Abstract:
The present invention relates to devices and methods for treating one or more damaged, diseased, or traumatized portions of the spine, including intervertebral discs, to reduce or eliminate associated back pain. In one or more embodiments, the present invention relates to an expandable interbody spacer. The expandable interbody spacer may comprise a first jointed arm comprising a plurality of links pivotally coupled end to end. The expandable interbody spacer further may comprise a second jointed arm comprising a plurality of links pivotally coupled end to end. The first jointed arm and the second jointed arm may be interconnected at a proximal end of the expandable interbody spacer. The first jointed arm and the second jointed arm may be interconnected at a distal end of the expandable interbody spacer. The first jointed arm and the second jointed arm may each be configured to fold inward in opposite directions to place the expandable interbody spacer in an expanded position.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation application of U.S. patent application Ser. No. 13/483,852, filed May 30, 2012, which is entitled “Expandable Interbody Spacer.” The entire contents of the application are hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to devices and methods for treating one or more damaged, diseased, or traumatized portions of the spine, including intervertebral discs, to reduce or eliminate associated back pain. In one or more embodiments, the present invention relates to an expandable interbody spacer. 
       BACKGROUND OF THE INVENTION 
       [0003]    The vertebrate spine is the axis of the skeleton providing structural support for the other body parts. In humans, the normal spine has seven cervical, twelve thoracic and five lumbar segments. The lumbar spine sits upon the sacrum, which then attaches to the pelvis, and in turn is supported by the hip and leg bones. The bony vertebral bodies of the spine are separated by intervertebral discs, which act as joints but allow known degrees of flexion, extension, lateral bending, and axial rotation. 
         [0004]    The typical vertebra has a thick anterior bone mass called the vertebral body, with a neural (vertebral) arch that arises from the posterior surface of the vertebral body. The central of adjacent vertebrae are supported by intervertebral discs. Each neural arch combines with the posterior surface of the vertebral body and encloses a vertebral foramen. The vertebral foramina of adjacent vertebrae are aligned to form a vertebral canal, through which the spinal sac, cord and nerve rootlets pass. The portion of the neural arch which extends posteriorly and acts to protect the spinal cord&#39;s posterior side is known as the lamina. Projecting from the posterior region of the neural arch is the spinous process. 
         [0005]    The intervertebral disc primarily serves as a mechanical cushion permitting controlled motion between vertebral segments of the axial skeleton. The normal disc is a unique, mixed structure, comprised of three component tissues: the nucleus pulpous (“nucleus”), the annulus fibrosus (“annulus”) and two vertebral end plates. The two vertebral end plates are composed of thin cartilage overlying a thin layer of hard, cortical bone which attaches to the spongy, richly vascular, cancellous bone of the vertebral body. The end plates thus act to attach adjacent vertebrae to the disc. 
         [0006]    The spinal disc and/or vertebral bodies may be displaced or damaged due to trauma, disease, degenerative defects, or wear over an extended period of time. One result of this displacement or damage to a spinal disc or vertebral body may be chronic back pain. A common procedure for treating damage or disease of the spinal disc or vertebral body may involve partial or complete removal of an intervertebral disc. An implant, which may be referred to as an interbody spacer, can be inserted into the cavity created where the intervertebral disc was removed to help maintain height of the spine and/or restore stability to the spine. An example of an interbody spacer that has been commonly used is a cage, which typically is packed with bone and/or bone-growth-inducing materials. However, there are drawbacks associated with conventional interbody spacers, such as cages and other designs. For instances, conventional interbody spacers may be too large and bulky for introduction into the disc space in a minimally invasive manner, such as may be utilized in a posterior approach. Further, these conventional interbody spacers may have inadequate surface area contact with the adjacent endplates if sized for introduction into the disc space in a minimally invasive manner. In addition, conventional interbody spacers designed for introduction into the disc space in a minimally invasive manner may lack sufficient space for packing of bone-growth-inducing material, thus potentially not promoting the desired graft between the adjacent endplates. 
         [0007]    Therefore, a need exists for an interbody spacer that can be introduced in a minimally manner that provides a desired amount of surface area contact with the adjacent endplates and has an increased space for packing of bone-growth-inducing material. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention relates to an expandable interbody spacer. The expandable interbody spacer may comprise a first jointed arm comprising a plurality of links pivotally coupled end to end. The expandable interbody spacer further may comprise a second jointed arm comprising a plurality of links pivotally coupled end to end. The first jointed arm and the second jointed arm may be interconnected at a proximal end of the expandable interbody spacer. The first jointed arm and the second jointed arm may be interconnected at a distal end of the expandable interbody spacer. The first jointed arm and the second jointed arm may each be configured to fold inward in opposite directions to place the expandable interbody spacer in an expanded position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present invention will be more readily understood with reference to the embodiments thereof illustrated in the attached drawing figures, in which: 
           [0010]      FIG. 1  is a top view of an expandable interbody spacer shown in a collapsed position in accordance with embodiments of the present invention; 
           [0011]      FIG. 2  is a side view of the expandable interbody spacer of  FIG. 1  shown in a collapsed position; 
           [0012]      FIG. 3  is a proximal end view of the expandable interbody spacer of  FIG. 1  shown in a collapsed position; 
           [0013]      FIG. 4  is a distal end view of the expandable interbody spacer of  FIG. 1  shown in a collapsed position; 
           [0014]      FIG. 5  is an exploded view of the expandable interbody spacer of  FIG. 1 ; 
           [0015]      FIG. 6  is a top view of the expandable interbody spacer of  FIG. 1  shown in an expanded position; 
           [0016]      FIG. 7  is a right side view of the expandable interbody spacer of  FIG. 1  shown in an expanded position; 
           [0017]      FIG. 8  is a left side view of the expandable interbody spacer of  FIG. 1  shown in an expanded position; 
           [0018]      FIG. 9  is a proximal end view of the expandable interbody spacer of  FIG. 1  shown in an expanded position; 
           [0019]      FIG. 10  is a distal end view of the expandable interbody spacer of  FIG. 1  shown in an expanded position; 
           [0020]      FIG. 11  is a view showing disc space between adjacent vertebrae in accordance with embodiments of the present invention; 
           [0021]      FIG. 12  is a view of a tool for insertion of an expandable interbody spacer in accordance with embodiments of the present invention; 
           [0022]      FIG. 13  is a view showing the tool of  FIG. 12  introducing an expandable interbody spacer into a disc space in a collapsed position in accordance with embodiments of the present invention; 
           [0023]      FIG. 14  is a view showing the tool of  FIG. 12  expanding an expandable interbody spacer in a disc space in accordance with embodiments of the present invention; 
           [0024]      FIG. 15  is a view showing a funnel for introduction of bone-growth-inducing material into a disc space in accordance with embodiments of the present invention; 
           [0025]      FIG. 16  is an exploded view of another embodiment of an expandable interbody spacer; 
           [0026]      FIG. 17  is a top view of another embodiment of an expandable interbody spacer shown in a collapsed position; 
           [0027]      FIG. 18  is a top view of the expandable interbody spacer of  FIG. 17  shown in an expanded position; 
           [0028]      FIG. 19  is an exploded view of the expandable interbody spacer of  FIG. 17 ; 
           [0029]      FIG. 20  is an exploded view of a link of a jointed arm of the expandable interbody spacer of  FIG. 17 ; 
           [0030]      FIG. 21  is a top view of another embodiment of an expandable interbody spacer shown in a collapsed position; 
           [0031]      FIG. 22  is a top view of the expandable interbody spacer of  FIG. 21  shown in an expanded position; 
           [0032]      FIG. 23  is a view of the expandable interbody spacer of  FIG. 21  shown in a disc space in a collapsed position; 
           [0033]      FIG. 24  is a view of the expandable interbody spacer of  FIG. 21  shown in a disc space in an expanded position; 
           [0034]      FIG. 25  is a top view of a tool shown engaging the expandable interbody spacer of  FIG. 21  in accordance with embodiments of the present invention; and 
           [0035]      FIG. 26  is a view showing the tool of  FIG. 24  expanding the expandable interbody spacer of  FIG. 24  in a disc space in accordance with embodiments of the present invention. 
       
    
    
       [0036]    Throughout the drawing figures, it should be understood that like numerals refer to like features and structures. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0037]    The preferred embodiments of the invention will now be described with reference to the attached drawing figures. The following detailed description of the invention is not intended to be illustrative of all embodiments. In describing preferred embodiments of the present invention, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. It is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. 
         [0038]    Referring to  FIGS. 1-10 , an expandable interbody spacer  10  is shown in accordance with embodiments of the present invention. In the illustrated embodiment, the expandable interbody spacer  10  has a proximal end  20  and a distal end  30 . The expandable interbody spacer  10  may include a first jointed arm  40  and a second jointed arm  50  positioned on either side of longitudinal axis  15  of the spacer  10 . The first and second jointed arms  40 ,  50  may be interconnected at the proximal end  20 , for example, by a proximal connection member  60 . The first and second jointed arms  40 ,  50  may be interconnected at the distal end  30 , for example, by a distal connection member  70 . The first and second jointed arms  40 ,  50  The expandable interbody spacer  10  may be made from a number of materials, including titanium, stainless steel, titanium alloys, non-titanium alloys, polymeric materials, plastic composites, polyether ether ketone (“PEEK”) plastic material, ceramic, elastic materials, and combinations thereof. While the expandable interbody spacer  10  may be used with a posterior, anterior, lateral, or combined approach to the surgical site, the spacer  10  may be particularly suited with a posterior approach. 
         [0039]    The first jointed arm  40  has a proximal end  80  and a distal end  90 . The proximal end  80  may be pivotally coupled to the proximal connection member  60 . The distal end  90  may be pivotally coupled to the distal connection member  70 . Any of a variety of different fasteners may be used to pivotally couple the proximal end  80  and the distal end  90  and the proximal connection member  60  and the distal connection member  70 , such as pins  100 , for example. In another embodiment (not illustrated), the connection may be a hinged connection. As illustrated, the first jointed arm  40  may comprise a plurality of links that are pivotally coupled to one another. In the illustrated embodiment, the first jointed arm  40  comprises first link  110 , second link  120 , and third link  130 . When the spacer  10  is in a collapsed position, the first link  110 , second link  120 , and third link may be generally axially aligned. As illustrated, the first link  110 , second link  120 , and third link  130  may be connected end to end. When the spacer  10  is in a collapsed position, the first link  110 , second link  120 , and third link  130  may be generally axially aligned. The first link  110  and the second link  120  may be pivotally coupled, and the second link  120  and the third link  130  may also be rotatably coupled. Any of a variety of different fasteners may be used to pivotally couple the links  110 ,  120 ,  130 , such as pins  100 , for example. In another embodiment (not illustrated), the coupling may be via a hinged connection. 
         [0040]    As best seen in  FIGS. 1 ,  5 - 7 ,  9 , and  10 , an upper surface  140  of the first jointed arm  40  may be defined by the links  110 ,  120 ,  130 . The upper surface  140  should allow for engagement of the first jointed arm  40  with one of the adjacent vertebral bodies. In some embodiments, the upper surface  140  may include texturing  150  to aid in gripping the adjacent vertebral bodies. Although not limited to the following, the texturing  150  can include teeth, ridges, friction-increasing elements, keels, or gripping or purchasing projections. 
         [0041]    As best seen in  FIGS. 7 ,  9 , and  10  a lower surface  160  of the first jointed arm  40  may be defined by the links  110 ,  120 ,  130 . The lower surface  160  should allow for engagement of the first jointed arm  40  with one of the adjacent vertebral bodies. In some embodiments, the lower surface  160  may include texturing  170  to aid in gripping the adjacent vertebral bodies. Although not limited to the following, the texturing  170  can include teeth, ridges, friction-increasing elements, keels, or gripping or purchasing projections. 
         [0042]    The second jointed arm  50  has a proximal end  180  and a distal end  190 . The proximal end  180  may be pivotally coupled to the distal connection member  70 . The distal end  190  may be pivotally coupled to the distal connection member  70 . Any of a variety of different fasteners may be used to pivotally couple the proximal end  180  and the distal end  190  and the proximal connection member  60  and the distal connection member  70 , such as pins  100 , for example. In another embodiment (not illustrated), the connection may be a hinged connection. As illustrated, the second jointed arm  50  may comprise a plurality of links that are pivotally coupled to one another. In the illustrated embodiment, the second jointed arm  50  comprises first link  200 , second link  210 , and third link  220 . When the spacer  10  is in a collapsed position, the first link  200 , second link  210 , and third link  220  may be generally axially aligned. As illustrated, the first link  200 , second link  210 , and third link  220  may be connected end to end. The first link  200  and the second link  210  may be pivotally coupled, and the second link  210  and the third link  220  may also be pivotally coupled. Any of a variety of different fasteners may be used to pivotally couple the links  200 ,  210 ,  220 , such as pins  100 , for example. In another embodiment (not illustrated), the coupling may be via a hinged connection. 
         [0043]    As best seen in  FIGS. 1 ,  2 ,  6 , and  8 - 10 , an upper surface  230  of the second jointed arm  50  may be defined by the links  200 ,  210 ,  220 . The upper surface  230  should allow for engagement of the second jointed arm  50  with one of the adjacent vertebral bodies. In some embodiments, the upper surface  230  may include texturing  240  to aid in gripping the adjacent vertebral bodies. Although not limited to the following, the texturing  240  can include teeth, ridges, friction-increasing elements, keels, or gripping or purchasing projections. 
         [0044]    As best seen in  FIGS. 8-10 , a lower surface  250  of the second jointed arm  50  may be defined by the links  200 ,  210 , and  220 . The lower surface  250  should allow for engagement of the second jointed arm  50  with one of the adjacent vertebral bodies. In some embodiments, the lower surface  250  may include texturing  260  to aid in gripping the adjacent vertebral bodies. Although not limited to the following, the texturing  260  can include teeth, ridges, friction-increasing elements, keels, or gripping or purchasing projections. 
         [0045]    With reference now to  FIGS. 3 ,  5 , and  9 , a bore  270  extends through proximal connection end  60 . The bore  270  may extend generally parallel to the longitudinal axis  12  (see  FIG. 1 ) of the spacer  10 . The first jointed arm  40  and the second jointed arm  50  may define a hollow interior portion (not shown) that extends axially through the spacer  10 . The bore  270  in the proximal connection end  60  may communicate with this hollow interior portion. As best shown on  FIG. 5 , the distal connection end  70  may include an opening  280 . As illustrated, the opening  280  may face inward and may not extend all the way through the distal connection  70 . In one embodiment, the opening  280  may be generally aligned with the bore  270  in the proximal connection end  60  such at a tool (e.g., tool  340  shown on  FIG. 12 ) inserted into the bore  270  may be received in the opening  280  for placement of the spacer  10  into a disc space and/or expansion of the spacer  10 . 
         [0046]      FIGS. 1-4  illustrate the expandable interbody spacer  10  in a collapsed position. In accordance with present embodiments, the expandable interbody spacer  10  may be laterally expanded to an expanded position.  FIGS. 6-10  illustrate the expandable interbody spacer  10  in an expanded position. In the expanded position, the first arm  40  and the second arm  50  have each been folded inward in opposite directions. For example, the proximal end  80  and the distal end  90  of the first arm  40  may be folded closer together. The links  110 ,  120 ,  130  should pivot with respect to one another when the first arm  40  is folded inward. The proximal end  80  should pivot at the proximal connection end  60 , and the distal end  90  should pivot at the distal connection end  70 . By way of further example, the proximal end  180  and the distal end  190  of the second arm  50  may also be folded together. The links  200 ,  210 ,  220  should pivot with respect to another when the second arm is folded inward. The proximal end  180  should pivot at proximal connection end  60 , and the distal end  190  should pivot at the distal connection end  70 . After placement in the expanded position, the expandable interbody spacer  10  can be secured in the expanded position to prevent collapse of the expandable interbody spacer  10  upon application of spacer. Any of a variety of different techniques may be used to secure the expandable interbody spacer  10 , including pins or other suitable locking mechanism, for example. 
         [0047]    As illustrated by  FIG. 6 , the first and second jointed arms  40 ,  50  define an interior cavity  290  when in an expanded position. The interior cavity  290  may be filled with a bone-growth-inducing material, such as bone material, bone-growth factors, or bone morphogenic proteins. As will be appreciated by those of ordinary skill in the art, the bone-growth-inducing material should induce the growth of bone material, thus promoting fusion of the adjacent vertebra. 
         [0048]    The expandable interbody spacer  10  may be sized to accommodate different applications, different procedures, implantation into different regions of the spine, or size of disc space. For example, the expandable interbody spacer  10  may have a width W 1  (as shown on  FIG. 1 ) prior to expansion of about 8 to about 22 and alternatively from about 10 to about 13. By way of further example, the expandable interbody spacer  10  may be expanded to a width W 2  (as shown on  FIG. 6 ) in a range of about 26 to about 42 and alternatively from about 16 to about 32. It should be understood that the width W 1  or W 2  whether prior to, or after, expansion generally refers to the width of the expandable interbody spacer  10  extending transverse to the longitudinal axis  12  of the spacer  10 . In general, the width W 2  of the expandable interbody spacer  10  after expansion should be greater than the width W 1  of the expandable interbody spacer  10  prior to expansion. 
         [0049]    In accordance with present embodiments, the expandable interbody spacer  10  may be used in the treatment of damage or disease of the vertebral column. In one embodiment, the expandable interbody spacer  10  may be inserted into a disc space between adjacent vertebrae in which the intervertebral disc has been partially or completely removed.  FIG. 11  illustrates a spinal segment  300  into which the expandable interbody spacer  10  (e.g.,  FIGS. 1-10 ) may be inserted. The spinal segment  300  includes adjacent vertebrae, identified by reference numbers  310  and  320 . Each of the adjacent vertebrae  310 ,  320  has a corresponding endplate  315 ,  325 . The disc space  330  is the space between the adjacent vertebrae  310 ,  320 .  FIG. 12  illustrates a tool  340  that may be used in the insertion of the expandable interbody spacer  10  into the disc space  330 . The tool  340  includes a shaft  350  having an elongated end portion  360  for coupling to the expandable interbody spacer  10 . The elongated end portion  360  has a distal tip  370 . 
         [0050]      FIGS. 13 and 14  illustrate introduction of an expandable interbody spacer  10  into the disc space  330  using tool  340 . For illustrative purposes, the upper vertebra  330  shown on  FIG. 11  has been removed from  FIGS. 13 and 14 . As illustrated, the spacer  10  may be secured to the tool  340 . For example, the elongated end portion  360  of the tool  340  may be disposed through the bore  270  (e.g., see  FIG. 5 ) in the proximal connection end  60  with the distal tip  370  (e.g., see  FIG. 12 ) of the end portion  360  secured in the opening  280  (e.g., see  FIG. 5 ) in the distal connection end  70 . As illustrated by  FIG. 13 , the tool  340  may introduce the spacer  10  into the disc space  330  through an access cannula  380 . After introduction into the disc space  330 , the spacer  10  may be laterally expanded. In accordance with present embodiments, the spacer  10  can be laterally expanded by folding the first arm  40  and the second arm  50  inward. By expanding laterally, the spacer  10  has an increased surface area contact with the endplate  325 . In addition, the spacer  10  may engage harder bone around the apophyseal ring. As previously mentioned, an interior cavity  290  should be formed in the spacer  10  when in the expanded position. The tool  340  may then be detached from the spacer  10  and removed from the cannula  380 . As illustrated by  FIG. 15 , a funnel  390  may then be placed on the cannula  380 . Bone-growth inducing material may then be placed into the interior cavity  290  through the cannula  380 . Because the spacer  10  has been laterally expanded, the interior cavity  290  should have a desirable amount of space for packing of the bone-growth-inducing material. 
         [0051]      FIG. 16  illustrates an expandable interbody spacer  10  in accordance with an alternative embodiment. In the illustrated embodiment, the expandable interbody spacer  10  comprises a first jointed arm  40  and a second jointed arm  50 . The first jointed arm  40  has a proximal end  80  and a distal end  90 . The first jointed arm  40  comprises a plurality of links  110 ,  120 ,  130  connected end to end, for example, by pins  100 . The first jointed arm  40  further may comprise washers  105  (e.g, PEEK washers) that may be disposed between the links  110 ,  120 ,  130  at their connections. The second jointed arm  50  has a proximal end  180  and a distal end  190 . The second jointed arm  50  comprises a plurality of links  200 ,  210 ,  220  connected end to end, for example, by pins  100 . The second jointed arm  50  further may comprise washers  105  (e.g, PEEK washers) that may be disposed between the links  200 ,  210 ,  220  at their connections. Washers  105  may also be disposed between the first arm  40  and the proximal connection member  60  and the distal connection member  70  at their respective connections. Washers  105  may also be disposed between the second arm  50  and the proximal connection member  60  and the distal connection member  70  at their respective connections. The washers  105  should have an interference fit to cause friction such that the spacer  10  may hold its shape in the entire range of the expanded implant. 
         [0052]    The proximal ends  80 ,  180  may be pivotally coupled, for example, by pin  100 , as shown on  FIG. 19 . The distal ends  90 ,  180  may also be pivotally coupled, for example, by pin  100 , as shown on  FIG. 19 . The first jointed arm  40  comprises first link  110  and third link  130 , the first link  110  and the third link  130  being pivotally coupled. In contrast to the first jointed arm  40  of  FIGS. 1-10 , there 
         [0053]    Referring now to  FIGS. 17-19 , an expandable interbody spacer  10  is illustrated in accordance with another embodiment of the present invention. In the illustrated embodiment, the expandable interbody spacer  10  comprises a first jointed arm  40  and a second jointed arm  50 . The first jointed arm  40  has a proximal end  80  and a distal end  90 . The second jointed arm  50  has a proximal end  180  and a distal end  190 . The proximal ends  80 ,  180  may be pivotally coupled, for example, by pin  100 , as shown on  FIG. 19 . The distal ends  90 ,  180  may also be pivotally coupled, for example, by pin  100 , as shown on  FIG. 19 . The first jointed arm  40  comprises first link  110  and third link  130 , the first link  110  and the third link  130  being pivotally coupled. In contrast to the first jointed arm  40  of  FIGS. 1-10 , there is no second link  120 . As shown by  FIG. 20 , the third link  130  may comprise a first link segment  400  and a second link segment  410 , which may be secured to one another by pins  420 , for example. First link segment  400  and second link segment  410  may also have a tongue-and-groove connection, for example a groove  430  in the first link segment  400  may receive a tongue  440  of the second link segment  410 . The second jointed arm comprises first link  200  and third link  220 , the first link  200  and the third link  220  being pivotally coupled. In contrast to the second joint arm  50  of  FIGS. 1-10 , there is no second link  210 . 
         [0054]    In accordance with present embodiments, lateral expansion of the expandable interbody spacer  10  of  FIGS. 17-19  may include folding the first arm  40  and the second arm  50  inward. For example, the proximal end  80  and the distal end  90  of the first arm  40  may be folded together, and the proximal end  180  and the distal end  190  of the second arm  50  may also be folded together. 
         [0055]    Referring now to  FIGS. 21 and 22 , an expandable interbody spacer  10  is illustrated in accordance with another embodiment of the present invention. In the illustrated embodiment, the expandable interbody spacer  10  has a proximal end  20  and a distal end  30 . The expandable interbody spacer  10  may include a first jointed arm  40  and a second jointed arm  50  positioned on either side of longitudinal axis  12  of the spacer  10 . As illustrated, the expandable interbody spacer  10  further may comprise an internal screw  450 . The internal screw  450  may comprise a head  460  and an elongated body  470 , which may extend generally parallel to the longitudinal axis  12  of the spacer  10 . In some embodiments, the internal screw  450  may extend from the proximal end  20  to the distal end  30  of the spacer  10 . In one embodiment, the elongated body  470  may be retractable. For example, the elongated body  470  may retract into the head  460 , as shown on  FIG. 22 . 
         [0056]    As illustrated by  FIGS. 23 and 24 , the spacer  10  may be introduced into the disc space  330 , wherein the spacer  10  can be laterally expanded. In accordance with present embodiments, the spacer  10  can be laterally expanded by folding the first arm  40  and the second arm  50  inward. In some embodiments, the elongated body  470  may be retracted into the head  460  to cause folding of the first arm  40  and the second arm  50  inward, as the first arm  40  and the second arm  50  are secured to the distal end  480  of the internal screw  450 . 
         [0057]      FIG. 25  shows attachment of a tool  490  to the expandable interbody spacer  10  of  FIGS. 22 and 23  in accordance with embodiments of the present invention. As illustrated, the tool  490  may have an attachment end  500 , which can be secured to the head  460  of the internal screw  450 . As shown by  FIG. 26 , the tool  40  can be used to introduce the spacer  10  into the disc space  330 , wherein the spacer  10  can be laterally expanded. 
         [0058]    While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations can be made thereto by those skilled in the art without departing from the scope of the invention as set forth in the claims.