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Which of the following congenital hand deformities displayed in figures A-E is more prevalent in patients of African-American ancestry?
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Image B is consistent for postaxial polydactyly, which is more prevalent in patients of African-American ancestry.
The cohort study by Woolf found the incidence of postaxial polydactyly in African americans is 12.42 per 1,000 (1.2%) compared to the Caucasian incidence of 0.91 per 1,000 (0.09%). If postaxial polydactyly is found in a patient of Caucasian ancestry then further workup for underlying syndromes (chondroectodermal dysplasia or Ellis-van Creveld syndrome) is needed.
The article by Orioli is a case-control study that hypothesizes that a sex-linked recessive modifier gene occurs more frequently in African americans and this gene then promotes the autosomal dominant polydactyly gene.
Incorrect Answers: Constriction band syndrome or amniotic band syndrome is a type of pseudosyndactyly (Figure A) and is not the result of failure of differentiation during embryogenesis, but a result of injury by bands after the fingers are formed. Preaxial polydactyly (Figure C) is more common in caucasians and is usually sporadic except for triphalangism which is associated with Holt-Oram and Fanconi's Anemia. Syndactyly (Figure D) is defined as an abnormal interconnection between adjacent digits and syndactyly variations are associated with Apert syndrome and Poland syndrome. Macrodactyly (Figure E) represents overgrowth of all structures of the involved digit and is associated with neurofibromatosis and Klippel-Trenaunay-Weber syndrome.
Am J Hum Genet. 1995 May;56(5):1207-11. PMID: 7726178 (Link to Abstract)
Woolf CM, Myrianthopoulos NC.
Am J Hum Genet. 1973 Jul;25(4):397-404. PMID: 4351996 (Link to Abstract)
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The Bilhaut-Cloquet procedure for thumb duplication, where the central portions of bone and nail are removed and the radial half of one thumb is combined with the ulnar half of the other to create one thumb, is most appropriate in which Wassel Type shown in Figure A?
The Bilhaut-Cloquet procedure has been shown to be successful in Wassel Type 1, 2, and 3 deformities. Asymmetrical Type I or II duplications with distinct components may also be treated with ablation of the smaller thumb with transfer of the collateral ligament and centralization of the extensor tendon. Types 3 and 4 duplications (Type 4= most common duplication) are often treated with selection of a dominant thumb and ablation of the lesser counterpart after preservation and transfer of intrinics and collateral ligaments.
The article by Ogino states that the ablation of the radial thumb is most common and Miller's Review states radial thumb ablation is preferred. Treatment of Types 5 and 6 duplication utilizes similar principles as Type 4 deformities, with the added complexity of additional intrinsic reconstruction. Type 7 is a triphalangeal thumb and has variable treatment based on the presentation, and reconstruction includes excision versus fusion of the extra phalanx.
Baek el al conducted a Level 4 review of 7 patients with Type 3 and Type 4 duplication treated with an extra-articular modified Bilhaut-Cloquet and found excellent IP joint range of motion, no nail deformities, and no episodes of growth arrest.
Ogino T, Ishii S, Takahata S, Kato H
J Hand Surg Am. 1996 May;21(3):478-86. PMID: 8724483 (Link to Abstract)
Baek GH, Gong HS, Chung MS, Oh JH, Lee YH, Lee SK
J Bone Joint Surg Am. 2007 Mar;89(3):534-41. PMID: 17332102 (Link to Abstract)
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Which of the following upper extremity congenital anomalies, represented in the figures below, if found in an individual of Caucasian descent requires a work-up for chondroectodermal dysplasia or Ellis-van Creveld syndrome?
Postaxial polydactyly is rare in Caucasian individuals and deserves further workup for underlying syndromes. Postaxial polydactyly is ten times more common in African Americans and does not require further workup. Constriction band syndrome or amniotic band syndrome is a type of pseudosyndactyly(Figure A) and is not the result of failure of differentiation during embryogenesis, but a result of injury by bands after the fingers are formed. Preaxial polydactyly (Figure C) is more common in Caucasians and is usually sporadic except for triphalangism which is associated with Holt-Oram and Fanconi's Anemia. Syndactyly (Figure D) is defined as an abnormal interconnection between adjacent digits and syndactyly variations are associated with Apert syndrome and Poland syndrome. Macrodactyly (Figure E) represents overgrowth of all structures of the involved digit and is associated with neurofibromatosis and Klippel-Trenaunay-Weber syndrome. The referenced article by Kozin is an excellent Current Concepts Review that summarizes upper limb embryogenesis and the most common anomalies.
J Bone Joint Surg Am. 2003 Aug;85-A(8):1564-76. PMID: 12925640 (Link to Abstract)
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