There has never really been one.
We have actual, workable prosthetic legs, but the arms, not so much. For one thing, they attach poorly -- someone with a prosthetic arm can't really lift more than about 8 pounds with their prosthesis, so any type of heavy work is right out. For another, you have to learn to operate them by operating different muscles -- you squeeze a muscle in your back to flex your elbow, you shrug a muscle in your shoulder to turn your wrist, etc.
Well, Mr. Researcher guy was told to take whatever resources he needed, but the government wanted a functional prosthetic arm in eight years.
What he has done is called "Targeted Muscle Reinnervation" -- he attaches the motors in the prosthetic directly to nerves elsewhere, in a way that enables the arm to be controlled without having to actually work muscles elsewhere. You just *think* "Open my hand" and your prosthetic hand opens.
He has expanded the possible range of motions and commands available to arm prosthesis wearers hugely.
The attachment problem, I don't really know about. I haven't seen much on that.
But here's a piece on the latest research on TMR, and how well it's working:
There's that doctor in China, , who has successfully taken the nerves from a patient's thigh and attached them to the bladder, such that these patients achieve more-or-less normal control of their bladders. They scratch their thigh, and their bladders empty. It's revolutionary, but comes with a cost: some loss of voluntary control of the muscle of the thigh.
Here is MY question.
Can the TMR method, which does not seem to involve any loss of function in the nerves used to re-innervate the arm, be used to re-innervate the bladder and bowel of people with spinal cord damage, without any loss of function in whatever nerve you're going to hook the bladder up to?
I think this guy at Johns Hopkins needs to talk to the guys who are working on the Chinese bladder reinnervation method. I really, really think those folks need to be comparing notes.