Prevent something from happening again.
If you can really prevent it from ever happening again – you’ve actually eradicated it.
In that case it there is no need to prevent it.
You only actually prevent it till the next time it happens.
So prevention never really works.
That being said, if a pirate does enter a hospital missing a leg, under no circumstances should he be given a wooden peg leg, because that just enables him to get back on his feet. He'll be raping and pillaging in no time.