History and Physical Examination
The patient may present in infancy or at a later date when cosmesis or shoe fit becomes a concern. Obtain a thorough family history, and exclude association with syndromes. Perform a thorough musculoskeletal examination to exclude any other congenital anomalies or signs that occur with known syndromes.
Classification
A morphologic classification of polydactyly was described by Venn-Watson (see the image below). [3]
The Venn-Watson classification of polydactyly is based on the anatomic configuration of the metatarsal and the duplicated bony parts.
The Venn-Watson classification is based on the configuration of the metatarsal, as follows:
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Normal metatarsal with distal phalanx duplication
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Block metatarsal
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Y-shaped metatarsal
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T-shaped metatarsal
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Normal metatarsal shaft with a wide head
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Duplicated ray
A first metatarsal bracket epiphysis (longitudinal epiphyseal bracket) may occur in preaxial polydactyly. [25]
Several decades later, Seok et al developed a classification system for polydactyly of the foot that was intended to help determine surgical plans and predict outcomes. [26] This system consists of the following components:
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Three characters (S, indicating syndactylism; A, indicating axis deviation; and M, indicating metatarsal extension
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Three numbers (0, 1, and 2, indicating the degree of complexity of the polydactyly)
For example, the designation S1A1M2 in this system would indicate a case in which syndactylism to the adjacent toe was incomplete with the webbing involving less than half the length of the involved digits, the angulation was 15° or greater but less than 30°, and the metatarsal extension involved the shaft and more. [26]
Burger et al developed a classification system for medial foot polydactyly (the Rotterdam Foot Classification) that was based on the following four categories of anatomic features of the foot [27] :
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Duplication type
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Syndactyly
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Presence of a hypoplastic ray
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Deviation of the hallux
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The Venn-Watson classification of polydactyly is based on the anatomic configuration of the metatarsal and the duplicated bony parts.
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Postaxial polydactyly in a 1-year-old child. In this case, the duplicated sixth toe was excised (dotted line), and the broad distal fifth metatarsal was narrowed.
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Postoperative view of 1-year-old child who had postaxial polydactyly and excision of the sixth toe demonstrates a good result with straight lateral border.
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Preoperative photograph of a 1-year-old child with preaxial polydactyly and significant varus of the duplicated toe.
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Postoperative radiograph of a 1-year-old child with preaxial polydactyly who had significant varus of the duplicated toe demonstrates a good result after resection and metatarsal narrowing.
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Preaxial polydactyly with longitudinal bracket epiphysis.
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Mother and son with polydactyly. The patterns of deformity are different.
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Image of an 8-year-old boy with a history of bilateral preaxial polydactyly. He had excision of bilateral duplicated digits at an outside institution.
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Postoperative radiograph of an 8-year-old boy with a history of bilateral preaxial polydactyly and excision of the duplicated digits at an outside institution. He required additional surgery because of residual deformity. A good result is depicted following combination of the first metatarsal base with the second metatarsal shaft, creating a 5-digit foot.
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Radiograph depicting a patient who had a history of bilateral preaxial polydactyly and excision of bilateral duplicated digits at an outside institution. He required additional surgery at age 8 years. Good results were obtained following combination of the first metatarsal base with the second metatarsal shaft, creating a 5-digit foot. At 20-year follow-up, the patient is doing well.
