There are some fans who maintain there is nothing wrong and he is faking it to attract attention and use his 'disablity' to control people. Nor does he take the 'Viacon' pills or whatever they are called . Just another control mechanism. As House would say: "Well Doctor what do you think - if at all?"
When his ex was in it, there was something about her allowing the drs to do some procedure which saved his life, but left him like that. He's also shown his leg off and there was no muscle in the thigh.