Polydactyly(redirected from Vestigial thumb)
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the presence of extra digits on the hand or foot. The most common congenital developmental anomaly, polydactyly includes such anomalies as doubling of the ungual phalanx or the presence of small digitiform cutaneous appendages. It occurs most commonly in the form of six digits, usually located on a single extremity; no more than 12 or 13 digits on one extremity have been observed. The extra digit is usually located on the inner or outer margin of the hand, and the majority of extra digits are underdeveloped. Polydactyly is corrected surgically.