I'd like this to only be a character, not a fursona please. Some names you could call him that I really like are- Astar, Rion, Rebtin. I'm gonna call him Astar for his backstory.
Backstory Time!
Astar walked through the seldom-used streets, a swagger in his step. He looked around, then began howling up at the moon, which had just appeared in the sky. He stopped by a barbed wire fence, and began licking his paw happily. Suddenly, a car tore towards him, ripping off his leg into two sections, the middle part lost. The driver leaped out, and dialed 911 for him. He passed out, howling and yipping with pain.
The next thing he knew, he awoke in a hospital-type place, his leg very strange looking. The bottom section had been found, but the middle had not, and in its place was a Plexiglas tube, filled with some odd liquid, and floating red and blue discs. His real bone, however, was sticking in the tube. A nurse walked in, and began explaining to him what happened, though he didn't understand a word.
"You ripped the middle part of your leg off," she said with a sympathetic frown. "This tube is filled with a liquid that will obey your mind's commands, and the red and blue discs are to preserve the liquid so it doesn't spoil." She had him go through therapy, learning how to work with the new leg, and then he was released back into the wild, far from any streets.
It fails, but explains the leg-cuff.
Lines (c) Neara, ideas (c) me.