It's my experience, after interviewing about 50+ applicants & subsequently reading many PS's, special interest in osteopathic medicine not essential in a PS. If you are adding it just to add it b/c you think that the adcom/interviewers care about it...DON'T.
I would say that there have only been about 3-5 PS's (that I've read) that have included osteopathic intent that have been beneficial to their application. The vast majority of the time it comes off as an obligatory remark that can actually turn me off to an application.
It's called a Personal Statement for a reason; unless osteopathic medicine is something that makes you who you are, leave it out. Goals, drives, motivations, triumphs, downfalls...those are the things, IMO, that make a person who they are & something that many more people would enjoy reading about than some obligatory remark about "I believe in the Osteopathic 'philosophy' of being 'holistic' & 'treating the whole person'..." If I read that one more freaking time, I am going to puke.