I cant seem to figure out the proper syntax for this line.

PHP Code:
<a href="read_post.php?tid=' . $threads['thread_id[1]'] . '&subject=' . $threads['subject[1]'] . '&name=' . $row10['name'] . ' 
Specifically, I am looking for the $threads['thread_id[1]'] part. The rest is working fine but for some reason this is not working. I have tried $threads[thread_id'[1]] but that gave me an error so I went with the code above and it did not give me an error but does not print the content in the variable. The array I am printing is a multiple line array taken from a mysql database. I know my query works as it has been tested.