Background
Polydactyly is the most common congenital anomaly of the forefoot.[1, 2, 3, 4, 5, 6, 7]
Images of polydactyly are provided below:
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. 
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. 
Preoperative photograph of a 1-year-old child with preaxial polydactyly and significant varus of the duplicated toe. 
Preaxial polydactyly with longitudinal bracket epiphysis. Recent studies
Hikosaka et al described open treatment for syndactyly of the foot on 16 webs. The authors stated that open treatment is better than skin grafting because of a better match of skin texture without the creation of a patchwork-looking scar. They explained that open treatment is indicated in cases of simple, incomplete syndactyly of the foot extending proximally to the distal interphalangeal joint and noted that grafting results in an additional scar at the donor site and the patchwork-looking scar at the recipient site.[8]
Adam et al observed clinical findings in 18 cases of diabetic embryopathy and preaxial hallucal polydactyly to identify the features most suggestive of diabetic embryopathy. Preaxial hallucal polydactyly was present in all 18 cases (7 bilateral, 11 unilateral); other findings included spinal segmentation anomalies, equinovarus deformity of the feet, tibial hemimelia, hip dysplasia, and femoral hypoplasia. Of the 18 mothers, 11 had prepregnancy insulin-dependent diabetes; 1 had prepregnancy type 2 diabetes requiring insulin in the third trimester; 5 had gestational diabetes requiring insulin; and 1 had gestational diabetes controlled by diet. The authors found that proximally placed preaxial hallucal polydactyly, particularly when coupled with segmentation anomalies of the spine and tibial hemimelia, is highly suggestive of diabetic embryopathy. They added that diabetes in the mothers pointed to a possible genetic predisposition interacting with teratogenic effects of poor glycemic control.[9]
History of the Procedure
Treatment for polydactyly of the foot has changed little over time. Removing the extra digit by disarticulation is the standard treatment.[3, 10, 11, 12]
Problem
Polydactyly most commonly refers to the presence of 6 toes on one foot, but more toes are possible. Polydactyly may be associated with syndactyly. It most frequently occurs as an isolated trait with autosomal dominant inheritance and variable penetrance. Other patterns of inheritance,[13] sporadic occurrence, and association with syndromes are also possible.[1, 14, 15]
Epidemiology
Frequency
Incidence is 1.7 cases per 1000 live births. Incidence is higher in blacks (3.6-13.9 cases per 1000 live births) than in whites (0.3-1.3 cases per 1000 live births).
Etiology
Polydactyly may occur as an isolated trait or in conjunction with certain syndromes, and there is a positive family history in 30% of cases. The syndromes with which polydactyly has been associated include Ellis-van Creveld syndrome,[16, 17] trisomy 13, tibial hemimelia, and trisomy 21. Polydactyly is bilateral in 50% of cases and has a slight male predilection.
Pathophysiology
Postaxial polydactyly (lateral ray) is the most common polydactyly,[6] occurring in 80% of cases, followed by preaxial polydactyly (medial) and then central polydactyly. The duplication may range from a well-formed articulated digit to a rudimentary digit. Abnormalities of the associated metatarsal commonly occur in polydactyly. A morphologic classification was described by Venn-Watson,[1] as shown in the image below:
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:
- Normal metatarsal with distal phalanx duplication
- Block metatarsal
- Y-shaped metatarsal
- T-shaped metatarsal
- Normal metatarsal shaft with wide head
- Duplicated ray
A first metatarsal bracket epiphysis (longitudinal epiphyseal bracket) may occur in preaxial polydactyly.[18]
Presentation
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.
Indications
Surgery is indicated to improve cosmesis and to improve shoe fit. It is usually performed when the patient is aged approximately 1 year, so the effect on development and walking is minimal. Surgery should be delayed until skeletal development (ossification) has occurred within the affected rays so that accurate anatomic assessment is possible.
Relevant Anatomy
See Intraoperative details.
Contraindications
No absolute contraindications to surgery exist. However, parents may choose not to excise the duplicate digit for personal reasons.
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Lee HS, Park SS, Yoon JO, Kim JS, Youm YS. Classification of postaxial polydactyly of the foot. Foot Ankle Int. May 2006;27(5):356-62. [Medline].
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Adam MP, Hudgins L, Carey JC, Hall BD, Coleman K, Gripp KW, et al. Preaxial hallucal polydactyly as a marker for diabetic embryopathy. Birth Defects Res A Clin Mol Teratol. Jan 2009;85(1):13-9. [Medline].
Lim YJ, Teoh LC, Lee EH. Reconstruction of syndactyly and polysyndactyly of the toes with a dorsal pentagonal island flap: a technique that allows primary skin closure without the use of skin grafting. J Foot Ankle Surg. Mar-Apr 2007;46(2):86-92. [Medline].
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Auyeung J, Bhattacharya R, Birla R, Hide G, Henman P. The occult toe: an unusual case of polydactyly in the foot. J Pediatr Orthop B. Aug 24 2009;[Medline].
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Yucel A, Kuru I, Bozan ME, Acar M, Solak M. Radiographic evaluation and unusual bone formations in different genetic patterns in synpolydactyly. Skeletal Radiol. Aug 2005;34(8):468-76. [Medline].
Nelman K, Weiner DS, Morscher MA, Jones KC. Multiplanar supramalleolar osteotomy in the management of complex rigid foot deformities in children. J Child Orthop. Feb 2009;3(1):39-46. [Medline].
Leeson MC, Wilcox PG, Weiner DS. Congenital duplication of the foot and toes. Foot Ankle. Jan-Feb 1985;5(4):191-7. [Medline].
Weaver KM, Henry GW, Reinker KA. Unilateral duplication of the great toe with anterolateral tibial bowing. J Pediatr Orthop. Jan-Feb 1996;16(1):73-7. [Medline].
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