"Lip" by Kathy Fish in Fictionaut

Last night Tom'd been beaten up by a guy with pointy teeth. He'd yanked Tom's arm high up behind his back. Luckily, the arm had two years before been paralyzed by a stroke, so he felt no pain, only a strange airy feeling when the shoulder joint had been forced out of its socket, as if a hole had been drilled through his skin. Read story here.