using REGEX to avoid preg_replace of links

hi, the following code replaces all keywords with a linked keyword. However, I would like to use REGEX in order to avoid the manipulation of keywords when they fall within links.

ex: if the keyword is orange

<br>orange</br> would become

<br><a href = “somelink”>orange</a></br>

however I’d like to avoid the following

original string:
<a href = “http://somedomain.com/orange”>yadayada</a>

string after preg_replace:
<a href = “http://somedomain.com/<a href = “somelink”>orange</a>”>yadayada</a>

code:

[code]
global $mainframe;

$content = $article -> text;
$current = JURI::current();

$keywords = $this -> params->def(‘keywords’);
$words = explode(“,”, $keywords);

$keywordLinks = $this -> params->def(‘links’);
$Links = explode(“,”, $keywordLinks);

$number = count($words);

for($i = 0; $i < $number; $i++)
{
$Links[$i] = ‘<a href = “../plugins/content/keyword.php?destination=’.urlencode($Links[$i]).’&location=’.urlencode($current).’&keyword=’.$words[$i].'”>’.$words[$i].'</a>’;

}

for($i = 0; $i < $number; $i++)
{
$words[$i] = ‘/b’.$words[$i].’b/’;
/*$words[$i] = str_replace(‘ ‘, ”, $words[$i]);*/
}

$content = preg_replace($words, $Links, $content);

$article -> text = $content;
[/code]

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