Definitely you need to know your CV cold. Any research you put on your CV, expect detailed questions. If someone can figure out that you didn't do much for that authorship, your research experience if not more will be eliminated from your accomplishments.
You WILL get asked some variations of "Why orthopaedics?" And you should have an answer. Hopefully it isn't something lame about tearing your ACL as a kid... you also ate pizza as a kid, but you don't want to run a pizza shop do you? Your whole decision about the career for your entire life hopefully isn't a cliche. But, speaking of sports, imagine what you'd think of a college football star who couldn't name his favorite player/team/coach/etc. These people know their field in and out, because it is your passion. So, what do you know about the history of orthopaedics? Where did it come from? Who are some important people? At least check out wikipedia, if not some book on it (Orthopaedics, an Iconography; Rearticulations of Orthopaedic Surgery; Menders of the Maimed, etc).
