That's not true, and it's a good thing it's not. Two scenes i can immediately think of, one right at the start when they are in a shop and skylar is helping junior put on trousers and there's some dicks taking the piss, who Walter gives a dead leg to. Second one is when Walter is trying to teach junior to drive.
It's a good thing cos disabilities cause people problems and affect their lives. These effects should be portrayed, otherwise it plays to the idea that disabilities aren't a problem, don't need anything special or different done around them to remove/ease those problems etc., it just wouldn't be right for a disabled character to never have their disability mentioned.