Abstract:
An interbody fusion device is provided that includes an interbody cage, a fixation system and an actuation mechanism to deploy one or more blades. The cage acts as an intervertebral spacer and provides resistance to the compressive loads in the spinal column. The fixation system includes an anchor and a ramp. These components could be manufactured from various medical grade materials.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to U.S. Provisional Patent Application entitled “Interbody Fusion Device”, Ser. No. 61/145,787 filed on Jan. 20, 2009, which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to an interbody fusion device, such as that used in lumbar or cervical spine procedures for example, and in particular relates to a stand-alone interbody fusion device having a self-contained fixation system. 
     Interbody fusion devices are common in spine procedures today. These devices encompass many products in the marketplace. Implants are constructed from PEEK, titanium and various other materials and have been designed for insertion through anterior, posterior and lateral approaches. Typically, interbody devices require additional fixation to create a fusion across the intended vertebral level. In lumbar surgery, this supplemental fixation can include an anterior plate or pedicle screws and rods inserted posteriorly in a 360° procedure. Studies have shown that interbody devices have poor outcomes when they are not combined with a method of fixation. 
     One type of interbody fusion device is called a stand-alone. This type of implant consists of an interbody device and a means of fixation all in one. Typically this fixation has been accomplished using screws that are placed through the implant and fixed at oblique angles to the adjacent superior and inferior vertebrae. This method requires considerable access due to the extreme angle of insertion for the screws. 
     While existing interbody fusion devices are suitable for their intended purposes, improvements may be made. In particular, it is desirable to have a stand-alone interbody fusion device with an integrated fixation system that may be readily implanted while reducing the access needed by a surgeon during a spinal procedure. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In accordance with one embodiment of the invention, an interbody fusion device is provided having a cage. The cage includes a first contact surface and a second contact surface opposite the first contact surface. A ramp is coupled to the cage, the ramp includes a first surface thereon. A first anchor includes a body that is movably coupled within the cage, the first anchor has at least one blade extending from the body and an end adjacent the ramp. The at least one blade is arranged to cooperate with the first surface to direct the at least one blade from the first contact surface when the first anchor moves from the first position to the second position. 
     In accordance with another embodiment of the invention, an interbody fusion device for implanting between vertebrae is provided where the vertebrae have an anterior side and a posterior side. The interbody fusion device includes a cage having a first contact surface and a second contact surface. The cage also includes an anterior wall that is arranged between the first contact surface and the second contact surface. A ramp portion is arranged adjacent the anterior wall, and a first opening is arranged between the first contact surface and the second contact surface adjacent the ramp portion. An anchor is slidably coupled to the cage and includes at least one blade, wherein the anchor is movable between a first position towards the anterior wall to a second position, wherein the at least one blade cooperates with the ramp portion to move through the first opening when the anchor moves from the first position to the second position. 
     In accordance with another embodiment of the invention, an interbody fusion device is provided having a cage. The cage includes a pair of opposing contact surfaces and a wall on one end arranged between the contact surfaces. The cage further includes a center portion disposed adjacent the wall. The cage also includes a first opening extending through the contact surfaces between the center portion and the wall, a second opening arranged in the wall, and a third opening is arranged in the center portion. An anchor is slidably arranged in the third opening, the anchor has a body and at least one blade. The body is movable between a first position, within the cage, to a second position where the at least one blade extends through the first opening. 
     In accordance with one embodiment of the invention, a method of fusing adjacent vertebrae is provided where the vertebrae have an anterior side and a posterior side. The method includes the step of providing an interbody fusion device that includes a cage and an anchor with at least one blade. A surgical tool is coupled to the anchor. The interbody fusion device is inserted between the vertebrae. The surgical tool is actuated to translate the anchor from a first position to a second position with the at least one blade extending into at least one of the vertebrae. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed descriptions taken in conjunction with the accompanying drawings in which: 
         FIGS. 1-4  are an illustration of an interbody fusion device in accordance with an embodiment of the invention; 
         FIGS. 5-6  are an illustration of an interbody fusion device of  FIG. 1  with another embodiment cage and screw member; 
         FIGS. 7-10  are an illustration of an interbody fusion device of  FIG. 1  in the extended or deployed position; 
         FIGS. 11-13  are an illustration of an interbody fusion device of  FIG. 1  with an anchor curved during deployment; 
         FIGS. 14-17  are an illustration of an interbody fusion device in accordance with another embodiment of the invention; 
         FIGS. 18-19  are an illustration of an interbody fusion device of  FIG. 14  in the extended or deployed position; 
         FIGS. 20-22  are an illustration of an interbody fusion device in accordance with another embodiment of the invention; 
         FIGS. 23-25  are an illustration of another interbody fusion device in accordance with another embodiment of the invention; 
         FIG. 26-27  are an illustration of an interbody fusion device having multiple screw members and anchors in accordance with another embodiment of the invention; 
         FIG. 28  is a perspective view illustration of an interbody fusion device having multiple anchors in accordance with another embodiment of the invention; 
         FIG. 29  is a perspective view illustration of an interbody fusion device having multiple anchors arranged on an angle in accordance with another embodiment of the invention; 
         FIGS. 30-32  are an illustration of an exemplary anchor for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 33-37  are an illustration of another embodiment of an anchor for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 38-40  are an illustration of another embodiment of an anchor for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 41-43  are an illustration of another embodiment of an anchor having multiple blades for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 44-46  are an illustration of another embodiment of an anchor for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 47-49  are an illustration of another embodiment of an anchor having multiple blades for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 50-54  are an illustration of another embodiment of an anchor having multiple blades for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 55-56  are an illustration of another embodiment of an anchor having no teeth for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 57-61  are an illustration of another embodiment of an anchor used in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 62-63  are an illustration of another embodiment of an anchor for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 64-65  are an illustration of another embodiment of an anchor for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 66-67  are an illustration of another embodiment of an anchor for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 68-69  are an illustration of another embodiment of an anchor for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 70-71  are an illustration of another embodiment of an anchor for use in the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 72-76  are an illustration of another embodiment of an anchor having a smaller profile for use with the interbody fusion device shown in  FIGS. 1-29 ; 
         FIG. 77  is an illustration of the anchor of  FIGS. 72-76  assembled on an exemplary screw member; 
         FIG. 78-82  are an illustration of another embodiment of an anchor having multiple blades for use with the interbody fusion device shown in  FIGS. 1-29 ; 
         FIGS. 83-84  are an illustration of an embodiment of a ramp member used in the interbody fusion device of  FIGS. 1-19 ; 
         FIGS. 85-86  are an illustration of another embodiment of a ramp member used in the interbody fusion device of  FIGS. 1-19 ; 
         FIG. 87-88  are an illustration of another embodiment of a ramp member for use with the interbody fusion device shown in  FIGS. 1-19 ; 
         FIGS. 89-90  are an illustration of another embodiment of a ramp member used with in the interbody fusion device of  FIGS. 1-19 ; 
         FIGS. 91-92  are an illustration of another embodiment of a conical ramp member for use with the interbody fusion device shown in  FIGS. 1-19 ; 
         FIGS. 93-94  are an illustration of another embodiment of a conical ramp member for use with the interbody fusion device shown in  FIGS. 1-19 ; 
         FIGS. 95-96  are an illustration of another embodiment of a ramp member used with an anchor having multiple blades; 
         FIGS. 97-100  illustrate another embodiment of a ramp member for use with the interbody fusion device of  FIGS. 14-19 ,  28 - 29 ; 
         FIGS. 101-103  illustrate another embodiment of a ramp member for use with the interbody fusion device of  FIGS. 20-22 ; 
         FIGS. 104-107  are an illustration of an exemplary guide housing for use with the interbody fusion devices of  FIGS. 1-13 ; 
         FIGS. 108-111  are an illustration of a surgical tool for use with the interbody fusion device of  FIGS. 14-25 ; 
         FIG. 112  is a front plan view illustration of an exemplary interbody fusion device of  FIG. 14  inserted between vertebrae; 
         FIG. 113  is an side plan view illustration the superior vertebrae and the inferior vertebrae illustrated in phantom line of the exemplary interbody fusion device of  FIG. 106 ; and, 
         FIG. 114  is a front plan view illustration with the superior vertebrae and the inferior vertebrae illustrated in phantom line of the exemplary interbody fusion device of  FIG. 106 . 
     
    
    
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1-13 , an exemplary interbody fusion device  50  having an interbody cage  52  and a fixation device  54  is illustrated. The interbody cage  52  can be used alone with supplemental fixation, such as rods and screws or a plate for example, or with the included fixation device  54 , thereby providing a stand-alone design. The interbody cage  52 , can be constructed of various biocompatible materials including, but not limited to, titanium or a polymer such as polyetheretherketone (PEEK) for example. With the fixation device  54  in place, the interbody fusion device  50  would be placed between the adjacent vertebrae after the partial or complete disc removal as illustrated in  FIGS. 112-114 . Once in place, the fixation device  54  would be actuated through a screw member  56 . This action would deploy the anchor  58  or anchors into the adjacent superior and inferior vertebral bodies  112 ,  114  ( FIG. 112 ), thereby fixing the implant in place. Thus the interbody fusion device  50  provides advantages in that supplemental fixation, such as pedicle screws and rods or an anterior plate for example, and its associated increased surgical time, is obviated. Further, the interbody cage  52  may include an optional opening  60  that may be used for autograft or alternative biomaterials to facilitate bone in-growth. The surgeon may utilize a tool or tools to facilitate the insertion of the interbody fusion device  50 , in conjunction with features  75  for example, to both place the interbody fusion device  50  and provide a means for actuation of the screw member  56  to deploy the fixation device  54 . 
     It should be appreciated that while the interbody cage  52  is illustrated with the opening  60 , this is for exemplary purposes and the claimed invention should not be so limited. For example, in different applications, it may be desirable to have the interbody cage  52  be substantially solid for example. While the exemplary embodiment discusses the spinal procedures with respect to an anterior insertion approach, the claimed invention may also be used in other spinal procedures, such as but not limited to posterior insertion and lateral insertion for example. 
     As used herein the term “anterior” refers to the front side from the perspective of the patient, while the term “posterior” refers the backside from the perspective of the patient. Further, as used herein, the term “superior” means closer to the head of the patient and “inferior” means closer to the feet of the patient. 
     The interbody cage  52  is a generally oblong shaped member sized to tightly fit between vertebrae. The interbody cage  52  tapers from the anterior side  62  to the posterior side  64  to match patient anatomy. In the exemplary embodiment, the top contact surface  66  and bottom contact surface  68  include a plurality of optional teeth or grooves  70  that engage the adjacent superior and inferior vertebrae to assist in maintaining the interbody fusion device  50  in place. 
     It should be appreciated that the taper, or angle between the contact surfaces  66 ,  68  may be varied to match the patient anatomy. The height, or distance between the contact surfaces  66 ,  68  may also be changed to match the patient anatomy. Further, while the contact surfaces  66 ,  68  are illustrated as being substantially flat and tapered, other profiles may be used, including but not limited to parallel surfaces or convex surfaces for example. Additionally, the interbody cage  52  may be cylindrical, such as that shown in U.S. Pat. No. 5,782,919, which is incorporated by reference in its entirety. 
     In the embodiments illustrated in  FIG. 1-13 , the interbody cage  52  includes an opening sized to receive the screw member  56 . The screw member  56  includes an actuation portion  72  that is configured to interact with a tool to allow the surgeon to rotate the screw member  56  after implanting the interbody fusion device  50  between the desired vertebrae. In one embodiment, the actuation portion  72  may be a hexagonal head that extends from the interbody cage  52 , such as that shown in  FIGS. 1-4  for example. Alternatively, the actuation portion  72  may rest within an opening  74  such that the actuation portion  72  is contained within the interbody cage  52 , such as is shown in  FIGS. 5-6  for example. In one embodiment, the opening in interbody cage  52  for the screw member  56  extends through the interbody cage  52  as shown in  FIG. 6 . In this embodiment, the screw member  56  is captured in the interbody cage  52  by a retaining member or feature, such as a snap ring  76  for example. Alternatively, the retaining member may be adjacent the actuation portion  72 . 
     It should be appreciated that in those embodiments where the insertion access point is not anterior, the location of the actuation portion  72  may be changed. In general, the position of the actuation portion  72  will be such that the actuation portion  72  will be oriented toward the surgeon&#39;s access point. 
     The interbody cage  52  also includes a pair of slots  71 ,  73  adjacent and centrally located within the opening  60 . The anterior slot  71  captures a ramp member  94  while the posterior slot  73  captures a guide housing  92 . The guide housing  92  also includes a body portion  96  ( FIG. 104-107 ), which when inserted into the interbody cage  52  as illustrated in the exemplary embodiment, substantially bifurcates the opening  60  to define the graft/biomaterial packing space. Pairs of projections  98  extend from the guide housing  92  and engage the ramp member  94 . The guide housing  92  also includes a center bore  95  that is sized to receive the screw member  56 . As will be discussed in more detail below, the center bore  95  may include one or more features  90  that are arranged to cooperate with features on the anchor  58 , which is slidably arranged in the center bore  95 . The body portion  96  also provides additional advantages with embodiments using a screw member  56  by covering the thread portion of the screw member  56  and inhibiting the migration of graft/biomaterial into the threads. It should be appreciated that in embodiments having a substantially solid interbody cage  52 , the body portion  96  may be altered since the threads will not need to be shielded from the graft/biomaterial. 
     Referring now to  FIGS. 14-19 , another embodiment of the interbody fusion device  50  is shown. This embodiment is similar to the embodiment of  FIGS. 1-13  including a interbody cage  52  having contact surfaces  66 ,  68 . An anterior wall  65  includes slot  71  to capture a ramp member  94 , such as the ramp member  94  embodiment shown in  FIG. 97  for example. As will be discussed in more detail below, in one embodiment the ramp member  94  and the slot  71  include features that cooperate to allow the ramp member  94  to be attached to the interbody cage  52  by a snap-fit coupling. 
     The anterior wall further includes a pair of features  75 , such as a threaded hole for example, to facilitate the attachment of an insertion tool as discussed in more detail below. The interbody cage  52  further includes a center portion  67  that provides the functionality of the guide housing  92  discussed above. In one embodiment, the center portion  67  bifurcates the interbody cage  52  to define the openings  60  to allow the insertion of graft/biomaterial. The center portion  67  extends from the posterior wall  63  towards the ramp member  94 . Pair of arms  77  project from the center portion  67  to connect the center portion  67  to the anterior wall  65 . A wall  81  is arranged on the end of the center portion  67 , separating the arms  77 . As with the guide housing  92 , an opening or center bore  95  is formed in the center portion  67  through wall  81 . Slidably arranged within the center bore  95  is the anchor  58 . The center bore  95  may include features  90  to orient the anchor  58  in the center bore  95 . The center bore  95  is arranged in the center portion  67  to be substantially co-axial with an opening  93  in the ramp member  94 . 
     The embodiment of  FIGS. 14-19  does not include a screw member  56 . Instead, the interbody fusion device  50  cooperates with a surgical tool  170 , such as the one illustrated in  FIGS. 108-111  for example. The surgical tool includes a shaft  171  having a capturing portion, such as a threaded end  172  for example, that is sized to be received in the opening  93  of ramp member  94 . In this embodiment, the threaded end  172  is further adapted to couple to the threaded portion  78  of the anchor  58  (see for example  FIGS. 30-32 ). As will be discussed in more detail below, after the threaded end  172  is coupled to the anchor  58 , the surgical tool  170  is actuated, such as by rotating a actuation knob  186  for example, causing the shaft  171  to move axially within the surgical tool  170 . Since the surgical tool  170  is firmly coupled to the interbody cage  52 , this results in the axial movement of the anchor  58  towards the ramp member  94 . As the surgical tool  170  continues to be actuated, the blade  80  will contact the ramp member and deflect through the openings  91  in the contact surfaces  66 ,  68 . While the threaded end  172  is illustrated, this is for exemplary purposes, and other capturing portions or geometries may be used. 
     Another embodiment of interbody fusion device  50  is illustrated in  FIGS. 20-22 . This embodiment is similar to the embodiment of  FIG. 14-19  wherein the interbody cage  52  includes contact surfaces  66 , 68  and a center portion  67  that bifurcates the interbody cage  52  to define openings  60 . In this embodiment, the anterior wall  65  includes a slot  97  that divides the anterior wall  65  into two sections. The slot  97  is sized to receive a ramp member  94 , such as the ramp member  94  illustrated in  FIG. 94  for example. In this embodiment, the ramp member  94  is inserted axially into the slot  97  rather than transversely through one of the contact surfaces  66 ,  68 . The ramp member  94  includes an opening  93  that is arranged co-axially with the center bore  95  of the center portion  67 . The anchor  58  is slideably arranged in the center bore  95 . The opening  93  is sized to receive the shaft  171  to allow the anchor  58  to be deployed from the retracted position to the extended position with the blade  80  extending through the opening  91  as discussed above. 
     Another embodiment of the interbody fusion device  50  is illustrated in  FIGS. 23-25 . This embodiment is similar to the embodiment of  FIG. 14-19  where the interbody cage  52  includes contact surfaces  66 ,  68  and a center portion  67  that bifurcates the interbody cage  52  to define openings  60 . In this embodiment, the ramp member  94  is integrated into the interbody cage  52 , wherein the anterior wall  65  includes a projection  99  that extends into the opening  91 . The projection  99  includes a ramp surface  102  that deflects the blade  80  through the opening  91  as the anchor  58  is moved from the first or retracted position to a second or extended position. The anterior wall  65  includes an opening  104  that is arranged co-axial with the center bore  95 . 
     Since the interbody fusion device  50  illustrated in  FIGS. 23-25  does not have a separate ramp member  94 , the opening  104  needs to be sized to be larger to allow the anchor  58  to be installed. In order for the anchor  58  to engage the ramp surface  102 , the anchor  58  may have a flared piercing portion  84 , such as the anchor illustrated in  FIG. 33-37 ,  44 - 54 , or  62 - 63 , whereby the flared end is compressed as the anchor  58  is inserted. Once the anchor  58  is installed and the flared end released, the flared end would be arranged in the opening  91 . In another embodiment, the anchor  58  is installed through the opening  104  and a tool is used to deform the anchor piercing portion  84  to bend up into the opening  91 . In other embodiments, the center portion  67  may include an additional opening or slot (not shown) that allows the insertion of the anchor  58  from either the top contact surface  66 , the bottom contact surface  68  or through the side wall. 
     In some embodiments, the interbody fusion device  50  may include multiple anchors  58  as shown in  FIGS. 26-27 . In this embodiment, there may be two or more screw members  56  each having an actuation portion  72 , coupled to the interbody cage  52 . Each screw member  56  has an anchor  58  (or anchor  154 ) coupled within a guide housing  92 . In other embodiments (not shown), there may only be a single actuation portion  72  that drives both anchors  58  during deployment. It should be appreciated that the embodiment of  FIGS. 26-27  may also be configured without the screw member  56  with the anchor being deployed in a similar manner to that described in the embodiments of  FIGS. 14-25 . 
     Another embodiment of an interbody fusion device  50  having multiple anchors is illustrated in  FIGS. 28-29 . In the embodiment of  FIG. 28 , the anchors  58  are arranged substantially perpendicular to the anterior wall  65 . In the embodiment of  FIG. 29 , the anchors  58  are arranged on an angle relative to the anterior wall  65 . These embodiments include an interbody cage  52  having contact surfaces  66 ,  68 . The anterior wall  65  includes a pair of slots  71 , each of which captures a ramp member  94 , such as the ramp member  94  shown in  FIG. 97  for example. The ramp member  94  and the slot  71  cooperate to allow the ramp member  94  to be attached to the interbody cage  52  by a snap fit coupling. Each ramp member  94  includes an opening  93  that is arranged substantially co-axial with the opening  95  in the interbody cage  52 . 
     The anterior wall  65  includes a feature  75 , such as a threaded hole for example, to facilitate the attachment of an insertion tool as discussed in more detail below. In one embodiment, the feature  75  is centered on the anterior wall  65  between the slots  71 . An opening  60  is arranged centrally in the interbody cage  52  that extends through the contact surfaces  66 ,  68  to allow the insertion of graft/biomaterial. Arms  71  are arranged between the opening  60  to define a second opening  91  adjacent the each ramp member  94  in a similar manner to that described above with respect to the embodiment of  FIGS. 14-19 . In the embodiment of  FIG. 29 , two additional openings  60  to allow insertion of graft/biomaterial are provided adjacent center portion  67 . 
     As discussed above in reference to the embodiment of  FIGS. 14-19 , a surgical tool, such as surgical tool  170  for example, is coupled to the interbody fusion device  50  via feature  75  and the anchors  58  via the openings  93 . The surgical tool is arranged to move the anchors  58  within the opening  95  between the first retracted position to a second extended position. The surgical tool may have a single shaft and capturing portion as illustrated in  FIGS. 108-111 , or may have multiple shafts (not shown) that may individually or simultaneously deploy the anchors. 
     It should also be appreciated that in embodiments where the height of the interbody cage  52  is increased, the outside profile of the guide housing  92 , such as the height of the body portion  96  for example, will also increase in proportion to the interbody cage  52 . In some embodiments, the anchor  58  may increase in height, or have longer blade  80 . The interbody fusion device  50  may include additional features, such as a locking mechanism or member that prevents movement of the anchor  58  after it is deployed by the surgeon. The locking member may take several forms, including but not limited to a setscrew or a cap (not shown) that engages the actuation portion  72  of screw member  56 , such as in opening  74  for example. 
     It should also be appreciated that while the embodiments herein illustrate the guide housing  92  and the center portion  67  as extending substantially normal to the anterior side  62  and posterior side  64 , this is for exemplary purposes and the claimed invention should not be so limited. In other embodiment, such as those used in procedures using a lateral insertion of the interbody fusion device  50  for example, the guide-housing  92 /center portion  67  may be oriented on an angle relative to the anterior side  62  and posterior side  64 . In one embodiment, the guide-housing  92 /center portion  67  is arranged substantially parallel to the anterior wall  65  and the posterior wall  63 . 
     It should further be appreciated that while the embodiments disclosed herein refer to the screw member  56  actuation portion  72  or the surgical tool  170  as being arranged on the anterior side  62 , this is for exemplary purposes and the claimed invention should not be so limited. In some embodiments, such as those used in procedures using posterior insertion of the interbody fusion device  50  for example, the screw member  56  actuation portion  72  or the surgical tool  170  may be accessed from the posterior side  64  or another lateral position. It should also be appreciated that in some embodiments, the anchor  58  may be actuated from a lateral or posterior position. 
     As discussed above, the anchor  58  is slidably retained in the center bore  95 . The anchor is movable in the center bore  95  whereby the anchor  58  is slid toward the ramp member  94  from a retracted or first position, shown in  FIGS. 2 ,  6  and  17  for example, to an extended or second position, shown in  FIGS. 8 ,  12  and  19  for example, where the blade member extends through the opening  91 . In some embodiments, such as those illustrated in  FIGS. 1-13  for example, the screw member  56  moves the anchor  58 . In other embodiments, such as those illustrated in  FIGS. 14-25  for example, the surgical tool  170  moves the anchor  58 . It should be appreciated that the anchor  58  may include a number of different features, as shown in  FIGS. 30-82  for example. Some of these features include, but are not limited to an anchor having: two blades; four blades ( FIGS. 41-43 ,  47 - 54 ); blades with slots ( FIGS. 30-32 ,  38 - 43 ,  57 - 61 ,  62 - 65  and  68 - 69 ); blades with teeth ( FIGS. 33-37 ,  44 - 49 ,  50 - 54  and  68 - 69 ); blades with teeth and slots; flat bladed anchors ( FIGS. 33-37 ,  44 - 49  and  50 - 54 ); and curved anchors ( FIGS. 30-31 ,  38 - 43 ,  55 - 56 ,  57 - 61 , and  62 - 69 ) or a combination of the foregoing for example. 
     The anchor  58  includes a body  82  with threaded portion  78  that engages the screw member  56  or the shaft  171 . One or more blades  80  extend from the body  82  and extend substantially parallel to the center bore  95 . Opposite the body  82 , each blade  80  includes a piercing portion  84 . The piercing portion  84  may be flat as shown in  FIG. 30 , or flared/curved as shown in  FIG. 35  for example. The piercing portion  84  may further include a tapered region  101 . In embodiments having multiple blades  80 , a slot  105  may be arranged between adjoining blades, such as is shown in  FIGS. 41-43  and  FIGS. 47-49  for example. The slot  105  may extend substantially the entire length of the blade  80 , or alternatively may be shorter in length, such as extending to the midpoint of the blade  80  for example. The teeth  86  may extend in a plane parallel to the blade  80 , as shown in  FIG. 36 , or the blade  80  may be curved and the teeth  86  conforming to the shape of the blade  80 . 
     In the exemplary embodiments, such as that shown in  FIGS. 30-32  and  57 - 61  for example, the blade  80  includes slots  85  that extend from an edge  79  of the blade  80 . The slots  85  include a curved portion  83 , surface  87 , and a relief area  89 . The curved portion  83  removes material from the blade  80  that may facilitate the bending of the blade  80  during deployment. Similarly, the relief area  89  facilitates bending and also reduces the stress in the blade  80 , lowering the potential for stress fractures. This embodiment may provide further advantages in that the surface  87  may provide further resistance to withdrawal of the blade  80  from the vertebrae. 
     In the exemplary embodiment, the anchor  58  may also include one or more features  88  on the body  82 . The features  88  may be an inward cylindrical shape as illustrated in  FIG. 30 , or may have other profiles such as but not limited to an outward cylindrical shape and a flat surface for example. The feature  88  may be shaped to match an adjacent feature  90  on the guide housing  92  or the center portion  67 . The features  88 ,  90  cooperate to maintain the anchor  58  properly oriented during assembly and while the blades  80  are being deployed during a spinal procedure. It should be appreciated that the features  88 ,  90  may take other forms that allow the anchor  58  properly oriented, such as a pin and a slot for example. 
     In the exemplary embodiment, the anchor  58  is made from a material, such as titanium for example, that may be defined by a stress-strain curve having an elastic range and a plastic range. As used herein, this means that if the stress on the material does not exceed the materials elastic limit, the article may be repeatedly deformed and the article will return to its original shape. Once the elastic limit is exceeded, the material plastically deforms and the article does not return to its original shape. In the exemplary embodiment, the blade  80  is arranged to plastically deform as anchor  58  is moved from the retracted or first position to the extended or second position. By plastically deforming the blade  80 , advantages are gained in obviating the need for a locking arrangement to keep the anchor  58  in place. 
     Some of the embodiments the anchor  58  may also include additional features and advantages. For example, the anchors  58  shown in  FIGS. 66-67  and  70 - 71  include recesses  118  along the outside surface of the blade  80 . These recesses  118  facilitate the bending of the blade  80  during deployment, reducing the amount of force the surgeon needs to apply. It should also be appreciated that some of the anchor embodiments also include different teeth  86  profiles that provide differing levels of engagement with the vertebrae  112 ,  114 . 
     Referring now to  FIGS. 72-77 , an embodiment of a lower profile lower profile anchor  120  is illustrated. The lower profile lower profile anchor  120  includes a body  122 . The blade portion  124  includes a substantially open center section  126  that extends from the piercing portion  128  back to or through the threaded portion  130 . This allows the lower profile anchor  120  to be installed on the screw member  56  with the portion  132  of the body  122  to extend along the surfaces  102 ,  104 ,  150  (for surface  15 , see for example  FIGS. 91-94 ). Thus, the height of the body  122  may be sized to be substantially equal to or less than the diameter of the screw member  56 . This may allow a reduction in the height of the interbody fusion device  50  providing advantages in certain spinal procedures, such as cervical fusion for example. 
     Referring now to  FIGS. 78-82 , another anchor  154  is illustrated having three blades  156 ,  158 ,  160 . Two of the blades  156 ,  158  are arranged to deploy into the one of the vertebra while the third blade  160  is arranged to deploy into the opposing vertebra. In circumstances where either a longer blade  80  is used or patient anatomy includes narrower vertebrae, this embodiment may provide additional advantages when multiple interbody fusion devices are being implanted in a patient. The arrangement of the blades  156 ,  158 ,  160  in this manner allows multiple interbody fusion devices to be implanted, in adjacent levels of vertebrae, without blades from the adjacent devices interfering with each other. 
     Referring now to  FIGS. 83-103 , embodiments of the ramp member  94  will be described. It should be appreciated that the ramp member  94  may be coupled to the interbody cage  52  in several ways. The ramp member  94  may be coupled by a snap-fit connection, as illustrated in  FIG. 14  for example, or may also be captured on the screw member  56  within the anterior slot  71 , as shown in  FIG. 2  for example. Other coupling means include, but are not limited to, press fit, bonding or mechanical fasteners. In other embodiments, the ramp member  94  may be incorporated into the surgical tool and therefore removed from the patient at the conclusion of the surgical procedure. The ramp member  94  includes one or more surfaces  102  that cooperate with the blade  80  to urge the piercing portion  84  away from the screw member  56  extending the blade from the contact surfaces  66 ,  68  and into the vertebrae. In some embodiments, the ramp member  94  may include four surfaces  102 ,  104  ( FIGS. 85-86 ,  89 - 90 ) or a frustoconical surface  150  ( FIGS. 91-93 ), that urge the separation and spreading of the blades  80  on a multi-bladed bladed anchor ( FIGS. 41 ,  47 ,  50 ). One embodiment also includes a projection  106  ( FIGS. 95-96 ) that further separates and provides additional deflection of the multiple blades of the anchor. The ramp member  94  may also include a pair of slots  108 ,  110  that are sized to receive the projections  98  on the guide housing  92 . It should be appreciated that the embodiments illustrated in  FIGS. 83-103  may also include the slots  108 ,  110 . The surfaces  102 ,  104  may be a sloped planar surface, an arcuate surface, or have first curvature and a second curvature to form a saddle shaped surface as illustrated in  FIGS. 97-100  for example. 
     For exemplary purposes, the embodiment of the ramp member  94  illustrated in  FIGS. 97-100  will be described. In this embodiment, the ramp member  94  includes a body  134  that is sized to fit in the anterior slot  71 . A first projection  136  extends from the body  134 , in the embodiment of  FIG. 14  the first projection  136  extends towards the anterior side  62 . The first projection includes a profiled portion  138  that cooperates with a substantially similarly shaped portion of the anterior slot  71  to define a snap-fit connection. The snap-fit defined by the profiled portion  138  retains the ramp member  94  in the anterior slot  71  preventing migration of ramp member  94  during use. Opposite the first projection  136 , a second projection  140  extends from the body  134 . The second projection includes a pair of surfaces  102  that are arranged to deflect the blade  80  through the opening  91 . In the embodiment illustrated in  FIGS. 97-100 , the surface  102  has first curvature sized and shaped to substantially match the curvature or radius of the blade  80 . The surface  102  is also defined by a second curvature sized and shaped to deflect the blade  80  through the opening  91  with the desired exit angle and curvature. The first curvature and the second curvature combine to form a substantially saddle shape. In some embodiments, the first curvature lies substantially in a plane parallel to the longitudinal axis of the body, while the second curvature lies in a transverse plane to the first curvature forming a saddle shape. The ramp member  94  also includes an opening  93  that extends through the first projection  136 , the body  134  and the second projection  140 . In some embodiments, the opening  93  is large enough to separate the surfaces  102  forming a gap  142  in the second projection  140 . 
     Another exemplary embodiment of the ramp member  94  is illustrated in  FIGS. 101-103 . This embodiment of ramp member  94  may be used with an interbody cage  52 , such as that illustrated in  FIG. 20  for example, where the ramp member  94  is inserted axially into the interbody cage  52 . In this embodiment, the ramp member  94  includes a body  144  having a central opening  93 . A pair of first projections  146  extends from the body  144  and each is sized to be received in the anterior slot  71 . On one end of the body  144 , a pair of surfaces  102  is formed. In one embodiment, the surfaces  102  extend from the body  144  onto one end of the first projections  146 . Extending from the body  144 , adjacent the surfaces  102 , a pair of second projections  148  extend substantially parallel to the opening  93 . The second projections  148  assist the separation of the blades  80  as the anchor  58  is moved. 
     Referring to  FIGS. 108-111 , an embodiment of a surgical tool  170  for use with the interbody fusion device  50  is illustrated. The surgical tool  170  includes a handle  176 . Extending from one end of the handle  176  is an elongated first shaft  178  with a support member  180  on a distal end. The support member  180  is generally sized and shaped to couple to the interbody fusion device  50 . A second shaft  182  is coupled to the first shaft  178 . The second shaft  182  includes an actuation portion  184  on an end adjacent the handle  176 . Opposite the actuation portion  184 , the second shaft  182  includes a threaded portion  192  that extends through the support member  180  and is adapted to couple with the feature  75  in the interbody fusion device  50 . It should be appreciated that in embodiments using the screw member  56 , the end of the shaft  171  is configured to engage the actuation portion  72  of the screw member  56 . 
     The surgical tool  170  also includes a shaft  171  having a threaded rod  172  that extends from the handle  176  through the support member  180 . A knob  174  is coupled to the threaded rod  172  allowing the surgeon to rotate the shaft  171  and couple the end of the threaded rod  172  into the anchor  58 . It should be appreciated that once the second shaft  182  is coupled to the feature  75  and the shaft  171  is inserted through the opening in either the interbody cage  52  or the ramp member  94  and coupled to the anchor  58 , the interbody fusion device  50  and the surgical tool  170  are securely coupled together. 
     The surgical tool  170  also includes a second or actuation knob  186  arranged on one end. The actuation knob  186  is coupled to the shaft  171  via a threaded portion  188 , as is known in the art, to cause the shaft  171  to move axially within the handle  176  and first shaft  178 . As the actuation knob  186  is actuated, the shaft  171  moves the anchor  58  relative to the interbody cage  52 . It should be appreciated that the actuation of the actuation knob  186  can be used to cause the anchor to move from the retracted or first position to the extended or second position or vice versa. As will be discussed in more detail below, once the procedure has been completed, the surgeon uses the knob  174  to disengage the shaft  171  from the anchor  58  and the actuation portion  184  to disengage the second shaft  182  from the interbody cage  52 . 
     It should be appreciated that in embodiments where the interbody fusion device has a screw member  56 , the shaft  171  includes an end adapted to couple with the screw member actuation portion  72 . Further, in some embodiments, a third shaft  190  may be coupled to the first shaft  178  opposite the second shaft  182 . The third shaft  190  would be arranged to extend through the support member  180  and couple to the feature in the interbody cage  52 . The third shaft  190  may be a pin as illustrated in  FIG. 111 , or have a threaded end similar to the second shaft  182 . 
     It should be appreciated that while this embodiment illustrates a single surgical tool  170 , in other embodiments, multiple surgical tools may be used for insertion, deployment, retraction, and/or removal. 
     During the surgical procedure, the surgeon couples the surgical tool to the interbody fusion device  50  by coupling the second shaft  182  to the feature  75  in interbody fusion cage  52  and inserting the shaft  171  into the interbody fusion device  50 . The surgeon rotates knob  174  to rotate shaft  171  and couple the threaded rod  172  to the threaded portion  78  of anchor  58 . If desired, the surgeon may also use the optional third shaft  190  to further couple the surgical tool  170  to the interbody fusion device  50 . 
     The surgeon gains access to the intended surgical site and removes the disc material from between the desired superior vertebrae and inferior vertebrae. With the disc material removed, the surgeon uses the surgical tool  170  to guide the interbody fusion device  50  to the intended implantation site. The interbody fusion device  50  is inserted between a superior vertebra  112  and inferior vertebra  114  as shown in  FIGS. 112-114 . When the surgeon actuates the actuation knob  186 , the shaft  171  is moved axially within the surgical tool pulling the anchor  58  from the retracted or first position (e.g.  FIGS. 2 ,  17 ) towards the extended or second position (e.g.  FIGS. 8 ,  19 ). It should be appreciated that in embodiments having a screw member  56 , the anchor  58  is deployed from its initial position within the guide housing  92  through the rotation of the screw member  56 . 
     As the actuation knob  186  continues to be rotated, the anchor  58  is moved with the blade  80  contacting the ramp member  94 . It should be appreciated that the center portion  67  or guide housing  92  keeps the anchor  58  centered within the interbody cage  52  and the features  88 / 90  provide a means for preventing rotation of the anchor  58 . Further, the leading edge  100  of the guide housing  92  cooperates with the ramp member  94  to define a gap. This gap defines both the angle the blade  80  exits the contact surfaces  66 ,  68 , and the deformation or curvature of the blade  80  as the anchor is moved to the final position. 
     As the actuation knob  186  is rotated, the anchor  58  advances axially and the blade  80  deforms projecting outward by the surface  102  (and in some embodiments surface  104  or surface  150  as well). In the exemplary embodiment, the anchor  58  is advanced toward the anterior side  62 . The anchor(s), in whichever embodiment, pierce the cortical shell  116  of the adjacent superior and inferior endplates and extend into the vertebral bodies  112 ,  114  as shown in  FIG. 113 . In some embodiments, the blades  80  remain substantially straight while engaging the vertebral bodies  112 ,  114  ( FIG. 8 ,  FIG. 115 ). In other embodiments, the blade  80  may be arranged to curve while deploying into the vertebral bodies  112 ,  114  ( FIGS. 12 ,  19 ). In the embodiments, the curving of blade  80  in a direction opposite the direction of motion of the blade body  82  (e.g. towards the posterior side) may provide additional advantages in securing the interbody fusion device  50  to the vertebral bodies  112 ,  114  and prevent the anchor  58  from moving. This curving of the blade  80  may also provide further advantages in resisting extension of the vertebrae and in lateral bending. As discussed above, in one embodiment, the blade  80  plastically deforms, meaning the blade  80  material is stressed beyond the elastic limit. The plastic deformation of the blade  80  provides advantages in reducing or eliminating a locking member. 
     Once the anchor  58  is moved to the extended or final position, the surgeon rotates the knob  174  in the opposite direction causing the threaded rod  172  to disengage from the threaded portion  78  of the anchor. Once the shaft  171  is decoupled from the anchor  58 , the surgeon rotates the actuation portion  184  to disengage the second shaft  182  from the interbody cage  52 . With the surgical tool  170  decoupled from the interbody fusion device  50 , the surgeon can remove the surgical tool from the patient. 
     In some circumstances it may be desirable for the surgeon to remove, or reposition the interbody fusion device  50 . For example, there may be complications in an unrelated part of the surgery, or the surgeon may want to reposition the interbody fusion device  50  to provide better support. One advantage of the interbody fusion device  50  is that the surgeon may utilize the surgical tool  170  in reverse to retract the anchor  58  and the blades  80  into the interbody cage  52 . To accomplish this, the surgeon attaches the surgical tool to the interbody fusion device  50  via the second shaft  182  and the shaft  171  to the opening  74  and the anchor threaded portion  78  respectively. The actuation knob  186  is then rotated causing the shaft  171  to slide axially away from the actuation knob  186  and pushing on the anchor  58 . As the shaft  171  pushes on the anchor  58 , the anchor slides causing the blades  80  to retract into the center bore  95 . Once the blades  80  are retracted, the surgeon may remove or reposition the interbody fusion device  50  as desired. It should be appreciated that in embodiment utilizing the screw member  56 , the blades  80  are retracted in a similar manner by rotating the screw member  56  in the opposite direction. 
     The interbody fusion device  50  provides advantages that include the rigid fixation of the stand-alone implant. The interbody fusion device  50  provides additional advantages in resisting motion typically seen in the spinal column such as lateral bending, torsion and extension. The rigidity afforded by this interbody fusion device  50  fixes the adjacent superior and inferior vertebral bodies together allowing for a fusion to occur across the spinal segment. The interbody fusion device  50  provides additional advantages in that the anchor may be moved in both directions to allow deployment, removal, or repositioning. The interbody fusion device  50  also provides advantages in that a single surgical tool may be used to insert, deploy, and remove the implant. The interbody fusion device  50  provides further advantages in that it may be used from an anterior, a lateral or a posterior direction. In some embodiments, the interbody fusion device  50  provides yet further advantages in that the blades are deployed towards the anterior side of the patient and away from the spinal cord. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.