TEACHING POINTS
■ Polydactyly, derived from the Greek words poly for many and dactylos for digit, describes supernumerary digits on the hands or feet.
■ Although its exact incidence is unknown, the condition is estimated to occur in 1 of every 500 live births. It is the most common congenital malformation in men, women, and cats.
■ Polydactyly can occur either with or without associated major birth defects, called syndromic or isolated polydactyly, respectively.
■ Because polydactyly is highly associated with teasing and taunting in children and many African tribes believe the condition is a sign of being cursed, surgery as early in infancy as possible is the recommended treatment of choice. Surgery may not be possible in certain patients for a variety of reasons; in these cases, it is recommended that both the affected child and the parents receive counseling.
CASE
During a Combined Joint Task Force-Horn of Africa (CJTF-HOA) medical civic action program (MEDCAP) in the Harar region of Ethiopia, a 10-year-old African male accompanied by his father presented among 750 others for care during the first day of a 2-day humanitarian mission at the local school house. The patient's father related how his son was extremely self-conscious about having an extra finger on each hand and described how he was teased and shunned by his schoolmates. The father added that the local tribe believed the boy was cursed and requested help in getting the extra digits removed.
On examination, the patient was very withdrawn and shy. The father coaxed his son to display his hands. On examination, the patient had bilateral, asymmetric, postaxial polydactyly on both hands (type IIA on the right and type IIB on the left) (Figure 1). Both extra digits were sensate with well-formed nails, but neither finger was functional. The right supernumerary digit was swollen and inflamed with a serosanguinous discharge at the base of the pedicle caused by recurrent trauma and neurovascular compromise of the stalk. The patient's history and the remainder of the physical examination were unremarkable. No joint or bony structures were palpated in the pedicles, and both digits were thought to contain either small, disarticulated bone or cartilage. Since no radiology was available, the clinical diagnosis was made by inspection and palpation. Because of time constraints, the boy was scheduled for surgery early the following morning.
DISCUSSION
Polydactyly, derived from the Greek words poly for many and dactylos for digit, describes supernumerary digits on the hands or feet. Polydactyly is the most common congenital malformation in men, women, and cats. Although its exact incidence is unknown, the condition is estimated to occur in 1 of every 500 live human births. In Africa, incidence rates vary from 0.6% in Kenya1 to 2.3% in Nigeria.2 This cosmetic deformity is not well-accepted by many African tribes. In the United States, polydactyly is not considered a reportable congenital anomaly, and in Europe, it is not listed on any birth defect registries. In developing nations, there is a lack of accountability and consensus; most type I and type II polydactyly cases are treated with suture ligation in the nursery.3
Polydactyly can occur either with or without associated major birth defects, called syndromic or isolated polydactyly, respectively. Dozens of anomalies of syndromic polydactyly can be transmitted as autosomal recessive traits, including Down syndrome, trisomy 13 syndrome, Saldino-Noonan syndrome, Rubinstein-Taybi syndrome, and Ellis-van Creveld syndrome. Based on family history, isolated polydactyly is transmitted as an autosomal dominant trait with incomplete penetrance in 30% of cases.4 Polydactyly is mentioned in several popular books and is featured in paintings by Raphael, in which former Queen of England Anne Boleyn is wrongly accused of having the condition.
Classification systems Several systems are used to classify polydactyly based on radiologic, orthopedic, morphologic, genetic, or surgical treatments that range in number from 3 to 8 types per system. The Rayan-Frey system, modified in 2008,5 is used in this case report because it can be applied universally; is preferred by many hand, plastic, orthopedic, and reconstructive surgeons; and helps to plan treatment. The Rayan-Frey classifications for polydactyly are as follows: type I: small, soft-tissue nubbin with no bone or nail; type II: pedunculated, nonfunctioning digit attached to the hand by a narrow (less than 3 mm) pedicle (type IIA) or a wider pedicle (type IIB); type III: a well-formed, functioning digit that is either articulated with a bifid metacarpal head or a partially duplicated fifth metacarpal (type IIIA) or has its proximal phalanx fused to the fifth metacarpal (type IIIB); type IV: duplication with a separate sixth metacarpal; and type V: other cases, including polysyndactyly (in which there is syndactyly between the little finger and its duplicate) and triplication of the little finger.5