Having been there myself a few years ago, my heart goes out to anyone who finds him/herself in this situation. Hopefully, many of you already have a good Plan B. If you don't, it is time to give some serious thought to what your realistic goals, dedication to ortho, and honest expectations are.
The NRMP says that there were 589 pgy1 slots open this year. In the past few years there have been around 1200 applicants (I forget if this includes foreign applicants) each year. A lot of people who apply do not get in. Of these 600 or so people, some apply into multiple specialties and go into a different career path. Others decide from day 1 that they still want to go into ortho. I don't know the real numbers for these 2 groups but realize that there are a lot of people in this unmatched boat who are looking for Plan B. Decide what you want to do quickly but not hazardously, anf get ready to work your ass off regardless to give yourself the best chance the next time around. You have a few different options beyond scrambling for that one open spot:
Different specialty- if you are not committed to ortho or you honestly believe that you will never beef up you resume enough to get in seriously consider another specialty. Read the other multiple posts describing candidates with "poor" numbers who worked hard and got into a residency. If you put in enough hard work, you will be able to substantially improve your future application and will greatly improve your chance of matching. This being the case, be absolutely sure you want to go into another field before you make this decision.
Research- the main positives of this choice are that you remain closely involved with ortho, you may have very good opportunities to network with people in a given program, and you can add very tangible work (papers, book chapters, abstracts, talks, posters) to your resume. The negatives are that (depending on the position description) you may not be able to work with patients, you may not improve your chances with non-academic programs when you next apply, and you will unlikely get the most out of this opportunity if you hate research. I applied for ortho 2 years ago and did not match. I signed up for a 2-year ortho research fellowship, worked my tail off, put out a lot of literature, and networked with a lot of people. When I reapplied, I got 3 times as many interview invites as my first time and matched. Some possible programs that may have established research fellowships are Penn, Dartmouth, Columbia, BU, and Wake Forest (Penn has already filled their position). Call them up and find out if programs do exist. If you are able to get funding yourself, I am sure a far greater number of programs will be happy to accept a funded person into their lab for a year. Talk to the research faculty and lab director at your home program and the research dean at your medical school to get ideas and find out different options.
Prelim year- the positive of this option are that you remain involved in patient care and may be able to apply into a pgy2 position. These positions are few in number each year, however, and are supposedly not much easier to get into than the actual match. Negatives of this option are that you may end up doing an extra intern year, your schedule may make applying/interviewing tricky, and you are not working in a purely ortho environment. If you are certain that you don't want to go to an academic program, this option may be more beneficial to you than doing research. These positions are not hard to locate.
More med school- depending on your school, you may be able to take a 5th year. The positives are that you can do reseach and additional rotations. Your school may or may not charge you an extra year of tuition, and you may or may not be able to take out additional loans to cover your living expenses. This option may be safer than graduating into a prelim year or research fellowship but requires some good planning to make it work.
Regardless of what you do, keep a few things in mind. Whatever you do, perceptions of how hard you work will be a huge influence on their support for you in your next application. Do something you can really see yourself doing because if you don't it will be hard to truly throw yourself into it. Reassess your application plan when you reapply and be ready to apply to a lot of "safer" programs and 70+ programs across the board. Be completely honest with yourself and don't talk yourself into doing something that you really don't want to do. Remember, you were smart enough and worked hard enough to get into med school and make it through the past 4 years. That didn't change overnight, and you are still good enough to go where you want to go.
Best of luck to anyone in this situation. It may seem crappy now, but you will land on your feet, and things will work out.