US20190209337A1 - Articulating spacer - Google Patents

Abstract

Spinal implants are disclosed. One spinal implant includes a support body, an articulating element, a blocking member and a motion limiting member. The support body includes a superior end surface and a lower end surface having teeth. In between the superior end surface and the lower end surface is a recess formed in a sidewall of the support body for receiving the articulating element. The blocking member can be received in the recess to prevent inadvertent back-out of the articulating element from within the recess. The articulating element can articulate in one or more directions, thereby allowing articulation of the spinal implant into a desired position within a disc space.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This patent application is a continuation of U.S. patent application Ser. No. 15/619,604, filed Jun. 12, 2017, which is a continuation of U.S. patent application Ser. No. 14/992,328, filed Jan. 11, 2016, now U.S. Pat. No. 9,700,428, which is a continuation application of U.S. patent application Ser. No. 14/011,317, filed on Aug. 27, 2013, now U.S. Pat. No. 9,259,327, which is a continuation application of U.S. patent application Ser. No. 13/109,754, filed on May 17, 2011, now U.S. Pat. No. 8,545,566, which is a continuation-in-part application claiming priority to U.S. patent application Ser. No. 12/250,168, filed on Oct. 13, 2008, now U.S. Pat. No. 8,147,554, each of which are hereby incorporated by reference in their entireties for all purposes.
FIELD OF THE INVENTION
• The present application generally relates to intervertebral spacers, and in particular, to articulating intervertebral spacers.
BACKGROUND OF THE INVENTION
• The vertebrate spine is the axis of the skeleton providing structural support for the other parts of the body. Adjacent vertebrae of the spine are supported by an intervertebral disc, which serves as a mechanical cushion permitting controlled motion between vertebral segments of the axial skeleton. The intervertebral disc is a unique structure comprised of three components: the nucleus pulposus (“nucleus”), the annulus fibrosus (“annulus”) and two vertebral end plates.
• The spinal disc can be displaced or damaged due to trauma, disease, degenerative defects or wear over an extended period of time. For example, disc herniation occurs when annulus fibers are weakened or torn and the inner tissue of the nucleus becomes permanently bulged. The mass of a herniated or “slipped” nucleus tissue can compress a spinal nerve, resulting in leg pain, loss of muscle control, or even paralysis. In addition, in some cases, a degenerated nucleus can lose its water binding ability and deflate, thereby reducing the height of the nucleus and causing the annulus to buckle in certain areas.
• To alleviate back pain caused by disc herniation or degeneration, the disc can be removed and replaced by an implant that promotes fusion of the remaining bone anatomy. The implant, such as a spacer or cage body, should be sufficiently strong to support the spine under a wide range of loading conditions. The implant should also be configured so that it is likely to remain in place once it has been positioned in the spine by the surgeon. In addition, the implant should be capable of being delivered minimally invasively or at least through a relatively small incision into a desired position.
• Thus, there remains a need for an improved implant that addresses these difficulties.
SUMMARY OF THE INVENTION
• Various embodiments of spinal implants are provided. In one embodiment, a spinal implant comprises a support body having a superior end surface and an inferior end surface, wherein each of the superior end surface and the inferior end surface include one or more teeth. The spinal implant includes a side recess formed in the support body in between the superior end surface and the inferior end surface for receiving an articulating element therethrough. In addition, the spinal implant includes an articulating element positioned in the recess, wherein the articulating element is configured to rotate along one or more axes.
• In another embodiment, a spinal implant comprises a support body having a superior end surface and an inferior end surface. The spinal implant includes a side recess formed in the support body in between the superior end surface and the inferior end surface for receiving an articulating element therethrough. The spinal implant further includes an articulating element sized for insertion through the recess and configured to rotate along one or more axes, as well as a blocking member configured to be positioned within the recess for preventing back-out of the articulating element from within the recess.
• In another embodiment, a spinal implant comprises a support body having a superior end surface and an inferior end surface, wherein each of the superior end surface and the inferior end surface includes one or more teeth, and wherein the support body includes a proximal end portion and a distal end portion having a tapered surface. A longitudinal opening can be formed through the support body, wherein the longitudinal opening is configured to receive a bone graft material. A side recess is formed in the support body between the superior end surface and the inferior end surface. The implant further comprises an articulating element sized and shaped to be received in the recess, the articulating element including an aperture with threads for receiving a portion of an insertion tool and a groove on a top portion thereof. A blocking member can be insertable through an aperture in the support body. The blocking member can be configured to prevent unintentional back-out of the articulating element from within the recess of the support body. In addition, a motion limiting member can be insertable through an aperture in the support body. The motion limiting member can be configured to contact the groove of the articulating element and to prevent over-articulation of the articulating element within the recess of the support body.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective exploded view of an implant according to some embodiments.
• FIG. 2A is a perspective exploded view of an alternative implant having an articulating element with a bumper element according to some embodiments.
• FIG. 2B is a top view of the articulating element of the implant inFIG. 2A.
• FIG. 2C is a side perspective view of the articulating element of the implant inFIG. 2A.
• FIG. 2D is a cross-sectional view of the implant inFIG. 2A.
• FIG. 3A is a perspective exploded view of an alternative implant having a support body with a substantially flat side surface according to some embodiments.
• FIG. 3B is a top view of the implant inFIG. 3A.
• FIG. 3C is a top view of an articulating element of the implant inFIG. 3A.
• FIG. 3D is a side perspective view of the articulating element of the implant inFIG. 3A.
• FIG. 4 is a perspective exploded view of an alternative implant having an articulating element with a substantially spherical body according to some embodiments.
• FIG. 5A is a perspective exploded view of an alternative implant having a combined blocking element and motion limiting element according to some embodiments.
• FIG. 5B is a side perspective view of an articulating element of the implant inFIG. 5A.
• FIG. 5C is a different side perspective view of the articulating element of the implant inFIG. 5A.
• FIG. 5D is a cross-sectional view of the articulating element of the implant inFIG. 5A.
• FIG. 6 is a perspective exploded view of an alternative implant having a support body with a built-in bumper element according to some embodiments.
• FIG. 7 is a perspective exploded view of an alternative implant having an articulating element configured to receive a retaining pin according to some embodiments.
• FIGS. 8A-8D illustrate a method of inserting an implant in a disc space using a delivery instrument according to some embodiments.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
• Detailed embodiments of the invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.
• The present application generally relates to implants such as intervertebral spacers, and in particular, to articulating intervertebral spacers. The implants can be used to fuse together a treated area of the spine while restoring or maintaining the proper spacing and natural curvature of the spine. The treated area can include regions between adjacent vertebral bodies so that the height of the implant corresponds approximately to the height of the disc. Advantageously, the improved implants described herein are configured to articulate with ease into a desired position in between two vertebrae. In some embodiments, the improved implants can articulate along multiple axes, thereby providing greater flexibility when positioning the spacer is a desired location. Novel features of the implants allow for more efficient insertion or placement of the implants into a desired position in between vertebrae.
• FIG. 1 is a perspective exploded view of a spacer implant according to some embodiments. Theimplant10, which is configured to fit into a disc space in between two vertebrae, comprises asupport body14, an articulatingelement40, a blockingmember60, and amotion limiting member70.
• Thesupport body14 of theimplant10 includes asuperior end surface35 for contacting a superior vertebra and aninferior end surface37 for contacting an inferior vertebra. On the superior and/or inferior end surfaces are one ormore teeth24 designed to contact the adjacent vertebrae and keep thesupport body14 in a desired position. Also formed within the superior and/or inferior end surfaces are one or morelongitudinal openings21. The one or morelongitudinal openings21 can be formed through partly or completely through theimplant10, and are configured to receive bone graft or other natural and/or synthetic material to facilitate bone growth when implanted. In addition, on the superior and/or inferior end surfaces are one or more apertures—aperture64 for receiving a blockingmember60 andaperture68 for receiving amotion limiting member70, which are discussed in more detail below.
• In addition, thesupport body14 includes aproximal end portion16 and adistal end portion18. As shown inFIG. 1, thedistal end portion18 can have a taperedsurface20. In alternative embodiments, theproximal end portion16 can have a tapered surface instead of or in addition to the distal end portion. In some embodiments, when placing asupport body14 in between vertebrae, thedistal end portion18 with the taperedsurface20 can serve as the leading portion that is positioned in a disc space. Advantageously, the taperedsurface20 assists in self-distraction of vertebral bodies when thesupport body14 is inserted in between vertebrae.
• As shown inFIG. 1, thesupport body14 also includes a side cut-out section orrecess22 formed on a curved sidewall of thesupport body14. Therecess22 defines a space that is configured to receive an articulatingelement40 therein. Compared to other spacer implants, in which articulating elements may be implanted through a portion of thesuperior end surface35 and/orinferior end surface37, thesupport body14 of the present application advantageously provides a side entrance for the articulatingelement40, thereby reducing the need to machine an aperture through theteeth24. This advantageously preserves the number of teeth and/or surface area covered by teeth and increases the ability of the spacer to remain secure within a disc space.
• During use, the articulatingelement40 of theimplant10 can remain in therecess22 of theimplant10. The articulatingelement40 advantageously allows thesupport body14 to be rotated in one or more axes (as shown inFIGS. 8A-8D), thereby allowing thesupport body14 to be in a proper orientation and location within a disc space. To prevent the articulatingelement40 from falling out of theimplant10, a blockingmember60 can be provided, as discussed further below.
• The articulatingelement40 comprises anaperture42, a pair of substantiallyflat surfaces45 and agroove47 that extends along an upper portion of the articulatingelement40. When the articulatingelement40 is positioned within therecess22 of thesupport body14, the substantiallyflat surfaces45 face inner walls of thesupport body14. In between the substantiallyflat surfaces45 of the articulatingelement40 is anaperture42 for receiving a mateable portion of a delivery instrument100 (as shown inFIGS. 8A-8D). In some embodiments, when the mateable portion of thedelivery instrument100 is attached to the articulatingelement40, the articulatingelement40 allows thesupport body14 to articulate or rotate relative to an axis of the delivery instrument, thereby allowing thesupport body14 to be placed in a desired position in a disc space, as shown inFIGS. 8A-8D. In some embodiments, theaperture42 of the articulatingelement40 includes a plurality of internal threads (not shown) that mate with external threads of a portion of a delivery instrument. Advantageously, the articulatingelement40 can articulate along one or more axes that extend across theaperture42 when the articulatingelement40 is positioned within thesupport body14.
• In some embodiments, theaperture42 extends completely through a diameter of articulatingelement40. In other embodiments, theaperture42 extends through only a portion of a diameter of the articulatingelement40. In some embodiments, the articulatingelement40 comprises twoseparate apertures42 that are formed on opposite sides of the articulatingelement40.
• A recess orgroove47 is formed along a portion of a top surface of the articulatingelement47. Thegroove47 is configured to contact amotion limiting member70 that is received through theaperture68. With themotion limiting member70 in thegroove47, the articulatingelement40 can articulate, but will be prevented from over-articulating or over-rotating such that theaperture42 will remain visible through theside recess22 during a surgical procedure. In other words, themotion limiting member70 helps to prevent the articulatingelement40 from over-articulating to such a degree that theaperture42 faces the inside of thesupport body14 whereby it would be unable to receive a mateable portion of adelivery instrument100. Advantageously, while themotion limiting member70 is in contact with thegroove47, the articulatingelement40 can articulate through any angle up until themotion limiting member70 contacts theend surface49 of the groove (shown inFIG. 1). As shown inFIG. 1, themotion limiting member70 can be a small cylindrical stump or peg that contacts thegroove47 of the articulating element, although it is not limited to this particular shape or size. For example, themotion limiting member70 can be square or rectangular in shape.
• To prevent the articulatingelement40 from inadvertent back-out or removal from thesupport body14, a blockingmember60 can be placed throughaperture64 to block and secure the articulatingelement40 within thesupport body14. The blockingmember60 can be inserted through anaperture64 formed in therecess22 of thesupport body14. As shown in the illustrated embodiment, the blockingmember60 can comprise a cylindrical peg, although it is not limited to this shape or size. For example, in some embodiments, rather than be cylindrical in shape, the blockingmember60 can be rectangular in shape.
• FIG. 2A is a perspective exploded view of an alternative implant having an articulating element with a bumper element according to some embodiments. Like the prior illustrated embodiment, theimplant10 includes asupport body14 having aside recess22 for receiving an articulatingelement40, an articulatingelement40 including anaperture42, and a blockingmember60 to prevent inadvertent back-out of the articulating element from the support body. However, in the present embodiment, the articulatingelement40 includes a bumper element84 (shown inFIGS. 2B and 2C) that prevents over-articulation or over-rotation of the articulatingelement40 instead of a separatemotion limiting member70. Before the articulatingelement40 is over-articulated or over-rotated, thebumper element84 can contact an inner wall25 within thesupport body14 to prevent over-articulation. In some embodiments, thebumper element84 sits in a groove or track88 (shown inFIG. 2D) that allows for limited articulation, thereby advantageously preventing over-articulation.
• FIGS. 2B and 2C illustrate abumper element84 positioned on a surface of the articulatingelement40. In some embodiments, thebumper element84 comprises a protruding feature that extends from the surface of the articulatingelement40. As shown inFIG. 2C, thebumper element84 can be positioned near or adjacent theaperture42. In other embodiments, thebumper element84 can be positioned in other locations, such as away from theaperture42 in other locations along the circumference of the articulating element. While the articulatingelement40 in the illustrated embodiment includes asingle bumper element84, in other embodiments, the articulatingelement40 includes two ormore bumper elements84. For example, an articulatingelement40 can include twoseparate bumper elements84, one on each side of theaperture42, thereby preventing over-articulation or over-rotation in one or more directions. Furthermore, in some embodiments, the articulatingelement40 can include abumper element84, yet still work in conjunction with amotion limiting member70 as shown inFIG. 1.
• FIG. 3A is a perspective exploded view of an alternative implant having a support body with a substantially flat side surface according to some embodiments. While the illustrated embodiment inFIG. 1 includes animplant10 having asupport body14 with arecess22 formed in a curved sidewall, theimplant10 inFIG. 3A includes arecess22 formed in a sidewall that is substantially flat along at least a portion of the sidewall. The substantially flat portion of thesidewall15 is visible in the top view inFIG. 3B. With the substantially flat portion of thesidewall15, thesupport body14 inFIG. 3A assumes less of a sickle-shape relative to the embodiment inFIG. 1. Advantageously, a surgeon can choose to use animplant10 with a support body having a curved sidewall and sickle-shaped body as inFIG. 1, or animplant10 with a support body having a substantially flat sidewall as inFIG. 3A, thereby providing greater options for the surgeon to address different body shapes. The different shape of the support body inFIG. 3A provides a different axial footprint that can cover a greater surface area compared to the support body inFIG. 1. In addition, the different shape also provides a larger graft opening.
• As shown inFIGS. 3C and 3D, theimplant10 can include an articulatingelement40 having abumper element84 as discussed above. Thebumper element84 can advantageously help to prevent over-articulation or over-rotation of the articulatingelement40 within thesupport body14 having the substantially flat sidewall.
• FIG. 4 is a perspective exploded view of an alternative implant having an articulatingelement44 with a substantiallyspherical body49 according to some embodiments. The articulatingelement44 inFIG. 4 has a more spherical shape with a rounder surface relative to the articulatingelement40 inFIG. 1. Advantageously, the substantially spherical body of the articulatingelement44 inFIG. 4 provides for increased articulation along one or more axes of rotation, thereby providing more flexibility in the placement of thesupport body14 within a disc space. For example, in some embodiments, the articulatingelement44 can move along a generally horizontal axis, as well as along other axes that intersect the horizontal axis. Like the articulatingelement40 inFIG. 1, the articulatingelement44 inFIG. 4 can be positioned in a recessedportion22 formed within thesupport body14.
• FIG. 5A is a perspective exploded view of analternative implant10 having a combined blocking andmotion limiting element63 according to some embodiments. Like the illustrated implant inFIG. 1, thealternative implant10 ofFIG. 5A includes asupport body14 including aside recess22 and an articulatingelement40. In contrast, however, thealternative implant10 includes a combined blocking andmotion limiting element63 that functions to prevent both the inadvertent back-out of the articulatingelement40 and over-articulation of the articulatingelement40.
• As shown inFIG. 5A, the combined blocking andmotion limiting element63 includes a blockingpost67 that transitions into amotion limiting feature69. The blockingpost67 helps to prevent the inadvertent back-out of the articulatingmember40 from within thesupport body14. Themotion limiting feature69, which is configured as an extension from the blockingpost67, can rest on thegroove47 to prevent over-articulation and/or over-rotation of the articulatingelement40. The combined blocking andmotion limiting element63 can be delivered through anaperture65 formed through a superior and/or inferior surface of thesupport body14, as shown inFIG. 5A. Theaperture65 can be of a different size and shape compared toapertures64 and68 (inFIG. 1) to accommodate the features of the combined blocking andmotion limiting element63.
• In addition, the articulatingelement44 inFIG. 5A includes distinct features from the previously described articulating elements. In particular, in addition to having a substantially spherical body that advantageously provides for multi-axis articulation, the alternative articulatingelement44 also includes a top bump-out feature61 and a bottom bump-out feature62 (shown inFIG. 5D). When the articulatingelement44 is received in the recessedportion22 of thesupport body14, the top bump-out feature61 and the bottom bump-out feature62 can be received in one or more channels orgrooves27 formed within thesupport body14. Thegrooves27 advantageously allow for some rotation of the articulatingelement44 along the longitudinal axis of the grooves, thereby providing articulation in multiple directions. In addition, the grooves help to limit the amount of rotation along the longitudinal axis of the grooves, thereby helping to prevent over-articulation in that rotational direction.
• FIGS. 5B-5D more clearly illustrate the specific features of the articulatingelement44, including the top bump-out feature61 and the bottom bump-out feature62. Of particular note is the cross-sectional view inFIG. 5D, in which it is shown that the shape of the articulating element44 (including the top bump-out feature61 and the bottom bump-out feature62) generally conforms to a sphere, thereby allowing for maximum possible articulation and rotation within thesupport body14.
• FIG. 6 is a perspective exploded view of analternative implant10 having asupport body14 with a built-inbumper element71 according to some embodiments. The built-inbumper element71 can comprise a protruding surface that extends from an inner wall of thesupport body14. In some embodiments, the built-inbumper element71 helps to prevent inadvertent back-out of the articulatingelement40 in thesupport body14. As thebumper element71 is built-in to the body of thesupport body14, apertures for receiving a blocking member need not be formed through an end surface of thesupport body14, thereby advantageously increasing the number ofteeth24 and/or surface area of teeth for contacting a vertebral surface.
• FIG. 7 is a perspective exploded view of an alternative implant having an articulating element configured to receive a retaining pin according to some embodiments. The articulatingelement40 includes anaperture42 for receiving a portion of a delivery instrument, as well as an aperture or hole72 formed therein for receiving a blockingmember60. When the articulatingelement40 is positioned in thesupport body14 and the blockingmember60 is inserted therein, the blockingmember60 serves as an axis of rotation about which the articulating element rotates.
• Each of the novel implants described above provides an articulating element that can be articulated in one or more axes. In some embodiments, the articulating elements can be articulated between about 0 and 130 degrees, or between about 0 and 75 degrees along one or more axes.
• Once a spacer implant is moved into a desired position between vertebrae, it is desirable for the implant to have sufficient structural rigidity or integrity such that the implant does not buckle or otherwise fail under loading by the spine. The implant should be configured so that it can sustain both axial compression and shear forces, as well as torsional forces. In some embodiments, the rigidity of the implant exceeds the rigidity of neighboring vertebral bodies to ensure that the implant does not collapse or fail under loading conditions.
• The height of the spacer implant can vary depending upon the height of the area of the spine that is to be treated. In some embodiments, a variety of implants having different heights can be provided, thereby giving a surgeon multiple options of which implant to use. In other embodiments, the height of the implant can be adjusted within the disc space.
• Any biocompatible material can be used to form all or part of a spacer implant of the present application. Suitable materials can include, but are not limited to, titanium, stainless steel and/or other surgical grade metals and metal alloys. In addition, various polymers, such as polyetheretherketone (PEEK), can also be used to form at least part of the spacer implant.
Methods of Use
• The application encompasses a spacer implant having an articulating element that is loaded through a side cut-out section or recess of the spacer implant. The spacer implant can be implanted into a disc space between two vertebrae.
• Various instruments can be provided to deliver the spacer implant in between two vertebrae. For example, in some embodiments, a delivery instrument or insertion tool as described in U.S. patent application Ser. No. 12/250,168 to Hansell et al., filed on Oct. 13, 2008 and hereby incorporated by reference in its entirety, can be used to deliver the spacer implant. The delivery instrument is capable of rigidly attaching to implant10 and preventing rotation or articulation of theimplant10 with respect to the delivery instrument axis. When a surgeon desires to allow the implant to articulate with respect to the delivery instrument axis, a portion of theimplant10 can disengage from the delivery instrument to selectively allow the implant to articulate via an articulation element with respect to the delivery instrument axis. The implant can articulate to a desired position within a disc space, wherein it can be completely disengaged from the delivery instrument.
• With reference toFIGS. 8A-8D, in some embodiments, the application encompasses methods for implantation comprising:
• a. forming an incision in a patient;
• b. attaching a spacer implant to a delivery instrument, wherein the spacer implant includes a superior end surface with teeth, an inferior end surface with teeth, a side recess therebetween and an articulating element positioned within the side recess, wherein the spacer implant is rigidly attached and incapable of articulating with respect to the delivery instrument axis;
• c. delivering the delivery instrument and spacer implant through the incision to a disc space (FIG. 8A);
• d. disengaging a portion of the spacer implant from the delivery instrument, thereby allowing the spacer implant with side recess to articulate via the articulating element with respect to the delivery instrument axis (FIG. 8B);
• e. rotating the spacer implant via the articulating element relative to the delivery instrument until the spacer implant is in a desired position and orientation in a disc space (FIGS. 8C and 8D);
• f. maintaining attachment of the spacer implant to at least a portion of the delivery instrument until the spacer implant is in the desired position; and
• g. disengaging the spacer implant completely from the delivery instrument and leaving the spacer implant within the body of the patient.
• Any of thespacer implants10 having side recesses for receiving an articulating element as described with respect toFIGS. 1-7 can be used with the methods described herein.
• It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. Moreover, the improved spacer implants and related methods of use need not feature all of the objects, advantages, features and aspects discussed above. Thus, for example, those skilled in the art will recognize that the invention can be embodied or carried out in a manner that achieves or optimizes one advantage or a group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. In addition, while a number of variations of the invention have been shown and described in detail, other modifications and methods of use, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is contemplated that various combinations or subcombinations of these specific features and aspects of embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the discussed spacer implants. Thus, it is intended that the present invention cover the modifications and variations of this invention provided that they come within the scope of the appended claims or their equivalents.

Claims (20)

What is claimed is:

1. An articulating implant comprising:

a body having a proximal end portion and a distal end portion, first and second side surfaces that extend between the proximal end portion and the distal end portion, and upper and lower surfaces that extend between the proximal end portion and the distal end portion,

a recess formed in the proximal end portion;

an articulating element received in the recess, wherein the articulating element comprises an aperture for receiving a portion of a delivery instrument therein;

a blocking element extending through an opening in the upper surface and configured to prevent back-out of the articulating element from the recess; and

a separate motion limiting member received in a groove in the recess.

2. The implant ofclaim 1, wherein the motion limiting member is a cylindrical peg.

3. The implant ofclaim 1, wherein the motion limiting member is enlarged relative to the blocking element.

4. The implant ofclaim 1, wherein the blocking element is at least partially in the form of a cylindrical post.

5. The implant ofclaim 1, wherein the motion limiting member is configured to prevent over-rotation of the articulating element.

6. The implant ofclaim 1, wherein the blocking element extends through an opening in the lower surface of the implant.

7. The implant ofclaim 1, wherein the first side surface is convexly curved and the second side surface is concavely curved.

8. The implant ofclaim 1, wherein the distal end portion comprises a tapered surface.

9. The implant ofclaim 1, wherein the upper surface and the lower surface comprise teeth.

10. The implant ofclaim 1, wherein the distal end portion comprises a tooth-free zone.

11. The implant ofclaim 1, wherein the body further comprises a longitudinal opening extending through the upper surface and the lower surface.

12. An articulating implant comprising:

a body having a proximal end portion and a distal end portion, first and second side surfaces that extend between the proximal end portion and the distal end portion, and upper and lower surfaces that extend between the proximal end portion and the distal end portion,

a recess formed in the proximal end portion;

an articulating element received in the recess, wherein the articulating element comprises an upper flat surface, a lower flat surface, and an aperture in between the upper and lower flat surfaces for receiving a portion of a delivery instrument therein;

a blocking element extending through an opening in the upper surface and configured to prevent back-out of the articulating element from the recess; and

a separate motion limiting member received in a groove in the recess.

13. The implant ofclaim 12, wherein the motion limiting member is a cylindrical peg.

14. The implant ofclaim 12, wherein the motion limiting member is enlarged relative to the blocking element.

15. The implant ofclaim 12, wherein the blocking element is at least partially in the form of a cylindrical post.

16. The implant ofclaim 12, wherein the motion limiting member is configured to prevent over-rotation of the articulating element.

17. The implant ofclaim 12, wherein the blocking element extends through an opening in the lower surface of the implant.

18. The implant ofclaim 12, wherein the first side surface is convexly curved and the second side surface is concavely curved.

19. The implant ofclaim 12, wherein the distal end portion comprises a tapered surface.

20. The implant ofclaim 12, wherein the upper surface and the lower surface comprise teeth.

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