That would work for things like installing stents to clear blocked or damaged blood vessel perhaps, but repairing liver and other organ damage would probably require actual (for example) liver cells - you can just patch a but of the liver with plastic and say "job well done" because that just won't work and may cause more harm than good.

But once the materials science catches up, could be that they could just build you a whole new artificial organ, and that without carving a big hole in you to install it.