This is an extraordinarily common ocurrence and no reason to cancel your trip. Also, absolutely no reason to put yourself at risk of re-injury if you are non-weight bearing.

There are two easy options:

1. Tell the Officer checking ID's when you reach the podium that you will need assistance. S/he will call a supervisor and you and the supervisor can work that out. If you want to remove the brace and walk, that's your choice, but it really has to be your choice and you've got to appreciate that lines get held up and things happen.

2. Get wheelchair assistance.

Whatever you do, give yourself lots and lots and lots of time. Everything takes exponentially longer and hurrying is the mistake.