Patient Presentation
A 2-year-old male came to clinic for his health supervision visit. The parents and resident physician seeing the infant were worried about some webbing between his 3rd and 4th toes on his left foot. There were no other webbed digits and the patient seemed unbothered by the webbing.

The past medical history showed an uncomplicated prenatal and natal history. The webbing was not noted during his newborn hospitalization. The family history was negative for any congenital abnormalities or orthopaedic problems that the family was aware of.

The pertinent physical exam revealed a well-appearing male with growth parameters around the 50%. His left foot had minor webbing (estimated about 5 mm more than other digits) between the 3rd and 4th toes with spontaneous movement of each of the toes on the foot. The interdigital skin did not appear to have any hard spots when palpated, and had no inconsistencies when transilluminated in the office. The rest of his digits and examination were normal.

The diagnosis of of a simple syndactyly was made. The staff physician counseled the family regarding the problem and the family wanted to continue to monitor it. The patient’s clinical course over time showed no functional problems and he was walking unimpeded at his 12 month visit.

Discussion
Syndactyly is a very common congenital limb disorder. It derives from Greek from syn meaning together and dactylos meaning digit. It has an estimated incident of one in 2000 to 3000 life births, and represents approximately 20% of all hand malformations. Males are more affected than females, and it is more common in the Caucasian population. “The malformation is heterogeneous with unilateral, bilateral, symmetric, and asymmetric variants.” It is often found in isolation but can be syndromic with Apert’s and Poland syndrome being classic examples. Upper extremities are more commonly affected than lower extremities.

The hand digital web spaces most commonly affected in decreasing frequently are the third, fourth, second, and first.

Learning Point
Syndactyly is classified as simple if only the soft tissues are involved. Simple syndactyly is further characterized as incomplete if the soft tissue separation is proximal to the distal phalanx and complete if the soft tissue fusion continues all the way to the distal phalanx. (This makes sense as the embryological formation of the web space starts distally and migrates proximally). Syndactyly is considered complex if the adjacent bones are fused creating a synostosis. Complex syndactyly has abnormal positions of the bones and soft tissues which may include synostoses and webbing. Complex syndactyly is more common with congenital syndromes.

Syndactyly is usually noted at birth and the location and especially the extent of the webbing should be noted. If there is minor webbing (quite proximal) which does not appear to affect the digit function and it is obvious that there is no bony involvement, then patients are usually monitored but may be referred to surgery based on parent and provider preference. If the webbing is more extensive, appears to be affecting function or it is unclear if there is bony involvement then plain radiographs can help with evaluation and patients are often referred for surgical intervention.

Surgical treatment is reconstructive with the goal of allowing independent functioning of each digit. Syndactyly that requires surgical treatment is usually started between 12 and 18 months of age, which allows the hand to grow and to have fewer complications. Simple syndactyly surgical procedures may seem straightforward, but issues such as the changing configuration of the fingers along their length, and even that there is up to 30% less skin available on fused fingers makes the procedure more challenging.

Questions for Further Discussion
1. What are common foot problems? A review can be found here
2. How should shoes be properly fitted? A review can be found here
3. What is the difference between a malformation and deformation? A review can be found here

Related Cases

Disease: Syndactyly | Foot Injuries and Disorders | Hand Injuries and Disorders

Symptom/Presentation: Minor Congenital Anomaly

Specialty: Genetics | Orthopaedic Surgery and Sports Medicine | Surgery

Age: Infant

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Foot Injuries and Disorders and Hand Injuries and Disorders.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Tonkin MA. Failure of Differentiation Part I: Syndactyly. Hand Clinics. 2009;25(2):171-193. doi:10.1016/j.hcl.2008.12.004

Kvernmo HD, Haugstvedt JR. Treatment of congenital syndactyly of the fingers. Tidsskr Nor Laegeforen. 2013;133(15):1591-1595. doi:10.4045/tidsskr.13.0147

Chouairi F, Mercier MR, Persing JS, Gabrick KS, Clune J, Alperovich M. National Patterns in Surgical Management of Syndactyly: A Review of 956 Cases. Hand (NY). 2020;15(5):666-673. doi:10.1177/1558944719828003

McGarry K, Martin S, McBride M, Beswick W, Lewis H. The Operative Incidence of Syndactyly in Northern Ireland. A 10-Year Review. Ulster Med J. 2021;90(1):3-6.

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa