Use PHP to rewrite URLS?

Question

I want to make my own url rewriting rules using couple of PHP-MySQL. The concept is to have a rule in my .htaccess that send all request to my index.php file like :

RewriteRule ^([a-zA-Z0-9_-]+)/$     index.php
RewriteCond %{REQUEST_URI}  !\.(.+)$
RewriteRule ^(.*)([^/])$ http://%{HTTP_HOST}/$1$2/ [L,R=301].

And php will take all params via a super global var like $_SERVER['REQUEST_URI'] and explode("/", $_SERVER['REQUEST_URI']).

function rewrite(){
    $paramKeys = array("", "locale", "page", "par1", "par2", "par3", "par4", "par5");   
    $paramValues = explode("/", $_SERVER['REQUEST_URI']);   

    foreach($paramValues as $key => $value){
        if (!is_array($key)) {
            $paramValues[$key] = htmlspecialchars(stripslashes(trim($value)));  
            if($key == 0){ //but the 1st slash is in the end of URL
                continue;
            }
            elseif($key == sizeof($paramKeys)){
                break;
            }
            else $params[$paramKeys[$key]] = $value;
        }
        else continue;

    }
    return $params;
}

And compare the requested URL with URL's in my database to send http statut in order of the requested file is found 200, moved 301, or not found 404.

Have I a bad idea ? if not, how can I perfectionize it. Thank you !