Patent Publication Number: US-2018028329-A1

Title: Acif cage, cage system and method

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to medical devices, and more specifically it relates to intervertebral and intradiscal devices, systems, and methods for deployment within a body of a patient. 
     BACKGROUND OF THE DISCLOSURE 
     In mammals, the spinal (or vertebral) column is one of the most important parts. The spinal column provides the main support necessary for mammals to stand, bend, and twist. 
     In humans, the spinal column is generally formed by individual interlocking vertebrae, which are classified into five segments, including (from head to tail) a cervical segment (vertebrae C1-C7), a thoracic segment (vertebrae T1-T12), a lumbar segment (vertebrae L1-L5), a sacrum segment (vertebrae S1-S5), and coccyx segment (vertebrate Co1-Co5). The cervical segment forms the neck, supports the head and neck, and allows for nodding, shaking and other movements of the head. The thoracic segment attaches to ribs to form the ribcage. The lumbar segment carries most of the weight of the upper body and provides a stable center of gravity during movement. The sacrum and coccyx make up the back walls of the pelvis. 
     Intervertebral discs are located between each of the movable vertebra. Each intervertebral disc typically includes a thick outer layer called the disc annulus, which includes a crisscrossing fibrous structure, and a disc nucleus, which is a soft gel-like structure located at the center of the disc. The intervertebral discs function to absorb force and allow for pivotal movement of adjacent vertebra with respect to each other. 
     In the vertebral column, the vertebrae increase in size as they progress from the cervical segment to the sacrum segment, becoming smaller in the coccyx. At maturity, the five sacral vertebrae typically fuse into one large bone, the sacrum, with no intervertebral discs. The last three to five coccygeal vertebrae (typically four) form the coccyx (or tailbone). Like the sacrum, the coccyx does not have any intervertebral discs. 
     Each vertebra is an irregular bone that varies in size according to its placement in the spinal column, spinal loading, posture and pathology. While the basic configuration of vertebrae varies, every vertebra has a body that consists of a large anterior middle portion called the centrum and a posterior vertebral arch called the neural arch. The upper and lower surfaces of the vertebra body give attachment to intervertebral discs. The posterior part of a vertebra forms a vertebral arch that typically consists of two pedicles, two laminae, and seven processes. The laminae give attachment to the ligament flava, and the pedicles have a shape that forms vertebral notches to form the intervertebral foramina when the vertebrae articulate. The foramina are the entry and exit passageways for spinal nerves. The body of the vertebra and the vertical arch form the vertebral foramen, which is a large, central opening that accommodates the spinal canal that encloses and protects the spinal cord. 
     The body of each vertebra is composed of cancellous bone that is covered by a thin coating of cortical bone. The cancellous bone is a spongy type of osseous tissue, and the cortical bone is a hard and dense type of osseous tissue. The vertebral arch and processes have thicker coverings of cortical bone. 
     The upper and lower surfaces of the vertebra body are flattened and rough. These surfaces are the vertebral endplates that are in direct contact with the intervertebral discs. The endplates are formed from a thickened layer of cancellous bone, with the top layer being denser. The endplates contain adjacent discs and evenly spread applied loads. The endplates also provide anchorage for the collagen fibers of the disc. 
       FIG. 1  shows a portion of a patient&#39;s spinal column  2 , including vertebrae  4  and intervertebral discs  6 . As noted earlier, each disc  6  forms a fibrocartilaginous joint between adjacent vertebrae  4  so as to allow relative movement between adjacent vertebrae  4 . Beyond enabling relative motion between adjacent vertebrae  4 , each disc  6  acts as a shock absorber for the spinal column  2 . 
     As noted earlier, each disc  6  comprises a fibrous exterior surrounding an inner gel-like center which cooperate to distribute pressure evenly across each disc  6 , thereby preventing the development of stress concentrations that might otherwise damage and/or impair vertebrae  4  of spinal column  2 . Discs  6  are, however, subject to various injuries and/or disorders which may interfere with a disc&#39;s ability to adequately distribute pressure and protect vertebrae  4 . For example, disc herniation, degeneration, and infection of discs  6  may result in insufficient disc thickness and/or support to absorb and/or distribute forces imparted to spinal column  2 . Disc degeneration, for example, may result when the inner gel-like center begins to dehydrate, which may result in a degenerated disc  8  having decreased thickness. This decreased thickness may limit the ability of degenerated disc  8  to absorb shock which, if left untreated, may result in pain and/or vertebral injury. 
     While pain medication, physical therapy, and other non-operative conditions may alleviate some symptoms, such interventions may not be sufficient for every patient. Accordingly, various procedures have been developed to surgically improve patient quality of life via abatement of pain and/or discomfort. Such procedures may include, discectomy and fusion procedures, such as, for example, anterior cervical interbody fusion (ACIF), anterior lumbar interbody fusion (ALIF), direct lateral interbody fusion (DLIF) (also known as XLIF), posterior lumbar interbody fusion (PLIF), and transforaminal lumbar interbody fusion (TLIF). During a discectomy, all or a portion of a damaged disc (for example, degenerated disc  8 , shown in  FIG. 1 ), is removed via an incision, typically under X-ray guidance. 
     Following the discectomy procedure, a medical professional may determine an appropriate size of an interbody device  10  (shown in  FIG. 2 ) via one or more distractors and/or trials of various sizes. Each trial and/or distractor may be forcibly inserted between adjacent vertebrae  4 . Upon determination of an appropriate size, one or more of an ACIF, ALIF, DLIF, PLIF, and/or TLIF may be performed by placing an appropriate interbody device  10  (such as, for example, a cage, a spacer, a block) between adjacent vertebrae  4  in the space formed by the removed degenerated disc  8 . Placement of such interbody devices  10  within spinal column  2  may prevent spaces between adjacent vertebrae  4  from collapsing, thereby preventing adjacent vertebrae  4  from resting immediately on top of one another and inducing fracture of vertebra  4 , impingement of the spinal cord, and/or pain. Additionally, such interbody devices  10  may facilitate fusion between adjacent vertebrae  4  by stabilizing adjacent vertebrae  4  relative to one another. Accordingly, as shown in  FIG. 2 , such interbody devices  10  often may include one or more bone screws  12  extending through interbody device  10  and into adjacent vertebrae  4 . 
     Often, following the removal of the distractor and/or trial, a medical professional must prepare one or more bores or holes in a vertebra  4  intended to receive the bone screws  12 . Such holes may be formed with the aid of a separate drill guide positioned proximate or abutting vertebra  4  and inserting a drill therethrough. Alternatively, such holes may be formed free hand, without the use of a drill guide. Further, since spinal column  2  is subject to dynamic forces, often changing with each slight movement of the patient, such screw(s)  12  have a tendency to back out (for example, unscrew) and/or dislodge from interbody device  10 , thereby limiting interbody device&#39;s  10  ability to stabilize adjacent vertebrae  4 , and consequently, promote fusion. Additionally, it screw(s)  12  back out and/or dislodge from the interbody device  10 , they may inadvertently contact, damage, and/or irritate surrounding tissue. Further, interbody device  10  is commonly comprised of a radiopaque material so as to be visible in situ via x-ray and other similar imaging modalities. However, such materials may impede sagittal and/or coronal visibility, thereby preventing visual confirmation of placement and post-operative fusion. 
     Furthermore, while all metal titanium interbody devices  10  are good for bone ingrowth, they are radio-opaque and, thus, not good for monitoring bony fusion. 
     Thus, there remains a need for improved interbody devices, associated systems, and methodologies related thereto. 
     SUMMARY OF THE DISCLOSURE 
     Accordingly, one aspect of the present disclosure provides a cage structure that can be made of different materials and textures. The cage structure may include various end surface textures with enhanced bone ingrowth while allowing for monitoring bony fusion. 
     According to an aspect of the present disclosure, an intervertebral cage structure is provided that comprises: a main body comprising a first surface and a second surface located opposite to the first surface; a plate disposed on the first surface of the main body; and an opening formed in the main body and extending from the first surface to the second surface located opposite the first surface, wherein the plate comprises a surface pattern having at least one of a symmetrical geometric pattern and an asymmetrical geometric pattern. The intervertebral cage structure may comprise a second plate disposed on the second surface of the main body. The main body may comprise Polyether Ether Ketone (PEEK). The plate may comprise titanium or a titanium alloy. 
     The main body may further comprise a plurality of lateral surfaces extending between the first and second surfaces; and one or more holes extending from one of the plurality of lateral surfaces towards the opening. The main body may further comprise an inner surface surrounding the opening. The inner surface may comprise a bulged portion surrounding a portion of the one or more holes. 
     The intervertebral cage structure may comprise a pin hole extending from the plate to the main body, and a pin that inserts into the pin hole. 
     The main body may further comprise one or more slots, and the plate may comprise one or more tabs that insert into the plurality of slots of the main body to secure the first plate to the main body. The plate may comprise a cutout that renders the plate compressible. 
     The intervertebral cage structure may comprise a shell main body, wherein the shell main body may be configured to receive and substantially encapsulate the main body. The shell main body may comprise a clam shape that includes said plate and the second plate, wherein said plate and the second plate are connected by a bridge portion. The main body may comprise at least one of a metal, PEEK, silicon and allograft. 
     According to another aspect of the disclosure, an intervertebral cage structure is provided that comprises: a shell main body having a clam shape and comprising a bridge portion and wing portions extending from the bridge portion; first and second surface layers disposed on the first and second wing portions; and an opening formed in the main body and extending from the first surface layer to the second surface layer. At least one of the first surface layer and the second surface layer may comprise at least one of a symmetrical geometric pattern and an asymmetrical geometric pattern. The shell main body may comprise PEEK and at least one of the first and second surface layers may comprise titanium or a titanium alloy. 
     The intervertebral cage structure may comprise an insertion. The insertion may be disposed between the first and second wing portions of the main body, wherein the opening may extend from the first surface layer to the second surface layer via the insertion. The insertion may comprise at least one of a metal, PEEK, silicon or allograft. 
     The intervertebral cage structure may comprise: a plurality of lateral surfaces extending between the first and second wing portions; and one or more holes extending from one of the plurality of lateral surfaces toward the opening. 
     The intervertebral cage structure may further comprise an inner surface surrounding the opening and having a bulged wall portion surrounding a portion of the one or more holes. 
     The intervertebral cage structure may include a slot and a guide that engages and guides the slot as the insertion is installed in the shell main body. 
     The intervertebral cage structure may further comprise: a plurality of lateral surfaces; and one or more screw holes extending from one of the plurality of lateral surfaces to the opening. 
     The intervertebral cage structure may further comprise first and second ears extending from the first and second wing portions, extending outwardly from each other, the first and second ears comprising one or more screw holes. 
     The surface pattern of the intervertebral cage structure may comprise first and second protrusions adjacent each other with a gap therebetween, wherein the first and second protrusions have an undercut at a lower portion thereof, wherein superior surfaces of the first and second protrusions may have different shapes, and wherein at least one of the first and second protrusions may have a pocket formed at the bottom surface thereof. 
     According to a further aspect of the disclosure, an intervertebral cage structure is provided that comprises a surface configured to contact a vertebra, the surface comprising first and second protrusions adjacent each other with a gap formed therebetween, the first and second protrusions having an undercut formed at a lower portion thereof. The superior surfaces of the first and second protrusions have different shapes. At least one of the first and second protrusions may have a pocket formed on the surface thereof. 
     Additional features, advantages, and embodiments of the disclosure may be set forth or apparent from consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that both the foregoing summary of the disclosure and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the disclosure as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the disclosure, are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the detailed description serve to explain the principles of the disclosure. No attempt is made to show structural details of the disclosure in more detail than may be necessary for a fundamental understanding of the disclosure and the various ways in which it may be practiced. In the drawings: 
         FIG. 1  illustrates a portion of a patient&#39;s spinal column; 
         FIG. 2  illustrates an interbody device positioned within the patient&#39;s spinal column constructed according to the principles of the disclosure; 
         FIG. 3A  illustrates a perspective view of an example of a cage structure that is constructed according to the principles of the disclosure; 
         FIG. 3B  illustrates another view of the cage structure illustrated in  FIG. 3A ; 
         FIG. 4A  illustrates an exploded view of the cage structure illustrated in  FIGS. 3A and 3B ; 
         FIG. 4B  illustrates an example of an implant tool that may be used to install the cage structure; 
         FIG. 5A  illustrates a perspective view of another example of a cage structure that is constructed according to the principles of the disclosure; 
         FIG. 5B  illustrates another view of the cage structure illustrated in  FIG. 5A ; 
         FIG. 5C  illustrates a superior (or inferior) view of the cage structure illustrated in  FIGS. 5A and 5B ; 
         FIG. 5D  illustrates an anterior view of the cage structure illustrated in  FIGS. 5A and 5B ; 
         FIG. 5E  illustrates a lateral view of the cage structure illustrated in  FIGS. 5A and 5B ; 
         FIG. 5F  illustrates a posterior view of the cage structure illustrated in  FIGS. 5A and 5B ; 
         FIG. 5G  illustrates a perspective anterior view of another example of a cage structure that is constructed according to the principles of the disclosure; 
         FIG. 6  illustrates an exploded view of the cage structure illustrated in  FIGS. 5A and 5B ; 
         FIG. 7A  illustrates an enlarged cut view of an example of a surface pattern of the cage structure illustrated in  FIG. 5A  (or  FIG. 3A , or  FIG. 5G ), constructed according to the principles of the disclosure; 
         FIG. 7B  illustrates an enlarge cut view of another example of a surface pattern of the cage structure illustrated in  FIG. 5A  (or  FIG. 3A , or  FIG. 5G ), constructed according to the principles of the disclosure; 
         FIG. 8A  illustrates a perspective anterior view of an example of a shell, constructed according to the principles of the disclosure; 
         FIG. 8B  illustrates a lateral view of the shell illustrated in  FIG. 8A ; 
         FIG. 8C  illustrates a perspective anterior view of another example of a shell, constructed according to the principles of the disclosure; 
         FIG. 8D  illustrates a lateral view of a further example of a shell, constructed according to the principles of the disclosure; 
         FIGS. 9A and 9B  illustrate anterior and lateral views of an example of a shell of the cage structure illustrated in  FIG. 5A ; 
         FIG. 10A  illustrates an exploded view of another example of a cage structure that is constructed according to the principles of the disclosure; 
         FIG. 10B  illustrates another view of the cage structure illustrated in  FIG. 10A ; 
         FIG. 10C  illustrates an exploded view of a further example of a cage structure that is constructed according to the principles of the disclosure; 
         FIG. 10D  illustrates another example of an insertion, constructed according to the principles of the disclosure; 
         FIGS. 10E and 10F  illustrate perspective anterior and lateral views, respectively, of another example of a cage structure constructed according to the principles of the disclosure; 
         FIG. 11A  illustrates an example of another cage structure, constructed according to the principles of the disclosure; and 
         FIG. 11B  illustrates the cage structure shown in  FIG. 11A , which is inserted between two adjoining vertebrae. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     The disclosure and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and examples that are described and/or illustrated in the accompanying drawings and detailed in the following description. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale, and features of one embodiment may be employed with other embodiments as the skilled artisan would recognize, even if not explicitly stated herein. Descriptions of well-known components and processing techniques may be omitted so as to not unnecessarily obscure the embodiments of the disclosure. The examples used herein are intended merely to facilitate an understanding of ways in which the disclosure may be practiced and to further enable those of skill in the art to practice the embodiments of the disclosure. Accordingly, the examples and embodiments herein should not be construed as limiting the scope of the disclosure. Moreover, it is noted that like reference numerals represent similar parts throughout the several views of the drawings. 
     The terms “including,” “comprising” and variations thereof, as used in this disclosure, mean “including, but not limited to,” unless expressly specified otherwise. 
     The terms “a,” “an,” and “the,” as used in this disclosure, mean “one or more,” unless expressly specified otherwise. 
     Devices that are in communication with each other need not be in continuous communication with each other, unless expressly specified otherwise. In addition, devices that are in direct contact with each other may contact each other directly or indirectly through one or more intermediary articles or devices. The device(s) disclosed herein may be made of a material such as, for example, a polymer, a metal, an alloy, or the like. For instance, the device(s) may be made of Polyether Ether Ketone (PEEK), titanium, a titanium alloy, or the like, or a combination of the foregoing. The material may be formed by a process such as, for example, an active reductive process of a metal (e.g., titanium or titanium alloy) to increase the amount of nanoscaled texture to device surface(s), so as to increase promotion of bone growth and fusion. 
     Although process steps, method steps, or the like, may be described in a sequential order, such processes and methods may be configured in alternate orders. In other words, any sequence or order of steps that may be described does not necessarily indicate a requirement that the steps be performed in that order. The steps of the processes or methods described herein may be performed in any order practical. Further, some steps may be performed simultaneously. 
     When a single device or article is described herein, it will be readily apparent that more than one device or article may be used in place of a single device or article. Similarly, where more than one device or article is described herein, it will be readily apparent that a single device or article may be used in place of the more than one device or article. The functionality or the features of a device or article may be alternatively embodied by one or more other devices or articles which are not explicitly described as having such functionality or features. 
       FIGS. 3A-4A  illustrate various views of a cage structure  100  that is constructed according to the principles of the disclosure, with  FIG. 3A  illustrating a perspective view of a cage structure  100 ;  FIG. 3B  illustrating another view of the cage structure  100 ; and  FIG. 4A  illustrating an exploded view of the cage structure  100 . The cage structure  100  may be constructed as one, two, three, or more parts. The cage structure  100  may be made of a material such as, for example, a polymer, a metal, an alloy, or the like. For instance, the cage structure  100  may be made of PEEK, titanium, a titanium alloy, or the like. The surfaces of the cage structure  100  may be formed to increase the amount of nanoscaled texture to increase promotion of bone growth and fusion in the implant area, wherein the formation may include forming a surface by, for example, an active reductive process of, e.g., titanium or titanium alloy. 
     Referring to  FIGS. 3A and 3B , in an embodiment of the cage structure  100  that has only one part (such as, e.g., shown in  FIG. 5G ), the cage structure  100  may comprise only the main body  110 . In this embodiment, the main body  110  may be formed as a single piece with a first main surface  102  on one side of the main body  110  (as seen in  FIGS. 3A and 3B ) and a second (opposite) main surface (not shown) on the other side of the main body  110 . The cage structure  100  may be implanted standalone or with a supplementary fixation device such as, for example, a plate (e.g., anterior cervical plate), a bone fastener(s), and/or the like. 
     Referring to  FIGS. 3A-4A  concurrently, in an embodiment of the cage structure  100  that has two or more parts, the cage structure  100  may include the main body  110  and one or more plates  150 A (and/or  150 B). The cage structure  100 , which may have the first main surface  102  and the second main surface (not shown) located opposite to the first main surface  102 , may directly contact two adjacent vertebrae, respectively, when the cage structure  100  is inserted therebetween. The first main surface  102  may be provided on the plate  150 A (or  150 B). The second main surface (not shown) may be provided on the plate  150 B (or  150 A). 
     In the cage structure  100 , the first main surface  102  may include a surface pattern such as, for example, the surface pattern shown in  FIG. 7A or 7B  and described in detail below, or any other pattern that may assist in capturing and retaining blood, tissue, bone graft, or the like, to promote bone growth or fusion. The second main surface (not shown) may have the same or a different surface pattern as the first main surface  102 . The surface pattern may include, for example, sharp teeth on the surface to ensure primary stability and prevent migration of the cage structure  100 . The surface pattern may be configured (e.g., as shown in  FIG. 7A or 7B ) to promote integration and bone ongrowth and ingrowth within the roughened surface for good stability. 
     The surface pattern may be provided on any surface area, including that of a cage structure (e.g., cage structure  100 ), where bone cells can attach and grow, including, for example, external sagittal walls, external coronal walls (front and/or back), and the like. The surface pattern may be provided to any cage shape or form with, or without supplementary fixation features, including, for example, cages shapes/forms configured for ACIF, PLIF, TLIF, DLIF, OLIF, VBR, and the like. 
     The cage structure  100  may be configured to have a shape in a horizontal plane in the form of, for example, a rectangle, a trapezoid, a square, a pentagon, a circle, an oval, a hexagon, or any other shape that may be appropriate for a particular application, as understood by those skilled in the art. The cage structure  100  may be formed to substantially match the shape and/or size of the space between the adjacent vertebrae, as well as the shape and size of the vertebrae surfaces (e.g., vertebra  4  shown in  FIG. 2 ) that contact the first main surface  102  and opposing second main surface (not shown) of the cage structure  100 , when the cage structure  100  is implanted. The cage structure  100  may have a substantially wedge-shaped design to accommodate endplate shape variances. In the vertical plane (i.e., the plane perpendicular to the horizontal plane), the cage structure  100  may have different heights for the anterior and posterior portions of the cage structure  100 , so as to properly fill the space between the adjacent vertebrae. 
     The cage structure  100  may include a plurality of side wall surfaces  104  that may extend between the first main surface  102  and the second main surface (not shown). The side wall surfaces  104  and the first and second main surfaces may form the outer shape of the cage structure  100 . The plurality of side wall surfaces  104  may include, for example, a posterior wall surface  104 A, an anterior wall surface  104 B, and a pair of lateral (or side) wall surfaces  104 C located opposite each other. 
     The cage structure  100  may include an opening  105 . The opening  105  may be formed in or near the center portion of the cage structure  105 . The opening  105  may extend between the superior and inferior directions of the cage structure  100 , extending from the first main surface  102  to the second main surface (not shown). The opening  105  may be defined and laterally surrounded by inner wall surface(s)  106  of the cage structure  100 . The opening  105  may form a chamber, such as, for example, a graft chamber that is configured to receive, for example, blood, tissue, bone, bone graft and the like, to promote bone growth or fusion. The inner wall surfaces  106  may have a surface pattern (not shown) that may help in retaining blood, tissue, bone graft, etc., in the graft chamber. 
     The cage structure  100  may include one or more openings or windows (not shown), such as, for example, window(s)  299  shown in  FIG. 50 . The window(s) may be formed in the lateral, posterior and/or anterior walls. Such windows may remain empty and/or may be filled with radiolucent material such as tissue grafts as will be described in further detail below. The windows may enable a medical professional to view and/or determine the level of post-operative fusion between cage structure  100  and patient bone and/or tissue. The cage structure body may define any appropriate arrangement, number, and configuration of windows. As seen in the example in  FIG. 5G , for example, the cage structure  100  may include a pair of windows  299  on each lateral side. Each window may be generally quadrilateral (e.g., square, rectangular, or trapezoidal). In some arrangements, a radiolucent structure, such as a graft containment sheath, may be disposed along one or more portions of cage structure  100 . Indeed, such graft containment sheaths may substantially fill or encompass window. Accordingly, when the cage structure  100  is placed between two adjacent vertebrae  4  (shown in  FIG. 1 ) under X-ray vision, the window remains radiolucent such that fusion within and/or through window may be observed. 
     As seen in  FIGS. 3B and 4A , the cage structure  100  may include one or more holes (or openings), such as, for example, a hole  108 A and a hole or recessed portion  108 B. Alternatively (or additionally), the cage structure  100  may include fastening holes (not shown) that may be configured to receive one or more bone fasteners (e.g., bone screws  12  shown in  FIG. 2 ) to secure the cage structure  100  to adjacent vertebra. In this regard, the fastening holes (not shown) may be angled so as to guide the bone fasteners toward and into the adjacent vertebrae.  FIG. 2  shows an example of fastening holes formed in an implantable device and angled so as to guide the bone screws  12  toward and into adjacent vertebrae  4 . 
       FIG. 4B  shows an example of an implant tool  400  that may be used to install the cage structure  100  in a spinal column of a patient. The implant tool  400  includes a handle  410 , a shaft  420 , and a contact head  430 . The handle  410  includes an engaging member  415  that is connected to or integrally formed with an internal shaft (not shown) that has a threaded end  432 . The internal shaft (not shown) may be housed in the shaft  420 . The threaded end  432  of the internal shaft may protrude from the contact head  430 , as seen in  FIG. 4B . The contact head  430  may include an orientation guide  434  (such as, for example, an orientation peg). The orientation guide  434  may be integrally formed with the contact head  430 . 
     Referring to  FIGS. 3A-4A  concurrently, the cage structure  100  (with or without a plating device (not shown)) may be configured for use in, for example, anterior approach and disectomy applications. For instance, after a surgical area is cleaned on a patient, an incision made, muscle tissue and/or organs moved to the side(s), and other common surgical procedures carried out, a disc may be incised, removed, and the space prepared for implanting of the cage structure  100 . The bone surfaces and edges on the adjacent vertebrae may be carefully contoured, as appropriate. 
     Following a discectomy procedure, a medical professional may determine an appropriate size of the cage structure  100  by selecting an appropriately dimensioned cage structure  100  and an appropriately dimensioned plating device (not shown), if applicable, which may be selectable based on, for example, height, width, depth, and the like. Upon selecting the appropriate cage structure  100  (and plating device, if applicable), one or more of an ACIF, ALIF, PLIF, TLIF, DLIF, OLIF, VBR, or the like may be performed by placing the cage structure  100  between adjacent vertebrae  4  in the space formed by the removed degenerated disc. Placement of the cage structure  100  within the spinal column may prevent spaces between adjacent vertebrae  4  from collapsing, thereby preventing adjacent vertebrae from resting immediately on top of one another and inducing fracture of vertebra  4 , impingement of the spinal cord, and/or pain. Additionally, such cage structures  100  may facilitate fusion (e.g., bone to grow together) between adjacent vertebrae  4  by stabilizing adjacent vertebrae  4  relative to one another and promoting bone ingrowth. 
     Referring to  FIGS. 3A-4B , the implant tool  400  may be securely connected to the cage structure  100  by aligning the threaded end  432  and the orientation guide  434  with the holes  108 A and  108 B, respectively. The threaded end  432  may be inserted in and turned by manipulating the engagement member  415  to engage a corresponding threading in the hole  108 A, thereby securing the cage structure  100  to the contact head  430 . The orientation guide  434  may be inserted in the hole  108 B, so as to properly align the implant tool  400  with respect to the cage structure  100 , while preventing the cage structure  100  from rotating with respect to the contact head  430 . 
     The hole  108 A may be located, for example, at the center of the wall surface  104 B. The hole  108 A may have a larger diameter than the hole  108 B. The hole  108 A may be threaded to engage the threaded end  432  of the implant tool  400 . The hole  108 B may be constructed to engage the orientation guide  434  of the implant tool  400 . The hole  108 A may be deeper than the hole  108 B. 
     Once the implant tool  400  is securely and fixedly attached to the cage structure  100 , the surgeon may align and implant the cage structure  100  in the space prepared for implanting of the cage structure  100 . If applicable, the surgeon may implant a plating device (not shown), which may be secured to the adjacent vertebrae  4 , as is known by those skilled in the art. After the cage structure  100  is properly positioned in the space between the vertebrae  4 , the surgeon may release the cage structure  100  by turning the engaging member  415  in the opposite direction to unthread the threaded end  432 . 
     The cage structure  100  may include a wall portion  106 A that may be bulged inwardly to provide added strength for the area surrounding the hole  108 A, so as to be able receive and withstand substantial force that may be applied to the cage structure  100  through the implant tool  400 . 
     Referring to  FIG. 4A , the cage structure  100  may be constructed with two or more parts, including the main body  110  and one or more plates  150 A,  150 B. The cage structure  100  may further include one or more fasteners (e.g., pins  190 A,  190 B,  190 C) to secure the one or more plates  150 A,  150 B to the main body  110 . 
     The main body  110  and the first and second plates  150 A,  150 B may be formed of one or more robust, strong and ductile materials, such as, for example, a polymer, a metal, an alloy, or the like. For example, the main body  110  may be formed of PEEK, and the first and second plates  150 A,  150 B may be formed of titanium or a titanium alloy. The main body  110  and the first and second plates  150 A,  150 B may be a single unitary piece or an assembly of two or more parts that are independently produced. 
     As seen in  FIG. 4A , the main body  110  may have a first surface  112  (shown facing upwardly) and a second surface (not shown) located opposite to the first surface  112  and facing in the opposite direction. Side surfaces of the main body  110  may be exposed, and the wall surfaces  104 A,  104 B,  104 C of the cage structure  100  may be the side wall surfaces of the main body  110 . The anterior wall surface  104 B may be wider than the posterior wall surface  104 A, and the first main surface  102  and the second main surface (not shown) may have a generally trapezoidal shape with rounded corners. The anterior wall surface  104 B may be thicker (or wider) than the posterior wall surface  104 A, and the side or lateral wall surfaces  104 C may have a generally trapezoidal shape. 
     The first and second plates  150 A,  150 B may be attached to the first surface  112  and the second surface (not shown) of the main body  110 , respectively. The main body  110  may be vertically and/or horizontally symmetric, in which case the first surface  112  may be configured to contact either or both of the surfaces of the first and second plates  150 A,  150 B. The first and second plates  150 A,  150 B may have substantially the same shape and construction, and hence may be interchangeably used. Alternatively, the first surface  112  and the second surface (not shown) of the main body  110  may have different shapes and constructions; and, the first and second plates  150 A,  150 B may be shaped and constructed differently to fit to the first surface  112  and the second surface, respectively. 
     The main body  110  may have an opening  105 A (shown in  FIG. 4A ) extending from the first surface  112  to the second surface (not shown) of the main body  110 . The opening  105 A may be located, for example, at or near the center of the main body  110 . The opening  105 A may be defined by an inner wall surface  116  of the main body  110 . The holes  108 A,  108 B may be formed in the main body  110 , and the inner surface  116  may have a bulged portion  116 A to provide added strength and stability around the hole  108 A. The first and second plates  150 A,  150 B may have openings  105 B,  105 C, respectively, which may be formed corresponding to the opening  105 A. A retention member (not shown), such as, for example, a mesh, a grid, or the like, may be formed in the openings  105 B and/or  105 C, so as to retain a bone graft material in the opening  105 A. The retention member should have a structure, so as to promote fusion and bone growth between the bone graft material and the adjacent vertebra. The openings  105 A.  105 B,  105 C may collectively form the opening  105  (shown in  FIGS. 3A and 3B ). 
     As seen in  FIG. 4A , the first and second plates  150 A and  150 B may have an outer surface  152  (shown with the first plate  150 A) and an inner surface  154  (shown with the second plate  150 B). The inner surface  154  may be substantially flat and smooth. The first surface  112  and the second surface (not shown) of the main body  110  may be substantially flat and smooth. The inner surfaces  154  may be in direct contact with the first surface  112  and the second surface (not shown) of the man body  110 . 
     The first and second plates  150 A,  150 B may be attached to the main body  110  by an adhesive, a fastener, or the like. For example, the first plate  150 A may be adhered to or snapped in the main body  110 . Alternatively or additionally, the first and second plates  150 A,  150 B may be attached to the main body  110  by one or more fasteners, such as, for example, a pin, a screw, a rivet, a bolt, a nut, or the like. For example, the main body  110  may include one or more pin holes  117  (three shown in  FIG. 4A ). The first plate  150 A may have one or more pin holes  157  (three shown in  FIG. 4A ), which may be aligned with the pin holes  117  of the main body  110 . One or more pins  190  (three shown in  FIG. 4A ) may be driven into the pin holes  157  and the pin holes  117  to attach the first plate  150 A on the first surface  112  and/or the second plate  150 B of the main body  110 . The pins  190  may be radiopaque or radiolucent. 
     Alternative or additionally, the main body  110  and the first and second plates  150 A,  150 B may be constructed to structurally engage each other. For example, the first surface  112  of the main body  110  may have a wall  120  protruding upwardly and extending along a periphery of the first surface  112 . As seen in  FIGS. 3A and 3B , the wall  120  may surround the first plate  150 A such that the first plate  150 A may not move around laterally. 
     Additionally, the main body  110  may have one or more recesses  122 , and the first and second plates  150 A,  50 B may have one or more tabs  158 , which may be located and shaped to fit into the recesses  122  of the main body  110 . For example, as seen in  FIG. 4A , a pair of tabs  158  may be formed at a posterior edge of the first plate  150 A, and another pair of tabs  158  may be formed at right and left sides of the first plate  150 A, respectively. The main body  110  may have four recesses  122  (only one shown in  FIG. 4A ). A pair of recesses  122  may be formed at the wall  120  on a posterior portion of the main body  110 . Another pair of recesses  122  may be formed at the wall  120  on right and left portions of the main body  110 , respectively. Thus, the first and/or second plates  150 A,  150 B may be snapped into and held securely in position with respect to the main body  110 . 
     The first plate  150 A may have one or more cutouts  156  (two shown) and one or more push tabs  160  (more clearly shown with the second plate  150 B in  FIG. 4A ). The cutouts  156  may be positioned to render the first plate  150 A compressible. The push tabs  160  may be formed at a posterior portion of the first plate  150 A. The push tabs  160  may be pushed (or squeezed) toward each other to compress the first plate  150 A, which may result in inwardly retracting the tabs  158  on the right and left sides of the first plate  150 . Once the compressed first plate  150 A is placed on the first surface  112 , the push tabs  160  may be let go to decompress the first plate  150 A, and the tabs  158  may be inserted and fit into the corresponding recesses  122 , respectively. Once the tabs  158  are inserted into the recesses  122 , the first plate  150 A may not move vertically or horizontally. As seen in  FIG. 4A , the wall  120  may be discontinued at a posterior portion of the main body  110  where the push tabs  158  are placed. The second plate  150 B may be constructed in a similar manner and attached to the main body  110  in a similar manner. 
     The outer surface  152  of the first and second plates  150 A,  150 B may have a surface pattern  170  that may form the first main surface  102  and/or the second main surface (not shown). The surface pattern  170  may establish and promote bone growth and resist movement (e.g., departure, slippage, etc.) installed with respect to a vertebra. The surface pattern  170  may include a symmetrical geometric pattern (e.g., circle, sphere, semi-sphere, equilateral triangle, pyramid, isosceles triangle, square, rectangle, kite, rhombus, pentagon, hexagon, heptagon, octagon, or the like), an asymmetrical geometric pattern (e.g., irregular sphere or semi-sphere, scalene triangle, irregular pyramid, irregular quadrilateral, irregular pentagon, irregular hexagon, irregular heptagon, irregular octagon, or the like), a combination of one or more symmetrical geometric patterns and/or one or more asymmetrical geometric patterns, and/or the like. The surface pattern  170  may be formed by, for example, machining, chemically machining, and/or stamping the outer surface  152 . Alternatively or additionally, the outer surface  152  may be chemically processed by performing micro-surface treatments, such as, for example, chemical etching, hydroxylapatite coating, and/or the like. The surface pattern  170  may have a structure shown in  FIG. 7A or 7B  and described below. 
       FIGS. 5A-5F and 6  illustrate various views of another cage structure  200  that is constructed according to the principles of the disclosure.  FIG. 5A  illustrates a perspective view of the cage structure  200 ;  FIG. 5B  illustrates another perspective view of the cage structure  200 ;  FIGS. 5C, 5D, 5E, 5F  illustrate superior (or inferior), anterior, lateral and posterior views of the cage structure  200 , respectively; and  FIG. 6  illustrates an exploded perspective view of the cage structure  200 . 
       FIG. 5G  illustrates yet another example of a cage structure  200 ′ that is constructed according to the principles of the disclosure. 
       FIG. 7A  illustrates a side cut view of a surface pattern of the cage structure  200  (or the cage structure  100  shown in  FIGS. 3A-4A , or the cage structure  200 ′ shown in  FIG. 5G ).  FIG. 7B  illustrates a side cut view of another example of a surface pattern of the cage structure  200  (or the cage structure  100  shown in  FIGS. 3A-4A , or the cage structure  200 ′ shown in  FIG. 5G ). 
     Referring  FIGS. 5A-5F, and 6-7A  concurrently, the cage structure  200  may have a first surface  202  (shown facing upwardly) and a second surface  204  (shown facing downwardly) located opposite to the first surface  202 , and a plurality of side surfaces (e.g., a posterior surface  206 A, an anterior surface  206 B, and lateral surfaces  206 C and  206 D). The anterior surface  206 B may be wider and thicker than the posterior surface  206 A. Hence, as seen in  FIG. 5C , the first surface  202  (and the second surface  204 ) may have a generally trapezoidal shape with rounded corners in the lateral (or horizontal) plane. Also, as seen in  FIG. 5E , the lateral surfaces  206 C and  206 D may be tapered from the anterior surface  206 B to the posterior surface  206 A. The cage structure  200  may be vertically symmetric, and may be turned over vertically when inserted into a body of a patient. The cage structure  200  may be horizontally symmetric. 
     As seen in  FIGS. 5A, 5B, 5D and 6 , the cage structure  200  may include one or more holes (or openings), such as, for example, a hole  218 A and a hole  218 B. Alternatively (or additionally), the cage structure  100  may include fastening holes (not shown) that may be configured to receive one or more bone fasteners (e.g., bone screws  12  shown in  FIG. 2 ) to secure the cage structure  200  to adjacent vertebra. In this regard, the fastening holes (not shown) may be angled so as to guide the bone fasteners toward and into the adjacent vertebrae.  FIG. 2  shows an example of fastening holes formed in an implantable device and angled so as to guide the bone screws  12  toward and into adjacent vertebrae  4 . 
     Referring to  FIGS. 5A, 5B, 5D, and 6 , the holes  218 A,  218 B may extend inwardly from the anterior surface  206 B to engage, for example, the implant tool  400  (shown in  FIG. 4B ) or the like. For example, similar to the holes  108 A,  108 B of the cage structure  100 , the holes  218 A,  218 B may be constructed to engage the threaded end  432  of the inner shaft and an orientation guide, respectively, of the implant tool  400 , shown in  FIG. 4B . The cage structure  200  may be implanted in a patient in substantially the same manner as the cage structure  100 , described above. 
     The cage structure  200  may include an opening  240 , which may extend from the first surface  202  to the second surface  204 . The opening  240  may be a graft chamber, or the like, similar to the opening  105  (shown in  FIGS. 3A and 3B ) discussed above. As seen in  FIG. 5C , the opening  240  may be formed at, for example, a center portion of the cage structure  200 . The opening  240  may be laterally surrounded and defined by an inner wall surface  216 . The inner wall surfaces  216  may have a wall portion  216 A that may bulge inwardly to provide added strength for the area surrounding the hole  218 A, so as to be able receive and withstand substantial force that may be applied to the cage structure  200  through the implant tool  400 . 
     The first and second surfaces  202 ,  204  may have a surface pattern  270 , which may be configured to directly contact a surface of the adjacent vertebra during implantation. The surface pattern  270  may establish and promote bone growth and resist movement (e.g., departure, slippage, or the like). 
     As seen in  FIGS. 7A and 7B , the surface pattern  270  may include a plurality of protrusions  272  with a plurality of gaps  274  therebetween. A bottom portion of the protrusions  272  may be caved in with each lateral inner wall of adjacent protrusions  272  formed at an angle θ (shown in  FIG. 7B ) with respect to the normal axis of the surface pattern  270 , thereby forming an undercut  276  that enlarges a bottom portion of the gaps  274 . The angle θ may range anywhere from 0° and 45°. However, the angle θ may be less than 0° or greater than 45° with respect to the normal axis. The gap  274  enlarged by the undercut  276  may function as a bone lock post, which may promote bone fusion and growth. 
     The protrusions  272  may include a pocket  278 , which may be a hole or a slot formed at a superior (or inferior) surface  279  thereof, to increase a bone growth area. The superior surfaces  279  may have one or more symmetric geometry shapes, one or more asymmetric geometry shapes, a combination of a symmetric geometry shape and an asymmetric geometry shape, or the like. Two neighboring protrusions  272  may have different superior surface shapes.  FIG. 7B  shows an example wherein one of the two neighboring protrusions  272  may have a triangular or pyramid-shaped superior surface  2791  and the other may have a circular or semi-spherical-shaped superior surface  2791 . The protrusions  272  with different surface shapes may be arranged alternatingly. 
       FIG. 5G  shows another example of a cage structure  200 ′ that is constructed according to the principles of the disclosure. The cage structure  200 ′ may be made entirely of a metal (e.g., titanium) or metal alloy (e.g., titanium alloy). The cage structure  200 ′ may be formed as a single piece, having first and second surfaces  202 ,  204 , with either or both surfaces having the surface pattern  270 . As seen, the cage structure  200 ′ may include one or more openings or windows  299 . Such windows  299  may remain empty and/or may be filled with radiolucent material such as tissue grafts as will be described in further detail below. Window(s)  299  may enable a medical professional to view and/or determine the level of post-operative fusion between cage structure  200 ′ (or  200 ) and patient bone and/or tissue. The cage structure  200 ′ body may define any appropriate arrangement, number, and configuration of windows  299 . That is, as shown in  FIG. 5G , for example, the cage structure  200 ′ may include a pair of windows  299  on each lateral side. Each window  299  may be generally quadrilateral (e.g., square, rectangular, or trapezoidal). In some arrangements, a radiolucent structure, such as a graft containment sheath, may be disposed along one or more portions of cage structure  200 ′. Indeed, such graft containment sheaths may substantially fill or encompass window  299 . Accordingly, when the cage structure  200 ′ is placed between two adjacent vertebrae  4  (shown in  FIG. 1 ) under X-ray vision, window  299  remains radiolucent such that fusion within and/or through window  299  may be observed. 
     As seen in  FIG. 6 , the cage structure  200  may be constructed as one, two, or more parts. The cage structure  200  may be constructed as a shell  210  and/or an insertion (or main body)  250 . The cage structure  200  may further include one or more fasteners (e.g., pins  290 ). The shell  210  may have an opening  240 A formed at a center portion. The shell  210  may be constructed as a single piece that includes only the shell  210  or insertion  250 , or with two or more pieces that are assembled together, including the shell  210  and insertion  250 . The insertion  250  may include one or more windows, such as, for example, window  299  shown in  FIG. 5G  and described above. 
     For example, as seen in  FIG. 5E , the shell  210  may be constructed with a shell main body  212  and one or more surface layers  214 A,  214 B. The shell main body  212  may have a generally clam shape (or U-shape). The shell main body  212  may include a bridge portion  212 A and a pair of wing portions  212 B,  212 C extending from two opposite sides of the bridge portion  212 A. As seen in  FIG. 5F , the bridge portion  212 A may form the anterior surface  206 A. The bridge portion  212 A may include an opening  228 . The opening  228  may function to allow blood, tissue, bone graft, etc., to flow into (or out from) the shell  210 . 
     The surface layers  214 A,  214 B may be attached to outer surfaces of the wing portions  212 B,  212 C, respectively, or the surface layers  214 A,  214 B may be integrally formed with the wing portions  212 B,  212 C. The surface layers  214 A,  214 B may include the first and second surfaces  202 ,  204 , respectively. Inner surfaces of the bridge portion  212 A and the wing portions  212 B,  212 C may be smooth and clean to reduce friction when the insertion  250  is inserted to a space surrounded by the shell  210 . 
     The shell main body  212  may be formed of one or more materials that may provide a visible fusion window. For example, the shell main body  212  may be formed of PEEK or the like. The surface layers  214 A,  214 B may be formed of one or more materials that can be processed to form the surface pattern  270  having, for example, undercut  276 , pocket  278 , and/or the like. For example, the surface layers  214 A,  214 B may be formed of titanium, a titanium alloy, or the like. 
     The shell  210  of the cage structure  200  may be used alone as a cage, without any other parts. For example, as seen in  FIGS. 9A and 9B , the shell  210  may be inserted between adjacent vertebrae  4  without the insertion  250 . Similarly, the insertion  250  may be used alone as a cage, without any other parts (not shown). 
     The insertion  250  may be constructed to fit into a space surrounded by the shell  210 . As seen in  FIG. 6 , the insertion  250  may have a plurality of surfaces, and some of the surfaces may form the posterior surface  206 B, and the lateral surfaces  206 C and  206 D of the cage structure  200 . Other surfaces, such as, for example, first insertion surface  252 , second insertion surface (not shown) located opposite to the first insertion surface  252 , anterior insertion surface (not shown) opposite to the posterior surface  206 B, and the like, may be covered and/or encapsulated by the shell  210  and may not be visible. The anterior insertion surface (not shown) may be partially exposed by the opening  228  located at the anterior surface  206 A of the cage structure  200 . An opening  240 B may be formed at a center portion of the insertion  250 . The openings  240 A and  240 B may collectively form the opening  240  of the cage structure  200 . 
     The insertion  250  may be formed of metal (e.g., titanium, a titanium alloy, or the like), a radiopaque or radiolucent material (e.g., PEEK), an elastic and/or shock-absorbing material (e.g., silicon), an allograft bone, or the like. The insertion  250  may be a single unitary piece or a combination of multiple pieces that are manufactured separately. As noted earlier, the insertion  250  may include one or more windows, such as, for example, window  299  shown in  FIG. 5G  and described above. 
     The shell  210  and the insertion  250  may be assembled together by an adhesive, a fastener, or the like. For example, the shell  210  and the insertion  250  may be glued together. Alternatively or additionally, the shell  210  may be attached to the insertion  250  by one or more fasteners, such as, for example, a pin, a screw, a rivet, a bolt, a nut, or the like. 
     For example, as seen in  FIGS. 5C and 6 , the shell  210  may have one or more pin holes  234  (e.g., two) formed at an anterior (or posterior) portion of the first surface  202 . The insertion  250  may also one or more pin holes  254  formed at an anterior (or posterior) portion of the first insertion surface  252 . The pin holes  234  and  254  may be aligned when the shell  210  and the insertion  250  are put together. One or more corresponding pins  290  may be inserted into the pin holes  234  and  254  to affix the shell  210  to the insertion  250 . The pins  290  maybe radiopaque or radiolucent. 
     The shell  210  and the insertion  250  may be constructed to mate to each other and form a unitary structure. For example, one or more slots  256  (e.g., two shown in  FIG. 6 ) may be formed on at least one of the first insertion surface  252  and the second insertion surface (not shown). The slots  256  may be formed at a anterior portion of the insertion  250  and may extend laterally along the anterior surface  206 B. The slots  256  may be tapered from a bottom (or inferior) end to an open upper (or superior) end thereof. The shell  210  may have one or more guides  236  (e.g., two shown in  FIG. 6 ) formed corresponding to the one or more slots  256 , respectively. The guides  236  may be tapered to fit the tapered slots  256  of the insertion  250 . The shell  210  and the insertion  250  may be conjoined by aligning an end of the guide  236  with an end of the slot  256  and then pushing the insertion  250  in a direction shown as arrow A into the space surround by the shell  210  (or pushing the shell  210  toward the insertion  250  in the direction opposite to arrow A). The tapered guides  236  and the slots  256  may form a dovetail-like joint that holds the shell  210  and the insertion  250  together. 
     The cage structure(s) described herein, including cage structure  200  (or  100 ) may include additional features, constructed according to the principles of the disclosure. For instance, the cage structures described herein may include one or more anchoring ears that may be integrally formed with the cage structures. 
       FIGS. 8A and 8B  illustrate a further embodiment of the cage structure  200  (or  100 ). The cage structure  200  (or  100 ) may include one or more anchoring ears that may be integrally formed with the shell  200  (shown in  FIG. 5B ), or the main body  110  (shown in  FIG. 4B ), or one or more of the plates  150 A,  150 B (shown in  FIG. 4B ). 
     Referring to  FIGS. 8A and 8B , the cage structure  200  (or  100 ) may include one or more bone anchoring ears  260 A,  260 B. As seen in  FIGS. 8A, 8B , the cage structure may include the shell  210 ′, which includes the bone anchoring ears  260 A,  260 B. The bone anchoring ears  260 A,  260 B may include one or more screw holes  262 . The bone anchoring ears  260 A,  260 B may be integrally formed with the main body  212  of the shell  210 ′. For example, the wing portions  212 B,  212 C of the main body  212  may have portions extending beyond the surface layers  214 A,  214 B, respectively. The extended portions of the wing portions  212 B,  212 C may be drilled to form the screw holes  262  and may then be bent away from each other to form the ears  260 A,  260 B, respectively. Alternatively, the ears  260 A,  260 B may be produced independently and then attached to edges of the wings  212 B,  212 C of the main body  210 , respectively. Alternatively, the ears  260 A,  260 B may be formed with the wing portions  212 B,  212 C, including holes therein, and bent, as understood by those skilled in the art. 
     The cage structure  200  may be modified to include screw holes without adding the bone anchoring ears  260 A,  260 B shown in  FIGS. 8A and 8B . 
       FIGS. 8C and 8D  illustrate a further example of a cage structure  200  that is constructed according to the principles of the disclosure. 
     Referring to  FIGS. 8C and 8D , the cage structure  200  may include a shell  210 ′ having an anterior coronal face  260  and one or more screw holes (e.g., four)  262 . The face  260  may be integrally formed with the main body  212  of the shell  210 ′. As seen in  FIG. 8D , the wing portions  212 B,  212 C of the main body  212  may have the surface layers  214 A,  214 B, respectively, which may be integrally formed with the main body  212  or attached as plates (such as, e.g., plates  150 A,  150 B, shown in  FIGS. 3A-4A . The wing portions  212 B,  212 C may include the tapered guides  236  to receive and guide an insertion  250 . 
     The cage shell  210 ′ may be implanted in a patient using a process similar to that described for the interbody device  410  or interbody system  400  described in U.S. patent application Ser. No. ______ (Attorney Docket No. 2071269-5013US), filed ______, titled “Modular Plate and Cage Elements and Related Methods,” the entirety of which is incorporated herein by reference, with references to FIGS. 18A-18C of that application. 
       FIGS. 10A and 10B  illustrate a cage structure  200  having a modified insertion  250 , which is constructed according to the principles of the disclosure. The modified insertion  250  may include one or more screw holes  264 A,  264 B, which may extend from the anterior surface  206 B to the inner surface  216 . As seen in  FIG. 10B , one or more screws  266 A,  266 B may be inserted into the corresponding screw holes  266 A,  266 B. The screw hole  264 A may be slanted to direct the screw  266 A upwardly, and the screw hole  264 B may be slanted to direct the screw  266 B downwardly. 
       FIG. 10C  illustrates another example of a cage structure  200 ′ that is constructed according to the principles of the disclosure. As seen, the cage structure  200 ′ may comprise the shell  210  and/or the insertion  250 , wherein the insertion  250  may include superior and/or inferior slots  256  that align with and engage corresponding one or more guides  236  on the shell  210 . The insertion  250  may have an open arrangement (shown in  FIG. 10C ) or a closed arrangement (shown in  FIG. 10D ). 
       FIG. 10D  illustrates an example of an insertion  250  have a closed arrangement. As seen in  FIG. 10D , at least one of the walls may be formed by a thin wall membrane  162 , which is illustrated and described in U.S. patent application Ser. No. ______ (Attorney Docket No. 2071269-5013US), filed ______, titled “Modular Plate and Cage Elements and Related Methods,” the entirety of which has been incorporated herein by reference. 
       FIGS. 10E and 10F  illustrate perspective anterior and lateral views, respectively, of another example of a cage structure constructed according to the principles of the disclosure. The cage structure seen in  FIGS. 10E and 10F  may be used in corpectomy applications. The cage structure includes the shell  210  and insertion  250 , which when assembled may have a height that may range from, for example, about 4 mm to about 200 mm. Other heights are contemplated herein, including less than 4 mm or greater than 200 mm. 
     As seen in  FIGS. 10E and 10F , the cage structure may include one or more holes (or openings), such as, for example, hole  218 A and hole or recessed portion  218 B. Alternatively (or additionally), the cage structure may include fastening holes (not shown) that may be configured to receive one or more bone fasteners (e.g., bone screws  12  shown in  FIG. 2 ) to secure the cage structure to vertebrae. In this regard, the fastening holes (not shown) may be angled so as to guide the bone fasteners toward and into the vertebrae.  FIG. 2  shows an example of fastening holes formed in an implantable device and angled so as to guide the bone screws  12  toward and into adjacent vertebrae  4 . 
     The holes  218 A,  218 B may extend inwardly from the anterior surface  206 B to engage, for example, the implant tool  400  (shown in  FIG. 4B ) or the like. For example, similar to the holes  108 A,  108 B of the cage structure  100 , the holes  218 A,  218 B may be constructed to engage the threaded end  432  of the inner shaft and an orientation guide, respectively, of the implant tool  400 , shown in  FIG. 4B . 
     The cage structure may include one or more openings  240 , which may extend from the first surface  202  to the second surface  204 . The opening  240  may be a graft chamber, as discussed above. As seen in  FIGS. 10E and 10F , the opening  240  may be formed at, for example, a center portion of the cage structure. The opening  240  may be laterally surrounded and defined by inner wall surfaces of the insertion  250  and shell  210 . The shell  210  may include an opening  228 . The shell  210  may be secured to the insertion  250  via one or more fasteners (e.g., two)  190 . For instance, once the insertion  250  is inserted between the wing portions  212 B,  212 C along guides  236  and located in its final assembly position upper (shown in  FIGS. 10E, 10F ), the fasteners  190  may be inserted at a surface of the wing portion  212 B (or  212 C) and longitudinally through the insertion  250  to and through the other wing portion  212 C (or  212 B), whereby the fastener  190  will secure the shell  210  to the insertion  250 . 
     The first and second surfaces  202 ,  204  may have a surface pattern  270 , which may be configured to directly contact a surface of the adjacent vertebra during implantation. The surface pattern  270  may establish and promote bone growth and resist movement (e.g., departure, slippage, or the like), as described above. 
       FIGS. 11A and 11B  illustrate another example of a cage structure  300 , which is constructed according to the principles of the disclosure. The cage structure  300  may be constructed with an insertion portion  310  and a mounting plate  320 . The insertion portion  310  may be any cage that is inserted between adjacent vertebrae  4 A,  4 B. For example, the insertion portion  310  may be the cage structure  200  shown in  FIG. 5A  or the cage structure  100  shown in  FIGS. 3A-4A . The mounting plate  320  may have a first main surface  322  and a second main surface (not shown) located opposite to the first main surface  322 . The insertion portion  310  may be connected to a center portion of the second main surface (not shown), which divides the mounting plate  320  into an upper portion  320 A and a lower portion  320 B. 
     The mounting plate  320  may include a plurality of screw holes which extend from the first main surface  322  to the second main surface (not shown). For example, one or more screw holes  324 A (two shown) may be formed at the upper portion  320 A, and one or more screw holes  324 B (two shown) may be formed at the lower portion  320 B. The screw holes  324 A formed at the upper portion  320 A may be slanted upwardly to direct bone screws (not shown) inserted thereto further up from a bottom of the vertebrae  4 A. The screw holes  324 B formed at the lower portion  320 B may be slanted downwardly to direct bone screws (not shown) inserted thereto further down from a top of the vertebrae  4 B. The insertion portion  310  and the mounting plate  320  may be integrally formed, or, alternatively, produced independently from each other and assembled together. 
     While the disclosure has been described in terms of exemplary embodiments, those skilled in the art will recognize that the disclosure can be practiced with modifications in the spirit and scope of the appended claim, drawings and attachment. The examples provided herein are merely illustrative and are not meant to be an exhaustive list of all possible designs, embodiments, applications or modifications of the disclosure.