spondylolisthesis and spondylolysis. - dj

Could someone with a good dictionary please tell me if these words are spelled correctly? Mine is not very good and doesn't have both of these words in it (I do have a good med dictionary coming in the mail this week, thank goodness). I don't really trust all the sites when I google, plus I found a few different spellings, so I'm just not sure.

thanks so much!