The present disclosure concerns implants to at least partially replace the nucleus of a spinal disc. In one embodiment, a prosthetic structure is provided which includes a bag having a fixation component, the bag operable to contain at least one internal implant within the bag. In another embodiment, a bag structure is provided with a flange adaptable to anchor the structure to a vertebral body and a sinusoidal-shaped structure made of a flexible material is provided with various unique configurations. In one embodiment, for delivery, a bag structure with a flange may be attached to a vertebral body. In another embodiment, a sinusoidal-shaped implant structure is alternately woven from one end to the other with a second sinusoidal-shaped structure.