Generally there are many factors. One is overall "feel" This includes your ability to fit in with the people you work with, your work ethic and your overall attitude. Being knowledgable about orthopedic things (appropriate to your level) is always good, but dont go out of your way to look good or make yourself look good at the expense of others, this is a sure way to NOT be liked. You will find that overall Ortho has a pretty laid back group of guys/gals that are easy to get along with if you do what is expected, show interest, and work hard. Good things to read are anatomy/surgical approaches and correlate this to clinical findings (dont just know where the radial nerve is, know when it is in danger and how to test for it, etc, etc). These are the things I was always told and now that i have seen rotating med students as a resident i still believe them.