How to leaves old link - routing?

[eluser]devastator[/eluser]
Hello, i'm new here and for first time i will use codeigniter because he is very easy to use and have SUPRB user guide. Now my problem i have my old site he have very very good positions in google for long keywords and url are article.php?id=article_id i want to leaves them that only this url for articles all other to be dada/dada/213 how to make that? I put this routing

Code:

$route['article.php?id=(:num)'] = "article/index/$1";

but still not work i have 404 page error and I have article controller and index method with param $id