Reinforced expandable cage and method of deploying

An expandable intervertebral prosthesis with increased axial stability in a direction substantially parallel with a longitudinal spinal axis, said prosthesis comprising:

• a first cage in an unexpanded state, said first cage adapted to be placed in an intervertebral position within a spine, and then caused to expand to an expanded state;
• a second cage placed inside said first cage in said expanded state such that when both said first cage is in said expanded state and said second cage is in an expanded state, they together form an assembled cage, said assembled cage defining a substantially hollow central region;
• and
• a reinforcing element that rolls up from an oblong geometry into at least one substantially planar spiral geometry in a force-free state to at least partly fill said substantially hollow central region in said assembled cage, thereby forming a reinforced cage.

An expandable prosthesis for replacement of an intervertebral disc to promote spinal fusion, said prosthesis comprising:

• at least one cage made from a relatively thin walled material, said at least one cage comprising:
• a first, unexpanded state prior to deployment into an intervertebral space;
• and
• a second state wherein after deployment in said intervertebral space, said at least one cage is expanded, thereby defining a substantially hollow central region;
• and
• a reinforcing element disposed within said substantially hollow central region, said reinforcing element comprising:
• a first, oblong state prior to deployment into said substantially hollow central region;
• and
• a second state wherein said reinforcing element assumes a substantially planar spiral configuration upon deployment in said substantially hollow central region, said substantially planar spiral configuration to at least partly fill said substantially hollow central region in such a way as to improve the stability of said expanded at least one cage in a direction substantially parallel to a longitudinal axis of said intervertebral space.

A prosthesis expandable in a plurality of dimensions to promote intervertebral fusion, said prosthesis comprising:

• a cage comprising:
• a first, unexpanded state prior to deployment into an intervertebral space;
• and
• a second, expanded state wherein said second, expanded state comprises at least:
• a first expansion in a direction substantially parallel to a longitudinal axis of said intervertebral space thereby defining a substantially hollow central region;
• and
• a second expansion in a plane normal to said first expansion such that a space formed by said first and second expansions defines a substantially hollow central region;
• and
• a reinforcing element adapted to be disposed within said substantially hollow central region, said reinforcing element comprising:
• a first, oblong state prior to deployment into said substantially hollow central region;
• and
• a second state wherein said reinforcing element assumes a substantially planar spiral configuration upon deployment in said substantially hollow central region, said substantially planar spiral configuration to at least partly fill said substantially hollow central region in such a way as to improve the stability of said expanded cage in a direction substantially parallel to a longitudinal axis of said intervertebral space.

A method of deploying an intervertebral prosthesis, said method comprising the steps of:

• providing a prosthesis, wherein said prosthesis comprises:
• at least one expandable cage that defines a substantially hollow central region upon expansion;
• and
• a reinforcing element adapted to be disposed within said substantially hollow central region;
• and
• an elongate instrument adapted to control said expansion of said at least one expandable cage, said elongate instrument comprising:
• an outer tube;
• a tension wire disposed within and relatively movable to said outer tube;
• and
• a restraining element disposed on said tension wire, said restraining element adapted to engage at least a portion of said at least one expandable cage;
• spreading apart adjacent vertebrae such that an intervertebral space is defined thereby;
• placing said prosthesis in a delivery tube;
• inserting said delivery tube into said intervertebral space;
• controlling the expansion of said at least one expandable cage through limiting the relative movement between said outer tube and said tension wire;
• using said elongate instrument to remove said at least one expandable cage from said delivery tube;
• placing said at least one expandable cage in said intervertebral space;
• expanding said at least one expandable cage;
• and
• inserting said reinforcing element into said substantially hollow central region such that said reinforcing element rolls up from an oblong geometry into at least one substantially planar spiral geometry in a force-free state that at least partly fills said substantially hollow central region.