A servo-armature was a cybernetic device that was fitted onto the arms of some Borg drones. The servo-armature of a medical repair drone contained a laser scalpel, a biomolecular scanner, and a microsuture integrated into a single instrument.
In 2375, The Doctor was excited at the recovery of a functional medical servo-armature from the debris of a Borg probe destroyed by the USS Voyager. Upon seeing it, Tom Paris proclaimed that "no Federation sickbay should be without one." The crew, on the other hand, was less enthusiastic. (VOY: "Dark Frontier")