Three words:
Don't be weird.
In all seriousness, you have WAY more to lose with your PS than to gain. Be sincere and explain why you chose ortho, but do NOT try too hard to stand out. I have read everything from poems, to one dude who "arranged" his in the form of a musical work to emphasise his interest in music. As residents, when we all sat around looking at applications for those coming to interview, the ONLY personal statements that got brought up were the far-out ridiculous ones that we all passed around for a good laugh. No matter how clever you may think you are being, odds are, most will read your "unique" PS and write you off for a fruit. There is only one thing worse than reading one more "I knew I was destined for Orthopedics the instant I heard my ACL pop" and that is reading a bizare, off the wall PS from an otherwise competitive candidate.