Patent Publication Number: US-2022218494-A1

Title: Expandable spinal implant system and method

Description:
The present application is a continuation of U.S. application Ser. No. 16/829,421, filed Mar. 25, 2020; which is a continuation of U.S. application Ser. No. 14/885,472, filed Oct. 16, 2015, which are hereby incorporated by reference herein in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure generally relates to medical devices for the treatment of musculoskeletal disorders, and more particularly to a surgical system that includes an expandable spinal implant, systems for implanting an expandable spinal implant, and a method for treating a spine. 
     BACKGROUND 
     Spinal disorders such as degenerative disc disease, disc herniation, osteoporosis, spondylolisthesis, stenosis, scoliosis and other curvature abnormalities, kyphosis, tumor, and fracture may result from factors including trauma, disease and degenerative conditions caused by injury and aging. Spinal disorders typically result in symptoms including pain, nerve damage, and partial or complete loss of mobility. 
     Non-surgical treatments, such as medication, rehabilitation and exercise can be effective, however, may fail to relieve the symptoms associated with these disorders. Surgical treatment of these spinal disorders includes fusion, fixation, correction, discectomy, laminectomy and implantable prosthetics. As part of these surgical treatments, spinal constructs, such as, for example, bone fasteners, spinal rods and interbody devices can be used to provide stability to a treated region. For example, during surgical treatment, interbody devices may be introduced to a space between adjacent vertebral bodies (the interbody space) to properly space the vertebral bodies and provide a receptacle for bone growth promoting materials. 
     More recently, interbody devices have been introduced that provide additional capability beyond static spacing of the vertebral bodies. For example, some devices have expansion capability such that the implant may be introduced to the interbody space in a collapsed state and then expanded to produce additional spacing and, in some cases, introduce or restore curvature to the spine by expanding selectively on only one end or portion of the implant. However, many existing expandable interbody designs utilize internal mechanisms that may inhibit the introduction of bone growth promoting material into the interbody implant by a surgeon after the implant is expanded. The present disclosure seeks to address this and other shortcomings in the existing art. 
     SUMMARY 
     In one embodiment, an expandable spinal implant is provided. The implant includes a frame comprising a proximal wall and a distal wall, wherein the proximal wall defines a proximal aperture and the distal wall defines a distal aperture. The implant also includes a plug movably disposed in the distal aperture of the frame and an endplate operably engaged with the frame and configured to expand outward from the frame when the plug is moved in a distal direction relative to the frame. 
     In one alternative embodiment a system is provided including an expandable spinal implant and an insertion instrument. The insertion instrument comprises a cannulated outer shaft and a driver shaft removably and rotatably disposed within the cannulated outer shaft. The expandable spinal implant comprises a frame with a proximal wall and a distal wall, wherein the proximal wall defines a proximal aperture and the distal wall defines a distal aperture. The proximal wall of the frame is configured to receive a distal end of the cannulated outer shaft for manipulating the expandable spinal implant. The expandable spinal implant also comprises a movable plug disposed in the distal aperture of the frame, wherein the plug comprises an interface configured to be operably engaged by a distal end of the driver shaft to move the plug relative to the frame. The expandable spinal implant also comprises an endplate engaged with the frame and configured to move relative to the frame when the plug is moved by the driver shaft of the insertion instrument. The driver shaft is also configured to be removable from the cannulated outer shaft of the insertion instrument such that after the plug has been moved distally relative to the frame, a bone growth promoting material may be introduced into the frame through the cannulated outer shaft of the insertion instrument. In some embodiments, various other implants, systems and methods are disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is further informed by the specific description accompanied by the following drawings, in which: 
         FIG. 1  is a perspective view of one embodiment of an expandable spinal implant system in a closed configuration in accordance with the principles of the present disclosure; 
         FIG. 2  is a perspective view one embodiment of an expandable spinal implant system in an open configuration in accordance with the principles of the present disclosure; 
         FIG. 3  is a perspective view of the components shown in  FIG. 1  but with one endplate removed to show inner structures of a closed expandable spinal implant system in accordance with the principles of the present disclosure; 
         FIG. 3A  is a perspective view of an endplate component in accordance with the principles of the present disclosure; 
         FIG. 4  is a perspective view of the components shown in  FIG. 1  but with one endplate removed to show inner structures of an open expandable spinal implant system in accordance with the principles of the present disclosure; 
         FIG. 5  is a perspective view of one embodiment of an expandable spinal implant system in a closed configuration in accordance with the principles of the present disclosure; 
         FIG. 6  is a perspective view one embodiment of an expandable spinal implant system in an open configuration in accordance with the principles of the present disclosure; 
         FIG. 7  is a perspective view of the components shown in  FIG. 5  but with one endplate removed to show inner structures of a closed expandable spinal implant system in accordance with the principles of the present disclosure; 
         FIG. 8  is a perspective view of the components shown in  FIG. 6  but with one endplate removed to show inner structures of an open expandable spinal implant system in accordance with the principles of the present disclosure; 
         FIG. 9  is a perspective view of the components of an expandable spinal implant system including an insertion instrument engaged with an expandable spinal implant in accordance with the principles of the present disclosure; 
         FIG. 10  is a perspective view of the components shown in  FIG. 9  also showing a driver shaft extended through the cannula and in engagement with the plug; 
         FIG. 11  is a perspective view of the components shown in  FIG. 9  also showing a driver shaft extended through the cannula and in engagement with the plug to expand the endplates relative to the frame; 
         FIG. 12  is a perspective view of the components shown in  FIG. 9  also showing the driver shaft removed from the cannula; 
         FIG. 13  is a top view of one embodiment of an expandable spinal implant system as used in a PLIF surgical procedure in accordance with the principles of the present disclosure; 
         FIG. 14  is a perspective view of the components shown in  FIG. 13  as used in a PLIF surgical procedure in accordance with the principles of the present disclosure; 
         FIG. 15  is a top view of one embodiment of an expandable spinal implant system as used in a TLIF surgical procedure in accordance with the principles of the present disclosure; 
         FIG. 16  is a perspective view of the components shown in  FIG. 15  as used in a TLIF surgical procedure in accordance with the principles of the present disclosure; 
         FIG. 17  is a perspective view of the components shown in  FIG. 15  as used in a TLIF surgical procedure in accordance with the principles of the present disclosure; and 
         FIG. 18  is a perspective view of one embodiment of an expandable spinal implant system with a single movable endplate and wherein the frame may be substantially integral with at least one endplate. 
     
    
    
     DETAILED DESCRIPTION 
     The exemplary embodiments of the surgical system and related methods of use disclosed are discussed in terms of medical devices for the treatment of musculoskeletal disorders and more particularly, in terms of an expandable surgical implant system that may include an expandable spinal implant, an insertion instrument and/or a method for treating a spine. 
     In some embodiments, the present system includes an expandable spinal implant system suitable for insertion from a direct posterior (sometimes referred to as PLIF procedures) in pairs or singularly and then expandable at a distal end in order to impart and/or augment a lordotic curve of the spine. In some embodiments shown herein, the expandable spinal implant system may also be configured for use in oblique, postero-lateral procedures and/or transforaminal lumbar interbody fusions (sometimes referred to as TLIF procedures). Additionally, the frame disclosed in various embodiments may be configured to place a movable plug of the spinal implant in a substantially distal position within the spinal implant so as to clear a proximal volume within the implant for packing with bone-growth promoting materials after the implant has been inserted and/or expanded using the various techniques described herein. The frame and other various spinal implant components may also be configured with one or more sidewalls and/or openings to direct bone-growth promoting material to a selected area of an intervertebral or interbody space after the insertion and/or deployment of the spinal implant. In some embodiments, the spinal implant system may also be provided with a tapered distal tip (as viewed from a superior or top surface) such that the implant is shaped for insertion from an oblique approach and placement at a diagonal across an intervertebral or interbody space. 
     In some embodiments, the spinal implant system may also be employed to restore and/or impart sagittal balance to a patient by increasing and/or restoring an appropriate lordotic angle between vertebral bodies at a selected level where the spinal implant is implanted and expanded. In some embodiments, a pair of such spinal implants may be employed from bilateral PLIF approaches and expanded to differing heights to impart and/or restore both a lordotic angle as well as align the spine in the coronal plane (so as to treat a scoliotic curvature, for example). In some embodiments, a single such spinal implant may be employed from a postero-lateral TLIF approach and expanded to differing heights to impart and/or restore both a lordotic angle as well as align the spine in the coronal plane (so as to treat a scoliotic curvature, for example). In the various embodiments described, the spinal implant system may be useful in a variety of complex spinal procedures for treating spinal conditions beyond one-level fusions. Furthermore, the spinal implant system described in the enclosed embodiments may also be used as a fusion device with an expandable height for tailoring the implant to a particular interbody disc space to restore the spacing between adjacent vertebral bodies and facilitate spinal fusion between the adjacent vertebral bodies. 
     In some embodiments, and as mentioned above, the present disclosure may be employed to treat spinal disorders such as, for example, degenerative disc disease, disc herniation, osteoporosis, spondylolisthesis, stenosis, scoliosis and other curvature abnormalities, kyphosis, tumor and fractures. In some embodiments, the present disclosure may be employed with other osteal and bone related applications, including those associated with diagnostics and therapeutics. In some embodiments, the disclosed spinal implant system may be alternatively employed in a surgical treatment with a patient in a prone or supine position, and/or employ various surgical approaches to the spine, including anterior, posterior, posterior mid-line, direct lateral, postero-lateral oblique, and/or antero lateral oblique approaches, and in other body regions. The present disclosure may also be alternatively employed with procedures for treating the lumbar, cervical, thoracic, sacral and pelvic regions of a spinal column. The spinal implant system of the present disclosure may also be used on animals, bone models and other non-living substrates, such as, for example, in training, testing and demonstration. 
     The present disclosure may be understood more readily by reference to the following detailed description of the embodiments taken in connection with the accompanying drawing figures, which form a part of this disclosure. It is to be understood that this application is not limited to the specific devices, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting. In some embodiments, as used in the specification and including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” or “approximately” one particular value and/or to “about” or “approximately” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It is also understood that all spatial references, such as, for example, horizontal, vertical, top, upper, lower, bottom, left and right, are for illustrative purposes only and can be varied within the scope of the disclosure. For example, the references “upper” and “lower” are relative and used only in the context to the other, and are not necessarily “superior” and “inferior”. 
     As used in the specification and including the appended claims, “treating” or “treatment” of a disease or condition refers to performing a procedure that may include administering one or more drugs, biologics, bone grafts (including allograft, autograft, xenograft, for example) or bone-growth promoting materials to a patient (human, normal or otherwise or other mammal), employing implantable devices, and/or employing instruments that treat the disease, such as, for example, micro-discectomy instruments used to remove portions bulging or herniated discs and/or bone spurs, in an effort to alleviate signs or symptoms of the disease or condition. Alleviation can occur prior to signs or symptoms of the disease or condition appearing, as well as after their appearance. Thus, treating or treatment includes preventing or prevention of disease or undesirable condition (e.g., preventing the disease from occurring in a patient, who may be predisposed to the disease but has not yet been diagnosed as having it). In addition, treating or treatment does not require complete alleviation of signs or symptoms, does not require a cure, and specifically includes procedures that have only a marginal effect on the patient. Treatment can include inhibiting the disease, e.g., arresting its development, or relieving the disease, e.g., causing regression of the disease. For example, treatment can include reducing acute or chronic inflammation; alleviating pain and mitigating and inducing re-growth of new ligament, bone and other tissues; as an adjunct in surgery; and/or any repair procedure. Also, as used in the specification and including the appended claims, the term “tissue” includes soft tissue, ligaments, tendons, cartilage and/or bone unless specifically referred to otherwise. The term “bone growth promoting material” as used herein may include, but is not limited to: bone graft (autograft, allograft, xenograft) in a variety of forms and compositions (including but not limited to morselized bone graft); osteoinductive material such as bone morphogenetic proteins (BMP) (including but not limited to INFUSE® available from Medtronic plc) and alternative small molecule osteoinductive substances; osteoconductive materials such as demineralized bone matrix (DBM) in a variety of forms and compositions (putty, chips, bagged (including but not limited to the GRAFTON® family of products available from Medtronic plc)); collagen sponge; bone putty; ceramic-based void fillers; ceramic powders; and/or other substances suitable for inducing, conducting or facilitating bone growth and/or bony fusion of existing bony structures. Such bone growth promoting materials (denoted “BG” in some Figures herein) may be provided in a variety of solids, putties, liquids, colloids, solutions, or other preparations suitable for being packed or placed into or around the various implant  10 ,  20  embodiments described herein. 
     The following discussion includes a description of a surgical system including one or more spinal implants, related components and methods of employing the surgical system in accordance with the principles of the present disclosure. Various alternate embodiments are disclosed and individual components of each embodiment may be used with other embodiments. Reference is made in detail to the exemplary embodiments of the present disclosure, which are illustrated in the accompanying figures. Turning to  FIGS. 1-12 , there are illustrated components of a surgical system, such as, for example, an expandable spinal implant  10 ,  20  and associated system including an insertion instrument  30 . 
     The components of expandable spinal implant system  10 ,  20 ,  30  can be fabricated from biologically acceptable materials suitable for medical applications, including metals, synthetic polymers, ceramics and bone material and/or their composites. For example, the components of expandable spinal implant system (including, but not limited to implant  10 , implant  20 , insertion instrument  30 ), individually or collectively, can be fabricated from materials such as stainless steel alloys, commercially pure titanium, titanium alloys, Grade 5 titanium, super-elastic titanium alloys, cobalt-chrome alloys, stainless steel alloys, superelastic metallic alloys (e.g., Nitinol, super elasto-plastic metals, such as GUM METAL®), ceramics and composites thereof such as calcium phosphate (e.g., SKELITE™), thermoplastics such as polyaryletherketone (PAEK) including polyetheretherketone (PEEK), polyetherketoneketone (PEKK) and polyetherketone (PEK), carbon-PEEK composites, PEEK-BaSO 4  polymeric rubbers, polyethylene terephthalate (PET), fabric, silicone, polyurethane, silicone-polyurethane copolymers, polymeric rubbers, polyolefin rubbers, hydrogels, semi-rigid and rigid materials, elastomers, rubbers, thermoplastic elastomers, thermoset elastomers, elastomeric composites, rigid polymers including polyphenylene, polyamide, polyimide, polyetherimide, polyethylene, epoxy, bone material including autograft, allograft, xenograft or transgenic cortical and/or corticocancellous bone, and tissue growth or differentiation factors, partially resorbable materials, such as, for example, composites of metals and calcium-based ceramics, composites of PEEK and calcium based ceramics, composites of PEEK with resorbable polymers, totally resorbable materials, such as, for example, calcium based ceramics such as calcium phosphate, tri-calcium phosphate (TCP), hydroxyapatite (HA)-TCP, calcium sulfate, or other resorbable polymers such as polyaetide, polyglycolide, polytyrosine carbonate, polycaroplaetohe and their combinations. 
     Various components of spinal implant system  10  may be formed or constructed material composites, including the above materials, to achieve various desired characteristics such as strength, rigidity, elasticity, compliance, biomechanical performance, durability and radiolucency or imaging preference. The components of expandable spinal implant system  10 ,  20 ,  30 , individually or collectively, may also be fabricated from a heterogeneous material such as a combination of two or more of the above-described materials. The components of expandable spinal implant system  10 ,  20 ,  30  may be monolithically formed, integrally connected or include fastening elements and/or instruments, as described herein. For example, in some embodiments expandable spinal implant system  10 ,  20 ,  30  may comprise expandable spinal implants  10 ,  20  comprising PEEK and/or titanium structures with radiolucent markers (such as tantalum pins and/or spikes) selectively placed in the implant to provide a surgeon with placement and/or sizing information when the expandable spinal implant  10 ,  20  is placed in the spine. The components of expandable spinal implant system  10 ,  20 ,  30  may be formed using a variety of subtractive and additive manufacturing techniques, including, but not limited to machining, milling, extruding, molding, 3D-printing, sintering, coating, vapor deposition, and laser/beam melting. Furthermore, various components of the expandable spinal implant system  10 ,  20 ,  30  may be coated or treated with a variety of additives or coatings to improve biocompatibility, bone growth promotion or other features. For example, the endplates  140 ,  150 ,  240 ,  250  may be selectively coated with bone growth promoting or bone ongrowth promoting surface treatments that may include, but are not limited to: titanium coatings (solid, porous or textured), hydroxyapatite coatings, or titanium plates (solid, porous or textured). 
     Expandable spinal implant system  10 ,  20 ,  30  may be employed, for example, with a minimally invasive procedure, including percutaneous techniques, mini-open and open surgical techniques to deliver and introduce instrumentation and/or one or more spinal implants at a surgical site within a body of a patient, for example, a section of a spine. In some embodiments, expandable spinal implant system  10 ,  20 ,  30  may be employed with surgical procedures, as described herein, and/or, for example, corpectomy, discectomy, fusion and/or fixation treatments that employ spinal implants to restore the mechanical support function of vertebrae. In some embodiments, expandable spinal implant system  10 ,  20 ,  30  may be employed with surgical approaches, including but not limited to: posterior lumbar interbody fusion (PLIF), oblique lumbar interbody fusion, transforaminal lumbar interbody fusion (TLIF), various types of anterior fusion procedures, and any fusion procedure in any portion of the spinal column (sacral, lumbar, thoracic, and cervical, for example). Exemplary use of the expandable spinal implant system  10 ,  20 ,  30  in PLIF and TLIF techniques is shown generally in  FIGS. 13-17 . 
     As shown generally in  FIGS. 1-8 , two exemplary embodiments of an expandable spinal implant  10 ,  20  are shown (implant  10  is highlighted in exemplary  FIGS. 1-4  and implant  20  is highlighted in exemplary  FIGS. 5-8 ). Referring to  FIGS. 1-2 , expandable spinal implant  10  may comprise a frame  100  comprising a proximal wall  110  and a distal wall  120 . The frame  100  may provide a mechanism for placing an expansion mechanism distally in the implant  10  such that, once expanded, the implant  10  provides ample room nearer the proximal end of the implant (such as at least partially within the frame  100 , for example) for the post-packing of bone growth promoting materials. For example, the proximal wall  110  of the frame  100  may define a proximal aperture  111  which may be suitable for receiving at least part of an insertion instrument  30  through which bone growth promoting material may be introduced into a proximal portion of the implant  10 . Furthermore, the distal wall  120  of the frame may define a distal aperture  121  (see  FIG. 2 , for example) that is adapted to receive a plug  130 . As described further herein, the plug  130  may be movably disposed in the distal aperture  121  of the frame. 
     The expandable spinal implant  10  may further comprise a first endplate  140  operably engaged with the frame  100  and configured to expand outward from the frame  100  when the plug  130  is moved in a distal direction D (See  FIGS. 3-4 ). Furthermore, in some embodiments, the expandable spinal implant  10  may comprise opposing first and second endplates  140 ,  150  as shown generally in  FIGS. 1-2 . In some such embodiments of the expandable spinal implant  10 , the second endplate  150  may be operably engaged with the frame  100  and configured to expand outward from the frame  100  when the plug  130  is moved in a distal direction D. Furthermore, as shown in  FIG. 1 , the second endplate  150  may be disposed about the frame  100  and opposing the first endplate  140 , wherein the first endplate  140  and the second endplate  150  extend from a proximal end of the implant  10  to a distal end of the implant  10  (along the length L of the implant  10 ) and at least partially enclose the frame  100 . A similar structure is also shown in implant  20  of  FIGS. 5-8 , wherein endplates  240 ,  250  cooperate to at least partially enclose the frame  200  (see  FIG. 5 , for example). The various endplates  140 ,  150 ,  240 ,  250  may be provided with convex surfaces in multiple planes to conform to adjacent vertebral body endplates (see V 1 , V 2  as shown in  FIGS. 14 and 16 ). It should be understood that the surfaces of the various endplates  140 ,  150 ,  240 ,  250  could also be constructed with a convexity in only one plane or without any convexities. Furthermore, the vertebral body V 1 , V 2  contacting surfaces of endplates  140 ,  150 ,  240 ,  250  may be provided with various anti-migration and/or osseointegration features including, but not limited to: ridges, teeth, pores, and coatings (including but not limited to porous titanium coatings such as those provided on Capstone PTC™ implants available from Medtronic plc). 
       FIG. 18  shows an embodiment of an expandable spinal implant  10  comprising only a first endplate  140  operably engaged with the frame  100  and configured to expand outward from the frame  100  when the plug  130  is moved in a distal direction D (See  FIGS. 3-4 ). In the embodiment of  FIG. 18 , the second endplate  150  may be integrally formed with the frame  100  and/or non-movable relative to the frame  100  such that as the plug  130  is moved distally, only the first endplate  140  (hinged to the frame  100  via pin  154 ). In such embodiments, the distal head portion  135  may be modified to engage the movable first endplate  140  and the static second endplate  150 . For example, as shown generally in  FIG. 3A , the movable first or second endplate  150  (and/or the complementary endplate  140 ) may comprise a ramped surface  153  upon which ramped surface  136  of the distal head portion  135  may bear as the implant  10  is expanded. The ramp  136 / 153  mechanism may cooperate with a paired lateral post  137  and track  145  system (see  FIG. 18 ) in order to optimize the opening and/or expansion of the implant  10 . 
     Referring generally to  FIGS. 1-4 , the endplates  140 ,  150  may be operably engaged with the frame  100  via a hinge mechanism located near or on the proximal wall  110  of the frame  100 . For example, pins  154  may be provided that engage corresponding pin apertures  112  defined in the frame  100  such that the endplates are operably engaged with and/or hinged relative to the frame  100  such that the endplates  140 ,  150  may be expandable relative to the frame  100  by virtue of the cooperation of the pins  154  and pin apertures  112  as the plug  130  is moved distally D relative to the frame  100  of the implant  10 . Similar hinge mechanisms are also shown relative to the embodiments of  FIGS. 7-8  comprising pins  154  engaged with pin apertures  212  to connect frame  200  with endplates  240 ,  250  in a hinged relationship. While multi-part mechanical hinges are shown in some of the pictured embodiments, it should be understood that other types of hinge and/or connection mechanisms may also be used to operably engage the frame  100  with the expandable endplates  140 ,  150  of the implant. For example, in some embodiments, a “living hinge” may be utilized wherein the endplates  140 ,  150  are at least partially integrally formed with the frame  100  at the hinge point but with cut-outs or flex points that allow the endplates  140 ,  150  to rotate about the hinge connection. In summary, the frame  100  and endplates  140 ,  150  may be operably engaged in a number of different ways including but not limited to: integral connections, separable connections, mechanically fixed connections using fastener or adhesives, releasable connections (including, but not limited to keyways and partially open hinges), and other connection types. In some embodiments, the frame  100  and endplates  140 ,  150  may be integrally formed using additive manufacturing techniques such as 3D printing or sintering laser/beam melting, casting, extruding, or machined in an integral form using subtractive manufacturing techniques from one or more stock materials. 
     In some embodiments, the frame  100  of the expandable spinal implant  10  further comprises at least one side wall  102  engaged with the proximal wall  110  and the distal wall  120 . As shown generally in  FIG. 3 , the side wall  102  or walls  102 ,  104  may be configured to space the proximal wall  110  and the distal wall  120  along a longitudinal axis (running substantially and/or nearly parallel to the length L) of the expandable spinal implant  10 . The side walls  102 ,  104  may also be configured to contain bone growth promoting material in a proximal portion of the implant  10  that may be pre-packed or post-packed into the implant  10  via the proximal aperture  111 . The side walls  102 ,  104  may cooperate with the proximal wall  110  and the distal wall  120  to create a four-sided frame  100  (that may define side apertures as shown in  FIGS. 3-4 ). In some such embodiments, the frame may define internal threads  103  configured to cooperate with an outer threaded surface  131  of the plug  130  when the plug  130  is positioned generally proximally relative to the distal wall  120  of the frame  100 . 
     The frame  100  may be especially useful in some embodiments for placing the plug  130  in a substantially distal position relative to the overall length L of the implant  10  such that a distal portion of the implant (within a volume substantially encompassed by the frame  100 , for example) may be open and free to be filled (or “post-packed” with bone-growth promoting materials after the implant has been placed in a disc space between vertebral bodies (see, for example, the placement of implant  10 , between vertebral bodies V 1  and V 2 , shown in  FIGS. 14 and 16 ). As described herein with respect to  FIGS. 1, 3, 5 and 7 , the implant  10 ,  20  may comprise or define a length L along a longitudinal axis thereof extending from a proximal end  110  thereof to a distal end  144  thereof. In some such embodiments, the distal wall  120  of the frame may be disposed at least one third ( 1 / 3 ) of the length L (i.e. at a position spaced distally from the proximal end  110  by a distance Was shown generally in  FIGS. 3 and 7 ). In other embodiments the distal wall  120  of the frame may be disposed at other fractions of the length L (i.e. at a position spaced distally from the proximal end  110  by a distance W as shown generally in  FIGS. 3 and 7 ) including, but not limited to, at least 1/10, ⅛, ⅕, ¼, ⅖, ¾, ⅞ and 9/10. In other embodiments, the distal wall  120  of the frame may be disposed at a position spaced distally from the proximal end  110  by a distance W as shown generally in  FIGS. 3 and 7  wherein the distance W ranges from 0 to 100 percent of the distance L, but in some instances distance W is at least 0.25 of the distance L to provide space in a proximal portion of the implant  10  for bone growth promoting material to be adequately post-packed into the area defined at least in part by distance W when the plug  130  is moved distally. Therefore a proximal portion of the implant  10  (such as an internal volume defined at least in part by frame  100 ) may be left substantially open and in fluid communication with the proximal aperture  111  of the frame  100  such that a bone growth promoting material may be placed through the proximal aperture  111  of the frame  100  after the plug  130  is moved in a distal direction D (see  FIG. 3  showing the plug in an initial position, and  FIG. 4  showing the plug moved distally to reveal a frame  100  volume left open and in fluid communication with the proximal aperture  111 ). 
     In other embodiments, as shown relative to the implant  20  in  FIGS. 5-8 , a single side wall  204  may replace the dual-wall embodiments of  FIGS. 1-4  to space the distal wall  120  of the frame  100  from the proximal wall  110  of the frame. In some such embodiments with a single side wall  204 , the frame  200  may be substantially open on one side of the implant  10  to allow for post-insertion packing of bone growth promoting material via the open side of the frame  200 . The “open” or wall-less side of the frame  200  (which may be positioned generally opposite the side wall  204 ) may also be used to direct and/or contain bone growth promoting material that may be introduced to the implant implantation site through the proximal aperture  211  of the frame  200  of the implant  20 . As with the “closed” embodiment having two side walls  102 ,  104 , the single side wall  204  embodiments may also define internal threads  203  configured to cooperate with an outer threaded surface  231  of the plug  230  when the plug  230  is positioned generally proximally relative to the distal wall  220  of the frame  200 . 
     In various embodiments, the plug  130 ,  230  provided in the expandable spinal implant  10 ,  20  may comprise a threaded outer surface  131  (see  FIG. 1 , for example), and the distal aperture  121  may comprise a complementary threaded inner surface operably engaged with the threaded outer surface  131  of the plug  130 . The threaded outer surface  131  of the plug may be disposed on a proximal end of the plug  130  such that the plug  130  moves distally D as shown in  FIG. 4  when the plug  130  is rotated relative to the distal wall  120  of the frame  100 . In some embodiments, as shown generally in  FIGS. 4 and 8 , the frame  100  may comprise a sidewall  104  connecting the distal wall  120  and the proximal wall  110 , wherein the at sidewall  104  comprises a sidewall threaded surface  103  configured to be operably engaged with the threaded outer surface  131  of the plug  130  (especially when the plug is still positioned proximally relative to the frame  100 ). An alternate embodiment of the sidewall threaded surface  203  is also shown in  FIG. 8 . Furthermore, the plug  130  may also comprise a distal head portion  135  configured to urge the endplate  140  away from the frame  100  with the plug  130  is moved in a distal direction D. The distal head portion  135  may be configured in some embodiments (as shown generally in  FIGS. 1-4 ) with a separate structure having ramped surfaces  136  that may be configured to interface with complementary ramped surfaces on the endplates  140 ,  150 . For example, as shown in  FIG. 3A , the endplate  150  (and the complementary endplate  140 ) may comprise ramped surface  153  upon which ramped surface  136  of the distal head portion  135  may bear as the implant  10  is expanded. The ramp  136 / 153  mechanism may cooperate with the lateral post  137  and track  155  system in order to optimize the opening and/or expansion of the implant  10 . For example, the ramp  136 / 153  mechanism may provide a leading expansion mechanism that is subsequently assisted by the lateral post  137  and track  155  system to expand the implant as the plug  130  is moved. Furthermore, the lateral post  137  and track  155  system may also render the expansion of the implant  10  reversible by pulling the endplates  140 , 150  inward towards the frame  100  along a relatively smooth ramped incline provided by the ramp  136 / 153  mechanism. Furthermore, the plug  130  may comprise separate connecting elements  132 ,  133  such that the distal head portion  135  of the plug may be distally movable relative to the frame  100  without rotation while a proximal portion of the plug  130  (such as that portion defining the threaded outer surface  131 ) is able to freely rotate in the distal aperture  121  of the distal wall  120  of the frame  100 . 
     In other embodiments, as shown generally in  FIGS. 5-8 , the plug  230  may include a distal head portion  235  comprising a tapered cylinder. In some such embodiments, the distal head portion  235  may be configured to rotate with the plug  230  and/or move only distally D relative to the frame  100  as a proximal portion (defining the outer threaded surface  231 , for example) is rotated relative to the frame  100  to drive the plug  230  in the distal direction D. According to some such embodiments, the distal head portion  235  may be configured to cooperate with a contoured bearing surface  253  (comprising in some instances a ramp and/or frusto-conical concave surface) defined on an interior surface of the endplates  240 ,  250 . 
     The distal head portions  135 ,  235  may be configured in various ways to provide a lead-in or gradual taper in order to allow for an easier interaction between the plug  130 ,  230  and the endplates  140 ,  150  or  240 ,  250 . For example, as shown generally in the partially disassembled view of  FIG. 3  (where the first endplate  140 , is removed), the distal head portion  135  comprises a ramp  136  or wedge suitable for urging a complementary ramped or contoured surface  153  on the inside of the endplates  140 ,  150  (see  FIG. 3A , showing an isolated view of one endplate  150  with an exemplary ramp  153  formed therein) so as to gradually move the endplate  140  away from the frame  100  as the plug  130  is advanced distally along the length L of the implant  10 . Similarly, in the embodiments shown in  FIGS. 5-8 , the distal head portion  235  may be tapered to provide a lead-in or frustoconical shape that may be optimized with a taper that allows for a mechanical advantage to be realized when urging the endplates  240 ,  250  away from the frame  200 . The resulting open configuration of the implant  20  is shown, for example, in  FIG. 6 . Furthermore, it should be understood that a variety of ramp and/or taper configurations may be used to optimize the interaction of the plug  130 ,  230  with the endplates  140 ,  150  or  240 ,  250 . Such configurations may include, but are not limited to: sequential ramps or tapered frustoconical surfaces with varying angles; shallow angle sequential ramps or tapered frustoconical surfaces leading into higher angle sequential ramps or tapered frustoconical surfaces (increasing the mechanical advantage once an initial expansion of the implant  10  has been achieved), as well as other opening mechanisms (such as the lateral post  137  and track  155  system shown generally in  FIGS. 2-4  that may combine to assist the ramps  136  (and  153 , See  FIG. 3A ) in expanding the implant  20 ). 
     As shown in  FIGS. 2-4 , in some embodiments of the expandable spinal implant  10 , the distal head portion  135  may comprise a lateral post  137  extending from the distal head portion  135  of the plug  130  and configured for cooperating with a corresponding channel  145 ,  155  defined in the endplates  140 ,  150 . The channels may be angled or partially angled to provide additional mechanisms for assisting in the expansion of the implant  10  as the plug  130  is advanced distally along the length L of the implant  10 . Referring more particularly, to  FIG. 2 , the first endplate  140  may define at least one lateral channel  145  configured to receive the lateral post  137  such that when the plug  130  is moved in a distal direction along the length L, the lateral post  137  of the distal head portion  135  is moved in a first direction in the lateral channel  145  to expand the first endplate  140  outward from the frame  100 . The post  131  and channel  145  mechanism may also aid in making the implant  10  expansion substantially reversible such that when the plug  130  is moved in a proximal direction (i.e. towards the distal wall  110  of the frame  100 ) the lateral post  137  of the distal head portion  135  is moved in a second direction in the lateral channel  145  to contract the first endplate  140  towards the frame  100  (which may result in the implant  10  returning to the closed or unexpanded configuration shown generally in  FIG. 1 ). This reversible feature, combined with the threaded mechanism of the plug  130  renders the implant  10  capable of being incrementally expanded or contracted through a substantially infinitely adjustable range of motion (bounded only by the length of the plug  130  and the corresponding bearing surfaces (see  253 ,  FIG. 6 , for example) defined by the endplates of the implant  10 )). 
     In some embodiments, the expandable spinal implant system  10 ,  20  may be configured to be operable with and/or inserted by an insertion instrument  30  (see generally  FIG. 17  for example). In some such embodiments, as shown in  FIG. 9 , the expandable spinal implant  10  may comprise a frame  100  comprising a proximal wall  110  and a distal wall  120 . The proximal wall  110  may further define a proximal aperture  111  and the distal wall  110  may further define a distal aperture  121 . As described herein, one or both of the proximal aperture  111  and the distal apertures  121  may be internally threaded to receive other threaded components. In some embodiments, the proximal wall  110  may be adapted to receive an insertion instrument  30  (or in some cases an inner cannula  320  of the insertion instrument  30  as shown in  FIG. 9 ). 
     As described herein, the expandable spinal implant  10  may also comprise a plug  130  movably disposed in the distal aperture  121 , wherein the plug  130  comprises an interface  134  adapted to be operably engaged by at least a portion of the insertion instrument  30  to move the plug  130 . For example, in some embodiments, the insertion instrument  30  may comprise a driver shaft  330  with a driver on a distal end thereof (such as a hexalobular driver tip). The distal end of the driver shaft  330  may be engaged with the interface  134  of the plug  130  to rotate the plug in the distal aperture  121  of the frame  100  in order to expand the implant  10 . As described herein, expansion of the implant  10  may be achieved by the moving the endplates  140 ,  150  that are operably engaged by the frame  100  and configured to move relative to the frame  100  when the plug  130  is moved by the insertion instrument  30  (or the driver shaft  330  thereof). 
     As shown generally in  FIG. 17 , the driver shaft  330  may be coxially disposed inside an inner cannula  320  of the insertion instrument  30 . Furthermore, both the driver shaft  330  and the inner cannula  320  may be coaxially disposed inside a cannula  330  of the insertion instrument  30 . Each of the driver shaft  330 , inner cannula  320  and cannula  310  may further be provided with various manipulation components  330 ′,  320 ′ and  310 ′ respectively, so that the various components of the insertion instrument  30  may be operated and/or selectively manipulated independent of one another to perform various functions relative to the implant  10  (as described further herein). 
     As described herein and shown in the embodiments of  FIGS. 3 and 7 , the frame  100 ,  200  may further comprise at least one side wall  104 ,  204  engaged with the proximal wall  110  and the distal wall  120  of the frame  100 . The side wall  104 ,  204  may be configured to space the proximal wall  110  and the distal wall  120  of the frame  100  along a longitudinal axis (extending parallel to the length L) of the implant  10 ,  20 . In some embodiments, as shown in  FIG. 3 , the frame  100  comprises a pair of side walls  102 ,  104  spaced laterally apart and engaged with the proximal wall  110  and the distal wall  120  of the frame  100  to form a substantially closed area adapted to receive and/or contain a bone growth promoting material that may be placed through the proximal aperture  111  of the frame  100 . In some embodiments, the cannula  310  or inner cannula  320  of the insertion instrument  30  may be configured to convey bone growth promoting material through the insertion instrument  30  and into the area defined by the frame  100  when the implant  10  is in the expanded position (see  FIG. 2 , for example, showing the plug  130  moved distally forward and out of the proximal area of the implant  10  defined by the frame  100 ). 
     In some embodiments the frame  100  may be substantially “closed” with sidewalls as shown generally in  FIGS. 9-12 . In other embodiments, the frame  100  may comprise a pair of sidewalls  102 ,  104  with lateral apertures as shown generally in  FIGS. 1-4 . In other embodiments, as shown generally in  FIGS. 5-8 , the frame  200  may comprise a unilateral or single side wall  204  forming a frame  200  with one “open” lateral side. In some such embodiments as shown in  FIG. 8 , the frame  200  may be adapted to an least partially contain a bone growth promoting material BG that may be placed through the proximal aperture  211  of the frame  200  and/or direct the bone growth promoting material BG outside of the expandable spinal implant  20  in a lateral direction between the proximal wall  210  and the distal wall  220  of the frame  200 . 
       FIGS. 9-12  show various configurations of an implant  10  embodiment in use with an insertion instrument  30  to form an expandable spinal implant system according to one embodiment. As shown generally in  FIG. 9 , the system may comprise an insertion instrument  30  comprising a cannula  310  (which may include an inner cannula  320  and an outer cannula  310  as described herein) and a driver shaft  330  (see  FIG. 10  and  FIG. 17 ) removably and rotatably disposed within the cannula  310 . The system may also further comprise an expandable spinal implant  10  configured to be operably engaged with the insertion instrument  30  using a variety of mechanisms. As described herein, the implant  10  comprises a frame  100  comprising a proximal wall  110  and distal wall  120 , wherein the proximal wall  110  defines a proximal aperture  111  and the distal wall  120  defines a distal aperture. The proximal wall  110  may be configured to receive a distal end of the cannula  310  (or the middle cannula  320 ) for manipulating the expandable spinal implant  10 . For example, as shown in  FIG. 9 , the cannula  310  may comprise prongs  311  configured for insertion into complementary receptacles  114  defined by the proximal wall  110  of the frame  100 . In other embodiments, the prongs  311  may interact with tabs or slots defined by the endplates  140 ,  150 . The prongs  311  may interact with the receptacles  114  to enable a surgeon to manipulate the implant  10  effectively as it is engaged with a distal end of the insertion instrument. Furthermore, in some embodiments, the inner cannula  320  may comprise a threaded tip  321  configured for operably engaging threaded inner surface of the proximal aperture  111  of the frame  100 . In some such embodiments, the prongs  311  of the outer cannula may serve as an effective counter-torque device (preventing rotation of the implant  10  relative to the insertion instrument  30 ) as the inner cannula  320  is rotated to engage the proximal aperture  111  of the frame  100 .  FIG. 17  shows the insertion instrument  30  in relation to the implant  10  including manipulation components  330 ′,  320 ′ and  310 ′ of the insertion instrument. For example, handle  310 ′ of the outer cannula  310  may be used to stabilize and/or manipulate the implant  10  even as the knob  320 ′ of the inner cannula  320  is rotated within the outer cannula  310  such that the threaded tip  321  may be engaged with the proximal aperture  111  of the frame  100  without rotating the implant  100 . 
     As described herein, the implant  10  may be configured for expansion by virtue of a plug  130  movably disposed in the distal aperture  120  of the frame  100 . In some embodiments, the plug comprises a threaded outer surface  131  configured to be engaged with a complementary inner threaded surface of the distal aperture  120 . In some embodiments, as shown in  FIG. 9 , the plug  130  may comprise an interface  134  configured to be operably engaged by a distal end of a driver shaft  330  to move (by threaded rotation, for example) the plug  130  relative to the frame. The driver shaft  330  may be coaxially placed within the cannula  310  and/or the inner cannula  310  and rotatable therein using the driver proximal end  330 ′ of the driver shaft  330 . The driver proximal end  330 ′ may comprise a keyed or faceted surface configured for engagement with a quick-release handle (not shown) or a powered driver (not shown) for rotating the driver shaft  330 . Furthermore, the plug interface  134  may comprise a drive receptacle configured to cooperate with a distal end of the driver shaft. The drive connection between the driver shaft  330  and the plug interface  134  may comprise a variety of drive interfaces including but not limited to: multi-lobular drives; hexalobular drives; cross or Phillips head drives; straight or “flat head” drives; square or other polygonal drives; and/or combinations thereof. 
     As described herein, the movement of the plug  130  facilitated by the driver shaft  310  within the cannula  310  (and, in some cases the inner cannula  320 ) may further cause the movement of an endplate  140 ,  150  operably engaged with the frame  100  of the implant  10  relative to the frame  100  when the plug  130  is moved by the insertion instrument  30 . Thus the insertion instrument  30  (or the driver shaft  330  and driver proximal end  330 ′) may be used to expand the endplates  140 ,  150  relative to the frame  100  in order to selectively expand the implant  10  and/or impart a lordotic movement in adjacent vertebral bodies V 1 , V 2  as shown generally in  FIGS. 14 and 16 . The length of the driver shaft  330  may be adjusted to account for the distal placement of the distal wall  120  of the frame  100  relative to the length L of the implant  10 . For example, the driver shaft  330  may be provided with a length that substantially exceeds that of the cannula  310  and/or inner cannula  320  so that the driver proximal end  330 ′ remains accessible and engaged with a handle or powered driver even when the driver shaft  330  remains engaged with the plug  130  of the implant  10  when the implant is in the fully expanded condition (see  FIGS. 14 and 16 ). This feature may be important in situations where a surgeon wishes to reverse the expansion of the implant  10  as described further herein with respect to the post  131  and channel  145  mechanisms of particular implant  10  embodiments. 
     According to various embodiments, the driver shaft  330  may also be configured to be removable from the cannula  310  (and/or the inner cannula (if employed)), such that after the plug  130  of the implant  10  has been moved distally relative to the frame  100 , a bone growth promoting material BG may be introduced into the frame  100  of the expandable spinal implant  10  through the cannula  310  (and/or through the concentric inner cannula  320 , when used). The bone growth promoting material BG may be tamped or urged through the cannula  310  or inner cannula  310  using the driver shaft  330  or other tamp and/or rod (not shown) sized for slidable insertion through the cannula  310  and/or inner cannula  310 . A funnel (not shown) or other attachment may also be inserted into a proximal end of the cannula  310  or inner cannula  320  (such as at the point near the proximal end or knob  320 ′ of inner cannula  320 , as shown in  FIG. 17 ) to facilitate the introduction of the bone growth promoting material BG into the cannula  310  and/or inner cannula  320 . 
       FIGS. 9-12  depict exemplary procedural steps for the use of the implant system in one embodiment. For example,  FIG. 9  shows an unexpanded implant  10  attached to insertion device  30  using the prongs  311  of the cannula  310  and the distal end  321  of inner cannula  320 . The plug  130  is shown engaged with the distal aperture of distal wall  120  of the frame and the plug interface  134  is visible. In  FIG. 10 , the driver shaft  330  is shown extended through cannula  310  and inner cannula  320  and engaged with the plug interface  134 . Referring to  FIG. 17 , the driver proximal end  330 ′ may be rotated at this step to drive the plug  130  forward to expand the endplates  140 ,  150  relative to the frame  100 .  FIG. 11  shows the result of the interaction of the driver shaft  330  with the plug  130  and the distal movement of the plug  130  relative to the distal wall  120  of the frame  100  to expand the endplates  140 ,  150  relative to the frame  100  of the implant  10 .  FIG. 12  shows the insertion device  30  still engaged with the implant  10  but with the driver shaft  330  removed from the cannula  310  and inner cannula  320 , leaving the cannulas open for the introduction of bone growth promoting material BG through the insertion instrument  30  and into a proximal portion of the implant  10  defined generally by the now-open interior of the frame  100 . 
     Referring to exemplary  FIGS. 13-16 , spinal implant system  10 ,  30  can be employed with a surgical arthrodesis procedure, such as, for example, an interbody fusion for treatment of an applicable condition or injury of an affected section of a spinal column and adjacent areas within a body, such as, for example, intervertebral disc space between a vertebra V 1  and a vertebra V 2 . In some embodiments, spinal implant system  10 ,  30  can include an intervertebral implant that can be inserted with intervertebral disc space to space apart articular joint surfaces, provide support and maximize stabilization of vertebrae V 1 , V 2 . In some embodiments, spinal implant system  10 ,  30  may be employed with one or a plurality of vertebra. 
     A medical practitioner obtains access to a surgical site including vertebrae V 1 , V 2  such as through incision and retraction of tissues. Spinal implant system  10 ,  30  can be used in any existing surgical method or technique including open surgery, mini-open surgery, minimally invasive surgery and percutaneous surgical implantation, whereby vertebrae V 1 , V 2  are accessed through a mini-incision, retractor, tube or sleeve that provides a protected passageway to the area. In one embodiment, the components of spinal implant system  10 ,  30  are delivered through a surgical pathway to the surgical site along a surgical approach into intervertebral disc space between vertebrae V 1 , V 2 . Various surgical approaches and pathways may be used.  FIG. 13  shows an example of a typical posterior lumbar interbody fusion (PLIF) approach using the spinal implant system  10 ,  30  wherein a pair of implants  10  may be delivered, expanded to impart or restore a lordotic curve (see generally  FIG. 14 ), and then post-packed with bone growth promoting material BG after the removal of the driver shaft  330  from the insertion instrument  30 . As shown in  FIG. 15 , unilateral approaches such as a transforaminal lumbar interbody fusion (TLIF) approach may also be used to place the implant in a substantially oblique position relative to the vertebrae V 1 , V 2 . In such procedures the distal end  144  of the endplates  140 ,  150  may be shaped so that the implant  10  fits within the intervertebral space defined by the extents of the vertebral body V 2  as shown in  FIG. 15 . Furthermore, in oblique placement applications the implant  10  endplates  140 ,  150  may also be provided with complementary oblique contact surfaces shaped to better impart and/or restore a lordotic curve as the implant  10  is expanded as shown generally in  FIG. 16 . Furthermore, the endplates  140 ,  150  of the implant may be provided with a variety of ridges, teeth, coatings or other surface treatments suitable for interacting with and/or securing relative to the adjacent vertebrae V 1 , V 2 . 
     As will be appreciated by one of skill in the art, a preparation instrument (not shown) may be employed to remove disc tissue, fluids, adjacent tissues and/or bone, and scrape and/or remove tissue from endplate surfaces of vertebra V 1  and/or endplate surface of vertebra V 2  in preparation for the procedures utilizing the system  10 ,  30 . In some embodiments, the size of implant  10  is selected after trialing using trialing instruments (not shown) that may approximate the size and configuration of the system  10 ,  30  (as shown in  FIG. 17 , for example). In some embodiments, such trials may be fixed in size and/or be fitted with expansion mechanisms similar to the various implant  10 ,  20  embodiments described herein. In some embodiments, implant  10  may be visualized by fluoroscopy and oriented before introduction into intervertebral disc space. Furthermore, the insertion instrument  30  and implant  10  may be fitted with fiducial markers to enable image guided surgical navigation to be used prior to and/or during a procedure. 
     In some embodiments as shown generally in  FIGS. 13 and 15 , implant  10  provides a footprint that improves stability and decreases the risk of subsidence into tissue. In some embodiments as shown generally in  FIGS. 14 and 16 , implant  10  provides angular correction, height restoration between vertebral bodies, decompression, restoration of sagittal and/or coronal balance and/or resistance of subsidence into vertebral endplates. In some embodiments, implant  10  engages and spaces apart opposing endplate surfaces of vertebrae V 1 , V 2  and is secured within a vertebral space to stabilize and immobilize portions of vertebrae V 1 , V 2  in connection with bone growth for fusion and fixation of vertebrae V 1 , V 2 . 
     Components of spinal implant system  10 ,  30  including implant  10  can be delivered or implanted as a pre-assembled device or can be assembled in situ. Components of spinal implant system  10 ,  30  including implant  10  may be expanded, contracted, completely or partially revised, removed or replaced in situ. In some embodiments, one or all of the components of spinal implant system  10 ,  30  can be delivered to the surgical site via mechanical manipulation and/or a free hand technique. 
     In one embodiment, spinal implant system  10 ,  30  includes a plurality of implants  10  (see  FIG. 13  for one example). In some embodiments, employing a plurality of implants  10  can optimize angular correction and/or height restoration between vertebrae V 1 , V 2 . The plurality of implants  10  can be oriented in a side by side engagement, spaced apart and/or staggered. 
     In some embodiments, spinal implant system  10 ,  30  includes an agent, including but not limited to the bone growth promoting materials BG described herein, which may be disposed, packed, coated or layered within, on or about the components and/or surfaces of spinal implant system  10 ,  30 . In some embodiments, the agent may include bone growth promoting material to enhance fixation of implant  10  with bony structures. In some embodiments, the agent may include one or a plurality of therapeutic agents and/or pharmacological agents for release, including sustained release, to treat, for example, pain, inflammation and degeneration. 
     In one embodiment, implants  10 ,  20  may include fastening elements, which may include locking structure, configured for fixation with vertebrae V 1 , V 2  to secure joint surfaces and provide complementary stabilization and immobilization to a vertebral region. In some embodiments, locking structure may include fastening elements, such as, for example, rods, plates, clips, hooks, adhesives and/or flanges. In some embodiments, the components of spinal implant system  10 ,  30  can be used with screws to enhance fixation. The components of spinal implant system  10  can be made of radiolucent materials such as polymers. Radiopaque markers may be included for identification under x-ray, fluoroscopy, CT or other imaging techniques. 
     In some embodiments, the use of microsurgical, minimally-invasive and image guided technologies may be employed to access, view and repair spinal deterioration or damage, with the aid of spinal implant system  10 ,  30 . Upon completion of the procedure, the non-implanted components, surgical instruments and assemblies (such as insertion instrument  30 ) of spinal implant system  10 ,  30  may be removed and the incision is closed. In some embodiments, the various instruments (such as the insertion instrumentation disclosed generally herein in  FIG. 9  and related figures) disclosed may be provided with fiducial markers or other elements suitable for use with surgical navigation systems (including, but not limited to the STEALTHSTATION® Navigation system available from Medtronic plc), such that a surgeon may view a projected trajectory or insertion pathway of the implants  10 ,  20  relative to a patient&#39;s anatomy in real time and/or in near-real time. 
     It will be understood that the various independent components of the expandable spinal implants  10 ,  20 , systems and insertion instruments  30  described herein may be combined in different ways according to various embodiments. As a non-limiting example, the notches  114  shown in  FIGS. 5-8  with respect to implant  20  may also be added to a proximal end of the implant  10  shown in  FIGS. 1-4 . As a further non-limiting example, the dual apertures  241   a ,  241   b ,  251   a ,  251   b  shown in  FIGS. 5-8  with respect to the endplates  240 ,  250  of implant  20 , may also be added to the endplates  140 ,  150  of the implant  10  shown in  FIGS. 1-4 . 
     It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplification of the various embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims in this document.