Syndactyly of A.Griguolo

Generality

Syndactyly is a congenital malformation of the hands or feet, which is characterized by the fusion of one or more fingers.

More common than one might think, syndactyly can have various origins: it can be the result of unrecognizable causes, it can be a hereditary trait transmitted by parents or, finally, it can be a sign of some genetic syndrome.

Hands and feet are the hands that suffer most from the presence of syndactyly; in fact, in the feet the anomaly in question is generally without consequences (and is even rarer).

All of this explains why syndactyly in the hands always requires the use of surgery, while that at the feet only on some occasions.

The diagnosis of syndactyly is simple and is based on physical examination.

What is syndactyly?

Syndactyly is the congenital malformation characterized by the fusion of two or more fingers of the hand or foot.

In other words, doctors talk about syndactyly, when at least a couple of fingers and / or toes of an individual are fused together, instead of being normally separated.

In syndactyly, the anomalous fusion of the fingers may be limited to affecting the skin or may also involve the bones ; therefore, it is possible to be faced with cases of syndactyly, in which the fingers are joined only at the skin level, and cases of syndactyly, in which the fingers are joined at the skin level and at the bone level (there is a union between phalanges) .

Important : the congenital aspect of syndactyly implies that the latter is present from birth.

Epidemiology

Syndactyly is a more common anatomical anomaly than is thought; according to statistics, in fact, 1 newborn out of about 2, 500 would be affected.

Between hands and feet, syndactyly tends to affect the hands more frequently: numbers in the hand, 50% of syndactyly cases involve a hand.

For reasons that are still unknown, syndactyly is more common among Caucasian species than among African-American or Asian breeds.

Finally, for unknown reasons, syndactyly occurs more frequently in the male population than in the female population.

Origin of the name

The word "syndactyly" derives from the union of the Greek terms "sin" ("συν") and "daxtylos" ("δάκτυλος"): "sin" means the concept of "union" and can also be translated as "together", while "daxtylos" means "finger".

Thus, the literal meaning of "syndactyly" is "united finger" and has the intent to refer to the interdigital union (ie between the fingers), which characterizes the malformation in question.

Causes

Premise: as we will see later, syndactyly is a clinically relevant condition when it affects the hands (these are also the most affected sites). This explains why the information the reader is about to obtain specifically relates to the pathophysiology of syndactyly in the hand.

During the normal embryonic development of a fetus (therefore after conception), the entire upper human limb (including the hand) takes shape and assumes the appearance it will have in the post-natal life between the IV (fourth) and the VIII ( eighth) week of gestation . This means that, 56 days after conception, the human being already has his hands in their final form, separation between the fingers included (at the origins of its development, the upper limb remembers a paddle, with the hand that represents its 'end used to cut water).

In such a context, syndactyly is the consequence of an error during the development of the upper limbs, in the 56 days mentioned above. To be precise, the error in question is a cell signaling error, such that the appropriate separation of the fingers does not take place.

In other words, it is as if the biological signal indispensable to the division of the fingers - that at the origins are actually all united among them - came less or was not appropriate for the purpose.

Did you know that ...

The separation of fingers and toes is the result of a cellular signal that causes apoptosis . Apoptosis is the so-called programmed cell death, a completely physiological process, implemented by the body for precise purposes, including correct development of anatomical parts, survival, etc.

In apoptosis, we witness the death of "useless" cells, not essential to survival, sometimes even harmful.

Apoptosis is opposed to cellular necrosis, which is instead the death of a cell, resulting from pathological processes, sometimes even very serious.

Sporadic, hereditary and syndromic syndactyly

In most cases, syndactyly is the result of an isolated event, during embryonic development, which alters the final formation of the hand; for these syndactyly circumstances - identified with the term sporadic syndactyly - a precise cause is not recognizable, therefore neither genetic factors nor hereditary factors seem to have a role.

In the remaining clinical cases, syndactyly may correspond to:

An inherited anatomical anomaly (ie transmitted by one or both parents), not associated with other abnormalities or other symptoms ( hereditary syndactyly );

or to:

An anatomical anomaly inserted within a much broader clinical picture, the result of a genetic or presumed syndrome ( syndromic syndactyly ). Among the genetic or presumed syndromes associated with syndactyly are: Poland syndrome, Apert syndrome and Holt-Oram syndrome .

Genes implicated in syndactyly

Molecular biologists and genetics experts have identified at least 3 chromosomes that, if mutated in some specific portions, play a crucial role on the onset of syndactyly.

The 3 chromosomes in question are chromosome 2, chromosome 6 and chromosome 7 .

Chromosome 2 has a region that, if mutated, is responsible for syndactyly between the third and fourth finger of the hand or foot.
Chromosome 6 has an area that, if mutated, is associated with syndactyly of the little finger of the hand with the neighboring ring finger.
Chromosome 7 has an area which, if mutated, is related to the syndactyly of all the fingers of the hand or foot.

Symptoms and Complications

The fusion of the fingers that characterizes syndactyly is the clinical sign identified with the term " webbed fingers "; this term clearly refers to the similarity between a hand or foot affected by syndactyly and the foot of a palmiped.

The presence of syndactyly may disturb the functionality of the hands or feet ; to be more precise, it is easier to make the use of hands difficult, as these are fundamental organs in grasping or holding objects.

Clearly, syndactyly is all the more serious and disturbing to the bearer, the more fingers involved.

Syndactyly on the feet is rarely responsible for disorders that impair the patient's quality of life.

Types of syndactyly

According to a known classification of syndactyly that takes into account how the fingers are fused together, there is:

Incomplete syndactyly : it is when the union of two or more adjacent fingers is not total, that is it does not reach the ends.
Complete syndactyly : it is when the union of two or more fingers is total, that is, it reaches the ends.
The syndactyly simple : it is when the union between two or more fingers concerns only the soft tissues, therefore in fact only the skin.
Complex syndactyly : it is when the union between two or more fingers concerns the soft tissues, the bones and the cartilages.
Complicated syndactyly : it is when, in addition to the union between the fingers at the level of the skin, bones and cartilages, the presence of an extra finger or the absence of a finger are also added.

When should I go to the doctor?

Syndactyly is an anomaly that does not go unnoticed at the time of birth. Therefore, its identification and subsequent planning of the most appropriate treatment are immediate.

Complications

If left untreated, in addition to negatively affecting the functionality of the affected hands or feet, syndactyte alters normal finger growth, causing noticeable deformities .

A classic deformity resulting from syndactyly is the curvature of the longest finger in the direction of the shortest finger.

Diagnosis

A physical examination is sufficient to make the diagnosis of syndactyly. In medicine, the physical examination is the medical observation of the patient, aimed at detecting any pathological signs and to outline a picture of the symptoms present.

The physical examination allows to establish even if the syndactyly is incomplete or complete and if the number of fingers is normal or not.

What are the next steps?

Once the presence of syndactyly has been identified, the diagnostic doctor starts the investigations necessary to identify the causes triggering the anatomical anomaly present.

As a rule, these surveys consist of:

An accurate medical history . It is the critical study of the symptomatology through specific questions (NB: since the patient is usually a newborn, the doctor's interlocutors will be the parents), combined with an examination of the family history.
Through the history, the doctor understands whether syndactyly is a recurrent anomaly in the patient's family; this information is important to establish the nature of syndactyly, ie whether it is sporadic, hereditary or associated with a genetic syndrome.
An X-ray radiological examination . X-rays are needed by the doctor to determine if the fusion between the fingers also affects the bone tissues and cartilaginous tissues.
A genetic test . It is the DNA analysis aimed at detecting mutations of critical genes.
In a context of syndactyly, it is the investigation to establish whether the present anomaly is related to some genetic syndrome.

Therapy

The treatment of syndactyly is surgical .

Before analyzing the syndactyly surgery in detail, however, a clarification is necessary: when the anomaly is localized in the feet, it is generally superfluous to resort to surgery, except for the symptomatic cases and for those for which complications are expected; when the malformation lies in the hands, surgery is a must, to avoid complications and to give the hand a normal appearance.

The syndactyly operation: what does it consist of?

The surgical operation carried out in the presence of syndactyla includes:

The execution of a zig-zag incision where the skin unites in an anomalous way the fingers involved. The zigzag incision is the best way to avoid the use of skin grafts during the next phase.
If the fusion also involves the bone and cartilaginous tissues, the incision must obviously also involve these tissues;
The closure of skin flaps resulting from the incision through different stitches.
This part of the intervention allows the fingers to assume the normal appearance.

Some cases of syndactyly in the hands are such that, despite the zig-zag incision, a skin graft is still needed to facilitate closure.

POST-OPERATIVE PHASE

Immediately after the syndactyly surgery, the treating physician provides to apply a plaster on the anatomical portions concerned, in order to protect and ensure the correct healing of surgical wounds. Therefore, once the plaster has been eliminated (in general, this occurs after a few days), it temporarily applies splints to the worked fingers, awaiting complete recovery.

For obvious reasons, the complete recovery from a complex syndactyly intervention (ie in the presence of a fusion between bone and cartilaginous tissues) has longer times than the complete recovery from a simple syndactyly operation.

WHAT IS THE BEST MOMENT TO PERFORM THE INTERVENTION?

The surgical treatment of syndactyla must take place at an early age.

The best time to carry out the operation varies according to the site of the syndactyly:

If the fusion is between thumb and forefinger or between ring finger or little finger, the operation must be held within the sixth month of age .
If the fusion is between fingers other than those indicated above, the operation can take place even at 18-24 months of age .

IS A SINGLE SURGICAL INTERVENTION SUFFICIENT?

Some cases of syndactyly in the hand require a second surgical procedure to be performed at a more mature age. In these situations, the post-operative phase also includes a cycle of physiotherapy sessions.