Triphalangeal thumb – polysyndactyly syndrome

Triphalangeal thumb - polysyndactyly syndrome

Description, Causes and Risk Factors:

Syndactyly of several fingers or toes. There are several forms: a simple one and one with abnormal skull shape, Grieg cephalopolysyndactyly syndrome both inherited as an autosomal dominant trait; a recessive form is associated with cardiac defects. It has been described in some large pedigrees. Clinical presentation is variable within families, ranging from mild to severe. Malformations of the feet are usually less severe than those of the hands.

Triphalangeal thumb - polysyndactyly syndromeis caused by duplication encompassing the limb-specific regulatory element (ZRS) of sonic hedgehog (SHH). The Sonic hedgehog (SHH) protein produced in the zone of polarising activity (ZPA) is a major determinant of the identity and numbers of digits in early limb development. Preaxial polydactyly types II (PPD2) and III (PPD3) have been mapped to a critical region at 7q36, and subsequently shown to be caused by point mutations in the ZPA regulatory sequence (ZRS), a long range cis-regulator for the SHH gene. Triphalangeal thumb-polysyndactyly syndrome (TPTPS) and syndactyly type IV (SD4) were also mapped to the 7q36 region but pathogenic mutations in ZRS have not yet been affirmed.

This syndrome is transmitted in an autosomal dominant manner with complete penetrance and variable expression.

African Americans exhibit polysyndactyly more than any other race. The occurrence in most of these cases is not linked to genetic disease. The extra appendage is most often on the small digit side of the foot or hand.

Asian populations also exhibit polysyndactyly but tend to have the extra appendage present as a larger digit on the hand or foot. Within the Asian populations, this condition also accompanies other congenital abnormalities, such as fusion of skin between neighboring finger or toes or Down's syndrome


The list of signs and symptoms mentioned in various sources for triphalangeal thumb - polysyndactyly syndrome includes the 3 symptoms listed below:

    Extra thumb bone.

  • Webbed fingers.

  • Duplicated big toe.

Triphalangeal thumb - polysyndactyly syndrome symptoms usually refers to various symptoms known to a patient, but the phrase triphalangeal thumb - polysyndactyly syndrome signs may refer to those signs only noticeable by a doctor.


The medical information about signs and symptoms for triphalangeal thumb - polysyndactyly syndrome has been gathered from various sources, may not be fully accurate, and may not be the full list of triphalangeal thumb - polysyndactyly syndrome signs or triphalangeal thumb - polysyndactyly syndrome symptoms. Furthermore, signs and symptoms of triphalangeal thumb - polysyndactyly syndrome may vary on an individual basis for each patient. Only your PCP can provide adequate diagnosis of any signs or symptoms and whether they are indeed triphalangeal thumb - polysyndactyly syndrome symptoms.


The current mainstay for the treatment and management of triphalangeal thumb - polysyndactyly syndromeis operative. The indications in general for hand anomalies run true with syndactyly and include functional needs: The degree of function required by the patient; including whether delaying surgery may alter hand function and grip development. Aesthetic consideration: The appearance of the deformity and its subsequent effects on psychological and social aspects of the patient's life. It must be remembered that surgical intervention is not urgent. Despite this there are age related targets for reconstruction and dependency on the type of anomaly present.

Border digit syndactyly involving the thumb, index and ring fingers is felt to benefit from earlier release, usually between the ages of 6 to 12 months, and should always be released first in multiple digit involvement. The result in delayed surgery can involve deformity of the digit relating to forced flexion, angulation and/or rotation.

It is generally regarded that operative therapy should be done pre-school age. The main reason for this is that interaction with other children whilst having the anomaly is thought to have potentially detrimental affects on the child's social, functional and psychological development.

The main concern with surgical therapy is the fact that combined circumference of the two normal digits is approximately 1.4 times the circumference of the fused digits. Pre reconstruction it is felt that massaging the skin where the new web space will be constructed facilitates skin loosening and maximizes potential soft tissue needed during the procedure.

Full thickness skin grafts are used for soft-tissue coverage in the majority of cases at present, with altering levels of flap use. The choice of flap, and consequent extra need for full thickness graft coverage, appears to be dependant on the surgeon's preference, with multiple techniques and variances described in the literature. Several other methods have been used, including split thickness grafts and tissue expanders. Both have suffered with less favorable outcomes and increased complications compared to the use of full thickness grafts and have hence failed to establish themselves as alternative techniques. The use of no graft is more common, but this appears only to be of use in mild cases of simple syndactyly. Complications of all the surgical techniques include web creep, finger deviation (particularly in complex syndactyly) as well as those complications associated with any surgical procedure. The greater the degree of syndactyly, the more need there is for the surgeon to be aware of neurovascular variance and this takes on greater importance in graft and flap survival.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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