Cybernetics

Cybernetics are mechanical or electronic devices implanted in a human. Most cybernetics are intended to be permanent, and most mimic normal human function. Common cybernetic devices include arms and legs designed to restore lost limbs.

Such devices of varying complexity have been around for a long time, but they didn't become truly common until the early twenty-first century as high-tech replacements for soldiers who had lost limbs. The technology boomed in the first half of the 21st century, especially as new designs were created to enhance, rather than just replace, human function. World militaries were particularly keen on this application of cybernetics.

Despite rapid advances, some cybernetics never fully mimicked human function. Certain internal organs never matched the organic originals, and eyes and hands never did manage to meet human performance. Despite these obstacles, cybernetic technology continued to advanced and may have been able to completely mimic a human body by the end of the century.

Of course, the End stopped that. After the collapse of civilization, cybernetic devices are exceedingly difficult to find and install. It's not just the device itself that's needed, but trained technicians, surgeons, and special tools both for installation and for maintenance. The average person of No-Mans Land has to deal with missing limbs and other damaged body parts the old-fashioned way.