Most programs ask for three LoRs. Unless there are really unusual circumstances, one of these has to come from the chair of your home school's ortho department. For the other two, would a program where you rotated at prefer to see two letters from their own faculty, or one from their own faculty and one from a respected faculty member at another institution? I ask because I'm currently doing an away where I could probably ask for two letters, but I wasn't sure what the general rule was about that.
If you think it is better to have only one letter from the program being sent, is it better not to ask for two letters from the away elective? Could one of the letter-writers be offended if he/she were to go through the trouble of writing you a letter, only to see that you didnt even use it at all in your application?
Thanks to everyone for the advice.