We are leaving for a cruise from Charleston in February, is a medical card needed if one of my guests have titanium rods in their leg to pass through the metal detectors?

That I am not sure of. I would call your cruise carrier and ask

No certificate needed. I have a titanium hip and had no problems.

Yes no problem tell then you have a titanium hip and they will wand your hip to verify and send you on through! Charleston port was great, the Port Security was sportin' a titan hip himself, he could relate, true story!

We left for our cruise December 31. Customs and boarding was laid back and easy going. They'll probably pull your guest aside and use a hand held wand to insure that it's actually the leg. Now when boarding the ship after docking in the Bahamas, they were much more thorough and "nitpicky". If documentation is handy, I would, if not, I wouldn't worry too much.