Radial polydactyly varies from a barely visible radial skin tag to complete duplication. The clinical features of radial polydactyly will depend upon the extent of duplication. The incidence of radial polydactyly is reported as 1 in every 3,000 live births. It is most frequent in Indian populations and it is the second most common congenital hand disorder. Radial polydactyly refers to the presence of an extra digit (or extra digits) on the radial side of the hand. This is a less common situation, in which the affectation is on the side of the hand towards the thumb. In patients with African ancestry ulnar polydactyly mostly occurs isolated, whereas the presentation in Caucasians is often associated with a syndrome, though in a retrospective review, only 4 of 37 cases of ulnar polydactyly in Caucasians were syndromic. Ulnar polydactyly is also often part of a syndrome. The incidence in Caucasians is reported as 1 in 1,339 live births, compared with 1 in 143 live births in Africans and African Americans. Ulnar polydactyly occurs ten times more often in African populations. A triplication of the little finger is very rare. In case of a fully developed extra finger, the duplication usually presents itself at the level of the metacarpophalangeal joint. Mostly one neurovascular bundle can be identified, with no tendons present in the extra digit. Most commonly, the extra finger is rudimentary, consisting of an end phalanx with a nail, and connected to the hand with a small skin pedicle. It can manifest itself very subtly, for instance only as a nubbin on the ulnar side of the little finger, or very distinctly, as a fully developed finger. This can also be called postaxial polydactyly. This is the most common situation, in which the extra digit is on the ulnar side of the hand, thus the side of the little finger. In 2019 it was found that in cases of polydactyly with a fully functional additional digit, muscles to control the extra digit may be duplicated, resulting in increased motor control that allows the patient to carry out certain tasks with one hand that would normally require two. Polydactyly can be divided into three major types, which are discussed below, which depend on the location of the additional digit. The extra digit is most commonly an abnormal fork in an existing digit, or it may rarely originate at the wrist as a normal digit does. These are respectively known as postaxial (little finger), preaxial (thumb), and central (ring, middle, index fingers) polydactyly. The extra digit is most common on the ulnar (little finger) side of the hand, less common on the radial ( thumb) side, and very rarely within the middle three digits. Occasionally it contains bone without joints rarely it may be a complete functioning digit. The extra digit is usually a small piece of soft tissue that can be removed. In humans/animals this condition can present itself on one or both hands or feet. The supernumerary digit had normal sensation but no joint and hence could not move independently. Male with unilateral preaxial polydactyly affecting the left thumb. Īs of 2002, polydactyly has been associated with 39 genetic mutations. Īs of 2009, research has shown that the majority of congenital anomalies occur during the 4-week embryologic period of rapid limb development. Polydactyly belongs to the category of duplication. These categories are failure of formation of parts, failure of differentiation, duplication, overgrowth, undergrowth, congenital constriction band syndrome, and generalized skeletal abnormalities. In 1961, Frantz and O’Rahilly proposed, that congenital anomalies of the limb could be classified in seven categories, based on the embryonic failure causing the clinical presentation. Polydactyly is the opposite of oligodactyly (fewer fingers or toes).Īs of 1977, the incidence of congenital deformities in newborns was approximately 2%, and 10% of these deformities involve the upper extremity. Polydactyly or polydactylism (from Greek πολύς (polys) 'many', and δάκτυλος (daktylos) 'finger'), also known as hyperdactyly, is an anomaly in humans and animals resulting in supernumerary fingers and/or toes.
0 Comments
Leave a Reply. |