Every article has a dynamic search topic link in What's Related, so i
hacked every mention of "/search.php?mode=search&type=stories&topic=topicname"
into
/searchtopic/search/stories/topicname/
Then created a new folder called searchtopic and then created a .htaccess document in this new folder.
the Mod_Rewrite rules in this doc are:
RewriteBase /searchtopic/
RewriteEngine on
RewriteRule ^(.*)/(.*)/(.*)/$ /search.php?mode=$1&type=$2&topic=$3