Figure 1. Radiograph of the hands.
A 6-month-old infant is brought to the office by his parents who describe an extra digit over the small finger on each hand. He had a normal prenatal course and delivery and has no other known medical issues. On examination he is a healthy-appearing infant. Floppy duplicated fingers are identified on the proximal phalanges of both small fingers. A radiograph of bilateral hands is obtained (Figure). Both bony and nail portions are present. The patient’s other fingers appear normal.
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Polydactyly presents as an extra finger or toe that ranges in size from a small bump to a complete working digit. Preaxial polydactyly occurs on the thumb or radial side, and postaxial polydactyly occurs on the ulnar side of the limb (also known as small finger duplication). Postaxial polydactyly is 10 times more common in African Americans while preaxial polydactyly (thumb duplication) is more common in white individuals.1 The extra digit is often referred to as a “supernumerary” digit.
When the supernumerary digit presents as a small nubbin, it can be treated by tying the base of the digit with a suture in the nursery; this causes the digit to turn gangrenous and fall off. A larger or near-normal digit requires surgical ablation usually at 6 to 9 months of age before fine motor skills have developed and when anesthesia is safer to administer. Complications from treatment may include a residual nubbin and infection.1,2
Polydactyly is usually sporadic, not associated with a syndrome, and generally occurs unilaterally. However, the more complex the polydactyly is the more likely the patient has an associated syndrome.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
1. Faust KC, Kimbrough T, Oakes JE, Edmunds JO, Faust DC. Polydactyly of the hand. Am J Orthop (Belle Mead NJ). 2015;44(5):E127-E134.
2. Kozin S. Upper-extremity congenital anomalies. J Bone Joint Surg Am. 2003;85(8):1564-1576.