Patent Description:
As people age, the intervertebral discs in the spinal column may start to deteriorate. Subsequently, the intervertebral discs being to lose height. As a result of the loss of height between vertebral bodies, the nerves exiting from the spinal canal become compressed and pinched, which causes pain among other neurological deficits. One solution is to insert a spacer in place of the disc to restore the height and to promote fusion between adjacent vertebral bodies to permanently maintain the height restoration. Additional fixation is also needed to stabilize the spinal segment. A plate is usually provided, the plate being positioned on the anterior portions of the adjacent vertebral bodies. In some cases, the profile of the plate becomes obstructive to the anatomy. The approach to the spine is also significant in that a direct anterior approach requires navigation or dissection of vascular anatomy. As a result, there is a need to incorporate the plate and the spacer into one device, to limit any profile protruding out of the spine column, and to avoid proximal anatomy from a direct anterior approach. With regard to corpectomy devices, there is a similar need for access to perform the corpectomy and suitable devices to replace at least a portion of damaged or collapsed vertebrae.

<CIT>, <CIT>, and <CIT> all describe implants known in the art.

To meet this and other needs, stand-alone interbody fusion implants and corpectomy implants suitable for an oblique or anterolateral approach to the spine or for use with an oblique corpectomy are provided. The shape and configuration of the implants are particularly suitable for an oblique or anterolateral approach to the spine due to the asymmetrical nature of the implant design. The multi-component spacer and plate are also contained within the disc space to provide for a low or zero profile with respect to the anterior and lateral aspects of the spinal column. Thus, the plate and spacer are incorporated into a single device and any profile protruding out of the spinal column is limited.

According to the invention it is provided an intervertebral implant for implantation in an intervertebral space according to claim <NUM>. Further advantageous aspects of the invention are set forth in the dependent claims.

The asymmetrical nature of the implant may allow for an oblique or anterolateral approach to the spine (e.g., lumbar, cervical). In particular, the implant may be inserted in an oblique direction, e.g., at an angle of about <NUM>° with respect to the mid-sagittal plane. By providing this oblique or anterolateral approach, no dissection of the vessels in front of the vertebrae is required. Thus, the vascular anatomy of the patient may be avoided. In addition, when fully inserted, the implant may be contained within the disc space to provide for a low or zero profile design in regard to the anterior and lateral aspects of the spinal column.

The implant may be asymmetrical in a number of different ways. The spacer has a substantially U-shaped body, which may be asymmetrical along the median plane, the oblique plane, or both planes. The plate may have a curved body, which also may be asymmetrical along the median plane, the oblique plane, or both planes. Thus, the plate, the spacer, or both of the plate and the spacer may be independently asymmetrical. The plate may be asymmetrical along the oblique plane where the first end of the plate extends a distance beyond the second end of the plate or vice versa. Similarly, the spacer may be asymmetrical along the oblique plane where the second end of the spacer extends a distance beyond the first end of the spacer or vice versa. The spacer may further include a leading taper. The leading taper may be located along the insertion direction of the implant, which in the case of an oblique direction may allow for the leading taper to be positioned asymmetrically on the spacer. For example, the leading taper may be asymmetrically positioned such that the leading taper crosses or intersects the oblique plane.

The spacer and the plate may be coupled or connected together in any suitable manner. In one embodiment, the first and second ends of the plate and the first and second ends of the spacer each comprise first and second projections with a recess defined therebetween. The first projections of the spacer may include a sloped upper surface which corresponds to a sloped lower surface of the first projections of the plate. At least one of the first and second projections of the plate or the spacer is matingly received in the corresponding recess of the plate or the spacer. For example, the second projections of the plate may be dovetailed or friction fit within the recesses of the spacer. In addition or in the alternative, the spacer and the plate may be secured together with pins.

According to the invention, the plate the implant includes one or more bores or through holes designed to accommodate fixation devices or fasteners, such as screws. The anterior surface includes one or more eyebrows projecting past the upper or lower surfaces which accommodate the locations of the through holes. The holes for receiving fasteners, such as screws traverse the anterior surface of the plate at an angle divergent to a horizontal plane in order to secure the implant to one or both of the adjacent vertebrae. The implant may also include a locking mechanism disposed on the plate for preventing back out of the screws. For example, a cam-style blocking mechanism may be used with screws that capture the fixation device screws once they are inserted fully into the plate.

Unlike traditional spacers, which may contain one or more graft retaining areas where the spacer completely surrounds or envelops the graft retaining area, the spacer is substantially U-shaped with an open portion. When the spacer and plate are coupled together, the spacer and the plate together define an open graft area. In other words, the perimeter of the U-shaped spacer and the perimeter of the plate define an open area. The open graft area may extend from the superior surface to the inferior surface of the spacer. The opening may be configured for receiving bone graft material to promote fusion of the adjacent vertebral bodies. The spacer may also include a plurality of protrusions on the contact areas of the superior and inferior surfaces for engaging the adjacent vertebrae.

The plate and the spacer may be formed from any suitable biocompatible materials. For example, the plate may be manufactured from a biocompatible metal, such as titanium, for example. The spacer also may be manufactured from any suitable material, such as a biocompatible plastic, like polyether ether ketone (PEEK), for example.

It is also described but it is not part of the invention, a multi-level corpectomy implant for implantation in at least a portion of at least one vertebrae and in an intervertebral space between adjacent vertebrae includes a spacer. The spacer has a superior surface, an inferior surface, a first lateral surface, a second lateral surface, a front surface, and a rear surface. The first and second lateral surfaces each have at least one contact area configured to engage a portion of the vertebrae exposed by a corpectomy. The spacer is also configured to extend between at least two adjacent vertebrae. The spacer is shaped and configured to allow for an oblique or anterolateral approach.

The spacer may include at least one attachment mechanism to secure the spacer to the portion of the vertebrae exposed by the corpectomy. For example, the attachment mechanism may include one or more fasteners, screws, pins, or the like. In addition or in the alternative, the attachment mechanism may include a plurality of protrusions on the contact areas of the first and second lateral surfaces for engaging the portion of the vertebrae exposed by the corpectomy.

The multi-level corpectomy implant may also include one or more plates. The plate may be coupled to a portion of the front surface of the spacer. The plate has an anterior surface and at least one hole traversing through the anterior surface for receiving a fastener, such as a screw to secure the plate to one of the adjacent vertebrae. The implant may include two plates: a first plate coupled to a first portion of the front surface of the spacer and a second plate coupled to a second portion of the front surface of the spacer. The first plate may secure the spacer to a first vertebral body and the second plate may secure the spacer to a second vertebral body adjacent to the first vertebral body, for example, using one or more screws.

The plate and spacer may be comprised of any suitable material. For example, the spacer may be formed from a flexible elastomer. The spacer may also include a multi-component body including a biocompatible plastic and a flexible elastomer. The spacer may include a multi-component body including a first cage made from a biocompatible plastic (e.g., PEEK), a second cage comprising a biocompatible plastic (e.g., PEEK), and a flexible elastomer sandwiched between the first and second cages. The first and second lateral surfaces of the first cage and the second cage may each have the contact area configured to engage the portion of the vertebrae exposed by the corpectomy. In addition, the first and second cages may each define an open graft area extending from the first lateral surface to the second lateral surface suitable for receiving bone graft material. According to a further aspect, not forming part of the invention as claimed, it is provided an intervertebral implant for implantation in an intervertebral space between adjacent vertebrae, the implant comprising: a spacer having a substantially U-shaped body, a superior surface, an inferior surface, a first end, and a second end, wherein the inferior surface and the superior surfaces each have a contact area configured to engage adjacent vertebrae; and a plate having an upper surface, a lower surface, a first end, a second end, and at least one hole traversing the plate for receiving a fastener; wherein the plate is coupled to the spacer such that the first end of the spacer engages the first end of the plate and the second end of the spacer engages the second end of the plate, and wherein the implant is asymmetrical such that a median plane divides the spacer and the plate into two asymmetrical halves and wherein the spacer comprises a biocompatible plastic. It is described but it is not part of the invention a multi-level corpectomy implant for implantation in at least a portion of at least one vertebrae and in an intervertebral space between adjacent vertebrae, the implant comprising: a spacer having a superior surface, an inferior surface, a first lateral surface, a second lateral surface, a front surface, and a rear surface, wherein the first and second lateral surfaces each have at least one contact area configured to engage a portion of the vertebrae exposed by a corpectomy and the spacer is configured to extend between at least two adjacent vertebrae; and at least one plate coupled to a portion of the front surface of the spacer, the at least one plate having an anterior surface and at least one hole traversing through the anterior surface for receiving a fastener to secure the at least one plate to one of the at least two adjacent vertebrae, wherein the spacer is shaped and configured to allow for an oblique or anterolateral approach. In a version, the spacer comprises a flexible elastomer. In a further version, the spacer comprises a multi-component body including a first cage comprising a biocompatible plastic, a second cage comprising a biocompatible plastic, and a flexible elastomer sandwiched between the first and second cages. In another version the first and second lateral surfaces of the first cage and the second cage each have the at least one contact area configured to engage the portion of the vertebrae exposed by the corpectomy, and the first and second cages each define an open graft area extending from the first lateral surface to the second lateral surface.

The invention is best understood from the following detailed description when read in connection with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not to scale. Included in the drawing are the following figures:.

Embodiments of the disclosure are generally directed to stand-alone interbody fusion implants and corpectomy implants suitable for use with oblique implantation. Specifically, the implants are designed to allow for an oblique or anterolateral approach to the spine, including the lumbar and cervical spine. In particular, the implants may be inserted in an oblique direction, e.g., at an angle of about <NUM>° with respect to the mid-sagittal plane. By providing this oblique or anterolateral approach, no dissection of the vessels in front of the vertebrae is required and contact with the vascular anatomy of the patient can be avoided or minimized.

Certain embodiments may be used on the cervical, thoracic, lumbar, and/or sacral segments of the spine. For example, the size and mass increase of the vertebrae in the spine from the cervical to the lumbar portions is directly related to an increased capacity for supporting larger loads. This increase in load bearing capacity, however, is paralleled by a decrease in flexibility and an increase in susceptibility to strain. When rigid immobilization systems are used in the lumbar segment, the flexibility is decreased even further beyond the natural motion restriction of that segment. Replacing the conventional rigid immobilization systems with certain embodiments disclosed herein may generally restore a more natural movement and provide added support to the strain-susceptible areas.

As used herein and in the claims, the terms "comprising" and "including" are inclusive or open-ended and do not exclude additional unrecited elements, compositional components, or method steps. Accordingly, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of.

<FIG> illustrate different views of one particular embodiment of the stand-alone intervertebral implant <NUM>. As shown in the exploded view of <FIG>, the implant <NUM> includes a spacer <NUM> and a plate <NUM>. The spacer <NUM> includes a superior surface <NUM> and an inferior surface <NUM>. The superior and inferior surfaces <NUM>, <NUM> each have a contact area <NUM> configured to contact and engage adjacent vertebrae <NUM>. The spacer <NUM> has a curved or substantially U-shaped body with a first end <NUM> and a second end <NUM>. The plate <NUM> has an upper surface <NUM>, a lower surface <NUM>, an anterior surface <NUM>, a first end <NUM>, a second end <NUM>, and at least one bore or screw hole <NUM> traversing the plate <NUM> for receiving a screw <NUM>. The plate <NUM> is affixed to the spacer <NUM>. In particular, the plate <NUM> is coupled to the spacer <NUM> where the first end <NUM> of the spacer <NUM> engages or joins the first end <NUM> of the plate <NUM> and the second end <NUM> of the spacer <NUM> engages or joins the second end <NUM> of the plate <NUM>.

As is evident in <FIG>, the implant <NUM> is asymmetrical such that a median plane M divides the spacer <NUM> and the plate <NUM> into two asymmetrical halves. In addition or in the alternative, the implant <NUM> may be asymmetrical such that an oblique plane O divides the spacer <NUM> and the plate <NUM> into two asymmetrical halves. As used herein, asymmetrical is intended to encompass an implant <NUM> lacking symmetry from side-to-side along either or both the median plane M and the oblique plane O when viewed from a top elevation, for example, as provided in <FIG>. In other words, the median plane M and/or the oblique plane O bisect the implant <NUM> into two parts that are not identical or mirror images of one another.

The asymmetrical nature of the implant <NUM> may allow for an oblique or anterolateral approach to the spine (e.g., lumbar, cervical). In particular, the implant <NUM> may be inserted in an oblique direction along the oblique plane O. As shown in <FIG> and <FIG>, the oblique plane O may be at an angle A relative to the mid-sagittal plane S (e.g., the same as the median plane M). The angle A may be an angle of about <NUM>° with respect to the mid-sagittal plane S and/or the median plane M. For example, the angle A may range from about <NUM>° to about <NUM>°, about <NUM>° to about <NUM>°, about <NUM>° to about <NUM>°, or about <NUM>° to <NUM>° with respect to the mid-sagittal plane S and/or the median plane M. This approach by a surgeon can minimize the contact with the vascular anatomy and need to dissect vessels in front of the vertebrae, which is necessary with an anterior approach.

The implant <NUM> may be asymmetrical based on different configurations of the plate <NUM> and the spacer <NUM>. The spacer <NUM> has a curved, C-shaped, or substantially U-shaped body, which may be asymmetrical along the median plane M, the oblique plane O, or both planes. The plate <NUM> may also have a curved, C-shaped, or substantially U-shaped body, which also may be asymmetrical along the median plane M, the oblique plane O, or both planes. Thus, the plate <NUM>, the spacer <NUM>, or both of the plate <NUM> and the spacer <NUM> may be independently asymmetrical. The shape of the spacer <NUM> and the plate <NUM> may also be asymmetrical in that the curve is not consistent. In other words, the curved body for each of the spacer <NUM> and the plate <NUM> may be skewed from a normal or symmetric curve. In addition, the perimeter of the curved body for each of the spacer <NUM> and the plate <NUM> may contain flat or angled segments along the perimeter or periphery of the implant <NUM>.

As is evident in <FIG> and <FIG>, the plate <NUM> may be asymmetrical along the oblique plane O such that the first end <NUM> of the plate <NUM> extends a distance d1 beyond the second end <NUM> of the plate <NUM>. In other words, the distance d1 is a relative distance between the length of the first end <NUM> of the plate <NUM> less the length of the second end <NUM> of the plate <NUM>. In a corresponding manner, the spacer <NUM> may be asymmetrical along the oblique plane O where the second end <NUM> of the spacer <NUM> extends a distance d2 beyond the first end <NUM> of the spacer <NUM>. Thus, the first and second ends <NUM>, <NUM> of the plate <NUM> are not equivalent or uniform. Again, the distance d2 is a relative distance between the length of the second end <NUM> of the spacer <NUM> less the length of the first end <NUM> of the spacer <NUM>. The first and second ends <NUM>, <NUM> of the spacer <NUM> are also not equivalent. Although not shown, the distance, length, or configuration of the ends or any portion of the plate <NUM> or the spacer <NUM> may be reversed or modified as would be appreciated by one of ordinary skill in the art to provide an asymmetrical implant <NUM> especially appropriate for insertion and implantation along the oblique plane O.

The spacer <NUM> may further include a leading taper <NUM> for ease of insertion. The leading taper <NUM> may be in the form of a chamfer or a bevel which enables self-distraction of the vertebral bodies <NUM> during insertion of the implant <NUM>. The leading taper <NUM> may be located along the insertion direction of the implant <NUM> (e.g., along the oblique plane O). In the case of an oblique insertion direction, the leading taper <NUM> is positioned asymmetrically on the spacer <NUM> with respect to the median plane M. In addition, the leading taper <NUM> may be asymmetrically positioned such that the leading taper <NUM> also crosses or intersects the oblique plane O. As shown in <FIG>, the leading taper <NUM> may intersect the oblique plane O, but the oblique plane O does not necessarily need to bisect the leading taper <NUM> into equal parts. The leading taper <NUM> may correspond to the angle A, which may range from about <NUM>° to about <NUM>°, about <NUM>° to about <NUM>°, about <NUM>° to about <NUM>°, about <NUM>° to <NUM>°, or about <NUM>%, for example.

The spacer <NUM> and the plate <NUM> may be coupled, removably coupled, connected, or attached together in any suitable manner known in the art. The spacer <NUM> and the plate <NUM> may also be coupled together through appropriate coupling means or fasteners. Portions of the spacer <NUM> and the plate <NUM> may be assembled together using, alone or in combination, a friction fit, a dovetail assembly, dowel pins, hooks, staples, screws, adhesives, and the like, or any suitable fasteners known in the art, which can be used to permanently attach the spacer <NUM> and the plate <NUM> together. The implant <NUM> is in the form of a stand-alone fusion device to provide structural stability and a low or zero profile design. The implant <NUM> is preferably assembled before insertion into the disc space.

According to one embodiment shown in <FIG>, the first and second ends <NUM>, <NUM> of the spacer <NUM> may be attached to the first and second ends <NUM>, <NUM> of the plate <NUM> in the form of a friction fit assembly with or without pins <NUM> (shown in <FIG>). For example, the first and second ends <NUM>, <NUM> of the spacer <NUM> each comprise first and second projections <NUM>, <NUM> with a recess <NUM> defined therebetween. The first and second ends <NUM>, <NUM> of the plate <NUM> also each comprise first and second projections <NUM>, <NUM> with a recess <NUM> defined therebetween. At least one of the first and second projections <NUM>, <NUM> of the spacer <NUM> or the first and second projections <NUM>, <NUM> of the plate <NUM> is matingly received in the corresponding recess <NUM> of the spacer or the recess <NUM> of the plate <NUM>. For example, the second projections <NUM> of the plate <NUM> may be dovetailed or friction fit within the recesses <NUM> of the spacer <NUM> or the second projections <NUM> of the spacer <NUM> may be dovetailed or friction fit within the recesses <NUM> of the plate <NUM>. The first projections <NUM> of the spacer <NUM> may be received within the recess <NUM> of the plate <NUM> or the first projections <NUM> of the plate <NUM> may be received within the recess <NUM> of the spacer <NUM>.

In the embodiment shown in <FIG>, the second projections <NUM> of the plate <NUM> are received within the recesses <NUM> of the spacer <NUM> and the first projections <NUM> of the spacer <NUM> are received with the recesses <NUM> of the plate <NUM> to couple the spacer <NUM> and the plate <NUM> together. In addition, the first projections <NUM> of the spacer <NUM> may include a sloped upper surface <NUM>. The first projections <NUM> of the plate <NUM> may include a sloped lower surface <NUM>. The sloped upper surface <NUM> of the first projections <NUM> of the spacer <NUM> may therefore correspond and mate with the sloped lower surface <NUM> of the first projections <NUM> of the plate <NUM> to further secure the first end <NUM> of the spacer <NUM> to the the first end <NUM> of the plate <NUM> and the second end <NUM> of the spacer <NUM> to the second end <NUM> of the plate <NUM>.

In addition or in the alternative, as shown in <FIG>, the spacer <NUM> and the plate <NUM> may be secured together with pins <NUM> which traverse at least a portion of the spacer <NUM> and/or the plate <NUM> at a position proximate to either or both of the first and second ends <NUM>, <NUM> of the spacer <NUM> and the first and second end <NUM>, <NUM> of the plate <NUM>. These pins <NUM> may pass through holes (not shown), for example, in a substantially perpendicular manner relative to a horizontal plane. For example, the pins <NUM> may be oriented substantially perpendicular relative to the superior and/or inferior surfaces <NUM>, <NUM> of the spacer <NUM> and/or the upper and/or lower surfaces <NUM>, <NUM> of the plate <NUM>. The pins <NUM> may pass through the first and second projections of the <NUM>, <NUM> of the spacer <NUM> and the first and second projections <NUM>, <NUM> of the plate <NUM>. The pins <NUM> may be in the form of dowels formed from a biocompatible material, such as titanium, or the pins <NUM> may be formed from tantalum, for example, to enable radiographic visualization.

As depicted in <FIG>, the intervertebral implant <NUM> may be implanted in an intervertebral space <NUM> between adjacent vertebrae <NUM>. In particular, the implant <NUM> may be implanted in the intervertebral space <NUM> between a first superior vertebra <NUM> and a second inferior vertebra <NUM>. In order to engage the adjacent vertebrae <NUM>, the spacer <NUM> may include a plurality of protrusions <NUM> or teeth on the contact areas <NUM> of the superior and/or inferior surfaces <NUM>, <NUM>. The protrusions <NUM> on the superior and inferior surfaces <NUM>, <NUM> of each implant <NUM> grip the endplates of the adjacent vertebrae <NUM>, resist migration, and aid in expulsion resistance. The plurality of protrusions <NUM> may be pyramidal in shape, but the protrusions <NUM> can be configured to be any size or shape to enhance anchoring the spacer <NUM> and the implant <NUM> to each of the adjacent vertebrae <NUM>.

The implant <NUM> may also contain an opening <NUM> configured for receiving bone graft material to promote fusion of the adjacent vertebral bodies <NUM>. Unlike a traditional spacer having an opening for receiving graft materials where the spacer completely surrounds or envelops the graft retaining area, the spacer <NUM>, as shown in <FIG>, for example, has a curvature to match the vertebral endplate <NUM>. In particular, the spacer <NUM> has a substantially U-shaped body with a completely open portion defined between the first and second ends <NUM>, <NUM>. It is only when the spacer <NUM> and plate <NUM> are coupled together that the plate <NUM> closes the open portion of the spacer <NUM>. It is the combination of the spacer <NUM> and the plate <NUM> together that defines the inner void or open graft area <NUM>. In other words, the perimeter of the U-shaped spacer <NUM> and the perimeter of the plate <NUM> together define the inner void or open area <NUM>. The open graft area <NUM> may extend from the superior surface <NUM> to the inferior surface <NUM> of the spacer <NUM> to define a substantially hollow center suitable for retaining one or more bone graft materials.

The intervertebral implant <NUM> may be positioned in the spine after the disc portion between the two vertebral bodies <NUM> is exposed and removed, for example, using rongeurs or other suitable instruments. The posterior and lateral walls of the annulus are generally preserved to provide peripheral support for the implant <NUM> and graft materials. A trial device attached to a trial holder may then be inserted into the disc space <NUM> to determine size of the implant <NUM>. This procedure is generally conducted using fluoroscopy and tactile feel. The implant <NUM> may be available in various heights and geometric options to fit the anatomical needs of a wide variety of patients. After the appropriate sized implant <NUM> is selected and attached to an implant holder and drill guide (not shown), the implant <NUM> may be inserted into the disc space <NUM>. Before or after the implant <NUM> is positioned within the disc space <NUM>, supplemental graft material can be used to enhance fusion. The implant <NUM> may be implanted in the vertebral space <NUM> using an oblique, anterolateral, anterior, posterior, lateral, and/or transforaminal approach.

The implant <NUM> is preferably implanted in the vertebral space <NUM> using an oblique or anterolateral approach. <FIG> depicts a top view of of the portion of the lumbar spine including the anterior side <NUM> and the posterior side <NUM>, with the intervertebral implant <NUM> implanted between adjacent vertebrae <NUM>. As shown, the implant <NUM> may be placed in the lumbar spine in an oblique direction along the oblique plane O. The oblique plane O may be at an angle A relative to the mid-sagittal plane S. The angle A may be about <NUM>° with respect to the mid-sagittal plane S. The asymmetrical nature of the implant <NUM> allows for this oblique or anterolateral approach to the lumbar spine and oblique positioning between the adjacent vertebrae <NUM>. Although depicted on the left side in the quadrant proximate to the anterior side <NUM> of the vertebra <NUM>, a similar oblique approach may be taken to position the implant <NUM> on the right side in the quadrant opposite to the mid-sagittal plane S of the vertebrae <NUM>. When fully inserted, the implant <NUM> can be fully contained within the disc space <NUM> to provide for a zero-profile in regard to the anterior and lateral aspects of the spinal column. In particular, the implant <NUM> does not extend beyond the anterior face <NUM> or lateral side of the vertebrae <NUM>.

The implant <NUM> may be secured to the adjacent vertebrae <NUM> in any suitable manner known in the art. The implant <NUM> may be secured with fasteners, screws, pins, nails, or the like. As shown in <FIG>, the plate <NUM> of the implant <NUM> may be secured to the adjacent vertebrae <NUM> using one or more screws <NUM>. The plate <NUM> includes one or more screw holes <NUM> to receive the screws <NUM>. The screw holes <NUM> are configured to receive the screws <NUM> at various angles. The screw holes <NUM> for receiving the screw <NUM> may traverse the anterior surface <NUM> of the plate <NUM> at an angle divergent to a horizontal plane in order to secure the implant <NUM> to one or both of the adjacent vertebrae <NUM>. Thus, the screws <NUM> enter the screw holes <NUM> at specified angles to enter the adjacent vertebrae <NUM> at the optimal locations. For example, the screws <NUM> may be aligned so that they anchor into the apophyseal rings of two adjacent vertebral bodies <NUM>.

According to the invention, the anterior surface <NUM> of the plate <NUM> includes one or more eyebrows <NUM> projecting past or beyond the upper or lower surfaces <NUM>, <NUM> of the plate <NUM> providing passage for one or more angled screw holes <NUM> designed to accommodate one or more angles screws <NUM>. As shown in <FIG>, the anterior surface <NUM> of the plate <NUM> may include two eyebrows <NUM> extending beyond the upper surface <NUM> of the plate <NUM> to accommodate two angled screw holes <NUM>, which are retaining two angled screws <NUM> configured to secure the implant <NUM> into the superior vertebra <NUM>. The plate <NUM> also includes one eyebrow <NUM> extending below the lower surface <NUM> of the plate <NUM> to accommodate one angled screw hole <NUM>, which is retaining a single angled screws configured to secure the implant <NUM> into the inferior vertebra <NUM>. The eyebrows <NUM> may be rounded and smooth or notched. Although depicted with three screws <NUM> and with two eyebrows <NUM> extending beyond the upper surface <NUM> and one eyebrow extending beyond the lower surface <NUM>, the eyebrows <NUM> and positioning of the screws <NUM> may be modified to accept any suitable number and configuration of screws <NUM> needed to secure the implant <NUM> to the adjacent vertebrae <NUM>.

Once the implant <NUM> is positioned inside the disc space <NUM>, an awl or any similar type of instrument, for example, can be used to drill through the screw hole <NUM> and break the cortex of the adjacent vertebral body <NUM>. The surgeon performing this procedure may then use a depth gauge to determine the screw length. Once the appropriate screw length is determined, screws <NUM> may be inserted using a self-retaining screwdriver, for example. Any suitable type of screw <NUM> may be selected by one of ordinary skill in the art. For example, the screws <NUM> may include fixed or variable angle screws of any suitable size with appropriate thread spacing, thread pitch, head design, length, and the like.

Once inserted, the screws <NUM> may be secured with an anti-back out prevention or locking mechanism <NUM>. As depicted in <FIG>, the locking mechanism <NUM> may be disposed on the plate <NUM> (e.g., the anterior surface <NUM>) for preventing back out of the screws <NUM>. For example, a cam-style blocking mechanism may be used with screws <NUM> that capture the fixation device screws <NUM> once they are inserted fully into the plate <NUM>. One or more screw holes <NUM> may be provided on the anterior surface <NUM> of the plate <NUM>, which at least partially overlap with the screw holes <NUM>. As shown, the anti-back out mechanism <NUM> may include two set screws <NUM> that retain the screws <NUM> with the implant <NUM>, although any suitable anti-back out mechanism <NUM> may be selected by one of ordinary skill in the art.

The plate <NUM> and spacer <NUM> may be comprised of any suitable material. The spacer <NUM> can be comprised of any material that is conducive to the enhancement of fusion between the two adjacent vertebrae <NUM>. In one particular embodiment, the spacer <NUM> is made of a biocompatible plastic, like polyether ether ketone (PEEK), polyetherketoneketone (PEKK), ultra-high molecular weight (UHMW) polyethylene, or other polymers and plastics known in the art which are physiologically compatible. Any other materials that are physiologically compatible may also be used such as bone or metal. The plate <NUM> can also be comprised of any physiologically compatible material. In the preferred embodiment, the plate <NUM> is composed of a biocompatible metal, such as stainless steel, titanium, titanium alloys, surgical steel, and metal alloys, for example. Preferably, the plate is formed from titanium or a titanium alloy. Any other materials that are physiologically compatible may also be used such as bone or plastic.

According to one embodiment, the multi-part low or zero-profile implant <NUM> is configured to be positioned in between the vertebral bodies <NUM>. A PEEK spacer <NUM> is provided that is configured to be attachable to a titanium plate <NUM>. The PEEK spacer <NUM> is further provided with a curvature to match the vertebral endplate <NUM>, a leading taper <NUM> for ease of insertion and teeth or protrusions <NUM> on the superior and inferior surfaces <NUM>, <NUM> that engage with the endplates of the adjacent vertebral bodies <NUM> to resist migration. There is also provided a through hole <NUM> that extends from the superior surface <NUM> to the inferior surface <NUM> of the spacer <NUM> for receiving bone graft material to promote fusion of the adjacent vertebral bodies <NUM>.

The titanium plate <NUM> is provided with bore holes <NUM> that are configured to accept fastening devices, such as screws <NUM> for fixation to the vertebral bodies <NUM>. It should be noted that rather than screws, pins or nail type devices may also be used. The bore holes <NUM> are aligned so that they anchor into the apophyseal rings of the two adjacent vertebral bodes <NUM> for increased fixation. In this particular embodiment, the cam-style blocking mechanism <NUM> is provided. Specifically, the cam-style blocking mechanism <NUM> comprises screws <NUM> that when turned capture the fixations devices or screws <NUM> once they are inserted fully into the plate <NUM>. The shape of the implant <NUM> is configured so that an anterior, oblique, anterolateral, lateral, and/or transforaminal approach may be used in positioning the plate <NUM> and the spacer <NUM> in the intervertebral space <NUM>. When the implant <NUM> is fully inserted, the implant <NUM> will be contained within the disc space <NUM> and will have a zero profile with regard to the anterior and lateral aspects of the spinal column.

According to another embodiment, as illustrated in <FIG> and <FIG>, there is provided an oblique spacer <NUM> that may be used as a corpectomy device. Specifically, a multi-level corpectomy implant <NUM> includes a spacer <NUM> for implantation in at least a portion of at least one vertebrae <NUM> and in an intervertebral space <NUM> between adjacent vertebrae <NUM>. The spacer <NUM> includes a superior surface <NUM>, an inferior surface <NUM>, a first lateral surface <NUM>, a second lateral surface <NUM>, a front surface <NUM>, and a rear surface <NUM>. The first and second lateral surfaces <NUM>, <NUM> each have at least one contact area <NUM> configured to engage a portion <NUM> of the vertebrae <NUM> exposed by a corpectomy. The spacer <NUM> is also configured to extend in the intervertebral space <NUM> between at least two adjacent vertebrae <NUM>. The spacer <NUM> is shaped and configured to allow for an oblique or anterolateral approach (e.g., at an angle of about <NUM>° with respect to the mid-sagittal plane S).

The spacer <NUM> may include at least one attachment mechanism to secure the spacer <NUM> to the portions <NUM> of the vertebrae <NUM> exposed by the corpectomy. <FIG> depicts two embodiments for the spacer 112a, 112b. For example, the attachment mechanism may include one or more fasteners, screws, pins, or the like. As shown in the spacer 112a, screws or pins <NUM> on the second lateral surface <NUM> and/or the first lateral surface <NUM> (not shown) may be provided to secure the spacer 112a to the portions <NUM> of the vertebrae <NUM> exposed by the corpectomy. In addition or in the alternative, as shown in the spacer 112b, the attachment mechanism may include a plurality of protrusions <NUM> on the contact areas <NUM> of the first and second lateral surfaces <NUM>, <NUM> for engaging the portions <NUM> of the vertebrae <NUM> exposed by the corpectomy.

The corpectomy implant <NUM> may further include at least one plate <NUM>. The one or more plates <NUM> may be coupled to a portion of the front surface <NUM> of the spacer <NUM>. The plate <NUM> has an anterior surface <NUM> and at least one screw hole <NUM> traversing through the anterior surface <NUM> for receiving a screw <NUM> to secure the plate <NUM> to one of the adjacent vertebrae <NUM>. The plate <NUM> may be of any suitable size, shape, or configuration as would be recognized by one of ordinary skill in the art. In one embodiment, the implant <NUM> may include two plates <NUM>: a first plate <NUM> coupled to a first portion of the front surface <NUM> of the spacer <NUM> (e.g., in the region near the superior surface <NUM> proximate to a first vertebra <NUM>) and a second plate <NUM> coupled to a second portion of the front surface <NUM> of the spacer <NUM> (e.g., in the region near the inferior surface <NUM> proximate to the second vertebra <NUM>). Thus, the first plate <NUM> may secure the spacer <NUM> to a first vertebral body <NUM> and the second plate <NUM> may secure the spacer <NUM> to a second vertebral body <NUM>, for example, using one or more screws <NUM>.

The plate <NUM> and the spacer <NUM> may be comprised of any suitable material. <FIG> depicts two embodiments for the spacer 112a, 112b. For example, the spacer 112a may be formed from a flexible elastomer. Suitable elastomers may include, for example, polyurethanes, silicones, hydrogels, collagens, hyalurons, cryogels, proteins and other synthetic polymers that are configured to have a desired range of elastomeric mechanical properties, such as a suitable compressive elastic stiffness and/or elastic modulus. The elastomer is flexible in that it may be slightly flexed or bent, but the elastomer returns to its original shape.

The spacer 112b may include a multi-component body including a biocompatible plastic and a flexible elastomer. Biocompatible plastics may include polyetheretherketone (PEEK), polyetherketoneketone (PEKK), ultra-high molecular weight (UHMW) polyethylene, or other polymers and plastics known in the art which are biocompatible. The flexible elastomers include the same elastomers as discussed above. Specifically, the spacer 112b may include a multi-component body including a first cage <NUM> made from a biocompatible plastic (e.g., PEEK), a second cage <NUM> comprising a biocompatible plastic (e.g., PEEK), and a connector portion <NUM> comprising a flexible elastomer sandwiched between the first and second cages <NUM>, <NUM>. The first and second lateral surfaces <NUM>, <NUM> of the first cage <NUM> and the second cage <NUM> may each contain the contact area <NUM> configured to engage the portions <NUM> of the vertebrae <NUM> exposed by the corpectomy. In addition, the first and second cages <NUM>, <NUM> may each define an open graft area <NUM> extending from the first lateral surface <NUM> to the second lateral surface <NUM> suitable for receiving bone graft material. The implants <NUM> may be available in various heights and geometric options to fit the anatomical needs of a wide variety of patients.

These implants <NUM>, <NUM> are specially designed to allow for an oblique or anterolateral approach to the spine (e.g., lumbar, cervical). In particular, the implants <NUM>, <NUM> may be inserted in an oblique direction with respect to the mid-sagittal plane S. By providing access to the spine with this oblique or anterolateral approach, no dissection of the vessels in front of the vertebrae is required and contact with the vascular anatomy of the patient can be avoided or minimized. The shape and configuration of the implants <NUM>, <NUM> are particularly suitable for the oblique approach based on the asymmetrical nature of the implant <NUM> and the oblique spacer <NUM> design of the corpectomy implant <NUM>.

Claim 1:
An intervertebral implant (<NUM>) for implantation in an intervertebral space (<NUM>) between adjacent vertebrae, the implant comprising:
- a spacer (<NUM>) having a substantially U-shaped body, a superior surface (<NUM>), an inferior surface (<NUM>), a first end (<NUM>), and a second end (<NUM>), wherein the inferior surface (<NUM>) and the superior surfaces (<NUM>) each have a contact area (<NUM>) configured to engage adjacent vertebrae (<NUM>); and
- a plate (<NUM>) having an upper surface (<NUM>), a lower surface (<NUM>), a first end (<NUM>), a second end (<NUM>), and at least one hole (<NUM>) traversing the plate (<NUM>) for receiving a fastener (<NUM>);
- wherein the plate (<NUM>) is coupled to the spacer (<NUM>) such that the first end (<NUM>) of the spacer (<NUM>) engages the first end (<NUM>) of the plate (<NUM>) and the second end (<NUM>) of the spacer (<NUM>) engages the second end (<NUM>) of the plate (<NUM>), and
- wherein the implant is asymmetrical such that a median vertical plane (M) of the implant (<NUM>) divides both the spacer (<NUM>) and the plate (<NUM>) into two asymmetrical halves;
wherein the plate (<NUM>) has an anterior surface (<NUM>) comprising one or more eyebrows (<NUM>) projecting past the upper or lower surfaces (<NUM>, <NUM>) of the plate (<NUM>), each eyebrow (<NUM>) providing passage for one of the at least one holes (<NUM>) each designed to accommodate a fastener (<NUM>) such as an angled screw (<NUM>), and wherein each of the at least one holes (<NUM>) for receiving a fastener (<NUM>) traverses the anterior surface (<NUM>) of the plate (<NUM>) at an angle divergent to a horizontal plane.