Take everything that follows with a grain of salt as most of this is second-hand (and some of the hands were better than others)... BUT
There are about 550 (give or take) accredited positions available every year (I don't think this includes military numbers)
Approximately 1500 people (I think this includes US MS grads and IMG's) apply every year to at least one orthopaedic residency program.
About 750 people each year are selected for multiple interviews around the country (translated by me as they're good enough on paper to get more than their home program and the places they've done AI's)
About 85% of people who apply to orthopaedics match (not necessarily at an ortho residency... some of these are prelims and some of these are other specialties)
If you just run the numbers, that would mean about 33% of all people who've applied to at least one ortho program match in ortho... and about 80% of people that have multiple ortho interviews match in ortho.
Like I said eariler, these numbers come from casual conversations with various program directors and other staff that I have met. I have no "hard data" to support them. If any one else has heard something different, please correct me.