Patent Publication Number: US-2023137358-A1

Title: Expandable interbody implant and breakoff screw

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation in part of U.S. patent application Ser. No. 17/515,709, titled Expandable Implant and Corresponding Inserter, filed Nov. 1, 2021, the entire disclosure of which is incorporated herein by reference. This application also incorporates by reference the entire contents of: U.S. patent application Ser. No. 17/356,950, titled EXPANDABLE INTERBODY IMPLANT, filed Jun. 24, 2021; U.S. application Ser. No. 17/307,578, titled EXTERNALLY DRIVEN EXPANDABLE INTERBODY AND RELATED METHODS, and filed May 5, 2021; U.S. Pat. No. 11,096,796, titled Interbody spinal implant having a roughened surface topography on one or more internal surfaces, and filed on Mar., 4, 2013; and U.S. Pat. No. 10,821,000, titled Titanium implant surfaces free from alpha case and with enhanced osteoinduction, and filed Jun. 29, 2017. 
    
    
     FIELD 
     In one aspect, the present technology is generally related to an externally driven expandable interbody implant for use in a medical procedure related to the spine. In some embodiments, disclosed implants may be used in an anterior cervical discectomy and fusion (ACDF) procedure although other uses in other areas of the spine or between two bones are also contemplated. In another aspect, the present technology is generally related to a breakoff screw having a recessed fracture surface that may be used with various medical implants including an interbody implant. 
     BACKGROUND 
     Mechanically operated interbody implants may be used to align and/or realign a patient&#39;s spine during a medical procedure and/or for purposes of fusion, degenerative tissue and/or trauma/repair procedures. Conventional implants designed for the Thoracic and Lumbar region of the spine often include top and bottom endplates and a mechanical means to separate the top and bottom endplates. The mechanical mechanisms to separate the top and bottom endplates are often cumbersome and require a large footprint that is often unsuitable, for example, for ACDF type surgeries of the cervical portion of the spine. Additionally, conventional breakoff screws may lack a recessed fracture surface and sharp ends of an exposed fracture surface may damage or cut adjacent soft tissues of a patient. 
     SUMMARY 
     The techniques of this disclosure generally relate to an expandable interbody implant including a superior endplate and an inferior endplate hingedly coupled and which may further include a locking element to secure the inferior endplate and superior endplate in a particular configuration, for example. The superior and inferior endplates may be moved in a multitude of expanded and/or lordosed or kyphosed or otherwise angled configurations via an external inserter for example. In various embodiments, a locking screw may be a breakoff type screw. In various embodiments at least one breakoff tang on the implant may be used to for gripping of the implant to insert it into a disc space and afterwards the breakoff tang may be broken off and removed. Additionally, in various embodiments the locking screw may be used to grip the implant and insert it into a disc space. Additionally, in various embodiments female recesses, rather than tangs, may be used for gripping of the implant and inserting the implant into a disc space. 
     In one aspect, the present disclosure provides for an expandable implant movable between a contracted position and an expanded position, for example. The expandable implant may include an expandable body extending from a proximal end to a distal end in a proximal-to-distal direction and extending from a first lateral side to a second lateral side in a widthwise direction, for example. In various embodiments, the expandable body may be defined by a superior endplate and an inferior endplate that are hingedly connected, for example. In various embodiments, the superior endplate includes a first core having a distal engagement surface and the inferior endplate includes a second core having a proximal engagement surface and a threaded screw aperture, for example. In various embodiments, disclosed implants may include a threaded breakoff screw having a fracture surface that is disposed in the threaded screw aperture and movable between a locked position and an unlocked position, for example. In various embodiments, when in the locked position, the breakoff screw urges the distal engagement surface of the first core into direct contact with the proximal engagement surface of the second core, for example. 
     In another aspect, the disclosure provides for a breakoff screw, including an elongate body extending in a proximal to distal direction along a longitudinal axis, for example. The elongate body may be defined by a proximal portion and a distal portion separated therebetween by a necked down portion forming a recessed fracture surface, for example. In various embodiments, the proximal portion may include a first drive feature and a first flexible tang and a second flexible tang, for example. In various embodiments, the distal portion may include a second drive feature, engagement surface, and an external thread pattern, for example. In some embodiments, the recessed fracture surface is inset with respect to a proximal most surface of the second drive feature. 
     The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view of an expandable implant. 
         FIG.  2    is an alternate perspective view of an expandable implant. 
         FIG.  3    is a top down view of an expandable implant. 
         FIG.  4    is a side view of an expandable implant. 
         FIG.  5    is a rear perspective view of an expandable implant. 
         FIG.  6    is a perspective view of the interior of a superior endplate of an expandable implant. 
         FIG.  7    is a perspective view of the interior of an inferior endplate of an expandable implant. 
         FIG.  8    is a perspective exploded parts view of an expandable implant. 
         FIG.  9    an exploded parts view of an expandable implant from a side view perspective. 
         FIG.  10    is a perspective cross section view of an expandable implant. 
         FIG.  11    is a cross section view of an expandable implant. 
         FIG.  12    is a side view of a superior endplate for use with at least some expandable implant embodiments. 
         FIG.  13 A  is a perspective view of a first expandable implant. 
         FIG.  13 B  is a perspective view of a second expandable implant. 
         FIG.  14 A  is a perspective view of a third expandable implant. 
         FIG.  14 B  is a perspective view of a fourth expandable implant. 
         FIG.  15    is a perspective view of a fifth expandable implant. 
         FIG.  16    is a side view of an expandable implant in the expanded configuration. 
         FIG.  17    is a side view of an expandable implant showing a bone screw trajectory. 
         FIG.  18    is a front view of an expandable implant. 
         FIG.  19    is a front view of an enlarged area of  FIG.  18   . 
         FIG.  20    is a perspective view of an inserter for use with disclosed expandable implants. 
         FIG.  21    is a perspective view of an inserter for use with disclosed expandable implants shown in skeleton outlining for ease of understanding. 
         FIG.  22    is a perspective view of an inserter for use with disclosed expandable implants shown in skeleton outlining for ease of understanding. 
         FIG.  23 A  is a rear view of an inserter in a non-expanded position. 
         FIG.  23 B  is a rear view of an inserter in an expanded position. 
         FIG.  24    is an enlarged view of a distal end of an inserter in an expanded position coupled to an example expandable implant in a corresponding expanded position. 
         FIG.  25    is a perspective view of an expandable implant in an expanded configuration after a breakoff portion of a locking screw has been broken off 
         FIG.  26    is a perspective view of a surgical instrument for use with disclosed expandable implants. 
         FIG.  27    is a perspective view of a surgical instrument for use with disclosed expandable implants. 
         FIG.  28    is a perspective view of an expandable implant after the mounting tangs have been broken off 
         FIG.  29    is a reference drawing showing the human spine of which various disclosed implant embodiments may be installed in. 
         FIG.  30    is a reference drawing showing various planes and reference directions of which the various disclosed implant embodiments may move in or act in with respect to a patient. 
         FIG.  31    is a perspective view of a second implant embodiment. 
         FIG.  32    is a first perspective exploded parts view of the second implant embodiment. 
         FIG.  33    is a second perspective exploded parts view of the second implant embodiment. 
         FIG.  34    is a side exploded parts view of the second implant embodiment. 
         FIG.  35    is a first side view of a breakoff screw having a recessed fracture surface. 
         FIG.  36    is a second side view of a breakoff screw having a recessed fracture surface. 
         FIG.  37    is a cross section view of a breakoff screw having a recessed fracture surface. 
         FIG.  38    is a perspective view of a swaging fixture. 
         FIG.  39    is a cross section view of a swage mandrel and a distal end of a breakoff screw before the commencement of a swage process. 
         FIG.  40    is a cross section view showing a result of a swage process. 
         FIG.  41    is an enlarged view of region S-W of  FIG.  40   . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure relate generally, for example, to spinal stabilization systems, and more particularly, to surgical instruments for use with spinal stabilization systems. Embodiments of the devices and methods are described below with reference to the Figures. 
     The following discussion omits or only briefly describes certain components, features and functionality related to medical implants, installation tools, and associated surgical techniques, which are apparent to those of ordinary skill in the art. It is noted that various embodiments are described in detail with reference to the drawings, in which like reference numerals represent like parts and assemblies throughout the several views, where possible. Reference to various embodiments does not limit the scope of the claims appended hereto because the embodiments are examples of the inventive concepts described herein. Additionally, any example(s) set forth in this specification are intended to be non-limiting and set forth some of the many possible embodiments applicable to the appended claims. Further, particular features described herein can be used in combination with other described features in each of the various possible combinations and permutations unless the context or other statements clearly indicate otherwise. 
     Terms such as “same,” “equal,” “planar,” “coplanar,” “parallel,” “perpendicular,” etc. as used herein are intended to encompass a meaning of exactly the same while also including variations that may occur, for example, due to manufacturing processes. The term “substantially” may be used herein to emphasize this meaning, particularly when the described embodiment has the same or nearly the same functionality or characteristic, unless the context or other statements clearly indicate otherwise. 
     Referring to  FIGS.  1 - 43    generally, various embodiments and views of an expandable implant  100  are disclosed. The components of expandable implant  100  can be fabricated from biologically acceptable materials suitable for medical applications, including metals, synthetic polymers, ceramics and bone material and/or their composites. For example, the components, individually or collectively, can be fabricated from materials such as stainless steel alloys, commercially pure titanium, titanium alloys, Grade 5 titanium, super-elastic titanium alloys, cobalt-chrome alloys, superelastic metallic alloys (e.g., Nitinol, super elasto-plastic metals, such as GUM METAL™), ceramics and composites thereof such as calcium phosphate (e.g., SKELITE™), thermoplastics such as polyaryletherketone (PAEK) including polyetheretherketone (PEEK), polyetherketoneketone (PEKK) and polyetherketone (PEK), carbon-PEEK composites, PEEK-BaSO4 polymeric rubbers, polyethylene terephthalate (PET), fabric, silicone, polyurethane, silicone-polyurethane copolymers, polymeric rubbers, polyolefin rubbers, hydrogels, semi-rigid and rigid materials, elastomers, rubbers, thermoplastic elastomers, thermoset elastomers, elastomeric composites, rigid polymers including polyphenylene, polyamide, polyimide, polyetherimide, polyethylene, epoxy, bone material including autograft, allograft, xenograft or transgenic cortical and/or corticocancellous bone, and tissue growth or differentiation factors, partially resorbable materials, such as, for example, composites of metals and calcium-based ceramics, composites of PEEK and calcium based ceramics, composites of PEEK with resorbable polymers, totally resorbable materials, such as, for example, calcium based ceramics such as calcium phosphate, tri-calcium phosphate (TCP), hydroxyapatite (HA)-TCP, calcium sulfate, or other resorbable polymers such as polyaetide, polyglycolide, polytyrosine carbonate, polycaroplaetohe, polylactic acid or polylactide and their combinations. 
     In various embodiments, components may be coated with a ceramic, titanium, and/or other biocompatible material to provide surface texturing at (a) the macro scale, (b) the micro scale, and/or (c) the nano scale, for example. Similarly, components may undergo a subtractive manufacturing process providing for surface texturing configured to facilitate osseointegration and cellular attachment and osteoblast maturation. Example surface texturing of additive and subtractive manufacturing processes may comprise (a) macro-scale structural features having a maximum peak-to-valley height of about 40 microns to about 500 microns, (b) micro-scale structural features having a maximum peak-to-valley height of about 2 microns to about 40 microns, and/or (c) nano-scale structural features having a maximum peak-to-valley height of about 0.05 microns to about 5 microns. In various embodiments, the three types of structural features may be overlapping with one another, for example. Additionally, such surface texturing may be applied to any surface, e.g., both external exposed facing surfaces of components and internal non exposed surfaces of components. Further discussion regarding relevant surface texturing and coatings is described in, for example, U.S. Pat. No. 11,096,796, titled Interbody spinal implant having a roughened surface topography on one or more internal surfaces, and filed on Mar., 4, 2013—the entire disclosure of which is incorporated herein by reference in its entirety. Accordingly, it shall be understand that any of the described coating and texturing processes of U.S. Pat. No. 11,096,796, may be applied to any component of the various embodiments disclosed herein, e.g., the exposed surfaces and internal surfaces of endplates. Another example technique for manufacturing an orthopedic implant having surfaces with osteoinducting roughness features including micro-scale structures and nano-scale structures is disclosed in U.S. Pat. No. 10,821,000, the entire contents of which are incorporated herein by reference. Additionally, an example of a commercially available product may be the Adaptix™ Interbody System sold by Medtronic Spine and comprising a titanium cage made with Titan nanoLOCK™. 
     Referring generally to  FIGS.  1 - 5    various views of an expandable implant  100  in a collapsed position are illustrated.  FIGS.  1 - 2    are various perspective views of an expandable implant  100 .  FIG.  3    is a top down view of an expandable implant  100 . In the example embodiment, expandable implant  100  may include a proximal end  100 P, a distal end  100 D, and first and second lateral sides  100 L. Additionally, a pair of bone screw apertures  11 ,  21  may be positioned on the proximal end  100 P, for example. In various embodiments, bone screw apertures  11 ,  21  may comprise a corresponding bone screw retention mechanism  11   a,    21   a  (may also be referred to as an anti-backout locking mechanism). In the example embodiment, the bone screw retention mechanisms  11   a,    21   a,  comprise a flexible tang member having a hook portion at an end thereof that allows the flexible tang member to flex outward in a lateral direction away from the corresponding bone screw aperture  11 ,  21  during initial installation of the bone screw and to flex back inward towards the corresponding bone screw aperture  11 ,  21  to prevent a corresponding bone screw from backing out. For example, as the bone is installed in bone screw aperture  11 ,  21 , the bone screw retention mechanism  11   a,    21   a,  may flex outward as the underside of the head portion contacts inclined surface  11   c  (see  FIG.  19   ). 
     In various embodiments, and as illustrated in  FIGS.  1 - 2   , mounting tangs  19 ,  29  may extend in a proximal direction, for example. In various embodiments, implant  100  may be referred to as an externally driven expandable implant because an end user or surgeon may use a surgical tool to open and close implant  100 , e.g. expand implant  100 . For example, an external tool may adjust the lordotic angle of implant  100  as will be explained in detail with respect to  FIGS.  20 - 25   . Once implant  100  is expanded to an appropriate lordotic angle (also referred to as angle of inclination), an end user may fix the relative angle of the superior endplate  10  relative to the inferior endplate  20  by tightening locking screw  50 , for example. In some embodiments, superior endplate  10  may be referred to as a “cephalad” endplate and inferior endplate  20  may be referred to as a “caudal” endplate. 
     Locking screw  50  may also be used in other embodiments, such as fixation of posterior rods, fixation of pedicle screws, and other set screw constructs. Additionally, locking screw  50  may be referred to as a “breakoff screw” in some embodiments. 
     At least one advantage of relying on an external tool to adjust a lordotic angle of implant  100  may be the reduction of internal components within implant  100  relative to other forms of implants relying on various moving mechanisms and/or expansion mechanisms, for example. Accordingly, in various embodiments, implant  100  may have a relatively large void space in the interior thereof, which may facilitate a fusion process during an ACDF procedure. For example, implant  100  may have a relatively large internal volume  101  that is open through the superior endplate  10  and inferior endplate  20  which may be packed with bone graft material, for example. 
     As illustrated in  FIG.  3   , implant  100  may extend in a proximal-to-distal direction (also referred to as a longitudinal direction) from the proximal end  100 P to the distal end  100 D though axis P-D through the center of the implant  100 , for example. Implant  100  may extend in a widthwise direction (also referred to as lateral direction) from the first lateral side  100 L to the second lateral side  100 L through axis W-W through the center of the implant  100  and the center of locking screw  50 , for example. The axis P-D may be perpendicular and/or substantially perpendicular to the axis W-W. For example, the proximal-to-distal direction may be perpendicular to the widthwise direction. Additionally, a width of the implant may taper from a proximal end  100 P where it is widest towards a distal end  100 D where it is narrowest. 
       FIG.  4    is a side view of an expandable implant  100 . In the example illustration, it is shown that a superior endplate  10  is connected to an inferior endplate  20  such that the superior endplate may pivot about a hinge member  40 . In the example embodiment, hinge member  40  comprises an arcuate rail portion of inferior endplate  20  that extends in the widthwise direction, for example. In the example embodiment, hinge member  40  may be nested into a corresponding arcuate cavity of the superior endplate  10  such that superior endplate  10  may expand and/or otherwise rotate about hinge member  40 . Additionally, in various embodiments the superior endplate  10  and/or inferior endplate  20  may include various engagement elements  14  for engaging with an adjacent boney structure such as a vertebrae, for example. In the example embodiment, the engagement elements comprise a series of alternating rails and valleys therebetween that extend in the widthwise direction. However, claws, hooks, dimples, spikes, etc. are also contemplated as example engagement elements  14 . In some embodiments, an acid etching process may be utilized to form a roughened or textured surface to facilitate securing the implant between boney portions and/or suppressing expulsion of implant  100 . 
       FIG.  5    is a rear perspective view of an expandable implant  100 . In the example illustration it is shown that the distal end  100 D is narrower than the proximal end  100 P.  FIG.  6    is a perspective view of the interior of a superior endplate  10 . In the example illustration, it is shown that the distal end of superior endplate  10  includes an arcuate channel  12  of which the hinge member  40  may be disposed inside of The proximal end of superior endplate  10  may include a bone screw aperture cutout  21   b  to allow a relief area for a corresponding bone screw to be insert through bone screw aperture  21  of inferior endplate  20 , for example. Superior endplate  10  may also include a core  15  comprising an aperture  15   a  that extends from a proximal surface  15   p  thereof to a distal surface  15   d  thereof, for example. In various embodiments, aperture  15   a  may be referred to as a “slot” or “screw slot”. In some embodiments, core  15  may be referred to as a support frame and take a generally rectangular shape. In various embodiments, the distal surface  15   d  may be curved and generally face the distal end  100 D of implant  100 .  FIG.  7    is a perspective view of the interior of an inferior endplate  20 . In the example illustration, it is shown that the distal end of inferior endplate  20  includes a hinge member  40  in the form of an arcuate rail that may be disposed inside of the arcuate channel  12  of the superior endplate  10 , for example. The proximal end of inferior endplate  20  may include a bone screw aperture cutout  11   b  to allow a relief area for a corresponding bone screw to be insert through bone screw aperture  11  of superior endplate  10 , for example. Inferior endplate  20  may also include a core  25  comprising a threaded aperture  25   a  that extends from a proximal surface  25   p  thereof to a distal surface  25   d  thereof, for example. In some embodiments, core  25  may be referred to as a support frame and take a generally rectangular shape. In various embodiments, the superior endplate  10  and inferior endplate  20  may each be formed a unitary single piece, respectively. 
       FIG.  8    is a perspective exploded parts view and  FIG.  9    is an exploded parts view from a side view perspective of an expandable implant  100 . In the example embodiment, a locking screw  50  is illustrated. Locking screw  50  may include an external thread pattern  51  on an outside circumferential surface thereof, for example. The external thread pattern  51  of locking screw  50  may have a size and shape generally corresponding to the threaded aperture  25   a  of core  25  of inferior endplate  20 , for example. In various embodiments, an engagement surface  54  may be disposed adjacent and proximal of external thread pattern  51 . In the example embodiment, engagement surface  54  is shaped like a washer and is directly connected to locking screw  50 . However, in other embodiments, engagement surface  54  may be a washer or separated element, for example. In some embodiments, engagement surface  54  may be conically shaped. Engagement surface  54  may include a relatively planar and/or flat distal surface and/or proximal surface. In various embodiments, a proximal end of set screw  50  may include an aperture having an internal threaded surface  52 . For example, a cylindrical shaped proximal end may include an aperture having a thread pattern disposed on an internal circumferential surface of the cylindrical shaped proximal end. In the example embodiment, a first drive feature  53   a  and a second drive feature  53   b  may be disposed adjacent to and distally with respect to a proximal most end of set screw  50 . Additionally, first and second drive features  53   a,    53   b  may be disposed proximally with respect to engagement surface  54 . In the example embodiment, drive features  53   a,    53   b  take a hexalobular shape, although various other shapes such as hexagonal, polygonal, Torx, etc. are also contemplated. In some embodiments, a surgical drive tool having a corresponding socket may be coupled to drive features  53   a,    53   b  to cause rotation of locking screw  50 . Similarly, in some alternative embodiments, a drive tool with a protruding threaded member having a thread pattern with a corresponding size and shape to internal threaded surface  52  may also cause rotation of set screw  50 . 
     As seen best in  FIG.  9   , set screw  50  may also include a breakoff location  55 , for example. In the example embodiment, breakoff location  55  is disposed directly between drive features  53   a,    53   b  and is designed to shear off when a sufficient rotational force is applied to a proximal end of set screw  50  while a distal end of set screw  50  is stationary, e.g., when set screw  50  is secured in a locked position and a continued rotational force (torque) is applied to the proximal end of set screw  50  the drive feature  53   a  and cylindrical end having the internal threaded surface  52  may breakoff. As also seen best in  FIG.  9   , the inferior endplate  20  may include a first relief  40   a  and a second relief  40   b  on opposite sides of hinge member  40 . The first relief  40   a  may have a size and shape corresponding to a size and shape of a first portion  12   a  of superior endplate  10  and the second relief  40   b  may have a size and shape corresponding to a size and shape of a second portion  12   b  of superior endplate  10 , for example. In various embodiments, portions  12   a,    12   b  may comprise a hook shape, outdent, and/or protrusion, for example. In the example embodiment, portions  12   a,    12   b  may be disposed on opposite sides of channel  12  and cup hinge member  40  such that the superior endplate  10  and inferior endplate  20  may rotate relative to one another without becoming uncoupled. 
       FIG.  10    is a perspective cross section view and  FIG.  11    is a cross section view of expandable implant  100 . In the example embodiment, the superior endplate  10  and inferior endplate  20  are coupled together by hinge member  40 , and core  25  may be positioned behind of core  15 , e.g., core  25  may be positioned distally with respect to core  15 . Additionally, the outside external thread pattern  51  of locking screw  50  may engage with the threaded aperture  25   a  of the core  25  and extend through aperture  15   a  of core  15 . In this way, when locking screw  50  is rotated, the distal surface  15   d  of core  15  may engage with the proximal surface  25   p  of core  25 . For example, by tightening locking screw  50  the engagement surface  54  of locking screw  50  pushes against the proximal surface  15   p  of core  15  thereby bringing the superior endplate  10  and inferior endplate  20  into frictional engagement. 
       FIG.  12    is a side view of a superior endplate  10  for use with at least some expandable implant  100  embodiments. In the example embodiment, superior endplate  10  may include an arcuate channel  12  of which the hinge member  40  may be disposed inside of In various embodiments, arcuate channel  12  may be defined by a first circle having a center point at P 1  and/or a segment of the circle having the center point at P 1 . The center point P 1  may define an axis of rotation that superior endplate  10  may rotate and/or pivot with respect to inferior endplate  20 . For example, superior endplate  10  may be hingedly coupled to hinge member  40  as explained above and rotatable about an axis of rotation defined by center point P 1 , for example. Additionally, in various embodiments a distal surface  15   d  of core  15  may be a curved surface defined (in part or in total) by a second circle having a center point at P 1  and a radius R 1 . The proximal surface  15   p  of core  15  may also be a curved surface defined (in part or in total) by a segment of a circle having a radius R 2  and a center point P 2 . In the example embodiment, P 2  is located a distance D 1  above point P 1  and radius R 2  is greater than radius R 1 . Additionally, the proximal surface  15   p  of core  15  is offset a distance D 2  from the proximal most face of the superior endplate  10 . In the example embodiment, center point P 2  is vertically above center point P 1  however, in other embodiments, center point P 2  may be offset by a greater amount or even a lesser amount than illustrated. In some examples, P 2  may not be aligned vertically above P 1 . In various embodiments, R 1  may be about 7-9 mm+/−about 1 mm and R 2  may be about 8-10 mm+/−about 1 mm although these numbers may be modified in some embodiments having a larger or smaller footprint. In various embodiments D 1  is about 0.25 mm to about 1.0 mm and D 2  is about 0.25 mm to about 1.25 mm. In at least one embodiment, D 1  is about 0.75 mm and D 2  is about 0.8 mm and R 2  is about 9.2 mm. 
     The above explained geometrical relationship between the offset center points P 1  and P 2  and R 1  and R 2  may have several advantages in terms of operability and functionality. At least one advantage is that the superior endplate  10  may have a natural tendency to apply a force against the engagement surface  54  of locking screw  50  such that locking screw  50  may function similar to a wedge preventing implant  100  from fully collapsing. Another advantage is that a biasing force may be applied that naturally urges the superior endplate  10  and inferior endplate  20  into an expanded position which may assist with expanding the implant  100  when positioned between a superior vertebrae and an inferior vertebrae, for example. For example still, an end user such as a surgeon may expand implant  100  and the offset arrangement explained above may facilitate the function of keeping implant  100  lordosed at the chosen angle. 
       FIG.  13 A  is a perspective view of a first expandable implant,  FIG.  13 B  is a perspective view of a second expandable implant,  FIG.  14 A  is a perspective view of a third expandable implant,  FIG.  14 B  is a perspective view of a fourth expandable implant, and  FIG.  15    is a perspective view of a fifth expandable implant. In the series of illustrations it is shown that various embodiments in accordance with the principles of this disclosure may be variously sized depending on the particular location in a human body and the particular patient specific human anatomy. For example,  FIG.  13 A  illustrates a first expandable implant  100  having a first height H 1  or thickness between the superior endplate  10  and inferior endplate  20 ,  FIG.  13 B  illustrates a second expandable implant  100  having a second height H 2  or thickness,  FIG.  14 A  illustrates a third expandable implant  100  having a third height H 3  or thickness,  FIG.  14 B  illustrates a fourth expandable implant  100  having a fourth height H 4  or thickness, and  FIG.  15    illustrates a fifth expandable implant  100  having a fifth height H 5  or thickness. In at least some embodiments, H 1  may be about 5 mm, H 2  may be about 6 mm, H 3  may be about 7 mm, H 4  may be about 8 mm, H 5  may about 9 mm, for example. In various embodiments, an angle of inclination between the superior endplate  10  and inferior endplate  20  may be about 4 degrees to about 15 degrees in an expanded configuration, e.g., an angled and/or inclined configuration. 
       FIG.  16    is a side view of an expandable implant  100  in the expanded configuration. In an expanded position, a distance D 3  between the superior endplate  10  and inferior endplate  20  at the proximal end  100 P may be relatively greater than in the closed configuration, for example. Additionally, an angle of inclination α may be relatively greater in an expanded position than in the closed configuration, for example. In this embodiment, implant  100  may have a height H 1  corresponding to  FIG.  13 A  and be about 5 mm in a closed configuration. In the illustrated expanded configuration of  FIG.  16   , D 3  may be about 8 mm to 9 mm and α may be about 10 degrees to about 20 degrees. In at least one embodiment, D 3  may be 8 mm in a fully expanded position and α may be about 15 degrees, for example. 
       FIG.  17    is a side view of an expandable implant  100  showing a bone screw trajectory  99 . In the example embodiment, it is shown that a centered bone screw trajectory  99  of bone screw  97  is at an angle β with respect to a plane  98  that crosses through a center of the implant from a first lateral side to a second lateral side, for example. Additionally, the bone screw trajectory  99  may be varied+/−by a degree γ, for example. In various embodiments, β may be about 30 degrees to about 50 degrees and γ may be about 2 degrees to about 10 degrees. In the example embodiment, β may be about 40 degrees and γ may be about 5 degrees. 
       FIG.  18    is a front view of an expandable implant showing an area A 1  and  FIG.  19    is a front view of an enlarged area A 1  of  FIG.  18   . In the example embodiment, bone screw  97  is in a position extending through bone screw aperture  11  where it cannot backout due to bone screw retention mechanism  11   a.  The bone screw retention mechanism  11   a  includes an inclined surface  11   c  such that when bone screw  97  is being installed, an underside of the head portion of bone screw  97  directly contacts the inclined surface  11   c  thereby pushing the bone screw retention mechanism  11   a  laterally outward and away from bone screw aperture  11 , for example. Thereafter, when bone screw  97  is installed and the head portion of bone screw  97  is beneath inclined surface  11   c  the bone screw retention mechanism may flex back towards bone screw aperture  11  such that it will prevent bone screw  97  from backing out, e.g., a blocking surface of bone screw retention mechanism  11   a  may contact an upper surface of the head portion of bone screw  97 . In the example embodiment, bone screw retention mechanism  11   a  comprises flexible arm (or spring tab) having an inclined surface  11   c  (or ramp) that is disposed on a lateral end of implant  100  adjacent bone screw aperture  11 . 
     Referring generally to  FIGS.  20 - 24    an inserter  200  for use with disclosed expandable implants  100  is illustrated. Inserter  200  may extend in a longitudinal direction from a proximal end  200   p  to a distal end  200   d,  for example. Inserter  200  may include a pair of handles  230 , a handle lock  202 , and mounting arms  210  for securely coupling to mounting tangs  19 ,  29  of implant  100 , for example. Inserter  200  may further include a tightening knob  211  that is connected to a drive shaft  220  having a drive end  221 . Drive end  221  may have a size and shape generally corresponding to a size and shape of the various drive features of locking screw  50 , for example the internal threaded surface  52 , first drive feature  53   a,  and/or second drive feature  53   b.  In the example embodiment shown in  FIG.  24   , drive end  221  includes an end portion having an outside threaded surface with a corresponding size and shape to the internal threaded surface  52  of locking screw  50 . In various embodiments, tightening knob  211  may rotate drive shaft  220  and drive end  221  to engage drive end  221  with locking screw  50  and pull implant  100  towards inserter tool  200  such that mounting tangs  19 ,  29  are securely nested within corresponding channels of mounting arms  210 . Additionally, an end user may rotate inserter  200  thereby translating a rotational force through drive end  221  to locking screw  50 , e.g., via first drive feature  53   a,  and/or second drive feature  53   b.    
     As seen best in  FIGS.  23 A and  23 B , inserter  200  may include a pair of handles  230 , a stationary arm  252 , a primary pivoting arm  250 , and a secondary pivoting arm  251 . For example, to expand implant  100  an end user may toggle handle lock  202  to an unlocked position and push down on thumb indentation  231  of the handle  230  that is connected to the primary pivoting arm  250  and secondary pivoting arm  251 . In doing so, primary pivoting arm  250  may pivot with respect to medial pivot point  240  and secondary pivoting arm  251  may pivot with respect to distal pivot point  245 , for example. The path of travel of secondary pivoting arm  251  may lift up on the corresponding mounting tang  19  or  29  and cause the superior endplate  10  and inferior endplate  20  to separate from one another at the proximal end, for example. In doing so, an end user can lordose implant  100  to a desired angle. For example, as seen best in  FIG.  24   , secondary pivoting arm  251  has lifted up on mounting tang  19 , which is nested in a corresponding channel of mounting arm  210 . 
     Once implant  100  is lordosed to a desired configuration, an end user may rotate drive shaft  220  and drive end  221  to tighten locking screw  50  as explained previously. After locking screw  50  is relatively tight, the end user may continue to apply a rotational force to locking screw  50  until a proximal portion comprising the cylindrical part having an internal threaded surface  52 , and the first drive feature  53   a  breaks off at breakoff location  55 . For example, once locking screw  50  is tightened to a designed torque, the locking screw  50  may shear off as explained previously. At least one advantage of utilizing the locking screw  50 , is that it may prevent over tightening which can cause deformation to implant  100 . As shown in  FIG.  25   , implant  100  has been expanded to a desired position and/or lordotic angle. Additionally, locking screw  50  has locked the relative position of the superior endplate  10  with respect to the inferior endplate  20  and the proximal portion of locking screw  50  has been broken off as explained above. 
       FIGS.  26  and  27    are various views of a surgical instrument  300  for use with disclosed expandable implants  100 . In some embodiments, surgical instrument  300  may be referred to as a breakoff instrument and may be used to breakoff the mounting tangs  19 ,  29  of implant  100 . In the example embodiment, surgical instrument  300  comprises a first instrument  310  and a second instrument  320 . First instrument  310  may extend in a longitudinal direction from handle  312  towards gripping end  311 . Similarly, second instrument  320  may extend in a longitudinal direction from handle  322  to gripping end  321 . Gripping ends  311 ,  321  may comprise a channel having a size and shape generally corresponding to mounting tangs  19 ,  29 . For example, as seen best in  FIG.  27   , the mounting tangs  19 ,  29  may be insert inside of the corresponding channels of gripping ends  311 ,  321 . After the mounting tangs  19 ,  29  are nested within gripping ends  311 ,  321  an end user may push laterally outward and/or inward against handles  312 ,  322  to breakoff the corresponding mounting tang  19 ,  29 . For example, as shown in  FIG.  28    expandable implant  100  is in an expanded and lordosed configuration and the proximal portion of locking screw  50  and tangs  19 ,  29  have been broken off. 
       FIG.  29    is a reference drawing showing the human spine of which various disclosed implant embodiments may be installed in.  FIG.  30    is a reference drawing showing various planes and reference directions of which the various disclosed implant embodiments may move in or act in with reference to a patient  1 . 
     Referring generally to  FIGS.  31 - 37    a second implant  400  embodiment is disclosed. Implant  400  may include the same, similar, and/or substantially the same components and functionality as explained above with respect to implant  100 . Accordingly, duplicative description will be omitted. It shall be understood that various components and functionality of implant  100  are readily combinable with implant  400  and vice versa unless the context clearly indicates otherwise. 
       FIG.  31    is a perspective view of a second implant  400  embodiment. In this embodiment, implant  400  extends in a proximal-to-distal direction between a proximal end  400 P and a distal end  400 D and extends in a width-wise direction between a first lateral end  400 L and a second lateral end  400 L. Additionally, implant  400  includes a superior endplate  410  and an inferior endplate  420  having substantially similar features and functionality as explained above with respect to superior endplate  10  and inferior endplate  20  of implant  100 , for example. However, in this embodiment, superior endplate  410  may include a first griping protrusion  419  extending in a proximal direction from the proximal end  400 P of the superior endplate  410 . Similarly, inferior endplate  420  may include a second griping protrusion  429  extending in a proximal direction from the proximal end  400 P of the inferior endplate  420 . In this embodiment, a size and shape of first gripping protrusion  419  is substantially the same as a size and shape of the second gripping protrusion  429 . However, in other embodiments the first and second gripping protrusions  419 ,  429  may be differently sized and shaped. In this embodiment, and in the closed position, each gripping protrusion  419 ,  429  is disposed at approximately the same distance from an axis of rotation of breakoff set screw  450 . In this embodiment, gripping protrusions  419 ,  429  may replace the need for the tangs  19 ,  29  of implant  100 , for example. However, the concepts of utilizing breakoff tangs  19 ,  29  and gripping protrusions  419 ,  429  are not necessarily mutually exclusive and attributes of one may be combined and/or modified in view of the other. 
     In various embodiments, gripping protrusions  419 ,  429  may include various types of contouring to facilitate grasping of gripping protrusions  419 ,  429  with a corresponding inserter, for example surface indentations, surface outdents, channeling, etc. In the example embodiment, gripping protrusion  419  comprises a superior gripping surface  419 A including an indented portion and an outdented chamfered portion at a proximal most end thereof, for example. Additionally, gripping protrusion  419  comprises an inferior gripping surface  419 B including an indented portion and an outdented chamfered portion at a proximal most end thereof, for example. Likewise, gripping protrusion  429  comprises a superior gripping surface  429 A including an indented portion and an outdented chamfered portion at a proximal most end thereof, for example. Additionally, gripping protrusion  429  comprises an inferior gripping surface  429 B including an indented portion and an outdented chamfered portion at a proximal most end thereof, for example. In this way, gripping protrusions  419  and  429  are shaped like dovetails and a corresponding inserter tool may comprise a corresponding shaped dovetail groove which may grasp onto and/or slip over gripping protrusions  419  and  429  (not illustrated). 
     Referring generally to  FIGS.  32 ,  33 , and  34    various exploded parts views of implant  400  are illustrated.  FIG.  32    is a first perspective exploded parts view of implant  400 ,  FIG.  33    is a second perspective exploded parts view of implant  400 , and  FIG.  34    is a side exploded parts view of implant  400 . In the example embodiment, the superior and inferior endplates  410 ,  420  of implant  400  may be hingedly coupled together by hinge member  440  and arcuate channel  412  having similar attributes as explained above with respect to hinge member  40  and channel  12  of implant  100 , for example. Additionally, superior endplate  410  may also include a core  415  having an aperture  415 A and inferior endplate  420  may include a core  425  having a threaded aperture  425 A having similar attributes to core  15  and core  25  as explained above with respect to implant  100 , for example. In the example embodiment, implant  400  utilizes a breakoff screw  450  for locking of a position of the superior and inferior endplate  410 ,  420 . Breakoff screw  450  may include an external thread pattern  451  on an outside circumferential surface thereof, for example. The external thread pattern  451  of breakoff screw  450  may have a size and shape generally corresponding to the threaded aperture  425   a  of core  425  of the inferior endplate  420 , for example. In various embodiments, an engagement surface  454  may be disposed adjacent and proximal of external thread pattern  451 . In the example embodiment, engagement surface  454  is shaped like a washer and is directly connected to breakoff screw  450 . However, in other embodiments, engagement surface  454  may be a washer or separated element, for example. In some embodiments, engagement surface  454  may be conically shaped. In the example embodiment, engagement surface  454  may include a relatively planar and/or flat distal surface and/or proximal surface. 
     In various embodiments, a proximal end of breakoff screw  450  may include a first flexible tang  452 A and a second flexible tang  452 B defining a discontinuous cylindrical shaped aperture  452  therebetween. Additionally, the first flexible tang  452 A and second flexible tang  452 B may each include an outdent at a proximal end thereof that is shaped like a segment of an annular ring. In the example embodiment, the first flexible tang  452 A may flex inward towards the second flexible tang  452 B under loading and vice versa due to the gap between them. At least one advantage of this configuration is that it may facilitate securing breakoff screw  450  to a corresponding drive tool (not illustrated) and the retention of the broken off part. For example, a drive tool may comprise a drive end having a female cavity with a corresponding size and shape to the drive features  453 A,  453 B. In various embodiments, the cavity may include a pair of indentations corresponding in size and shape to the outdents of flexible tangs  452 A and  452 B, for example. In use, an end user may align the flexible tangs  452 A,  452 B with the cavity, push down against the flexible tangs  452 A,  452 B which may cause them to flex inward towards each other such that they may slide within the cavity until the outdents of flexible tangs  45 A and  452 B are seated within the corresponding indents of the drive tool. Thereafter, an end user may continue to rotate and or tighten breakoff screw  450 . In this way, after a proximal portion of breakoff screw  450  is broken off it may remain retained by the inserter due to the flexible tangs  452 A and  452 B being seated within the corresponding indents. 
     In some embodiments, aperture  452  may be understood as a cylindrical protrusion extending in a proximal direction and having a first slit and a second slit extending along the length thereof such that the cyldrical protrusion is compressible. In the example embodiment, a first drive feature  453 A and a second drive feature  453 B may be disposed adjacent to and distally with respect to a proximal most end of breakoff screw  450 . Additionally, first and second drive features  453 A,  453 B may be disposed proximally with respect to engagement surface  454 . In various embodiments, a breakoff location may be positioned between and/or adjacent to drive features  453 A,  453 B, which will be explained in further detail below. In the example embodiment, drive features  453 A,  453 B take a hexalobular shape, although various other shapes such as hexaganol, polygonal, torx, etc. are also contemplated. In some embodiments, a surgical drive tool having a corresponding socket may be coupled to drive features  453 A and/or  453 B to cause rotation of breakoff screw  450 . Similarly as explained above with respect to locking screw  50 , once breakoff screw  450  has been sufficiently tightened a proximal portion may breakoff and/or shear off while the distal portion may remain coupled to implant  400  locking a relative orientation of superior endplate  410  and inferior endplate  420  in place. 
     As seen best in  FIGS.  35 - 37   , breakoff screw  450  may extend in a longitudinal direction along a longitudinal axis L-A that is coaxially aligned with breakoff screw  450 .  FIG.  35    is a first side view of breakoff screw  450  in which the superior surface  452 A and inferior surface  452 B of discontinuous aperture  452  are visible.  FIG.  36    is a second side view of a breakoff screw  450  that is rotated about 90 degrees with respect to  FIG.  35    in which only the superior surface  452 A is visible. With reference to  FIG.  37   , in various embodiments, breakoff location  455  may comprise a recessed fracture surface F-S that is inset with respect to a leading edge (proximal most edge) of drive feature  453 A. At least one advantage of the recessed fracture surface may be that delicate tissue is prevented and/or suppressed from coming into contact with relatively sharp ends of the fracture surface. In the example illustration, a relative location of the recessed fracture surface is represented by dashed lines F-S. In the example embodiment, breakoff location  455  may be considered as the boundary between a proximal portion  450 A and a distal portion  450 B of breakoff screw  450 , for example. In this embodiment, the boundary between drive features  453 A and  453 B comprises a necked down portion  458  extending from a distal end of drive feature  453 A to an inset portion of drive feature  453 B that is inset with respect to an outermost and/or proximal most surface of drive feature  453 B thereby defining a portion of breakoff set screw  450  having a minimum cross sectional diameter. Accordingly, when breakoff screw  450  is sufficiently tightened within threaded aperture  425 A of core  425  such that the breakoff location  455  experiences a sufficient torque the proximal portion  450 A may breakoff from the distal portion  450 B. For example, when a sufficient rotational force is applied to the proximal end of breakoff screw  450  while a distal end of breakoff screw  450  is stationary, i.e., when breakoff screw  450  is secured in a locked position and a continued rotational force (torque) is applied to the proximal end of breakoff screw  450  the drive feature  453   a  and cylindrical end having the discontinuous aperture  452  may breakoff. For further explanation in the similar context of implant  100 , see  FIGS.  10  and  11    and the corresponding discussion thereof. 
     Referring to  FIGS.  38 - 42    an example swaging process is performed to a distal most end of breakoff screw  450 .  FIG.  38    is a perspective view of a swaging fixture  500 , and  FIG.  39    is a cross section view of a swage mandrel and a distal end  450 D of a breakoff screw  450  before the commencement of a swage process.  FIG.  40    is a cross section view showing a result of a swage process, and  FIG.  41    is an enlarged view of region S-W of  FIG.  40   . In the example embodiment, swaging fixture  500  comprises a swaging ram  501  and a swaging mandrel  503  that are supported by the base of the apparatus. The swaging mandrel  503  may include an outdent that corresponds to and is slightly larger than the distal most indent  498  of breakoff screw  450 , for example. As seen in region S-W of  FIG.  40   , when swaging mandrel  503  is advanced into the distal most indent  498  a flared out portion  499  (swaged portion) is formed at a distal most end of breakoff screw  450 . An example advantage of a swaged end may be that it facilitates retention of the breakoff screw  450  such that it serves as a stopping structure preventing breakoff screw  450  from backing out of implant  100 . 
     It shall be understood that although breakoff screw  450  is explained concurrently with implant  400  and in the context of an intervertebral implant, the concepts of breakoff screw  450  may be applied to other embodiments used for alternate purposes, for example for use in a pedicle screw to insert in a tulip to tighten down a rod. It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. For example, features, functionality, and components from one embodiment may be combined with another embodiment and vice versa unless the context clearly indicates otherwise. Similarly, features, functionality, and components may be omitted unless the context clearly indicates otherwise. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). 
     Unless otherwise specifically defined herein, all terms are to be given their broadest possible interpretation including meanings implied from the specification as well as meanings understood by those skilled in the art and/or as defined in dictionaries, treatises, etc. It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless otherwise specified, and that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.