Expandable fusion cage

• US 6,582,467 B1
• Filed: 10/31/2001
• Issued: 06/24/2003
• Est. Priority Date: 10/31/2000
• Status: Active Grant

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Vertelink Corporation (Medtronic Plc)
• Inventors: Nguyen, Thanh V., Teitelbaum, George, Shaolian, Samuel M., Pham, To V.
• Primary Examiner(s): Lewis, Ralph A.
• Application Number:
  US10/003,727
• Time in Patent Office: 601 Days
• Field of Search: 623/17.11, 623/17.12, 623/17.13, 623/17.15, 623/17.16, 606/61
• US Class Current: 623/17.11
• CPC Class Codes: A61B 17/1615 Drill bits, i.e. rotating tools extending from a handpiece to contact the worked material
• CPC Class Codes: A61B 17/1631 Special drive shafts, e.g. flexible shafts A61B17/1642, A61B17/164 take precedence
• CPC Class Codes: A61B 17/1642 for producing a curved bore
• CPC Class Codes: A61B 17/1671 for the spine
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61B 2017/00557 inflatable A61B2017/22051 takes precedence
• CPC Class Codes: A61F 2/441 made of inflatable pockets or chambers filled with fluid, e.g. with hydrogel
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/4465 having a circular or kidney shaped cross-section substantially perpendicular to the axis of the spine
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/2821 Bone stimulation by electromagnetic fields or electric current for enhancing ossification
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30451 soldered or brazed or welded
• CPC Class Codes: A61F 2002/30579 with mechanically expandable devices, e.g. fixation devices
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30784 Plurality of holes
• CPC Class Codes: A61F 2002/30841 Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/30919 Sleeves
• CPC Class Codes: A61F 2002/3097 using laser
• CPC Class Codes: A61F 2002/448 comprising multiple adjacent spinal implants within the same intervertebral space or within the same vertebra, e.g. comprising two adjacent spinal implants
• CPC Class Codes: A61F 2220/0058 : soldered or brazed or welded
• CPC Class Codes: A61F 2310/00017 : Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys

Abstract

Disclosed is an expandable fusion cage which facilitates the fusion of adjacent bony surfaces, preferably those in the spine. In a preferred embodiment, the fusion cage. The surfaces of the cage which are intended to contact the vertebral endplates have multiple portions cut out of the metal to form sharp barbs. As the cage is expanded to come into apposition with endplates above and below, the sharp barbs protrude into the subcortical bone of the vertebral body thus securing the cage in place. Multiple holes or fenestrations are present on the superior and inferior surfaces of the cage to permit contact of morselized autologous bone and/or an artificial bone matrix material with the prepared endplate surface.

Claims

1. An expandable fusion cage, comprising:

a tubular body having first and second open ends and a wall surface disposed between the first and second ends, the wall surface being formed by a plurality of intersecting elongate members, at least some of the elongate members intersecting with one another intermediate the first and second ends of the tubular body and said wall surface defining a space inside the body;

the wall surface having a superior portion and an inferior portion, wherein the superior and inferior portions are opposite each other, the superior and inferior portions each having an outer surface having a plurality of barbs thereon extending away from the tubular body; and

the space inside the body being filled with a natural and/or artificial material to stimulate bone growth;

wherein the tubular body has a first diameter which permits delivery of the tubular body into a space formed between two vertebral bodies and a second, expanded diameter, wherein expansion of the tubular body expands the space between the two vertebral bodies.

2. An expandable fusion cage according to claim 1, wherein the plurality of elongate members are a plurality of wires.

3. An expandable fusion cage according to claim 2, wherein the wires are fixedly secured to one another where the wires intersect with one another.

4. An expandable fusion cage according to claim 1, wherein the plurality of elongate members are a plurality of thin bars which are fixedly secured to one another where the bars intersect with one another.

5. An expandable fusion cage according to claim 1, further comprising a capsule surrounding the material to stimulate bone growth, wherein the portions of the capsule directly adjacent to the tubular body comprise a relatively impermeable thin layer of material and the portions of the capsule adjacent to the first and second open ends comprise a material permeable by the material to stimulate bone growth.

6. An expandable fusion cage according to claim 1, wherein the cage is self-expanding.

7. An expandable fusion cage according to claim 1, wherein the cage is expanded with the aid of a balloon.