When I consider all of the different patients with a birth anomalies that I have the privilege to evaluate and treat, there is no question that symbrachydactyly is the diagnosis most often misnamed or unnamed. Amniotic constriction band is perhaps most commonly given as the incorrect diagnosis for the patients.
Symbrachydactyly literally means short, webbed fingers. And that certainly can be how patients with symbrachydactyly present as I have previously shared here- Previous Post. While there are 7 types (depending on your favorite classification), in my mind there are two types which are most common. All seven seem to be related to the same issue, and not a genetic one. We believe that a lack of blood supply to the developing limb is most likely the cause of symbrachydactyly and the timing determines the severity, the type.
The short finger type of symbrachydactyly is really the type that best fits with the name. The fingers are shortened due to a short or absent middle phalanx and the fingers are also commonly webbed. The other common type is the "cleft" type symbrachydactyly in which the thumb and little finger are normal or close to normal and the index, middle, and ring fingers are notably short and may be only a nubbin.
Here are two great examples of these two types of symbrachydactyly. First, the short finger type. This patient had surgery to separate the fingers at about 18 months of age and is functioning at a high level and is satisfied with appearance.
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| Short finger symbrachydactyly. Note the middle phalanx is abnormal. |
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| Short finger symbrachydactyly. Close examination shows the surgical scars from web deepening. |
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| Short finger symbrachydactyly. |
The other common type of symbrachydactyly is the cleft type. The painted fingernails help visualization. And the nubbins are small bones (distal phalanx) with nails that develop from the ectoderm after the vascular insult affects the mesoderm in the developing arm.
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| Cleft type symbrachydactyly. Note the three nubbins in the cleft. |
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| Cleft type symbrachydactyly. Note the thumb is normal and the little finger is more, but not normally developed as the middle phalanx is absent. |
Thanks for reading,
