An inter-vertebral disc prosthesis intended for percutaneous deployment comprises an expandable annular enclosure and an expandable nuclear enclosure. The expandable annular enclosure incorporates a reinforcing annular band along its periphery and is filled with in-situ curable rubber. The expandable nuclear enclosure is filled with a gas. The nuclear prosthesis further incorporates a novel, integrally molded sealing valve assembly and is stretchable and collapsible into a minimal profile for ease of insertion into a specially designed delivery cannula, and is inflation-assisted expandable into an inter-vertebral disc in which complete percutaneous nuclectomy has been performed.