METHOD OF LATERALLY INSERTING AN ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH CROSSBAR SPACER
The present invention is directed to an implant that can be placed between two adjacent vertebral bodies using a lateral insertion method. The implant is characterized as having a first end plate and a second end plate which a crossbar spacer therebetween. The crossbar spacer preferably fits within a channel on the inner surfaces of the first end plate and the second end plate, whereby the spacer allows pivots, twisting and/or rotational movement of the spine. The first end plate and the second end plate include a keel extending therefrom, whereby the keel traverses longitudinally between a first lateral side and a second opposed lateral side and is substantially perpendicular to the sagittal plane of the patient's spine.
This application claims priority under 35 USC 119 to co-pending U.S. Patent Applications No. 60/517,791, filed Nov. 5, 2003 and entitled “ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH CROSSBAR SPACER AND LATERAL IMPLANT METHOD,” (KLYCD-05008US2) and No. 60/517,973, filed Nov. 6, 2003 and entitled “ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH CROSSBAR SPACER AND LATERAL IMPLANT METHOD,” (KLYCD-05008US3) both of which are hereby incorporated by reference.
CROSS-REFERENCE TO RELATED APPLICATIONSThis application is related to U.S. Provisional Application No. 60/422,039, filed Oct. 29, 2002, entitled “ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH TRANSLATING PIVOT POINT AND METHOD,” U.S. patent application Ser. No. 10/684,668, filed Oct. 14, 2003, entitled “ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH CROSSBAR SPACER AND METHOD,” U.S. patent application Ser. No. 10/684,669, filed Oct. 14, 2003, entitled “ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH TRANSLATING PIVOT POINT AND METHOD,” U.S. Provisional Application No. 60/422,011, filed Oct. 29, 2002, entitled “TOOLS FOR IMPLANTING AN ARTIFICIAL VERTEBRAL DISK AND METHOD,” U.S. patent application Ser. No. 10/685,134, filed Oct. 14, 2003, entitled “TOOLS FOR IMPLANTING AN ARTIFICIAL VERTEBRAL DISK AND METHOD,” U.S. Provisional Application No. 60/422,022, filed Oct. 29, 2002, entitled “ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH A SPACER AND METHOD,” U.S. Provisional Application No. 60/422,021, filed Oct. 29, 2002, entitled “ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH CROSSBAR SPACER AND METHOD,” U.S. patent application Ser. No. 10/685,011, filed Oct. 14, 2003, entitled “ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH SPACER AND METHOD,” U.S. patent application Ser. No. ______, filed ______, entitled “LATERALLY INSERTABLE ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH TRANSLATING PIVOT POINT,” (KLYCD-05007US5), U.S. patent application Ser. No. ______, filed ______, entitled “METHOD OF LATERALLY INSERTING AN ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH TRANSLATING PIVOT POINT,” (KLYCD-05007US6), U.S. patent application Ser. No. ______, filed ______, entitled “LATERALLY INSERTABLE ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH A CROSSBAR SPACER,” (KLYCD-05008US6), U.S. patent application Ser. No. ______, filed ______, entitled “LATERALLY INSERTABLE ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH A SPACER,” (KLYCD-05010US4), U.S. patent application Ser. No. ______, filed ______, entitled “METHOD OF LATERALLY INSERTING AN ARTIFICIAL VERTEBRAL DISK REPLACEMENT IMPLANT WITH A SPACER,” (KLYCD-05001US5), all of which are incorporated herein by reference.
FIELD OF THE INVENTIONThe field of art of this disclosure is directed to an artificial vertebral disk replacement and method.
BACKGROUND OF THE INVENTIONThe spinal column is a biomechanical structure composed primarily of ligaments, muscles, vertebrae and intervertebral disks. The biomechanical functions of the spine include: (1) support of the body, which involves the transfer of the weight and the bending movements of the head, trunk and arms to the pelvis and legs, (2) complex physiological motion between these parts, and (3) protection of the spinal cord and nerve roots.
As the present society ages, it is anticipated that there will be an increase in adverse spinal conditions which are characteristic of aging. For example, with aging comes an increase in spinal stenosis (including, but not limited to, central canal and lateral stenosis), and facet joint degeneration. Spinal stenosis typically results from the thickening of the bones that make up the spinal column and is characterized by a reduction in the available space for the passage of blood vessels and nerves. Facet joint degeneration results from the constant load borne by the facet joints, and the eventual wear that results. Pain associated with both conditions can be relieved by medication and/or surgery.
In addition to spinal stenosis and facet joint degeneration, the incidence of damage to the intervertebral disks is also common. The primary purpose of the intervertebral disk is to act as a shock absorber. The disk is constructed of an inner gel-like structure, the nucleus pulposus (the nucleus), and an outer rigid structure comprised of collagen fibers, the annulus fibrosus (the annulus). At birth, the disk is 80% water which then gradually diminishes with time, thereby becoming stiff. With age, disks may degenerate, and bulge, thin, herniate, or ossify. Additionally, damage to disks may occur as a result disease, trauma or injury to the spine.
The damage to disks may call for a range of restorative procedures. If the damage is not extensive, repair may be indicated, whereas extensive damage may indicate full replacement. Regarding the evolution of restoration of damage to intervertebral disks, rigid fixation procedures resulting in fusion are still the most commonly performed surgical intervention. However, trends suggest a move away from such procedures. Currently, areas evolving to address the shortcomings of fusion for remediation of disk damage include technologies and procedures that preserve or repair the annulus, that replace or repair the nucleus, and that advance implants for total disk replacement. The trend away from fusion is driven both by issues concerning the quality of life for those suffering from damaged intervertebral disks, as well as responsible health care management. These issues drive the desire for procedures that are minimally invasive, can be tolerated by patients of all ages, especially seniors, and can be performed preferably on an out-patient basis.
Most recently, there has been an increased interest in total disk replacement technology. A number of artificial disks are beginning to appear in the medical device marketplace. These artificial disks vary greatly in shape, design and functionality. With these devices are available tools and methods for insertion of the devices between the vertebrae.
Accordingly, there is a need in the art for innovation in technologies and methods that advance the art in the area of minimally invasive intervertebral disk replacement. This not only enhances the quality of life for those suffering from the condition, but is responsive to the current needs of health care management.
The following description is presented to enable any person skilled in the art to make and use the implant of the present invention. Various modifications to the embodiments described will be readily apparent to those skilled in the art, and the principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of what is disclosed and defined by the appended claims. Thus, what is disclosed is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein. To the extent necessary to achieve a complete understanding of what is disclosed herein, the specification and drawings of all patents and patent applications cited in this application are incorporated herein by reference.
The implant 100 preferably includes an upper end plate 110 that is configured to mate with an upper vertebral body. The implant 100 preferably includes a lower end plate 120 that is configured to mate with a lower vertebral body. The implant 100 also includes a spacer 130 positioned between the upper end plate 110 and the lower end plate 120. The spacer 130 separates the upper end plate 110 from the lower end plate 120 and also facilitates pivotal and/or rotational as well as twisting movement of the upper end plate 110 and the lower end plate 120 relative to each other and the spacer 130. The spacer 130 is preferably in the form of a crossbar as discussed in more detail below.
The upper end plate 110 has a first outer surface 112 which comes into contact and mates with the underside of the upper vertebral body. The implant 100 includes a first keel 114, as shown in
It is preferred that the first keel 114 of the upper end plate 110 includes a plurality of teeth 115. In one embodiment, the teeth 115 of the keel 114 are angled and point towards the left lateral face of the implant 100, as shown in the example in
The lower end plate 120 of the present implant 100 includes a second outer surface 122, as shown in
It is preferred that the second keel 124 of the lower end plate 120 includes a plurality of teeth 125. In one embodiment, the teeth 125 of the keel 124 are angled and face towards the left lateral face of the implant 100, as shown in the example in
In the embodiment shown in
The first and second keels 114, 124 preferably extend between the vertebral bodies to anchor the implant 100 to the spine. The lateral orientation of the first keel 114 and the second keel 124 allow the implant 100 to be inserted into the spine using a lateral approach as opposed to an anterior or posterior approach, which is advantageous, because the spinal nerves in the spinal cavity are minimally undisturbed when the implant 100 is inserted laterally. In comparison to a posterior insertion approach in which the spinal nerves can be substantially disturbed, the spinal nerves are bypassed and relatively undisturbed when the implant 100 is inserted laterally between the vertebral bodies from the side of the spine. Although an anterior insertion approach has its benefits, the lateral insertion approach can allow the present implant 100, and associated implantation tools, to be inserted into the spine with less disturbance of the patient's internal organs. This can translate into less time and risk associated with preparing the spine for insertion as well as inserting the implant itself into the spine. Further, the laterally oriented first and second keels 114, 124 offer substantial stability to the vertebral bodies during extension, flexion and lateral bending of the spine.
As shown in
As shown in
As shown in
As shown in
In one embodiment, the first outer surface 112 of the first end plate 110 is substantially parallel to the second outer surface 122 of the second end plate 120 when the implant 100 is assembled and is in a neutral position (i.e., the position where the first end plate 110 has not rotated relative to the second end plate 120). Alternatively, the first outer surface 112 of the first end plate 110 is non-parallel to the planar surface of the second outer surface 122 of the second end plate 120 when the implant 100 is assembled and in the neutral position. The non-parallel orientation of the first end plate 110 and the second end plate 120 allows the plates to pivot a greater degree with respect to each other. Additionally, other factors such as the height of the spacer 130 and the position of the keel receiving channels can be adjusted in order to increase the degree by which the first end plate 110 and the second end plate 120 can pivot relative to each other and the spacer 130.
In one embodiment, the planar surfaces which correspond to the first and second outer surfaces 112, 122 of the implant lie parallel or substantially parallel to the axial plane of the body when the implant 100 is inserted between adjacent vertebrae. In one embodiment, the planar surfaces which correspond to the first and second inner surfaces 116, 126 of the first and second end plates 110, 120 lie parallel, or substantially parallel, to the axial plane of the body when the implant is implanted. In one embodiment, the outer surfaces 112, 122 and the inner surfaces 116, 126 both lie parallel or substantially parallel to the axial plane of the body when the implant is implanted. In each of the embodiments, either or both keels 114, 124 are perpendicular to the sagittal plane. Preferably, the keels 114, 124 are also parallel to the coronal plane of the body.
In the embodiment shown in
In another embodiment, the first beam 210 can be positioned transversely along the length of the second beam 220 such that the midpoint 216 of the first beam 210 and the midpoint 226 of the second beam 220 are aligned with one another. Where both beams 210, 220 are positioned at the respective midpoints 216, 226, the crossbar spacer 130 substantially forms a plus sign, “+”.
In constructing the crossbar 130, the first beam 210 can be formed integrally with the second beam 220 to be unitary in construction. Alternatively, the first beam 210 can be adhered to the second beam 220 using any other suitable method (e.g. spot welding). It should be noted that the first beam 210 and the second beam 220, as well as the spacer 130 as a whole, are sufficiently constructed to withstand the load forces applied by the end plates 110, 120 in the neutral position as well as during flexion, extension and/or lateral bending movements. The spacer 130 can be formed by extrusion, injection, compression molding, machining or any other appropriate techniques.
Viewing
As stated above, the crossbar spacer facilitates pivotal or rotational movement of the first end plate 110 and the second end plate 120, relative to each other. In particular, the interface between the first beam 210 of the spacer 130 and the channel 150 allows the upper end plate 110 and/or lower end plate 120 to pivot or rotate about the first beam 210 when the patient moves backwards (extension) and forwards (flexion). Additionally, the interface between the second beam 210 of the spacer 130 and the channel 160 allows the lower end plate 120 and/or upper end plate 110 to pivot or rotate about the second beam 210 when the patient bends side to side (laterally). The patient's weight as well as gravity hold the spacer 130 securely seated within the channels 150, 160. As stated above, the implant 100 includes channels 150, 160 in one embodiment, although not necessarily.
In one embodiment, there is a loose fit between the spacer 130 and the upper and lower end plates 110, 120. In particular, there is a loose fit between the upper beam 210 and the upper channel 150 and also between the lower beam 220 and the lower channel 160. This loose fit allows for a twisting motion of the upper and/or lower end plates, and thus vertebral bodies, about a vertical axis through the center of the spine.
In one embodiment, the implant can be made of medical grade titanium, stainless steel or cobalt chrome. The material has appropriate physical and mechanical properties and is suitable for carrying and spreading the physical load between the spinous process. Other materials that have appropriate structural strength and that are suitable for implantation into a patient can also be used. One class of materials contemplated for use in implant 100 is the class of biocompatible polymers. Copolymers, blends and composites of polymers are also contemplated for fabrication of parts of the disclosed device. A copolymer is a polymer derived from more than one species of monomer. A polymer composite is a heterogeneous combination of two or more materials, wherein the constituents are not miscible, and therefore exhibit an interface between one another. A polymer blend is a macroscopically homogeneous mixture of two or more different species of polymer.
One group of biocompatible polymers are the polyarylesterketones which has several members, which include polyetheretherketone (PEEK), and polyetherketoneketone (PEKK). PEEK has proven as a durable material for implants, as well as meeting criteria of biocompatibility. Medical grade PEEK is available from Victrex Corporation under the product name PEEK-OPTIMA. Medical grade PEKK is available from Oxford Performance Materials under the name OXPEKK, and also from CoorsTek under the name BioPEKK. Other materials that can be used include polyetherketone (PEK), polyetherketoneether-ketoneketone (PEKEKK), and polyetheretherketoneketone (PEEKK), and, generally, a polyaryletheretherketone. Further, other polyketones can be used as well as other thermoplastics.
Reference to appropriate polymers that can be used in the spacer can be made to the following documents, all of which are incorporated herein by reference. These documents include: PCT Publication WO 02/02158 A1, dated Jan. 10, 2002, entitled “Bio-Compatible Polymeric Materials;” PCT Publication WO 02/00275 A1, dated Jan. 3, 2002, entitled “Bio-Compatible Polymeric Materials;” and, PCT Publication WO 02/00270 A1, dated Jan. 3, 2002, entitled “Bio-Compatible Polymeric Materials.”
Still another interesting group of biocompatible polymers are polyalkyl biocompatible polymers, such as polyethylenes, polypropylenes, and the like. These medical grade biocompatible polymers are also available as reinforced polymer materials. To reinforce a polymeric material, fillers, are added to a polymer, copolymer, polymer blend, or polymer composite. Fillers are added to modify properties, such as mechanical, optical, and thermal properties. In this case, fillers, such as carbon fibers, are added to reinforce the polymers mechanically to enhance strength for certain uses, such as load bearing devices.
For example, other grades of PEEK are also available and contemplated, such as 30% glass-filled or 30% carbon-filled, provided such materials are cleared for use in implantable devices by the FDA, or other regulatory body. Glass-filled PEEK reduces the expansion rate and increases the flexural modulus of PEEK relative to that which is unfilled. The resulting product is known to be ideal for improved strength, stiffness, or stability. Carbon-filled PEEK is known to enhance the compressive strength and stiffness of PEEK and lower its expansion rate. Carbon-filled PEEK offers wear resistance and load carrying capability.
Alternatively, the spacer 130 can be made out of a polymer, and more specifically, the polymer is a thermoplastic with the other components made of the materials specified above. Still more specifically, the material is PEEK 450G, which is an unfilled PEEK approved for medical implantation available from Victrex of Lancashire, Great Britain. (Victrex is located at www.matweb.com or see Boedeker www.boedeker.com). Other sources of this material include Gharda located in Panoli, India (www.ghardapolymers.com). Further in this embodiment, the PEEK has the following additional approximate properties:
What has been disclosed herein has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit what is disclosed to the precise forms described. Many modifications and variations will be apparent to the practitioner skilled in the art. What is disclosed was chosen and described in order to best explain the principles and practical application of the embodiments described herein, thereby enabling others skilled in the art to understand the various embodiments and various modifications that are suited to the particular use contemplated. It is intended that the scope of what is disclosed be defined by the following claims and their equivalence.
Claims
1-19. (canceled)
20. A method of laterally inserting an intervertebral implant, comprising:
- accessing adjacent upper and lower vertebral bodies through a lateral approach;
- preparing the adjacent upper and lower vertebral bodies to receive an implant; and
- laterally inserting the implant between the adjacent upper and lower vertebral bodies, wherein laterally inserting comprises: mating an upper end plate of the implant with the upper vertebral body; and mating a lower end plate of the implant with the lower vertebral body, orienting a crossbar spacer between the upper and lower end plates, the crossbar spacer having a first spacer beam and a second spacer beam perpendicular to the first spacer beam, the first and second spacer beams being circular in cross-section, wherein the crossbar spacer facilitates movement of the first end plate and the second endplate relative to each other when implanted.
21. The method of claim 20, wherein preparing includes cutting receiving channels into the upper and lower vertebral bodies, and wherein laterally inserting the implant includes inserting a first keel of the upper end plate of the implant into the receiving channel of the upper vertebral body and a second keel of the lower end plate of the implant into the receiving channel of the lower vertebral body.
22. The method of claim 21, wherein laterally inserting includes orienting the first and second keels perpendicular to the sagittal plane of the vertebral body.
23. The method of claim 20, wherein the first spacer beam is off-set from the second spacer beam.
24. The method of claim 23, wherein the off-set between the first and second spacer beams allows the upper and lower end plates to pivot about the first and second spacer beams of the crossbar spacer.
25. The method of claim 23, wherein the off-set between the first and second spacer beams allow the spacer to be positioned between, and in contact with, the upper end plate and the lower end plate at the same time.
26. The method of claim 20, wherein the upper end plate includes a first inner surface with a first channel and the lower end plate includes a second inner surface with a second channel, wherein orienting the crossbar spacer includes receiving the first spacer beam in the first channel and receiving the second spacer beam in the second channel.
27. The method of claim 20, further comprising assembling the implant including:
- providing the upper implant member having a first inner surface with a first channel;
- providing the lower implant member having a second inner surface with a second channel, the second inner surface opposing the first inner surface; and
- orienting the cross-bar spacer includes inserting the crossbar member between the upper and lower implant members, wherein the first spacer beam is received in the first channel and the second spacer beam is received in the second channel.
28. The method of claim 20, wherein the orienting the crossbar spacer between the upper and lower end plates occurs before mating the upper and lower end plates with the respective upper and lower vertebral bodies.
29. A method of inserting an intervertebral implant laterally in a spine comprising:
- preparing an affected area of the spine to receive the implant laterally; and
- laterally inserting an implant into the affected area, including: mating an upper end plate of the implant with the upper vertebral body, the upper end plate having a first inner surface with a first channel; and mating a lower end plate of the implant with the lower vertebral body, the lower end plate having a second inner surface with a second channel perpendicular to the first channel, the second inner surface opposing the first inner surface, orienting a crossbar spacer between the upper and lower end plates, wherein orienting the crossbar spacer includes: positioning a first spacer beam of the crossbar spacer in the first channel; positioning a second spacer beam of the crossbar spacer in the second channel, the first and second spacer beams being circular in cross-section, wherein the crossbar spacer is movable relative to the upper end plate and the lower end plate.
30. The method of claim 29, wherein preparing an affected area includes exposing the affected area of the spine through a lateral access and removing the affected disk.
31. The method of claim 29, wherein preparing an affected area includes cutting receiving channels into adjacent upper and lower vertebral bodies, and wherein laterally inserting the implant includes inserting a first keel of the upper end plate of the implant into the receiving channel of the upper vertebral body and a second keel of the lower end plate of the implant into the receiving channel of the lower vertebral body.
32. The method of claim 31, wherein laterally inserting the implant includes orienting the first and second keels perpendicular to the sagittal plane of the vertebral body.
33. The method of claim 29, wherein the first spacer beam is off-set from the second spacer beam.
34. The method of claim 33, wherein the off-set between the first and second spacer beams allow the upper and lower end plates to pivot about the first and second spacer beams of the crossbar spacer.
35. The method of claim 33, wherein the off-set between the first and second spacer beams allows the spacer to be positioned between, and in contact with, the upper end plate and the lower end plate at the same time.
36. The method of claim 29, wherein the orienting the crossbar spacer between the upper and lower end plates occurs before mating the upper and lower end plates with the respective upper and lower vertebral bodies.
37. A method of laterally implanting a device between upper and lower vertebral bodies in a spine, the method comprising:
- exposing an affected region of the spine laterally;
- removing an affected disk between the upper and lower vertebral bodies;
- cutting receiving channels into the upper and lower vertebral bodies;
- selecting an implant having: an upper end plate adapted to mate with the upper vertebral body, the upper end plate having a first keel extending from a first outer surface; a lower end plate adapted to mate with the lower body, the lower end plate having a second keel extending from a second outer surface; and a crossbar spacer positioned between the upper and lower end plates, the crossbar spacer having a first spacer beam and a second spacer beam perpendicular to the first spacer beam, the first and second spacer beams being circular in cross section, wherein the crossbar spacer facilitates pivotal movement of the first end plate and the second end plate relative to each other; and
- inserting the implant between the upper and lower vertebral bodies, wherein inserting the implant includes inserting the first keel into the receiving channel of the upper vertebral body and the second keel into the receiving channel of the lower vertebral body.
38. The method of claim 37, wherein the upper end plate includes a first inner surface with a first channel and the lower end plate includes a second inner surface with a second channel, wherein the first spacer beam is received in the first channel and the second spacer beam is received in the second channel.
39. The method of claim 37, wherein the first spacer beam is off-set from the second spacer beam.
40. The method of claim 39, the off-set between the first and second spacer beams allow the upper and lower end plates to pivot about the first and second spacer beams of the crossbar spacer.
41. The method of claim 37, wherein cutting receiving channels into the upper and lower vertebral bodies includes cutting the channels perpendicular to the sagittal plane of the vertebral body.
Type: Application
Filed: Dec 17, 2007
Publication Date: Jun 12, 2008
Inventors: James F. Zucherman (San Francisco, CA), Ken Y. Hsu (San Francisco, CA), Steven T. Mitchell (Pleasant Hill, CA)
Application Number: 11/958,165
International Classification: A61F 2/44 (20060101);