Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Reexamination Certificate
2000-08-22
2004-10-05
Shaver, Kevin (Department: 3732)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
Reexamination Certificate
active
06800092
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to methods and devices for treating intervertebral disc diseases and more particularly to intervertebral prostheses for positioning in an intervertebral space to treat intervertebral disorders.
BACKGROUND OF THE INVENTION
Back pain remains a major public health problem, especially among aged people. Persistent and severe back pain often causes debility and disability, and such a pain is closely associated with intervertebral disc abnormalities of the spine.
The human spine is a flexible structure comprised of thirty-three vertebrae. Intervertebral discs separate and cushion adjacent vertebrae, and act as shock absorbers and allow bending between the vertebrae. An intervertebral disc comprises two major components: the nucleus pulposus and the annulus fibrosis. The nucleus pulposus is centrally located in the disc and occupies 25-40% of the disc's total cross-sectional area. The anuulus fibrosis surrounds the nucleus pulposus and resist torsional and bending force applied to the disc. Vertebral end-plates separate the disc from the vertebrae on either side of the disc.
Because of exertion, injury, illness, accident or abuse, one or more of the vertebrae and/or one or more discs may become damaged and malfunctioning. Specifically, disorders of the vertebrae and discs include but are not limited to 1) disruption of the disc annulus such as annular fissures; 2) chronic inflammation of the disc; 3) localized disc herniations with contained or escaped extrusions; and 4) relative instability of the vertebrae surrounding the disc.
Various approaches have been developed to treat back pain. Minor back pain can be treated with medication and other non-invasive therapy. However, it is often necessary to remove at least a portion of the damaged and/or malfunctioning back component. For example, when a disc becomes ruptured, the ruptured disc may be surgically removed and the two vertebrae between the removed disc fuse together. In one approach, the end plates of two adjacent vertebra are fused posterior-laterally by screws. However, such posterior fusion with rigid end-plate fusion can be associated with pseudoarthrosis.
To promote fusion or arthrodesis across the intradiscal space, intervertebral implants are used to support and fuse together adjacent vertebrae by posterior-fusion or anterior grafting. For example, surgical prosthetic implants for vertebrae described in U.S. Pat. No. 5,827,328 include rigid annular plugs that have ridged faces to engage adjacent vertebrae to resist displacement and allow ingrowth of blood capillaries and packing of bone graft. These annular implants are usually made of biocompatible carbon fiber reinforced polymers, or traditional orthopaedic implant materials such as nickel, chromium, cobalt, stainless steel or titanium. The individual implants are internally grooved and are stacked against each other to form a unit between the two adjacent vertebrae. One of the disadvantages of these interlocked implants is that, the implants may not be stable enough to withstand rotation and may lead to implant loosening and failure of the prosthesis.
Another intervertebral fusion device described by Kozak, et al. (U.S. Pat. No. 5,397,364) includes an assembly of two lateral spacers and two central spacers, which defines a channel in the center of the fusion device for insertion of the bone graft material. The spacers are maintained in their configuration within the intradiscal space by screws threaded into a vertebra from the outside of the disc. A disadvantage of this device is a tendency for the anchoring screws to become dislodged.
SUMMARY OF THE INVENTION
An anchoring plate is provided for anchoring an intradiscal device to an end plate of a vertebra. The anchoring plate includes a plate member sized to be positioned within an intradiscal section between adjacent vertebrae and a plurality of anchoring elements extending from a surface of the plate member, each anchoring element including a distal portion capable of being introduced into the vertebra through the vertebral end plate. In one embodiment, at least one of the anchoring elements includes a lumen. The lumen allows ingrowth of the bone graft material through the lumen to the end-plate of the vertebra. The lumen preferably has a diameter between about 0.5 mm-9 mm.
An implantable device for insertion into an intradiscal section between adjacent vertebrae is also provided which includes an anchor plate comprising of a plate member sized to be positioned within an intradiscal section between adjacent vertebrae and a plurality of anchoring elements extending from a surface of the plate member, each anchoring element including a distal portion capable of being introduced into an end plate of one of the adjacent vertebrae; and an intradiscal component coupled to the anchor plate. In one embodiment, the intradiscal component includes a spacer separating the anchor plate from the end plate of the other adjacent vertebra. In another embodiment, the intradiscal component includes a cage having a first side for positioning adjacent a first vertebra and a second side for positioning adjacent a second vertebra, the first side including a plurality of holes through which the anchoring elements on the anchor plate can be positioned, and the second side including at least one hollow bore for ingrowth of bone material. In yet another embodiment, the intradiscal component includes an artificial disc.
Another implantable device for insertion into an intradiscal section between adjacent vertebrae is provided which includes a first anchor plate comprising a plate member sized to be positioned within an intradiscal section adjacent a first vertebrae and a plurality of anchoring elements extending from a surface of the plate member, each anchoring element including a distal portion capable of being introduced into an end plate of the first vertebra; a second anchor plate comprising a plate member sized to be positioned within an intradiscal section adjacent a second vertebrae and a plurality of anchoring elements extending from a surface of the plate member, each anchoring element including a distal portion capable of being introduced into an end plate of the second vertebra; and an intradiscal component coupled to the first and second anchor plates. In one embodiment, the intradiscal component includes a spacer separating the first anchor plate from the second anchor plate. In another embodiment, the intradiscal component includes a cage having a first side for positioning adjacent the first vertebra and a second side for positioning adjacent the second vertebra, the first and second sides each including a plurality of holes through which the anchoring elements on the first and second anchor plates can be positioned. In yet another embodiment, the intradiscal component includes an artificial disc.
A method is also provided for anchoring an implantable device within an intradiscal section between adjacent vertebrae which includes:
creating a space between adjacent vertebrae;
inserting into the space created an intradiscal device comprising an anchor plate comprising a plate member sized to be positioned within the space and a plurality of anchoring elements extending from a surface of the plate member, each anchoring element including a distal portion capable of being introduced into an end plate of one of the adjacent vertebrae; and
causing the anchoring elements on the anchor plate to be introduced into the vertebrae through the vertebral end plate.
In one embodiment according to the method, the anchoring elements are introduced into the vertebrae by applying a force to the anchor plate, anchor plate having a vector positioned entirely within the intradiscal space. In one variation, the force is applied to the anchor plate approximately perpendicular to a plane of the end plate,
In another embodiment, the anchoring elements are introduced into the vertebrae without rotating the anchor elements.
In yet another embodiment, the anchoring elements are introduced into the ve
Watkins Robert G.
Williams Lytton A.
Priddy Michael B.
Shaver Kevin
Swienton, Esq. Brian F.
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