Does this usage make sense? Will it cause any problems later?

function model($folder, $file)
{
    global $db;
    if (is_file(path . 'app/models/' . $folder . '/' . $file . '.php')) {
        require_once(path . 'app/models/' . $folder . '/' . $file . '.php');
        return new $file($db);
    }
}

echo model('admin', 'common')->get();