A spinal implant having a smaller transverse cross-sectional dimension in the radially compressed configuration than in a first expanded configuration and a more linear configuration in the second delivery configuration than in the first curved configuration. The implant assumes the radially compressed configuration and second delivery configuration during delivery to the disc space and assumes the first curved configuration and first expanded configuration upon placement within the disc space. The implant further moves towards the radially compressed configuration once implanted in response to a load placed on the implant by the vertebral bodies.

Nucleus pulposus implants that are resistant to migration in and/or expulsion from an intervertebral disc space are provided. In one form of the invention, an implant includes a load bearing elastic body surrounded in the disc space by an anchoring, preferably resorbable, outer shell. In certain forms of the invention, the elastic body is surrounded by a supporting member, such as a band or jacket, and the supporting member is surrounded by the outer shell. Kits for forming such implants are also provided. In another form of the invention, an implant is provided that has locking features and optional shape memory characteristics. In yet another aspect of the invention, nucleus pulposus implants are provided that have shape memory characteristics and are configured to allow short-term manual, or other deformation without permanent deformation, cracks, tears, breakage or other damage. Methods of forming and implanting the implants are also described.

Nucleus pulposus implants that are resistant to migration in and/or expulsion from an intervertebral disc space are provided. In one form of the invention, an implant includes a load bearing elastic body surrounded in the disc space by an anchoring, preferably resorbable, outer shell. In certain forms of the invention, the elastic body is surrounded by a supporting member, such as a band or jacket, and the supporting member is surrounded by the outer shell. Kits for forming such implants are also provided. In another form of the invention, an implant is provided that has locking features and optional shape memory characteristics. In yet another aspect of the invention, nucleus pulposus implants are provided that have shape memory characteristics and are configured to allow short-term manual, or other deformation without permanent deformation, cracks, tears, breakage or other damage. Methods of forming and implanting the implants are also described.

A method for implanting a prosthetic spinal disc nucleus in an intervertebral disc nucleus space generally includes: (a) making a hole in the annulus of a disc, with the hole having an undilated size that is smaller than the cross-sectional size of a folded prosthetic disc nucleus; (b) using an implant instrument to dilate the hole in the disc annulus; (c) using the implant instrument to pass a straightened prosthetic disc nucleus through the dilated hole and into the disc nucleus space; (d) withdrawing the implant instrument and allowing the hole in the disc annulus to return to a size smaller that its dilated size; and (e) causing or allowing the prosthetic disc nucleus to assume a folded configuration with a cross-sectional size that is larger than its straightened size. A device for use in the method is also disclosed.

A pseudo arthrosis device disposed in a patient between two adjacent vertebrae. The device has an enclosure with a plurality of compressible flexible members packed longitudinally therein. The enclosure is attached to at least one of the adjacent vertebrae. A method of use is disclosed.