The present invention provides intervertebral disc nucleus inserts that
may fully or partially replace the natural, or native, intervertebral
nucleus. The present invention may include a hydrogel bag outer body that
includes an interior cavity for introducing a spiral implant device. The
hydrogel bag may be introduced through a cannula into the intervertebral
space after a cavity of a desired shape and size has been cleared. The
combination of the spiral implant resting configuration and the hydrogel
bag substantially fills the cavity. The combination of the spiral implant
and the hydrogel bag may improve upon 1) implant expulsion or extrusion;
2) implant sizing; 3) implant conformity; and 4) reduction or prevention
of bone edema. In further embodiments the hydrogel bag may include an
inner and outer layer or two complimentary bags joined into one structure
to better distribute the load between the vertebral endplates.