Method and apparatus for intervertebral implant anchorage
Methods and devices are provided for intervertebral implant anchorage. An implantable device for insertion into an intradiscal section between adjacent vertebrae is provided. The implantable device includes at least one anchor plate which comprises 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; and an intradiscal component coupled to the anchor plate.
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 INVENTIONBack 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 annulus fibrosis surrounds the nucleus pulposus and resist torsional and bending force applied to the disc. Vertebral end-plates separate the disc from the vertebra 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 implant 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 INVENTIONAn 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 vertebrae without first creating one or more holes in the vertebrae for the anchoring elements.
In yet another embodiment, the implantable device includes an intradiscal component. Examples of intradiscal components include an—intradiscal spacer, a cage, and an artificial disc.
In yet another embodiment, the implantable device includes first and second anchor plates, inserting including positioning the first anchor plate adjacent a first of the adjacent vertebra and positioning the second anchor plate adjacent a second of the adjacent vertebra, and causing including causing anchoring elements on the first anchor plate to be introduced into the first vertebra and causing anchoring elements on the second anchor plate to be introduced into the second vertebra.
In the apparatuses and methods of the present invention, the plate member preferably has a non-smooth surface so as to promote ingrowth of bone material on the surface. The plate member also preferably has at least one hollow bore through the plate to allow ingrowth of bone material through the plate to the end plate of the vertebra.
The anchoring elements can have a plurality of shapes including cone, cylinder, triangle, square, rectangle and other irregular shapes so long as the anchoring elements are capable of being introduced into an end plate of a vertebra. The anchoring elements can extend from the plate member substantially vertically, angularly or curved. The anchoring elements are preferably shaped so as to minimize the risk of splintering the vertebra by introducing the anchoring elements into the vertebra.
The apparatuses and methods of the present invention may be used for a variety of medical procedures in spine surgery. For example, the anchor plate may be used to secure an implant inserted between adjacent vertebrae, the implant including bone grafts, artificial annular plugs, compressible fusion material, artificial intravertebral disc or other prosthetic devices. The implantable device may be used to replace the damaged and/or malfunctioning intravertebral disc with an artificial disc attached to the anchor plate on the device, or to replace the whole vertebral body with an artificial vertebra which is biomechanically compatible to the spine. The implantable device can be customized to the individuals being treated. In one embodiment, the anchor plate has substantially the shape of a naturally-occurring intervertebral disc and the size of the patient's disc.
Additional advantages of the present invention are set forth in the description which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 5A-D illustrate an implantable device having a cage.
FIGS. 7 A-E illustrate assembly of an implantable device.
FIGS. 9A-D illustrate a method for implanting an implantable device according to the present invention.
The present invention relates to devices which may be anchored to vertebrae of the spine by introducing anchoring elements through an end plate of the vertebrae. In particular, an anchoring plate, which comprises a plurality of anchoring elements such as spikes or prongs extending from the plate, is provided for anchoring an intradiscal device to an end plate of a vertebra. By securing the anchor plate to an end plate of the vertebra, a surgeon operating on a patient's spine can attach a variety of intradiscal components to the anchor plates. The secured anchorage and support provided by the apparatus of the present invention prevents loosening of the apparatus and enhances the fusion of the adjacent vertebrae.
A variety of intradiscal components can be incorporated into the apparatus of the present invention. In one embodiment, the intradiscal component includes a cage within which the anchor plate is contained. Bone graft material can be filled into the cage which is attached to and stabilized by the anchor plate on an end plate of a vertebra, thereby promoting bone ingrowth through the holes on the cage. Alternatively, an artificial intravertebral disc can be included in the apparatus.
It should be noted that other intervertebral fusion devices may also be attached to the anchor plate for restoring or maintaining the normal geometry of the intradiscal space, such as disc height and sagittal angle. Moreover, an artificial vertebral body which is biomechanically compatible with the spine may be attached to the anchor plate to replace a damaged vertebra and restore normal functions to the spine.
One embodiment of the invention is illustrated in
Alternatively, the implantable device according to the present invention may also be sized to a hemicycle or hemioval. As illustrated in
In another embodiment, as illustrated in
In yet another embodiment, as illustrated in
An illustration of an embodiment of an anchor plate is illustrated in
The anchor plate 70 includes at least two anchoring elements 74 distributed on the surface 71 of the plate member 72. The anchor plate may have any regular shape: round, square, rectangle, elliptical, or an irregular shape. The anchor plate is preferred to have a surface area between about 5 mm2-40 mm2; and a thickness preferably between about 1 mm-10 mm, more preferably about 5 mm.
The anchoring elements 74 are preferred to be sharp spikes having a cone, cylinder, square or rectangle shape. The height and width of the anchoring elements are preferably between about 0.5 mm-15 mm, 0.3 mm-15 mm, respectively.
In a preferred embodiment, the anchoring element 74 includes a lumen 80. The lumen preferably has a diameter between about 0.5 mm-9 mm. The lumen allows ingrowth of the bone graft material through the lumen to the end-plate of the vertebra. The lumen also facilitates entry of the anchoring element into the end plate without splintering the vertebra. The surface of the lumen is preferably rough.
The distal portion 77 of the anchoring element 74 may be straight or curved. The surface 79 of the anchoring element 12 is preferred to have a smooth outer surface to facilitate penetration of the element 74 into the end plate E4. In particular, the surface 79 of the anchoring element 74 is preferred not to have a thread for screwing the element 74 into the end plate E4.
The anchoring elements 74 may extend from the plate member 11 substantially vertically, angularly or curved. The direction of the force used to cause the anchoring elements to enter the vertebra will depend—on the shape and angular positioning of the anchoring elements.
The materials used to construct the anchor plate and the implantable device are preferred to be able to endure the stresses and environment to which a vertebra implant is subjected. In addition, such materials should be biocompatible, and substantially chemically inert so as not to cause any detrimental effect to the patient in whom the device is implanted. The anchor plate and implantable device may be made of radiolucent material such as carbon fiber reinforced polymers known commercially as “Peek∞ (polyetherether ketone) or “Ultrapek” (polyether ketone, ether ketone, ketone), polycarbonate, polyprophylene, polyethylene and polysulfone plastics material filled with glass or carbon fibers, or traditional orthopaedic implant material such as nickel stainless steel, titanium alloy, heavy plastic polymer, ceramic, etc. One of ordinary skill in the art will recognize other suitable materials, for example, a cobalt-chromium alloy or a titanium alloy having 4% vanadium and % aluminum, ceramic material such as aluminium oxide and zirconium oxide. The surface 71 of the anchor plate 70 is preferred to be rough to potentiate bone ingrowth on the side of the plate contacting the end plate E4 of the vertebra L4, thereby strengthening the anchorage to the end plate. The surface 73 of the anchor plate 70 may be porous coated or coated with hydroxyapatite or bioactive proteins (e.g. bone morphogenic protein) to promote bone ingrowth.
FIGS. 5A-D illustrate a preferred embodiment of an implantable device. As illustrated in
FIGS. 5E-G illustrate an alternate embodiment of an implantable device with opposing anchor plates and sidewalls for maintaining a separation between the anchor plates.
Details of the assembly of an embodiment of an implantable device are illustrated in FIGS. 7A-C. According to this embodiment, the implantable device 130 includes a first anchor plate 132, a second anchor plate 134, and a cage comprising an upper cover 138 and a bottom plate 140 (
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 implantable device comprising an anchor plate comprising of 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.
Another method is 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 implantable device comprising
- a first anchor plate comprising of 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;
- a second anchor plate comprising of 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 first and second anchor plates to be introduced into the vertebrae through the vertebral end plate.
As illustrated in
As also illustrated in
As also illustrated in
In yet another embodiment according to the method, the implantable device includes an intradiscal component. Examples of intradiscal components include an intradiscal spacer, a cage, and an artificial disc.
In yet another embodiment according to the method, the implantable device includes first and second anchor plates, inserting including positioning the first anchor plate adjacent a first of the adjacent vertebra and positioning the second anchor plate adjacent a second of the adjacent vertebra, and causing including causing anchoring elements on the first anchor plate to be introduced into the first vertebra and causing anchoring elements on the second anchor plate to be introduced into the second vertebra.
As illustrated in
FIGS. 9A-D illustrate a method for implanting a device via anterior approach. As illustrated in
As illustrated in
While the present invention is disclosed by reference to the various embodiments and examples detailed above, it should be understood that these examples are intended in an illustrative rather than limiting sense, as it is contemplated that modifications will readily occur to those skilled in the art which are intended to fall within the scope of the present invention.
Claims
1-40. (Canceled)
41. A method of implanting an intervertebral device, comprising:
- accessing an implantation site:
- attaching a first anchor plate to an end plate of a first vertebrae:
- attaching a second anchor plate to an end plate of a second vertebrae; and
- detachably securing an intervertebral device to the implanted first and second anchor plates.
42. The method of claim 41 further comprising accessing the implantation site via an anterior approach.
43. A method claim 42 further comprising:
- anteriorly exposing the implantation site:
- identifying a vertebrae to be removed from the implantation site:
- surgically removing the vertebrae to be removed: and
- preparing the end plates of the first and second vertebrae to receive the intervertebral device.
44. A method of implanting an intervertebral device, comprising:
- accessing an implantation site:
- removing a dysfunctional vertebrae:
- attaching a first anchor plate to an end plate of a first vertebrae:
- attaching a second anchor plate to an end plate of a second vertebrae, and
- detachably securing an intervertebral device to the implanted first and second anchor plates.
45. The method of claim 44 further comprising anteriorly accessing the implantation site.
Type: Application
Filed: Jul 19, 2004
Publication Date: Feb 3, 2005
Inventors: Lytton Williams (Rolling Hills Estates, CA), Robert Watkins (South Pasadena, CA)
Application Number: 10/894,914