If we’re looking for people with medical conditions who can’t move, Morrisey’s Girlfriend in a Coma might qualify.
It’s serious.
Todd Rundgren wrote a song called “Hawking” about Stephan Hawking.
Whenever I…
I close my eyes
Then I don’t mind being the way I am
But whenever I try
Explaining why
I know I never can
[snip]
I see time without beginning
Space without an ending
I see bodies strong and running
With minds not comprehending
Have pity on your brother
Please have pity on your sister
Take pity on each other
And on every living creature
How did he smell?
“Up on Cripple Creek”?
:d&r:
From James Taylor, The Frozen Man:
You can raise your arm, you can wiggle your hand (unlike myself)
So wave goodbye to the frozen man
I know, I know, it’s really serious. 
The Faint, Ballad of a Paralysed Citizen
Does being messed up by polio count?
Ian Dury and The Blockheads’ Spasticus (Autisticus).
CMC +fnord!
The Army Dopers should know this one:
*My girl’s a pretty girl
Lives in a hospital
She is a vegetable
She has no arms or legs
All she has are sticks and pegs
I’d give her anything to keep her alive
My girl’s a pretty girl
Lives in a hospital
She has her own TV
And it’s called an EKG
I’d give her anything to keep her alive. * 
SSG Schwartz
Handicap and Equality by Peter Hammill is about all sorts of disability, not only physical.
Terrible!
How about “Mr. Crump’s Iron Lung” by Weird Al Yankovic?
How about “Paralyzed”, by the Legendary Stardust Cowboy?