US20080021556A1

Movatterモバイル変換

Info

Publication number: US20080021556A1
Application number: US11/491,450
Authority: US
Inventors: Jason A. Edie
Original assignee: Warsaw Orthopedic Inc
Current assignee: Warsaw Orthopedic Inc
Priority date: 2006-07-21
Filing date: 2006-07-21
Publication date: 2008-01-24
Also published as: US20100114319A1; US8083800B2

Abstract

An implant for insertion between vertebral body endplates includes first and second end members, each with a respective endplate contact surface. The implant further includes a collapsible intermediate section disposed between the first and second end members and an inflatable member contained within the intermediate section. The intermediate section may be expandable upon the introduction of a substance into the inflatable member between a first size to space the first and second end members a first distance apart and a second enlarged size to space the first and second end members a second greater distance apart. The inflatable member may increase in size from a compressed size in which the inflatable member will pass through an opening in the intermediate section and an expanded size in which the inflatable member will not pass through the opening and is thereby captively retained within the intermediate section.

Description

BACKGROUND

Spinal implants are often used in the surgical treatment of spinal disorders such as degenerative disc disease, disc herniations, scoliosis or other curvature abnormalities, and fractures. Many different types of treatments are used, including the removal of one or more vertebral bodies and/or intervertebral disc tissue. In some cases, spinal fusion is indicated to inhibit relative motion between vertebral bodies. In other cases, dynamic implants are used to preserve motion between vertebral bodies. In yet other cases, relatively static implants that exhibit some degree of flexibility may be inserted between vertebral bodies.

Regardless of the type of treatment and the type of implant used, surgical implantation tends to be a difficult for several reasons. For instance, access to the affected area may be limited by other anatomy. Further, a surgeon must be mindful of the spinal cord and neighboring nerve system. The size of the implant may present an additional obstacle. In some cases, a surgeon may discover that an implanted device has an inappropriate size for a particular application, which may require removal of the implant and insertion of a different implant. This trial and error approach may increase the opportunity for injury and is certainly time-consuming. Expandable implants are becoming more prevalent as a response to some of these concerns. However, the expansion mechanism in these devices tends to be complex and large. Consequently, existing devices do not appear to address each of these issues in a manner that improves the ease with which the device may be surgically implanted.

SUMMARY

Illustrative embodiments disclosed herein are directed to an implant for insertion between vertebral body endplates. The implant may include first and second end members, each with a respective endplate contact surface. The implant may further include a collapsible intermediate section disposed between the first and second end members and an inflatable member contained within the intermediate section. The collapsible intermediate section may be flexible and may be implemented using, for example, a continuous threaded tether, multiple tethers, or a mesh member. The collapsible intermediate section may be compliant or semi-rigid and naturally assume a compressed, but expandable insertion height. The intermediate section may be expandable upon the introduction of a substance into the inflatable member between a first size to space the first and second end members a first distance apart and a second enlarged size to space the first and second end members a second greater distance apart. The inflatable member may increase in size from a compressed size in which the inflatable member will pass through an opening in the intermediate section and an expanded size in which the inflatable member will not pass through the opening and is thereby captively retained within the intermediate section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a vertebral implant according to one embodiment positioned between vertebral bodies;

FIG. 2 is a section view of the vertebral implant according to the section lines inFIG. 1;

FIG. 3 is a perspective view of an exploded vertebral implant assembly according to one embodiment;

FIGS. 4-6 illustrate a sequence of implantation steps to obtain a desired vertebral body spacing, each Figure depicting a lateral view of a vertebral implant according to one or more embodiments shown relative to vertebral bodies;

FIG. 7 is a side view of a vertebral implant assembly according to one embodiment;

FIG. 8 is a top view of a vertebral implant assembly according to one embodiment;

FIG. 9 is a perspective view of one embodiment of a vertebral implant; and

FIG. 10 is a side view of a vertebral implant assembly according to one embodiment.

DETAILED DESCRIPTION

The various embodiments disclosed herein are directed to vertebral implants that are characterized by at least one expandable portion. The expandable portion may be assume a compressed first state during installation of the implant and may be expanded once the implant is positioned within the body. Anexemplary implant10 for supporting vertebral bodies is illustrated inFIG. 1. In one embodiment, theimplant10 is a vertebrectomy or corpectomy cage assembly positionable within an intervertebral space to span one or more vertebral levels along the longitudinal axis of the spinal column. Although the illustrated embodiment of theimplant10 spans one vertebral level, it should be understood that theimplant10 may be configured to span multiple vertebral levels.

FIGS. 1-3 illustrate that theimplant10 generally includes afirst end member22, asecond end member24, and one or moreexpandable portions26 between the first and

second end members

22,24. In one embodiment, the

end members

22,24 are formed of a biocompatible material, such as, for example, a carbon fiber material, or non-metallic substances, including polymers or copolymers made from materials such as PEEK and UHMWPE. In further embodiments, the

end members

22,24 may be formed of other suitable materials, such as, for example, stainless steel, titanium, cobalt-chrome, and shape memory alloys or other biocompatible metals.

The

end members

22,24 are adapted to engage the endplates of upper and lower vertebral bodies V1, V2. Theexpandable portion26 is engaged between the

end members

22,24 to maintain an intervertebral axial space S between the upper and lower vertebral bodies V1, V2 following the removal of one or more vertebral levels (shown in phantom inFIG. 1). Generally, theexpandable portion26 includes acollapsible portion41 and aninflatable portion35. In the embodiment shown, thecollapsible portion41 includes a series of cords ortethers42 and theinflatable portion35 includes a balloon-like structure36. A plurality oftethers42 may extend around theperimeter52 of the end members to form a cage. To facilitate insertion of theimplant10, theexpandable portion26 may be collapsed relative to the extended state shown inFIG. 1. Further details regarding process steps for insertion of theimplant10 are provided below.

Theexpandable portion26 is expandable in a direction that is substantially transverse to the

bone contact surfaces

32,34 of the

end members

22,24. The

bone contact surfaces

32,34 of the

end members

22,24 may be planar or define surface features and/or a number ofanchor elements80 adapted for engagement with the vertebral endplates to inhibit movement of the

end members

22,24 relative to the vertebral bodies V1, V2. For example, in one embodiment, the

bone contact surfaces

32,34 may be roughened, such as, for example, by knurling and/or etching (e.g., photochemical etching). In other embodiments, various types of projections or protrusions may extend from the

bone contact surfaces

32,34, such as, for example, a number of spikes, ridges, teeth, axial grooves, checkerboard-type grooves, or any other type of anchoringelement80 that would occur to one of skill in the art. Although the

bone contact surfaces

32,34 of the

end members

22,24 are illustrated inFIGS. 1 and 3 as being arranged substantially planar, it should be understood that the

bone contact surfaces

32,34 may be tapered or curved to more closely conform with the anatomical curvature of the vertebral bodies V1, V2 at the surgical site.

In one or more embodiments, theimplant10 may be expanded through the introduction of an injectable substance that fills an inflatable balloon-like member36, thereby causing the

end members

22,24 to move opposite one another. Thenumber90 inFIG. 2 identifies the injectable substance, which fills the balloon-like member36. In the embodiment shown, the balloon-like member36 includes a size and shape to fit within the

end members

22,24. Further, the balloon-like member36 includes a compressed size (see dimension B) that is small enough to fit between adjacent tethers42 (see dimension T) and an expanded size that is larger than the spacing betweenadjacent tethers42. Accordingly, the expanded balloon-like member36 is captively retained between the

end members

22,24 and inside thetethers42.

The

end members

22,24 include similar shapes, which permits the

end members

22,24 to fit the vertebral bodies V1, V2 in a similar manner. The

end members

22,24 generally include respective

bone contact surfaces

32,34 and anopposing surface54 facing opposite the bone-

contact surfaces

32,34, and aperipheral wall52 extending therebetween. In the illustrated embodiment, the

end members

22,24 include a kidney shape, though other shapes may be used. In further embodiments, the

end members

22,24 may take on other types of configurations, such as, for example, a circular shape, semi-oval shape, bean-shape, D-shape, elliptical-shape, egg-shape, or any other shape that would occur to one of skill in the art. In other embodiments, the

end members

22,24 could also be described as being annular, U-shaped, C-shaped, V-shaped, horseshoe-shaped, semi-circular shaped, semi-oval shaped, or other similar terms defining an implant including at least a partially open or hollow construction. Thus,

end members

22,24 may be constructed for use in a variety of procedures, including but not limited to those requiring an anterior approach, a lateral approach, a posterior approach, or a trans-foraminal approach.

It should further be appreciated that the size and/or configuration of the

end members

22,24 may be specifically designed to accommodate any particular region of the spinal column and/or any particular vertebral level. For example, in embodiments associated with the upper thoracic or cervical region of the spine, the

end members

22,24 may be designed to have a D-shaped configuration, whereas embodiments associated with the lumbar region of the spine may be configured to have a horseshoe-shape, a U-shape, or other types of open-sided configurations.

In one embodiment, the

end members

22,24 have an outer profile that is substantially complementary to the size and shape of the peripheral portion or outlying region of the vertebral bodies V1, V2, such as the cortical rim or the apophyseal ring of the vertebral endplates. For example, as illustrated inFIG. 2, the outer perimeter of theend member24 is preferably disposed generally above the inner edge of the cortical rim R of the vertebral body V1. In this manner, at least a portion of the

end members

22,24 is engaged against the cortical region of the vertebral endplates, thereby minimizing the likelihood of subsidence into the relatively softer cancellous region of the vertebral bodies V1, V2 following insertion of theimplant10 within the intervertebral space S.

Additionally, each of the bone contact surfaces32,34 may include one or more apertures or recesses50 formed by aninner surface82. Therecess50 is open at the bone contact surfaces32,34 and provided to enhance bony fusion between the

end members

22,24 and vertebral bodies V1, V2. Therecesses50 may be blind holes in that they do not extend through the

end members

22,24. Therecesses50 may be through-holes in that they do extend through the

end members

22,24. In one or more implementations, theimplant10 may be inserted in conjunction with bone growth materials that may include, for example, bone graft, bone morphogenetic protein (BMP), allograft, autograft, and various types of cement, growth factors and mineralization proteins. In a further embodiment, the bone growth promoting materials may be provided in a carrier (not shown), such as, for example, a sponge, a block, a cage, folded sheets, or paste. The bone growth materials may be loaded into theapertures50 or generally applied to the bone-

contact surfaces

32,34.

Thetethers42 may be constructed of a complaint biocompatible material, such as a resin or polymer that may include materials such as nylon, polyethylene, polyurethane, silicone, polyethylene, polypropylene, polyimide, polyamide, and polyehteretherketone (PEEK). Further, thetethers42 may be constructed of a wide variety of woven or nonwoven fibers, fabrics, metal mesh such as woven or braided wires, polymeric fibers, ceramic fibers, and carbon fibers. Biocompatible fabrics or sheet material such as ePTFE and Dacron®, Spectra®, and Kevlar® may also be used. Thetethers42 may be cable-like, with a circular cross section or tape-like with a flattened cross section. Other cross sections may be possible or desirable, including for example, triangular, rectangular, polygonal, elliptical, or other cross sections. Furthermore, thetethers42 may be secured to one or both of the

end members

22,24 using a variety of methods, including for example, tying, adhering, welding, or other methods that would occur to one skilled in the art.

Thetethers42 may be compliant in that they assume a shape that is determined by the spacing between the

end members

22,24. That is, thetethers42 may be similar to a rope or thread and assume a random shape when the

end members

22,24 are brought in proximity to one another. In one embodiment, thetethers42 are semi-rigid in that they assume a particular bent, curved, or splined shape to maintain a compressed height between the

end members

22,24. However, as the

end members

22,24 are pushed apart, such as by inflating the balloon-like structure36, thetethers42 will straighten to allow the

end members

22,24 to separate. Those skilled in the art will comprehend that a semi-rigid characteristic may be obtained through the use of flexible resin or composite materials or through the use of a thin metal filament, rod, or spring (not explicitly shown).

The balloon-like structure36 may be constructed of a complaint biocompatible material, such as a resin or polymer that may include materials such as nylon, polyethylene, polyurethane, silicone, polyethylene, polypropylene, polyimide, polyamide, and polyehteretherketone (PEEK). The balloon-like structure36 may be formed from materials that are used in other conventionally known biomedical applications, such as balloon angioplasty. Further, the balloon-like structure36 may be reinforced with concentric layers of similar or dissimilar materials and/or fabrics (not specifically shown). For instance, a reinforcing structure may be constructed of a wide variety of woven or nonwoven fibers, fabrics, metal mesh such as woven or braided wires, polymeric fibers, ceramic fibers, and carbon fibers. Biocompatible fabrics or sheet material such as ePTFE and Dacron®, Spectra®, and Kevlar® may also be used. Furthermore, the balloon-like structure36 may be a separate member or may be secured to one or both of the

end members

22,24.

In one embodiment, the balloon-like structure36 includes permeable end surfaces39. That is, the end surfaces39 include a perforated, grated, or mesh-like structure that allows theinjectable substance90 to pass from within the balloon-like structure36 and through theapertures50 to contact the corresponding vertebral bodies V1, V2 (see e.g.,FIG. 1). In one embodiment, most or all of the balloon-like structure36 is permeable in a similar manner. In one embodiment, no portion of the balloon-like structure is permeable (i.e., the injectable substance is substantially contained therein). The permeable nature of at least the end surfaces39 makes it advantageous to include bone growth promoting materials within theinjectable substance90. Accordingly, as theinjectable substance90 is inserted into the balloon-like structure36, the

end members

22,24 will expand under the influence of the expanding balloon-like structure36. Additionally, some of theinjectable substance90 will exit the permeable end surfaced39 and enter theapertures50. Consequently, growth-promoting materials contained therein are positioned to enhance bone growth from adjacent vertebral bodies V1, V2 into theimplant10. In one embodiment, the permeable end surfaces39 may be configured to contain theinjectable substance90 until a certain internal pressure is obtained. Beyond that pressure, obtained through introducing additionalinjectable substance90, theinjectable substance90 will exit the end surfaces39 and enter theapertures50.

Various techniques may be used to introduce aninjectable substance90 into the balloon-like structure36. In the embodiment shown, afill port52 is provided on the balloon-like structure36. Notably, while only onefill port52 is depicted,additional ports52 may be used. Further, theport52 may be located in different locations depending on a particular implementation and angle of approach. Thefill port52 may be attached to a syringe or other pumping mechanism (seeFIGS. 4-6) to fill the balloon-like structure36. An injectable substance may flow through thefill port52 into the interior volume of the balloon-like structure36. As the injectable substance fills the balloon-like structure36, the ends39 of the balloon-like structure36 extend to contact the

end members

22,24 and may expand to fill therecesses50 formed within the

end members

22,24. As the ends39 of the balloon-like structure36 expand, they exert a displacement force F that causes the

end members

22,24 to separate from one another. Furthermore, fillport52 may include a self-sealing valve (not specifically shown) that prevents the injectable substance from flowing in one direction or another once the balloon-like structure36 is filled.

A variety of injectable substances may be inserted into the balloon-like structure36 to cause the

end members

22,24 to separate. In one embodiment, the injectable substance is a fluid, such as a gas or a liquid. In one embodiment, the injectable substance is a solid, such as a powder. In one embodiment, the injectable substance is a curable liquid that solidifies after a predetermined amount of time or under the influence of an external catalyst. For instance, an injectable liquid may cure under the influence of heat or light, including ultraviolet light. Some examples of in situ curable liquids include epoxy, PMMA, polyurethane, and silicone. A curable substance may cure to a substantially rigid state or to a flexible, but relatively incompressible state.

Theimplant10 may be inserted into a patient according to the process steps illustrated inFIGS. 4-6. InFIG. 4, theimplant10 is inserted in a compressed first state including a first height H1 and positioned within an intervertebral space formed after the removal of one or more vertebrae or discs. Once theimplant10 is positioned as shown inFIG. 4, theinflation tool100 or other injection instrument is used to position the balloon-like structure36 and inject the injectable substance into thefill port52 on the balloon-like structure36. As suggested above, the balloon-like structure36 is collapsed and is able to fit between

end members

22,24 through the spacing T1 betweentethers42. Note that in the collapsed first state with a height H1, thetethers42 may be compliant and may be separated to insert the balloon-like member36.

In one embodiment, asingle tool100 is used to position and fill the balloon-like structure. In one embodiment, the balloon-like structure is positioned between the

end members

22,24 using a different tool (not shown) than theinflation tool100. In one embodiment, the balloon-like member36 is pre-positioned between the

end members

22,24 and inserted into the intervertebral space along with the

end members

22,24.

Theinflation tool100 may be implemented as a syringe-like structure including areservoir portion102 and adelivery portion104. Thedelivery portion104 is configured to engage thefill port52 to transfer the injectable substance from thereservoir portion102 into the balloon-like structure36. Other delivery mechanisms are certainly appropriate. For instance, pneumatic or hydraulic fittings may be appropriate. Thedelivery portion104 may be implemented as a needle, as tubing, or other cannulated devices. In any event, as the injectable substance is introduced into theimplant10, the

end members

22,24 are forced apart due to the expansion of the contained balloon-like structure36. Ultimately, theimplant10 is expanded to an expanded second state including a second height H2 as shown inFIG. 6. In the expanded second state with a height H2, thetethers42 may pulled somewhat taught and the spacing T2 between adjacent tethers is sufficiently maintained to captively retain the balloon-like member36.

FIG. 7 depicts a top (or bottom) view of an

exemplary end member

22A or24A for use in thevertebral implant10. In previous embodiments, the

end members

22,24 included anopen recess50. In the embodiment illustrated inFIG. 7, therecess50 is covered by apermeable member60 that provides a physical barrier to expansion by the balloon-like structure but that permits fluid flow and bony ingrowth. Thepermeable member60 may be constructed of a braided or mesh-like biocompatible material, such as a resin or polymer that may include materials such as nylon, polyethylene, polyurethane, silicone, polyethylene, polypropylene, polyimide, polyamide, and polyehteretherketone (PEEK). Further, the permablemember60 may be reinforced with layers of similar or dissimilar materials and/or fabrics (not specifically shown). For instance, a reinforcing structure may be constructed of a wide variety of woven or nonwoven fibers, fabrics, metal mesh such as woven or braided wires, polymeric fibers, ceramic fibers, and carbon fibers. Biocompatible fabrics or sheet material such as ePTFE and Dacron®, Spectra®, and Kevlar® may also be used.

In embodiments described above, theexpandable portion26 included acollapsible portion41 comprised of a series of cords or tethers42. In the embodiment shown inFIG. 8, thecollapsible portion41 includes a mesh-like member142 that is secured to end

members

22B,24B. The mesh-like member142 is generally compliant and may be collapsed and extended to permit theoverall implant10B to assume compressed and extended heights H1, H2 as shown inFIGS. 4 and 6. The mesh-like member142 may be constructed from materials disclosed herein or using a variety of other biocompatible materials known to those skilled in the art. The mesh-like member142 is provided with anopening144 through which the balloon-like member36 may be inserted. As with the previously-describedtethers42, theopening144 is advantageously sized to permit a collapsed balloon-like member36 to pass, but small enough to prevent an inflated balloon-like member36 from escaping.

FIG. 9 depicts an embodiment of animplant10C similar to the embodiments depicted inFIGS. 1-3. However, in the present embodiment, thetether42A is provided as a continuous member that is threaded through and between the

illustrated end members

22C,24C. Note that thesingle tether42A is threaded through the

end members

22C,24C withindividual runs43 of thetether42A functioning as theseparate tethers42 in above-described embodiments. The illustratedtether42A may be implemented as a continuous member, passing throughtether holes200 and at least partially passing throughtether channels202 in the

end members

22C,24C. Notably, thechannels202 may be recessed below the bone-

contact surfaces

32C,34C to allow the bone-

contact surfaces

32C,34C to directly contact the corresponding endplates on the vertebral bodies. The ends of thetether142 may be secured to each other using a variety of methods, including for example, tying, adhering, crimping, soldering, welding, or other methods that would occur to one skilled in the art.

FIG. 10 depicts an embodiment of animplant10D in which thecollapsible portion41 includes sliding and

telescoping attachment members

170,172, respectively. In one embodiment, the

attachment members

170,172 are rigid and capable of axially sliding relative to one another according to the arrows labeled M. Further, because the

attachment members

170,172 are rigid, the

end members

22D,24D are maintained in a predetermined alignment relative to each other. In one embodiment,

attachment members

170,172 are flexible members that are capable of axially sliding relative to one another as well as lateral bending. Consequently, the

end members

22D,24D remain coupled, but are movable relative to each other in multiple directions.

In certain implementations, where the injectable substance remains fluid or takes an extended period of time to cure, the

end members

22D,24D are provided with

position locks

156,158. In one embodiment,attachment member172 includes protruding features156 andattachment member170 includes recessedfeatures158 disposed at various heights about the interior thereof. Thus, when the

attachment members

170,172 are joined to one another, the protruding features156 engage the recessed features158 to provide a locked height that prevents compression of theimplant10D. That is, as the balloon-like structure36 is filled with an injectable substance, the

end members

22D,24D will separate and expand to a position where aprotrusion156 engages arecess158. At this point, introducing additional injectable substance will force theprotrusion156 to disengage from therecess158 and ultimately engage a nexthigher recess158. Theprotrusions156 and/or therecesses158 may be angled, tapered, or oriented to permit expansion of theimplant10D but not compression in the reverse direction. Those skilled in the art will comprehend a variety of ways to implement this type of unidirectional locking. The protruding features156 may be implemented using a variety of features, including but not limited to ball plungers, expanding pegs, protruding stops, and shape-memory alloys. In the latter case, the protruding features156 may be positioned in a first retracted position and then, upon the application of elevated temperatures (which may be provided by body temperatures), the protrudingfeature156 will expand to engage arecess158 corresponding to a desired implant height.

Spatially relative terms such as “under”, “below”, “lower”, “over”, “upper”, and the like, are used for ease of description to explain the positioning of one element relative to a second element. 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.

As used herein, the terms “having”, “containing”, “including”, “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”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.

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. For instance, the embodiments disclosed herein have contemplated a single implant positioned between vertebral bodies V1, V2. In other embodiments, two or more smaller implants may be inserted between the vertebral bodies V1, V2. 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

1. An implant for insertion between vertebral body endplates in a patient, the implant comprising:

a first end member including a first endplate contact surface;

a second end member including a second endplate contact surface;

a collapsible intermediate section disposed between the first and second end members; and

an inflatable member contained within the intermediate section,

the intermediate section being expandable upon the introduction of a substance into the inflatable member, the intermediate section being expandable between a first size to space the first and second end members a first distance apart and a second enlarged size to space the first and second end members a second greater distance apart.

2. The implant ofclaim 1 wherein the collapsible intermediate section is flexible.

3. The implant ofclaim 1 wherein the collapsible intermediate section comprises a plurality of tethers secured about a perimeter of the first and second end members.

4. The implant ofclaim 1 wherein the collapsible intermediate section comprises a single tether coupled between a perimeter of the first and second end members.

5. The implant ofclaim 4 wherein the single tether is coupled to the first and second end members with the tether disposed beneath the first and second endplate contact surfaces.

6. The implant ofclaim 1 wherein the collapsible intermediate section comprises a mesh member secured about a perimeter of the first and second end members.

7. The implant ofclaim 1 wherein the collapsible intermediate section maintains the first size to space the first and second end members the first distance apart when the inflatable member is not expanded through the introduction of the substance.

8. The implant ofclaim 1 wherein the collapsible intermediate section comprises attachment members slidably engaged to permit movement of the end members in an expansion direction, the attachment members including position locks at predetermined heights to stabilize the implant.

9. An implant for insertion between vertebral body endplates in a patient, the implant comprising:

a first end member including a first endplate contact surface;

a second end member including a second endplate contact surface;

a collapsible intermediate section disposed between the first and second end members, the intermediate section including an opening; and

an interior member positionable within the intermediate section, the interior member inflatable between a compressed size in which the interior member will pass through the opening and an expanded size in which the interior member will not pass through the opening.

10. The implant ofclaim 9 wherein the collapsible intermediate section is flexible.

11. The implant ofclaim 9 wherein the collapsible intermediate section comprises a plurality of tethers secured about a perimeter of the first and second end members, the distance between adjacent tethers forming the opening.

12. The implant ofclaim 9 wherein the collapsible intermediate section comprises a single tether coupled between a perimeter of the first and second end members in a plurality of runs, the distance between adjacent runs forming the opening.

13. The implant ofclaim 12 wherein the single tether is coupled to the first and second end members with the tether disposed beneath the first and second endplate contact surfaces.

14. The implant ofclaim 9 wherein the collapsible intermediate section comprises a mesh member secured about a perimeter of the first and second end members.

15. The implant ofclaim 9 wherein when the interior member is at the compressed size, the first and second end members are a first distance apart and when the interior member is at the expanded size, the first and second end members are a second greater distance apart.

16. The implant ofclaim 15 wherein the collapsible intermediate section maintains the first and second end members the first distance apart when the interior member is at the compressed size.

17. The implant ofclaim 9 wherein the collapsible intermediate section comprises attachment members slidably engaged to permit movement of the end members in an expansion direction, the attachment members including position locks at predetermined heights to stabilize the implant.

18. A method of supporting vertebral bodies, the method comprising the steps of:

positioning an implant between endplates of the vertebral members while the implant is in a first orientation having a first height;

inserting an inflatable member through an opening in the implant;

introducing a substance into the inflatable member;

inflating the inflatable member to an expanded size in which the inflatable member is captively retained within the implant; and

separating first and second end members and increasing a height of the implant.

19. The method ofclaim 18 wherein the substance includes a bone growth promoting substance.

20. The method ofclaim 18 wherein the step of separating first and second end members and increasing a height of the implant comprises forcing a bone-contact surface of the first and second end members into contact with the endplates of the vertebral members.

21. The method ofclaim 18 wherein the step of separating first and second end members and increasing a height of the implant comprises extending a collapsible intermediate section that is coupled between the end members.

22. The method ofclaim 18 wherein the step of separating first and second end members and increasing a height of the implant comprises extending a tether that is coupled between the end members.

23. A method of supporting vertebral members, the method comprising the steps of:

coupling first and second end members with a collapsible intermediate section;

positioning an inflatable member within the collapsible intermediate section;

inserting an amount of a substance into the inflatable member;

filling the inflatable member with the substance and causing the inflatable member to contact faces of the first and second end members;

exerting an expansion force at the faces and expanding the collapsible intermediate section and separating the first and second end members to an increased height; and

further expanding the first and second members into contact with the vertebral members.

24. The method ofclaim 23 wherein the substance includes a bone growth promoting substance.

25. The method ofclaim 23 wherein prior to filling the inflatable member with the substance and causing the inflatable member to contact faces of the first and second end members, the inflatable member is sized to pass through an opening in the collapsible intermediate section.

26. The method ofclaim 23 wherein the step of exerting an expansion force at the faces and expanding the collapsible intermediate section comprises extending a tether that is coupled between the first and second end members.