hitchhiker thumb

hitch·hik·er thumb

malposition of the thumb, that as a result of shortness of the first metacarpal, stands at right angles to the radial border of the hand and in the same place as it; a characteristic sign of diastrophic dwarfism.

hitch·hik·er thumb

(hich'hī'kĕr thŭm)
Malposition of the thumb, which, as a result of shortness of the first metacarpal, stands at right angles to the radial border of the hand and in the same plane with it; a characteristic sign of diastrophic dwarfism.