either one of those would be ok. I took a nuc med rotation my fourth year and found it pretty cool. Mostly i took it b/c i wanted to know more about how to read bone scans, but they have some pretty cool other things going on, like realtime perfusion studies of the heart, 3 dimensional metabolic scanning for mets in cancer, and other things that are cool if you are a technology geek (like me) Now i will never use the cancer or heart stuff, but it was pretty cool and i will never get a chance to see stuff like that again. You have the rest of your life to do ortho...

Agree with comments from bonedoc. Especially now that ortho has its own internship and thus decreased exposure to other areas of medicine, I think you are better off doing something that may even be totally unrelated to ortho. You'll have the rest of your career to learn how to be a good orthopod but only a few more months to learn how to become a good physician.