Having the Athletic training background will help you with something to talk about during the interviews, it will not give you much of an "advantage" when it comes to getting interviews. Orthopedics is very competitive and getting more and more so by the year. You would first need to get into medical school and do well. Good boards, grades, ortho research, rock your 3rd year clinical rotations, and honor your ortho home + away rotation, get very solid letters of Recs from ORTHO attendings, and if you make AOA, it will open many doors for you. Then it comes down to the interviews, usually with any where between 4-10 attendings and residents depending on the program. The program is looking for the right fit which is what you are looking for as well. In order to get a spot, you need to convince your interviewers why you would be a better residents than the other outstanding canidates, why they should pick you.... basically, if you are interview for 3-4 spots, you need to be in the top 15 to have a good chance of matching. Each program will interview about 10 per spot with most programs getting >100 applications per spot. So to give you an example, my program received ~420-430 apps and interviewed 50 for 4 spots this year, and we ranked about half that number on the list. I have seen some very very good applicants that came through this year, and most of them were all very nice guys or girls.
Basically, work hard in everything you do in life and the above is a very simplified formula for you to get an spot in Orthopedics Surgery. The above things are much eaiser said than done, but missing one or the other will NOT prevent you from matching, b/c you need the complete package but not perfection. Although I did see a kid come through this year for our program that was pretty much perfection in terms of his acomplishments. Honored everything in yr 1-3 med school (top 20 school), AOA, was one of those scholars as an undergrad (Marshall or Fulbright?) that spent 1 yr over sea in ortho research with over 30 publications /abstracts/presentation, honored all ortho rotations, letters from his home program chair that said he was the best in last 10 years and another attending said he was the best in the last 30 yrs, oh,... did I mention this kid also has a mid 260's on Step I. Hmmm.... And he was a very nice guy, I did not think he was this qualified until I seen his app.