I am carrying a fair amount of steel in my lower body (ex-motorcycle road racer).
I have had several MRIs with the steel in place.
The technicians take great care to make sure NOT to do the MRI on the actual body part with the steel in it (i.e. I go in head first and they do not let my legs actually go into the machine). But, I THINK the fact that everything is stainless steel (non-magnetic) provides a fair level of protection.
IN any case, I have never had a plate or screw come flying out through my flesh.
I had two MRI’s, one on my stomach and one on my brain, with a surgical steel earring in place because it was the captive-bead style and neither I nor the nurse could figure out how to remove it, and she eventually asked me what it was made of and said that if it was surgical steel it shouldn’t be an issue, and surprisingly enough, it wasn’t. I did make sure to wear stuff like sweatpants and slip-on tennis shoes, though.