Your probability of matching based on 2011 Charting Outcomes is about 45% just based on step I. With your otherwise strong application I think you are looking at about 50%. Obviously consider that 2012 will have slightly different stats (it is getting harder every year). So on one hand it will be harder than 50% to match in 2013. But you can improve your grades and do 3 "aways". And if you will be stellar on those aways that will bump your chances up a little bit.
So I think you are looking at 50/50 in 2013.
So don't panic, just do it.
Pick any place that interviews all the rotators.
You have no luxury to waise months on places that won't even interview you.
And yes a strong letter ("the best student I ever worked with") from a well known orthopod (world known) will make your chance of matching skyrocket.
So I would go to one super star (HSS, etc) program and be the best rotator ever.
And also I would go to two "lower tier" programs that will interview you for sure.
Looking into the future, if everything works out, you have like 75% chance of matching. If not (you will mess up on a rotation or won't improve your grades), you still have about 50%. I actually think you have less than 50% of you won't improve. If you won't improve, then you will demonstrate a trend of "poorer quality" applicant and that may drop your chances to like 25%.
So you can become a 75% chance applicant or you may become a 25% chance applicant, or you may stay around 50%.
So work hard, be nice, study; don't sleep, eat, or urinate; be there at 5 am, leave at 11 pm, stay on call every other night during all your 4 rotations (1 home, 3 aways). And you will make it.
Or just go into radiology. Cush lifestyle. They have a bunch of open spots year after year.
But since you are here. Chances are you will be gunning for Ortho. So good luck.
P.S. I am not an expert. I just matched.