I think there's 2 issues here:
1. Medical Licensing - anyone who has an equivalent degree and passes the 3 steps of the USMLE can get a medical license (with some exceptions for those of us in residency, but ultimately we too must pass step 3).
2. Board Certification - Normally only US or Canadian graduates of an Orthopaedic Surgery residency can sit for part 1 & 2 of the american boards. However with the distinguished scholar program, IMGs can sit as well. I have yet to see any proof, but i've heard from IMGs doing fellowships that instead of repeating their residency, if they complete fellowship after fellowship (avg. of 4-5, total), and when one of the institutions sponsors them, they can sit for the ortho boards as well. I guess this makes sense since it would be difficult for an IMG to practice in an academic setting in the US without being board certified in the first place, the only way to do it is through fellowships...
That being said I think the answer to the original question, is that you cannot practice orthopaedics in the US with JUST your medical license, no one would hire a non-board certified surgeon (not as staff, anyway). You can start your own practice, but i doubt many patients in the US would feel comfortable going to someone who is not board-certified. Not to mention, any patient that comes to you, would have to pay you cash since Medicare/Medicaid won't let you bill them without board certification and most insurance companies follow their lead so you wouldn't be able to bill them either...
AS
