Short 1st metacarpal

What it means

A developmental defect characterized by reduced length of the first metacarpal (long bone) of the hand.

In contrast to the proximal phalanges of the digits 2-5, the proximal phalanx of the thumb is embryologically equivalent to the middle phalanges of the other digits, whereas the first metacarpal is embryologically of phalangeal origin and as such equivalent to the proximal phalanges of the other digits. {xref="https://orcid.org/0000-0002-0736-9199"}

Rare diseases that can present with this9

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: First metacarpal hypoplasia · First metacarpals hypoplastic · Hypoplastic 1st metacarpal · Short first metacarpal · Short first metacarpals