Ted raises his eyebrows at her. "You sure? Cause I'm going to be hopping around carefully with one crutch, since I can't catch you if I use both," he points out.

He's not entirely confident without Sherlock on the other side, so he wants to make sure she thinks she's strong enough to make it there. And is aware of the fact that he'll be of limited help. If he was alright, he would gladly piggyback her there, but...