Patent Publication Number: US-2011071637-A1

Title: System and methods for inserting a vertebral spacer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 10/923,499, filed on Aug. 20, 2004; which application is a continuation of U.S. patent application Ser. No. 09/947,851, filed on Sep. 6, 2001, now U.S. Pat. No. 6,824,565; which application claims the benefit of U.S. Provisional Patent Application No. 60/231,142, filed on Sep. 8, 2000. 
    
    
     INCORPORATION BY REFERENCE 
     The specifications of 10/923,499, filed Aug. 20, 2004; 09/947,851, filed Sep. 6, 2001; and 60/231,142, filed Sep. 8, 2000, are incorporated herein in their entirety, by this reference. 
     1. Field of Invention 
     The present invention generally relates to a vertebral spacer to be inserted into an intervertebral space, thereby supporting the spinal column of a patient. The present invention further relates to a system and methods for implanting the vertebral spacer into the spinal column and securing the spacer therein. 
     2. Background of the Invention 
     The spinal column, which is the central support to the vertebrate skeleton and a protective enclosure for the spinal cord, is a linear series of vertebral bones. Intervertebral discs separate and reduce friction between adjacent vertebrae and absorb compression forces applied to the spinal column. Spinal nerves that extend from each side of the spinal cord exit the column at intervertebral forama. 
     A typical vertebra comprises an anterior body, and a posterior arch that surrounds the spinal cord lying within the vertebral foramen formed by the arch. The muscles that flex the spine are attached to three processes extending from the posterior arch. On the upper surface of each vertebra in a standing human, are two superior articulated processes that oppose two inferior articulated processes extending from the lower surface of an adjacent vertebra. Facets on the opposing processes determine the range and direction of movement between adjacent vertebrae, hence the flexibility of the spinal column. 
     The intervertebral discs include the fibrillar cartilage of the anulus fibrosus, a fibrous ring, the center of which is filled with an elastic fibrogelatinous pulp that acts as a shock absorber. The outer third of the anulus fibrosus is innervated. The entire spinal column is united and strengthened by encapsulating ligaments. 
     Back pain is one of the most significant problems facing the workforce in the United States today. It is a leading cause of sickness-related absenteeism and is the main cause of disability for people aged between 19 and 45. Published reports suggest that the economic cost is significant, treatment alone exceeding $80 billion annually. Although acute back pain is common and typically treated with analgesics, chronic pain may demand surgery for effective treatment. 
     Back pain can occur from pinching or irritation of spinal nerves, compression of the spine, vertebral shifting relative to the spinal cord axis, and bone spur formation. The most common cause of disabling back pain, however, stems from trauma to a intervertebral disc, resulting from mechanical shock, stress, tumors or degenerative disease, which may impair functioning of the disc and limit spinal mobility. In many cases, the disc is permanently damaged and the preferred treatment becomes partial or total excision. 
     Another cause of back injury is herniation of the intervertebral disc, wherein the gelatinous fluid of the nucleus pulposus enters the vertebral canal and pressures the spinal cord. Again, surgery is often the only method available for permanent relief from pain or the neurological damage ensuing from the pressure of fluid on the spinal cord, and requires replacement of the damaged disc. 
     Traumatic injury to an intervertebral disc that is not removed will frequently promote scar tissue formation. Scar tissue is weaker than original healthy tissue so that the disc will progressively degenerate, lose water content, stiffen and become less effective as a shock absorber. Eventually, the disc may deform, herniate, or collapse, limiting flexibility of the spinal column at that position. The only option is for the intervertebral disc to be partially or totally removed. 
     When the disc is partially or completely removed, it is necessary to replace the excised material to prevent direct contact between hard bony surfaces of adjacent vertebrae. One vertebral spacer that may be inserted between adjacent vertebrae, according to U.S. Pat. No. 5,989,291 to Ralph et al., includes two opposing plates separated by a belleville washer or a modified belleville washer. The washer functions to provide a restorative force to mimic the natural functions of the disc of providing a shock absorber and mobility between adjacent vertebrae. However, mechanical devices intended to replicate intervertebral disc function have had only limited success. An alternative approach is a “cage” that maintains the space usually occupied by the disc to prevent the vertebrae from collapsing and impinging the nerve roots. 
     Spinal fusion may be used to restrict motion occurring between two vertebrae due to spinal segmental instability. Fusing the vertebrae together, however, reduces the mechanical back pain by preventing the now immobile vertebrae from impinging on the spinal nerve. The disadvantage of such spacers is that stability is created at the expense of spinal flexibility. 
     Surgical procedures for replacing intervertebral disc material, rather than the fusing of the vertebrae, have included anterior approaches and posterior approaches to the spinal column. The posterior approach (from the back of the patient) encounters the spinous process, superior articular process, and the inferior articular process that must be removed before insertion of the disc replacement material into the intervertebral space. Excessive removal of the bony process triggers further degradation and impediment of the normal movement of the spine. The anterior approach to the spinal column is complicated by the internal organs that must be bypassed or circumvented to access the vertebrae. 
     Many intervertebral spacers require preparation of the surfaces of the adjacent vertebrae to accommodate the spacer, causing significant tissue and bone trauma. For example, chiseling or drilling of the vertebral surface may be required to prepare a receiving slot. They may also require screwing the spacer into the intervertebral space, making installation difficult and increasing trauma to the vertebral tissue. Many spacers include complex geometries and are costly to manufacture. Examples of such geometrically complex spacers are described in U.S. Pat. No. 5,609,636 to Kohrs et al., U.S. Pat. No. 5,780,919 to Zdeblick et al., U.S. Pat. No. 5,865,848 to Baker and U.S. Pat. No. 5,776,196 to Matsuzaki et al. Many of these complex spacers may require screwing the spacer into the intervertebral space, thereby making installation difficult and traumatic to the vertebral tissue. 
     SUMMARY OF THE INVENTION 
     There is a need for a vertebral spacer having a simple geometry that is easily insertable into an intervertebral space while causing minimal trauma to the surface of the vertebrae as well as the bony processes thereof. The present invention provides a vertebral spacer having a simple geometry for supporting adjacent vertebrae after excision, at least partially or wholly, of an intervertebral disc. The spacer includes a body having a lower surface and an upper surface. The lower surface will be supported by a lower vertebra; the upper surface supports the adjacent upper vertebra. The body of the vertebral spacer of the present invention, therefore, provides support between the two adjacent vertebrae and to the spinal column. 
     The body of the vertebral spacer of the present invention additionally has an anterior face and a posterior face extending from the lower surface. The height of the anterior face of the body may be less than, or greater than, the height of the posterior face to maintain the curvature of the spine when the vertebral spacer is inserted between two vertebrae. The body of the vertebral spacer also includes at least one guiding groove suitable for engaging with an insertion tool for delivering the vertebral spacer to an intervertebral space. 
     The present invention further provides a system for delivering a vertebral spacer to the spinal column of a patient, comprising an insertion tool with a channel; (b) an optional guiding tool for directing the insertion tool to a selected point of insertion of a vertebral spacer; (c) a pusher; (d) a vertebral spacer slideably disposed in the channel of the insertion tool; and (e) a cutting tool. The cutting tool can be slid into the channel of the insertion tool providing that the pusher and the vertebral spacer are not therein. 
     The channel of the insertion tool is configured to slideably accept any of a vertebral spacer, a pusher, a vertebral spacer , or a cutting tool. The insertion tool further comprises a spacer guide or a plurality of spacer guides for engagement with a first guiding groove or a second guiding groove of a vertebral spacer. 
     In one embodiment of the insertion tool the spacer guide is a flange extending from the channel. In another embodiment, the spacer guide is two opposing flanges configured to slideably engage with a first guiding groove and a second guiding groove, respectively. 
     In another embodiment of the insertion tool, the spacer guide is at least one rib longitudinally placed on the inner surface of the channel of the insertion tool. 
     Other embodiments of the insertion tool of the present invention include spacer guides that may be, but are not limited to, a segmented longitudinal rib, or a linear series of protrusions, also on the inner surface of the channel. 
     The present invention further provides a method for delivering a vertebral spacer to a patient, comprising the steps of inserting the insertion tool into an intervertebral space of the spinal column of a patient, engaging at least one guiding groove of a vertebral spacer with a space guide of the insertion tool, sliding a pusher into the channel of the insertion tool, advancing the pusher and thereby pushing the vertebral spacer into the intervertebral space and removing the pusher and the insertion tool from the patient. 
     The method of the present invention may further comprise the optional step of inserting a guiding tool into an intervertebral space for directing the insertion tool into the intervertebral space. The insertion tool may be slid along the guide tool to a selected position suitable for insertion of a vertebral spacer in the intervertebral space. The guide tool is then extracted from the insertion tool leaving the insertion tool inserted between adjacent vertebrae. 
     The cutting tool is optionally slid along the channel of the insertion tool to engage a vertebra and generally is used to chisel at least one vertebral space receiving slot in the vertebrae. The cutting tool is removed from the patient by sliding the cutting tool back through the channel of the insertion tool. A vertebral spacer may then be slideably engaged with the insertion tool, with a space guide on the insertion tool engaging with a guiding groove of the vertebral spacer. The pusher may be engaged and advanced along the channel, thereby delivering the vertebral spacer into the vertebral spacer receiving slot (or receiving slots) in the adjacent vertebrae. It is also contemplated that a vertebral spacer receiving slot may not be cut in the adjacent vertebrae and that the inserted vertebral spacer optionally may contact only the uncut surface of the vertebrae. 
     One embodiment of the method of the present invention comprises the additional step of delivering a hardening biocompatible composition to the vertebral spacer. The hardening biocompatible composition may be used, for example, to bond the vertebral spacer to an adjacent vertebra or be an osteogenic composition to promote bone growth from the adjacent vertebrae into the vertebral spacer. The hardening biocompatible composition can be, for example, an organic polymer, a mineral composition such as a hydroxyapatite-based composition, methyl methacrylate, or the like, or a combination thereof. A hydroxyapatite-based composition is especially useful in the context of the present invention for promoting osteocyte growth and bone deposition. 
     Various objects, features, and advantages of the invention will become more apparent upon review of the detailed description set forth below when taken in conjunction with the accompanying drawing figures, which are briefly described as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1A  illustrates an embodiment of the vertebral spacer according to the present invention having a first guiding groove and a second guiding groove. 
         FIG. 1B  illustrates an embodiment of the vertebral spacer according to the present invention having protrusions on the upper surface thereof. 
         FIG. 2A  illustrates an embodiment of the vertebral spacer according to the present invention wherein a section dissected from a femur bone is contained within a partial metallic sheath. 
         FIG. 2B  illustrates an embodiment of the vertebral spacer according to the present invention wherein a section dissected from a femur bone is contained within a partial metallic sheath and having angular protuberances on the metallic sheath. 
         FIG. 3  illustrates another embodiment of the vertebral spacer according to the present invention having two slots extending from the upper surface thereof. 
         FIG. 4  is an end elevation of the embodiment of the vertebral spacer shown in  FIG. 3 . 
         FIG. 5  is a side elevation of the embodiment of the vertebral spacer shown in  FIG. 3 . 
         FIG. 6  is a horizontal elevation showing the bottom surface of the embodiment of the vertebral spacer shown in  FIG. 3 . Positions of the slots relative to the second guiding groove are indicated by dashed lines. 
         FIG. 7  illustrates another embodiment of the vertebral spacer according to the present invention wherein slots extending from the upper surface thereof accommodate bone material therein. 
         FIG. 8  illustrates another embodiment of the vertebral spacer comprising alternate layers of bone, a biocompatible material, and a linking pin. 
         FIG. 9  illustrates another embodiment of a layered vertebral spacer according to the present invention wherein the outermost layers are bone. 
         FIGS. 10-12  illustrate the sectioning of a femur to give at least one vertebral spacer according to the present invention.  FIG. 10  shows the sectioning planes for the excision of a section of a femur. 
         FIG. 11  shows a cross-sectional view of an excised section of a femur with minimal portions of the femur shown in cross-hatch trimmed away to give two vertebral spacers.  FIG. 12  shows the cross-sectional view of two vertebral spacers cut from a femoral section. 
         FIG. 13  shows an end elevation of a vertebral spacer according to the present invention excised from a femur and having two guiding grooves therein. 
         FIG. 14  shows a side elevation of a vertebral spacer according to the present invention excised from a femur. 
         FIGS. 15 and 16  illustrate an embodiment of the vertebral spacer of the present invention excised from a femur wherein the femur medullary cavity not bisected. 
         FIG. 17  is a perspective view of a vertebral spacer according to the present invention excised from a femur. 
         FIG. 18  is an end elevation of the vertebral spacer illustrated in  FIG. 17 . 
         FIG. 19  is a perspective view of another vertebral spacer according to the present invention cut from the same section of femur as the spacer in  FIG. 17 . 
         FIG. 20  shows a top elevation of a vertebral spacer according to the present invention cut from a femur section. 
         FIG. 21  shows a bottom elevation of a vertebral spacer according to the present invention cut from a femur section. 
         FIG. 22  illustrates a perspective view of a vertebral spacer according to the present invention cut from a femur section and having a plurality of bores therein. 
         FIGS. 23-28  illustrate perspective cross-sectional views of embodiments of the insertion tool according to the present invention.  FIG. 23  shows an embodiment of the insertion tool having a flange thereon.  FIG. 24  shows an embodiment of the insertion tool having two flanges.  FIG. 25  shows an embodiment of the insertion tool having a rib thereon.  FIG. 26  shows an embodiment of the insertion tool having two ribs.  FIG. 27  shows an embodiment of the insertion tool having a plurality of longitudinal ribs.  FIG. 28  shows an embodiment of the insertion tool having protrusions. 
         FIG. 29  illustrates a perspective view of the system for delivering a vertebral spacer to a patient according to the present invention wherein the vertebral spacer engages two flanges on the insertion tool. 
         FIG. 30  illustrates a perspective view of the system for delivering a vertebral spacer to a patient according to the present invention wherein the vertebral spacer engages two ribs on the insertion tool. 
         FIG. 31  illustrates a perspective view of an embodiment of the system for delivering a vertebral spacer to a patient wherein the insertion tool has two flanges. 
         FIG. 32  illustrates a perspective view of an embodiment of the system for delivering a vertebral spacer to a patient wherein the insertion tool has two ribs. 
         FIGS. 33-35  illustrate the assembly of an embodiment of the system for delivering a vertebral spacer to a patient.  FIG. 33  shows a vertebral spacer engaging an insertion tool according to the present invention.  FIG. 34  illustrates the system wherein the distal end of a pusher is configured to accept the vertebral spacer.  FIG. 35  illustrates the direction of delivery of the vertebral spacer to an intervertebral space by the insertion tool and the pusher therein. 
         FIG. 36  illustrates a vertical cross-sectional view of an embodiment of the system for delivery of a vertebral spacer to a patient according to the present invention. 
         FIG. 37  illustrates a vertical cross-sectional view of another embodiment of the system for delivery of a vertebral spacer to a patient according to the present invention. 
         FIG. 38  illustrates the cutting of a vertebral spacer receiving slot by an embodiment of the cutting tool according to the present invention. 
         FIG. 39  is a side-elevation of an embodiment of the cutting tool and insertion tool according to the present invention. 
         FIG. 40  illustrates an end-elevation of an embodiment of the cutting tool according to the present invention. 
         FIG. 41  is a perspective view of an embodiment of the cutting tool and the insertion tool according to the present invention. 
         FIGS. 42-45  illustrate the delivery of a vertebral spacer to an intervertebral space according to the methods of the present invention.  FIG. 42  illustrates the placing of an insertion tool into an intervertebral space by using a guiding tool.  FIG. 43  shows the rotation of the insertion tool within the intervertebral space after extraction of the guiding tool.  FIG. 44  illustrates the formation of a vertebral spacer receiving slot by the cutting tool.  FIG. 45  illustrates the delivery of the vertebral spacer into the intervertebral space and the vertebral spacer receiving slot. 
         FIG. 46  is a perspective view showing an embodiment of the vertebral spacer according to the present invention in situ in an intervertebral space of a patient. 
         FIG. 47  is an overhead view showing two vertebral spacers formed from a femur on a vertebral surface. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A full and enabling disclosure of the present invention, including the best mode known to the inventor of carrying out the invention, is set forth more particularly in the remainder of the specification, including reference to the accompanying drawings, wherein like reference numerals designate corresponding parts throughout several figures. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in the limiting sense. 
     One aspect of the present invention is a vertebral spacer for insertion between two adjacent vertebrae  20 , thereby maintaining the intervertebral space  23  and preventing compression of the spinal cord therein. Various embodiments of the vertebral spacer  10  in accordance with the present invention are shown in  FIGS. 1A-22 . The vertebral spacer  10  of the present invention is useful to replace an intervertebral disc  21  that has degenerated due to traumatic injury, vertebral displacement, or disease, such as, for example, autoimmune disease or rheumatoid arthritis or any other pathological condition of the spinal column that may injure or shift the intervertebral disc. The vertebral spacer  10  of the present invention provides support to the vertebrae  20  and maintains separation between vertebrae while also preserving the natural curvature of the spine. 
     The vertebral spacer  10  of the present invention may have a plurality of surfaces, including a lower surface  15  and an upper surface  16 , with the lower surface  15  having an anterior face  13  and a posterior face  14  extending therefrom, as shown in  FIG. 1A . The anterior face  13  may be directed towards the inner body cavity of a patient, and the posterior face  14  may be directed towards the dorsal surface of the patient. The vertebral spacer  10  can be configured such that the height of the anterior face  13  is less than the height of the posterior face  14 , as is illustrated, for example, in  FIG. 1A . The difference in the height of the opposing anterior  13  and posterior  14  faces of the vertebral spacer  10  of the present invention, so that the lower surface  15  and the upper surface  16  are non-parallel, is useful to preserve the natural curvature of the spinal column. The vertebral spacer  10  of the present invention further comprises a first guiding groove  17  in the upper surface  16  or the lower surface  15  of the vertebral spacer  10 . The vertebral spacer  10 , as contemplated by the present invention, may also have an optional second guiding groove  18  in the upper surface  16  or the lower surface  15  not having the first guiding groove  17  therein. 
     It is contemplated that the vertebral spacer  10  of the present invention may be of any biocompatible or physiologically inert material or combination of such materials having the mechanical strength capable of maintaining the intervertebral space  23  ( FIG. 46 ) between two adjacent vertebrae  20 . Examples of such materials include bone, such as bone sections from the femur, titanium, titanium alloy, stainless steel, chrome cobalt, and polymeric materials such as methyl methacrylate (MMA), urethane, polyacetal and the like. The material of the vertebral spacer  10  may, however, also have a degree of resilience and thereby tolerate a degree of compression. Such materials may include, but are not limited to, polymers such as carbon fiber reinforced polymer such as PEEK (polyetherether ketone), polycarbonate, polypropylene, polyethylene, polyamide and silicone-based polymers. 
     It is further contemplated that the vertebral spacer  10  of the present invention may comprise a bone core  12  such as a femur and a sheath  35  as shown in  FIG. 2 . 
     In one embodiment, the sheath  35  is metallic, such as a tungsten sheath. In another embodiment the sheath comprises a biocompatible polymer. In one embodiment, shown in  FIG. 2B , the metallic sheath  35  has angular protrusions  34  thereon. 
     The vertebral spacer  10  of the present invention may have any conformation that will allow the spacer  10  to be positioned in an intervertebral space  23  between adjacent vertebrae  20  and which will maintain an intervertebral space  23  and the natural curvature of a spinal column when in the desired position. Referring to  FIGS. 1A-22 , exemplary geometric cross-sections that may be applied to the vertebral spacer  10  of the present invention include, but are not limited to, a rectangular cross-section or a trapezoidal cross-section. 
     As shown in  FIGS. 1B and 2B , the upper surface  16 , and optionally the lower surface, of the vertebral spacer  10  can also include at least one protrusion  34  for frictionally engaging a vertebrae  20  as disclosed in U.S. patent application Ser. No. ______ incorporated herein by reference in its entirety. An exemplary embodiment of the protrusions  34  of the present invention traversing the upper surface  16  of the vertebral spacer  10  are illustrated in  FIG. 1B . In another embodiment of the vertebral spacer  10  of the present invention, as shown in  FIG. 2B , the protrusions are located on a metallic sheath  35  encapsulating a bone core  12 . The protrusions  34  may have any suitable geometric configuration that will allow the vertebral spacer  10  of the present invention to be secured to adjacent vertebrae, including having a triangular, rounded, or rectangular cross-section and the like, or any combination thereof. The protrusions may be elongated as shown in  FIG. 1B , or any other shape such as square or circular protrusions or irregular non-elongated protrusions. 
     When the vertebral spacer  10  comprises a section of a femur and wherein the femur medullary cavity  19  connects the anterior face  13  and the posterior face  14  of the vertebral spacer  10 , as shown in  FIG. 2 , the hardening biocompatible composition may be delivered to the portion of the femur medullary cavity  19 . With the alternative embodiments of the vertebral spacer  10  having at least one slot  11  extending from the upper surface  16  or lower surface  15 , the hardening biocompatible composition may be delivered to the slots  11  thereof. One embodiment of the method of the present invention, therefore, further comprises the step of delivering a hardening biocompatible composition to the vertebral spacer  10 . The hardening biocompatible composition may be used, for example, to bond the vertebral spacer  10  to an adjacent vertebra or be an osteogenic composition to promote bone growth from the adjacent vertebrae into the vertebral spacer  10 . The hardening biocompatible composition may be, for example, an organic polymer, a mineral composition such as a hydroxyapatite-based compositions, methyl methacrylate or a combination thereof. A hydroxyapatite-based composition is especially useful in the context of the present invention for promoting osteocyte growth and bone deposition. 
     The direction of insertion of the vertebral spacer  10  by the methods of the present invention can be selected by the surgeon according to the needs of the patient. The anterior face  13  of the vertebral spacer  10 , for example, may be positioned relative to the spine to maintain a desired curvature thereof, as shown in  FIG. 46 . The vertebral spacer  10  may be inserted posteriorly as shown, for example in  FIG. 46 , anteriorly, or laterally, relative to the spinal column. Once inserted into a desired position in the intervertebral space  23 , as shown in  FIG. 46 , the lower surface  15  and the upper surface  16  of the vertebral spacer  10  are substantially contacting the adjacent vertebrae  20 . For example, the lower surface  15  of the vertebral spacer  10  may contact the lower vertebra  20 , and the upper surface  16  may support the adjacent upper vertebra  20 . Optional protrusions  34  extending from the upper surface  16  as shown, for example, in  FIG. 1B , and/or the lower surface  15  can increase the frictional resistance between the vertebral spacer  10  and the adjacent vertebrae  20 . As shown in  FIG. 46 , the vertebral spacer  10  of the present invention can support adjacent vertebrae  20  after the partial or total surgical removal of an intervertebral disc  21 , thereby preventing collapse and/or compression of the spine in this region that might otherwise lead to severe neurological damage. 
     In another embodiment of the vertebral spacer  10  of the present invention, at least one slot  11  may be formed in the upper surface  16  and extend towards, but not connecting with, the opposing lower surface  15 , as shown in  FIGS. 3-6 . Alternatively, the at least one slot  11  may be formed in the lower surface  15  and extend towards the upper surface  16 . 
     In still another embodiment of the vertebral spacer  10  of the present invention, the at least one slot  11  has a bone core  12  disposed therein, as shown in  FIG. 7 . Alternatively, a hardening biocompatible composition may be deposited in the at least one slot  11 , wherein the hardening biocompatible composition generally comprises an osteogenic compound such as, for example, hydroxyapatite. 
     In another embodiment of the vertebral spacer  10  of the present invention, shown in  FIGS. 8 and 9 , the spacer  10  comprises a plurality of layers, wherein at least one layer is a bone core  12 . The plurality of layers may be bonded by any suitable method such as an adhesive, screws, bolts, a linking pin, or the like, and which will hold the layers immobile relative to each other. In one embodiment of the vertebral spacer  10  of the present invention, as shown in  FIG. 9 , may be bonded by at least one pin  9 . In another embodiment of the vertebral spacer  10 , the plurality of layers may be bonded by two pins positioned to prevent movement of the layers relative to each other. The bonding method will not impede installation of the vertebral spacer  10  into the intervertebral space  23  ( FIG. 46 ) of a patient. The alternate layers may have bone cores  12  as inner layers as shown in  FIGS. 7 and 8 , or as the outermost layers of the vertebral spacer  10 , as shown in  FIG. 9 . 
     Referring now to  FIGS. 10-22 , in another embodiment of the vertebral spacer  10  of the present invention, the vertebral spacer  10  is formed from a femoral section  24  taken from the shaft  22  of a femur, as shown in  FIG. 10 . The femoral section  24 , having a central femur medullary cavity  19  therein, may be trimmed as shown in  FIGS. 11 ,  12 ,  15  and  16  to yield at least one vertebral spacer  10 . Each vertebral spacer  10  obtained from a femur shaft  22  will have at least a portion of the femur medullary cavity  19  connecting the upper  16  and lower  15  surfaces of the vertebral spacer  10 . The indented portion of the femur medullary cavity  19  is useful to partially surround a spinal cord when the vertebral spacer  10  is positioned within an intervertebral space, thereby allowing the vertebral spacer  10  to be positioned closer to the spinal cord than would be possible if the cavity  19  were not present. The vertebral spacer  10  of the present invention, when excised from a femur shaft  22  ( FIG. 10 ) also has a first guiding groove  17 , and optionally, a second guiding groove  18 , in the upper  16  and/or lower  15  surfaces respectively of the vertebral spacer  10 , as shown in  FIGS. 11-22 . 
     Referring now to  FIG. 22 , the vertebral spacer  10  of the present invention may further include a bore  46 , or a plurality of bores  46 , extending from the upper surface  16  and/or the lower surface  15  of the vertebral spacer  10 . Bony or other tissue growth from adjacent vertebrae that extends into the bore  46 , or plurality of bores  46 , of the vertebral spacer  10  of the present invention may bond the vertebrae and the vertebral spacer  10 . The bony growth will, therefore, effectively fuse the adjacent vertebrae. It is further contemplated that a tissue growth factor or an osteogenic material may be inserted into the bores to increase the bony growth and, therefore, the rate of this fusion. Suitable growth factors include, but are not limited to, growth hormones, steroids, tissue growth factors and the like. 
     Another aspect of the present invention is a system for delivering a vertebral spacer  10  to the spinal column of a patient, generally illustrated in  FIGS. 24-41 . The system for delivering the vertebral spacer comprises (a) an insertion tool  60  for delivering the vertebral spacer  10  to the spinal column of a patient, wherein the insertion tool  60  has a channel  61  and an inner surface  62  as shown in  FIGS. 24-28 ; (b) an optional guiding tool  80 ; (c) a pusher  63  (as in  FIGS. 31-37 ) having a distal end  65  slideably disposable in the channel  61  of the insertion tool  60 ; (d) a vertebral spacer  10  slideably disposable in the channel  61  of the insertion tool  60 ; and (e) a cutting tool  70  ( FIGS. 38-41 ) having a shaft  72  with a distal end  74  and a proximal end  75 , and a cutting head  71  secured to the distal end  74  of the shaft  72 . 
     The channel  61  of the insertion tool  60  of the system of the present invention generally is configured to slideably accept any of the various vertebral spacers  10 , according to the present invention, a pusher  63  and/or a cutting tool  70 . The insertion tool  60  further comprises at least one spacer guide  66  for slideably engaging with a first guiding groove  17  or a second guiding groove  18  of a vertebral spacer  10 . 
     Referring now to  FIGS. 23-28 , in one embodiment of the insertion tool  60  of the present invention, as shown in  FIG. 23 , the spacer guide  66  is a flange extending along an outside edge of the channel  61 . In another embodiment of the insertion tool  60  of the present invention, as shown in  FIG. 24 , the spacer guide  66  is two opposing flanges along the upper and lower outside or distal side edges of the insertion tool  10  configured to slideably engage with a first guiding groove  17  ( FIGS. 1 ,  3 - 9 ,  11 - 14 ) and a second guiding groove  18  of a vertebral spacer  10 . 
     In still another embodiment of the insertion tool  60  of the present invention as shown in  FIGS. 25 and 26 , the spacer guide  66  is formed as one or more ribs longitudinally disposed on an inner surface  62  of the channel  61 . 
     In other embodiments of the insertion tool  60  of the present invention, the spacer guide  66  may be formed by at least one segmented longitudinal rib disposed on the inner surface  62  of the channel  61 , as shown in  FIG. 27 , or a linear series of spaced protrusions, also disposed on the inner surface  62  of the channel  61 , as shown in  FIG. 28 . It is to be understood, however, that any configuration of spacer guides  66  may be used by the insertion tool  60  that will allow a vertebral spacer to be slideably engaged with the insertion tool  60  and not resist insertion of the vertebral spacer into the spinal column of a patient. 
     As shown in  FIGS. 29-35 , the spacer guide  66 , or a plurality of guides  66 , may slideably engage the first  17  and optional second  18  guiding groove with at least a portion of the vertebral spacer  10  positioned externally to the channel  61 , as illustrated in  FIGS. 29 and 31 . 
     The present invention also provides an optional guide tool  80  that can be slideably disposed in the channel  61  of the insertion tool  60 . The elongated optional guide tool can be inserted into an intervertebral space  23  as indicated in  FIGS. 42-43 , to a position selected by a surgeon for guiding the insertion tool  60  to the same selected position. 
     As shown in  FIGS. 31-32 ,  34 - 37 , and  45 , the system for delivery of a vertebral spacer  10  to the spinal column of a patient further comprises a pusher  63  having a distal end  65  for contacting a vertebral spacer  10  disposed in the channel  61 . It is contemplated that the pusher  63  can be slideably engaged in the channel  61  of the insertion tool  60  and is suitable for enabling a surgeon to push a vertebral spacer  10  along the channel  61 , out of the insertion tool  60  and into an intervertebral space  23 . 
     In one embodiment of the pusher of the present invention as illustrated in  FIGS. 31 and 32 , the distal end  65  may be substantially parallel to the posterior face  14  of the vertebral spacer  10 . This orientation is especially useful for inserting a vertebral spacer  10  of the present invention in the lumbar region of a spinal column. It is to be understood, however, that the vertebral spacer  10  may be inserted in the insertion tool  60  in the opposite orientation for insertion in another region of the spine where reverse curvature to that of the lumbar region is to be maintained. In other embodiments of the present invention such as shown, for example, in  FIGS. 34 ,  35  and  37 , the configuration of the distal end  65  of the pusher  63  may be defined by the anterior face  13  and the upper surface  16  of the vertebral spacer  10 . 
     As illustrated in  FIGS. 38-41 , the system for the delivery of a vertebral spacer  10  to the spinal column of a patient further provides a cutting tool  70  suitable for cutting a vertebral spacer receiving slot  78  into a vertebra  20 . The cutting tool  70  of the present invention has a shaft  72  with a distal end  74  and a proximal end  75 . A cutting head  71  is connected to the distal end  74  of the shaft  72  of the cutting tool  70 . In one embodiment of the cutting tool  70  of the present invention, a striking head  73  is disposed on the proximal end  75  of the shaft  72 . 
     The cutting head  71  of the cutting tool  70  may be an integral configuration of the distal end  74  of the shaft  72 , or connected to the distal end  74  of the shaft  72 . In one embodiment of the cutting tool  70  of the present invention, the cutting head  71  is connected to the shaft by an attachment member  76  which may be, for example, a threaded attachment member  76 , as shown in  FIGS. 39 and 40 . The cutting head  71  will be capable of being slideably disposed within the channel  61  of the insertion tool  60  providing that the pusher  63  and the vertebral spacer  10  are not disposed therein 
     Another aspect of the present invention is a method for delivering a vertebral spacer  10  to a patient using the system of the present invention comprising the insertion tool  60 , an optional guide tool  80 , the vertebral spacer  10 , the pusher  63  and the cutting tool  70 . Such a method is generally illustrated in  FIGS. 42-45  and comprises the steps of inserting the insertion tool  60  into an intervertebral space  23  of the spinal column of a patient ( FIG. 42 ), rotating the insertion tool  60  in the intervertebral space  23  ( FIG. 43 ), cutting a vertebral spacer receiving slot  78  ( FIG. 44 ), and engaging the first guiding groove  17 , and optionally a second guiding groove  18 , of a vertebral spacer  10  with a space guide  66  of the insertion tool  60 . The vertebral spacer  10  is pushed into the intervertebral space  23  by slideably disposing a pusher  63  into the channel  61  of the insertion tool  60 , and advancing the pusher  63  ( FIG. 45 ). The pusher  63  and the insertion tool  60  are then removed from the patient. 
     The insertion tool  60  further optionally may be directed into the selected position within the intervertebral space  23  by the guide tool  80  that may be inserted by the surgeon into the intervertebral space  23 . The method of the present invention, therefore, further comprises the optional step of inserting a guiding tool  80  into an intervertebral space  23 . 
     The insertion tool  60  may then be slid along the guide tool  80  until the insertion tool  60  is at the selected position for insertion of a vertebral spacer  10  in the intervertebral space  23 . The guide tool  80  is then removed from the channel  61  of the insertion tool  60 , as shown in  FIG. 42 , leaving the insertion tool  60  inserted between adjacent vertebrae  20 . Alternatively, the guide tool  80  may remain in the insertion tool  60  while the insertion tool  60  is rotated in the intervertebral space  23 , thereby providing torsional strength to the insertion tool  60 . The insertion tool  60  may be inserted into the intervertebral space  23  with the channel  61  facing a vertebra  20 , as shown in  FIG. 42 . The insertion tool  60  may then be rotated so that the open channel  61  of the tool  60  is not facing a vertebra  20 , as shown in  FIG. 43 . 
     As shown in  FIG. 44 , the cutting tool  70  is optionally slid along the channel  61  of the insertion tool  60  to engage a vertebra  20  and to chisel a vertebral space receiving slot  78  in the vertebrae  20 . Alternatively, two vertebral spacer receiving slots  78  may be cut in opposing faces of adjacent vertebrae  20 . The striking head  73  of the cutting tool  70  may be struck with a striking tool  77  to increase the cutting action of the cutting head  71 . 
     As shown in  FIG. 45 , the cutting tool  70  is removed from the patient by slideably withdrawing the cutting tool  70  back through the channel  61  of the insertion tool  60 . A vertebral spacer  10  according to the present invention may then be slideably engaged with the insertion tool  60 , wherein at least one space guide  66  on the insertion tool  60  engages with a first guiding groove  17  and optionally a second guiding groove  18  of the vertebral spacer  10 . The pusher  63  may then be slideably engaged with the channel  61  and contacted with the vertebral spacer  10 . The pusher  63  is advanced along the channel  61  of the insertion tool  60  thereby pushing the vertebral spacer  10  into the vertebral spacer receiving slot  78  or receiving slots  78  in the adjacent vertebrae  20 . It is also contemplated, however, that a vertebral spacer receiving slot  80  may not be cut in the adjacent vertebrae  20  and that the inserted vertebral spacer  10  may optionally contact the uncut surface of the vertebrae  20 . 
     It is to be understood that the methods of the present invention for the delivery of a vertebral spacer  10  to an intervertebral space  23  may also be used to deliver two vertebral spacers  10 , as shown in  FIG. 47 , it is further understood that a hardening biocompatible composition may be delivered between the vertebral spacers, thereby forming a larger effective spacer and optionally promoting bone growth to secure the vertebral spacers  10  to the vertebrae. 
     Yet another aspect of the present invention is a kit for delivering a vertebral spacer to the spinal column of a patient, comprising an insertion tool for delivering a vertebral spacer to the spinal column of a patient and having a channel having an inner surface, a pusher having a distal end is slideably disposable in the channel of the insertion tool, a vertebral spacer slideably disposable in the channel of the insertion tool, a cutting tool having a shaft with a distal end and a proximal end, and a cutting head secured to the distal end of the shaft, wherein the cutting tool is slideably disposable in the insertion tool providing that the pusher and the vertebral spacer are not disposed therein. Instructions for the use of the system and its various components to deliver a vertebral spacer to the spinal column of a patient also generally are included or provided. 
     The kit of the present invention further can include an optional guiding tool configured to slideably engage the channel of the insertion device, and instructions for the operation thereof. 
     With respect to the above description, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly, and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawing and described in the specification are intended to be encompassed by the present invention. Further, the various components of the embodiments of the invention may be interchanged to produce further embodiments and these further embodiments are intended to be encompassed by the present invention. 
     Although the invention has been described in detail for the purpose of illustration, it is understood that such detail is solely for that purpose, and variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention which is defined by the following claims.