I am sure it depends on the program, but when I look at applications, I would much rather see a letter from a OB/GYN attending that is truly enthusiastic and genuine than a canned ortho letter. Maybe it is because I had one ortho, one gen surg, and on peds letter. All were outstanding letters. I had positive feedback regarding these letters during my interviews and ended up matchign at my top choice.
Like I said, every program is different, but in general, I think a very strong letter from a non-ortho staff is better than an average letter from a pod that obviously doens't know you that well.