Proximal placement of thumb

What it means

Proximal mislocalization of the thumb.

Thumb placement index greater than 0.55; or, the base of the thumb appears closer to the wrist than is typical. The technique for the thumb placement index is described in detail [Malina et al., 1973; Hall et al., 2007]. Briefly, the thumb placement index is the distance from the proximal crease of the index finger to the angle of the first interdigital space divided by the distance from the proximal crease of the index finger to the wrist flexion crease at the base of the thumb. This term should not be used with Preaxial polydactyly.

Rare diseases that can present with this24

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Low implantation of the thumb · Low-set thumb · Proximally placed thumbs