Shi W, Lin X, Li J, Yuan Z, Zhu M, et al.. Epidemiological characteristics and distribution of congenital thumb duplication in south China: An analysis of 2,300 thumbs in 2,108 children. Front Pediatr. 2022;10:1027243. PMID 36405832
    • Lin S, Tong K, Zhang G, Cao S, Zhong Z, Wang G. Clinical Characteristics and Distribution of Thumb Polydactyly in South China: A Retrospective Analysis of 483 Hands. J Hand Surg Am. 2020;45(10):938-946. PMID 32473835

  3. 3. A triphalangeal thumb occurring with radial polydactyly is often familial, with autosomal dominant inheritance commonly caused by mutations in the long-range sonic hedgehog limb enhancer (ZRS).

    True

    Gurnett identified ZRS point mutations in families with autosomal dominant triphalangeal thumb and preaxial polydactyly and concluded that ZRS mutations are a common cause of the familial form. Potuijt's open-access review considers triphalangeal thumb with radial polydactyly a predominantly inherited disease, in contrast to an isolated triphalangeal thumb, which is seen in both sporadic and familial cases. Not every family carries a ZRS mutation.

    • Gurnett CA, Bowcock AM, Dietz FR, Morcuende JA, Murray JC, Dobbs MB. Two novel point mutations in the long-range SHH enhancer in three families with triphalangeal thumb and preaxial polydactyly. Am J Med Genet A. 2007;143A(1):27-32. PMID 17152067
    • Potuijt JWP, Galjaard RH, van der Spek PJ, van Nieuwenhoven CA, Ahituv N, Oberg KC, et al.. A multidisciplinary review of triphalangeal thumb. J Hand Surg Eur Vol. 2018;44(1):59-68. PMID 30318985

  4. 4. In radial polydactyly, simple excision of the smaller radial thumb without reconstruction of the retained thumb rarely needs revision.

    False

    Ganley found that 5 of 6 thumbs treated by ablation alone needed further procedures for radial collateral ligament reconstruction, and Dijkman notes that mere excision often requires revision. The retained thumb is therefore reconstructed at the same operation, typically including the radial collateral ligament.

    • Ganley TJ, Lubahn JD. Radial polydactyly: an outcome study. Ann Plast Surg. 1995;35(1):86-9. PMID 7574294
    • Dijkman RR, van Nieuwenhoven CA, Hovius SE, Hülsemann W. Clinical Presentation, Surgical Treatment, and Outcome in Radial Polydactyly. Handchir Mikrochir Plast Chir. 2016;48(1):10-7. PMID 26895514

  5. 5. Most revisions after reconstruction of a duplicated thumb are performed within the first year after the index operation.

    False

    Stutz followed patients operated on at about 1 year of age for a mean of 17 years; 8 patients had 10 revision procedures at an average of 8 years after the initial operation. Hovius's review reports reoperation rates of 7–28% in long-term studies, mostly for deviation, instability or nail deformity, with unfavourable results often developing during growth and revealed only at longer-term follow-up.

    • Stutz C, Mills J, Wheeler L, Ezaki M, Oishi S. Long-term outcomes following radial polydactyly reconstruction. J Hand Surg Am. 2014;39(8):1549-52. PMID 24996673
    • Hovius SER, Kruit AS. Complications after radial polydactyly surgery: analysis, prevention and management. J Hand Surg Eur Vol. 2023;49(2):226-239. PMID 37917822