In my opinion that’s horrible advice. It’s almost the worst advice an aspiring PM&R resident could be given. We’re just about the least “gunnerish” specialty out there—I’m honestly not sure if someone can actually be a gunner and be in PM&R—we’re just not the sort of specialty to appeal to that type of personality, just like FM wouldn’t appeal to gunners as well.
There is certainly some overlap tween ortho and PM&R, but there are a lot of differences. In the past, PM&R was essentially a guaranteed backup for students who wanted to match ortho but failed, and I’m guessing that’s where the advice came from. However this is no longer the the case-we’re still a fairly uncompetitive specialty stats-wise, but as far as the number of applicants to available positions we’re among the more selective specialties and few programs will want someone who they think is going into PM&R as a backup-there’s always a chance such a person will not stay in the program. There are plenty of applicants with good test scores who want to be in PM&R, so why risk offering an interview to someone who may not keep the interview/rank the program/stay if matched? Too many “what if’s?”...
The best advice is to shadow physiatrists and get to know PM&R. Do a rotation. Study, do well on boards, and have a genuine interest in PM&R. Explore ortho and other specialties if you’re interested in them, but try to avoid giving the impression PM&R (or any specialty for that matter) is a backup.
Honestly that’s pretty much all you need to do—with decent stats and a cooperative personality most can match into PM&R just fine. High stats/some research or other stuff that helps you stand out will be needed to get into the top programs.