Some may not agree with me but again you are asking for opinion so here is my two cents:
Before I transferred medical schools, I was on the admissions committee at my former school and before that I was a volunteer interviewer, so I had the chance to interview somewhere around 100 candidates for medical school and that is where my perspective comes from:
You are a sophomore in undergrad. Certainly you should be honored to have the offer of an early interview to your home school. I'm sure that is a result of stellar grades in undergrad...keep it up. And it is great that you find you are interested in orthopedics. We all think pretty highly of it.
As for your interview, even more important than why BU, is why medical school in the first place? Most students have spent some of high school and then 3-4 years of undergrad, +/- other careers, post bacc. programs, etc. to think about and expose themselves to medicine. You do not have this luxury before your early interview, but you should be exposing yourself to as much medicine as you can now (your pre-med courses, +/- medical research, and certainly shadowing). If someone asks you what your typical day would be like in 15 years, you should know that it wont be "show up at 9am, see some patients, take 1hr lunch, see some more patients, be home by 5pm...etc." You should have a clue to some of the national issues that face healthcare in the coming years. You should KNOW WHAT YOU ARE GETTING INTO. I could go on and on, but my point is although it is exciting to think of your residency in orthopedic surgery, you should focus on the steps and hurdles right in front of your nose, i.e. 2 more years of undergrad and matriculation into medical school. While you are at it, you should get a decent idea of what BU has to offer before you interview....
While I think you shouldn't be asking this yet, I'll answer your original question anyway:
Doing well at whatever school you are attending will trump all. If you are stellar, people take notice. Sure it is true that people frequently match at their home program...they know you and you know them and it is a nice relationship. But take one look at any school's match list and you will see that people match in all specialties in all locations and orthopedics is no exception.
Regionalism is alive in the match process, sure, but if you read posts all over this site you will see things like "top tier school in southeast.....I matched at UCSF my #1" (and so forth). You get the idea. What they don't always point out is that the match is a very personal process. If you get into your early 4th year and decide to blow out of Boston, you can certainly do that.
Anyway, you should forget about where you want to match for residency in orthopedics and focus on doing well in undergrad first...
Don't sweat it. If I were you, I'd be at Fenway tomorrow for the ring ceremony/home opener, not worrying about matching for residency....
