Multilang Keyword Url

Hi there, nice to be a part of this community, lattelly i receive a project in codeignitor, and all of this is quite new to me, im still learning the concepts of MVC but unfortannly i need to resolve a issue that is quite of urgent but i cant quite get this to work, probably because im not doing to right way, so here it goes.

I have a website in multilanguage, and the strucutre of the url is like:

http://domain.com/properties/...

Basilly what i need is the keyword "properties" be changed when i switch to another language, the site content already makes this but is missing the keyword. I been looking about routes and here is the structure of my route:

$route['(:any)/properties/(:any)'] = "(:any)/show/detail/$2";

And im trying to make this

$route['(:any)/lang_key('property_lang')/(:any)'] = "(:any)/show/detail/$2";

But i guess im not doing the right way, could someone tell me how should i do it?

Regards