Conditions Causing Webbed Feet (Syndactyly)
Webbed feet (syndactyly) occurs either as an isolated congenital malformation inherited in autosomal dominant, autosomal recessive, or X-linked patterns, or as an acquired condition most notably in recessive dystrophic epidermolysis bullosa (RDEB) where progressive cutaneous scarring leads to pseudosyndactyly and mitten-like deformities of the feet. 1, 2, 3
Congenital (Inherited) Syndactyly
Genetic Patterns
- Non-syndromic syndactyly is most commonly inherited as an autosomal dominant trait, though more severe presentations may show autosomal recessive or X-linked recessive inheritance patterns 2, 3
- At least nine distinct types of non-syndromic syndactyly with additional subtypes have been characterized, exhibiting significant inter- and intra-familial clinical variability 3
- The phenotype depends not only on a main causative gene but also on genetic background and signaling pathways involved in limb formation, particularly the zone of polarizing activity and sonic hedgehog pathway 2
Syndromic Associations
- Syndactyly appears as a component of more than 300 syndromic anomalies, often associated with other musculoskeletal malformations or systemic syndromes 2, 3, 4
- When bilateral syndactyly is present, a genetic origin must be strongly considered 5
Acquired Syndactyly (Pseudosyndactyly)
Epidermolysis Bullosa (EB)
- RDEB generalized severe is characterized by progressive fusion of digits leading to pseudosyndactyly and mitten-like deformity of the hands and feet due to cutaneous scarring 1
- This complication occurs to a lesser degree and later in RDEB generalized intermediate 1
- Cutaneous scarring leads to joint contractures and deformities in the feet, resulting in reduced mobility and pain 1
- Ninety percent of patients with EB have one or more podiatric manifestations, though other EB subtypes (EBS, JEB, DDEB) do not typically cause mitten deformities or pseudosyndactyly 1
Clinical Impact
- The progressive fusion in RDEB significantly impacts quality of life by limiting footwear options, causing pain with ambulation, and reducing mobility 1, 6
- Contractures almost always recur after surgical intervention due to the progressive nature of the underlying condition 1
Clinical Presentation Patterns
Variability
- Syndactyly can be unilateral or bilateral, symmetrical or asymmetrical, even within the same individual 3
- The condition may involve simple webbing of soft tissue only or complex syndactyly with bony fusion 2, 4
Associated Conditions
- Foot malpositions may be associated with congenital hip abnormalities 7
- Malformations may occur alongside neurological and genetic abnormalities 7
Common Pitfalls
- Failing to evaluate for syndromic associations when syndactyly is identified, particularly when bilateral presentation suggests genetic etiology 5
- Overlooking the progressive nature of pseudosyndactyly in RDEB, which requires ongoing monitoring and may necessitate repeated interventions despite high recurrence rates 1
- Not recognizing that EB-related pseudosyndactyly is specific to dystrophic EB subtypes and does not occur in EB simplex, junctional EB, or dominant dystrophic EB 1