WO2007090017A1

WO2007090017A1 - Intervertebral implants and methods of use

Info

Publication number: WO2007090017A1
Application number: PCT/US2007/060980
Authority: WO
Inventors: Hai H. Trieu
Original assignee: Warsaw Orthopedic, Inc.
Priority date: 2006-01-27
Filing date: 2007-01-24
Publication date: 2007-08-09
Also published as: US7578849B2; CN101404958A; AU2007211121A1; US20070191953A1; EP1981444A1; KR20080093138A

Abstract

Implants and methods for spacing and stabilizing vertebral members. The implant in one embodiment may include first and second endplates (11, 12) and an intermediate section (13) that form an interior section (14) . An elastic member (20) may be positioned within the interior section to space apart the endplates. The elastic member may have a variety of orientations, sizes, shapes, densities, modulus of elasticity, and other material properties depending upon the desired displacement between the first and second endplates. In use according to one embodiment, the implant may assume a first shape when the vertebral members are aligned, such as when the patient is standing erect or in a prone position. This first shape may include the first and second endplates spaced a first distance apart. During movement of the vertebral members, the endplates may be forced together. The intermediate section in combination with the elastic member may be deformed during this movement and thereby exert a force to stabilize the vertebral members.

Description

INTERVERTEBRAL IMPLANTS AND METHODS OF USE-

Background

The present application is directed to devices and methods for stabilizing vertebral members, and more particularly, to intervertebral implants and methods of use for replacing an intervertebral disc, vertebral member, or combination of both to distract and/or stabilize the spine.

The spine is divided into four regions comprising the cervical, thoracic, ϊumbsr, and sacrococcygeal regions. 'Hie cervical region includes the fop seven vertebral members identified as C1-C7. The thoracic region includes the next twelve vertebral members identified as T1-TΪ2. The lumbar region includes five vertebral members L 1-L5. The sacrococcygeal region includes nine fused vertebra! members that form the sacrum and the coccyx. The vertebral members of the spine are aligned in a curved configuration that includes- a cervical curve, thoracic curve, and lumbosacral curve. Intervertebral discs are positioned between the vertebral members and permit flexion, extension, lateral bending_., and .rotation.

Various conditions may lead to damage of the intervertebral discs and/or the vertebral members. The damage may result from a variety of causes Including a specific event such as trauma, a degenerative condition, a tumor, or infection. Damage to the intervertebral discs and vertebral members can lead to pain, neurological deficit, and/or loss of motion.

Various procedures include replacing the entirety or a section of a vertebral member, the entirety or a section of an intervertebral disc, or both. One or more replacement implants may be inserted to replace the damaged vertebral members and/or discs. The implants reduce or eliminate the pain and neurological deficit, and increase the range of motion. Summary

The present application is directed to implants and methods for spacing and stabilizing vertebral members. The implant may include first and second endplates and art intermediate section that form an interior section. An elastic member may be positioned within the interior section to space apart the endplates. The elastic member may have a variety of orientations, sizes, shapes, densities, modulus of elasticity, and other materia! properties depending upon the desired displacement between the first and second endplates. in use according to one embodiment, the implant, may assume a first shape when the vertebral members are aligned, such as when the patient is standing erect or in a prone position, This first shape may include the first and second endplates spaced a. first distance apart. During movement of the vertebral members_., the endplates may be forced together or apart. The intermediate section in combination with the elastic member may be deformed during this movement and thereby exert a force to stabilize the vertebra! members.

Brief Description of the Drawings

Figure 1 Is a perspective view of ati implant according to one embodiment.

Figure 2- is a cross-sectional view of an implant positioned between vertebral members according to one embodiment.

Figure 3 is a cross-sectional view of an implant positioned between vertebral members that are in flexion according to one embodiment.

Figure 4 is a perspective view of a body having upper and lower endplates and an intermediate section according to one embodiment.

Figure 5 is a side schematic view of a body according to one embodiment.

Figures 6A-F are side schematic views of embodiments of a body with an Intermediate section.

Figure 7 is a side schematic view of a body according to one embodiment.

Figures 8A-8H are cross-sectional top views of embodiments of an elastic member positioned relative to an end plate.

Figures 9A-9D are side schematic views of embodiments of elastic members positioned within a body. Figure 10 is a cross-sectional view of an elastic member according to one embodiment- Figure 1 1. is a cross-sectional view of an elastic member according to one embodiment. Figure 12 is a schematic side view of a Hmiter according to one embodiment. Figures 13A-13B are side schematic views of a limiter according to onz embodiment. Figures 14A-C are views of an implant according to one embodiment. Figure 15 is a cross-sectional top view of devices positioned relative to a vertebral member according to one embodiment.

Detailed Description

The present application is directed to implants, and methods for replacing an intervertebral disc, vertebral member, or combination of both. The implant, includes a body sized to replace the removed elements. The body may include first and second endplates and an intermediate section that together form an interior section. An elastic member is positioned within the interior section. The elastic member may have a variety of orientations, sizes, shapes, densities, modulus of elasticity, and other material properties depending upon the desired displacement between the first and second endplates. The endplates may be spaced apart a first distance when the vertebral members are aligned. During movement of the vertebral members, the endplates may be forced together or apart. The intermediate section in combination with the elastic member may be deformed during this movement and thereby exert a force that prevents or reduces the movement of the endplates.

Figure 1 illustrates one embodiment of an implant having a body 10, Body 1.0 includes an upper endplate 1 !., lower en dpi ate 12, and an intermediate section 13. Intermediate section 13 spaces apart the endplates 1 1, 12 forming an interior section 14. An elastic member 20 is positioned within the interior section 14. Tabs 30 may extend from the body 10 and provide a means for positioning the body 10 relative to the vertebral members 100.

Figure 2 illustrates a cross-sectional view of the implant of Figure i positioned within the patient. The implant is in a first position with the vertebral members 100 being substantially aligned. The upper and lower endplates 1 1, 12 are in contact with vertebral members 100. Intermediate section 13 is positioned within the space formed between the vertebral members 100. In this embodiment, intermediate section 13 is positioned in a posterior direction in proximity with a posterior edge 102 of the vertebral members and away from a.n anterior edge 103. Elastic member 20 is positioned within the interior section 14. Tabs 30 extend into the vertebral members J00 to position the implant.

Figure 3 illustrates the implant with the vertebral members 100 in flexion. The movement of the vertebral .members 100 causes the endpiates 11, 12 to move inward towards one another and plastically deform the elastic member 20 and the intermediate section 13. The intermediate section 13 arid the elastic member 20 resist, the flexion and apply an outward force on the vertebra! members ^"100. The amount of force applied to the vertebral members ! 00 may vary as described below in detail. Both the intermediate section Vi and elastic member 20 may be constructed of elastic, resilient materials that return towards their original shape upon realignment of the vertebra! members 100.

In one embodiment the intermediate section 13 and the elastic member 20 are flexible to provide dynamic- stabilization while maintaining certain biomechanics! motions of the spine. Stabilization may be .maintained during motions such as flexion, extension, lateral bending, and rotation. The intermediate section .13 and elastic member 20 are constructed to have a predetermined stiffness to provide the stabilization. Further, the stiffness may vary during a biomechanical motion.

Body .10 comprises the upper and lower endpiates 1 1 , 12 and the intermediate section 13. In one embodiment such as illustrated in Figure f , the body 10 is constructed of a single member having a folded configuration, ϊn other embodiment, body 10 is constructed of two or more different members. Figure 5 illustrates one embodiment with the intermediate section 13 constructed of a separate piece that is attached to the endpiates ϊ 1 j 12. Upper endplate 11 is attached to the member 1 S with one or more fasteners 16.

Embodiments of fasteners 16 may include rivets, pins, screws, etc. Lower endplate 12 is attached to the member I S in another manner, such as with adhesives, welding, brazing, etc. Figure 7 illustrates another embodiment with the intermediate section 13 constructed of two separate members 18a, ISb. IΛ tins embodiment, first member 1 Sa .is integral with endplate i.ϊ, and second member I Sb is integral with endpiate 12. Members 1.8a, 1.8b are connected together in a manner as described above. Body 10 may be constructed of a. variety of materials including metals, polymers, ceramics, and combinations thereof. Examples of metals include έitanium, titanium alloys such as nickel-titanium, stainless steel, and cobalt chromium. Examples of polymers include PEEK, PEEK-carbon composites, poiyimide, polyeiherimkle, and polyurethane. Examples of ceramics include calcium, phosphate, hydroxyapatϊte. HAPCP, alumina, and zirconium.

EmIpI ales .1 1 , 12 are shaped to contact, the vertebral members 100. Endplates I 1 _> .12 may be shaped to adapt accurately to the shape of the plates of the vertebral .members 100. The shape and size of the endplates I L 12 may vary, as well as the size of the surface area that contacts the vertebral members 100. One embodiment illustrated in Figures HA-C includes convex endplates U, 12. The upper and lower endplates I L 12 may have the same shape and size, or may have different shapes or sizes. By way of example, the embodiment of Figure i includes endplates 1 1, YX having substantially the same shape and size. In other embodiments, endplates I L 12 may have different shapes and sizes. Examples of shapes for the endplates 11, 11 include round, oval, elliptical, kidney shaped, square, rectangular, trapezoidal, and boomerang shape, etc.

One embodiment illustrated in Figure 4 includes the upper endplate 1 1. with a split configuration having first and second lingers 1 Ia, 1 Ib₅ with the lower endplate 1.2 formed as a single section and having an opening 15. In one embodiment, the space formed between the fingers 1.1a, J. Ib and the opening 1 S are aligned. In one embodiment, endplates 1 1, 12 have a planar eon struct? on as illustrated in the embodiments of Figure 4, 6 A, and 6B, ϊn another embodiment, endplates I L 12 have a curved coHstajetion as illustrated in. the embodiments of Figures 6C₃ and 6F. In yet other embodiments, endplates I L 12 have a combination of curved and planar sections as illustrated in the embodiment ofFigure βD.

Endplates U, 12 may be positioned at a variety of relative angular positions when no external forces are applied to the implant, In one embodiment, endplates 1 1, 12 are substantially parallel, ϊn another embodiment, the endplates Ll, i2 angle outward from the intermediate section 13 such that a height of the interior section 13 is less near the intermediate section .13 and increases towards the ends of the endplates I L .12. hi another embodiment, endplates 1 1, 1.2 angle inward as they extend from the intermediate section 13.

Intermediate section 13 extends between the endplates 1 1, 12 and provides resistance to movement of the endplates Ll , 12. Intermediate section 13 may have a variety of shapes, ϊn one embodiment as illustrated in Figure 5, intermediate section 13 has substantially planar upper and lower sections. In. other embodiments, intermediate section 13 has a curved shape, In various other embodiments, intermediate section 1.3 has a combination of planar and curved shapes. The width of the intermediate section 13 may be substantially the same or different as one or both eπdpiates .1 1 , 12. In one embodiment, illustrated in Figures 14A-C, the width of the intermediate section 13 is less than the end plates 1 I, 12. The narrower width may be centered along a centerline of the body 10, or may be off-center. The thickness of the intermediate section 13 may be the same or different as one or both endplaies 1.1, 12. Ia one embodiment, intermediate section 13 comprises two separate spaced-apart sections as illustrated in Figure 8H.

In some embodiments, intermediate section 13 is constructed from a single member 18. Figure όA illustrates owe embodiment with the intermediate section 13 having a curved shape with an overlapping configuration between the endplates 1 1, 12. Figure 6B illustrates an embodiment having an intermediate section 13 with an overlapping configuration and comprised of planar and curved sections. Figure 6C illustrates an embodiment having multiple overlapping sections. Figure 6D illustrates an embodiment with an intermediate section 13 having an enclosed section 17 positioned between sections of member 18.

Embodiments of the intermediate section 13 may include multiple members .1 S. Figure 6E illustrates an embodiment with a curved first support section. 18a and a second support section 1 Sb. Figure 6F illustrates another embodiment of an intermediate section 13 comprising sections 18a, 18b, and 18c. Section .18a extends from the endplates 1.1, Ϊ2. Sections ISb, 1 Sc form a criss-cross pattern. In embodiments having multiple members Iδ, members IS may be constructed hi a unitary fashion, or from multiple different members fastened together. Members IS may extend along the entire width of the endplates I L .12, or a limited section or sections of the width, lύ the embodiment of Figure 4, the endplate 18 extends along substantially the entire width. Jn the embodiment of Figure 14C₅ the member 18 extends along a limited width of the endpiaies .1.1 , 12.

Further, the body may include multiple members IS as illustrated. in the embodiments of Figures SF and SH. In embodiments with multiple members 1.8, the members may have the same construction, or may have different constructions.

Elastic member 20 is positioned within the interior space 14 and has a stiffness to provide resistance and prevent .movement of the eadplates ϊ .1 _> 12. The elastic member 20 shares the load applied to the implant and may prevent fatigue failure of the intermediate section 13. The elastic member 20 may impose a substantially linear or non-linear resistance to prevent movement of the endplates 1.1, 12.

Elastic member 20 may be constructed of a variety of different, materials. Member 20 may be resilient, and change shape during movement of the endplates .1 , 12. Examples of such materials include elastic or rubbery polymers, hydrogels or other hydrøphUie polymers, or composites thereof. Particularly suitable elastomers include silicone, polyurethane, copolymers of silicone and polyurethane, polyolefms, such as polyisobutylene and polyisoprene, neoprene, nilrile_r vulcanized rubber and combinations thereof. Examples of polyurethanes include thermoplastic polyurethanes, aliphatic polyurethanes, segmented polyurethanes, hydrophilic polyuretlianes, polyether~urethaiie_s polyc&rbonate-urethane and silicone pofyethemrethane. Other suitable hydrophilic polymers include polyvinyl alcohol hydrogel, polyacryl amide hydrogel , poϊyacrylic hydrogel, poiy(N~vmyl-2-pyrrolidQne hydrogel, polyhydroxy ethyl methacryϊate hydrogel, and naturally occurring materials such as collagen and polysaccharides, each as hyaluronic acid and cross- linked carboxyl-cøntaining polysaccharides, and combinations thereof. Elastic member 20 may be connected to the body 10, or may be freely positioned within the interior section. 14, In one embodiment, elastic member 20 is connected to one or more of the endplates I L 12 and intermediate section 13. The elastic member 20 may be connected with mechanical fasteners such as screws, pins, rivets, etc. ϊn another embodiment, elastic member 20 is connected to the body 10 with an adhesive, ϊn one embodiment, the inner edges of one or more of the endplates 11, 12 and intermediate section 13 include a roughened surface, ridges, teeth,, etc. to maintain the position of the elastic member 20, ϊn one embodiment, the elastic member 20 is shaped to connected with one or both endplates 11, 12. In a specific embodiment, the elastic member 20 has a dovetailed recess that mounts to an extension that extends from the endplate.

When connected to both emlplates 1 1, 12, the elastic member 20 provides resistance to both inward and. outward movement, During inward movement of the endplates J. I₁ 12, elastic member 20 is compressed and provides a resistance to the inward movement. During outward movement of the endplates Fl , 12, the elastic member 20 is placed in tension to provide resistance, ϊ∑i one embodiment, the elastic member 20 is placed in compression during flexion of the vertebral members and placed in tension during extension.

In one embodiment with the elastic member 20 connected to only one endplate 1 I or 12, or when positioned between the endplates 1.1, 12 and connected to neither, the elastic member 20 provides resistance to inward movement The elastic tnember 20.may not be placed in tension during outward movement and the resistance to this movement is limited to the intermediate section 13.

Elastic member 20 may be spaced from or in contact with the intermediate section 13. Elastic member 20 may further have a variety of heights and widths. In various embodiments, elastic member 20 is constructed from a single member as illustrated in

Figures 8A-SE. Figure SA illustrates one embodiment having an elastic member 20 with a substantially rectangular shape. Figure SB illustrates a substantially €-shaped elastic member 20 with the base facing an anted or direction away from the support member IS of the intermediate section 13. Figure SC illustrates an elastic member 20 having a rectangular first surface that contacts the eπdplate 12 and four planar sidewalis that taper upwards. Figure 8D illustrates an embodiment having an irregular, nonsymmetrical shape. Figure SE illustrates an embodiment having a substantially C-shaped elastic member 20 with a base facing in a posterior direction towards the support member IS of the intermediate section 13.

Elastic member 20 may further include two or more separate .members. The separate members may have the same construction, or may be constructed of different materials having a different, stiffness. Figure SF illustrates an embodiment having three separate elastic members 20a, 20b, 20c. Each, elastic member 20a, 2Ob₅ 20c is independent and positioned within the interior section 14 and has a substantially rectangular shape,

Figure SG illustrates another embodiment having elastic members 20a. 20b_? 20c each having a circular cross-sectional shape. Figure SH illustrates an embodiment having a first elastic member 20a that is positioned within a second elastic .member 20b. In one embodiment, elastic members 20a, 20b are connected together. In embodiments as illustrated in Figures SG and 8H, elastic members 20 may have cylindrical, spherical,, or conical shapes.

In a non-deformed state, the elastic member 20 may have a variety of heights B. In one embodiment, the height is sized for the member 20 to extend between and contact both endplates 1 1, 12. hi one embodiment, the height H may be substantially the same throughout the elastic member 20. Ln other embodiments as illustrated in Figures 9 A and 9β, the height H may vary along the elastic member 20. In one embodiment, elastic member 20 has a first height H when the vertebral members are aligned. When placed in compression, the elastic member 20 has a smaller height. When placed in tension, the elastic member 20 stretches and has a greater height.

Figure 9 A includes elastic member 20 having a height that decreases away from the intermediate section 13, &nά Figure 9B includes the elastic member 20 having a height the increases away from the intermediate section 13.

The implant may provide a variable resistance to deformation. The variable resistance may cause less resistance to initial amounts of vertebral movement, but apply greater forces to reduce larger vertebral movements. By way of example, the Implant may be designed to provide little resistance during an initial amount of movement of the endpiates 1 1 , 12. Larger amounts of resistance may he applied to the vertebral members when the endpiates 1 1 _> 1.2 move beyond the initial amount, In some embodiments, the stiffness of the elastic member 20 and intermediate section 13 increases with additional amounts of movement. The amount of resistance applied by one or both members may increase the further they move away from the original, first position.

Variable resistance may also result during compression from the height of the elastic member 20. ϊn one embodiment, the height of the elastic member 20 is less than the height of the interior section (i.e., the member 20 does not contact both endpiates .1 1, 12), The resistance to the initial inward movement of the endpiates 1 1. 12 is isolated to the intermediate section 13. The elastic member 20 does not affect the stiffness until it is contacted by both endpiates J i, 12 and begins to deform, In one embodiment, deformation is limited to the intermediate section 1.3 during an amount: of initial endpiate movement. Movement beyond this initial amount causes the endpiates 1 1, 12 to begin deforming the elastic member 20 in addition to continued deformation of the intermediate section 13 resulting in greater stiffness of the implant and more resistance to additional movement.

The .shape of the elastic member 20 may further cause variable resistance to deformation. Greater amounts of contact between the endpiates 1 1, ^'12 and the elastic- member 20 may result in greater amounts of resistance. By way of example using the IO embodiments of Figures 9A and 9B₅ the peaked shapes of the elastic members 20 provides less resistance during initial amounts of inward movement of the endplates 1 1, 12. Additional inward movement of the endplates 11, 12 results in deformation of larger amounts of the elastic member 20 resulting it? greater resistance.

^'Variable resistance may also be provided by multiple elastic elements. Figure 9C illustrates an embodiment having two separate elastic members 20a and.20b. During inward movement of the endplates 11, 12, the inner elastic member 20a is initially contacted thus causing a first amount of resistance. The second elastic member 20b is not contacted by the endplate 13 until the endplates 1.1, 12 are compressed beyond a predetermined amount. This compression then causes the elastic member 20b to deform resulting in additional amounts of resistance, In this embodiment., elastic members 20a, 20b may have the same or different stiffnesses.

Figure 9D illustrates an embodiment having a single elastic member 20 constructed of first and second materials 28a, 2Sb having a different stiffness. MtIa! compression of the endplates .1 1 , 12 causes deformation of the first material 28a. resulting in a first resistance. Additional compression causes deformation of the first and second materials 28a_; 28b which together provide additional resistance.

In. another embodiment {.not. illustrated), first and second members 20a, 20b are each attached to both endplates 11 , 12. In this embodiment, the first member 20a has a greater height than tbe second member 20b. During initial outward movement of the endplates I L l 2, the second member 20b is placed in tension before the first member 20a. After a predetermined amount of outward movement, the first member 20a is also placed in. tension thus increasing the overall resistance to movement of tbe endpiates IJ₅ 1.2. Elastic member 20 may fill varying amounts of the interior section 14. As illustrated in the embodiments of Figure 2, member 20 fills a limited amount, of the interior section 14. Tn another embodiment as illustrated in Figures 10 and 11, elastic members 20 substantially fill the entirety of die interior section .14. in the embodiments of Figures 10 and .1 1 , voids 2i are positioned within the elastic member 20, In one embodiment, voids have a specific shape and size to control the supporting abilities of tbe elastic member 20. Voids 21 may be substantially free of material, or may be filled with a material that is different than that, of the elastic member 20, As illustrated in Figure 10, voids 2.1 may be I i positioned within the interior of the elastic member 20, or may be positioned along one edge as illustrated m Figure 1.1.

In one embodiment, elastic member 20 is positioned completely within the interior section 14. In other embodiments, elastic member 20 is positioned within the interior section 14 and extends outward from one or more sides.

A. linύter may prevent movement of the endplates 1 1 , 1.2 beyond a predetermined amount. Figure 12 illustrates one embodiment having a. rigid limiting .member 75 positioned within the interior section ^"14. Inward movement of the endplates 1 ?., 12 will cause deformation of the elastic member .20. At a predetermined amount of movement, a top edge of limiting member 75 contacts the endplate 1 1 and prevents further inward movement. limiting member 75 may have a variety of different shapes and orientations.

In another embodiment, limiting member 75 is formed of a non-elastic member that is attached to both endpiates 1 1, 12. The limiting member 75 is in a slackened condition during an initial orientation as a length of the member 75 is greater than the distance between the endplates 1 1, 12. After trie endplates 1.1, 12 have moved outward a predetermined distance, the limiting member 75 is tightened and limits further outward movement.

Another limiting embodiment is illustrated in Figures 13 A. and 13B. Endplates 1 1, 12 are formed with ends 19 positioned opposite from the intermediate section 13. In a first position as illustrated in Figure 13 A, ends 19 are spaced apart. This allows for inward movement of the endplates 11, 12 during vertebral movement. At a predetermined amount of inward movement, ends 19 contact together as illustrated in Figure I.3B and further inward movement is prevented.

∑n one embodiment, a keel extends outward from, one or both endplates 11, 12 to connect with the vertebral members 100. In one embodiment as illustrated in Figure 2. tabs 30 are positioned within the vertebral members 100. In another embodiment, tabs 30 are positioned along an outer edge of the vertebral members 100 with the interior section 14 and intermediate section 13 positioned between the vertebral members 100, Tabs 30 may include apertures for receiving fasteners to attach the implant to the vertebral members 100.

In one embodiment, one or both endplates I i. J2 are constructed to have increased contact with the vertebral members. ϊ.n one embodiment, the endpiates 11, 12 are constructed of a porous material. Jn another embodiment, endplates 1 1, 12 are textured. ΪJO stiπ other embodiments, endplates 1 L .12.include spikes or serrations. In. one embodiment, one or both endplates ^"1.1, 1.2 may be coated with osteo-oαnductive material. Embodiments of the material may include hydroxy&patile and BMP.

Vertebral movement may cause relative movement of the endplates .11 , 12. The terms "inward movement", "outward movmenf and the like are used herein in a general sense to describe the general motion of the endplates 1 1 , 12 that reduces or increases the distance between the endplates 1 1,, 12. The endplates 1 1, 12 may move directly towards or away from one another during this movement or there may be some lateral component to the movement. Further, the vertebral movement may cause movement of one or both of the endplates .1 .1 , 12.

The device can be placed within, the intervertebral space by a variety of different approaches including anterior and lateral approaches. In one embodiment the device is inserted through a posterior approach.

In one embodiment_s multiple devices are inserted within the intervertebral space as il lustrated in Figure 15. In this embodiment, the devices may be placed bi laterally with the intervertebral space relative to the vertebral member 200.

In another embodiment, a single device i$ inserted for the correction of scoliosis. In this embodiment, the device may be placed on the concaved side of the spinal column to Increase the disc height on the lower side.

In one embodiment, the elastic member 20 is positioned within the interior section 14 prior to placing the implant into the intervertebral space, ϊn another embodiment; the body 10 is initially placed within the intervertebral space and then the elastic member 20 is positioned within the Interior section 14,

As used herein, the terms "having", "containing", "including'¹, "comprising" and the like are open ended terms that indicate the presence of stated elements or features, but do not. preclude additional elements or features. The articles "a", "arr" and "the" are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.

Spatially relative terms such as "under", "below", "lower", "over", "upper", "lower", "intermediate", and the like, are used for ease of description to explain the relative positioning of elements. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as "first", "second", and the like, are also used to describe various elements, regions, sections., etc and are also not intended to be limiting. Like terms refer to like elements throughout the description.

The present invention may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. In one embodiment, the implant replaces ail or a part of a disc. In another embodiment, implant replaces all or part of a disc and all. or part of one or more vertebral members. Intermediate section 13 may have the same width as the endplat.es 11, 12, or may have different widths. Intermediate section 13 may also have the same or different thickness as the endpl&tes .1.1 , 12. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

Claims

What is claimed Is:

L An intervertebral device positioned between vertebral members, the device comprising: an elongated member having an overlapping configuration with art intermediate section that spaces apart first and second endplates; and an elastic member positioned between the first and second endplates and. proximate to the intermediate section, the elastic member sized to space apart the first and second endplates during movement of the vertebral members,

2. The device of claim 1 , wherein the first endplate has a different shape than the second endplate.

3. The device of claim 2, wherein the first endplate comprises first and second spaced- apart fingers.

4. The device of claim 1, wherein the intermediate section and the first and second endplates form a substantially C-shape.

5. The device of claim I , wherein the intermediate section has an overlapping shape,

6. The device of claim 5, wherein the intermediate section comprises first and second support, members.

7. The device of claim 1, wherein the elastic member is spaced away from the intermediate seed on.

8. The device of claim 1 , further comprising a second elastic member positioned between the first and second endplates, the second elastic member being spaced away from the elastic member.

9. TBe device of claim S, wherein the second elastic member has a different stiffness than the elastic member.

10. The device of claim 8, wherein the second elastic member has a different height than the elastic member.

1 1. The device of claim )._r further comprising a limiting member positioned between the first and second endplates, the limiting member being constructed to limit movement of the first and second endpiates beyond a predetermined amount,

12. The device of claim 1, wherein the elastic member has a length measured between a first edge and a second edge, a height of the elastic member being variable along the length.

13. An intervertebral device positioned between vertebral members, the device comprising: an elastic member; a first endpϊate positioned above the elastic member and a second en dpi ate positioned below the elastic member; and an intermediate member positioned at ends of the first and second endplates a.«d connecting together the first and second endplates, the intermediate member and the elastic member being configured to maintain the first and second endplates in a spaced apart configuration.

14. The device of claim 13, wherein the first and second endplates at least partially overlap.

15. The device of claim 13, wherein the first and second endplates and the intermediate member extend around three sides of the elastic member.

16. The device of claim 13, wherein the intermediate member has an overlapping configuration.

17. The device of claim 16, wherein a first section of the intermediate member is substantially planar and a second section of the intermediate member is substantially curved.

.1 S. The device of claim 13, wherein the .first, endplate is connected to the intermediate section.

19. The device of claim 18, further comprising connecting means for connecting together the first, endplate &nά the intermediate section.

20. The device of claim 13, wherein the first and second endplates and the intermediate section are constructed from a single, elongated member.

21. An intervertebral device positioned between vertebral members, the device comprising: a flexible body having a width and positioned in an overlapping configuration to define a. three-sided cavity; and an elastic .member positioned within the cavity and sized to space apart first and second sections of the flexible body.

22. The device of claim 2.1, wherein the flexible body includes an intermediate section having an overlapping configuration, the intermediate section spacing apart the first and second sections.

23. The device of claim 22, further comprising a second elastic member positioned within the cavity.

24. The device of claim 21, further comprising a limiter positioned within the cavity, the Ii miter being constructed to prevent first and second endplates of the flexible body from moving beyond a predetermined limit.

25. The device of claim 21 , wherein a height of the elastic member varies along tine length of the elastic member,

26. An intervertebral device positioned between vertebral members_* the device comprising: an elastic member; a first endplate positioned above the elastic member and a second en dpi ate positioned below the elastic member; and. ars intermediate member integral with the first and second endplaSes and positioned at ends of the first and second endplates, the intermediate member and the elastic member being deformable to apply a. force to the first and second endplat.es during movement of the vertebral members.

27. The device of claim 26, wherein the elastic member extends outward beyond the first and second endplates.

28. The device of claim 26, further comprising a second elastic member positioned between the endplates, the second elastic member having a different stiffness than the elastic member.

29. The device of claim 26, wherein the elastic member has a variable height.

30, An Intervertebral device positioned between vertebral members, the device comprising: an elongated member having a folded orientation forming first and second endpiates and an intermediate section; an elastic .member positioned between the first and second endplates, the elastic member having a stiffness to apply an outward force so the first and second endplates when the first and second etidpiates move inward beyond a predetermined amount.