Remove index from subpage path with mod_rewrite?

[Connie]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /index/$1 [L]

I tested that in the .htaccess but the links to subpages in the submenu were not modified, so calling these subpages the URLs still contained /index/ and by that I ran into an error