Patent Publication Number: US-2022218493-A1

Title: Devices and methods for stabilization of the spine using transpedicular approaches

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 63/135,740 filed Jan. 10, 2021, the entirety of which is hereby incorporated by reference herein. Further, the entirety of U.S. application Ser. No. 15/048,225, filed on Feb. 19, 2016 and published on Jan. 19, 2017 as U.S. Publ. No. 2017/0014243, is incorporated by reference herein and made a part of this application. 
    
    
     BACKGROUND 
     Field 
     This application relates generally to devices, systems and methods for the treatment of the spine, and more specifically, to access into an intervertebral space, spinal implants, pedicle screws, fixation systems and related tools, systems and methods. 
     Description of the Related Art 
     Surgical approaches to the intervertebral space are utilized for a variety of indications and purposes, such as, for example, biopsy (e.g., for evaluation of possible infection, other pathology, etc.), discectomy (e.g., for decompression of nerve roots, to prepare for subsequent fusion procedures, etc.), disc height restoration or deformity correction, disc replacement or repair (e.g., annular repair), discogram, gene therapy and/or other procedures or treatments. 
     Various approaches are currently used to access the interbody or intervertebral space of a patient&#39;s thoracic, lumbar and sacral spine. These include anterior approaches (ALIF) (e.g., open, mini-open retroperitoneal, etc.), lateral approaches (e.g., costotranversectomy, extreme lateral, etc.), posterolateral approaches (e.g., posterior lumbar interbody fusion (PLIF), transforaminal lumbar interbody fusion (TLIF), etc.) and axial approaches (e.g., axial lumbar interbody fusion). Further, many minimally invasive and percutaneous approaches rely on radiographic landmarks with or without direct view to access a targeted interbody space. In addition, many, if not all, of these currently used approaches require violation of the disc annulus to access the disc space. 
     Fusion surgery of the thoracic, lumbar and sacral spine is often performed for a variety of indications, including degenerative joint disease, deformity, instability and/or the like. Typically, traditional fusion approaches involve relatively large, open incisions performed under direct vision. Minimally invasive surgical techniques and corresponding surgical implants have become more popular in an attempt to reduce morbidity and generally improve outcomes. Multiple variations of percutaneous systems (e.g., pedicle screw and rod systems, facet screw systems, etc.) have been developed. Such systems can allow for instrumentation placement with fluoroscopic guidance (e.g., using radiographically recognizable body landmarks) and/or other imaging technologies. Current fusion techniques, including those that utilize open and minimally invasive approaches, often require direct visualization. However, such techniques typically involve traversing spaces that are occupied by neural elements. Thus, these neural elements need to be retracted or otherwise moved during the execution of spinal procedures that precede implantation (e.g., annulotomy, discectomy, disc space and/or vertebral endplate preparation, etc.). Retraction of sensitive neural elements can also be required during the delivery of an implant to the spine. 
     These approaches typically require contact and retraction of nerve roots and/or sensitive visceral organs, blood vessels and/or other sensitive portions of the anatomy. Contact and retraction of these structures can place them at risk, thereby increasing the likelihood of complications and damage to a patient. Accordingly, a need exists for improved approaches for spinal fusion and/or access to intervertebral spaces. 
     SUMMARY 
     According to some embodiments, a method of fusing a first vertebra to a second vertebra, said second vertebra being immediately adjacent and above the first vertebra, the method comprises creating a passage from a posterior end of a pedicle of the first vertebra through a superior endplate of the first vertebra, such that the passage extends into an intervertebral space located generally between the first and second vertebrae, removing native tissue located within the intervertebral space by advancing a tissue removal tool through the passage and selectively moving said tissue removal tool within the intervertebral space, and delivering an implant through the passage, wherein the implant is expandable and configured to promote fusion between the superior endplate of the first vertebra and an inferior endplate of the second vertebra. 
     According to some embodiments, the method further includes providing a grafting material through the passage to further promote fusion. In some embodiments, the passage created through the first vertebra is generally linear. In some arrangements, the method is performed minimally invasively. 
     According to some embodiments, the implant comprises an expandable implant (e.g., balloon, sac, pliable or flexible members, etc.). 
     According to some embodiments, removing native material comprises removing at least one of disc material and a surface of an endplate of the first vertebra or the second vertebra. In some embodiments, the tissue removal tool comprises an expandable head portion, said head portion being configured to assume a collapsed positioned during advancement through the passage and being configured to selectively assume an expanded position within the intervertebral space. 
     According to some embodiments, the method further includes inserting an access device within the passage to facilitate the movement of tools or devices through the passage. 
     According to some embodiments, the method additionally comprises inserting a first bone screw through the first vertebra and inserting a second bone screw through the second vertebra. In some arrangements, the method further comprises connecting the first bone screw to the second bone screw using a rod or other connector. 
     According to some embodiments, the implant is positioned along a distal end of an implant tube assembly, wherein the implant tube assembly is configured to be removably positioned within the passage, wherein the implant tube assembly is further configured to direct graft material through an interior opening of the implant tube assembly and into the implant, the implant being configured to expand when graft material is inserted therein. In some embodiments, the implant is configured to be separated from a remaining portion of the implant tube assembly once the implant has received sufficient graft material. 
     According to some embodiments, graft material is configured to be inserted through the passage using a graft delivery tool. In some arrangements, the graft delivery tool is configured to be operated manually or using a mechanical advantage. 
     According to some embodiments, a method of fusing a first vertebra to a second vertebra, wherein the second vertebra is immediately adjacent and above the first vertebra, comprises creating a passage from a posterior end of a pedicle of the first vertebra through a superior endplate of the first vertebra, such that the passage extends into an intervertebral space located generally between the first and second vertebrae. The method further comprises removing native tissue located within the intervertebral space by advancing a tissue removal tool through the passage and selectively moving said tissue removal tool within the intervertebral space, and delivering at least one of an implant and a grafting material through the passage, wherein said implant or grafting material is configured to promote fusion between the superior endplate of the first vertebra and an inferior endplate of the second vertebra. In some embodiments, the method comprises advancing a first bone screw through the passage, such that a distal end of the first bone screw extends at least partially into the intervertebral space. 
     According to some embodiments, a method of fusing a first vertebra to a second vertebra, wherein the second vertebra is immediately adjacent and above the first vertebra, comprises creating a passage from a posterior end of a pedicle of the first vertebra through a superior endplate of the first vertebra, such that the passage extends into an intervertebral space located generally between the first and second vertebrae. The method further comprises removing native tissue located within the intervertebral space by advancing a tissue removal tool through the passage and selectively moving said tissue removal tool within the intervertebral space, and delivering at least one of an implant and a grafting material through the passage, wherein said implant or grafting material is configured to promote fusion between the superior endplate of the first vertebra and an inferior endplate of the second vertebra. In some embodiments, posterior fixation of the first and second vertebrae is performed in conjunction with the above procedure (and/or any other procedure). Posterior fixation may include, but is not limited to, traditional pedicle screw fixation, facet screw fixation, interspinous plate or wiring fixation, intervertebral plates, intervertebral cages with vertebral or endplate fixation and/or the like. In some embodiments, the method comprises advancing a first bone screw through the passage, such that a distal end of the first bone screw extends at least partially into the intervertebral space. 
     According to some embodiments, a vertebral fusion system for fusing a first vertebra to a second vertebra comprises a first bone screw positioned through the first vertebra along a transpedicular passage of said first vertebra, wherein the first bone screw extends from a posterior end of a pedicle of the first vertebra through a superior endplate of the first vertebra, such that the passage extends into an intervertebral space located generally between the first and second vertebrae, a facet implant positioned in a facet joint between the first and second vertebrae and a connector coupling the first bone screw to the facet implant to at least partially stabilize the first vertebra relative to the second vertebra. According to some embodiments, the system further comprises a second bone screw positioned through the second vertebra. In some embodiments, the system comprises a rod or other connector connecting the first bone screw to the second bone screw. In some embodiments, the system comprises at least one implant configured to be positioned between adjacent endplates of the first and second vertebrae. In one embodiment, the implant comprises an expandable implant (e.g., a coiled implant, an inflatable implant, etc.). 
     According to some embodiments, a vertebral fusion system for fusing a first vertebra to a second vertebra comprises traditionally placed posterior pedicle screws (e.g., open, mini-open, or percutaneous) in the first vertebra and second vertebra with a connector coupling the first bone screw to the second bone screw, or a first bone screw positioned through the first vertebra along a transpedicular passage of said first vertebra, wherein the first bone screw extends from a posterior end of a pedicle of the first vertebra through a superior endplate of the first vertebra, such that the passage extends into an intervertebral space located generally between the first and second vertebrae, a facet implant positioned in a facet joint between the first and second vertebrae and a connector coupling the first bone screw to the facet implant to at least partially stabilize the first vertebra relative to the second vertebra. According to some embodiments, the system further comprises a second bone screw positioned through the second vertebra. In some embodiments, the system comprises a rod or other connector connecting the first bone screw to the second bone screw. In some embodiments, the system comprises at least one implant configured to be positioned between adjacent endplates of the first and second vertebrae. In one embodiment, the implant comprises an expandable implant (e.g., a coiled implant, an inflatable implant, etc.). 
     According to some embodiments, the passage created through the first vertebra is generally linear. In some embodiments, the method is performed percutaneously, minimally invasively, or in an open fashion. In some embodiments, the method is performed with use of x-ray, fluoroscopy or CT image guidance, fluoroscopy or CT navigation, robotically and/or using any other image-assistance and/or mechanical-assistance technologies. In some embodiments, the implant comprises an expandable implant (e.g., a coiled implant, an inflatable implant, a mechanically expandable implant, a fillable implant, etc.). According to some embodiments, removing native material comprises removing disc material, material from an endplate of the first vertebra and/or the second vertebra and/or the like. In some embodiments, the tissue removal tools comprise a malleable tool, deployable ring curette, ribbon or wire, a curette, a brush, a movable ribbon and/or the like. In some embodiments, the discectomy tools may be introduced in a linear fashion (or a substantially linear) through a bony channel or cannula. In some embodiments, the tools can be reconfigured or otherwise changed to an angled, curved and/or other non-linear configuration once entered into the targeted disc or intervertebral space. In some embodiments, the tool(s) may be moved, rotated and/or otherwise changed (e.g., in terms of position, shape and/or other configurations). In some embodiments, such change can be accomplished, at least in part, using manual and/or mechanically-assist tools. For instance, in one embodiment, manipulation of the tool(s) can be performed through control or movement of a proximal handle/introducer. In some embodiments, the tool(s) can at least partially cut/remove disc material, endplate cartilage, infection within the disc, or other materials/tissue within the intervertebral spaces or from the vertebra themselves. In some embodiments, the tissue removal tool comprises linearly aligned instruments that that can be introduced through a linear bony channel or a linear cannula, once introduced into the intervertebral (or vertebral) space may have an angleable, curveable, shapeable or an expandable head portion, wherein the head portion is configured to assume a collapsed positioned during advancement through the passage and wherein the head portion is configured to selectively assume angleable, curveable, shapeable or an expanded position within the intervertebral space. 
     According to some embodiments, the method additionally comprises inserting a guidewire into the passage, wherein tools, devices and/or other materials are guided through the passage using the guidewire. In some embodiments, the method further comprises inserting an access device within the passage to facilitate the movement of tools or devices through the passage. In one embodiment, the method further comprises inserting a second bone screw through the second vertebra. In some embodiments, the method comprises inserting a first bone screw through the first vertebra and second bone screw through the second vertebra. In some embodiments, the method additionally comprises connecting the first bone screw to the second bone screw (e.g., using a rod or other connector). In some embodiments, the first bone screw and the second bone screw do not extend through an endplate of the first or second vertebrae. 
     According to some embodiments, the method further comprises inserting a facet implant in at least one of the facet joints between the first and second vertebrae to fuse the first and second vertebrae at the at least one of the facet joints. In some embodiments, the facet implant is configured to selectively distract adjacent surfaces of the first and second vertebrae. In some embodiments, the facet implant comprises one or more teeth and/or other ratcheting members to facilitate the distraction of the vertebrae. In some embodiments, the method further comprises removing at least some native tissue within the facet joint before inserting the facet implant in said facet joint. In some embodiments, removing at least some native tissue within the facet joint comprises selectively moving a rasping device within said joint. In some embodiments, the method further comprises securing the first bone screw to the facet implant. 
     According to some embodiments, a method of fusing a first vertebra to a second vertebra comprises creating a passage from a posterior end of a pedicle of the first vertebra through a superior endplate of the first vertebra, such that the passage extends into an intervertebral space located generally between the first and second vertebrae, removing native tissue located within the intervertebral space by advancing a tissue removal tool through the passage and selectively moving said tissue removal tool within the intervertebral space, advancing a first bone screw through the passage, such that a distal end of the first bone screw extends at least partially into the intervertebral space, inserting a second bone screw through the second vertebra and attaching the first bone screw to the second bone screw. 
     According to some embodiments, a method of fusing a first vertebra to a second vertebra comprises creating a passage from a posterior end of a pedicle of the first vertebra through a superior endplate of the first vertebra, such that the passage extends into an intervertebral space located generally between the first and second vertebrae, removing native tissue located within the intervertebral space by advancing a tissue removal tool through the passage and selectively moving said tissue removal tool within the intervertebral space, advancing a first bone screw through the passage, such that a distal end of the first bone screw extends at least partially into the intervertebral space and inserting a facet implant in at least one of the facet joints between the first and second vertebrae to fuse the first and second vertebrae at the at least one of the facet joints. 
     According to some embodiments, a method of accessing an intervertebral space of a patient&#39;s spine in a minimally invasive manner comprises creating a passage from a posterior end of a pedicle of a vertebral member using a probe, advancing the probe through the pedicle and to a main body portion of the vertebral member, advancing the probe through a superior endplate of the vertebral member and into the intervertebral space and enlarging the passage using at least one tap to create an enlarged passage from a posterior of the pedicle to the intervertebral space. In some embodiments, the enlarged passage traverses at least three cortical layers of the vertebral member. 
     According to some embodiments, the method additionally comprises positioning a cannulated access device within the enlarged passage. In one embodiment, the cannulated access device comprises a plurality of external threads. In some arrangements, the method further comprises providing at least one tool through the enlarged passage and moving said at least one tool within said enlarged passage in order to remove native disc material adjacent the target intervertebral space. In some embodiments, the at least one tool comprises a brush, an abrasive member or surface and/or any other device. 
     According to some embodiments, the method further comprises creating a second passage from a posterior end of a second pedicle of the vertebral member using a probe, advancing the probe through the second pedicle and to a main body portion of the vertebral member, advancing the probe through a superior endplate of the vertebral member and into the intervertebral space and enlarging the second passage using at least one tap to create a second enlarged passage from a posterior of the second pedicle to the intervertebral space. In one embodiment, the second enlarged passage traverses at least three cortical layers of the vertebral member. 
     According to some embodiments, the method further comprises passing at least one tool through the passage and the second passage in order to remove native disc and/or other tissue of the patient. In some embodiments, the at least one tool is passed over a guidewire or cable, wherein the guidewire or cable is positioned through the passage and the second passage. In one embodiment, the method further includes delivering an expandable implant into the intervertebral space through at least one of the passage and the second passage. In one embodiment, the method additionally comprises delivering a structural implant into the intervertebral space through at least one of the passage and the second passage. 
     According to some embodiments, the method further includes delivering a disc replacement device into the intervertebral space through at least one of the passage and the second passage. In one embodiment, the method further comprises delivering a medicine injection device (e.g., an infusion pump, another device, etc.) into the intervertebral space through at least one of the passage and the second passage. In some embodiments, the method further comprises delivering a disc sampling device and/or other biopsy device into the intervertebral space through at least one of the passage and the second passage. In some embodiments, removed native tissue is removed through at least one of the passage or the second passage for subsequent biopsy or other analysis. In one embodiment, the method further comprises accessing a disc located within the intervertebral space for nucleus replacement, other non-fusion procedures and/or any other purpose. 
     According to some embodiments, the method further includes delivering at least one expandable implant within the intervertebral space. In some embodiments, the method additionally comprises expanding the at least one expandable implant once said at least one expandable implant is delivered to the intervertebral space. In one embodiment, the method further includes delivering at least one material to the intervertebral space. In some embodiments, the at least one material comprises a grafting material, putty or other filler material. In some embodiments, the method additionally comprises positioning a screw within the enlarged passage. In some embodiments, a screw may be advanced to at least partially (e.g., partially, completely, etc.) contact the inferior endplate of the second vertebra. In some embodiments, a screw may be placed through the posterior pedicle with the tip of the screw remaining, at least partially, within the vertebral body. In one embodiment, the screw may have an ingrowth surface (e.g., to encourage bone growth into the surface of the screw) and/or many use material(s) that encourage bone growth. In some embodiments, the screw may be advanced across the superior endplate, e.g., into the intervertebral space, to push the second vertebra inferior endplate into a more lordotic position relative to the first vertebra. 
     According to some embodiments, a pedicle screw configured for placement within a target vertebral member of a patient comprises a head and a shaft portion, wherein at least a portion of the shaft portion is threaded, and wherein the pedicle screw is configured for placement from a posterior portion of a pedicle of the vertebral member to and through a superior endplate of the vertebral member. Further the pedicle screw is configured to extend through at least three cortical surfaces of the vertebral member. According to some embodiments, the head is of a fixed angle, uniaxial or polyaxial type. In one embodiment, the shaft comprises a cortical thread pattern, a cancellous thread pattern and/or a combination thereof. 
     According to some embodiments, a method of accessing an intervertebral space of a patient&#39;s spine in a minimally invasive manner compromises creating a passage from a posterior end of a pedicle of a vertebral member using a probe, advancing the probe through the pedicle and to a main body portion of the vertebral member, advancing the probe through a superior endplate of the vertebral member and into the intervertebral space and enlarging the passage using at least one tap to create an enlarged passage from a posterior of the pedicle to the intervertebral space. In some embodiments, the enlarged passage traverses at least three cortical layers of the vertebral member. 
     In some embodiments, the method additionally includes positioning a cannulated access device within the enlarged passage. In one embodiment, the cannulated access device comprises a plurality of external threads. In some embodiments, the method further comprises delivering at least one expandable implant within the intervertebral space. In some embodiments, the method additionally includes expanding the at least one expandable implant once the at least one expandable implant is delivered to the intervertebral space. According to some embodiments, the method further comprises delivering at least one material to the intervertebral space. In one embodiment, the at least one material comprises a grafting material, putty or other filler material. In some embodiments, the method additionally includes positioning a screw within the enlarged passage. 
     According to some embodiments, a pedicle screw configured for placement within a target vertebral member of a patient comprises a head and a shaft portion, wherein at least a portion of said shaft portion is threaded. The pedicle screw is configured for placement from a posterior portion of a pedicle of the vertebral member to and through a superior endplate of the vertebral member. In some embodiments, the pedicle screw is configured to extend through at least three cortical surfaces of the vertebral member. In some embodiments, the head is of a fixed angle, uniaxial or polyaxial type. In several embodiments, the shaft comprises a cortical, cancellous and/or combination type thread pattern. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects and advantages of the present application are described with reference to drawings of certain embodiments, which are intended to illustrate, but not to limit, the present inventions. It is to be understood that these drawings are for the purpose of illustrating concepts of the present inventions and may not be to scale. 
         FIGS. 1A to 1D  illustrate various views of transpedicular openings through a vertebral member according to one embodiment; 
         FIGS. 2A to 2D  illustrate various views of the transpedicular openings of  FIGS. 1A-1D  having guidewires passed therethrough; 
         FIGS. 3A to 3D  illustrate various views of the transpedicular openings of  FIGS. 1A-1D  having taps or other opening enlargement devices positioned therein; 
         FIGS. 4A to 4D  illustrate various views of the transpedicular openings of  FIGS. 1A-1D  having cannulated access devices positioned therein; 
         FIGS. 5A to 5D  illustrate various views of one embodiment of a tissue removal system positioned within the cannulated access devices of  FIGS. 4A to 4D ; 
         FIGS. 6A to 6D  illustrate various views of another embodiment of a tissue removal system positioned within the cannulated access devices of  FIGS. 4A to 4D ; 
         FIGS. 7A and 7B  illustrate different side views of a blunt, cannulated rasping tool according to one embodiment; 
         FIG. 8A  illustrates a perspective view of one embodiment of a curette or other disc tissue removal member configured to pass through a cannulated access device or other opening and into an intervertebral space; 
         FIG. 8B  illustrates a perspective view of another embodiment of a tissue removal member; 
         FIG. 9A  illustrates a side view of one embodiment of a brush or other bristled device configured to remove disc material and/or other tissue from an intervertebral space; 
         FIG. 9B  illustrates a side view of the brush of  FIG. 9A  in a collapsed position; 
         FIG. 10A  illustrates a side view of one embodiment of a tissue removal device configured to remove disc material and/or other tissue from an intervertebral space; 
         FIG. 10B  illustrates a side view of the device of  FIG. 10A  in a collapsed position; 
         FIG. 11  illustrates a side view of one embodiment of a radially expandable device configured to remove disc material and/or other tissue from an intervertebral space; 
         FIG. 12A  illustrates a side view of one embodiment of a radially expandable device configured to remove disc material and/or other tissue from an intervertebral space; 
         FIG. 12B  illustrates a side view of the device of  FIG. 12A  in a collapsed position; 
         FIG. 13A  illustrates a side view of an expandable implant positioned within a target interbody space, according to one embodiment; 
         FIGS. 13B and 13C  illustrate side views of the implant of  FIG. 13A  in collapsed and expanded positions, respectively; 
         FIG. 14  illustrates a side view of an expandable implant positioned within a target interbody space according to another embodiment; 
         FIG. 15  illustrates a side view of an expandable implant positioned within a target interbody space according to yet another embodiment; 
         FIG. 16A  illustrates a side view of an expandable implant positioned within a target interbody space according to still another embodiment; 
         FIGS. 16B and 16C  illustrate the implant of  FIG. 16A  and the corresponding delivery device at various stages of expansion; 
         FIGS. 17A to 17D  illustrate various views of pedicle screws secured to a vertebral member through transpedicular openings according to one embodiment; 
         FIG. 18A  illustrates a side view of a facet joint implant having a ratcheting design according to one embodiment; 
         FIG. 18B  illustrates a top view of the facet joint implant of  FIG. 18A ; 
         FIGS. 19A to 19D  illustrate various views of a spinal fusion system according to one embodiment; 
         FIG. 20  illustrates a side or lateral view of a spinal fusion system according to another embodiment; 
         FIG. 21A  schematically illustrates one embodiment of a pedicle screw; 
         FIG. 21B  schematically illustrates another embodiment of a pedicle screw; 
         FIGS. 22A and 22B  illustrate different views of one embodiment of a transpedicular screw; 
         FIG. 23  illustrates a perspective view of one embodiment of a diskectomy tool; 
         FIGS. 24A and 24B  illustrate different perspective views of one embodiment of a diskectomy, pituitary-type tool; 
         FIG. 25  illustrates a side view of a spine stabilization system comprising a transpedicular screw coupled to a translaminar screw using a plate or other member according to one embodiment; 
         FIGS. 26A to 26F  illustrate different views of one embodiment of a plate or coupling for a stabilization system; 
         FIGS. 27A to 27C  illustrate various components of a system used to deliver one or more implants within a targeted intervertebral space according to one embodiment; 
         FIGS. 28 and 29  illustrate the system of  FIGS. 27A to 27C  being used to deliver an implant into a targeted intervertebral space; and 
         FIG. 30  illustrates an additional fixation system used to reinforce a fusion procedure. 
     
    
    
     DETAILED DESCRIPTION 
     A variety of examples described below illustrate various configurations that may be employed to achieve desired improvements. The particular embodiments and examples are only illustrative and not intended in any way to restrict the general inventions presented herein and the various aspects and features of such inventions. 
     According to some embodiments, the present application discloses various devices, systems and methods for accessing the intervertebral or interbody space of a patient&#39;s spine and/or performing certain procedures related to spinal fusion using minimally invasive surgery (MIS) techniques. As discussed in greater detail herein, the intervertebral or interbody space of the targeted portion of the patient&#39;s spine is accessed and/or treated minimally invasively using, at least in some embodiments, a “transpedicular” approach. The terms “intervertebral space” and “interbody space” are used interchangeably herein, and generally refer to the space, gap or region between adjacent vertebral members. By way of example, as illustrated in the various views of  FIGS. 1A-1D , the intervertebral space  20  between adjacent vertebrae  10 A,  10 B can be accessed using one or more openings or passages  16  created through one of the vertebrae (e.g., the lower of the two adjacent vertebrae in the depicted arrangement). In some embodiments, such openings or passages are created, accessed and/or otherwise use using MIS techniques or procedures. As shown in  FIGS. 1A-1D , in some embodiments, an opening  16  is initiated along or near a posterior portion of the vertebra or vertebral member  10 B and is advanced through the pedicle. The opening can include a generally upwardly orientation so that it extends through at least a portion of the body portion of the corresponding vertebra. In some embodiments, as illustrated in  FIGS. 1A-1D , the transpedicular opening  16  passes through the upper endplate  14 B of the vertebra  10 B. 
     As shown in  FIGS. 1A-1D , the transpedicular opening  16  can be generally straight or liner (e.g., along a single longitudinal line or path) from the posterior side of the pedicle to the upper endplate  14 B of the vertebral member  10 B. Accordingly, the need to create a non-linear (e.g., curved) pathway through the vertebra  10 B is eliminated. This can provide certain advantages to the surgeon performing a spinal fusion procedure. For example, as discussed in greater detail herein, the required instrumentation and tools used to create such a passage are relatively simple. Relatedly, the corresponding surgical procedures and techniques used by the surgeon are also relatively simple and straightforward due to the linear or substantially linear orientation of the passage or accessway into the target intervertebral space. 
     With continued reference to  FIGS. 1A-1D , a transpedicular passage or opening  16  can advantageously provide access to an intervertebral space  20  using MIS techniques and methods. This can provide certain benefits and advantages over existing approaches (e.g., open anterior approach, lateral approach, etc.). For example, the need to contact and move nerves and other sensitive organs, structures and other anatomical regions surrounding the spine is reduced or eliminated. As a result, a surgeon can obtain access to one or more interbody spaces through a relatively simple and safe posterior approach. In some embodiments, as discussed in greater detail herein, such minimally invasive approaches are further facilitated by the fact that access to the interbody space is provided using a linear or substantially linear passage through a portion of the vertebral member. In general, the overall collateral damage associated with the approaches disclosed herein is generally reduced when compared to open approaches. For example, the skin incision through which the MIS is performed is generally smaller than those used in other approaches (e.g., methods in which tissue retractors are used, open surgery, etc.). Further, the MIS approaches disclosed herein advantageously allow concurrent proximity/access to the facet joints, which can be simultaneously fused or distracted for indirect decompression of the neural foramen/lateral recesses. For example, as discussed in greater detail herein with reference to  FIGS. 18A-19D , a spinal fusion system can comprise, at least in part, one or more facet joint implants. Additionally, in some embodiments, this approach to the intervertebral/disc space does not require the compromising, incision, removal and/or any damage or harm to the disc annulus. The approach also allows for placement of a tricortical screw for enhanced fixation purposes. 
     According to some embodiments, a surgical procedure involves the creation of two transpedicular passages  16  in a targeted vertebra  10 B. For example, as shown in  FIGS. 1A-1D , a passage  16  can be made through each of the pedicles P. Thus, in some embodiments, the passages  16  are symmetrical or substantially symmetrical about the longitudinal axis of a patient&#39;s spine. As discussed in greater detail herein, creating two transpedicular openings  16  in a vertebra can enhance the ability of a surgeon to manipulate tools and/or other instruments within a target interbody space  20 , to selectively deliver devices (e.g., implants) and/or other materials (e.g., bone grafting materials) into and/or out of the interbody space and/or to perform other tasks related to the interbody space (e.g., to remove native disc material, to repair a disc, to biopsy or otherwise excise tissue, to prepare the vertebral endplates and/or other tissues in advance of fusion and/or the like). However, in other arrangements, only a single transpedicular opening  16  can be made to access a target intervertebral space. A spinal fusion system in accordance with the various embodiments described herein can comprise one, two, three or more transpedicular openings  16 , as desired or required. 
     As illustrated in the various views of  FIGS. 2A-2D , one or more transpedicular openings or passages  16  can be configured to receive a guidewire G. In some embodiments, one or more instruments, tools, devices and/or other items may be delivered to and/or from the intervertebral space over the guidewire G, as desired or required, thereby facilitating a particular surgical procedure. The size, length, materials of construction, flexibility and/or other characteristics of the guidewire G can vary, depending on the particular application or use. For example, in some arrangements, the gauge of the guidewire G is between 16 and 22 (e.g., 16, 18, 20, 22), and the guidewire G comprises stainless steel, titanium, vitallium and/or any other metal, alloy or other material. In other embodiments, however, the gauge of the guidewire can be smaller than 16 (e.g., 14, 12, 10, smaller than 10, etc.) or greater than 22 (e.g., 24, 26, 28, 30, greater than 30, etc.), as desired or required for a particular application or procedure. 
     The distal end of the guidewire G can be removably anchored within a portion of the anatomy to help ensure that instruments, tools and/or other devices are safely and properly delivered to and/or from the target intervertebral space  20 . For example, in certain embodiments, as illustrated in  FIGS. 2B and 2C , the guidewire G can be anchored within a portion of the patient&#39;s anatomy (e.g., in or near the inferior endplate  15 A of the adjacent vertebra  10 A). 
     As discussed in greater detail herein, implants, instruments, tools and/or other devices can be passed to and/or from a target intervertebral space  20  minimally invasively with the assistance of the guidewire G and/or imaging technologies (e.g., fluoroscopy). Alternatively, such devices, tools and/or other items can be moved through a transpedicular opening  16  without the use of a guidewire G. The use of a guidewire G can assist in the accurate delivery of tools, implants and/or other devices through the passage, especially in a minimally invasive procedure. One embodiment of how a transpedicular passage  16  is created within a patient&#39;s vertebral member is described below. 
     According to some embodiments, in order to begin the surgical procedure, a surgeon makes bilateral, posterior incisions in the skin and fascia of a patient. Alternatively, when only a single passage or accessway  16  is to be created to the target intervertebral space through the vertebra, the surgeon can make only a single incision. In still other embodiments, more than two (e.g., three, four, more than four, etc.) passages can be created within a single vertebral member. Regardless of the number of passages, corresponding incisions through the skin and related tissue can be generally small (e.g., short in length) and can be located immediately distal and lateral to the pedicle P (e.g., at or near the junction of the pars interarticularis and the transverse process). Next, a probe (e.g., trochar, other sharp-tipped probe, etc.) can be used to perform a blunt dissection through the patient&#39;s muscular layer adjacent an incision. According to some embodiments, such a dissection roughly approximates the avascular plane of the Wiltse approach. 
     According to some embodiments, the probe is then tamped into one of the pedicles P of the vertebra. For example, the trochar or other instrument can be placed at the “6 o&#39;clock” position of the pedicle and tamped into the pedicle cortex with a trajectory that is generally directed toward the “12 o&#39;clock” position (as illustrated in  FIG. 1A ). Such a trajectory can advantageously permit the probe to exit the endplate  14 B of the vertebra  10 B at or near the junction of the posterior one-third and the middle one-third of the endplate in lateral view. As illustrated herein, the path created by the probe (and thus, the path of the corresponding passage or accessway through the vertebra) is generally linear or straight. In other words, the longitudinal axis of the passage falls along a single line. As noted above, such a linear approach can simplify the procedure of creating the passage. Further, the approach can advantageously permit a surgeon to use simpler tools and instrumentation in order to perform the procedure. For example, the need for drills or other passage-creating devices or systems that are configured to turn, rotate or otherwise change direction within the vertebral member are eliminated. In any of the procedures disclosed herein, fluoroscopy and/or other imaging technologies can be used to ensure that the probe (e.g., trochar) or other instrument is accurately positioned and advanced relative to the pedicle, endplate and other portions of the patient&#39;s spine. 
     Advancement of the probe through the top endplate  14 B of the vertebra  10 B can advantageously create a pathway from the posterior side of the pedicle P to the intervertebral space  20  located above the targeted vertebra  10 B. Thus, access to the space  20  can be created using a MIS approach without the need for open surgery, tissue retractors, dilators and/or other more intrusive devices, systems and methods. According to certain arrangements, the trochar or other sharp-tipped probe or instrument is cannulated. Thus, a guidewire G ( FIGS. 2A-2D ) can be advanced within the lumen or other opening of the instrument after the probe has been advanced to the target intervertebral or interbody space  20 . As discussed above with reference to  FIGS. 2B and 2C , the guidewire G can be anchored into or otherwise fixed to (e.g., temporarily, removably, etc.) the adjacent inferior endplate  15 A of the cephalad vertebra  10 A or any other portion of the patient&#39;s spine. 
     In some embodiments, as illustrated in  FIGS. 3A-3D , after a transpedicular passage has been created using a trochar (or using any other probe or instrument), one or more taps  40  are used to progressively enlarge the passage. For example, a plurality (e.g., two, three, more than three, etc.) of incrementally larger taps or similar devices  40  can be sequentially placed within the passage  16  to increase the diameter or other cross-dimensional size of the passage. Such taps  40  can help ensure that the passage  16  is enlarged to a desired size in a safe and predictable manner (e.g., without threatening or otherwise undermining the structural integrity of the vertebra being penetrated). According to some embodiments, the taps or other enlargement devices  40  are cannulated, thereby allowing them to be moved over a guidewire G (e.g.,  FIGS. 2A-2D ). The taps can vary in size, depending on the patient&#39;s age, size, spinal condition, general physical condition and other characteristics of the spine being treated. Further, the quantity of taps needed and their incremental size (e.g., diameter) can vary depending on the procedure to be performed, the implants, tools, instruments and/or other devices or materials that will be delivered through the passage (e.g., to or from the target interbody space) and/or any other factors or considerations. By way of example, in some embodiments, the outside diameters of the taps  40  vary between about 4 mm and 10 mm. 
     According to some embodiments, after the widest (e.g., largest diameter) tap  40  has been removed from the vertebra  10 B, as shown in  FIGS. 4A-4D , a cannulated access device  50  can be positioned within the passage  16  created by the probe (e.g., trochar) and/or the taps  40 . Such a cannulated access device  50  can extend completely, substantially completely or only partially along the length of a transpedicular passage  16  created within a target vertebra. The cannulated access device  50  can include external threads or other engagement features that assist in anchoring (e.g., removably or permanently) within the vertebra. For example, in embodiments of the access device  50  that comprise external threads, the device  50  can be advanced into (and/or removed from) the passage  16  by rotation (e.g., like a screw). In other arrangements, the cannulated access device  50  comprises one or more other types of engagement features, such as, for example, teeth, prongs, recesses and/or the like, either in lieu of or in addition to threads. Alternatively, access device  50  can include a roughened surface and/or any other feature that helps secure it within the passage  16 . In yet other embodiments, the cannulated access device  50  does not comprise any external threads or other engagement features at all. As noted above with reference to creating a passage through the vertebral member, in some embodiments, the access device  50  is positioned using minimally invasive methods. The access device  50  can be permanent or temporary, as desired or required by a particular application or procedure. In some embodiments, once a passage  16  has been created within the vertebra, various tools, devices and/or other members are selectively moved through (e.g., in or out) of the passage without the need for an access device. 
     Regardless of the exact external characteristics of the access device  50 , in order to help ensure that the access device remains securely affixed within the passage  16  during subsequent procedures (e.g., delivery of various devices, instruments, tools, materials, etc.), one or more external portions of the access device  50  can form a generally tight fit with the adjacent internal surface of the passage  16 . For example, as noted above, some arrangements of a cannulated access device can include threads and/or other engagement features along their exterior surface. Alternatively, a tight tolerance between the outside of the access device  50  and the internal surface of the passage  16  can be used to provide a friction-fit connection. In other arrangements, adhesives, such as glues, bone cement and/or other materials, can be used to help secure the cannulated access device  50  within a transpedicular passage  16 . 
     With continued reference to  FIGS. 4A-4D , according to some embodiments, the proximal end of an access device  50  extends proximally of the passageway  16  and the patient&#39;s pedicle P. Thus, a surgeon can easily insert and/or remove implants, instruments, tools and/or other devices to and/or from the transpedicular passageway(s)  16 , as desired or required by a particular procedure or protocol. In other words, the cannulated access device can extend rearwardly from the posterior end of the spine to facilitate a surgeon&#39;s access to passages  16 . Alternatively, the access device  50  can be generally flush or recessed relative to the posterior end of the transpedicular passage  16 . 
     The inner diameter or other cross-sectional dimension of the cannulated access device  50  can vary depending on the patient&#39;s anatomy, the size of the targeted pedicles P, the condition of the patient&#39;s spine and/or one or more other factors or considerations. Accordingly, the access device  50  can be provided in a plurality of standard or non-standard sizes, shapes and/or other configurations. 
     Once the transpedicular pathway or passage  16  within the vertebra has been created and the pathway has been adequately enlarged and protected (e.g., using taps, cannulated devices, access devices and/or other methods or devices, such as those discussed herein, etc.), the guidewire G can be removed, leaving the lumen of the cannulated access device  50  or simply the passage  16  (e.g., in arrangements where no access device is used) generally free of any obstructions. In some embodiments, the guidewire G is removed only after a cannulated access device  50  has been properly seated within the targeted vertebra (e.g., up to the endplate cortex of the vertebra). As a result, one or more procedures can be subsequently performed. For instance, as discussed in greater detail herein, the passage  16  can be used to remove anatomical tissue, fluids or other materials (e.g., for biopsy, testing, other excision procedures, etc.), to remove native disc material (e.g., discectomy), for endplate preparation, to deliver implants, bone grafting agents, other fillers and/or other devices or materials, for interbody structural graft placement, interbody distraction and/or for any other purpose. Further, as discussed in greater detail herein, the passage  16  can be used to deliver and secure an appropriately sized fastener (e.g., standard or non-standard pedicle screw, other fastener, etc.) to the corresponding vertebra. In some embodiments, such a fastener can comprise a spinal fusion system together with one or more other fasteners (e.g., pedicle screws in adjacent vertebra(e), rods, other connectors, etc.), implants (e.g., facet joint implants) and/or the like. 
     As noted above, a direct pathway into the adjacent interbody or intervertebral space  20  can be created through one or both of the pedicles of a vertebra  10 A,  10 B. In some embodiments, it is advantageous to provide transpedicular access to the interbody space  20  via both pedicles in order to enhance the maneuverability of implants, tools, instruments and/or other devices therein. In arrangements involving relatively simple procedures (e.g., biopsy, delivery of a medicament, etc.), it may be desirable to provide only a single transpedicular pathway to the interbody space  20 . Additional details regarding various procedures that could be performed using one or more transpedicular passages are provided below. 
     Removal of Interbody Tissue 
       FIGS. 5A-5D  illustrate different views of one embodiment of a system  100  configured to at least partially remove native disc material and/or other tissue located within an intervertebral space  20  of a patient. This can be performed as part of a discectomy, a biopsy, a preliminary step in advance of subsequent procedures or steps and/or the like. As shown, a tissue removal system  100  can include one or more cutting members  110 , abrasive members  120 , curettes and/or any other device configured to selectively excise, grasp and/or remove tissue. Such tools, instruments and/or other devices can be placed into one or more transpedicular passages  19  of a vertebra  10 A,  10 B, as desired or required. Thus, the tools, instruments and/or other devices can be advantageously sized, shaped and/or otherwise configured to pass through the passage using minimally invasive techniques (e.g., MIS). As discussed in greater detail herein, such tools and/or other devices can be expandable and/or collapsible to facilitate delivery through the passage. In any of the embodiments disclosed herein, a visualization scope or other imaging member can be inserted within or near the interbody space  20  being treated (e.g., via the transpedicular passages  19 , other openings, etc.) to advantageously provide a surgeon with visual confirmation of the procedure being performed. In other arrangements, external imaging tools, such as, for example, fluoroscopy, other x-ray-based technologies and/or the like, can be used to assist the surgeon performing a procedure within or near the interbody space  20  (e.g., vertebral body distraction, fusion, discectomy, screw or other fastener insertion, etc.). 
     With continued reference to  FIGS. 5A-5D , a cutting member  110 , an abrasive member  120  and/or any other component of a tissue removal system  100  can include a proximal portion that is grasped and manipulated by the surgeon. According to some embodiments, the removal system  100  comprises one or more actuators and/or other controls that allow the surgeon to operate one or more features of the system, such as, for example, movable blades or other cutting members, movable abrasive members (e.g., rotating or reciprocating abrading head) and/or the like. In the arrangement depicted in  FIGS. 5A-5D , the cutting member  110  comprises scissor-like blades or other sharp surfaces that rotate or otherwise move relative to each other. Thus, a surgeon can actuate the cutting member  110  to excise target native disc and/or other tissue within or near the interbody area  20 . Similarly, the abrading member  120  can be used to target and remove disc material and/or other tissue within or adjacent the interbody space. Any other type of cutting and/or abrading member can be used, either in lieu of or in addition to those illustrated or discussed herein. For example, other mechanical devices (e.g., brushes, expandable members having sharp edges or features, etc.), laser technology, heat and/or other ablative-based systems can be used to remove, ablate, destroy, alter and/or otherwise affect tissue located within or near a target interbody space  20 . 
     According to some embodiments, one or more removal members can be routed through a transpedicular passage  16  to capture and/or help move excised disc material, other tissue, fluids and/or other debris or materials out of the interbody space  20 . For example, the removal member can include a vacuum or suction line (e.g., in fluid communication with a vacuum source), a grasping device and/or the like. In other arrangements, such as those used in biopsy procedures, a removal member can be configured to obtain a tissue sample, separate it from adjacent tissue and grasp it for removal from the spine. 
     In other embodiments, a tissue removal system comprises an abrading member or other device that is adapted to roughen or otherwise undermine at least a portion of an endplate in preparation for a fusion implant. The roughening of the endplate (e.g., which may include causing at least a portion of the endplate to bleed) can promote and facilitate attachment of an implant and/or grafting material to the adjacent vertebral surfaces, thereby increasing the likelihood of success of a spinal fusion procedure. 
     As illustrated in  FIGS. 6A-6D , in one embodiment, a tissue removal or roughening system  200  comprises two or more components  210 ,  220  that can be selectively connected to each other within the interbody space  20 . For example, the system  200  can include a grasped portion  210  and a corresponding retention portion  220 , each of which is advanced to the target intervertebral space  20  through separate passages or openings  16 . In one embodiment, the portions  210 ,  220  can be releasably connected within the interbody space  20  (e.g., with the assistance of fluoroscopy, other imaging technology or tool, etc.). Once attached to each other, the different portions  210 ,  220  of the removal or roughening system  200  can be moved as a unitary structure by manipulating the proximal ends of each separate component  210 ,  220 . For example, the proximal ends of the components  210 ,  220  can be directed in forward and rear directions within each of the passages  16  (e.g., including respective access devices  50  situated therein, if any) to move the attached distal ends of the components in a reciprocating manner within one or more regions of the interbody space  20 . Thus, if the distal ends of the separate components  210 ,  220  comprise cutting or abrading members and/or features, native disc material, chondral or bone portion of vertebral endplates and/or other tissue within the interbody space  20  can be excised, roughened, shaved and/or otherwise undermined, in accordance with a desired procedure or method. In addition, a thin, flexible cable may be passed through one passage (e.g., within one access device) into the disc space and grasped and pulled back into the opposite passage (e.g., within the other access device). Then various flexible cannulated disc removal and abrading tools may be passed over such a cable system as part of the discectomy and/or disc space preparation procedure. The flexible, cannulated tools can comprise wire brushes, other types of brushes (e.g., brushes having different materials and/or components), expandable balloons with or without roughened working surfaces and/or other varieties of tools or instruments, as desired or required for a particular application or use. 
       FIGS. 7A and 7B  illustrate different side views of one embodiment of a rasped surface probe or tool  800  configured for placement through a transpedicular passage of a vertebral member. The tool  800  can be cannulated or non-cannulated, as desired or required for a particular application or use. As discussed in greater detail below, such a probe or tool can also be used to treat a facet joint and/or any other portion of the spine as part of a spinal fusion system. As shown, the rasping tool or probe  800  can include a handle  810  along its proximal end. An elongated shaft  820  can extend from the handle  810  toward the distal end of the probe  800 . In some embodiments, as depicted in  FIGS. 7A and 7B , the distal end of the probe  800  comprises a rasping or abrading head  830  that is adapted to selectively remove disc material, cartilage, bone and/or other native tissue from the target interbody space and/or adjacent anatomical surfaces or portions. The head  830  can include one or more abrading structures or features  834 . For example, in some embodiments, the abrading structures  834  include a plurality of protruding members that generally extend radially outwardly (e.g., directly outwardly, at any angle relative to the longitudinal axis of the tool  800 , etc.). In other embodiments, other types of abrading structures or features (e.g., recesses, sharp edges, etc.) are used, either in lieu of or in addition to those illustrated in  FIGS. 7A and 7B . 
       FIG. 8A  illustrates one embodiment of a curette or other cutting tool  1500  that is sized, shaped and/or otherwise configured to be selectively delivered through a passage of a vertebral member. As noted above, such tools can be used to remove disc material from the target intervertebral space, to abrade and/or remove at a portion of the inferior and/or superior endplates adjoining the space and/or remove any other native tissue, as desired or required. 
     With continued reference to  FIG. 8A , the tool  1500  can comprise a handle portion  1512  and a main shaft or elongate portion  1510  extending distally therefrom. As shown, a distal end of the shaft  1510  can comprise a cutting head  1520 . In some embodiments, the head  1520  comprises a concave or other cup-shaped portion. The edges  1522  that form the concave head can be generally sharp in order to facilitate the removal of native tissue from a targeted portion of the interbody space. In other embodiments, the edge  1522  can be serrated and/or comprise one or more cutting features or members. The curette or cutting tool  1500  can be configured to fit within a passage (e.g., cannulated access device) of the vertebra being treated. Thus, the tool  1500  can be advantageously used as part of an overall minimally invasive approach. 
       FIG. 8B  illustrates another configuration of a curette of cutting tool  1500 ′ that is similar to the tool of  FIG. 8A . As shown, the depicted embodiment comprises a different head design  1520 ′. Specifically, the head  1520 ′ comprises an open middle portion. In other words, the head  1520 ′ of the tool  1500 ′ does not include a closed cup portion. In other embodiments, a different head design can be used for such a tool to accommodate a specific cutting and/or tissue-removal goal, as desired or required. For example, in one embodiment, the tool can include two or more head portions along or near the distal end. 
     As noted above, a brush or other bristled device can be delivered through the passage of the vertebra and manipulated within the target interbody space to abrade and remove tissue (e.g., native disc, endplate material, etc.). One embodiment of such a brush  1600  is illustrated in  FIGS. 9A and 9B . According to some embodiments, the brush  1600  is at least partially collapsible (e.g., radially) to facilitate delivery through a passage created within the vertebra using a minimally invasive approach.  FIG. 9A  illustrates a side view of the brush or bristled device  1600  in a radially expanded position. The brush  1600  can comprise a proximal elongate portion or shaft  1610  and a distal bristled portion  1620 A comprising a plurality of rigid, semi-rigid and/or flexible bristles. Any combination of bristles can be used to provide the desired rigidity, flexibility, strength, durability, abrasiveness and/or other properties to the brush. The bristles can comprise one or more metals, alloys, plastics or other polymers and/or any other suitable materials. In some embodiments, at least some of the bristles comprise nickel titanium (e.g., Nitinol) and/or other shape memory materials. 
       FIG. 9B  illustrates the brush  1600  in a radially collapsed or contracted orientation. In some embodiments, the brush is configured to be moved into such a lower profile orientation in order to facilitate its delivery through the passage of the vertebral member. Thus, the brush can be passed into or out of the target intervertebral space of the patient while in this radially collapsed position and expanded once its distal portion (e.g., the bristled head) has been properly positioned within the interbody space. According to some embodiments, the bristled portion  1620 B is maintained in a radially collapsed position using an outer sheath or other sleeve (not shown) that can be slidably moved relative to the bristles. In other embodiments, the bristles are adapted to be selectively moved between radially collapsed and expanded positions mechanically (e.g., by manipulating an actuator that is coupled to the bristled portion) and/or by any other method or device. 
     Regardless of its exact design and other features, the brush  1600 , once properly positioned within the targeted intervertebral space, can be manipulated by the surgeon in order to capture, abrade and/or otherwise remove disc material, endplate surfaces and/or other native tissue of the patient. In some embodiments, the shaft or elongate portion  1610  of the brush  1600  is at least partially flexible or steerable to permit the surgeon to rotate or otherwise move the bristled portion to specific portions of the intervertebral space. 
     Another embodiment of a tissue abrading and/or removal device  1700  is illustrated in  FIGS. 10A and 10B . As shown, the device  1700  comprises a proximal shaft or elongate portion  1710  and a distal head  1720 . In some embodiments, the head portion  1720  is configured to be selectively moved between a collapsed position ( FIG. 10B ) and an expanded position ( FIG. 10A ). As discussed herein in reference to other embodiments of such tissue removal or preparation tools, the head  1720  can be maintained in the radially collapsed or contracted orientation while the device  1700  is moved within or out of the passage of the vertebral member during a minimally invasive procedure. The head can move between its radially collapsed and expanded positions using a sheath, sleeve or other outer member. In other embodiments, the head can be collapsed and/or expanded using a mechanical actuator and/or any other device or method, as desired or required. 
     With continued reference to  FIG. 10A , when the device  1700  is expanded, the individual members  1722  that comprise the head  1720  can assume any one of a number of radial positions. Any combination of members  1722  can be used to provide the desired rigidity, flexibility, strength, durability, abrasiveness and/or other properties to the device  1700 . The members  1722  can comprise one or more metals, alloys, plastics or other polymers and/or any other suitable materials. In some embodiments, at least some of the members comprise nickel titanium (e.g., Nitinol) and/or other shape memory materials. Such a configuration of an expandable head  1720  can be particularly effective in capturing and removing native disc material from the targeted intervertebral space. In some embodiments, the expandable members  1722  of the head  1720  comprise relatively sharp edges and/or end portions to enhance the tissue capturing characteristics of the device. The members can also include one or more other tissue capturing features, such as, for example, nodes, barbs and/or the like, to further enhance the effectiveness of the device. 
     Another embodiment of a tissue cutting or abrading device  1800  that is well-suited for use in a minimally invasive approach is illustrated in  FIG. 11 . As shown, the device  1800  comprises a handle portion  1830  along its proximal end. A shaft or elongate portion  1810  that extends from the handle  1830  terminates in a cutting head along the distal end of the device. In some embodiments, the distal end of the shaft  1810  comprises a window or opening  1816  that provides access to a lumen, opening or other interior portion of the device. Thus, a flexible ribbon or member  1820  that is routed within such an inner lumen or opening of the device can be selectively urged out of the window  1816 , in a direction away from the shaft  1810 . For clarity,  FIG. 11  illustrates the ribbon or other member  1820  both in its collapsed orientation  1820 B and in its expanded orientation  1820 A (in phantom). In some embodiments, the flexible ribbon or other member  1820  comprises one or more metals, polymeric materials and/or any other suitable material. In some embodiments, the ribbon or other member  1820  comprises sharp edges and/or other tissue abrading features or portions (e.g., barbs, ridges, cutting members, rasped portions, etc.) to facilitate removal of native tissues. 
     With continued reference to  FIG. 11 , the device  1800  can comprise a movable lever or other actuator  1840  along its proximal end (e.g., near the handle  1830 ). In some embodiments, the actuator  1840  is coupled (e.g., mechanically) to the ribbon or other movable member  1820 , such that manipulation of the actuator  1840  (e.g., proximally and distally, rotatably, etc.) moves the ribbon or other movable member  1820  between the collapsed and contracted positions. Accordingly, as with other cutting, abrading, removal and/or preparatory tools disclosed herein, the device  1800  can be delivered through a passage created within a vertebral member (e.g., a transpedicular passage) and into a targeted intervertebral space. In order to enable or facilitate delivery of the device  1800  through the corresponding passage of the vertebra, the device can be in the collapsed position (e.g., the ribbon or other flexible member  1820 B is positioned within an interior of the shaft  1810 ). Once the distal portion of the device has been properly advanced within the targeted interbody space, the surgeon can manipulate the device so as to move the ribbon  1820  to the expanded position  1820 A. Accordingly, the surgeon can rotate or otherwise manipulate the expanded device in order to cut, shave and/or otherwise excise disc material, endplate surfaces and/or other native tissue of the patient. 
     Another embodiment of a tissue cutting and abrading tool  1900  is illustrated in  FIGS. 12A and 12B . The device  1900  is similar to the one depicted in  FIG. 11  and discussed above. For example, the device  1900  comprises a handle portion  1930  and a shaft or elongate portion  1910  extending distally therefrom. Further, the distal end of the elongate portion  1910  comprises one or more windows or openings  1916  through which one or more ribbons or other flexible members  1922 A can pass. In some embodiments, as discussed herein with reference to the device of  FIG. 11 , the ribbons or other movable members are configured to be moved between a collapsed position  1922 B ( FIG. 12B ) and an expanded position  1922 A ( FIG. 12A ) by manipulating (e.g., moving longitudinally, rotating, etc.) an actuator  1940 . As shown, such an actuator  1940  can be positioned at or near the handle  1930  of the device. 
     In  FIG. 12B , the device or tool  1900  comprises a total of two ribbons or other movable members  1922 B that can be expanded outwardly through corresponding windows or openings  1916  of the elongate portion  1910 . However, in other embodiments, the tool comprises fewer (e.g., one, as illustrated in  FIG. 11 ) or more (e.g., three, four, five, more than five, etc.) ribbons or other movable members  1922 , as desired or required by a particular application or use. Accordingly, as with other cutting, abrading, removal and/or preparatory tools disclosed herein, the device  1900  can be delivered through a passage created within a vertebral member (e.g., a transpedicular passage) and into a targeted intervertebral space. In order to enable or facilitate delivery of the device  1900  through the corresponding passage of the vertebra, the device can be in the collapsed position (e.g., the ribbons or other flexible members  1922  are positioned within an interior of the shaft  1910 ). Once the distal portion of the device has been properly advanced within the targeted interbody space, the surgeon can manipulate the device so as to move the ribbons and/or other flexible or movable members to the expanded position  1922 A. Accordingly, the surgeon can rotate or otherwise manipulate the expanded device in order to cut, shave and/or otherwise excise disc material, endplate surfaces and/or other native tissue of the patient. 
     The shape, size (e.g., width, thickness, etc.), materials and/or other characteristics of the ribbons or other movable members disclosed herein (e.g., with reference to  FIGS. 11, 12A and 12B ) can be selected to provide the desired rigidity, flexibility, strength, durability, sharpness, cutting ability, abrasiveness and/or other properties to the tool. The ribbons can comprise one or more metals, alloys, plastics or other polymers and/or any other suitable materials. In some embodiments, at least some of the ribbons comprise nickel titanium (e.g., Nitinol) and/or other shape memory materials. 
     According to some embodiments, the transpedicular passage(s)  16  formed within a vertebra  10 A,  10 B can be used to deliver one or more materials to a targeted interbody space  20 . For example, grafting agents, other bone forming materials, other filler materials and/or other substances or devices can be transferred to the intervertebral space  20  through one or more tubes or other conduits removably positioned within the passage  16  and/or the cannulated access device  50 . The delivery of such devices can be advantageously performed using one or more minimally invasive approaches. 
     Interbody or Intervertebral Implants 
     As noted above, one or more implants can be selectively delivered to a target intervertebral or interbody space  20  via a transpedicular passage  16 . According to some embodiments, such implants promote fusion of the two adjacent vertebral members. Such implants can also be used as distraction members by helping to provide the necessary clearance between adjacent vertebrae, either in addition to or in lieu of being used in a fusion or other stabilization procedure. 
     In some arrangements, in order to advance and position the implants to a target intervertebral space in a minimally invasive manner, implants are configured to be selectively collapsed or otherwise contracted. In other words, the profile of the implants can be decreased for delivery through a transpedicular passage. Some non-limiting examples of such implants are discussed herein with reference to  FIGS. 13A-16C . However, any other types of expandable/collapsible or generally static implants or other materials can be delivered to a target intervertebral space. 
       FIG. 13A  illustrates an anterior side view of one embodiment of an expandable implant  300  positioned within an interbody space  20 , generally between two adjacent vertebrae  10 A,  10 B. As shown, the implant  300  can comprise an upper support  312 , a lower support  314  and an articulating arm  320  positioned therebetween. As noted above, the implant  300  can be sized, shaped and/or otherwise configured to pass through a passage created within the corresponding vertebra (e.g., the superior vertebra  10 A or the inferior vertebra  10 B) in order to position the implant within the target intervertebral space using a MIS approach. In some arrangements, upon proper deployment of the implant  300  after delivery to and within the interbody space  200 , the upper support  312  is configured to be adjacent to the endplate  15 A of the upper vertebra  10 A, while the lower support  314  is configured to be adjacent to the endplate  14 B of the lower vertebra  10 B. Further, when in the fully deployed or expanded position (as illustrated in  FIG. 13A ), the connecting arm  320  of the implant  300  can be permanently or releasably locked. Thus, the expanded implant  300  can be adapted to maintain a desired separation distance between its opposite supports  312 ,  314 . 
     The quantity, size, shape, location, general configuration and/or other characteristics of the implant  300  can vary in accordance with a specific patient, procedure, desired outcome and/or any other consideration. For example, implants  300  of various sizes and shapes can be provided to allow a surgeon to provide a customized treatment protocol. In addition, the implant  300  can include one or more additional arms or struts  320  to provide additional strength, stability and/or other characteristics of the implant. In other embodiments, one or more additional structures or devices can be delivered to the interbody space (e.g., in one or multiple steps, depending on their size relative to the passage) and advantageously positioned between the upper and lower supports  312 ,  314 . Such structures or devices can advantageously provide additional stability and integrity to the implant. 
       FIGS. 13B and 13C  illustrate the implant  300  of  FIG. 13A  in different stages of expansion or contraction. For example, the implant  300  depicted in  FIG. 13B  is fully contracted or collapsed allowing it to be passed within an opening (e.g., a transpedicular passage, a cannulated access device, etc.). As shown, the fully contracted implant  300  comprises a generally low profile to facilitate moving it through relatively small orifices.  FIG. 13C  illustrates the implant  300  in a partially expanded position, in which the upper and lower supports  312 ,  314  include some vertical separation. According to some embodiments, the implant can be selectively expanded, and thus, the upper and lower supports  312 ,  314  can be spaced from each other, by rotating one of the support members (e.g., the upper support member  312 ) relative to the other support member (e.g., the lower support member  314 ). Thus, once the expandable implant  300  has been delivered to the interbody space and properly positioned relative to the adjacent vertebrae, one or more tools can be used to selectively expand the implant  300 . In the depicted arrangement, such expansion can be accomplished by moving the upper support  312  in a direction generally depicted by arrow  330 . Consequently, the connecting arm  320  can rotate from a generally horizontal orientation to a more vertical orientation, eventually locking the implant  300  into the fully-expanded position (e.g., as illustrated in  FIG. 13A ). 
     Any of the implants disclosed herein, including the embodiment illustrated in  FIGS. 13A-13C , can be moved between a contracted or collapsed position and an expanded position (and/or vice versa) using an actuator. Such an actuator can be mechanical, pneumatic, electrical and/or the like. By way of example, the mechanical implant of  FIGS. 13A-13C  can be expanded and/or contracted using a push/pull rod, wire or another mechanical connector. Such connectors can be coupled to a lever, button, switch, foot pedal or other actuator that a surgeon can manipulate to expand and/or contract the implant  300 . As noted above, in some embodiments, the implant  300  is configured to “lock” or remain in the deployed position once it has been fully expanded. This can help ensure that the upper and lower support member  312 ,  314  will not be compromised following implantation. Alternatively, the implant can be selectively contracted or collapsed following implantation for removal from the anatomy (e.g., through a transpedicular passage, another openings, etc.). Such collapse can be preceded by an “unlocking” of the implant or other step that generally safeguards against the unintended undermining of the implant. 
       FIG. 14  illustrates another embodiment of an expandable implant  400  configured for placement within a target interbody space  200 . As shown, the implant  400  can comprise one or more expandable coils, cables or other members. Such coils or other members  400  can be delivered into the intervertebral space  200  through a transpedicular opening using a minimally invasive approach, while in a coiled or generally contracted state. Once the implant  400  is released into the larger interbody space  200 , it can advantageously expand thereby occupying at least a portion of the space  200 . If an appropriate amount and/or quantity of coiled or expandable materials and/or members are delivered to the interbody space  200 , the implant  400  can provide sufficient structural support to maintain (or, in some embodiments, even increase) a desired distance between the adjacent vertebrae  10 A,  10 B. In some embodiments, the coil comprises nickel titanium (nitinol), another shape memory material, other resilient materials and/or the like. In some embodiments, the cable or other coiled member is delivered within a removable sheath, thereby allowing such a member to remain within a contracted or collapsed state during delivery. As discussed with reference to other embodiments herein, an expandable coil implant and/or any other implant positioned within an intervertebral space can be supplemented by additional structures, reinforcing members, fillers (e.g., cement, grafting materials, etc.) and/or the like, as desired or required. 
     With reference to  FIG. 15 , an implant can comprise an inflatable or fillable balloon  500 , expansion structure and/or other expandable member. The expandable member  500  can be delivered through a transpedicular passage when deflated or contracted and can be subsequently inflated or otherwise expanded once properly positioned within the interbody space  200 . The implant  500  can be expanded using one or more fluids (e.g., air, other gases, liquids, solidifying agents, other mixtures or substances and/or like) through a fill tube which is routed through a passage within the vertebra (e.g., transpedicular passage) and which can be selectively placed in fluid communication with the interior of the implant  500 . The implant  500  can include one or more valves and/or other flow control devices or features to regulate the flow of materials into and/or out of the interior of the implant  500 , thereby controlling the level of expansion and contraction. Such an inflatable or otherwise expandable implant  500  can comprise one or more polymeric, elastomeric, metallic and/or other materials suitable for implantation into a patient&#39;s anatomy. In some embodiments, one or more electrodes and/or other items can be positioned along the outside of the balloon or other expandable member, allowing the clinician to selectively treat or remove tissue within or near the interbody space (e.g., ablate, heat, cool, etc.). 
     Another mechanically-actuated implant  600  configured to be delivered into an intervertebral space  200  is illustrated in  FIGS. 16A-16C . Similar to the arrangement discussed herein with reference to  FIGS. 13A-13C , the depicted implant can selectively transition from a contracted or delivery state ( FIG. 16B ) to an expanded state ( FIGS. 16A and 16C ). According to some embodiments, the implant  600  is removably attached to the distal end of a delivery instrument  610 , which is configured to position the implant  600  into the target intervertebral space  200  (e.g., via a transpedicular passage or other opening). Such an instrument  610  can include a slidable rod or other connector configured to expand and/or contract the implant  600 . In other embodiments, the instrument  610  comprises pituitary-style scissors or another similar device having an actuator (e.g., handle) that allows a surgeon to expand (and/or contract) the implant  600  after delivery to the desired location within an intervertebral space  200 . For example, the proximal end of the instrument  610  can include two scissor-like portions that are opened and closed to change the orientation of the implant  600 . Alternatively, as noted above, one or more other types of actuation devices or features can be used to expand or contract the implant  600 , such as, for example, a pull-rod system, a pneumatic device, an electric device and/or the like. 
     With continued reference to  FIG. 16B , after the implant  600  has been positioned within the interbody space  200 , it can be expanded so that its vertical profile increases (e.g., to extend, at least partially, between adjacent vertebra  10 A,  10 B). In some embodiments, the implant  600  is configured to lock in the expanded position, ensuring that it will not be undermined following implantation. In other arrangements, the implant  600  can be selectively contracted following implantation, as desired or required. 
     As shown in  FIGS. 16A-16C , the implant  600  can include two or more separate portions  620  (e.g., segments, leafs, etc.) that are joined to each other using a hinge  622  or other connection. Thus, in some embodiments, such separate portions  620  can be rotated, translated or otherwise moved relative to each other in order to expand and/or contract the implant  600 . For example, in the depicted arrangement, the segments  620  are configured to rotate in generally opposite directions (e.g., as represented by arrows  630 ,  632 ) upon actuation of the implant  600 . As a result, the implant  600  can lockingly or releasably assume a generally vertical orientation as shown herein. As illustrated in  FIG. 16C , once the implant  600  has been expanded, the corresponding instrument  610  can be detached from the implant  600  (e.g., using one or more actuation devices located on the proximal end of the instrument  600 ) and the instrument  610  can be easily removed from the anatomy (e.g., through a transpedicular passage or opening). As discussed with reference to other embodiments herein, an expandable implant and/or any other implant positioned within an intervertebral space can be supplemented by additional structures, reinforcing members, fillers (e.g., cement, grafting materials, etc.) and/or the like, as desired or required. 
     Tri-Cortical Screws 
     According to some embodiments, a bone screw and/or other fastener can be placed within a transpedicular passage (e.g., as discussed above) or through a similar pathway typically created by a passage within the vertebral member. As a result, the screw can pass through three different bone cortices. Specifically, in some embodiments, the screw passes through the cortex at the pedicle entrance (e.g., along or near the posterior side of the pedicle), the cortex of the pedicle shaft and the cortex of the vertebral endplate. Consequently, such a screw can be referred to as a tri-cortical screw, and the resulting securement as tri-cortical fixation. 
     The use of such tri-cortical screws can provide enhanced fixation and/or one or more other benefits and advantages. For example, tri-cortical fixation can be advantageously associated with higher pull-out strength, as the screw/bone interface is less likely to be undermined when three different cortices are transversed or crossed. Accordingly, these types of screws can provide a more stable fixation than traditional pedicle screw systems. 
     In some embodiments, tri-cortical screws are fully threaded with a cortical (cortex), cancellous or combination (e.g., cortical and cancellous) thread type screw pattern. However, the characteristics of tri-cortical screws can vary, in accordance with a specific procedure or protocol. For example, a screw can comprise threads that extend only partially along its length. Further, tri-cortical screws can include other types of thread patterns (e.g., standard, cancellous, transfixation, etc.), either in lieu of or in addition to cortex type threads and/or features, as desired or required. In addition, as discussed in greater detail below, the type of screw head can vary, depending on the specific application or use. For instance, the screw head can be of the fixed angle, uniaxial or polyaxial type. In other embodiments, the screw comprises a tulip-head pedicle screw configured to receive a rod or other component of a stabilization system. 
     According to some embodiments, the transpedicular or other types of pedicle screws used with the various embodiments of the spinal fusion systems and methods disclosed herein can have one or more varying characteristics along their length. For example, as illustrated schematically in  FIG. 21A , in one embodiment, a pedicle screw S comprises a proximal section A that has a different thread pattern that a distal section B. For example, the proximal section A can include a cancellous thread pattern while a distal section comprises a cortical thread pattern. In some embodiments, the cancellous thread pattern length (section A) comprises approximately 50% to 70% (e.g., about 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70%, percentages between the foregoing values, etc.) of the length of the screw. Thus, in such a configuration, the cortical thread pattern length (section B) comprises approximately 30% to 50% (e.g., about 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50%, percentages between the foregoing values, etc.) of the length of the screw. In other embodiments, however, the cancellous thread pattern length (section A) comprises less than about 50% (e.g., about 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50%, percentages between the foregoing values, etc.) or greater than about 70% (e.g., about 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100%, percentages between the foregoing values, etc.) of the length of the screw. Accordingly, in such embodiments, the cortical thread pattern length (section B) comprises less than about 30% (e.g., about 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30%, percentages between the foregoing values, etc.) or greater than about 50% (e.g., about 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100%, percentages between the foregoing values, etc.) of the length of the screw. In some embodiments, the screw S comprises a cancellous portion (Section A) that is approximately equal in length as the cortical portion (Section B). 
     As noted above, the use of a varying thread pattern along the length of the pedicle screw S can promote more enhanced connection between the screw and the vertebral member or portion thereof (e.g., pedicle, endplate cortex, interior body of vertebra, etc.) through which the screw is passed. For example, the screw  700  disclosed herein with reference to  FIGS. 17A-17D  is configured to pass through the superior endplate of the lower vertebra  10 B. Thus, having a cortical thread pattern along the distal end of the screw can create a stronger and more secure fixation of the screw within the vertebral member. In other embodiments, such as the pedicle screw P illustrated in  FIG. 20 , it may be advantageous to use a screw that includes a cancellous thread pattern along its distal end, as that portion of the screw will terminate within the cancellous portion of the vertebra&#39;s interior body. Thus, in some embodiments, a pedicle screw comprises a cancellous thread pattern along its distal end. The proximal thread pattern can be either cancellous, cortical and/or any other pattern, as desired or required. For example, for the pedicle screw P illustrated in  FIG. 20 , it may be advantageous to have a cortical thread pattern along its proximal end, because that portion of the screw will be located through the cortical surface of the pedicle (e.g., thereby providing for a more enhanced fixation of the screw along its proximal end). 
     In other embodiments, as illustrated schematically in  FIG. 21B , the diameter of the screw (e.g., the outside diameter of the threads, the inside diameter of the threads, etc.), can vary along the length of the screw S′. Such a configuration can be used irrespective of thread pattern. Thus, a proximal section of the screw S′ (Section C) can include a larger diameter, while a distal section of the screw (Section D) comprises a relatively smaller diameter. According to some embodiments, the diameter of Section C can be approximately 0 to 30% (e.g., 0, 5, 10, 15, 20, 25, 30%, percentages between the foregoing values, etc.) larger than the diameter of Section D. However, in other embodiments, the diameter of the larger diameter section (Section C) can be more than about 30% greater (e.g., 30, 35, 40, 45, 50, more than 50%, etc.) than the diameter of the smaller diameter section (Section D), as desired or required for a particular application or use. In still other embodiments, the proximal portion of the screw S′ (Section C) has a diameter that is smaller than the distal portion (Section D). 
     As discussed above with reference to  FIG. 21A , the ratio of the length of Section C to the length of Section D can vary, as desired or required. Further, the thread pattern associated with each of Sections C and D can be customized in accordance with a particular, protocol, procedure or application. For example, in some embodiments, the proximal portion of the screw S′ (Section C) comprises a cancellous thread pattern, while the distal portion of the screw S′ (Section D) comprises a cortical thread pattern. In other embodiments, the proximal portion of the screw S′ (Section C) comprises a cortical thread pattern, while the distal portion of the screw S′ (Section D) comprises a cancellous thread pattern. In yet other embodiments, the entire length of the screw S′ (both Sections C and D) comprises either a cancellous or a cortical thread pattern. 
     One embodiment of a tri-cortical screw  700  secured within a vertebra  10 B using a transpedicular approach is illustrated in  FIGS. 17A-17D . As shown, the screw  700  can be advanced through the pedicle toward and through the superior endplate  14 B of the vertebral member  10 B. In some embodiments, the pathway of the screw  700  is identical to that used to create a passage within the vertebral member. In fact, in some embodiments, the screw is simply inserted within and through the same transpedicular passage used to access the intervertebral space, as discussed in greater detail above. In some embodiments, the outside diameter of the screw or other fastener  700  is similar or slightly larger than the insider diameter of the passage through the vertebral member. This can help ensure that the screw is properly secured within the passage and that it will not become loose or dislodged after implantation. By positioning the screw or other fastener  700  through the same transpedicular passage that is used to access a target intervertebral space, collateral damage to the corresponding vertebrae is reduced or minimized, as the need for a separate opening through the vertebrae is eliminated. In other arrangements where a passage through the vertebral member has not been created, the screw or other fastener can be similar or substantially similar to that of the transpedicular passages or other openings discussed above with reference to  FIGS. 1A-6D . 
     The screw  700  can be placed within a targeted vertebra  10 B under direct vision using a minimally invasive (e.g., MIS) open, mini-open, arthroscopic or any other approach. For example, in keeping with the overall theme and advantages provided by the various embodiments disclosed herein, the screw can be positioned within the target vertebral member minimally invasively, thereby eliminating the need to perform more complicated and risky tissue retraction/distraction techniques and/or the like. In some arrangements, the tri-cortical screw or other fastener  700  can be delivered through a tube/narrow retractor. In other embodiments, the pedicle screw  700  can be placed within the target pedicle P of the vertebra  10 B percutaneously, over a guidewire, using fluoroscopic guidance (or with the assistance of some other imaging technology) and/or using any other tool, technique or approach. For instance, the screw  700  can be guided through the vertebra using a guidewire G situated within a transpedicular passage (e.g., see  FIGS. 2A-2D ). 
     As noted above, the screw  700  can include any one of a variety of head types, such as, for example, fixed angle, uniaxial or polyaxial. With direct vision, a rod (not shown) can be directed across the screw heads  720  of the various pedicle screws  700  that have been secured to various vertebrae of a patient&#39;s spine. For example, as discussed in greater detail below, the screw  700  can be one component of a spine fusion and stabilization system. The screw  700  can be coupled to and fastened with (e.g., using a rod, another direct or indirect connection or joint, etc.) to another pedicle screw or fastener (e.g., secured to one or more other vertebrae), to a facet fixation implant and/or the like. In some embodiments, a rod or other fixation component can be directed across the screw heads from the distal screw of the fixation system to the proximal screw. In some embodiments, the head of the pedicle screw  700  is not configured to receive a rod or other component of a fixation system. In addition, the pedicle screw  700  can be cannulated or non-cannulated, as desired or required. A cannulated screw can be guided through a transpedicular passage or opening over a guidewire, as discussed herein. 
     Further, the thread pattern type, size, orientation and/or other details of the screw or other fastener  700  can vary, as desired or required. In some embodiments, the screw  700  comprises a cortex type pattern across all or substantially all of its length. Alternatively, the thread pattern can be of a different type and/or can extend only partially along the shaft of the screw, in accordance with a specific application or use. 
     According to certain embodiments, a screw inserter can be used to secure a pedicle screw  700  to a vertebra  10 B using a transpedicular/tri-cortical approach, as discussed herein. In such arrangements, the screw inserter can be of sufficient length so as to protrude outwardly form the patient&#39;s access wound, even when fully seated within the vertebra. This can permit the screw inserter to serve as a reference point or landmark to assist in guiding a rod or other component of a fixation system across the various pedicle screw heads. 
     Screws secured using the transpedicular/tri-cortical approach disclosed herein can be used as a part of a standard posterior fixation of vertebrae (e.g., in a primary thoracic, lumbar and/or sacral fusion). In some embodiments, the pedicle screws discussed herein, or alternatives thereto, are inserted into the corresponding vertebrae with the assistance of standard or non-standard instrumentation. In addition, as applies, for example, to all unicortical versus bicortical screw fixation, the use of such tri-cortical pedicle screws can provide stronger pull-out strength fixation in all patients, including patients with various degrees of osteopenia/osteoporosis. Further, because of their higher pull-out strength, such screws can help salvage loosened screw holes from a pseudoarthrosis that requires reinstrumentation, (e.g., instead of simply using a much larger diameter screw). In other embodiments, a tri-cortical pedicle screw can comprise a transfixation screw positioned across the disc or interbody space  200 . Thus, the screw  700  can extend into the cephalad vertebral endplate  15 A. 
     Facet Joint Preparation and Implants 
     According to some embodiments, one or more facet joints are prepared for receiving one or more implants and/or other items therein. Such implants can promote fusion of the facet joint and/or provide distraction between adjacent vertebrae. As discussed in greater detail herein, the fusion of the facet joint can be used, either alone or in combination with another spinal fusion system or procedure, to stabilize and/or fuse a portion of a patient&#39;s spine or otherwise treat a particular spinal defect or ailment. According to some embodiments, access to the facet joints, preparation of the joints, delivery of one or more implants and/or other required steps are advantageously performed using minimally invasive approaches. 
     In some arrangements, in order to access the facet joints of a targeted portion of the spine, bilateral, posterior incisions are made through the skin and fascia of the patient. In some embodiments, such incisions are generally short and are located immediately distal and lateral to the pedicles (e.g., at or near the junction of the pars and transverse process) of the inferior vertebral body at the proposed fusion level. The surgeon can then use a generally blunt and flat probe to perform a blunt dissection through the muscular layer of the patient. In some embodiments, the probe is cannulated so that a guidewire and/or any other appropriately sized device or item can be selectively passed therethrough. In some arrangements, dissection through the patient&#39;s muscle layer generally approximates the avascular plane of the Wiltse approach. 
     Once the patient&#39;s muscle layer has been dissected, the probe can be directed toward the distal/inferior aspect of the facet joint and tamped therein. In some embodiments, the probe is tamped approximately two-thirds of the way cephalad-anterior into the joint. Further, according to some arrangements, anteroposterior (AP) fluoroscopy is adjusted to approximately 15 to 20 degree oblique (e.g., depending on the level of the thoracic or lumbar spine facet joints) to assist with the advancement of the probe into the facet joint. The position of the probe can be confirmed by the oblique AP and lateral views. For example, using a lateral view, the surgeon can use a probe trajectory that maintains the probe tip posterior to the neural foramen. Once the probe has been adequately advanced into the joint, a guidewire can be passed through the lumen or opening of the cannulated probe and secured to the proximal end (e.g., proximal one-third) of the facet joint. In some embodiments, the guidewire comprises a sharp and/or a threaded tip to facilitate securement to the joint. The guidewire can be fixed or otherwise secured to the proximal third of the joint using an interference fit, by penetration into the cephalad aspect of the facet joint or joint capsule and/or via any other attachment method, as desired or required. 
     Once the guidewire has been secured relative to the facet joint, the cannulated probe can be removed from the anatomy. In some embodiments, the chondral surfaces of the superior and/or inferior facet surfaces of the joint are then at least partially removed. For example, a rasping tool or other tool or device having one or more abrading surfaces can be inserted within the facet joint and moved in a manner that causes removal of the cartilage from one or more portions of the joint. In arrangements where a guidewire extends into the facet joint, a cannulated rasping or other abrading tool can be used. Alternatively, however, such a rasping or abrading tool does not need to be cannulated. Accordingly, the tool can be directed into the facet joint without the assistance of a guidewire, as desired or required by a particular protocol. 
     With reference back to  FIGS. 7A and 7B , a probe or tool  800  having a rasping surface can be selectively placed within a facet joint. As shown, the rasping tool or probe  800  can include a handle  810  along its proximal end. An elongated shaft  820  can extend from the handle  810  toward the distal end of the probe  800 . In some embodiments, as depicted in  FIGS. 7A and 7B , the distal end of the probe  800  comprises a rasping or abrading head  830  that is adapted to selectively remove cartilage, bone and/or other tissue from anatomical surfaces. The head  830  can include one or more abrading structures or features  834 . For example, in some embodiments, the abrading structures  834  include a plurality of protruding members that generally extend radially outwardly (e.g., directly outwardly, at any angle relative to the longitudinal axis of the tool  800 , etc.). In other embodiments, other types of abrading structures or features (e.g., recesses, sharp edges, etc.) are used, either in lieu of or in addition to those illustrated in  FIGS. 7A and 7B . 
     In some embodiments, the rasping tool  800  comprises one or more interior lumens  840 . Thus, a user can advance the tool  800  into a targeted joint (e.g., a facet joint) over a guidewire, as discussed in greater detail herein with reference to other embodiments. In other arrangements, however, a rasping tool can be positioned within a facet joint and/or selectively manipulated therein without the assistance of a guidewire. For example, the tool  800  can be accurately positioned within a joint with the assistance of imaging technology (e.g., fluoroscopy), either with or without the assistance of a guidewire, as desired or required. 
     According to some embodiments, the rasping tool  800  is tamped within the facet joint (e.g., approximately two-thirds deep into the joint). Once within the joint, the tool  800  can be manipulated (e.g., moved into and out of the joint) in order to accomplish a desired abrasion effect on the adjacent chondral surfaces of the joint. In some arrangements, the rasping tool  800  is used to remove, at least partially, chondral layers of the superior and/or inferior facet surfaces and/or to cause the facet joint to bleed. As discussed in greater detail herein, such preparation of the chondral surfaces of a facet can help promote the subsequent fusion of the treated joint. Depending on the exact configuration of the rasping or abrading tool used, the desired level of abrasion of the chondral surfaces and/or one or more other considerations, the tool can be moved into and out of the facet joint either once or multiple times (e.g., two times, three times, four times, five times, more than five times, etc.). 
     Once the facet joint has been adequately abraded and/or otherwise prepared, the abrading tool  800  can be removed (e.g., by retracting the tool over the guidewire). In some embodiments, with its adjacent facet surfaces adequately abraded, the facet joint can then be permitted to fuse. Facet joint fusion can be accomplished through prolonged contact between the facet subchondral decorticated bony surfaces. Alternatively, one or more screws, other fasteners, other securement devices or features, implants and/or the like can be inserted within or near the facet joint to facilitate the fusion process. Regardless of which approach is used, relative immobilization of the adjacent facet surfaces may be desired to properly complete the fusion procedure and to ensure that it will not be compromised after the procedure. 
     According to some embodiments, one or more implants are positioned within a target facet joint, either with or without the use of a guidewire. Fluoroscopy and/or other imaging tools or technologies can be used to accurately and safely position an implant into a joint (and/or subsequently manipulate the implant within that joint), as desired or required. For instance, in one embodiment, an implant is placed over a guidewire and advanced into a facet joint using the confirmation of AP and lateral fluoroscopy. According to some embodiments, a standard or non-standard implant inserter is used to advance an implant into the facet joint. In some arrangements, the inserter or similar device includes one or more drill guides configured to assist the surgeon in accurately penetrating one or more portions of the inferior and/or superior facet surfaces during a subsequent drilling procedure. 
     By way of example, the drill guide on the inserter device can be offset by approximately 2 to 5 mm medial and lateral to the facet joint plane. However, the offset, spacing and/or other details related to the drill guide can vary, as desired or required by a particular procedure or protocol. With the assistance of drill guide(s), imaging technologies (e.g., fluoroscopy) and/or any other guiding device or method, a drill can be used to create one or more passages through the bones that comprise the facet joint. In one embodiment, a drill is driven into the inferior facet subchondral bone with parallel trajectory to the facet joint plane using an AP or oblique fluoroscopy view. The trajectory of the drill, and thus the passage that is created therethrough, can be generally in line with the facet joint and pars interarticularis using a lateral fluoroscopy view. In some arrangements, the trajectory remains, at all times, posterior to the neural foramen. In some embodiments, an awl-tipped type drill is used to penetrate the inferior facet subchondral bone. Further, the drill can be either hand-driven or power-driven, as desired or required. Any other type of bone drill or other advancement device can be used. 
     After creating the desired passage(s) through the bone(s) of the inferior facet, the drill can be removed. Subsequently, a screw or other fastener can be advanced into the target facet and positioned within a passage created by the drill. In some embodiments, a screw is passed into the inferior facet through the medial drill guide to secure an implant to the proximal vertebrae. In other arrangements, a screw can be passed into the superior facet through a corresponding guide and/or opening, either in lieu of or in addition to an inferior screw. Regardless of the exact securement details, an implant can be adequately maintained within the targeted facets to promote fusion of such joint. In some embodiments, bone grafting materials, bone cement and/or the like can be used between and/or near the facet joint to further promote fusion. 
     In addition, as discussed in greater detail above, a passage can be created through the pedicle toward the corresponding superior endplate of the vertebra. Such a transpedicular passage, can be initially created using a drill (e.g., cannulated drill) and subsequently enlarged and/or safeguarded using one or more taps, cannulae (e.g., threaded cannulae) and/or the like, either with or without the use of a guidewire. As noted above, a transpedicular opening or passage can advantageously provide access to the corresponding interbody or intervertebral space. For example, as discussed in greater detail herein, a pituitary-rongeur-like device or other sampling device can be advanced through the transpedicular opening into the interbody space for biopsy and/or sampling of target tissue (e.g., disc material, endplate cartilage, vertebral bone, etc.). In other embodiments, a brush or other tissue abrading device can be advanced through one or more transpedicular passages in order to selectively remove or abrade disc material and/or endplate cartilage/bone and/or otherwise prepare tissue positioned within or near the intervertebral space. Relatedly, one or more materials (e.g., bone grafting agents, putty, nucleus filler materials, other fillers, expandable implants, other interbody implants, etc.) can be delivered into a target interbody space via the transpedicular openings. 
     According to some embodiments, a facet joint implant comprises a unitary (e.g., monolithic) structure or a multi-part design (e.g., having two or more components). For example, as illustrated in  FIGS. 18A and 18B , a facet joint implant  1000  can comprise two separate portions  1010 ,  1020  that are configured to advantageously engage one another (e.g., lockingly, non-lockingly, etc.) after implantation. As shown, a first implant portion  1010  can be configured to secure to one of the facet surfaces F 1  (e.g., inferior or superior), while the second implant portion can be configured to secure to the other facet surface F 2 . The opposing portions  1010 ,  1020  can be implanted into the adjacent facet surfaces (e.g., chondral tissue, subchondral bone and/or the like) using one or more protruding portions or features  1016 ,  1026 , screws, other fasteners and/or the like. As depicted in  FIG. 18A , each portion  1010 ,  1020  can be secured to the adjacent tissue using a single fastener or feature  1026  or using two or more fasteners or features  1016 ,  1016 ′, as desired or required. 
     With continued reference to  FIGS. 18A and 18B , a facet joint implant  1000  can comprise a ratchet-like configuration or design that permits selective relative translation (e.g., proximal, distal, etc.) of the opposing portions  1010 ,  1020 . For example, each of the portions  1010 ,  1020  can comprise a plurality of teeth  1014 ,  1024  or other protruding or engagement members that are shaped, sized and otherwise adapted to mate or interdigitate with teeth or other protruding members along the opposite portion  1020 ,  1010 . In some embodiments, the use of such complementary teeth  1014 ,  1024  allows for proximal translation of the inferior facet of an upper vertebra relative to the superior facet of the immediately lower vertebra. Consequently, such a ratchet design can advantageously permit for indirect decompression of the neural foramen and lateral recesses by translation of one implant portion  1010 ,  1020  relative to the opposing portion  1020 ,  1010 . Once a desired relative translation between the opposing portions of the implant has been achieved, the portions can be advantageously secured to one another using one or more permanent or releasable attachment method or devices, such as, for example, screws, tabs, pins, other fasteners, adhesives, welds and/or the like. The insertion of implant into the facet joint and any subsequent steps or procedures (e.g., distraction, fixation of one portion of the implant to another portion, etc.) can be advantageously performed using a minimally invasive approach. 
     In some embodiments, as depicted in  FIG. 18B , a facet joint implant comprises a generally oval or rectangular shape. The thickness of the implant can be approximately 2 to 4 mm. Such a thickness can advantageously permit the implant to fit within the plane of a facet joint. Further, in some configurations, the implant extends approximately two-thirds of the way across the anterior-posterior dimension and/or the caphalad-caudad dimension of the facet joint. In other arrangements, however, the shape, thickness, other dimension (e.g., length, width, etc.) and/or other characteristics of the implant can vary, in accordance with a specific protocol or procedure. For instance, the facet joint implant can include a generally circular, other polygonal (e.g., triangular, hexagonal, octagonal, etc.) or irregular shape. In addition, the thickness of the implant can be less than about 2 mm or greater than about 4 mm. As noted above, in other embodiments, a facet joint implant comprises a simpler unitary (e.g., one-part or monolithic) structure. 
     Accordingly, in some embodiments, as discussed in greater detail herein, adjacent vertebrae can be immobilized relative to each other by fusion of adjacent facet surfaces, by fusion of adjacent endplate surfaces and/or by fusion systems that attach a first screw, fastener, implant or other device to another a second (or additional) screw, fastener, implant or other device. Thus, the facet surfaces of adjacent vertebrae can be fused to each other (e.g., with or without the assistance of one or more implants). Facet fusion can be supplemented by one or more additional components of a fusion system, such as, for example, one or more transpedicular screws inserted into in one or both of the vertebrae corresponding to the facet joint implant. In addition, transpedicular access into the patient&#39;s corresponding intervertebral or interbody space can be used to perform one or more procedures, such as, for example, removal of disc and/or other native material, preparation of endplates for fusion, delivery of grafting agents, other fusion-promoting implants and/or the like.  FIGS. 19A-19B  illustrate various views of adjacent vertebrae  10 A,  10 B that comprise facet joint implants  1100 . The illustrated embodiment of a fusion system also comprises one or more transpedicular screws  700  or other fasteners that extend from the pedicles of the lower vertebra  10 B into the interbody space  20 . Such screws  700  can be inserted into passages or other openings that are created within the vertebra. As discussed in greater detail herein, such passages advantageously provide access (e.g., using minimally invasive approaches) to a target interbody or intervertebral space. 
     According to some embodiments, as illustrated in  FIGS. 19A-19D , the portion of the facet joint implant  1100  adjacent the facet surface of the lower vertebra  10 B is secured to the transpedicular screw  700  that is routed through the lower vertebra  10 B and into the intervertebral space  20 . The opposite portion of the facet joint implant  1100  (e.g., the portion that is adjacent the facet surface of the upper vertebra  10 A) is secured to the upper vertebra  10 A. For example, in the illustrated embodiment, this opposite portion of the facet joint implant is secured to the lamina of the upper vertebra  10 A using a screw  1150  (e.g., a lamina screw) or other fixation device or method. In some embodiments, each of the opposing portions of the facet joint implant  1100  are fixedly (e.g., directly or indirectly) secured to the corresponding screw or other fixation system. For example, the facet joint implant section can include a ring or other extension through which the corresponding screw (e.g., the transpedicular screw  700  or the lamina screw  1150 ) may pass. In other embodiments, one or more intermediate connectors (e.g., rods, welds, tabs, etc.) are used to connect the facet joint implant  1100  to the corresponding screw  700 ,  1150  or other fixation system. 
     According to some embodiments, once the facet joint implant  1100  has been properly secured to both the upper and lower vertebral members  10 A,  10 B (e.g., using corresponding screws  1150 ,  700  or other fixation devices), and the opposing portions of the facet joint implant  1100  have been properly secured to each other, relative movement between the upper and lower vertebral members  10 A,  10 B can be achieved, thereby stabilization that portion of the spine, promoting fusion and/or the like. In some embodiments, to further stabilize the spine, to provide more enhanced fusion and/or to provide one or more other benefits or advantages, the fusion system illustrated in  FIGS. 19A-19D  can be further supplemented. For example, in one embodiment, the fusion system can additionally include a second bone screw (e.g., pedicle screw P) positioned within the upper vertebra  10 A, as illustrated in  FIG. 20 . In such a configuration, a rod R, connector or other fixation system component can be used to connect the transpedicular screw  700  positioned through the lower vertebra  10 B to the pedicle screw P of the upper vertebra  10 A. 
     In other embodiments, an implant (e.g., expandable implant, coiled implant, inflatable implant, etc.), grafting material and/or any other device or member can be positioned within the intervertebral space  20  between the vertebrae  10 A,  10 B. In some embodiments, such devices and/or materials can be advantageously delivered to the intervertebral space  20  through the transpedicular passage before the screw  700  is positioned therethrough. 
     For any of the embodiments disclosed herein, it will be understood that the procedures performed on a first lateral side of the spine can be performed on the opposite, second lateral side, either instead of or in lieu of the first lateral side. Thus, in some embodiments, a spine fusion system can include two transpedicular screws within the same vertebral member (e.g., one through each pedicle). Alternatively, a system can include a transpedicular screw only through one pedicle, as desired or required. Similarly, the fusion system can include facet joint implants along one or both joints between two adjacent vertebrae. 
     Therefore, in reference to  FIGS. 19A-19D , a minimally invasive approach can allow the surgeon to perform a fusion procedure while accessing only a small area of the patient&#39;s spine (e.g., the area posterior to one or more pedicles). For example, access to such a relatively small area can allow the surgeon to create transpedicular openings from the pedicle to the interbody space  20 . As discussed herein, the resulting passage can permit the surgeon to clean out the disc space and/other native tissue within the intervertebral space  20 , deliver implants, grafting materials and/or the like and/or perform one more procedures. At the same time, such access to the pedicle can allow the surgeon to insert a transpedicular screw  700 . In addition, a facet implant  1100  can be positioned within the facet joint and fixed to the adjacent vertebrae  10 A,  10 B. As discussed herein with reference to  FIGS. 18A and 18B , in some embodiments, the facet joint implant is configured to provide some distraction between adjacent vertebrae before the position of the implant  1100  becomes fixed. 
     As discussed above with reference to the bone screw embodiments schematically illustrated in  FIGS. 21A and 21B , the transpedicular screw  700  can include a cortical thread pattern along its entire length. In other embodiments, its thread pattern can be cortical at least along its distal end (e.g., where it passes through the cortical portion of the endplate  14 B) and/or along its proximal end (e.g., where it passes through the cortical portion of the pedicle). Further, with reference to  FIG. 20  below, the pedicle screw P that is positioned through the upper vertebra  10 A can include a cancellous thread pattern along its distal end (e.g., where it is positioned within the cancellous interior portion of the vertebral body  10 A) and a cortical thread pattern along its proximal end (e.g., where it passes through the cortical portion of the pedicle). This can provide more secure fixation between the screws  700 , P and the respective vertebral members. 
     In other embodiments, the facet joint implants and other fusion procedures described herein can be combined with one or more other stabilization systems or devices to provide an enhanced fusion system and method. For example, facet joint fusion systems and techniques (e.g., with or without the use of facet joint implants) can be used in conjunction with pedicle screw and rod systems and/or the like. In some embodiments, such supplemental stabilization systems can include pedicle screws having a transpedicular orientation, as discussed in greater detail herein. 
     One embodiment of a spinal fusion system that comprises a transpedicular screw  700  and a facet implant  1100  that are coupled or otherwise fixedly connected to one another is illustrated in  FIGS. 19A-19D . The screw  700  and the facet implant  1100  can be joined directly or indirectly (e.g., using an interconnecting rod or other connection device). In some embodiments, with such a fusion system, the superior vertebra  10 A is secured to the inferior vertebra  10 B in a manner that can prevent or reduce the likelihood of relative movement. Thus, such a fusion system can maintain the two vertebrae is a generally fixed relationship relative to one another. The fusion between the two vertebrae can be further enhanced if a transpedicular access is used to deliver an implant, grafting material and/or the like between the two adjacent endplates of the vertebral members  10 A,  10 B. Thus, in such embodiments, the vertebrae are fused both at the facet joint and the between the endplates, thereby providing for enhanced fusion. 
     In some embodiments, adjacent vertebrae are stabilized relative to each other using rod or other interconnecting system. For example, as illustrated in  FIG. 20 , a transpedicular screw  700  inserted through the pedicle of the inferior vertebra  10 B can be connected to a pedicle screw P positioned through the superior vertebra  10 A. As with any other embodiments disclosed herein, screws may be positioned on one or both sides of the pedicles, as desired or required. 
     With continued reference to  FIG. 20 , the screw on the superior vertebra  10 A can include a typical pedicle screw P. In other embodiments, however, the upper screw P can comprise a transpedicular screw (e.g., similar to the screw positioned through the pedicle of the inferior vertebra  10 B), as desired or required. This can be particularly helpful if access is required to the intervertebral spaces located both above and below the superior vertebra  10 A. Regardless of their exact position, orientation and/or other details, the screws  700 , P can comprise tulip head designs to receive a rod R or other securement system. In some embodiments, the fusion system illustrated in  FIG. 20 , which includes two screws and a rod R or similar securement system, can also comprise one or more facet implants (such as, for example, the fusion implants disclosed herein with reference to  FIGS. 18A-19D ). Therefore, in such a configuration, adjacent vertebrae are maintained relative to each in one, two or three different manners—by the facet implant, fusion between adjacent endplates and the rod system extending between two or more pedicle or bone screws  700 , P. 
     Transpedicular/Tricortical Pedicle Screw 
     As shown in the embodiment of  FIGS. 22A and 22B , a screw  2040  can be placed from posterior entry approach through the pedicle (e.g., of the thoracic, lumbar, or sacral vertebra) across the cortex of the central third of the superior endplate of the same vertebra  10 B. The leading end/tip  2042  of the screw  2040  can be positioned such that it will buttress/support the inferior endplate of the vertebra above  10 A (e.g., thus acting to potentially distract the interbody space/create lordosis/create foraminal decompression/or restore disk height, etc.). The leading end/tip  2042  of the screw  2040  could be round or flat or possibly could have surface contact area enlarged (by scissoring or unfolding) just prior to abutting the inferior endplate above. In some embodiments, the screw  2040  is cannulated, allowing for cement or other filler to be delivered to the distal end (e.g., to close the gap between the distal end of the screw and the adjacent vertebra  10 A). In some embodiments, once rested against the inferior endplate of the superior vertebra  10 A, the screw can serve as a structural graft of the interbody space, supplemented by the posterior of the fixation. 
     With continued reference to  FIG. 22A , a stabilization or fusion system can further include a second screw  2050  positioned through the superior vertebra  10 A. One or more rods, plates or other interconnection members  2060  can be used to connect the two screws  2040 ,  2050  (and/or additional screws) to one another, as desired or required. 
     Quadruple Ribbon Deployable Diskectomy Tool 
     One embodiment of a diskectomy tool  2500  is illustrated in  FIG. 23 . As noted herein, such tools can be used to selectively remove native tissue (e.g., endplate, disk, etc.) from within and/or around a targeted intervertebral space. As shown, the tool  2500  can include an outer tube  2510  with a centrally placed narrow metal rod  2512 . In some embodiments, the rod  2512  is slidably positioned within the outer tube  2510 . In some embodiments, the device  2500  comprises a total of four orthogonally positioned metal ribbons  2520  positioned along the distal end of the device. In other embodiments, more (e.g., 5, 6, 7, 8, more than 8, etc.) or fewer (e.g., 1, 2, 3) ribbons or other members  2520  can be used. As shown, the ribbons  2520  can be fixed to or near the distal tip of the central rod  2512  distally and to the side of the tube  2510  proximally. In some embodiments, when the central rod  2512  is retracted in the tube  2510 , the ribbons (which may, e.g., comprise Nitinol, other shape memory materials, other metals or alloys, other materials, etc.) can expand (e.g., protrude, balloon, etc.) outwardly. As a result, when the tool  2500  is rotated during use, the radially expanded ribbons  2520  can cut or otherwise abrade tissue. For example, in some embodiments, the ribbons  2520  can widen a space within the intervertebral space, can remove endplate material, disk material and/or cartilage from the subject. 
     Diskectomy (Pituitary/Curette) Tool 
       FIGS. 24A and 24B  illustrate different views of another embodiment of a diskectomy tool  2600 . As shown, the tool  2600  can include a working end  2604  along its distal end. The working end  2604  can be deployed to different positions of action with scissoring action of a hand grip  2606 . When inserted within a subject minimally invasively (e.g., through the transpedicular pathway), the curette tip  2604  can remain in the closed position (as illustrated in  FIG. 24A ). However, once the working tip  2604  has been passed into the disk space or other target area of the subject&#39;s anatomy, it could be deployed with the scissoring hand action (e.g., manually held in position or ratcheted to a fixed position). The curetted end  2604  of the instrument could slide back and forth for the curette action on the superior endplate of the same vertebra or the inferior endplate of the vertebra above. As shown, the working tip  2604  of the device  2600  can include two portions that selectively rotate relative to one another by actuation of the handgrip assembly  2606 . For example, in one embodiment, the tip  2604  comprises a fixed portion  2634  (e.g., that could be an extension of the device&#39;s main shaft  2610 ) and a movable (e.g., rotatable) portion  2632  that include one or more abrasive surfaces, edges and/or features. 
     Pedicle Screw/Lamina Screw Fixation/Translation/Distraction Plate. 
     As discussed herein with reference to  FIGS. 19A-19D , a stabilization system can include a translaminar screw and a transpedicular screw that are secure to each other using one or more couplings or other devices. Such systems can offer a reliable and stable way of stabilizing a portion of the spine using a completely minimally invasive approach.  FIG. 25  illustrates one embodiment in which a translaminar screw  3060  and a transpedicular screw  3040  are mechanically coupled to one another using a coupling or other device  3080  (e.g., rod, plate, etc.). Such a coupling  3080  can be fixed or adjustable, as desired or required. Further, an additional set of screws  3040 ,  3060  and coupling  3080  can be positioned along the opposite side of the subject&#39;s spine. 
     One embodiment of an adjustable fixation coupling or plate  3190  can be used to couple a transpedicular interbody screw or tricortical screw to a translaminar screw is illustrated in the various views of  FIGS. 26A-26F . With specific reference to  FIG. 26A , the fixation plate  31080  can fix to the heads of the two screws and can include an internal mechanism to incrementally and selectively distract the screw heads apart. As shown, the plate  3190  can also include a locking mechanism (e.g., opening  3194  for a locking screw, which when properly inserted into the opening  3194 , prevent movement of a first portion  3182  relative to a second portion  3190 ). Thus, the amount or degree of distraction can be adjusted and maintained. In one embodiment, the transpedicular screw is configured to be inserted within an opening  3184  of the first portion  3182  and the translaminar screw is configured for placement in an opening  3192  of the second portion  3190 . The portions  3182 ,  3190  can be configured to move relative to one another using a ratcheting system. The distracted position may be favorable to allow for foraminal distraction/decompression of nerve roots in the foramen and lateral recesses. The fixation can be beneficial to provide stability for fusion purposes. In some embodiments, the plate  3180  can be placed over or near the facet joint, and it may or may not have an opening through which bone graft could be packed into the facet joint after plate placement. In some embodiments, one or more openings through the plate  3180  can be beneficial to allow radiographic assessment of fusion. 
     Improvements to System and Related Methods 
     According to some embodiments, the systems, devices and/or related methods described herein can be used for any viable approach, including posterior access to the subject&#39;s intervertebral disk space for the thoracic, lumbar and/or lumbosacral portions of the spine. In some embodiments, as described herein, an approach can be achieved through unique portal access from the posterior spine, through the pedicle, penetrating the superior endplate of the vertebral body and entering the intervertebral disc space. 
     As also discussed herein, one or more static and/or expandable implants can be inserted through one or both of the bilateral pedicle access portals into the targeted intervertebral space. In some arrangements, the insertion of such implants can be performed following one or more preparatory steps. For example, the practitioner can prepare the disc by one or more discectomy procedures (e.g., accomplished with a series of discectomy tools, such as, for example, curettes, endplate scraping tools, disc/soft tissue removal tools, etc.) performed through the same pedicle portal. 
     According to some embodiments, an expandable implant could include a mechanical implant that is narrow enough and/or otherwise sized and configured to pass through the pedicle portal and then expanded/deployed into a larger, taller, expanded and/or different position or orientation after being placed into the targeted intervertebral or disc space. In some embodiments, two or more expandable implants can be used in a targeted intervertebral or disc space, as desired or required. 
     In some embodiments, one or more expanded implants inserted into the intervertebral or disc space can help create structural support, create increased disc height for indirect neural element decompression, create increased lordosis for sagittal plane parameter restoration and/or one or more advantages or benefits, as desired or required. Also, according to some arrangements, the addition of synthetic and/or natural bone grafting materials into the targeted intervertebral or disc space between and surrounding the implant(s) can further assist with bony fusion of the disc space. In some embodiments, such materials can be inserted with the delivery of the implant(s) and/or before or after the delivery of such implants. The grafting materials can at least partially (e.g., partially, completely, etc.) occupy the intervertebral or disc space or portion thereof. 
     According to some embodiments, the implant can comprise, at least partially (e.g., partially or completely) one or more suitable materials, including, without limitation, metal and/or a metal alloy (e.g., stainless steel, titanium, etc.), bone, PEEK and/or other materials, as desired or required. In some embodiments, one or more surfaces or portions of the implant include textured or ingrowth surfaces that allow for the surrounding bone to grow, at least partially, into the surface of the implant. 
     In some configurations, an additional implant type includes a collapsed container made from a pliable or flexible (e.g., non-rigid, non-semi rigid, etc.) material or structure. For example, such implants can include one or more natural and/or synthetic materials that are at least partially (e.g., partially, completely, etc.) absorbable or not absorbable, including cloth, other fabric, mesh, membrane (e.g., polymeric, other natural or synthetic, etc.), film, or other type material. In some embodiments, such implants are narrow and/or are otherwise configured in such a manner that they can pass through, in a collapsed configuration, the transpedicular portal or pathway into the prepared disc space. 
     The implant can be inserted into the targeted intervertebral or disc space via a medial, lateral, posterior and/or any other pathway from the pedicle access portal entrance to the superior endplate/disc space. The collapsed implant, once positioned, can be filled, at least partially, with bone or other grafting materials (e.g., in a putty, pellet, morselized bone, powder, or other particulate shape/consistency). Such grafting material can be provided using a tube or other insertion or implant type device. 
     Once filled, at least partially, the expandable container or other implant can be configured to abut (e.g., partially, completely) in order to support and/or expand the superior and inferior endplates of the intervertebral disc space to restore height, indirectly decompress neural elements, correct deformities (such as scoliosis, kyphosis, spondylolisthesis, etc.), increase lordosis, provide structural support, help with fusion of the intervertebral segment and/or provide one or more advantages or benefits. 
     According to some embodiments, one or more additional features or components can be included. For example, the procedure/implant system can include one or more screws (e.g., transpedicular interbody screws, other bone screws, etc.) that are placed, for example, from the posterior entry point of the pedicle, across the superior endplate into the intervertebral disc space with or without contact with the inferior endplate of the vertebral body above. In some embodiments, a screw head may be a “tulip” type or other type of head that is configured to receive and/or fix to a rod or other connecting member. 
     In some embodiments, such a rod or other connecting member can be sized, shaped and/or otherwise configured to connect to one or more other screws or fixation elements (e.g., a cortical screw, a laminar screw, a facet screw, another type other traditional type pedicle screw. Such screws can have a thread type, pitch, pattern and/or other configuration along its length and/or along any other portion to provide enhanced (e.g., improved, enhanced, optimal, etc.) fixation along the various sections of bone and bone types that it is placed through (e.g., cortical, cancellous, pedicle, osteoporotic or normal bone density), as desired or required. In some embodiments, a screw has a cortical and/or a cancellous thread pattern. The screw can include one or more segments or portions that have no thread, and it may also partial or total textured, bead blasted, machined, or 3D printed surfaces for the purpose of allowing and/or facilitating fusion to occur from the vertebrae above and below into the screw surface. In some embodiments, there may also be an articulated or fixed screw tip that is shaped/configured to provide maximal surface area contact with the vertebral inferior endplate above and/or superior endplate below. 
     In some embodiments, an implant is advanced or otherwise placed into the targeted intervertebral space through the transpedicular bony channel through the superior endplate. In some embodiments, the implant placed into the intervertebral space is at least partially expandable. As noted herein, the expandable implant may be expanded mechanically, by filling a fillable member positioned into a targeted intervertebral space and/or the like. For example, in some embodiments, the expandable implant is selectively expanded by filling a pliable sac or flexible container or retaining member with a filling material such as a fluid, a putty, a grafting material and/or the like. The expandable sac or other container can be at least partially (e.g., partially, completely, etc.) impervious or porous and may be absorbable or non-absorbable, as desired or required. 
     In some embodiments, the expandable implant can be configured to expand along (or substantially along) the cephalad-caudal axis, the medial-lateral direction and/or the anterior-posterior direction. In some embodiments, expansion of the implant can permit enhanced (e.g., increased or maximum) contact with bony surfaces, including, without limitation, the adjacent superior endplate of the first vertebral body and the inferior endplate of the second vertebral body. Such a configuration can allow or increasing the likelihood of allowing for structural support, increasing the likelihood of bony fusion, permit at least partial distraction of vertebral bodies or vertebrae (e.g., adjacent vertebral bodies or vertebrae) and neural foramen for indirect decompression, increase the likelihood of lordosis creation between the vertebral bodies and/or any other goal. 
     According to some embodiments, the implant comprises a mechanical device. For example, the implant can be configured to expand along the cephalad-caudal axis (or substantially along the cephalad-caudal axis) using a screw, a ratchet, a wire, another compression mechanism and/or any other device, feature or technology to allow for mechanical expansion of the device. Such expansion can advantageously permit for at least partial distraction of the superior endplate of the first vertebra relative to the superior endplate of the adjacent second vertebra. In some embodiments, an expandable implant comprises metal, bone, PEEK, carbon fiber, plastic, rubber and/or any other rigid, semi-rigid and/or non-pliable material. In some embodiments, such implants could be inserted into the intervertebral space and expanded using a mechanical actuation (e.g., screw or wire compression-distraction, screw-jack mechanism, another device, component or mechanism that can drive the cephalad component away from the caudal component to allow distraction of the disc space in a parallel or lordotic fashion, stackable wafers of a noncompressible material, inflatable balloon, or flowable graft/biologic implant that remains flowable or at least partially hardens or sets after a period of time or with actuation, etc.). In some embodiments, an implant placed into the intervertebral space could be linked by wire or other means to an electric current from battery or other source to allow stimulation of the implant and/or the graft material within the intervertebral space to allow for enhancement of fusion of the intervertebral space. 
     As noted above, according to some embodiments, a method of fusing a first vertebra to a second vertebra, wherein the second vertebra is immediately adjacent and above the first vertebra, comprises creating a passage from a posterior end of a pedicle of the first vertebra through a superior endplate of the first vertebra, such that the passage extends into an intervertebral space located generally between the first and second vertebrae. The method further comprises removing native tissue located within the intervertebral space by advancing a tissue removal tool through the passage and selectively moving said tissue removal tool within the intervertebral space, and delivering at least one of an implant and a grafting material through the passage, wherein said implant or grafting material is configured to promote fusion between the superior endplate of the first vertebra and an inferior endplate of the second vertebra.  FIGS. 27A to 30  schematically illustrate various devices, tools and/or methods  4000  associated with such embodiments. 
       FIG. 27A  illustrates an access device (e.g., an access cannula)  4010  that is configured to be passed through a transpedicular passage created to provide access to a targeted intervertebral space of a subject. As illustrated in  FIGS. 28 and 29 , a transpedicular passage (e.g., through which an access cannula  4010  is positioned) can be created through the skin S of a subject and through, at least partially, the pedicle P of a vertebral member V 2 . As also illustrated in  FIGS. 28 and 29 , the targeted intervertebral space IVS of the subject is located between above the vertebral member V 2  through which the transpedicular passage and cannula  4010  are located and below the immediately adjacent (e.g., above) vertebral member V 1 . 
     The various embodiments disclosed herein can be performed as a unilateral approach (e.g., along only a single lateral side of the subject&#39;s spine) or as a bilateral approach (e.g., along both lateral sides of the subject&#39;s spine). For simplicity and clarity, the schematic illustrations of  FIGS. 27A to 30  show a unilateral approach. 
     As discussed with reference to other embodiments herein, once a transpedicular passage is created in a vertebral member, the access device  4010  is positioned within that passage and access is provided to the targeted intervertebral space, discectomy and/or other preparatory procedures can be performed through the access device  4010 . For example, in some embodiments, one or more discectomy tools, regardless of whether or not specifically disclosed herein, can be advanced into and within the intervertebral space to remove native tissue and prepare the space for the subsequent steps. 
     With continued reference to  FIG. 27A , the access cannula or other access device  4010  can be linear or substantially linear to match or substantially match the corresponding transpedicular passage through which it will be passed. As shown, the cannula or other access device  4010  can include a central opening  4018  that extends along the entire length (e.g., from a proximal end  4012  to a distal end  4014 ). 
     As depicted in  FIGS. 27B and 27C , an implant tube assembly  4020  can be sized, shaped and otherwise configured to be passed through the opening  4018  of the access cannula or other device  4010 . The distal end  4024  of the implant tube assembly  4020  can comprise a main portion  4030  an expandable implant portion (e.g., a coiled implant portion, an inflatable implant portion, a sac, etc.)  4040 . The proximal end  4022  of the implant tube assembly  4020  can include a flared opening  4032 . However, in some arrangements, the proximal opening of the implant tube assembly does not have a flared shape, as desired or required. 
     In some embodiments, the implant tube assembly  4020  can be advanced through the access cannula  4010  in order to position the expandable implant portion  4040  located at the distal end of the implant tube assembly  4020  within a desired location of the targeted intervertebral space IVS, as illustrated in  FIG. 28 . Once the expandable implant portion  4040  has been properly positioned (e.g., along the desired or required location of the intervertebral space IVS). Next, graft material and/or other filling material can be directed into the cannulated opening of the implant tube assembly  4020  to at least partially fill and advantageously expand the expandable implant portion  4040 . As illustrated schematically in  FIG. 28 , a fill assembly  4050  can be used to selectively deliver the graft material and/or other filler material into the implant tube assembly  4020 , and eventually, in the expandable implant portion  4040 . In some embodiments, the fill assembly (e.g., graft fill assembly)  4050  includes a handle  4056  and a hand-operated trigger  4058  (e.g., or other mechanical feature or component) to assist with the movement of the graft material and/or other filler material into the implant tube assembly  4020 . In some embodiments, movement of the graft material and/or other filler material can be assisted using a manual, mechanical, electromechanical, pneumatic and/or other tool, device, feature, component and/or the like, as desired or required. 
     Next, in some arrangements, once the expandable implant portion  4040  has been filled to a desired extent, the expandable implant portion  4040  can be separated from the main portion  4030  of the implant tube assembly  4020 . The remaining tools and devices can be removed from the subject, including, for example, the implant tube assembly  4020  and the fill assembly  4050 . The access device or cannula  4010  can be removed, leaving the expanded interbody implant (e.g., the expandable implant portion  4040 ) that has been at least partially filled with graft and/or other filler material within the targeted intervertebral space IVS. Such an implant can promote fusion of the adjacent vertebral members V 1 , V 2  over time. 
     As illustrated schematically in  FIG. 30 , and discussed in greater detail above, fusion using such an implant can be supplemented and reinforced by using one or more additional fixation systems or technologies. For example, as shown, pedicle screws S 1 , S 2  inserted into each of the adjacent vertebral members V 1 , V 2  can be coupled to one another using a rod system R and/or any other type of fixation system (e.g., a posterior fixation system), as desired or required. 
     To assist in the description of the disclosed embodiments, words such as upward, upper, bottom, downward, lower, rear, front, vertical, horizontal, upstream, downstream have been used above to describe different embodiments and/or the accompanying figures. It will be appreciated, however, that the different embodiments, whether illustrated or not, can be located and oriented in a variety of desired positions. 
     Although the subject matter provided in this application has been disclosed in the context of certain specific embodiments and examples, it will be understood by those skilled in the art that the inventions disclosed in this application extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the subject matter disclosed herein and obvious modifications and equivalents thereof. In addition, while a number of variations of the inventions have been shown and described in detail, other modifications, which are within the scope of these inventions, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the inventions disclosed herein. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combine with or substituted for one another in order to form varying modes of the disclosed inventions. Thus, it is intended that the scope of the subject matter provided in the present application should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.