I can speak a little for Mayo based on what I know from there. I think they interview around 60 or so people, in addition to all of their rotators. When I was there as a student I thought the volume was great and wasn't a lot of complex revisions etc. I saw a lot of primary joints done while I was there, in fact almost all of the joints I saw were primary ones. The residents operated depending how comfortable the consultants were with the residents. I saw a fellow and a PGY2 start and expose a spine with the PGY2 being guided by the fellow. The consutant came in once exposure was obtained, and everyone placed pedicle screws etc. I saw a PGY5 and a PGY3 pretty much do many of the total joints with the consultant assisting and directing.
As for trauma, probably a weakness perse but really you get plenty of long bone fractures, ankle fractures, etc and will be well equipped to deal with this. Dedicated trauma is during PGY3 and PGY5. Saw a lot of open tibias when I was there. Only one mandatory research project during your residency. A lot of their core didactics is during PGY2 and protected time, so that after noon everyday is protected for a semester, all the residents I spoke to had nothing but positive things to say about it.
Hope that helps a little bit.
