Classification and external resources

New born baby hand showing complete complex syndactyly of two fingers.
ICD-10 Q70
ICD-9 755.1
OMIM 185900 186100 186200 186300
DiseasesDB 29330
MedlinePlus 003289
eMedicine orthoped/563
MeSH D013576

Syndactyly (from Greek συν- = "together" plus δακτυλος = "finger") is a condition where two or more digits are fused together. It occurs normally in some mammals, such as the siamang and kangaroo, but is an unusual condition in humans.



Syndactyly can be simple or complex.

  • In simple syndactyly, adjacent fingers or toes are joined by soft tissue.
  • In complex syndactyly, the bones of adjacent digits are fused. The kangaroo exhibits complex syndactyly.
Type 1 Syndactyly in adult female

Syndactyly can be complete or incomplete.

  • In complete syndactyly, the skin is joined all the way to the tip of the finger
  • In incomplete syndactyly, the skin is only joined part of the distance to the fingertip.

Complex syndactyly occurs as part of a syndrome (such as Apert syndrome) and typically involves more digits and with complex syndactyly.

The hand of a patient with Greig cephalopolysyndactyly with syndactyly of several digits.

Fenestrated syndactyly means the skin is joined for most of the digit but in a proximal area there is gap in the syndactyly with normal skin. This type of syndactyly is found in amniotic band syndrome.

Simple syndactyly can be full or partial, and is present at birth (congenital). In early human fetal development, webbing (syndactyly) of the toes and fingers is normal. At about 16 weeks of gestation, apoptosis takes place and an enzyme dissolves the tissue between the fingers and toes, and the webbing disappears. In some fetuses, this process does not occur completely between all fingers or toes and some residual webbing remains.


Five types[1] of syndactyly have been identified in humans. The corresponding loci associated with these types and their common phenotypical expression are as follows:

  • type I: 2q34-q36;[2] webbing occurs between middle and ring fingers and/or second and third toes.
  • type II: 2q31;[3] also involves long and ring fingers, but has a sixth finger merged in between.
  • type III: 6q21-q23; small finger is merged into the ring finger.
  • type IV: 7q36;[4] involves all fingers and/or toes
  • type V: 2q31-q32; similar to type I, but the metacarpals and metatarsals may also be fused.


4 year old boy's right hand, after surgery to rectify complete complex syndactyly of middle and ring finger. Bone had been joined at tips of fingers, together with fingernails, prior to corrective procedure. Surgery was conducted at 9 months of age. Note webbing "creep", and scar tissue, for which corrective surgery is due when boy is approximately 6 years of age.


Syndactyly of the border digits (thumb/ index finger or ring/ small fingers) is treated at early age to prevent the larger digit from curving towards the smaller digit with growth. Typically, syndactyly of these digits is treated at 6 months of age. The treatment of syndactyly of the other digits is elective and is more commonly performed when the digits have grown, at 18– 24 months of age.


Because the circumference of the conjoined fingers is smaller than the circumference of the 2 separated fingers, there is not enough skin to cover both digits once they are separated at the time of surgery. Therefore, the surgeon must bring new skin into the area at the time of surgery. This is most commonly done with a skin graft (from groin or anterior elbow). Skin can also be used from the back of the hand by mobilizing it (called a "graftless" syndactyly correction) which requires planning over a period of months prior to surgery.


The most common problem with syndactyly correction is creeping of the skin towards the fingertip over time. This is likely due to tension at the site of the repair between the digits. Additional surgery may be required to correct this. One critique of using skin grafts is that the grafts darken in the years after surgery and become more noticeable. Also, if the skin grafts are harvested from the groin area, the skin may grow hair. Finally, the fingers may deviate after surgery. This is most commonly seen in complex syndactyly (when there has been a bony joining of the fingers).

See also

  • Dactyly, the arrangement of fingers and toes in different kinds of animals


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Syndactyly — A condition in which two or more of the fingers or toes are joined together. This joining can involve the bones or just the skin between the digits. Joining of the bones is called bony syndactyly. Webbing of the skin between the fingers without… …   Medical dictionary

  • syndactyly — noun a) The normal condition, in some animals and birds, of having fused digits. Pranamya Menaria (India; born August 10, 2005) has 25 in total (12 fingers and 13 toes). This is as a result of the condition Polydactyly and Syndactyly. b) The… …   Wiktionary

  • syndactyly — noun Etymology: New Latin syndactylia, from syn + Greek daktylos finger Date: 1864 a union of two or more digits that is normal in some animals (as various marsupials) and occurs as a human hereditary disorder marked by webbing of two or more… …   New Collegiate Dictionary

  • syndactyly — syn·dac·ty·ly (sĭn dăkʹtə lē) or syn·dac·tyl·ism ( tə lĭz əm) n. Biology 1. The condition of having two or more fused digits, as occurs normally in certain mammals and birds. 2. A congenital anomaly in humans characterized by two or more fused… …   Universalium

  • syndactyly — n. state of having webbed fingers or toes, state of having digits that are partially joined together (of certain mammals or birds) …   English contemporary dictionary

  • syndactyly — syn·dac·ty·ly …   English syllables

  • syndactyly — n. congenital webbing of the fingers. Adjacent fingers are joined along part or all of their length. They may be joined only by skin, or the bones of the fingers may be joined. Treatment is surgical separation of the fingers, and skin grafts may… …   The new mediacal dictionary

  • syndactyly — noun birth defect in which there is partial or total webbing connecting two or more fingers or toes • Syn: ↑syndactylism • Topics: ↑homo, ↑man, ↑human being, ↑human • Hypernyms: ↑birth defect, ↑ …   Useful english dictionary

  • Syndactyly, partial — A condition in which fingers or toes are partially joined together. Syndactyly can involve the bones or just the skin. With partial syndactyly, the connection extends from the base only part way up the involved digits. Partial syndactyly is the… …   Medical dictionary

  • Syndactyly, complete — A condition in which fingers or toes are completely joined together, with the connection extending from the base to the tip of the involved digits. Complete syndactyly is the opposite of partial syndactyly, in which the connection extends only… …   Medical dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.