What is Polydactyly?

Polydactyly is a hand or foot condition where there are more than ten fingers or toes present. Although not indicative of the presence of other genetic conditions, polydactyly usually presents as extra fingers or toes that sometimes alter the function of the hand or foot. Most cases, in fact, do not occur based on family history or genetics. Sometimes, the additional digit may get in the way of normal function in addition to the obvious cosmetic difference.

child grabbing parent's finger

Polydactyly: Characteristics and Common Issues with Extra Digits

Extra fingers or toes can occur adjacent to any digit but seem to occur more routinely with border digits (eg, the small finger or thumb).

Several characteristic problems are present:

  • The extra digit can split at the level of one of the bones
  • The duplication can involve the joint
  • The curvature of the remaining digit can occur
  • The duplicated digits are themselves underdeveloped

Surgical Treatment and Long-Term Management

Treatment is usually surgical. The extra finger or toe will need to be removed all the way to the level of the split, whether bone or joint. Once the digit is removed, the residual finger or toe will likely need to be straightened. Ligaments around duplicated joints are tightened, and bone is straightened as necessary for the final result. Surgical treatment is advocated as early as 6 months of age in some cases. Early correction can have long-term functional benefits.

Occasionally, a residual curvature deformity may persist or develop over the next several years. Secondary surgery may be required to correct this problem, should it develop.

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Types of Polydactyly

Polydactyly is categorized into various types based on the location of the extra digit, including preaxial polydactyly, postaxial polydactyly, ulnar polydactyly, radial polydactyly, tibial polydactyly, fibular polydactyly, and central polydactyly.

Preaxial or supernumerary polydactyly is a common type where an extra finger or toe is located at the base of the thumb or hallux, respectively. Radial or ulnar polydactylism occurs when there are extra fingers located near the radius or ulna bone, respectively. Postaxial or central polydactylism happens when an extra finger or toe is located near one of the smaller digits on either side of the hand and/or foot. Lastly, tibial and fibular polydactylism involve extra fingers located near lower leg bones called the tibia and fibula, respectively.

The cause for this condition could be genetic syndrome commonly seen in some families and isolated cases due to chromosomal abnormalities that occurred during development in utero. In some cases, medical intervention may be required depending on severity, but a surgical procedure is usually recommended if there are functional difficulties caused by an ectopic digit. During surgery, proper blood supply and adequate blood flow to residual digits should be maintained to ensure successful outcomes with minimal complications afterward. Occupational therapy will also help improve function following surgery if needed.

Causes of Polydactyly

It is estimated that up to 1 in 500 newborns have this condition. The cause of polydactyly is usually genetic, and it can be inherited as an autosomal dominant trait. Although most cases are isolated and do not present any associated birth defects, some forms of polydactyly may be related to chromosomal abnormalities such as trisomy 13. To determine the cause and type of polydactyly, physical examination and medical history should be taken along with genetic counseling for families with a family history of the disorder.

The form of polydactyly varies depending on where the additional finger appears on the hand: preaxial (on the thumb side), postaxial (on the small finger side), radial (next to the thumb), ulnar (next to pinkie) or tibial/fibular (near lower leg bones). In addition to a physical examination, imaging studies such as radiographs may help evaluate the structure and position of the additional digit as well as its blood vessel supply. Reconstructive surgery is typically recommended for symptomatic polydactyly to improve the function of adjacent fingers, reduce deformity, and achieve a cosmetically satisfactory result.

Surgery may also prevent long-term complications such as ulnar drift caused by imbalances in muscle forces from asymmetric muscles around duplicated joints. The goal of reconstructive surgery is to preserve sensation while preserving adequate blood flow for the long-term viability of residual digits after removing superfluous digits. For surgeons to achieve successful outcomes with minimal risks involved, proper technique must be used during surgery, such as being mindful of preserving proper nerve function and blood supply while resecting additional fingers appropriately.

Diagnosis and Tests

The diagnosis of polydactyly is usually made on physical examination. During the physical exam, your surgeon will examine the affected area and look for any additional digits or deformed digits. Your surgeon may also order imaging studies such as X-rays to assess the position, size, and structure of the extra digit. In some cases, genetic testing may also be ordered to determine if there is an underlying genetic cause for the condition. It is important to note that not all cases of polydactyly are associated with a genetic disorder; in some cases, it may simply be a spontaneous mutation or due to environmental exposures during prenatal development.

Your surgeon may also assess your range of motion (ROM) to evaluate how much movement you have in your extra digit(s). ROM assessment helps in surgical planning since certain procedures require more flexibility than others. Additionally, electrophysiological tests such as nerve conduction velocity (NCV) can help detect any nerve damage from compression due to an ectopic digit. NCV testing may be performed pre-operatively so that your surgeon can plan accordingly before operating on the affected area.

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Treatment Options for Polydactyly

In more severe cases, surgery may be necessary to improve function and aesthetics. Reconstructive surgery typically begins with a thorough evaluation, including physical examination, medical history, and imaging such as radiographs to determine the form and position of the additional digit. Surgery is then planned to preserve blood supply and minimize deformity while removing superfluous digits appropriately.

Surgeons may remove some of the soft tissue around the extra digit before resection in order to provide better exposure for surgical removal and reduce potential complications from bleeding vessels located within soft tissue. The surrounding skin can then be closed over the remaining bones either directly or using skin flaps based on surgeon preference. Wound care following surgery should include keeping gauze moistened with wound cleanser until redness has subsided, along with antibiotics if prescribed by your surgeon for infection prophylaxis.

In addition to reconstructive surgery, occupational therapy is suggested for those who experience functional difficulties post-surgery due to imbalanced muscle forces from asymmetric joints or lack of sensation from removed nerves. Occupational therapists (OTs) will assess the strength and mobility of the affected area while evaluating any difficulty with daily activities such as writing, typing, brushing teeth, etc., before developing a personalized therapy plan that is tailored towards improving the patient’s quality of life following reconstruction surgery. OTs also help patients adopt strategies for adapting activities so they can safely participate in daily life without fear of re-injury or further complications from an ectopic digit.

Complications and Risks Associated with Surgery

The most common complication from polydactyly surgery is wound infection due to poor surgical technique or inadequate postoperative care. Therefore, the surgeon practicing this type of surgery must have a high level of skill to properly resect the extra digit and preserve healthy tissue while also minimizing any potential damage to nerves and blood vessels that could lead to infection or other unwanted effects. Furthermore, proper pre-operative testing should be done to evaluate the patient’s medical history, physical examination results, imaging studies such as radiographs, and blood work results before any surgical intervention to safely assess any potential risks or complications during or after surgery.

In addition to wound infection, nerve injury is another possible complication that can occur with polydactyly surgery if proper technique is not utilized during the procedure. The surgeon must take special care when resecting the extra digit in order not to damage surrounding nerves, which are crucial for the sensation of residual digits following the removal of the ectopic digit. If these nerves are injured during the operation, it may result in decreased function of adjacent fingers causing patients discomfort or permanent loss of motor control leading to long-term complications such as joint instability due to imbalances in muscle forces around duplicated joints. As a result, it is important for surgeons performing this type of procedure to have a high level of knowledge and experience with similar cases for them to successfully remove extra digits without compromising safety or impairing function

Why Choose Dr. Panossian?

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"Dr. Andre Panossian is an amazing physician. He is a very kind natured person. He possesses sincerity for all of his patients and their families. Dr. Panossian makes you feel at ease and gives you hope for a better brighter future.The passion and dedication he has for his patients far surpasses my expectations."

- S.P.

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