Patent Publication Number: US-9402741-B1

Title: Intervertebral implant having mechanical securement

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 14/636,305 filed on Mar. 3, 2015, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     The present invention relates to intervertebral implants for implantation between vertebral bodies. 
     Intervertebral implants are placed between vertebral bodies to replace degenerated intervertebral discs. They can be used as an alternative to spinal fusion to reduce pain in the neck and back while still allowing motion in the spine. Many intervertebral implants are designed to be fit between vertebral bodies but are not easily removable. Removal often involves destruction of the implant, so it may not be reused if removed from the spine. It would be desirable for an intervertebral implant to allow easy removal from the spine and for the implant to be reusable once removed. 
     Thus, there is a need for improvement in this field. 
     SUMMARY 
     The claims, and only the claims, recite the invention. In summary, it may include an intervertebral implant for implantation between an upper vertebral body and a lower vertebral body. The implant includes a body portion having a top side for contact with the upper vertebral body, a bottom side for contact with the lower vertebral body, and an anterior side between the top and bottom sides. The implant also includes a plate that is removably attachable to the body portion. The plate includes a top side for contact with the upper vertebral body, a bottom side for contact with the lower vertebral body, and a posterior side and an anterior side between the top and bottom sides. The plate defines in space a Z-axis generally in a cranial-caudal orientation therethrough and a Y-axis perpendicular to the Z-axis and passing through the anterior side. 
     The implant includes a first pathway through the plate and a first arcuate anchor movable in an arcuate path through the first pathway to penetrate into the upper vertebral body. It also includes a second pathway through the plate and a second arcuate anchor movable in an arcuate path through the second pathway to penetrate into the lower vertebral body. 
     The implant may include a locking member that is selectively movable between an open position and a closed position in a movement path that is generally transverse to the Y-axis. When the locking member is moved to the closed position it is located anteriorly of the first arcuate anchor and the second arcuate anchor, blocking the withdrawal of the first and second arcuate anchor from the anterior side of the plate. The locking member is selectively movable along a generally transverse movement path from the closed position to the open position to allow withdrawal of the first arcuate anchor and the second arcuate anchor from the anterior side of the plate to facilitate removal of the implant from between the upper and lower vertebral bodies. 
     Further forms, objects, features, aspects, benefits, advantages, and embodiments of the present invention will become apparent from a detailed description and drawings provided herewith. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view (see cut line  1 - 1  in  FIG. 3B ) of an intervertebral implant for implantation between an upper vertebral body and a lower vertebral body. 
         FIG. 2  is a partial top plan view of the body portion of  FIG. 1  showing an opening used for removal. 
         FIG. 3A  is a perspective view of an intervertebral implant including a locking member comprising a gate. 
         FIG. 3B  is a front view of the intervertebral implant of  FIG. 3A  configured in an unlocked position. 
         FIG. 3C  is a front view of the intervertebral implant of  FIG. 3A  with the locking member configured in a locked position. 
         FIG. 3D  is a top plan view of the intervertebral implant of  FIG. 3B . 
         FIG. 4A  is a front view of an intervertebral implant including a locking member comprising a cam configured in an unlocked position. 
         FIG. 4B  is a front view of the intervertebral implant of  FIG. 4A  with the locking member configured in a locked position. 
         FIG. 4C  is a top plan view of the intervertebral implant of  FIG. 4A . 
         FIG. 5A  is a front view of an intervertebral implant including a locking member comprising a lateral slide configured in an unlocked position. 
         FIG. 5B  is a front view of the intervertebral implant of  FIG. 5A  with the locking member configured in a locked position. 
         FIG. 5C  is a top plan view of the intervertebral implant of  FIG. 5A . 
         FIG. 6  is a side view of a slap hammer with a removal tool feature. 
         FIG. 7  is a cross-sectional view of an intervertebral implant for implantation between an upper vertebral body and a lower vertebral body. 
         FIG. 8  is a perspective view of a body portion of the intervertebral implant of  FIG. 7 . 
         FIG. 9  is a side cross-sectional view of a plate of the intervertebral implant of  FIG. 7 . 
         FIG. 10  is a perspective view of the intervertebral implant of  FIG. 7  including a locking member comprising a gate. 
     
    
    
     DESCRIPTION OF THE SELECTED EMBODIMENTS 
     For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. One embodiment of the invention is shown in great detail, although it will be apparent to those skilled in the relevant art that some features that are not relevant to the present invention may not be shown for the sake of clarity. 
     With reference to the drawing Figures, for example  FIGS. 1-5C , an intervertebral implant  100  for implantation between an upper vertebral body  105  and a lower vertebral body  110  is shown. The intervertebral implant  100  includes a body portion  120  having a top side  122  for contact with the upper vertebral body  105  and a bottom side  124  for contact with the lower vertebral body  110 . The intervertebral implant  100  also includes an anterior side  126  between the top and bottom sides  122 ,  124 . The body portion  120  defines, in space, a Z-axis generally in a cranial-caudal orientation therethrough and a Y-axis perpendicular to the Z-axis and passing through the anterior side  126 . 
     A first pathway  130  extends through the body portion  120  from the anterior side  126  to the top side  122  of the body portion. A first arcuate anchor  135  is movable in an arcuate path through the first pathway  130  to penetrate into the upper vertebral body  105 . 
     A second pathway  140  extends through the body portion  120  from the anterior side  126  to the bottom side  124  of the body portion  120 . A second arcuate anchor  145  is movable in an arcuate path through the second pathway  140  to penetrate into the lower vertebral body  110 . 
     One or more locking member  155 ,  160 ,  165  is selectively movable between an open position and a closed position in a movement path that is generally transverse to the Y-axis. Upon transverse movement to the closed position, the locking member is located anteriorly of the first arcuate anchor  135  and the second arcuate anchor  145 . The locking member blocks the withdrawal of the first arcuate anchor  135  and the second arcuate anchor  145  from the anterior side  126  of the body portion  120 . 
     The locking member is selectively movable along the generally transverse movement path from the closed position to the open position to allow withdrawal of the first arcuate anchor  135  and the second arcuate anchor  145  from the anterior side  126  of the body portion  120 . Withdrawal of first arcuate anchor  135  and second arcuate anchor  145  facilitates removal of the body portion from between the upper and lower vertebral bodies  105 ,  110 . 
     One feature that is optional, but not required, may be that the locking member comprises a lateral gate  155  (see  FIGS. 3A, 3B, 3C, and 3D ), and the movement path of the locking member is with the lateral gate pivoting on a hinge axis. 
     One feature that is optional, but not required, may be that the locking member comprises a cam or other non-circular rotating member  160  (see  FIGS. 4A and 4B ), and the movement path of the locking member is with the cam  160  pivoting on a cam axis  162  which is generally parallel to the Y-axis. The cam may have a radially extended segment that, upon pivoting on the cam axis, is movable generally transverse to the Y-axis to block the first arcuate anchor  135  and the second arcuate anchor  145  from withdrawal. 
     One feature that is optional, but not required, may be that the locking member comprises a lateral slide  165  (see  FIGS. 5A and 5B ), and the movement path of the locking member is along a track  168  that is generally transverse to the Y-axis. 
     One feature that is optional, but not required, may be that the first arcuate anchor  135  has a first front edge  137  that extends anteriorly of a front surface along the anterior side  126  of the body portion  120  when implanted and penetrating into the upper vertebral body  105 . Also the second arcuate anchor  145  has a second front edge  147  that extends anteriorly of the front surface along the anterior side  126  of the body portion  120  when implanted and penetrating into the lower vertebral body  110 . 
     One feature that is optional, but not required, may be that the first arcuate anchor  135  includes a first means for being grabbed by a tool for anterior withdrawal from the body portion. The second arcuate anchor  145  includes a second means for being grabbed by a tool for anterior withdrawal from the body portion. 
     One feature that is optional, but not required, may be that the first means for being grabbed may include a first hole  139  in the first arcuate anchor  135  located near the first front edge  137 . The second means for being grabbed may include a second hole  149  in the second arcuate anchor  145  located near the second front edge  147 . One feature that is optional, but not required, may be that the anchor  135 ,  145  includes an opening  139 ,  149  (see  FIG. 2 ). The openings may be configured to receive a removal tool hook  174  for removing the implant from between the upper vertebral body  105  and the lower vertebral body  110 . Removal tool hook  174  may be a dedicated tool; or, optionally it may be part of another tool such as a slap hammer  200  ( FIG. 6 ). Other tools, such as pliers may be used. Optionally, however, instead of or in addition to one or more such holes, the means may include other structure, including a ridge, groove, bump, high friction surface and/or combinations thereof. 
     One feature that is optional, but not required, may be that the body portion  120  is made of a metallic material having a Rockwell hardness [on the A-scale] of at least 35 making it resistant to destructive implant removal. 
     One feature that is optional, but not required, may be that the first arcuate anchor  135  does not have a detent lock for locking it permanently in place within the first pathway  130 . Also, optionally, the second arcuate anchor  145  does not have a detent lock for locking it permanently in place within the second pathway  140 . 
     One feature that is optional but not required is a cavity  101  ( FIG. 1 ) for bone chips and/or other bone fusion material. 
     With reference to  FIGS. 7-10 , an alternative embodiment of an intervertebral implant for implantation between an upper vertebral body  105  and a lower vertebral body  110  is shown. The intervertebral implant  300  includes a plate  325  that attaches to the body portion  320  of the intervertebral implant  300 . 
     Plate  325  (see  FIG. 9 ) has a top side  332  for contact with the upper vertebral body  105  and a bottom side  334  for contact with the lower vertebral body  110 . Plate  325  also includes and a posterior side  328  and an anterior side  326  between the top side  332  and bottom side  334 . Plate  325  defines in space a Z-axis generally in a cranial-caudal orientation therethrough and a Y-axis perpendicular to the Z-axis and passing through the anterior side  326  of plate  325 . 
     A first pathway  330  through plate  325  extends from the anterior side  326  to the top side  332  of plate  325 . A first arcuate anchor  335  is movable in an arcuate path through first pathway  330  to penetrate into the upper vertebral body  105 . 
     A second pathway  340  through plate  325  extends from the anterior side  326  to the bottom side  334  of plate  325 . A second arcuate anchor  345  is movable in an arcuate path through second pathway  340  to penetrate into the lower vertebral body  110 . 
     Plate  325  is adapted to be removably attachable to body portion  320 . Body portion  320  (see  FIG. 8 ) has a top side  322  for contact with the upper vertebral body  105  and a bottom side  324  for contact with the lower vertebral body  110 . Body portion  320  also includes and an anterior side  327  between top side  322  and bottom side  324 . 
     One or more locking member  155 ,  160 , or  165  (as shown in  FIGS. 3A, 4A, and 5A ) is selectively movable between an open position and a closed position in a movement path that is generally transverse to the Y-axis. Upon transverse movement of the locking member to the closed position, the locking member is located anteriorly of first arcuate anchor  335  and second arcuate anchor  345 , blocking their withdrawal from the anterior side  326  of plate  325 . 
     The locking member  155 ,  160 , or  165  is selectively movable along the generally transverse movement path from the closed position to the open position to allow withdrawal of first arcuate anchor  335  and second arcuate anchor  345  from the anterior side  326  of plate  325  to facilitate removal of the intervertebral implant  300  from between the upper and lower vertebral bodies. 
     One feature that is optional, but not required, may be that the anterior side  327  of body portion  320  may include a threaded connection interface, such as a tapped opening  329 , and the posterior side  328  of plate  325  also includes a threaded connection interface, such as a threaded member  336 . The threaded connection interfaces on body portion  320  and plate  325  may be mated to attach body portion  320  to plate  325 . As an example, threaded member  336  may be inserted into and engage tapped opening  329  to attach plate  325  to body portion  320 . In other embodiments, a tapped opening may be included on plate  325  and a threaded member may be included on body portion  320 . 
     One feature that is optional, but not required, may be that first arcuate anchor  335  has a first front edge  337  that extends anteriorly of a front surface along anterior side  326  of plate  325  when implanted and penetrating into the upper vertebral body  105 . Also, second arcuate anchor  345  has a second front edge  347  that extends anteriorly of the front surface along anterior side  326  of plate  325  when implanted and penetrating into the lower vertebral body  110 . 
     One feature that is optional, but not required, may be that first arcuate anchor  335  includes a first means for being grabbed by a tool for anterior withdrawal from plate  325 . Also, second arcuate anchor  345  includes a second means for being grabbed by a tool for anterior withdrawal from plate  325 . 
     One feature that is optional, but not required, may be that the first means for being grabbed comprises a first hole  339  in first arcuate anchor  335  located near first front edge  337 . The second means for being grabbed comprises a second hole  349  in second arcuate anchor  345  located near second front edge  349 . 
     One feature that is optional, but not required, may be that body portion  320  and plate  325  are made of a metallic material having a Rockwell hardness [on the A-scale] of at least 35 making it resistant to destructive implant removal. 
     One feature that is optional, but not required, may be that first arcuate anchor  335  does not have a detent lock for locking it permanently in place within first pathway  330 . Also, second arcuate anchor  345  does not have a detent lock for locking it permanently in place within second pathway  340 . 
     One feature that is optional, but not required, may be that the locking member comprises a lateral gate  155  (see  FIGS. 3A, 3B, 3C, 3D, and 10 ), and the movement path of the locking member is with the lateral gate pivoting on a hinge axis. 
     One feature that is optional, but not required, may be that the locking member comprises a cam  160  (see  FIGS. 4A, 4B, 4C ). The movement path is the cam pivoting on a cam axis which is generally parallel to the Y-axis. The cam has a radially extended segment that, upon pivoting on the cam axis, is movable generally transverse to the Y-axis to block first arcuate anchor  335  and second arcuate anchor  345  from withdrawal. 
     One feature that is optional, but not required, may be that the locking member comprises a lateral slide  165  (see  FIGS. 5A, 5B, 5C ). The movement path of lateral slide  165  is along a track that is generally transverse to the Y-axis. 
     One feature that is optional but not required is a cavity  301  ( FIG. 7 ) for bone chips an/dor other bone fusion material. 
     As used here (claims, specification, and other definitions) the following terms have the following meaning: 
     Articles and phases such as, “the”, “a”, “an”, “at least one”, and “a first”, “comprising”, “having” and “including” here are not limited to mean only one, but rather are inclusive and open ended to also include, optionally, two or more of such elements and/or other elements. In terms of the meaning of words or terms or phrases herein, literal differences therein are not superfluous and have different meaning, and are not to be synonymous with words or terms or phrases in the same or other claims. 
     The term “means for” in a claim invokes 35 U.S.C. §112(f), literally encompassing the recited function and corresponding structure and equivalents thereto. Its absence does not, unless there otherwise is insufficient structure recited for that claim element. Nothing herein or elsewhere restricts the doctrine of equivalents available to the patentee. 
     The term “and/or” is inclusive here, meaning “and” as well as “or”. For example, “P and/or Q” encompasses, P, Q, and P with Q; and, such “P and/or Q” may include other elements as well. 
     The term “anchor” as used herein has the meaning, an object used to attach and secure one object to another object. 
     The term “anterior” as used herein has the meaning, being situated nearest or toward the front of the body. With respect to the spine, the anterior is considered to be the side of the spine closest to the stomach or the throat. 
     The term “anteriorly” as used herein has the meaning, positioned in a location more anterior with respect to another object where the anterior refers to a position nearer to the front of a reference point. 
     The term “arcuate” as used herein has the meaning, to be curved, in an arc of a circle. 
     The term “arcuate path” as used herein has the meaning, a track or opening used to guide movement that has a generally arcuate, or curved, shape. 
     The term “blocking their withdrawal” as used herein has the meaning, positioned to obstruct and disallow the removal of an object. 
     The term “body portion” as used herein has the meaning, the main or principal part of an object. More specifically, it refers to a part of a vertebra implant that contacts the vertebral body of a neighboring vertebra. 
     The term “cam” as used herein has the meaning, a rotating part that is non-circular. 
     The term “contact” as used herein has the meaning, of two objects the state or condition of physical touching. As used, contact requires at least one location where objects are directly or indirectly touching, with or without any other member(s) material in between. 
     The term “cranial-caudal orientation” as used herein has the meaning, in the direction along an axis running vertically toward and away from a (standing) patient&#39;s skull. 
     The term “destructive implant removal” as used herein has the meaning, removal of an implant by causing harm or damage to the implant so it may not be reused after removal. 
     The term “detent lock” as used herein has the meaning, a locking mechanism that includes a snap-in lock. When engaged, the releasable part prevents motion, and motion is not allowed until the part is released. 
     The term “facilitate” as used herein has the meaning, to aid or help accomplish an action or a process to make that action or process easier. The act of facilitation does not need to accomplish the action or process entirely on its own. 
     The term “front edge” as used herein has the meaning, the outer limit of an object, where the term front is used to denote the anterior-most limit of the object. 
     The term “front surface” as used herein has the meaning, an exterior surface which may or may not be the anterior most surface. 
     The term “gate” as used herein has the meaning, a structure that swings on a pivot or hinge. 
     The term “hinge” as used herein has the meaning, a jointed device on which a swinging part is attached so that it may rotate about the joint. The hinge may allow the part to rotate in a full circle, or rotation may be limited to an arc. 
     The term “hole” as used herein has the meaning, a hollow opening within a body, structure, or an object. It can be any shape. 
     The term “locking it permanently” as used herein has the meaning, applying a lock to a structure so that it cannot be moved. Once the lock is put in place, it cannot be removed so that motion of the structure is never allowed absent destructive implant removal. 
     The term “locking member” as used herein has the meaning, an object used to prevent the movement of another object or objects. For example, a locking member may be any structure used to prevent the movement of an anchor. A locking member may be fixed or may be movable. 
     The term “means for being grabbed by a tool” as used herein has the meaning, any structure that is configured to be able to be gripped or seized or hooked by a tool. The structure may be a portion of, or connected to a larger structure. It may include holes, ridge, bumps, grooves, and high friction surfacing. 
     The term “pathway” as used herein has the meaning, a track or an open area that is used to guide the movement of another object. A pathway may take various shapes, for example, it may be straight and/or curved. 
     The term “perpendicular” as used herein has the meaning, meeting at a substantially 90 degree angle. Small variations from 90 degrees within the range of acceptable tolerance limits are allowed. 
     The term “plate” as used herein has the meaning, a portion of an intervertebral implant that is attachable to the body portion. A plate may be attached to the anterior side of the body portion or may be attached to a different side or multiple sides of the body portion. A plate may include pathways for receiving anchors or other objects. 
     The term “posterior” as used herein has the meaning, being situated nearest or toward the back of the body. With respect to the spine, the posterior is considered to be the side of the spine closest to the patient&#39;s back. The posterior is the opposite side from the anterior. 
     The term “removably attachable” as used herein has the meaning, to be able to fasten, connect, or join two separate objects in a manner that allows the objects to be detached without damaging the objects to the extent that the object could not be reused. 
     The term “removal tool” as used herein has the meaning, any structure or object that may be used to assist in the removal of the implant or anchor from between vertebral bodies without causing damage to the implant. As an example, the removal tool may be a wire, pliers, or a hook structure. 
     The term “Rockwell hardness” as used refers to the scale commonly used to determine the hardness of a material where hardness is determined based on the depth of penetration of an indenter. The A-scale uses a 120° diamond cone indenter with a 60 kgf load. 
     The term “side” as used herein has the meaning, one of the faces on the surface of an object. An object can have multiple faces with a variety of orientations. For example, an object may have a front side, a bottom side, a back side, or a top side. 
     The term “slide” as used herein has the meaning, a structure that is able to move along the surface, track or grove of another object. 
     The term “threaded connection interface” as used herein has the meaning, a surface that is adapted to attach to another surface using a threaded connection. One example of a threaded connection interface may be a surface that includes a tapped opening. Another threaded connection interface may be a surface that includes a threaded member extending from the surface that may be inserted into a threaded opening. Representative examples of threaded members include a screw, a nut and bolt, or a threaded rod. 
     The term “track” as used herein has the meaning, a path or a route that defines the movement of an object. When an object is on a track, the movement of that object is confined to the position of the track. 
     The term “transverse” as used herein has the meaning, situated or extending across an object or an axis. 
     The term “vertebral body” as used herein has the meaning, the largest, cylindrical part of a vertebra. The vertebra is a bone or object that forms part of the spinal column. The vertebral body could be composed of bone or it can be an implant formed from any variety of materials that would be useful to replace bone such as titanium, stainless steel, or other metallic or non-metallic compounds. 
     The term “withdrawal” as used herein has the meaning, the action of removing or taking away something for a particular location. 
     The term “Y-axis” as used herein has the meaning, a central line of a body orientated in the Y-direction. As used in this application with respect to the human body, the Y-direction is perpendicular to the Z-axis passing through the anterior side of the vertebral implant, for example, from the stomach to the back. 
     The term “Z-axis” as used herein has the meaning, a central line of a body orientated in the Z-direction. As used in this application with respect to the human body, the Z-direction follows a cranial-cradium orientation, extending from the head through the feet. 
     The invention may include any one or more articles or devices made by any of the claimed methods and/or may by different methods but with a claimed composition. 
     The language used in the claims and the written description and in the above definitions is to only have its plain and ordinary meaning, except for terms explicitly defined above. Such plain and ordinary meaning is defined here as inclusive of all consistent dictionary definitions from the most recently published (on the filing date of this document) general purpose Webster&#39;s dictionaries and Random House dictionaries. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes, equivalents, and modifications that come within the spirit of the inventions defined by following claims are desired to be protected. All publications, patents, and patent applications cited in this specification are herein incorporated by reference as if each individual publication, patent, or patent application were specifically and individually indicated to be incorporated by reference and set forth in its entirety herein.