Rakmala,
I am in similar shoes as you but have this three points to offer:
1. Your most important letters, unless you've done Nobel prize winning work, are your clinical ones and especially those from surgeons and especially especially those from orthopods. I would say, send the PhD letter as a fourth to every program unless, of course, they say "three only" and make the first three surgical/ortho.
2. As Dr. Zuckerman from HJD clearly points out in his book, you are still applying for a clinical residency even if you have a PhD--and apparently, phuders haven't been so stellar in respecting this aspect of the process. The number one goal should be to show clinical excellence be it LORs, grades etc.
3. The PhD speaks for itself because it is rare. However, I have been told that you should have some sort of qualifier that speaks to the quality of your work--an indication that you didn't stumble through your research. One way to bolster your degree is to get a fabulous LOR from your research advisor. Another, since most pods won't be able to distinguish a Molecular Cell paper from a FEBS letter (could work for or against you), is to have lots of pubs--let your CV do the talking. All in all, show rigor and excitement in your research with an eye for clinical relevance. The research oriented PDs are looking for future colleagues not lab geeks that they can't communicate with.
-FB
PS I agree with Orthopedics. For instance, if your PI has collaborated with or personally knows Reddi and you're applying to UC Davis, you better be asking for a letter or a phone call.
