I was just thinking about what a big deal the replicator technology in Star Trek would be for medical science
Well, first: they have amazing scanning technology and computing is minified to molecular or atomic levels, so each time you went for a check-up, the doctor could conduct a full-body scan; your entire medical history in a series of snapshots could be stored somewhere inside your body, maybe in the brain.
Then if something happened - anything from a missing limb to brain damage - the doctor could replicate what was missing and surgically attach it. Or, replicate it directly into your body.
Effectively git diff; git reset