What it looks like
Webbed or fused fingers — medically called syndactyly — occur when two or more fingers are connected by skin or soft tissue rather than being fully separated. The webbing can be partial (connecting only the base of the fingers) or complete (extending to the fingertips). In Poland anomaly, the middle three fingers (index, middle, and ring) are most commonly involved, and the fusion is typically on only one hand.
A related condition, symbrachydactyly, involves fingers that are short, underdeveloped, or partially absent — sometimes with nubbins or soft tissue connecting small finger remnants. Symbrachydactyly and syndactyly can occur together in Poland anomaly, and the hand presentation can range from mild (slightly short fingers with minimal webbing) to more significant (markedly short or partially absent middle fingers).
Why it happens in Poland anomaly
Hand and finger differences in Poland anomaly result from the same vascular disruption that causes the missing chest muscle. The subclavian and axillary arteries also supply the developing hand and forearm on that side. When blood flow is disrupted around gestational week 6, the hand and finger development on the affected side may also be impaired.
Importantly, not everyone with Poland anomaly has hand involvement. Hand differences occur in roughly 50% of Poland anomaly cases. When they do occur, they are always on the same side as the chest involvement — never on the opposite side.
Other conditions that can cause webbed fingers
- Isolated syndactyly — Webbed fingers can occur as a standalone condition unrelated to Poland anomaly, sometimes genetic and sometimes sporadic.
- Apert syndrome — A genetic condition involving craniosynostosis and fusion of multiple fingers and toes on both hands, typically more severe and bilateral.
- Holt-Oram syndrome — Involves upper limb and heart abnormalities. A geneticist can distinguish this from Poland anomaly.
- Amniotic band syndrome — Bands of tissue in the womb can constrict developing fingers, causing fusion or amputation. The pattern is usually irregular and random rather than the characteristic middle-three-finger involvement of Poland anomaly.
When webbed fingers occur on only one hand and the child also has chest asymmetry on the same side, Poland anomaly is the most likely explanation and should be evaluated promptly.
Does it need surgery?
Surgical separation of webbed fingers is often recommended — particularly when fingers of different lengths are fused together, because unequal growth over time can cause the longer finger to bend toward the shorter one, creating a deformity. The timing and approach depend on the specific fingers involved and the anatomy of the fusion.
Pediatric hand surgeons who work with Poland anomaly patients are experienced with this surgery and typically perform it in early childhood. The goal is to improve hand function, appearance, and finger independence. Most children do very well after surgical separation.
When to see a doctor — and which specialist
If your child has webbed or fused fingers on one hand, especially combined with any chest asymmetry on the same side, seek an evaluation with a pediatric hand surgeon or pediatric plastic surgeon. Many children's hospitals have congenital hand difference programs specifically designed for this.
A pediatric geneticist may also be part of the workup to rule out underlying syndromes and discuss recurrence risk.
Find experienced providers in our specialist directory.