Abstract:
An intervertebral fixation device is disclosed, which includes a weight-bearing shell, a first anchor, a second anchor, and a key. The shell includes a first and second opposing sidewalls at a distance from one another, a keyway that extends along at least a portion of the distance, and a first axis of rotation and a different second axis of rotation that extend along at least a portion of the distance and are outside the keyway. The first anchor is rotatably coupled to the weight-bearing shell about the first axis of rotation, and the second anchor is rotatably coupled to the weight-bearing shell about the second axis of rotation. The key is insertable into the keyway such that the first anchor and the second anchor are securable in divergent orientations with respect to the weight-bearing shell.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/370,921 filed Feb. 10, 2012, which is a continuation of U.S. patent application Ser. No. 12/246,946, filed Oct. 7, 2008, which claims priority to U.S. Provisional Patent Application No. 60/998,376, filed Oct. 11, 2007, all of which are incorporated herein by reference in their entireties. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The present disclosure relates generally to spinal fusion devices. More specifically, example embodiments are directed a minimally invasive lateral intervertebral system, device and method. 
         [0004]    2. Brief Discussion of Related Art 
         [0005]    Articulations between bony vertebrae of a human spine—such as spinal disks and facet joints—frequently deteriorate with age or trauma and become a source of pain. Spinal disk deterioration causes the spinal disk to lose its normal consistency and volume, which facilitates the spinal disk to collapse and to cause abnormally painful motion across the spinal disk within the spine. The abnormal motion across the deteriorating spinal disk also increases the stresses on the facet joints and accelerates their degeneration, further adding to the abnormally painful motion across the spinal disk of the spine. 
         [0006]    A normal spinal disk is a cylindrical weigh-bearing fibrous structure with a non-compressible viscous center. Due to its ability to deform, the spinal disk not only supports normal functional loads of the human body (e.g., load bearing) but also cushions and evenly distributes the stresses applied with body movement and positioning (e.g., load sharing). The spinal disk articulates between the bony vertebrae—one vertebra above the spinal disk and one vertebra below the spinal disk—through large surface area interfaces known as endplates. An endplate is a thin (e.g., 1 mm-3 mm) and approximately round plate (e.g., 2 cm-4 cm in diameter) of dense bone and cartilage accounting for a majority of the vertebral load-bearing capacity. 
         [0007]    Surgical treatment of spinal disk disorders has required fusion or elimination of movement across the abnormal spinal disk. This has been accomplished by allowing bone to grow between adjacent vertebrae and through a disk space of the abnormal spinal disk. In the foregoing surgical treatment, the disk space of the abnormal disk is restored to its normal height by opening the disk space occupied by the spinal disk, which is removed, while also restoring a normal curvature of the spine determined by a differential height between the front and the back of the spinal disk between adjacent vertebrae (e.g., lordosis). The foregoing restoration is commonly achieved by using a disk implant that opens the space and allows for growth of bridging bone that fuses the adjacent vertebrae. The ultimate effectiveness of the disk implant is based on: (i) its ability to restore and maintain normal curvature of the spine across the disk space; (ii) ease of its insertion and fixation within the disk space; (iii) its facilitation of bony fusion of the adjacent vertebrae; and (iv) its restriction of movement of the adjacent vertebrae in respect to the disk implant across the disk space. 
         [0008]    Disk implants vary in shape but possess similar characteristics with upper and lower surfaces conforming to the shape of the vertebral endplates and vertical designs that aim to restore normal height of the collapsed disk space and to restore normal curvature of spine. The disk implants are sufficiently porous or hollow to allow bridging bone to grow through the disk implants and to bridge the adjacent vertebrae (e.g., bone fusion). These disk implants generally perform well with vertical load bearing and flexion of the spine. However, these disk implants are not able to restrict movement between adjacent vertebrae when the vertebrae are pulled apart, or subjected to extension and lateral bending. These disk implants further provide negligible restriction during translation (e.g., sliding motion) and rotation of the spine. 
         [0009]    Some disk implants cut into or have protrusions directed into or through the endplates of the vertebrae. These protrusions penetrate the endplates and potentially create channels for bone growth, yet do not alter structural properties of the endplates. These protrusions further reduce the risk of extrusion of the disk implants from of the disk space. The protrusions restrict translation of the disk implants but the protrusions do not restrict extension and lateral bending. This necessitates additional fixation or immobilization usually via posterior pedicle screws. 
         [0010]    One of the surgical techniques used to deliver the disk implant is a minimally invasive lateral approach. The minimally invasive lateral approach utilizes a tubular access retractor to remove the spinal disk and to deliver a weight-bearing disk implant. The disk implant delivered via the lateral approach does not provide sufficiently rigid fixation and requires a further surgical procedure to provide posterior fixation of the disk implant. A current solution is to utilize a lateral plate secured with two screws. The lateral plate requires repetitive delivery of multiple components through a small channel and provides a relatively small fixation advantage over the standalone disk implant. The ability to provide sufficient fixation across the disk space through the minimally invasive lateral approach would eliminate the second surgical procedure. 
       SUMMARY 
       [0011]    In a particular embodiment, an intervertebral fixation device is disclosed. The intervertebral fixation device includes a weight-bearing shell, a first anchor, a second anchor and a key. The weight-bearing shell includes a first and second opposing sidewalls at a distance from one another, a keyway that extends along at least a portion of the distance, and a first axis of rotation and a different second axis of rotation that extend along at least a portion of the distance and are outside the keyway. 
         [0012]    The first anchor is rotatably coupled to the weight-bearing shell about the first axis of rotation. The second anchor is rotatably coupled to the weight-bearing shell about the second axis of rotation. 
         [0013]    The key is insertable into the keyway such that the first anchor and the second anchor are securable in divergent orientations with respect to the weight-bearing shell. 
         [0014]    In another particular embodiment, an intervertebral fixation system is disclosed. The intervertebral fixation system includes an intervertebral fixation device. The intervertebral fixation device includes a weight-bearing shell, a first anchor, a second anchor and a key. The weight-bearing shell includes a first and second opposing sidewalls at a distance from one another, a keyway that extends along at least a portion of the distance, and a first axis of rotation and a different second axis of rotation that extend along at least a portion of the distance and are outside the keyway. 
         [0015]    The first anchor is rotatably coupled to the weight-bearing shell about the first axis of rotation. The second anchor is rotatably coupled to the weight-bearing shell about the second axis of rotation. 
         [0016]    The key is insertable into the keyway such that the first anchor and the second anchor are securable in divergent orientations with respect to the weight-bearing shell. 
         [0017]    Other aspects, advantages, and features of the present disclosure will become apparent after review of the entire application, including the following sections: Brief Description of the Drawings, Detailed Description, and the Claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a perspective view of an example shell of a minimally invasive lateral intervertebral fixation device; 
           [0019]      FIG. 2  is an elevated side view of the example shell of  FIG. 1 ; 
           [0020]      FIG. 3  is a side view of the example shell of  FIG. 1 ; 
           [0021]      FIG. 4  is an elevated view of an example anchor of the minimally invasive lateral intervertebral fixation device; 
           [0022]      FIG. 5  is a side translucent view of the example shell of  FIG. 1  with plural example anchors concealed within the shell of  FIG. 1 ; 
           [0023]      FIG. 6  is a perspective translucent view of the shell of  FIG. 1  with plural preloaded anchors in a concealed position within the shell of  FIG. 1 ; 
           [0024]      FIG. 7  is a perspective view of a first embodiment of a minimally invasive lateral intervertebral system; 
           [0025]      FIG. 8  is a perspective view of an example cylindrical key of minimally invasive lateral intervertebral system of  FIG. 7 ; 
           [0026]      FIG. 9  is a perspective view of a second embodiment of a minimally invasive lateral intervertebral system; 
           [0027]      FIG. 10  is a perspective view of a cross-section of the second embodiment of the minimally invasive lateral intervertebral system of  FIG. 9 ; 
           [0028]      FIG. 11  is an elevated side view of a minimally invasive lateral intervertebral fixation device; and 
           [0029]      FIG. 12  is an elevated side view of the minimally invasive lateral intervertebral fixation device of  FIG. 11  with the plural example anchors in a locked and an extended position in relation to the shell of  FIG. 1  and securing a top endplate of a vertebra of a spine. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  is a perspective view  100  of an example shell  101  of a minimally invasive lateral intervertebral fixation device. The minimally invasive lateral intervertebral fixation device is illustrated in and described with reference to  FIG. 11 . The shell  101  is made of a material, such as a thermoplastic, a polymer, or a composite thereof, that is sufficiently resilient to withstand stress or pressure of bodily movement and positioning, while providing a degree of elasticity and also providing biostablity and biocompatibility. The material should have a modulus of elasticity that is comparable to bone. For example, the shell  101  may be made of polyetheretherketone (PEEK), a thermoplastic with a Young&#39;s modulus of elasticity of about 3.6 GPa and a tensile strength of about 90 MPa. Also, because PEEK is resistant to both organic and aqueous environments, it is practical for the minimally invasive lateral intervertebral fixation device. Other materials that may be used include metals, ceramics, medical plastics, coral, and other medically applicable materials. 
         [0031]    In various embodiments, the dimensions of the shell  101  are approximately the following: the length of the shell  101  between sidewalls  102 ,  104  is between about 45 mm and about 55 mm; the width of the shell  101  between the back wall  106  and the front wall  108  is between about 15 mm to about 22 mm; and the height of the shell between top and bottom surfaces  110 ,  122  is between about 8 mm and about 14 mm. It is noted that the foregoing dimensions are non-limiting and may be appropriately adjusted depending on different levels of the spine (e.g., cervical, lumbar, thoracic) and depending on a particular person&#39;s spinal anatomy. 
         [0032]    The shell  101  includes sidewalls  102 ,  104 , intermediate walls  146 ,  148  and  150  between the sidewalls  102 ,  104 , a back wall  106 , a front wall  108 , and top and bottom surfaces  110 ,  112 . One or more of the sidewalls  102 ,  104  include a depression or a recess  114  to interface with an introducer described herein below with reference to  FIGS. 9 and 10 . As is described in reference to  FIGS. 9 and 10 , the introducer includes a reciprocal protrusion to pressure fit the depression or recess  114  of the shell  101 . While the sidewalls  102 ,  104 , the intermediate walls  146 ,  148 ,  150  and the top and bottom surfaces  110 ,  112  are generally flat surfaces, the front wall  108  is a generally curve-shaped or arcuate surface. The sidewalls  102 ,  104  and the intermediate walls  146 ,  148 ,  150  include through holes  116  and  118  aligned at about the top and bottom surfaces  110 ,  112 , forming respective lengthwise channels through the shell  101  to receive and secure to the shell  101  plural anchors (shown in  FIG. 4 ) by using respective pins (not shown) inserted through the respective channels. The respective lengthwise channels through the shell  101  provide respective axes of rotation proximate to the top and bottom surfaces  110 ,  112  of the shell  101 . The through holes  116 ,  118  are disposed proximate to the bottom and the top of the sidewalls  102 ,  104  and the intermediate walls  146 ,  148 ,  150 . The sidewalls  102 ,  104  and the intermediate walls  146 ,  148 ,  150  also include respective key-shaped openings  120 ,  138 ,  140 ,  142 ,  144  (hereinafter collectively referred to as a “keyway opening” or “keyway”  119 ) that provide access to the plural anchors (shown in  FIG. 6 ) to enable their rotation from a concealed position within the shell  101  into an extended and fixed position in relation to the shell  101  (shown in  FIG. 11 ), using a wedge and a cylindrical key (shown in  FIGS. 7 ,  8  and  10 ). Each of the key-shaped openings  120 ,  138 ,  140 ,  142 ,  144  is shaped identically to form the keyway opening or keyway  119  between and through the sidewalls  102 ,  104 . 
         [0033]    The shell  101  includes plural openings  122 ,  124 ,  126  and  128  through the top and bottom surfaces  110 ,  112 , plural openings  130 ,  132 ,  134  and  136  through the back wall  106  and the keyway opening  119  (e.g., plural key-shaped openings  120 ,  138 ,  140 ,  142  and  144 ) between and through the sidewalls  102 ,  104 . Openings  122 ,  128  are about 5 mm-6 mm by about 10 mm-12 mm, and openings  124 ,  126  are about 10 mm-12 mm by about 12 mm-16 mm. Openings  130 ,  132 ,  134  and  136  may be of various sizes. The foregoing plural openings form or define plural chambers (e.g., four chambers) within the shell  101  to facilitate growth of bridging bone through the shell  101  of the minimally invasive lateral intervertebral fixation device. The inner chambers (e.g., innermost two chambers), as indicated by the openings  124 ,  126 , also conceal plural anchors as illustrated in and described in reference to  FIGS. 4-6 . The outer chambers, as indicated by openings  122  and  128  do not conceal any anchors and facilitate locking of the cylindrical key (shown in  FIGS. 7 ,  8  and  10 ). 
         [0034]      FIG. 2  is an elevated side view  200  of the example shell  101  of  FIG. 1 . The keyway  119  (e.g., each of the key-shaped openings  120 ,  138 ,  140 ,  142 ,  144 ) includes four portions  202 ,  204 ,  206  and  208 . A central approximately round portion  202  approximates the circumference of the cylindrical key of  FIG. 8 , while portion  204  approximates the dimension of plural protrusions about the circumference of the cylindrical key of  FIG. 8 . Portions  202  and  204  allow the cylindrical key to move through the keyway  119  when the protrusions are aligned with portion  204  and restrict movement of the cylindrical key when the protrusions of the cylindrical key are not aligned with portion  204 . Portions  202 ,  204 ,  206  and  208  of the keyway  119  facilitate access to and rotation of the plural anchors concealed within the shell  101  (shown in  FIG. 6 ) from their concealed position within the shell  101  into an extended and fixed position in relation to the shell  101  (shown in  FIG. 11 ), using the wedge and the cylindrical key (shown in  FIGS. 7 ,  8  and  10 ). 
         [0035]      FIG. 3  is a side view  300  of the example shell  101  of  FIG. 1 . As illustrated in the side view  300 , the sidewalls  102 ,  104  and the intermediate walls  146 ,  148 ,  150  gradually increase in height from the back wall  106  to the front wall  108 , where the top and bottom surfaces  110 ,  112  are angled with respect to a horizontal plane through a center of the shell  101  (not shown) from the back wall  106  to the front wall  108 . To illustrate, in a particular embodiment, the shell  101  of the minimally invasive lateral intervertebral fixation device has a front height  304  of the front wall  108  that is higher than a back height  302  in the back wall  106  to provide for a natural curvature of the cervical or lumbar segments of the spine into which the minimally invasive lateral intervertebral fixation device may be implanted. The difference between the heights  302 ,  304  may be from about 2 mm to about 3 mm. In an example embodiment, the back height  302  may be about 10 mm and the front height  304  may be about 12 mm. The heights  302 ,  304  may also be equal. As such, the angle may be varied (adjusting the heights  302 ,  304 ) between different levels of the spine (e.g., cervical, lumbar, thoracic) and between different people. The angle between the top surface  110  and the horizontal plane (or the bottom surface  112  and the horizontal plane) may be between zero (0) and six (6) degrees, while a combined angle between the horizontal plane and top and bottom surfaces  110 ,  112  will most commonly be between three (3) and six (6) degrees depending on the level of the spine and a particular person&#39;s spinal anatomy. 
         [0036]      FIG. 4  is an elevated view  400  of an example anchor  401  of the minimally invasive lateral intervertebral fixation device. In a particular embodiment, the anchor  401  is made of a metal, such as titanium. Other medically applicable metals may be employed. The anchor  401  is generally c-shaped, having a generally straight base portion  402  that has a protrusion  403 , which provides a pivot for rotating the anchor  401  with the wedge and the cylindrical key of  FIGS. 7 ,  8  and  10 . Additionally, the protrusion  403  is of a shape that approximates an edge of portion  202  of the key-shaped openings  120 ,  138 ,  140 ,  142 ,  144  so that the cylindrical key better restricts the rotational movement of the anchor  401 . The base portion  402  includes a beveled or chamfered edge  404  to facilitate the wedge in more easily advancing by and rotating the anchor  401 . A projection or arm portion  406  extends in a curve-shaped or arcuate direction from the base portion  402  and is adapted to secure an endplate of a vertebra of the spine. The projection  406  includes a leading pointed or sharp edge  408  adapted to penetrate the endplate of a vertebra of the spine. A cylinder portion  410  is disposed transverse to the base portion  402 . The cylinder portion  410  includes through hole  411  to secure the anchor  401  in the shell  101  (via pins described above inserted via through holes  116  or  118  and via through hole  411 ) and to facilitate the anchor  401  in rotating about the axis of rotation at the top or the bottom surfaces  110 ,  122  of the shell  101  via through hole  411 . In a particular embodiment, the through hole  411  is approximately 1.5 mm and the projection  406  is a curve or arc that is approximately 10 mm from the center of the through hole  411 . The width  412  of the base portion  402  is about half of the length  414  of the cylinder portion  410 . In a particular embodiment, the width  412  is approximately 2.5 mm, the length  414  is approximately 5.5 mm, and the height of the anchor  401  from the base portion  402  to sharp edge  408  is about 12.5 mm. As is described in detail below, an inner surface  416  of the anchor  401  is of a shape that generally approximates the surface  110  or surface  112  of the shell  101  to provide weight-bearing support for the endplate of the vertebra that it will engage. The inner surface  416  may be adjusted to approximate the surface  110  or surface  112  of the shell  101 . The inner surface  416  includes a top edge  422  of the cylinder portion  410  that transitions to a flat edge  420  of the base portion  402  and includes a continuous inclining edge  418  that transitions the flat edge  420  to the arcuate projection or arm  406 . 
         [0037]      FIG. 5  is a side translucent view  500  of the example shell  101  of  FIG. 1  with plural example anchors  502 ,  504  concealed within the shell  101 . A first anchor of the plural anchors  502  is positioned in a first orientation and a second anchor  504  is positioned in a second orientation in relation to the first anchor  502 . More specifically, the second anchor  504  is positioned upside down in relation to the first anchor  502 . The disparate orientations of the anchors  502 ,  504  in relation to one another enables the anchors  502 ,  504  to diverge through the openings  124 ,  126  in the top and bottom surfaces  110 ,  112  and to engage with endplates of respective vertebra of the spine (not shown). The disparate orientations of the anchors  502 ,  504  also facilitate the wedge and the cylindrical key of  FIGS. 7 ,  8  and  10  to be inserted through portions  202 ,  204 ,  206  and  208 , to engage the anchors  502 ,  504  with the endplates of the respective vertebrae and to lock the anchors  502 ,  504  in relation to the shell  101  and the respective vertebrae. 
         [0038]      FIG. 6  is a perspective translucent view  600  of the shell  101  of  FIG. 1  with plural preloaded anchors  602 - 616  in a concealed position within the shell  101 . The shell  101  conceals four ( 4 ) sets of disparately oriented anchors ( 602 ,  610 ), ( 604 ,  612 ), ( 606 ,  614 ), and ( 608 ,  616 ). As illustrated in view  600 , the length of the cylinder portion of each anchor  602 - 616  (e.g., length  414  in  FIG. 4 ) is approximately double of the width of the base portion (e.g., width  412  in  FIG. 4 ) of each anchor  602 - 616 . This allows sufficient width of the cylinder to secure the anchors  602 - 616  to the shell  101  when the anchors  602 - 616  are extended (shown in  FIG. 11 ), while mitigating the amount of space necessary for the anchors  602 - 616 . Anchors ( 602 ,  610 ) and ( 604 ,  612 ) diverge and extend through openings  124  in the top and bottom surfaces  110 ,  112 , while anchors ( 606 ,  614 ) and ( 608 ,  616 ) diverge and extend through openings  126  in the top and bottom surfaces  110 ,  112 . 
         [0039]      FIG. 7  is a perspective view  700  of a first embodiment of a minimally invasive lateral intervertebral system  701 . The minimally invasive lateral intervertebral system  701  includes an example wedge  702  and an example cylindrical key  704  to interface with the example shell  101  and the example plural anchors  602 - 616 . The wedge  702  and cylindrical key  704  are used to rotate the respective sets of anchors ( 602 ,  610 ), ( 604 ,  612 ), ( 606 ,  614 ), and ( 608 ,  616 ), in order from the proximal to the distal, from a concealed position within the shell  101  into an extended and fixed position in relation to the shell  101  (shown in  FIG. 11 ) to engage and secure endplates of respective vertebrae (not shown). For example, the wedge  702  is advanced forward (e.g., via portions  206  and  208  of the keyway  119 ) to rotate a first proximal set of anchors ( 602 ,  610 ) from the concealed position within the shell  101  to an intermediately rotated position in which the base portions of the set of anchors (e.g., base portion  402  of  FIG. 4 ) are disposed within the central portion (e.g., central portion  202  of  FIG. 2 ) of the keyway  119  (e.g., key-shaped opening  138  of  FIG. 1 ). The wedge is similarly advanced from the sidewall  102  to the sidewall  104  to rotate the respective sets of the anchors into intermediately rotated positions. In the intermediately rotated position, the respective sets of anchors have been partially extended from the shell  101  through the openings (e.g., openings  124 ,  126  of  FIG. 1 ) in the top and bottom surfaces of shell  101  (e.g., top and bottom surfaces  110 ,  112 ). The cylindrical key  704  is then advanced forward, fully rotating the first proximal set of anchors ( 602 ,  610 ) and other sets of anchors ( 604 ,  612 ), ( 606 ,  614 ), and ( 608 ,  616 ) into their fully extended positions in relation to the shell  101 . 
         [0040]      FIG. 8  is a perspective view  800  of the example cylindrical key  704  of the minimally invasive lateral intervertebral system of  FIG. 7 . The cylindrical key  704  is made of a solid material, such as PEEK, to provide the same biomechanical properties (e.g., resilience and elasticity) as the shell  101 . The cylindrical key  704  includes a cylinder portion  802  that includes a driving/rotating end  806  and a conical end  804 . The driving/rotating end  806  includes a slit (shown in  FIGS. 10-12 ) for a driver (not shown) that can drive and rotate the cylindrical key  704 . The conical end  804  is offset from the center of the cylinder portion&#39;s  802  diameter to more easily rotate the anchors from the intermediately rotated position to a fully extended position. The cylindrical key  704  further includes protrusions  808  and  810  that facilitate the cylindrical key  704  to be driven forward when the protrusions  808 ,  810  are in a first orientation (e.g., protrusions  808 ,  810  aligned with portion  204  of the keyway  119  shown in  FIGS. 1 and 2 ). The protrusions further facilitate the cylindrical key  704  to secure the respective sets of anchors (e.g.,  602 - 616  of  FIG. 6 ) when the protrusions  808 ,  810  are rotated via the driving/rotating end  812  into a second orientation. More specifically, protrusion  810  may be engaged between sidewall  102  and intermediate wall  146 , while protrusion  810  may be engaged by intermediate wall  150 , to support the sets of anchors (e.g.,  602 - 616  of  FIG. 6 ) in extended positions relative to the shell  101  and to prevent the cylindrical key  704  from dislodging from the shell  101 . In a particular embodiment, the length of the cylindrical key  704  is about 50 mm and its cross-sectional diameter is about 8 mm. In this embodiment, the protrusions  808 ,  810  have a height of about 1.5 mm from the surface of the cylindrical key  704 , where the protrusion  810  has a length of about 6 mm and a width of about 5 mm, and the protrusion  808  has a length of about 2 mm and a width of about 5 mm. In this embodiment, the protrusion  808  includes a chambered or a beveled edge that forms a part of the conical end  804 . 
         [0041]      FIG. 9  is a perspective view of a second embodiment of a minimally invasive lateral intervertebral system  900 . The minimally invasive lateral intervertebral system  900  includes an example introducer  901 , the shell  101  with plural anchors  602 - 616 , the wedge  702 , the cylindrical key  704  (shown in  FIG. 10 ) and an extender/connector  907 . The introducer  901  interfaces with the shell  101  and the cylindrical key  704  to deliver and implant the shell  101 , the plural anchors  602 - 616  and the cylindrical key  704  (e.g., the minimally invasive lateral intervertebral fixation device) into a disk space between plural vertebrae. 
         [0042]    The introducer  901  is made of a rigid radiolucent material, such as a radiolucent metal. In various embodiments, the radiolucent metal may be aluminium, beryllium or other radiolucent metal. In a particular embodiment, the introducer  901  is approximately 20 cm long and has a hollow configuration that approximates the shell  101  shown in  FIG. 1 . The introducer includes a mating protrusion that pressure fits the depression or recess  114  of the shell  101 . The introducer  901  includes a handle portion  902  and a swivel portion  904 . To facilitate the minimally invasive lateral approach in delivering the minimally invasive lateral intervertebral fixation device (shown in  FIG. 11 ), the plural anchors  602 - 616  are preloaded within the shell  101 , and the wedge  702  and the cylindrical key  704  are preloaded with the introducer  901 . Also preloaded into the introducer  901  is the extender/connector  907  that interfaces the cylindrical key  704  to a driving/rotating tool (not shown), such as hexagonal screwdriver, to facilitate the cylindrical key&#39;s  704  advancement and rotation in the shell  101  via the driving/rotating end  806  of the cylindrical key  704 . More specifically, the access to the cylindrical key  704  may be extended by the extender/connector  907 , which may include a driving/rotating end and a mating end that fits the driving/rotating end  806  of the cylindrical key  704 . 
         [0043]    The handle portion  902  includes an opening  906  that receives protrusion  810  of the cylindrical key  704 , while the shell  101  receives the protrusion  808  via opening  122  between sidewall  102  and intermediate wall  146  (shown in  FIG. 1 ). Thus, the cylindrical key  704  temporarily secures the introducer  901  to the shell  101  to facilitate the delivery of the shell  101 , the anchors  602 - 616  concealed therein, the cylindrical key  704  and the extender/connector  907  into the disk space between the vertebrae (not shown). The swivel portion  904  includes a pivoting mechanism  905  that allows the swivel portion  904  to pivot via the pivoting mechanism  905  at about 90 degrees with respect to the handle portion  902 . Striking a hammer on the swivel portion  904  that is inline with respect to the handle portion  902  is used to deliver or advance the shell  101 , the plural concealed anchors  602 - 616  and the cylindrical key  706  into position within the disk space between the vertebrae. 
         [0044]    The swivel portion  904  includes an opening  903  that provides access to the preloaded wedge  702  and the cylindrical key  704  via the extender/connector  907 . More specifically, after positioning the shell  101  in a proper orientation within the disk space by using the introducer  901  in its inline position (e.g., the swivel portion  904  is extended in line with the handle portion  902  as shown in  FIG. 9 ), the swivel portion  904  is pivoted (not shown) via the pivoting mechanism  905  to expose the wedge  704  and the extender/connector  907  to the cylindrical key  704  via the opening  903 . The wedge  702  is advanced forward into the shell  101  to rotate the anchors  602 - 616  into their respective intermediately rotated positions. The cylindrical key  704  is then rotated about 90 degrees via the driving/rotating end  806  by using the extender/connector  907 , until protrusions  808 ,  810  coincide with portion  204  of the keyway  119  (shown in  FIG. 2 ), thereby unlocking the cylindrical key  704  from the introducer  901 . The cylindrical key  704  is advanced via the extender/connector  907  into the shell  101 , rotating the anchors  602 - 616  into their respective final extended positions. The cylindrical key  704  is then locked in the shell  101  by rotating the cylindrical key  704  via the extender/connector  907  back or forward so that the protrusions  808 ,  810  do not coincide with portion  204  of the keyway  119 . The wedge  702  and the extender/connector  907  are removed and the introducer  901  is removed from the disk space. Thus, the shell  101  is secured to the endplates of the vertebrae via the anchors  602 - 616  and the cylindrical key  704 . 
         [0045]      FIG. 10  is a perspective view  1000  of a cross-section of the second embodiment of a minimally invasive lateral intervertebral system  900  of  FIG. 9 . Perspective view  1000  illustrates cross-sections of the example introducer  901  that interfaces with the example shell  101  and the cylindrical key  704  to deliver and implant the shell  101 , the plural anchors  602 - 616  and the cylindrical key  704  (e.g., minimally invasive lateral intervertebral fixation device). The perspective view  1000  also illustrates the preloaded anchors  602 - 616  in the shell  101 , the preloaded wedge  702 , cylindrical key  704  and extender/connector  907  within the introducer  901 . The preloading of the foregoing elements via the shell  101  and the introducer  901  facilitates the minimally invasive lateral approach in delivering and securing the minimally invasive lateral intervertebral fixation device (e.g., shell  101 , anchors  602 - 616 , cylindrical key  704 ) within the disk space between vertebrae. 
         [0046]      FIG. 11  is an elevated side view  1100  of a minimally invasive lateral intervertebral fixation device  1102 . The minimally invasive lateral intervertebral fixation device  1102  is shown with plural anchors  602 - 616  of  FIG. 6  in an extended position in relation to the shell  101  of  FIG. 1 . The plural anchors  602 - 616  are locked via the cylindrical key  704 , which may be advanced via the driving/rotating end  806  and rotated via a hexagonal recess  1104 . In the extended and locked position, the base portions of the plural anchors  602 - 616  (e.g., base portion  402 ) are supported by the cylindrical key  704 . The inner surfaces  416  of the plural anchors  602 - 616  generally approximate the surfaces  110  or  112  to provide weight-bearing support for the endplates of the vertebrae. 
         [0047]      FIG. 12  is an elevated side view  1200  of the minimally invasive lateral intervertebral fixation device  1102  of  FIG. 11  with the plural example anchors  602 - 616  in a locked and an extended position in relation to the shell of  FIG. 1  and securing a top endplate  1204  of a vertebra  1202  of a spine (not shown). For clarity, the minimally invasive lateral intervertebral fixation device  1102  is shown securing only one vertebra. It is noted, however, that the minimally invasive lateral intervertebral fixation device  1102  is inserted into a disk space between plural vertebrae, one below and one on top of the minimally invasive lateral intervertebral fixation device  1102 , and secures the plural vertebrae via the respective anchors  602 - 608  and  610 - 616  and cylindrical key  704 . The minimally invasive lateral intervertebral fixation device  1102  is disposed approximately centrally within the disk space between the plural vertebrae. The vertebra  1202  includes a top endplate  1204 , a bottom endplate  1208  and a central portion  1206 . The endplates  1204 ,  1208  consist of cortical bone, which is much harder and denser than the cancellous bone of the central portion  1206 . Consequently, the respective anchors  602 - 608  and  610 - 616  hook and secure the respective endplates  1204  and  1208  of plural vertebrae. The inner surfaces  416  of the plural anchors  602 - 608  and  610 - 616  generally approximate the top surface  110  or the bottom surface  112  to provide weight-bearing support for the endplates of the vertebra. Because the shell  101  and the cylindrical key  704  are made of the same material (e.g., PEEK) and the inner surfaces  416  of the plural anchors  602 - 608  and  610 - 616  approximate the top and bottom surfaces  110 ,  112  of the shell  101 , the minimally invasive lateral intervertebral fixation device  1102  provides substantial weight-bearing capability and mitigates subsidence of the of the minimally invasive lateral intervertebral fixation device  1102  into the vertebrae. 
         [0048]    The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the disclosed embodiments. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the principles defined herein may be applied to other embodiments without departing from the scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope possible consistent with the principles and novel features as defined by the following claims.