I cannot say that I know how difficult any program is to get into, but certainly University of Iowa Residents come from a variety of medical schools, not only "top" ones, as evidenced by the list of them on the department's web page.
It is an academic powerhouse, however. During my application process last year, I came to the conclusion that it was the best education available for someone intending an academic career. I think that places such as Mayo, Harvard, HSS, and a few others may have very similar reputations, but nowhere else did I find a faculty so dedicated to truly teaching the residents.
It seemed on this forum last year, HSS was the most popular. I have no doubt that it is a great program, but I think its overwhelming popularity in part stems from its location in a city that is apparently desirable to young singles.
Mayo also got a lot of attention, deservedly so. I think that what all of us find once we are in the mix of residency itself is that "even" a town such as Rochester, MN, or Iowa City, IA has more diversions than a resident's schedule will ever have time for.
At this point in the game, do not quibble over what programs will be however difficult to match with. None of us have any idea how these places choose interviewees and the subsequent match list. Just apply broadly to programs which sound like programs and places where you can live, work a lot, and learn orthopaedics. If you want to be an academic, then find programs that can support you in that goal through provision of mentors and research opportunities. If you want to avoid research, than pick more clinical or community-based programs. At this point, the application process really is that simple. The tough part comes when you have to choose which interviews to attend when a few overlap dates. The really tough part comes when, months from now, you have to place the programs in a ranked list. At least by that point you will have visited each of the places in question. . .