I assume, TWR, that you have no close dealings with disabled people. they're not aliens. they are just people like you and I, with some kind of "difference". mostly, they are happy to laugh with people. that is totally different to being laughed "at".
No, id offer them my help and be concerned that they had hurt themselves.
Why would i laugh?
Last time i fell over in the street there was no one to help me at all and a few days later i had two lovely black eyes, smashed my glasses too!