In the metacarpal sign, a line drawn along the heads of the 4 and 5 metacarpals will intersect the head of the 3 metacarpal if shortening is present. The shortened 4 metacarpal is the key to the sign.
The sign is positive in up to 9.6% of normal individuals . It is however seen in a variety of conditions.
For a gamut of this sign see: short 4/5 metacarpal.