Many parents experience a mix of emotions after the birth of their child.
As soon as the nurse brings the baby to their side, they notice, “Oh no, there’s an extra finger!” But neither the mother nor the father smokes or drinks, they have no other bad habits, and their own fingers are normal. So, why did they have a child with polydactyly? They just can’t figure it out.
In fact, this situation is not uncommon. In China, this type of deformity ranks in the top five of birth defects, the incidence of polydactyly is about 1%, accounting for 39.9% of congenital upper limb deformities; it is more common in males than in females, with a male to female ratio of about 3:2, the right hand is more likely to have polydactyly than the left, with a ratio of 2:1, about 10% of cases involve both hands, among which, the incidence of polydactyly of the thumb is the highest, accounting for more than 90% of all cases [1].
Below, I will provide a detailed introduction to polydactyly (polydactyly of the feet).
Polydactyly, also known as duplicated digits, refers to the presence of extra phalanges, soft tissue components, or metacarpals in addition to the normal fingers (toes), a common congenital deformity of the hand (foot). Children with polydactyly (polydactyly of the feet) may have 11 or even 12 or more fingers or toes.
These supernumerary digits may range in form and structure from a soft tissue without bone, a small tag, to a digit that is close to normal in appearance or function,
with nails, bones, joints, tendons, and neurovascular structures.
Figure 1: Common Polydactyly
The phenomenon of polydactyly (polydactyly of the feet) has a long history, with records dating back 3000 years in biblical texts. It is the most common congenital hand deformity among Chinese people, and it is most often seen next to the thumb.
Polydactyly (polydactyly of the feet) is mainly divided into three types:
1. Radial Side (i.e., bifid thumb)
Figure: Radial Side (Bifid Thumb) – Preoperative and Postoperative Appearance
2. Duplication of the Middle or Ring Finger
Figure: Central Type – Duplication of the Index, Middle, or Ring Finger
3. Ulnar Side – Duplication of the Little Finger
Figure: Ulnar Side – Duplication of the Little Finger
There is also a very rare deformity called mirror hand, which is also a type of ulnar duplication deformity.
Figure: Hereditary Mirror Hand and Foot
The causes of congenital polydactyly (polydactyly of the feet) are complex, including genetic factors, abnormalities during embryonic development, environmental factors, and associations with chromosomal abnormalities or syndromes[2].
Why Does Polydactyly (Polydactyly of the Feet) Occur?
What Are the Effects on the Child? Does It Affect Intelligence?
Polydactyly usually affects the appearance of the hand, and the impact on hand function depends on the complexity of the deformity.
Complex forms of polydactyly (polydactyly of the feet) may limit the range of motion of the fingers; poor hand development, finger deformities, small finger size, and weakened strength, such as crab-like polydactyly, can affect hand function.
Simple forms of polydactyly, while not significantly affecting hand function, may affect aesthetics, thereby impacting the child’s psychological development.
After the age of 2, a child’s psyche gradually develops, and they may become aware of their abnormalities, leading to negative emotions such as inferiority, which is not conducive to the healthy psychological growth of the child.
What Should Be Done? When Can Surgery Be Performed? Is It Safe?
It is recommended that parents take their child for examination and assessment as soon as possible after discovering polydactyly (polydactyly of the feet).
The purpose of the doctor’s early examination is not to treat urgently, but to help parents address their concerns.
Parents are usually very worried about issues such as appearance, function, and the likelihood of similar deformities in siblings, and they may feel guilty.
At present, individualized surgical treatment strategies have become an important direction for the management of polydactyly (polydactyly of the feet)[5].
The choice of surgical method and timing depends not only on the type and severity of the deformity but also on the risks of anesthesia, as well as various factors such as the patient’s age, functional needs, and psychological state.
1. Type of Polydactyly
Children with simple polydactyly (polydactyly of the feet) that are only connected by soft tissue can have surgery earlier, such as around 6 months old.
Children with complex polydactyly (polydactyly of the feet) involving bones, joints, or tendons will need to wait longer, such as after 1 year old, to allow for more precise handling of hand structure, but surgery should be completed before school age to avoid adverse psychological effects.
2. Anesthesia Risk
The safety of anesthesia significantly improves in children over 6 months old. Currently, there are no international reports of anesthesia having adverse effects on postoperative children.
Therefore, the timing of surgery is generally recommended to be between 6 months and 1 year of age, as the safety of anesthesia is higher at this time, and the hand structure is clear enough for surgical manipulation. At this age, the child has not yet developed fixed deformities or functional compensation, and postoperative recovery and functional reconstruction are better.
Will It Recur After Surgery? Will There Be Scars? Is It Hereditary?
Some families with polydactyly (polydactyly of the feet) may not opt for removal due to personal reasons, cultural customs, or religious beliefs, but to improve the child’s quality of life and functional recovery, we still recommend active surgical treatment.
1. Will It Recur After Surgery?
The treatment plan and prognosis for each deformity vary. Most children have good function after surgery, but complex cases may have weakened grip strength or limited mobility.
Additionally, postoperative care should be taken to prevent issues such as scar hyperplasia, residual deviation, or nail deformities, and some children may require a second correction.
To avoid complications such as joint instability, tendon adhesion, or vascular impairment, it is necessary to have experienced pediatric orthopedic or hand surgeons perform the surgery.
After surgery, children will also need regular follow-ups to monitor the recovery of hand/foot function and growth and development.
2. Will Surgery Leave Scars?
Surgical trauma will inevitably leave scars, which is an unavoidable natural law, but scar formation is directly proportional to age, the younger the age, the smaller the scar.
Preoperative strict disinfection, intraoperative attention to asepsis, meticulous aesthetic suturing, and postoperative wound care to prevent infection can all effectively reduce scarring.
In the early stages of scarring, compression bandaging, use of scar-reducing materials, and laser therapy can also help to fade scars.
Figure: Postoperative scars, although it is difficult to defy the natural law, proper scar management can effectively reduce scarring
3. Is It Hereditary?
It has been confirmed that about 100 genes are related to the occurrence of human polydactyly [6]. If there is no clear family history of heredity, the risk of recurrence is relatively low; if both parents carry dominant pathogenic genes, the risk of offspring suffering from the disease can reach 50%.
It is recommended that both spouses undergo genetic testing for a comprehensive assessment of heritability.
Finally, we hope that parents of children with polydactyly (polydactyly of the feet) do not panic. Seek medical attention in time upon discovering the issue, actively intervene surgically, and if you have any other questions, please leave a comment below～
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