As I see it, if he gets there and is in too much pain to drive home, then he has to wait until you can come get him, call a cab, or get one of the assistant couches to drive him home. I would not let his stubborness ruin my appointment. (In truth, I have been your husband's position and partner has been in yours. I went, I figured it out. If her appointment was ruined, I thought that was her deal, not mine).
Or ask him to practice locking and unlocking the brace to ease your worries.
I doubt I am in the majority here.