Patent Publication Number: US-2023157842-A1

Title: Devices and methods for correcting vertebral misalignment

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. Pat. Application Serial No. 17/202,786 filed on Mar. 16, 2021 which is a continuation of Application of U.S. Pat. Application No. 16/129,842 filed on Sep. 13, 2018 (published as U.S. Pat. Pub. No. 2019-0015216), which is a continuation of U.S. Pat. Application No. 13/767,539 filed on Feb. 14, 2013, now U.S. 10,105,239, each of which are incorporated by reference herein in their entireties for all purposes. 
    
    
     FIELD OF THE INVENTION 
     Embodiments of the present disclosure relate generally to correcting misalignment of vertebral bodies comprising the spinal column. More particularly, embodiments of the present disclosure relate to stabilizing dislocated vertebral bodies to, among other things, correct spondylolisthesis and other spinal column injuries or deformities. 
     BACKGROUND 
     Spondylolisthesis is a medical condition in which one vertebral body slips (e.g., anteriorly) in relation to an adjacent vertebral body, usually in the lumbar region of the spine. This condition can cause symptoms that include pain in the lower back, thighs, and/or legs, muscle spasms, weakness, and/or tight hamstring muscles. In some cases, however, the presence of spondylolisthesis can be identified only by radiographic imaging (e.g., X-ray). 
     One solution for correcting spondylolisthesis and other similar conditions of vertebral dislocation may include reconstructive surgery and fusion of the affected vertebral body to an adjacent vertebral body. Vertebral fusion is generally accomplished by removing the native disc and then fixing an apparatus to and between the misaligned vertebrae. In addition to the stabilization and correction of spondylolisthesis, embodiments of the present disclosure may facilitate correction or treatment of other spinal conditions, including, but not limited to, stabilization of fractures, correction of spinal deformities (e.g. scoliosis and/or kyphosis), stabilization and correction of degenerative spinal lesions and narrow spinal canal, reconstruction after tumor resection, and secondary spinal surgery. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present disclosure relate to, among other things, correction of spondylolisthesis by movement of the vertebrae into better alignment while maintaining stabilization of the vertebrae in the new position. Further, embodiments of the present disclosure may be used to move one or more dislocated (e.g., slipped) vertebral bodies into a post-surgical position and keep the vertebrae in the post-surgical position during, e.g., ossification. Each of the embodiments disclosed herein may include one or more of the features described in connection with any of the other disclosed embodiments. 
     In one embodiment, a vertebral implant may include an assembly configured to be secured to a first vertebral body, wherein the assembly includes a frame made of a first material and at least one end plate made of a second material different than the first material; a reducing plate configured to be slidably received over the central portion, wherein the reducing plate is configured to be secured to a second vertebral body; and an actuator configured to move the reducing plate relative to the frame. 
     In another embodiment, a vertebral implant may include a frame assembly include a left lateral portion, a central portion, and a right lateral portion, wherein the left and right lateral portions define enlarged heads configured to receive fasteners therein for securing the frame assembly to a first vertebral body, and wherein the central portion defines a lumen therethrough; a reducing member configured to be slidably received over the central portion, wherein the reducing member includes an anterior portion and a plurality of plates extending posteriorly therefrom, wherein the plurality of plates define a channel therebetween, wherein the channel is configured to receive a portion of the central portion; and an actuator configured to control a position of the reducing member relative to the frame assembly. 
     In a further embodiment, a method of correcting vertebral misalignment may include positioning an implant within a space between two adjacent vertebral bodies, wherein the implant may include a frame assembly include a left lateral portion, a central portion, and a right lateral portion, wherein the left and right lateral portions define enlarged heads configured to receive fasteners therein for securing the frame assembly to a first vertebral body, and wherein the central portion defines a lumen therethrough; a reducing member configured to be slidably received over the central portion, wherein the reducing member includes an anterior portion and a plurality of plates extending posteriorly therefrom, wherein the plurality of plates define a channel therebetween, wherein the channel is configured to receive a portion of the central portion; and an actuator configured to control a position of the reducing member relative to the frame assembly. The method may further include securing the frame assembly to a first vertebral body of the two adjacent vertebral bodies; securing the reducing member to a second vertebral body of the two adjacent vertebral bodies, wherein the second vertebral body is disposed superiorly of the first vertebral body; rotating the actuator to move the second vertebral body relative to the first vertebral body; and securing the reducing member relative to the frame assembly. 
     In yet another embodiment, a method of correcting vertebral misalignment may include accessing adjacent vertebral bodies via an anterior-only approach; removing a native disc from in between the adjacent vertebral bodies to form an interbody disc space; roughening one or more surfaces of one or both of the adjacent vertebral bodies; positioning an implantable assembly within the interbody disc space. The implantable assembly may include a frame member having a substantially cylindrical central portion, wherein the frame member is configured to be secured to a first vertebral body of the adjacent vertebral bodies by a first fastener; a reducing member movably secured to the frame member, wherein the reducing member is configured to be slidably received over the cylindrical central portion, and wherein the reducing member is configured to be secured to a second vertebral body of the adjacent vertebral bodies by a second fastener; and an actuator for controlling a position of the reducing member relative to the frame member. The method may also include adjusting a position of one of the adjacent vertebral bodies relative to the other of the adjacent vertebral bodies. 
     In a further embodiment, a vertebral implant may include a head portion including a first counterbore, a second counterbore, a third counterbore, and a fourth counterbore; a plurality of planar longitudinal members extending away from the head portion, wherein the plurality of planar longitudinal members are spaced from one another to define a channel therebetween; and a plurality of endplates configured to be disposed on each of the plurality of planar longitudinal members. 
     It may be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the present disclosure and together with the description, serve to explain the principles of the disclosure. 
         FIG.  1 A  depicts an isometric view of an apparatus for correcting vertebral misalignment in a first configuration, in accordance with an embodiment of the present disclosure; 
         FIG.  1 B  depicts a top view of the apparatus of  FIG.  1 A ; 
         FIG.  1 C  depicts a side view of the apparatus of  FIG.  1 A ; 
         FIG.  1 D  depicts a bottom view of the apparatus of  FIG.  1 A ; 
         FIG.  2 A  depicts an isometric view of the apparatus of  FIG.  1 A  in a second configuration, in accordance with an embodiment of the present disclosure; 
         FIG.  2 B  depicts a top view of the apparatus of  FIG.  2 A ; 
         FIG.  3 A  depicts the apparatus of  FIG.  1 A  implanted between two vertebral bodies, in accordance with an embodiment of the present disclosure; 
         FIG.  3 B  depicts the apparatus of  FIG.  1 A  adjusted to be in the second configuration of  FIG.  2 A , in accordance with an embodiment of the present disclosure; 
         FIG.  4 A  depicts an apparatus for correcting misalignment of adjacent vertebral bodies, in accordance with a further embodiment of the present disclosure; 
         FIG.  4 B  depicts an apparatus for correcting misalignment of adjacent vertebral bodies, in accordance with another embodiment of the present disclosure; 
         FIG.  4 C  depicts an apparatus for correcting misalignment of adjacent vertebral bodies, in accordance with yet another embodiment of the present disclosure; 
         FIG.  4 D  depicts an apparatus for correcting misalignment of adjacent vertebral bodies, in accordance with a further embodiment of the present disclosure; 
         FIG.  4 E  depicts an apparatus for correcting misalignment of adjacent vertebral bodies, in accordance with another embodiment of the present disclosure; 
         FIG.  4 F  depicts an apparatus for correcting misalignment of adjacent vertebral bodies, in accordance with yet another embodiment of the present disclosure; 
         FIGS.  5 A- 5 B  depict an embodiment of using an apparatus of the present disclosure to reposition dislocated vertebral bodies; 
         FIG.  6 A  depicts an apparatus for correcting vertebral misalignment, in accordance with an embodiment of the present disclosure; 
         FIG.  6 B  depicts an exploded view of the apparatus of the  FIG.  6 A ; 
         FIG.  6 C  depicts a partially assembled view of the subcomponents of the apparatus of  FIG.  6 A ; and 
         FIGS.  7 A- 7 B  depict sagittal cross-sectional views of the apparatus of  FIG.  6 A  in expanded and contracted configurations, respectively. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the exemplary embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     It is understood that the exemplary devices and methods discussed below are described in connection with vertebral bodies, such as, e.g., the lumbar and sacral vertebral bodies. However, unless specifically noted, the disclosed embodiments are not limited to use in connection with vertebral bodies, or any particular vertebral bodies. Instead, the disclosed embodiments may have applicability in various parts of the body where it is desired to correct misalignment between adjacent structures. Moreover, the disclosed embodiments may be used in various procedures where the benefits of the described devices and methods are desired. 
     Turning now to  FIGS.  1 A- 1 D , there is depicted an exemplary embodiment of an intervertebral implant assembly  10 , in accordance with an embodiment of the present disclosure. As alluded to above, the implant assembly  10  may be used for, among other things, correcting misalignment of adjacent vertebral bodies, which may be commonly associated with, e.g., spondylolisthesis. The implant assembly  10  may include an outer member  20  and an inner member  50 . 
     The outer member  20  may be configured to define a frame having a substantially U-shaped configuration. The U-shaped configuration may define a cavity/opening  22  therein. As discussed in greater detail below, the outer member  20  may be configured to at least partially receive at least a portion of the inner member  50  within cavity  22 . The outer member  20  may include a first component  24 , which may be a frame or frame-like member. First component  24  may be configured to provide structural rigidity to outer member  20 . 
     In one embodiment, component  24  may include a substantially U-shaped configuration that defines cavity  22 . As shown in  FIG.  1 A , component  24  may include a first leg  26 , a second leg  28 , and a connecting leg  30 . Connecting leg  30  may define the base of the U-shaped configuration, with legs  26 ,  28  extending anteriorly therefrom. Connecting leg  30  may include substantially planar anterior  32  and posterior  34  (shown in  FIG.  1 B ) surfaces. Similarly, connecting leg  30  may include substantially planar superior  36  and inferior  38  (shown in  FIG.  1 D ) surfaces. In addition, some embodiments of superior and inferior surfaces  36 ,  38  may include a slant or taper extending away from the anterior surface  32  and narrowing toward opening/cavity  22 . That is, in some embodiments, portions of assembly  10  may include a tapering configuration. In such embodiments, therefore, a width of posterior surface  34  may be smaller than the width of anterior surface  32 . In other embodiments, however, the width of posterior surface  34  may be larger than the width of anterior surface  32 . In further embodiments, a width of the anterior surface  32  may be substantially similar to a width of the posterior surface  34 . 
     As noted above, first and second legs  26 ,  28  extend anteriorly away from connecting leg  30 . It is contemplated that legs  26 ,  28  may be substantially similar to one another. Indeed, in one embodiment, legs  26 ,  28  may be effectively mirror images of each other. Thus, for the purposes of efficiency, only first leg  26  will be described herein. However, those of ordinary skill will understand that leg  28  may include some or all of the features of first leg  26 . In addition, legs  26  and  28  do not necessarily have to be identical to one another. In fact, legs  26  and  28  may include differing configurations (not shown). 
     First leg  26  may include an extension portion  40  and a head portion  42 . Extension portion  40  may be integrally formed with connecting leg  30  and extending anteriorly therefrom. In some embodiments, however, extension portion  40  may be fixedly secured to connecting leg  30  by any suitable means known in the art. For example, extension portion  40  may be welded to connecting leg  30 . Extension portion  40  may include a substantially trapezoidal configuration. In other words, a transverse cross-sectional dimension may gradually increase along the length of extension portion  40 . Extension portion  40  may include a superior surface  44  and an inferior surface  46 . As discussed in greater detail below, both the superior  44  and inferior  46  surfaces may include geometrical features configured to promote gripping of tissue and/or bone surfaces. For example, the geometrical features may include pyramidal extensions  48  rising away from the respective superior  44  and inferior  46  surfaces. In another embodiment, the surfaces  44 ,  46  may include peaks, valleys, barbs, tines, a roughened surface, or any configuration suitable for promoting gripping of appropriate tissue and/or bone surfaces. 
     An anterior end of extension portion  40  may be integrally formed with head portion  42 . In some embodiments, however, head portion  42  may be fixedly secured to extension portion  40  by, e.g., welding. Head portion  42  may include a height larger than a height of connecting leg  30 . With particular reference to  FIG.  1 A , head portion  42  may be configured to extend laterally away from extension portion  40  in the direction away from cavity  22 . Furthermore, like superior  44  and inferior  46  surfaces of extension portion  40 , the superior  52  and inferior  54  surfaces of head portion  42  may include geometric features for aiding in the gripping of tissue or bone surfaces. In addition, the superior  52  and inferior  54  surfaces may include a stepped configuration, which allows head portion  42  to gradually increase in a height dimension in the anterior direction. Although the depicted embodiment includes three (3) steps, those of ordinary skill in the art will understand that any suitable number of steps may be provided to achieve the desired increase in height and rate of increase in height. 
     A posterior surface  56  of head portion  42  may be substantially planar with the exception of a one or more tabs  58  protruding posteriorly therefrom. Although the depicted embodiments illustrate only one tab  58  protruding from posterior surface  56 , those of ordinary skill in the art will understand that any suitable number of tabs  58  may protrude from the posterior surface  56 . Tab  58  may include any suitable dimension and/or configuration. As will be discussed in greater detail below, tab  58  may facilitate connection of first component  24  to second component  60 . Rather than including a protruding tab  58 , head portion  42  may include a recess (not shown) for receiving a correspondingly configured insert portion (not shown) extending from second component  60 . 
     A lateral surface, e.g., outer lateral surface  62  of head portion  42  may be substantially planar. In some embodiments, lateral surface  62  may include at least one geometric feature  64  for allowing a tool to grip or otherwise manipulate assembly  10 . Geometric feature  64  may include any suitable configuration corresponding to an appropriate tool. In one embodiment, geometric feature  64  may include a substantially rectangular notch having rounded corners. The notch may include a depth into the lateral surface  62  of head portion  42 . As shown in  FIG.  1 A , geometric feature  64  may be disposed relatively closer to posterior surface  56  than to anterior surface  66  of head portion  42 . 
     Anterior surface  66  of head portion  42  may be substantially planar. In some embodiments, anterior surface  66  may include at least one counterbore  68  configured to at least partially receive a head of a fastener, which will be described in greater detail below. Counterbore  68  may be in communication with a coaxial hole extending through head portion  42 , as shown in  FIG.  1 D . Counterbore  68  may be configured to facilitate guiding a fastener (e.g., bone screw  80  described in greater detail below) through head portion  42  at a desired angle. In an embodiment, counterbore  68  and its corresponding coaxial hole may be configured to guide the fastener into a vertebral body in a converging relationship relative to the fastener associated with head portion  42   a . The angle of insertion can be varied between 35 degrees from the cephalad caudal direction to 10 degrees medial-lateral. 
     Head portion  42  may include a second counterbore  70  disposed adjacent to counterbore  68 . Second counterbore  70  also may be in communication with another coaxial hole (not shown), which may not necessarily extend all the way through head portion  42 . Indeed, in the depicted embodiment, second counterbore  70  is in communication with a blind coaxial hole. Further, second counterbore  70  may be in communication with counterbore  68 . Stated another way, a portion of second counterbore  70  may open into counterbore  68  and vice versa, as shown in  FIG.  1 A . As will be explained in greater detail below, second counterbore  70  may include a fastener restricting mechanism  72 . Second counterbore  70  may include a depth sufficient to allow fastener restricting mechanism  72  to be disposed completely within second counterbore  70  or at least flush with anterior surface  66  of head portion  42 . 
     Fastener restricting mechanism  72  may be any suitable mechanism for preventing a fastener, such as, e.g., bone screw  80 , from becoming disengaged from the vertebral body to which it is secured. For example, in one embodiment, fastener restricting mechanism  72  may be configured to limit longitudinal displacement of bone screw  80 . Fastener restricting mechanism  72  may include a screw (e.g., a set screw) disposed in a hole that is coaxial with second counterbore  70 . In some embodiments, fastener restricting mechanism  72  may include a cam-style blocking mechanism. For example, the fastener restricting mechanism  72  may include a screw having a head having a greater width dimension than a remainder of the screw. The head of mechanism  72  may include a cutout that allows a head  82  of bone screw  80  to freely pass the head of mechanism  72  when the cutout is disposed in the path of travel of head  82 . However, when fastener restricting mechanism  72  is rotated, the cutout may be moved away from the path of travel of head  82  and a blocking portion of mechanism  72  may be disposed in the path of travel of head  82 , thereby preventing longitudinal movement of bone screw  80 . Also, as is known in the art, the head  82  of bone screw  80  may include a keyed opening  81 , which may be configured to receive a correspondingly-sized tool for rotating bone screw  80 . 
     As explained above, second leg  28  may include one or more features of leg  26 . Indeed, in some embodiments, second leg  28  may be an identical mirror image of first leg  26 . 
     In some embodiments, portions of first component  24  may be configured to promote bone tissue infiltration. For example, in one embodiment, the superior and inferior surfaces (or any other surfaces configured to be in contact with bony tissue) may include a porous configuration to allow bone ingrowth. In another embodiment, those surfaces of first component  24  that are intended to be in contact with bony tissue may include a suitable coating, such as, e.g., hydroxyapatite, for promoting bone tissue ingrowth into portions of first component  24 . 
     First component  24  may be fabricated via any method known in the art. For example, first component  24  (including first leg  26 , second leg  28 , and connecting leg  30 ) may be molded in a one-piece configuration. In another embodiment, portions of first component  24  may be discreetly fabricated, and then secured together by any suitable means, including, but not limited to, welding. 
     First component  24  may be fabricated from any suitable biocompatible material. For example, in one embodiment, all or a portion of first component  24  may be made of Titanium. Other suitable materials include, but are not limited to, stainless steel, nickel, silver, or any suitable alloy. 
     As alluded to above, outer member  20  may further include a second component  60 . As shown in  FIG.  1 A , for example, second component  60  may be disposed substantially about first component  24 . More particularly, second component  60  may extend from posterior surface  56  of head portion  42 , along first leg  26 , along connecting leg  30 , and along second leg  28  to the posterior surface  56   a  of second head portion  42 . In some embodiments, second component  60  may be formed of a one-piece configuration. In other embodiments, second component  60  may be formed of a plurality of discrete components secured to one another. 
     With continuing reference to  FIG.  1 A , the portions of second component  60  adjacent head portions  42 ,  42   a , may include an opening or a cutout  74  configured to receive tab  58  therein. Cutout  74  may include any suitable configuration corresponding to a configuration of tab  58 . In one embodiment, cutout  74  may be configured to retain tab  58  therein via a suitable interference or friction fit. In another embodiment, tab  58  may be retained within cutout  74  with the aid of an adhesive. In an even further embodiment, a mechanical fastener  76  may be used to retain tab  58  within cutout  74 . In those embodiments where a mechanical fastener  76  may be used, one of a superior or inferior surface of second component  60  may include an opening  78  for receiving the fastener  76 . The opening  78  may include a counterbore configured to completely receive a head of fastener  76  therein. The counterbore  78  may lead to a coaxial opening extending through second component  60  at least between the counterbore and cutout  74 . In such embodiments, tab  58  may include a corresponding opening or hole (not shown) for receiving a portion of fastener  76  therein. In addition, both the hole in tab  58  and the coaxial hole through second component  60  may include geometric features (e.g., internal screw threads) configured to interact with corresponding geometric features (e.g., external screw threads) on fastener  76  for retaining fastener, thereby retaining tab  58  within cutout  74 . 
     As shown in  FIG.  1 B , second component  60  may include first and second lateral portions  60   a ,  60   b  corresponding to head portions  42 ,  42   a . Anterior portions of lateral portions  60   a ,  60   b  may include width and height dimensions corresponding approximately to those of head portions  42 ,  42   a . In addition, as shown in  FIG.  1 A , lateral portions  60   a ,  60   b  may include a posteriorly tapering configuration. That is, a height of lateral portion  60   a ,  60   b  at, e.g., a location adjacent head portion  42  may be larger than a height at, e.g., a location farther away from head portion  42 . 
     The superior and/or inferior surfaces of lateral portions  60   a ,  60   b  may include one or more geometric configurations configured to promote frictional interaction with adjacent bone or tissue surfaces. For example, the superior and/or inferior surfaces may include a plurality of pyramid-like projections  69  and corresponding valleys. In other embodiments, the superior and/or inferior surfaces may include, but are not limited to, barbs, tines, hooks, a roughened surface, etc. In addition, or alternatively, the superior and/or inferior surfaces may include a suitable porous structure configured to promote bone ingrowth. In addition, the superior and/or inferior surfaces may include a coating for promoting bone ingrowth. In one embodiment, the coating may include hydroxyapatite. Of course, any portion of assembly  10  may include any suitable coating, including, but not limited to, coatings containing therapeutic, antibiotic, and/or anesthetic agents. 
     Lateral portions  60   a ,  60   b  may be connected to one another via central portion  60   c . Central portion  60   c  may be disposed adjacent connecting leg  30 . Central portion  60   c  may include width and height dimensions substantially similar to connecting leg  30 . In one embodiment, the superior  84  and anterior  86  surfaces of central portion  60   c  may include a tapering configuration. Further, although the depicted embodiments do not illustrate any geometric features on the surfaces of central portion  60   c , those of ordinary skill will readily recognize that one or more surfaces of central portion  60   c  may include any suitable geometric configurations and/or coatings. 
     Second component  60  may be made of any suitable biocompatible materials, including, but not limited to, thermoplastics, metals, composites, and/or alloys. In one embodiment, for example, second component  60  may be made of polyether ether ketone (PEEK). 
     With renewed reference to  FIG.  1 A , for example, inner surfaces of legs  26  and  28  may be substantially planar. In one embodiment, however, the inner surfaces of one or both of legs  26  and  28  may include a ledge or rail  88  disposed thereon. As will be discussed in greater detail below, rail  88  may be configured to slidably receive inner member  50 . In some embodiments, rail  88  may be integrally fabricated with the inner surfaces of legs  26  and  28 . In another embodiment, rail  88  may be secured to the inner surfaces of legs  26  and  28  via any suitable means. Although the depicted embodiment illustrates only one rail  88  on each of the inner surfaces of legs  26  and  28 , those of ordinary skill in the art will readily understand that any suitable number of rails  88  may be provided in accordance with the principles of the present disclosure. In some embodiments, instead of or in addition to a rail  88 , the inner surfaces of legs  26  and  28  may be formed with a groove  77  for receiving a corresponding projection  79  from inner member  50 . The groove  77  may be integrally formed within the surfaces of legs  26  and  28 , or the groove may be cut (by, e.g., a laser) after legs  26  and  28  are formed. Moreover, although the depicted embodiment illustrates that a rail  88  is provided on each of legs  26  and  28 , some embodiments may only include a single rail  88  provided on one of legs  26  and  28 . In further embodiments, one of legs  26  and  28  may include a rail  88 , and the other of legs  26  and  28  may include a groove  77  as discussed above. 
     In addition to a mechanism (e.g., rail  88 ) for slidably receiving inner member  50 , the inner surfaces of one or both of legs  26  and  28  may include a mechanism for retaining a position of inner member  50  relative to outer member  20 . The mechanism for retaining inner member  50  relative to outer member  20  may be any suitable mechanism known in the art. For example, in one embodiment, the inner surfaces of one or both of legs  26  and  28  may include a ratchet mechanism  90 , which will be discussed below in greater detail. In another embodiment, the mechanism may include one or more spring-loaded projections (not shown) configured to interact with a plurality of grooves or openings (not shown). The spring-loaded projections may be disposed on inner surfaces of legs  26  and  28 , and the grooves may be disposed on inner member  50 , and vice versa. 
     In some embodiments, the mechanism for retaining a position of inner member  50  relative to outer member  20  may be configured to allow only unidirectional movement of inner member  50  relative to outer member  20 . For example, ratchet mechanism  90  may comprise of plurality of directional teeth  92  disposed on an inner surface of one of legs  26  and  28 . In addition, one or more pawls or other suitable catch(es)  94  may be disposed on (e.g., extend from) inner member  50 . The positioning of the directional teeth  92  and catch(es)  94  may be reversed in some embodiments. In addition, the ratchet mechanism  90  may include multiple rows of directional teeth  92 . As will be explained in greater detail below, ratchet mechanism  90  may allow inner member  50  to be gradually and progressively advanced into opening  22 , while precluding inner member  50  from being withdrawn in the reverse direction. 
     With continued reference to  FIGS.  1 A- 1 D , inner member  50  may be configured to be at least partially received within opening  22  of outer member  20 . Inner member  50  may include an anterior portion  100  with a plurality of legs  102  extending posteriorly away from anterior portion  100 . In one embodiment, the entirety of inner member  50  may be configured to be received within opening  22 , such that anterior portion  100  is made flush with head portions  42 ,  42   a , as shown in  FIG.  2 A . For the purposes of efficiency, only one of the plurality of legs  102  will be described herein. However, those of ordinary skill in the art will understand that the other leg  102  may include any or all of the described features. Indeed, in one exemplary embodiment, the plurality of legs  102  may be substantially identical mirror images of each another. 
     Anterior portion  100  may include an anterior surface  103 . Anterior surface  103  may be substantially planar. In one embodiment, anterior surface  103  may include a first counterbore  104  and a second counterbore  106 . The first counterbore  104  may be in communication with a coaxial hole (not shown), and may be configured to receive and retain a fastener, such as, e.g., bone screw  80 , therein. For example, a portion of first counterbore  104  and or the coaxial hole may include geometric features (e.g., internal screw threads) configured to interact with geometric features (e.g., external screw threads) disposed on bone screw  80 . As with counterbore  68  described above, first counterbore  106  may be configured to facilitate guiding a fastener (described in greater detail below) through anterior portion  100  at a desired angle. 
     The second counterbore  106  may be disposed adjacent and in communication with first counterbore  104 . As described above, second counterbore  106  may include one or more features of counterbore  70 . For example, second counterbore  106  may be in communication with a coaxial hole (e.g., a blind coaxial hole) (not shown), and may be configured to receive and retain a fastener retaining mechanism  72  (described above) therein. 
     In addition, anterior portion  100  may be dimensioned so that the superior and/or inferior surfaces are substantially flush with the respective surfaces of head portions  42 ,  42   a , as shown in  FIG.  2 A , for example. 
     Legs  102  may extend posteriorly from a posterior surface of anterior portion  100 , so as to define a substantially U-shaped configuration. In one embodiment, legs  102  may be fabricated from a one-piece construction with anterior portion  100 . In another embodiment, one or both of legs  102  may be fixedly secured to a posterior surface of anterior portion  100 , via, e.g., welding or a suitable fastening mechanism, including, but not limited to, a mechanical fastener or an adhesive. Legs  102  may generally include a tapering configuration corresponding to associated portions (e.g., legs  26 ,  28 ) of outer member  20 . For example, legs  102  may decrease in height when moving in the posterior direction. 
     As alluded to above, one or both of legs  102  may include portions of ratchet mechanism  90 . For example, one or both of legs  102  may include either a plurality of directional teeth  92  or catches  94 . In the illustrated embodiments, legs  102  include a single catch  94  extending laterally away from legs  102 , as shown in  FIG.  1 B . The catch  94  may include a hook-like configuration. Catch  94  may be configured to deform out of and into engagement with successive teeth  92 . Accordingly, a portion of catch  94  may be elastic or spring-like. In some embodiments, legs  102  may include a plurality of catches  94 . The catch  94  may be configured to interact with directional teeth  92  to retain inner member  50  relative to outer member  20 . As explained above, catch  94  may be configured to allow unidirectional relative movement between outer member  20  and inner member  50 . That is, directional teeth  92  and catch  94 , collectively referred to as ratchet mechanism  90 , may be configured to only allow inner member  50  to move into opening  22 , but not out of it. 
     In addition, each of legs  102  may include an elastic or spring-like stabilizing member  87 . The stabilizing member  87  may assist in guiding inner member  50  as it slides relative to outer member  20 . In addition, stabilizing member  87  may be configured to exert tension against legs  26 ,  28 , respectively, to ensure inner member  50  remains centered with respect to opening  22 . Further, stabilizing member  87  may also act as a spring point for ratchet mechanism  90 , allowing for a smooth flexing of catch  94 . 
     The superior and/or inferior surfaces of inner member  50  may be configured to promote bone ingrowth. For example, one or more superior and/or inferior surfaces of inner member  50  may include a porous structure to facilitate tissue infiltration. In addition, the one or more superior and/or inferior surfaces of inner member  50  may include any suitable coating, such as, e.g., a coating of hydroxyapatite, a therapeutic agent, and/or an anesthetic. 
     The sides of inner member  50  may include one more slots and/or notches  110 , and/or projections  79 , which may be configured to allow inner member  50  to slide on rail  88  of outer member  20 . Of course, those of ordinary skill in the art will recognize that the exact design and configuration of the mechanism that allows inner member  50  to move relative to outer member  20  may vary among the many available options known in the art. The illustrated embodiments and configurations therefore are only for exemplary purposes. For example, as shown in  FIG.  1 A , each side of inner member  50  includes two notches  110 , at least one of which is configured to matingly receive rail  88 . In addition, a projection  79  may be configured to be received into a groove  77 . The notches  110  may be disposed along an entire side of inner member  50 , and may be disposed on an outer sidewall of legs  102 . In embodiments where the inner surfaces of legs  26  and  28  include multiple projections or rails, e.g., the outer sidewall of legs  102  would include corresponding geometric features as well. 
     With reference now to  FIGS.  2 A and  2 B , as discussed above, inner member  50  is configured to move relative outer member  20 , such that it may gradually move from the configuration depicted in  FIGS.  1 A- 1 D  to, e.g., the configuration depicted shown in  FIGS.  2 A- 2 B . As a result of ratchet mechanism  90 , however, inner member  50  may be positioned in any intermediate position between those shown in  FIGS.  1 A- 1 D  and  FIGS.  2 A- 2 B . As shown in  FIG.  2 A , inner member  50  may be dimensioned to be completely received within opening  22 , so that anterior surface  103  is substantially flush with the anterior surfaces of head portions  42 ,  42   a . As will be discussed below in greater detail, inner member  50  may be moved relative to outer member  20  by any suitable method. For example, in one embodiment, inner member  50  may be moved by driving its associated screw  80  into a vertebral body. In another embodiment, the inner member  50  may be pushed into opening  22  by, e.g., a tool, until inner member  50  is positioned in a desired location relative to outer member  20 . Subsequently, a screw  80  may be inserted into counterbore  104  and secured to a vertebral body, thereby securing inner member  50  relative to outer member  20 . 
     Furthermore, portions of inner member  50  and/or outer member  20  may be radiolucent or radiopaque as desired. In addition, assembly  10  may include any suitable radiopaque markings necessary to assist with visualizing assembly  10  within a patient’s body. 
     Turning now to  FIGS.  3 A- 3 B , an exemplary method for correcting misalignment of vertebral bodies in a patient’s spine is depicted and described herein. As shown in  FIG.  3 A , a first vertebral body VB 1  may have slipped forward and out of alignment relative to a second vertebral body VB 2  disposed below first vertebral body VB 1 . Such slippage may occur for any number of reasons, including, but not limited to, age-related degeneration, physical trauma, congenital birth defect, or stress fractures caused by, among other things, excessive hyperextension of the spine. 
     Prior to beginning a procedure to correct the misalignment between vertebral bodies VB 1  and VB 2 , a physician or other healthcare provider may manually move vertebral body VB 1  into correct alignment to gauge, among other things, the amount of correction needed and the appropriate positioning of assembly  10  relative to vertebral body VB 2 . To correct the aforementioned vertebral body misalignment, the physician or other healthcare provider may begin by accessing the targeted anatomical structures through any suitable approach known in the art. It is contemplated that the devices described herein may allow for correcting vertebral misalignment via a solely anterior approach. Once the physician accesses the targeted anatomical structures, he/she may begin by removing the native disk disposed in between of vertebral bodies VB 1  and VB 2 . Vertebral bodies VB 1  and VB 2  may include any vertebral bodies in a patient’s spine. In some cases, vertebral body VB 1  may include the Lumbar 5 (L5) vertebral body, and vertebral body VB 2  may include the Sacrum 1 (S1) vertebral body. The disk may be removed by any suitable procedure known in the art, including, but not limited to, a discectomy. In some instances, the physician may roughen adjacent surfaces on each of vertebral bodies VB 1  and VB 2  prior to positioning assembly  10  in the interbody disk space between vertebral bodies VB 1  and VB 2 . Assembly  10  may be implanted in a pre-assembled stated with inner member  50  connected to outer member  20 . Further, during the procedure, the assembly  10  may not be disassembled. As alluded to above, the procedure may be conducted via an anterior-only approach. That is, the assembly  10  may be implanted and manipulated from only an anterior side of the patient. 
     Once positioned appropriately on, e.g., vertebral body VB 2 , the physician may use a tool (not shown) to engage opening  81  on the associated screws  80  to drive screws  80  into vertebral body VB 2  at a predetermined angle, so as to securely fasten outer member  20  to vertebral body VB 2 . Prior to engaging screws  80 , however, if necessary, the physician may manipulate fastener restricting mechanism  72  to a configuration that allows screw heads  82  to pass by fastener restricting mechanism  72 . As shown in, e.g.,  FIG.  1 D , screws  80  may be inserted into vertebral body VB 2  in a converging relationship relative to one another. Once the screws  80  have properly secured outer member  20  to vertebral body VB 2 , the fastener restricting mechanism  72  may be manipulated again to prevent screws  80  from becoming disengaged. Next, in some embodiments, bone cement or another similar substance may be placed within opening  22  of outer member  20 . Subsequently, in one embodiment, inner member  50  may be manually pushed into cavity to effect the desired amount of correction necessary to correct the misalignment of vertebral bodies VB 1  and VB 2 . As noted above, inner member  50  may be gradually and step-by-step advanced into opening  22  as catch  94  passes each directional tooth  92 . In another embodiment, bone screw  80  associated with inner member  50  may be gradually advanced into vertebral body VB 1  until the desired level of correction is achieved, as shown in  FIG.  3 B . Once the desired level of correction is achieved, a fastener restricting mechanism  72  may be activated to prevent bone screw  80  of inner member  50  from becoming disengaged. 
     With reference now to  FIGS.  4 A- 4 F , there are depicted additional embodiments of devices for correcting misalignment of vertebral bodies, including, e.g., spondylolisthesis. Though the depicted embodiments contemplate treating spondylolisthesis via an anterior approach, those of ordinary skill in the art will understand that any suitable approach is contemplated within the principles of the present disclosure. As noted above, each of the various embodiments disclosed herein may include any of the features described in connection with the other embodiments. 
     With specific reference to  FIG.  4 A , there is depicted a first vertebral body VB  1  and a second vertebral body VB 2 . In the illustrated embodiment, first vertebral body VB 1  may be disposed above second vertebral body VB 2 . An embodiment of a device in accordance with the present disclosure may include an interbody spacer  400  configured to be implanted within the interbody disk space between vertebral bodies VB 1  and VB 2 . Spacer  400  may include any suitable configuration. In one embodiment, spacer  400  may include dimensions corresponding to first and second vertebral bodies VB 1  and VB 2 . In addition, spacer  400  may include a substantially solid component made of, e.g., PEEK. In other embodiments, spacer  400  may include a cage-like configuration with a substantially hollow interior. For example, spacer  400  may be made of a plurality of wires defining an enclosure. The wires, or any portion of spacer  400 , may be made of any suitable materials, including, e.g., titanium, nickel, stainless steel, or any alloys thereof. 
     In one embodiment, one or more of the superior and/or inferior surfaces of spacer  400  may include one or more geometric features configured to allow spacer  400  to grip adjacent bony surfaces of vertebral bodies VB 1  and VB 2 . For example, the superior and/or inferior surfaces may include projections, such as, e.g., barbs, tines, spikes, and/or screws. In a further embodiment, the superior and/or inferior portions of spacer  400  may be configured to promote bone ingrowth. For example, one or both of the superior and/or inferior surfaces of spacer  400  may include a porous portion. In another embodiment, one or both of the superior and/or inferior surfaces of spacer  400  may include a suitable coating, including, e.g., a coating of hydroxyapatite. Spacer  400  may also include any other suitable coating (e.g., antibiotic, antiseptic, anesthetic, or otherwise therapeutic) known in the art. Further, spacer  400  may be flexible and/or compressible. In other embodiments, spacer  400  may be substantially rigid. A portion of spacer  400  may be radiopaque while other portions remain radiolucent. For example, in embodiments where spacer  400  is made of PEEK, the spacer  400  may include one or more suitable radiopaque markers thereon. 
     In some embodiments, one or more dimensions of spacer  400  may be selectively adjustable. For example, a height, width, or diameter of spacer  400  may be adjusted to suit a particular patient’s anatomy. Spacer  400  may be adjusted by any means known in the art. In some embodiments, spacer  400  may be configured to expand and collapse. In such embodiments, spacer  400  may be expanded to desired dimensions. For example, spacer  400  may be an inflatable structure, which may be inflated until it expands to a desired dimension. In such cases, spacer  400  may be inflated with any suitable material. For example, spacer  400  may be inflated with a substance (e.g., an epoxy) configured to harden or cure once spacer  400  is inflated to a desired dimension. 
     Spacer  400  may include a passageway or channel  402  therethrough. Channel  402  may be formed by any suitable means known in the art. For example, spacer  400  may be molded with channel  402  therein. In another embodiment, channel  402  may be drilled or cut through spacer  400 . Although the depicted embodiment illustrates a single channel  402 , those of ordinary skill in the art will understand that spacer  400  may include any suitable number of channels  402 . Channel  402  may extend through spacer  400  in any suitable direction or at any suitable angle. For example, channel  402  may extend at an angle configured to allow a fastener inserted therethrough to bring vertebral bodies VB 1  and VB 2  closer together. In addition, the angle may also cause the vertebral bodies to move laterally relative to one another. In those embodiments where a plurality of channels  402  are provided, the plurality of channels  402  may extend parallel to one another or at an angle relative to one another. One or all of the plurality of the channels  402  may be configured to receive a fastener such as, e.g., elongate member  404 . Channel  402  may be preformed in spacer  400  prior to implantation. In some embodiments, however, channel  402  may be formed in spacer  400  after implantation. For example, a reamer (not shown) may be used to create channel  402 . Alternatively, channel  402  may be created by advancing elongate member  404  through spacer  400 . 
     With continued reference to  FIG.  4 A , the disclosed embodiment may further include an elongate member  404  inserted from vertebral body VB  1  through spacer  400  and into vertebral body VB 2 . In some embodiments, elongate member  404  may include a strut, rod, or screw. That is, the elongate member  404  may have any suitable configuration known in the art. Elongate member  404  may include one or more geometric features for retaining elongate member  404  within vertebral bodies VB 1  and VB 2 . Such features may include, e.g., screw threads and/or a screw head  408 . In addition, a distal end of elongate member  404  may be sharpened or may terminate in a pointed end. 
     Elongate member  404  may be made of any suitable materials, including, e.g., titanium, stainless steel, nickel, or any suitable alloys. In addition, elongate member  404  may include tissue, such as, e.g., an allograft. 
     In the embodiment shown in  FIG.  4 A , a portion of vertebral body VB  1  may be removed by, e.g., reaming. For example, a conventional reamer may be used to create a passageway into vertebral body VB  1 . Further, a cavity for accommodating screw head  408  may be also created in vertebral body VB 1 . In some embodiments, a passageway into vertebral body VB 2  may be also created. In addition, a thread cap (not shown) may be secured to a base of the passageway in vertebral body VB 2  for receiving elongate member  404 . 
     In use, elongate member  404  may be inserted into vertebral body VB 1 , through spacer  400 , and screwed into vertebral body VB 2  with or without the aid of a suitable thread cap. Doing so will cause spacer  400  to become compressed between vertebral bodies VB 1  and VB 2 , as indicated by arrows  401   a  and  401   b . Also, as a result of the angle of insertion of elongate member  404 , the vertebral bodies VB  1  and VB 2  may be moved laterally relative to one another to correct any misalignment caused by, e.g., spondylolisthesis, as shown by arrows  407   a  and  407   b . The degree of correction necessary may determine the depth elongate member  404  is inserted into vertebral body VB 2 . 
     With reference now to  FIG.  4 B , there is depicted another embodiment of a device for correcting vertebral body misalignment. The embodiment depicted in  FIG.  4 B  may include one or more features of the embodiment depicted in  FIG.  4 A . For example, the embodiment of  FIG.  4 B  may include a spacer  400  having a channel  402 , and an elongate member  410 . Elongate member  410  of  FIG.  4 B  may be substantially similar to the elongate member  404 . However, instead of a head  408 , elongate member  410  may include screw threads disposed on both ends thereof, with at least one of the ends terminating in a pointed end, while the other terminates in a blunt end. The screw threads  412  on a superior end of elongate member  410  may be configured to receive a nut  414  thereon for securing elongate member  410  to vertebral body VB  1 . Nut  414  may include a through hole or a blind hole (not shown) therein. In embodiments where elongate member  410  may be secured to a vertebral body (e.g., vertebral body VB 1 ) via nut  414 , the vertebral body may be further reamed to create a counterbore  411  for receiving nut  414 . As those in art will readily recognize, counterbore  414  may include a diameter large enough to completely accommodate nut  414  and the corresponding terminal end of elongate member  410  therein. 
     With reference to  FIG.  4 C , an angle of channel  402  through spacer  400 , or the depth elongate member  410  is inserted into vertebral body VB 2 , may cause a superior end of elongate member  410  to protrude out of a periphery of vertebral body VB 1 . In such cases, a cap  416  may be provided to protect anatomical structures (e.g., nerves, blood vessels, and the like) from damage caused by the superior end of elongate member  410  and/or an associated nut. Cap  416  may be any suitable structure configured for being disposed over an end of elongate member  410  to create a substantially atraumatic surface thereon. In one embodiment, cap  416  may define a cavity therein for placement over a superior end of elongate member  410 . The cavity may be configured to receive the end of elongate member  410  and any associated nut. For example, cap  416  may be a rigid or flexible member configured to be cemented or otherwise secured over the superior end of elongate member  410 . In a further embodiment, cap  416  may include a gel or paste-like substance configured to be applied about and over the superior end, and be molded or shaped to form an atraumatic external surface when dried or cured. The gel or paste-like substance may be configured to cure upon exposure to certain triggers, including, e.g., body chemistry and/or temperature. 
     As shown in  FIG.  4 D , e.g., an embodiment of a device for correcting vertebral misalignment may include lining a surface of counterbore  411  with a staple or plate  420 . Plate  420  may provide a rigid surface upon which nut  414  may rest. In addition, plate  420  may prevent rotation of nut  414  from further damaging the native structure of the vertebral body. Moreover, plate  420  may assist in preventing nut  414  from disengaging elongate member  410 . For example, plate  420  may include a catch (e.g., a projection) (not shown) configured to prevent nut  414  from reversing itself off of elongate member  410 . In one embodiment, the catch may include one or more features of the fastener restricting mechanism described above. 
     Plate  420  may include any suitable configuration. For example, in one embodiment, plate  420  may include a relatively small thickness. In addition, plate  420  may be made of any suitable material. For example, plate  420  may be made of a biocompatible metal, such as, e.g., titanium, stainless steel, nickel, nitinol, or any suitable alloy. In addition, plate  420  may be substantially malleable so as to allow plate  420  to be conformed to an inner surface of counterbore  411 . Further, the material of plate  420  may be configured to transition from a substantially flexible (e.g., foil-like) state to a substantially rigid state upon exposure to certain triggers, including, e.g., body chemistry and/or temperature. Further, plate  420  may include a substantially constant thickness, or may include one or more different thicknesses, as shown in, e.g.,  FIG.  4 E . 
     Plate  420  may be secured to the inside of counterbore  411  by any suitable method known in the art. For example, plate  420  may be adhesively secured to counterbore  411  by, e.g., bone cement. In another embodiment, one or more mechanical fasteners may be used to secure plate  420  to one or more portions of counterbore  411 . In some embodiments, a portion  421  of plate  420  may extend out of counterbore  411  and along an external wall of vertebral body VB 1 , for example. In such embodiments, portion  421  may facilitate anchoring plate  420  to the vertebral body. In addition, portion  421  may prevent damage to weakened portions of the vertebral body structure by, e.g., a tool rotating nut  414 . Further, although not shown, additional portions of plate  420  may extend out of counterbore  411  and along any external wall of vertebral body VB 1 . 
     Turning now to  FIG.  4 E , there is depicted yet another embodiment of a device for correcting spinal misalignment. The embodiment depicted in  FIG.  4 E  may include one or more of the features described in connection with the other embodiments discussed herein. The embodiment of  FIG.  4 E  includes an adjustable passageway or channel  403 . Channel  403  may be made adjustable by any suitable means known in the art. For example, structures may be selectively positioned within or about an opening of channel  403  to alter an angle of channel  403  relative to spacer  400 . In the embodiment of  FIG.  4 E , channel  403  may be formed in an insert  422  that is movable relative to a remainder of spacer  400 . Insert  422  may include any suitable configuration known in the art. Insert  422  may include a substantially spherical configuration configured to be movably disposed in an appropriately configured recess in spacer  400 . Insert  422  may be made of any suitable material capable of allowing insert  422  to move relative to spacer  400 . For example, insert  422  may be made of a plastic configured to minimize friction between insert  422  and spacer  400 . In addition, an outer surface of insert  422  and/or an inner surface of the cavity within which it is disposed may include a suitable lubricious coating. 
     Insert  422  may be manipulated to set an angle of channel  403  through spacer  400  by any suitable means. For example, prior to implanting spacer  400 , a physician may manually set a position of insert  422 . In another embodiment, insert  422  may be adjusted into position by elongate member  410  as it travels through spacer  400 . In an even further embodiment, a suitable tool may be employed to manipulate insert  422  in situ as desired. 
     Turning now to  FIG.  4 F , there is depicted yet another embodiment of a device for correcting vertebral misalignment. The embodiment of  FIG.  4 F  may include one or more features of the embodiment of  FIG.  4 E . In addition, the embodiment of  FIG.  4 E  may allow for using a tool  450  to, among other things, manipulate insert  422  and guide elongate member  410  therethrough. 
     As shown in  FIG.  4 F , tool  450  may include a first portion  452  and a second portion  454 . Tool  450  may function as a guide for orienting a cannula  460  for appropriate insertion of elongate member  410 . First portion  452  may be integrally formed with second portion  454 . In some embodiments, however, first portion  452  may be rigidly connected to second portion  454  by, e.g., welding. An end  453  of first portion  452  opposite to the connection with second portion  454  may be configured follow an angle of insert  422 . For example, end  453  may include a curved face  455  having an arc angle corresponding to an outer surface of insert  422 . End  453  may include any suitable configuration for following an angle of insert  422 . Thus, as insert  422  is manipulated to select a desired angle for channel  403 , guide  450  may be accordingly adjusted, thereby setting a corresponding angle for insertion of elongate member  410  via cannula  460 . As explained above, end  453  is configured to follow an angle of insert  422 . Consequently, first portion  452  and second portion  454  may be adjusted as insert  422  is adjusted. End  457  of second portion  454  may be configured to be removably secured to an insertion cannula  460 . Thus, as guide  450  is moved, cannula  460  may be accordingly oriented to correspond to the angle of channel  403 . 
     With reference now to  FIGS.  5 A- 5 B , a method of using one or more of the embodiments of  FIGS.  4 A- 4 F  is illustrated and described herein. As noted above, the methods and devices disclosed herein may be used to, among other things, correct misalignment of vertebral bodies, e.g., spondylolisthesis. Although the described method corrects vertebral misalignment via an anterior approach, those of ordinary skill in the art will understand that a posterior approach may be used additionally or alternatively. Further, although the described embodiments discuss moving a superior vertebral body relative to an inferior vertebral body, the inferior vertebral body may be moved additionally or alternatively. 
     With reference to  FIG.  5 A , an interbody device  500  is depicted between a superior vertebral body VB  1  and an inferior vertebral body VB 2 . In some cases, the superior vertebral body VB  1  may be the L5 vertebral body, and the inferior vertebral body may be the S1 vertebral body. As noted above, however, prior to positioning interbody device between vertebral bodies VB  1  and VB 2 , the native disk may be removed by any suitable procedure. The inferior surface of vertebral body VB  1  and the superior body of vertebral body VB 2  may be roughened to promote fusion (e.g., ossification) with interbody device  500 . To assist with fusion, interbody device  500  may include a plurality of geometric features  502  disposed on one or both of the superior and/or inferior surfaces of interbody device  500 . The geometric features  502  may include any suitable configuration and may include barbs, tines, spikes, screws, and the like. In some embodiments, a suitable adhesive (e.g., bone cement) may be used to fixedly connect the interbody device to the adjacent surfaces of one or more of vertebral bodies VB  1  and VB 2 . For example, bone cement may be used to secure interbody device  500  to the superior surface of vertebral body VB 2 . 
     The interbody device  500  may include a one-piece construction. In some embodiments, however, the interbody device  500  may include two components fixedly joined together. The components of interbody device  500  may be made of any suitable material including, but not limited to, titanium, stainless steel, PEEK, nickel, or any suitable alloys. Interbody device  500  may further include a channel  503  extending at an angle through interbody device. As well be explained in greater detail below, channel  503  may be configured to receive an elongate member, such as, e.g., a screw  504  therethrough. In some embodiments, an angle at which channel  503  extends through interbody device  500  may be adjustable. 
     Prior to inserting screw  504 , however, a passageway  506  may be created through vertebral body VB  1  via a suitable reamer. In some embodiments, a similar passageway may be created in vertebral body VB 2  as well. In addition, a counterbore  508  in communication with passageway  506  may be created to receive head  505  of screw  504  therein. The counterbore  508  may be created by any suitable means, including, e.g., reaming. In some embodiments, however, only counterbore  508  may be created. The passageway  506  may be created by screw  504  as it is being driven through vertebral body VB 1 . Next, a plate  510 , which may be similar to plate  420  discussed above, may be disposed in counterbore  508 . As shown in  FIG.  5 A , plate  510  may include a through opening in communication with passageway  506 . In addition, as shown in  FIG.  5 B , portions of plate  510  may extend out of counterbore  508  and adjacent one or more external walls of vertebral body VB 1 . Next, screw  504  may be advanced through vertebral body VB 1 , interbody device  500 , and into vertebral body VB 2 . As screw  504  is advanced and tightened, the angle of insertion of screw  504  (resulting from the angle of channel  503 ) may cause vertebral body VB  1  to move posteriorly and inferiorly relative to vertebral body VB 2 , thereby moving vertebral body VB  1  into proper alignment with vertebral body VB 2 . 
     Turning now to  FIGS.  6 A- 6 B , there is depicted another embodiment of a device assembly  600  for correcting misaligned vertebral bodies, in accordance with the present disclosure. Assembly  600  may include any of the features described in connection with the other embodiments disclosed herein. For example, assembly  600  may include any or all of the features of assembly  10  described above. Assembly  600  includes a frame member  602 . Frame member  602  may include any suitable configuration for disposal in the interbody disk space between two adjacent vertebral bodies, such as, e.g., the L5 and S1 vertebral bodies. Of course, frame member  602  may be configured for disposal between any other two adjacent vertebral bodies. 
     Frame member  602  includes a posterior end  601  and an anterior end  603 . In addition, frame member  602  includes a central section  604 , a right lateral section  606 , and a left lateral section  608 . The “right” and “left” designations are assigned when assembly  600  is oriented and disposed in the interbody disk space between two adjacent vertebral bodies, for example. 
     Central section  604  includes a longitudinal member  610  defining a lumen  612  therethrough. Lumen  612  may be in communication with an opening disposed in an anterior end face  617  of longitudinal member  610 . The anterior end face  617  may be configured to receive a friction ring  615  thereon, which will be described in greater detail below. In the depicted embodiment, longitudinal member  610  may include a substantially cylindrical configuration having flanges  614  extending laterally away therefrom. Those of ordinary skill will understand that longitudinal member  610  may not be limited to a cylindrical configuration. In fact, longitudinal member  610  may include any suitable configuration known in the art. Lumen  612  may be a substantially circular lumen configured, e.g., to receive a suitable fastener therein. However, lumen  612  may include any suitable configuration. Lumen  612  may extend an entire length of longitudinal member  610 . In some embodiments, however, lumen  612  may only extend along a portion of longitudinal member  610 . In some embodiments, lumen  612  may include suitable geometric features therein for interacting and retaining a fastener received therein. In one embodiment, the geometric features may include internal screw threads. Further, as can be seen in  FIGS.  6 A- 7 B , longitudinal member  610  may include a through hole  616  extending from a superior external surface of longitudinal member  610  through lumen  612  and to an inferior external surface of longitudinal member  610 . Through hole  616  is utilized in the peening process for the central actuator  700  or longitudinal member  610 . Once the actuator  700  is threaded into through hole  698 , a portion of the male threads are deformed via through hole  616  thereby preventing the back out of the longitudinal member from the reducing plate  670 . Further, both longitudinal member  610  and lumen  612  may include substantially constant cross-sectional diameters. However, those of ordinary skill in the art will understand that the diameters of either longitudinal member  610  or lumen  612  may vary along the lengths thereof. For example, the diameters of one or both of longitudinal member  610  and lumen  612  may reduce when moving posteriorly from anterior end  603 . 
     Flanges  614  may be disposed adjacent a central longitudinal axis of lumen  612 . As shown in  FIG.  6 A , e.g., the transition from the substantially cylindrical outer surface of longitudinal member  610  to flanges  614  may be substantially smooth. In addition, each of flanges  614  may be integrally formed with longitudinal member  610 . However, in some embodiments, flanges  614  may be secured to longitudinal member  610  by, e.g., welding. Flanges  614  may include a generally rectangular cross-sectional configuration. However, one or both of flanges  614  may include any suitable configuration. In addition, the configuration of flanges  614  may not be identical to one another. For example, a left flange  614  may include a rectangular cross-sectional configuration, while the right flange may include a trapezoidal configuration (not shown). 
     Central section  604  may further include a posterior portion  618 . Posterior portion  618  may extend posteriorly from longitudinal member  610 . In addition, posterior portion  618  may extend farther in the superior direction than both of flanges  614  and longitudinal member  610 . Posterior portion  618  may also extend farther in the inferior direction than both of flanges  614  and longitudinal member  610 . Further, one or both of anterior surface  620  and inferior surface (not shown) of posterior portion  618  may be slanted to provide posterior portion  618  with a tapered configuration. Still further, a posterior surface (not shown) of posterior portion  618  may be substantially planar. 
     Central section  604  may be integrally formed with one or both of right lateral section  606  and left lateral section  608 . However, in some embodiments, the right and left lateral sections  606 ,  608  may be secured to central section  604  by any suitable means known in the art, including, e.g., welding. 
     With reference primarily to  FIG.  6 B , the right and left lateral sections  606 ,  608  may include substantially similar features. Indeed, the right and left lateral sections  606 ,  608  may be effectively mirror images of one another. For the purposes of efficiency, therefore, only right lateral section  606  will be described herein. However, those of ordinary skill in the art will understand that the right and left lateral sections  606 ,  608  also may include differing configurations (not shown). 
     Originating from approximately the location of the interface between posterior portion  618  and longitudinal member 610/flanges  614 , an extension member  622  may extend laterally away from central section  604 . As shown in  FIG.  6 B , extension member  622  may first extend laterally away from central section  604  and then curve to extend in the anterior direction. That is, extension member  622  may include a first portion  622   a  extending substantially perpendicularly to longitudinal member  610 , and a second portion  622   b  extending substantially parallel to central section  604 . First and second portions  622   a  and  622   b  may be connected by a central portion  622   c . Central portion  622   c  may be curved, as shown in  FIG.  6 B . However, central portion  622   c  may be effectively eliminated and first and second portions  622   a  and  622   b  may be joined by a right angle elbow (not shown). As can be seen in  FIG.  6 B , e.g., extension member  622  and longitudinal member  610  may define a plurality of through openings  605  therebetween. The openings  605  may be configured to receive bone cement therein during an implantation procedure. 
     Extension member  622  may include a substantially planar internal surface  623 . In addition, extension member  622  may include a curved external surface  625 . However, those of ordinary skill will understand that any suitable configuration may be employed for internal and external surfaces  623 ,  625 . Further, extension member  622  may include substantially planar superior and inferior surfaces. However, in some embodiments, the superior and inferior surfaces of extension member  622  may include suitable geometric configurations for receiving and retaining an endplate, as discussed in greater detail below. As shown in  FIG.  6 B , first portion  622   a  may include a hole  624  for facilitating retention of the aforementioned endplate. Hole  624  may include suitable geometric configurations for retaining a fastener therein. In one embodiment, hole  624  may include internal threads (not shown) configured to cooperate with a screw (not shown). 
     Second portion  622   b  of extension member  622  may include one or more geometric features to assist with retaining the aforementioned endplates. In one embodiment, one or both of the superior and/or inferior surfaces of second portion  622   b  may include a rib  626 . Rib  626  may include any suitable configuration known in the art. For example, rib  626  may include a rounded projection extending away from the respecting superior/inferior surfaces. In some embodiments, rib  626  may include a length along a substantial portion of second portion  622   b . However, rib  626  may not necessarily extend the full length of second portion  622   b . 
     An anterior end portion of extension member  622  may be integrally formed with an enlarged head portion  628 . Head portion  628  may include any of the features described above in connection with head portions  42 ,  42   a . For example, in one embodiment, a lateral face of each portion  628  may include a geometric feature  630  substantially similar to geometric feature  64  described above. In particular, geometric feature  630  may include a notch for allowing a tool (not shown) to grip and manipulate assembly  600 . Further, superior and inferior surfaces of head portion  628  may include one or more geometric features  632  configured to increase friction between assembly  600  and adjacent bony surfaces. The geometric features  632  may include a plurality of pyramid-like projections and corresponding valleys. In other embodiments, the superior and/or inferior surfaces may include, but are not limited to, barbs, tines, hooks, etc. In addition, or alternatively, the superior and/or inferior surfaces may include a suitable porous structure configured to promote bone ingrowth. Further, the superior and/or inferior surfaces may include a coating for promoting bone ingrowth. In one embodiment, the coating may include hydroxyapatite. Of course, any portion of assembly  600  may include any suitable coating, including, but not limited to, coatings containing therapeutic, antibiotic, and/or anesthetic agents. 
     The anterior surface of head portion  628  may define at least two counterbores  634 ,  636 . Counterbore  634  may be in communication with a coaxial hole extending through head portion  628  at an angle relative to a longitudinal axis (not shown) of central section  604  (e.g., longitudinal member  610 ). Counterbore  634  may be substantially spherical, and configured to receive a spherical head of a fastener (described below in greater detail) therein. In one embodiment, counterbore  634  and its associated coaxial hole may be configured to guide the received fastener at an angle in the inferior direction away from frame member  602 . In addition, the counterbore  634  and its associated coaxial hole may be configured to guide the received fastener toward a central vertical axis (not shown) of frame member  602 . Thus, the fasteners received in the two depicted head portions  628  may be disposed in a converging relationship relative to one another. As described below, the fasteners received in head portions  628  may include suitable bone screws  638 . 
     Counterbore  636  may be relatively smaller in diameter than counterbore  634 . In addition, counterbore  636  may be in communication with a blind coaxial hole (not shown). Counterbore  636  may be configured to receive therein a set screw  640  including a threaded portion  640   a  and a head portion  640   b . Head portion  640   b  may be configured to include a cam-style blocking mechanism, as described above. Indeed, set screw  640  may be substantially similar to fastener restricting mechanism  72 . More particularly, head portion  640   b  may include a cut-out portion  640   c  configured to allow bone screw  638  to pass by set screw  640  when cut-out portion  640   c  is disposed in the travel path of bone screw  638 . However, if set screw  640  is rotated to move cut-out portion  640   c  out of the travel path of bone screw  638 , a portion of head portion  640   b  may abut a head of bone screw  638 , thereby restricting its longitudinal movement. Those of ordinary skill will readily understand that any suitable mechanism for preventing bone screw  638  from reversing itself out of engagement may be utilized in accordance with the principles of the present disclosure. 
     Head portions  628  may be connected to an anterior end of central section  604  via central connections  639 . Central connections  639  may include any suitable configuration for supporting head portions  628 . For example, central connections  639  may include substantially planar anterior surfaces  641 , which may or may not be disposed flush with anterior surface  617 . Indeed, in some instances, anterior surfaces  641  may be raised (by, e.g., a dimension corresponding to a thickness of friction ring  615 ) relative to anterior surface  617  to provide a seat for friction ring  615 . Further, the inferior  646  surfaces of central connections  639  may include suitable geometric configurations for increasing friction relative to an adjacent bony surface, as described herein. With reference to  FIG.  6 B , anterior surfaces  617 , anterior surfaces  641 , and lateral surfaces of head portions  628  may define a cavity dimensioned for receiving an anterior head portion  672  of a reducing plate  670  therein, as described in greater detail below. 
     With continuing reference to  FIG.  6 B , each extension member  622  may be configured to receive an end plate  642  thereon. End plate  642  may include any suitable configuration for being disposed about extension member  622 . End plate  642  may include a first portion  642   a , a second portion  642   b , and a third portion  642   c  connecting the first and second portions  642   a ,  642   b . First, second, and third portions  642   a ,  642   b , and  642   c  may be formed integrally with one another. In other embodiments, however, first, second, and third portions  642   a ,  642   b , and  642   c  may be fixedly secured to one another by any suitable means known in the art. 
     First portion  642   a  may be configured to be received on first portion  622   a  of extension portion  622 . Accordingly, first portion  642   a  may include an internal channel  644  having internal geometry corresponding to an external geometry of first portion  622   a . The channel  644  may be configured to extend from a first terminal end face of end plate  642  to a second terminal end face of end plate  642 . In addition, channel  644  may be configured to receive extension member  622  therein via an opening  645  in an external wall of end plate  642 . Like channel  644 , opening  645   also may be configured to extend from a first terminal end face of end plate  642  to a second terminal end face of end plate  642 . In one embodiment, end plate  642  may be substantially flexible such that it may open in a clam-like manner, thereby enlarging opening  645  so that extension member  622 , and rib  626 , may be received in channel  644 . Further, a depth of channel  644  and opening  645  may be dimensioned such that when end plate  642  is disposed about extension member  622 , the respective surfaces of end plate  642  disposed above and below opening  645  are flush with surface  623  of extension member  622 . 
     First portion  642   a  may be dimensioned such that its superior and inferior surfaces are flush with respective surfaces of posterior portion  618 . For example, the superior and inferior surfaces of first portion  642   a  may include a slant or taper similar to the slant/taper of surface  620 . First portion  642   a  may also include a hole  650  configured to receive a fastener (e.g., a set screw) for fixedly securing end plate  642  to extension member  622 . 
     Like first portion  642   a , second and third portions  642   b ,  642   c  may be configured to be disposed about second and third portions  622   b ,  622   c  of extension member  622 . As explained above, channel  644  may include a suitable internal geometry for cooperating with an external geometry of extension member  622 . Thus, the portion of channel  644  in second portion  642   b  may include cutouts for accommodating one or more rib(s)  626 . In addition, as shown in  FIGS.  6 A- 6 B , end plate  642  may be configured to progressively increase in height from a posterior portion to an anterior portion, such that its anterior end may be substantially similar to a posterior end face of head portion  628 . Further, the superior and inferior surfaces of end plate  642  may include any suitable geometric configurations (e.g., rows of directional teeth, barbs, pyramids, etc.) configured to increase friction between end plate  642  and an adjacent bony surface. 
     End plate  642  may be fabricated via any suitable method known in the art. For example, end plate  642  may be molded or extruded. In addition, end plate  642  may be made of any suitable material. In one embodiment, end plate  642  may be made of a suitable organic polymer thermoplastic, such as, e.g., PEEK. In addition, one or more surfaces of end plate  642  may be configured to promote bone ingrowth. For example, superior and/or inferior surfaces of end plate  642  may include a porous structure to facilitate tissue infiltration. In addition, surfaces of end plate  642  may include any suitable coating, including, but not limited to, hydroxyapatite and/or coatings containing therapeutic, antibiotic, and/or antiseptic agents. 
     With continuing reference to  FIGS.  6 B and  6 C , e.g., assembly  600  may further include a reducing plate  670 . Reducing plate  670  may include an anterior head portion  672 . Anterior head portion  672  may include any suitable configuration. For example, anterior head portion  672  may be dimensioned to be received in the cavity defined by anterior surfaces  617 , anterior surfaces  641 , and lateral surfaces of head portions  628  described above, such that an anterior-most surface of reducing plate  670  may be substantially flush with respective surfaces of head portions  628  when reducing plate  670  is received in the aforementioned cavity. 
     Reducing plate  670  may define a mechanism for being received slidingly on longitudinal member  610 . For example, in one embodiment, reducing plate  670  may include a plurality of extension plates extending posteriorly from a posterior surface of anterior head portion  672 . The plurality of plates may include an inferior extension plate  674  and a superior extension plate  676 . Although only two extension plates  674 ,  676  are depicted, those of ordinary skill in the art will understand that any suitable number of extension plates  674 ,  676  may be provided. Extension plates  674 ,  676  may be spaced from one another to define a channel  678  therebetween. In some embodiments, channel  678  may be a closed channel (not shown). In such embodiments, lateral edges of extension plates  674 ,  676  may be joined together by, e.g., a wall (not shown). However, in the depicted embodiment, channel  678  is depicted as a channel having open side walls. The channel  678  may include a geometry corresponding to an outer geometry of longitudinal member  610  and flanges  614  so that reducing plate  670  may be slidably received on longitudinal member  610 , as shown in  FIG.  6 A . In addition, extension plates  674 ,  676  may include a length such that posterior-most surfaces of extension plates  674 ,  676  abut anterior surfaces of posterior portion  618  when anterior head portion  672  is fully received within the cavity defined by anterior surfaces  617 , anterior surfaces  641 , and lateral surfaces of head portions  628  described above. 
     The inferior surface  702  of inferior extension plate  674  may be configured to receive an end plate  706  thereon. Accordingly, surface  702  may include one or more geometric features configured to retain end plate  704  on surface  702 . In one embodiment, end plate  704  may be slid onto surface  702 . Accordingly, surface  702  may include a central raised portion  707  flanked by a stepped portion on either side. The central raised portion may define a rail along which end plate  704  may slide. The superior surface (not shown) of superior extension plate  676  may include features similar to those of surface  702 . 
     End plates  706  may be configured to be received on extension plates  674 ,  676 . End plates  706  may include any suitable configuration. Further, the configuration of each end plate  706  may be substantially similar. Accordingly, for the purposes of efficiency, only one end plate  706  will be described hereafter. In one embodiment, end plate  706  may be formed of a one-piece construction by, e.g., molding or extrusion. Further, end plate  706  may be formed of any suitable material, including, e.g., a suitable organic polymer thermoplastic, such as, e.g., PEEK. In addition, end plate  706  may include a generally tapering configuration. That is, as shown in  FIG.  6 B , a thickness of a posterior portion of end plate  706  may be smaller than a thickness of an anterior portion of end plate  706 . An outer side of end plate  706  may include a plurality of suitable geometric features configured to increase friction between end plate  706  and adjacent bony surfaces. The geometric features may include, e.g., projections, teeth, barbs, tines, spikes, and the like. For example, as shown in  FIG.  6 B , end plate  706  may include a plurality of rows of teeth. 
     An inner side of end plate  706  may define a groove  708  for being disposed about central portion  707 , so that end plate  706  may be received thereon. Accordingly, groove  708  may be appropriately dimensioned and configured. In one embodiment, groove  708  may include a substantially T-shaped configuration. That is, as shown in  FIG.  6 B , e.g., sides of groove  708  may extend into side walls of end plate  706  to define a portion of groove  708  being covered by overhang  708   b . Further, overhang  708   b  may be configured to be received in appropriately configured recesses on either side of central portion  707  so as to frictionally retain end plate  706  on extension members  674 ,  676 . 
     An anterior-most surface  680  of anterior head portion  672  may include a plurality of counterbores therein. For example, as shown in  FIG.  6 C , surface  680  may include four counterbores  682 ,  684 ,  686 , and  688 , each of which may be in communication with one another. Counterbores  682  and  684  may be substantially similar to each other and therefore will be described together. 
     Counterbores  682  and  684  may be in communication with respective coaxial holes (not shown) extending through anterior head portion  672 . Counterbores  682  and  684  and/or their respective coaxial holes may include suitable geometric features (e.g., internal screw threads) for retaining a suitable fastener (e.g., a bone screw  690 ) therein. Counterbores  682  and  684  may be substantially spherical in configuration so as to at least partially accommodate spherical heads  692  of bone screws  690 . Those of ordinary skill in the art will understand that any suitable fasteners may be used in place of bone screws  690 . In one embodiment, counterbores  682 ,  684  and their respective coaxial holes may be configured to guide bone screws  690  received therein in a superior direction at an angle relative to a longitudinal axis (not shown) of lumen  612 . In addition, counterbores  682 ,  684  and their respective coaxial holes may be configured to guide bone screws  690  received therein away from a central vertical axis (not shown) of frame member  602 . Thus, the fasteners received in counterbores  682  and  684  may be disposed in a diverging relationship relative to one another. In other embodiments, the fasteners may be disposed in a converging relationship relative to one another. 
     Counterbore  686  may be in communication with a coaxial through hole  698  (shown in  FIGS.  7 A- 7 B ). When reducing plate  670  is received over longitudinal member  610 , counterbore  688  and hole  698  may be in communication with lumen  612  for collectively receiving actuator  700  therein. One or both of counterbore  686  and through hole  698  may include geometric features (e.g., internal screw threads) for retaining actuator  700  therein. Further, as shown in  FIG.  6 A , counterbore  686  may be dimensioned to completely receive a head  700   a  of actuator  700 . As will be described in greater detail below, actuator  700  may be used to position reducing plate  670  relative to frame member  602 , so as to correct vertebral misalignment. 
     Counterbore  688  may be in communication with a coaxial blind hole  696  (shown in  FIGS.  7 A- 7 B ) for receiving a set screw  694  incorporating a plurality of the cam-style blocking mechanisms described above. The coaxial blind hole  696  may include suitable geometric features (e.g., internal screw threads) for retaining set screw  694  therein. Those of ordinary skill will readily understand that instead of set screw  694 , any suitable fastener restricting mechanism may be used in accordance with the principles of the present disclosure. Set screw  694  may include any of the features of fastening restricting mechanism  72  described above. Further, it is contemplated that set screw  694  may be configured to simultaneously restrict one or more of bone screws  690  and actuator  700  (discussed below in greater detail) from longitudinal travel. For example, in one embodiment, a head  694   a  of screw  694  may include a plurality of cutouts  694   c . As explained above, cutouts  694   c  may allow the heads of screws  690  and/or actuator  700  to pass head  694   a  of screw  694  when the cutouts  694   c  are positioned in the path of travel of screws  690  and/or actuator  700 , respectively. However, when cutouts  694   c  are moved out of the path of travel of screws  690  and/or actuator  700 , a portion of head  694   a  may interfere with the heads of screws  690  and/or actuator  700 , thereby restricting their longitudinal movement. Cutouts  694   c  may be moved into and out of the travel paths by rotating screw  694  within hole  696  via, e.g., any suitable tool known in the art. 
     Actuator  700  may be any suitable actuator known in the art. For example, actuator  700  may be a threaded bolt or screw including a head  700   a  having an opening  700   b  therein for allowing a tool to selectively rotate actuator  700 . Actuator  700  may also include a shaft  700   c  extending away from head  700   a  from a side of head  700   a  opposite to opening  700   b . The shaft  700   c  may include suitable geometric features (e.g., internal screw threads) for retaining actuator  700  in, e.g., lumen  612 . As shown in  FIGS.  7 A- 7 B , actuator head  700   a  may be received in counterbore  688 . In addition, shaft  700   c  may be received through hole  798  so that it may extend between extension plates  674 ,  676 , through an opening  619  in friction ring  615  and into lumen  612 . 
     Friction ring  615  may include any suitable structure configured to threadingly receive shaft  700   c  of actuator  700 . In some embodiments, friction ring  615  may be made of a suitable organic polymer thermoplastic, such as, e.g., PEEK. Friction ring  615  may be formed by any suitable process known in the art, including, e.g., molding, machining, or extrusion. As noted above, friction ring  615  may include an opening  619  corresponding to lumen  612 . In addition, friction ring  615  may be configured to be disposed adjacent surface  617  of longitudinal member  610 . In one embodiment, friction ring  615  may be made integrally with surface  617 . In another embodiment, friction ring  615  may be secured to surface  617  by, e.g., a suitable adhesive. 
     With reference now to  FIG.  6 B , an inferior surface  720  of anterior head portion may include an opening  722  in communication with a slot. The slot may be in communication with counterbore  688 . In one embodiment, opening  722  may be configured to receive therein a blocking plate  730 . Blocking plate  730  may include a substantially square or rectangular configuration. However, one side of blocking plate  730  may include a geometric feature  732  configured to surround and engage head  700   a  of actuator  700 . Geometric feature  732  may be configured to engage head  700   a  in the manner a wrench may engage the head of a nut, as will be appreciated by those of ordinary skill in the art. Blocking plate  730  may be made of any suitable material known in the art, including, but not limited to, titanium, stainless steel, nickel, and/or any suitable alloys. Further, blocking plate  730  may be dimensioned such that when geometric feature  732  engages with head  700   a , blocking plate  730  is received completely within opening  722 . Further, blocking plate  730  may be secured within opening  722  and its associated slot by any means known in the art. For example, a suitable adhesive (not shown) may be used to fix blocking plate  730  into opening  722 . 
     Furthermore, portions of assembly  600  may be radiolucent or radiopaque as desired. In addition, assembly  600  may include any suitable radiopaque markings necessary to assist with visualizing assembly  600  within a patient’s body. 
     Assembly  600  may be used to correct misalignment of adjacent vertebral bodies (e.g., the L5 and S1 vertebral bodies), including, but not limited to, spondylolisthesis. Assembly  600  may be pre-assembled with reducing plate  670  thereon prior to implantation. Prior to implanting assembly  600  within a patient, however, a patient’s native disc may be first removed by, e.g., a discectomy procedure. Next, the surfaces of the vertebral body immediately adjacent the interbody disk space may be roughened, as is known in the art. Subsequently, frame member  602  may be positioned in the interbody disk space. Prior to positioning frame member  602 , however, a physician or other healthcare provider may manually manipulate the dislocated vertebral bodies into proper alignment so as to identify an appropriate positioning of frame member  602  relative to, e.g., an inferior vertebral body. Once appropriately positioned, screws  640  may be rotated so that cutouts  640   c  are positioned in the path of travel of bone screws  638 , and bone screws  638  may be inserted into counterbores  634  to fasten frame member  602  to an inferior vertebral body. Screws  640  may be once again rotated to move cutouts  640   c  out of the path of travel of screws  638 , so that a remaining portion of a head of screw  640  may engage the heads of screw  638  to retain them in position. 
     Next, screw  694  may be manipulated to dispose cutouts  694   c  in the path of travel of bone screws  690 . Subsequently, bone screws  694  may be advanced into counterbores  682  and  684  and into a superior vertebral body to secure reducing plate  670  to the superior vertebral body. Then, screw  694  may be manipulated to move cutouts  694   c  out of the path of travel of screws  690 , so that a remaining portion of head  694   a  may engage the heads  692  of screws  690  to retain them in position. Head  694   a  may also function to restrict longitudinal movement of actuator  700 . 
     Subsequently, in some embodiments, bone cement may be disposed in openings  605 , as desired. Next, any displacement between the superior and inferior vertebral bodies may be corrected by gradually turning actuator  700  to move reducing plate  670  in the posterior direction over longitudinal member  610 . Once the desired amount of correction is achieved, actuator  700  may be fixed in place so that a position of reducing plate  670  is fixed relative to frame member  602 . Actuator  700  may be fixed in place my manipulating screw  694  so that, in addition to restricting movement of screws  690 , screw  694  also restricts further movement of actuator  700 . Further, blocking plate  730  may be inserted into and secured (via, e.g., an adhesive) within opening  722 , such that feature  732  engages actuator head  700   a  and prevents it from rotating. Any cement inserted into openings  605  may be allowed to cured and the procedure may be completed as customary in the art. 
     While principles of the present disclosure are described herein with reference to illustrative embodiments for particular applications, it should be understood that the disclosure is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, embodiments, and substitution of equivalents all fall within the scope of the embodiments described herein. Accordingly, the invention is not to be considered as limited by the foregoing description.