Although high board scores are nice they don't guarantee you a spot. The things that will help you is to:
1. Rotate at the institution you really want to be at- It very difficult for someone to get a spot without the program knowing who you are.
2. Work your ass off, and love scut work- helping the residents out can go along way in terms of putting in a good word for you
3. Be a team player and get along with everyone
4. Have a basic level of ortho knowledge- When a residents asks you to read and X-ray (and they will) and you cannot give a description of the fx you are going to be hosed.
5. Act interested; no one likes to see you staring off into space or yawning when you claim that you are passionate about ortho
6. Even if you do all of these, you still might not get in. Its extremely competitive and some people who probably deserve to get in don't. Sorry, thats the cold hard facts though