Abstract:
This invention is directed to improved methods and devices to attach arthroplasty devices, particularly the spine, distract the disc space, machine the disc space to improve the fit between ADRs and the vertebrae, to hold and remove ADRs, and to facilitate spinal fusion for a failed ADR surgery. One aspect of the invention places anchor devices in the spine during a first operation. Spinal devices are connected to the anchoring devices during a second procedure. The second procedure is generally performed months after the insertion of the anchoring devices. The time between the two procedures allows bone to grow into the anchoring devices. Minimal forces are exerted on the anchoring devices between the procedures. Other embodiments are described where a previously implanted ADR having a pair of opposing endplates is immobilized using a device the attached to the endplates, fits between the endplates, or both.

Description:
REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority from U.S. Provisional Patent Application Ser. No. 60/608,401, filed Sep. 9, 2004, the entire content of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates generally to surgical methods and apparatus and in particular to methods and apparatus for preventing movement through artificial disc replacements.  
       BACKGROUND OF THE INVENTION  
       [0003]     A small percent of patients will continue to experience low back pain (LBP) following insertion of Artificial Disc Replacements (ADR). Surgeons often fuse the vertebrae immediately above and below the ADR in an attempt to decrease patients&#39; LBP. Patients&#39; spine may be fused from a posterior approach to the spine. Pedicle screws and other types of spinal instrumentation may be used to facilitate fusion. Many surgeons believe a posterior spinal fusion is inadequate following ADR insertion. They believe continued movement through the ADR will prevent a successful fusion. Thus many surgeons advocate removal of the ADR and spinal fusion with interbody cages and pedicle screws. All surgeons agree that removal of ADRs, particularly in the lumbar spine, is dangerous procedure. The great vessels including the vena cava, aorta, and iliac vessels may become adherent to the spine following insertion of ADRs. The fragile vessels may be torn during revision surgery. Tears of the great vessels may be life threatening.  
         [0004]     Eighty-five percent of the population will experience low back pain at some point. Fortunately, the majority of people recover from their back pain with a combination of benign neglect, rest, exercise, medication, physical therapy, or chiropractic care. A small percent of the population will suffer chronic low back pain. The cost of treatment of patients with spinal disorders plus the patient&#39;s lost productivity is estimated at 25 to 100 billion dollars annually.  
         [0005]     Seven cervical (neck), 12 thoracic, and 5 lumbar (low back) vertebrae form the normal human spine. Intervertebral discs reside between adjacent vertebra with two exceptions. First, the articulation between the first two cervical vertebrae does not contain a disc. Second, a disc lies between the last lumbar vertebra and the sacrum (a portion of the pelvis).  
         [0006]     The spine supports the body, and protects the spinal cord and nerves. The vertebrae of the spine are also supported by ligaments, tendons, and muscles which allow movement (flexion, extension, lateral bending, and rotation). Motion between vertebrae occurs through the disc and two facet joints. The disc lies in the front or anterior portion of the spine. The facet joints lie laterally on either side of the posterior portion of the spine.  
         [0007]     The human intervertebral disc is an oval to kidney bean shaped structure of variable size depending on the location in the spine. The outer portion of the disc is known as the annulus fibrosis. The annulus is formed of 10 to 60 fibrous bands. The fibers in the bands alternate their direction of orientation by 30 degrees between each band. The orientation serves to control vertebral motion (one half of the bands tighten to check motion when the vertebra above or below the disc are turned in either direction). The annulus contains the nucleus. The nucleus pulpous serves to transmit and dampen axial loads. A high water content (70-80 percent) assists the nucleus in this function. The water content has a diurnal variation. The nucleus imbibes water while a person lies recumbent. Activity squeezes fluid from the disc. Nuclear material removed from the body and placed into water will imbibe water swelling to several times its normal size. The nucleus comprises roughly 50 percent of the entire disc. The nucleus contains cells (chondrocytes and fibrocytes) and proteoglycans (chondroitin sulfate and keratin sulfate). The cell density in the nucleus is on the order of 4,000 cells per micro liter.  
         [0008]     Interestingly, the adult disc is the largest avascular structure in the human body. Given the lack of vascularity, the nucleus is not exposed to the body&#39;s immune system. Most cells in the nucleus obtain their nutrition and fluid exchange through diffusion from small blood vessels in adjacent vertebra.  
         [0009]     The disc changes with aging. As a person ages the water content of the disc falls from approximately 85 percent at birth to 70 percent in the elderly. The ratio of chondroitin sulfate to keratin sulfate decreases with age. The ratio of chondroitin 6 sulfate to chondroitin 4 sulfate increases with age. The distinction between the annulus and the nucleus decreases with age. These changes are known as disc degeneration. Generally disc degeneration is painless.  
         [0010]     Premature or accelerated disc degeneration is known as degenerative disc disease. A large portion of patients suffering from chronic low back pain are thought to have this condition. As the disc degenerates, the nucleus and annulus functions are compromised.  
         [0011]     The nucleus becomes thinner and less able to handle compression loads. The annulus fibers become redundant as the nucleus shrinks. The redundant annular fibers are less effective in controlling vertebral motion. The disc pathology can result in: 1) bulging of the annulus into the spinal cord or nerves; 2) narrowing of the space between the vertebra where the nerves exit; 3) tears of the annulus as abnormal loads are transmitted to the annulus and the annulus is subjected to excessive motion between vertebra; and 4) disc herniation or extrusion of the nucleus through complete annular tears.  
         [0012]     Current surgical treatments of disc degeneration include procedures to remove the nucleus or a portion of the nucleus; lumbar discectomy falls in this category. A second group of procedures destroy nuclear material; Chymopapin (an enzyme) injection, laser discectomy, and thermal therapy (heat treatment to denature proteins) fall in this category. Spinal fusion procedures either remove the disc or the disc&#39;s function by connecting two or more vertebra together with bone. Perhaps the most promising solution, prosthetic disc replacement, offers many advantages. The prosthetic disc attempts to eliminate a patient&#39;s pain while preserving the disc&#39;s function.  
         [0013]     Prior-art techniques connect stabilization and arthroplasty devices to the anchoring components during a single procedure. The prior-art technique subjects the anchoring devices to excessive forces. Excessive forces on the anchoring devices frequently cause movement between the vertebrae and the anchoring components. Movement between the anchoring component and the vertebrae inhibits bone ingrowth. Thus, despite advances in this field, the need remains for further improvements in the way in which prosthetic components are incorporated into the disc space, and in materials to ensure strength and longevity.  
       SUMMARY OF THE INVENTION  
       [0014]     This invention is directed to improved methods and devices to attach arthroplasty devices, particularly the spine, distract the disc space, machine the disc space to improve the fit between ADRs and the vertebrae, to hold and remove ADRs, and to facilitate spinal fusion for a failed ADR surgery.  
         [0015]     One aspect of the invention places anchor devices in the spine during a first operation. Spinal devices are connected to the anchoring devices during a second procedure. The second procedure is generally performed months after the insertion of the anchoring devices. The time between the two procedures allows bone to grow into the anchoring devices. Minimal forces are exerted on the anchoring devices between the procedures.  
         [0016]     The anchor devices used in the novel invention are manufactured to promote bone ingrowth in the preferred embodiment of the device. For example, the anchoring devices may be covered with titanium plasma spray or hydroxyapatite. Alternatively, the anchoring devices could be made of tantalum (Zimmer). The anchoring devices are preferably placed with a minimally invasive surgical (MIS) procedure.  
         [0017]     Other embodiments are described where a previously implanted ADR having a pair of opposing endplates is immobilized using a device the attached to the endplates, fits between the endplates, or both.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1A  shows a sagittal cross section of the spine and screws used to anchor a spinal arthroplasty device;  
         [0019]      FIG. 1B  shows a sagittal cross-section of the spine and a dynamic stabilization device;  
         [0020]      FIG. 2  shows a sagittal cross-section of the spine, anchoring components, and a facet replacement device;  
         [0021]      FIG. 3A  shows a coronal cross-section of the spine and an artificial disc replacement (ADR);  
         [0022]      FIG. 3B  shows a sagittal cross-section of the spine and the embodiment of the invention shown in  FIG. 3A ;  
         [0023]      FIG. 3C  shows an anterior view of the spine and an exploded view of the ADR and staple shown in  FIG. 3A ;  
         [0024]      FIG. 3D  shows an inferior view of the inferior ADR component;  
         [0025]      FIG. 3E  shows a sagittal cross-section of the ADR and staple shown in  FIG. 3B ;  
         [0026]      FIG. 3F  shows a coronal cross-section of the spine and an alternative embodiment of the invention;  
         [0027]      FIG. 4A  is an anterior view of the spine, an exploded view of an alternative embodiment of an ADR incorporating novel spikes;  
         [0028]      FIG. 4B  shows a sagittal cross-section of the spine and the embodiment of the invention shown in  FIG. 4A ;  
         [0029]      FIG. 4C  shows a coronal cross-section of the spine and the embodiment of the invention shown in  FIG. 4A ;  
         [0030]      FIG. 4D  shows a coronal cross-section of the spine and an alternative embodiment of the invention shown in  FIG. 4C ;  
         [0031]      FIG. 5A  shows an anterior view of a novel cutting and distraction device;  
         [0032]      FIG. 5B  shows a lateral view of the embodiment of the device shown in  FIG. 5A ;  
         [0033]      FIG. 5C  shows a lateral view of the device shown in  FIG. 5B ;  
         [0034]      FIG. 5D  shows an exploded lateral view of the embodiment of the invention shown in  FIG. 5C ;  
         [0035]      FIG. 5E  shows a view of the top of the cutting guide shown in  FIG. 5A ;  
         [0036]      FIG. 5F  shows a view of the top of an alternative cutting guide;  
         [0037]      FIG. 5G  shows a sagittal cross-section of the spine and a portion of the device shown in  FIG. 5C ;  
         [0038]      FIG. 5H  shows a sagittal cross-section of the spine, a portion of the device shown in  FIG. 5G ;  
         [0039]      FIG. 5I  shows a sagittal cross-section of the spine, a portion of the device shown in  FIG. 5G , a prior-art distraction device, a portion of a saw and saw blade;  
         [0040]      FIG. 5J  shows a superior view of the cutting guide, a portion of the holding tool, and the saw shown in  FIG. 5I ;  
         [0041]      FIG. 6A  shows a lateral view of the spine and a novel guide;  
         [0042]      FIG. 6B  shows a partial sagittal view of the spine and the novel guide shown in  FIG. 6A ;  
         [0043]      FIG. 6C  shows a partial sagittal view of the spine after insertion of the distraction screws;  
         [0044]      FIG. 6D  shows a partial sagittal view of the spine, distraction screws, and a novel distraction apparatus;  
         [0045]      FIG. 6E  shows partial sagittal view of the spine, the embodiment of the invention drawn in  FIG. 6D , an ADR, and a novel ADR holder;  
         [0046]      FIG. 7A  shows superior view of an ADR and an alternative embodiment of the present invention;  
         [0047]      FIG. 7B  shows a superior view of a novel “slap hammer” that may be used with the holder shown in  FIG. 7A  to extract the ADR;  
         [0048]      FIG. 7C  shows a view of the assembled devices shown in  FIGS. 7A and 7B ;  
         [0049]      FIG. 7D  shows an exploded lateral view of an ADR and a portion of the pliers-like device shown in  FIG. 7A ;  
         [0050]      FIG. 7E  shows a lateral view of an assembled ADR and holder;  
         [0051]      FIG. 7F  shows a lateral view of the spine and the ADR and holder shown in  FIG. 7E ;  
         [0052]      FIG. 8A  shows a lateral view of the cutting guide shown in  FIG. 5F ;  
         [0053]      FIG. 8B  shows a coronal cross-section of the cutting guide shown in  FIG. 8A ;  
         [0054]      FIG. 8C  shows a lateral view of the spine, and the embodiment of the device drawn in  FIG. 8B ;  
         [0055]      FIG. 9A  shows an anterior view of a novel component used to prevent movement of ADRs;  
         [0056]      FIG. 9B  shows a lateral view of the device shown in  FIG. 9A ;  
         [0057]      FIG. 9C  shows a lateral view of an ADR and the device shown in  FIG. 9B ;  
         [0058]      FIG. 9D  shows an exploded lateral view of the embodiment of the invention drawn in  FIG. 9C ;  
         [0059]      FIG. 9E  shows a partial sagittal view of the spine, the embodiment of the invention drawn in  FIG. 9C , and plates and screws;  
         [0060]      FIG. 10A  shows a lateral view of a novel ADR;  
         [0061]      FIG. 10B  shows a lateral view of an alternative embodiment;  
         [0062]      FIG. 11A  shows an anterior view of an alternative embodiment of the ADR shown in  FIG. 10B ;  
         [0063]      FIG. 11B  shows a lateral view of the ADR drawn in  FIG. 11A ;  
         [0064]      FIG. 11C  shows an anterior view of the spine;  
         [0065]      FIG. 12  shows a superior view of a pliers-like holder that fits into triangular or other shaped depressions in the sides of the ADR;  
         [0066]      FIG. 13A  shows a lateral view of an alternative distractor/cutting guide according to the present invention;  
         [0067]      FIG. 13B  shows a lateral view of the spine and the device;  
         [0068]      FIG. 13C  shows a partial sagittal cross-section of the spine and the device shown in  FIG. 13B ;  
         [0069]      FIG. 13D  shows a lateral view of the spine;  
         [0070]      FIG. 14A  shows a lateral view of the spine and an alternative distractor/guide;  
         [0071]      FIG. 14B  shows a partial sagittal cross-section of the spine and the device shown in  FIG. 14A ;  
         [0072]      FIG. 14C  shows a view of the top of a portion of the guide shown in  FIG. 14A ;  
         [0073]      FIG. 14D  shows a view of the top of the guide shown in  FIG. 14C ;  
         [0074]      FIG. 15A  shows an anterior view of an alternative ADR including screws used to attach the ADR to the vertebra above and below the ADR;  
         [0075]      FIG. 15B  shows a lateral view of the ADR shown in  FIG. 15B ;  
         [0076]      FIG. 16A  shows an anterior view of an alternative embodiment of the present invention;  
         [0077]      FIG. 16B  shows a lateral view of the spine and the embodiment of the ADR shown in  FIG. 16A ;  
         [0078]      FIG. 16C  shows a lateral view of the spine and an alternative embodiment of the present invention;  
         [0079]      FIG. 17A  shows a view of the bottom of the upper ADR endplate (ADR EP) shown in  FIG. 16A ;  
         [0080]      FIG. 17B  shows a view of the top of the lower ADR EP shown in  FIG. 16B ;  
         [0081]      FIG. 17C  shows a coronal cross-section of the ADR shown in  FIG. 16A ;  
         [0082]      FIG. 17D  shows a lateral view of an instrument used to align the ADR EPs shown in  FIG. 17C ;  
         [0083]      FIG. 17E  shows a coronal cross-section of the ADR shown in  FIG. 17C  and the alignment tool drawn in  FIG. 17D ;  
         [0084]      FIG. 18  shows an anterior view of an alternative embodiment of the present invention;  
         [0085]      FIG. 19A  shows an exploded lateral view of an ADR and alternative embodiment of the present invention related to  FIG. 9D ;  
         [0086]      FIG. 19B  shows a lateral view of the embodiment of the invention shown in  FIG. 19A  and an ADR;  
         [0087]      FIG. 19C  shows a posterior view of the device and an ADR;  
         [0088]      FIG. 20  shows the view of the top of an ADR and embodiments of the invention shown in  FIG. 19A ;  
         [0089]      FIG. 21  shows a posterior view of an ADR having holes to receive the embodiment of the invention shown in  FIG. 19A ;  
         [0090]      FIG. 22  shows a lateral view of an alternative embodiment of the invention and a sagittal cross-section through a novel ADR;  
         [0091]      FIG. 23A  shows an exploded lateral view of an alternative embodiment of the present invention;  
         [0092]      FIG. 23B  shows a lateral view of the embodiment of the invention shown in  FIG. 23A  and an ADR;  
         [0093]      FIG. 24A  shows an exploded lateral view of an alternative embodiment of the invention shown in  FIG. 23A ;  
         [0094]      FIG. 24B  shows a lateral view of the embodiment of the invention shown in  FIG. 24A  and a novel ADR;  
         [0095]      FIG. 24C  shows a view of the top of the embodiment of the ADR shown in  FIG. 24B ;  
         [0096]      FIG. 24D  shows a posterior view of the embodiment of the invention shown in  FIG. 24C ;  
         [0097]      FIG. 25A  shows an exploded lateral view of an alternative embodiment of the present invention;  
         [0098]      FIG. 25B  shows a sagittal cross-section of the embodiment of the present invention shown in  FIG. 25A  and an ADR;  
         [0099]      FIG. 26A  shows an exploded lateral view of an alternative embodiment of the present invention;  
         [0100]      FIG. 26B  shows a lateral view of the embodiment of the invention drawn in  FIG. 26A  and a sagittal cross-section through an ADR;  
         [0101]      FIG. 27A  shows an exploded lateral view of an alternative embodiment of the present invention and an ADR;  
         [0102]      FIG. 27B  shows a lateral view of the embodiment of the invention shown in  FIG. 27A ;  
         [0103]      FIG. 27C  shows a posterior view of the embodiment of the invention shown in  FIG. 27B ;  
         [0104]      FIG. 27D  shows a partial posterior view of an alternative embodiment of the present invention related to that shown in  FIG. 27C ;  
         [0105]      FIG. 28A  shows an exploded lateral view of an alternative embodiment of the present invention;  
         [0106]      FIG. 28B  shows an exploded view of the top of the embodiment of the present invention shown in  FIG. 28A ;  
         [0107]      FIG. 28C  shows a lateral view of the embodiment of the invention shown in  FIG. 28B  and an ADR;  
         [0108]      FIG. 28D  shows a lateral view of the embodiment of the invention shown in  FIG. 28C ;  
         [0109]      FIG. 28E  shows a view of the top of an ADR EP and the embodiment of the present invention shown in  FIG. 28B ;  
         [0110]      FIG. 28F  shows a lateral view of the embodiment of the invention shown in  FIG. 28E ;  
         [0111]      FIG. 29A  shows a lateral view of an alternative embodiment of the present invention;  
         [0112]      FIG. 29B  shows a lateral view of the embodiment of the invention shown in  FIG. 29A ;  
         [0113]      FIG. 29C  shows a sagittal cross-section of the embodiment of the invention shown in  FIG. 29B ;  
         [0114]      FIG. 30A  shows a lateral view of the tip of an alternative embodiment of the present invention;  
         [0115]      FIG. 30B  shows a lateral view of the embodiment of the invention shown in  FIG. 30A ;  
         [0116]      FIG. 30C  shows a lateral view of the embodiment of the invention shown in  FIG. 30B  and an ADR;  
         [0117]      FIG. 31A  shows a lateral view of an alternative embodiment of the device shown in  FIG. 25A ;  
         [0118]      FIG. 31B  shows a view of the top of the inferior ADR EP shown in  FIG. 31A ;  
         [0119]      FIG. 31C  shows a view of the top of the inferior ADR EP shown in  FIG. 31B ;  
         [0120]      FIG. 32A  shows a view of the articulating side of the ADR EP shown in  FIG. 27A ;  
         [0121]      FIG. 32B  shows a view of the articulating side of an alternative embodiment of the invention shown in  FIG. 32A ;  
         [0122]      FIG. 32C  shows a view of the articulating side of an alternative embodiment of the present invention;  
         [0123]      FIG. 32D  shows a view of the articulating side of an alternative embodiment of the invention shown in  FIG. 32C ;  
         [0124]      FIG. 33  shows a lateral view of an ADR and an alternative embodiment of the present invention;  
         [0125]      FIG. 34A  shows a lateral view of an alternative embodiment of the present invention;  
         [0126]      FIG. 34B  shows a lateral view of the embodiment of the invention shown in  FIG. 34A ;  
         [0127]      FIG. 34C  shows a lateral view of an ADR and the embodiment of the invention shown in  FIG. 34B ;  
         [0128]      FIG. 35  shows the view of the top of an alternative embodiment of the invention shown in  FIG. 27A ;  
         [0129]      FIG. 36A  shows an oblique view of an alternative embodiment of the invention shown in  FIG. 19A ;  
         [0130]      FIG. 36B  shows a view of the posterior aspect of an alternative embodiment of the ADR shown in  FIG. 5A  of co-pending U.S. patent application Ser. No. 10/741,290, the entire content of which is incorporated herein by reference;  
         [0131]      FIG. 36C  shows a view of the posterior aspect of the embodiment of the ADR shown in  FIG. 36B  and the posterior aspect of the embodiment of the invention drawn in  FIG. 36A ; and  
         [0132]      FIG. 36D  shows a sagittal cross section through the embodiment of the ADR drawn in  FIG. 36B . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0133]      FIG. 1A  is a sagittal cross section of the spine and screws  102 ,  104  used to anchor a spinal arthroplasty device (not shown). The screws are partially contained in the pedicles of the vertebrae. The screws, or other anchoring devices, could be placed in other areas of the vertebrae.  FIG. 1B  is a sagittal cross section of the spine and a dynamic stabilization device  110 . A suitable device is taught in my co-pending U.S. patent application Ser. No. 10/412,896, the entire content of which is incorporated herein by reference. The dynamic stabilization device may be connected to the pedicle screws during a second operation several months after inserting screws  102 , 104 .  
         [0134]      FIG. 2  is a sagittal cross section of the spine, anchoring components, and a facet replacement device  202  attached to the anchoring components during a second procedure after inserting the anchoring components.  
         [0135]      FIG. 3A  is a coronal cross section of the spine and an artificial disc replacement (ADR)  302 . The inferior ADR component  304  is attached to the inferior vertebra  306  with a novel staple  308 . The holes in the ADR force the arms of the staple to converge as the staple is driven into the ADR. Alternatively, the holes in the ADR could force the arms of the staple to diverge as the staple is driven into the ADR. The novel attachment device does not project anterior to the spine. Prior-art cervical ADRs attach the ADRs to the front of the spine. Devices that extend unto the anterior surface of the cervical spine place pressure on the esophagus. The staple may be made of a shape memory material such as Nitinol.  FIG. 3B  is a sagittal cross section of the spine and the embodiment of the invention drawn in  FIG. 3A  showing how the arms of the staple course through the endplate of the vertebra below the ADR.  
         [0136]      FIG. 3C  is an anterior view of the spine and an exploded view of the ADR and staple drawn in  FIG. 3A .  FIG. 3D  is an inferior view of the inferior ADR component. The arms of the staple are seen projecting from holes in the ADR.  FIG. 3E  is a sagittal cross section of the ADR and staple drawn in  FIG. 3B . The holes in the ADR force the arms of the staple to bend inferiorly as the staple is driven into the ADR.  FIG. 3F  is a coronal cross section of the spine and an alternative embodiment of the invention, wherein both ADR components are attached to the vertebrae with staples.  
         [0137]      FIG. 4A  is an anterior view of the spine, an exploded view of an alternative embodiment of an ADR incorporating novel spikes  402 ,  404  used to attach the ADR to the vertebrae. For example, the proximal end of the spikes could be threaded into threaded holes in the ADR. A flexible drill could be used to drill pilot holes for the modular spikes.  FIG. 4B  is a sagittal cross section of the spine and the embodiment of the invention drawn in  FIG. 4A .  
         [0138]      FIG. 4C  is a coronal cross section of the spine and the embodiment of the invention drawn in  FIG. 4A . The drawing illustrates a novel method of inserting the ADR  180  degrees to the method used in  FIG. 4A . The novel method allows the insertion of spikes into the vertebra above or below the ADR. The lower ADR component  404  is held in the disc space by the upper ADR component. A convexity from one ADR component fits into a concavity in the other ADR component. The coupling between the ADR components prevents one ADR component from independently extruding from the disc space.  FIG. 4D  is a coronal cross section of the spine and an alternative embodiment of the invention drawn in  FIG. 4C . The modular spikes diverge but may converge.  
         [0139]      FIG. 5A  is an anterior view of a novel cutting and distraction device  500  used to prepare the disc space for an ADR. The areas  502 ,  504  represent slots in the device.  FIG. 5B  is a lateral view of the embodiment of the device drawn in  FIG. 5A .  FIG. 5C  is a lateral view of the device drawn in  FIG. 5B  and a tool  520  to hold the device. Projections  522 ,  524  from the holding tool fit into the slots of the cutting guide.  FIG. 5D  is an exploded lateral view of the embodiment of the invention drawn in  FIG. 5C .  FIG. 5E  is a view of the top of the cutting guide drawn in  FIG. 5A .  FIG. 5F  is a view of the top of an alternative cutting guide which has walls  530 ,  532  along the sides of the guide.  
         [0140]      FIG. 5G  is a sagittal cross section of the spine and a portion of the device drawn in  FIG. 5C . The cutting guide  500  and holding tool  520  have been impacted into the disc space. The wedge shape of the assembled device separates the vertebrae. Prior-art distraction screws  540 ,  542  are shown in the anterior portion of the spine.  
         [0141]      FIG. 5H  is a sagittal cross section of the spine, a portion of the device drawn in  FIG. 5G , and a prior-art distraction apparatus  550 . The superior component of the holding tool has been removed. The prior art distraction apparatus is used to maintain distraction of the disc space after the superior component of the holding tool has been removed. The prior-art distraction device fits over the distraction screws drawn in  FIG. 5G .  
         [0142]      FIG. 5I  is a sagittal cross section of the spine, a portion of the device drawn in  FIG. 5G , a prior-art distraction device, a portion of a saw  560  and saw blade  562 . The saw blade fits into the slot in the cutting guide. The projection  564  from the posterior portion of the cutting guide helps maintain distraction of the disc space and prevents the saw blade from entering the spinal canal.  FIG. 5J  is a superior view of the cutting guide, a portion of the holding tool, and the saw drawn in  FIG. 5I .  
         [0143]      FIG. 6A  is a lateral view of the spine and a novel guide  602  used to align the prior-art distraction screws drawn in  FIG. 5G . The guide  602  assures the distraction screws are placed parallel to one another.  FIG. 6B  is a partial sagittal view of the spine and the novel guide drawn in  FIG. 6A . Distraction screws  604 ,  606  can be seen coursing through the guide and into the spine.  FIG. 6C  is a partial sagittal view of the spine after insertion of the distraction screws.  
         [0144]      FIG. 6D  is a partial sagittal view of the spine, distraction screws, and a novel distraction apparatus  610 . The sleeves of the distraction apparatus diverge as the sleeves approach the body of the apparatus. The novel shape of the distraction apparatus force the spine into a lordotic position as the sleeves are placed over the distraction screws.  
         [0145]      FIG. 6E  is partial sagittal view of the spine, the embodiment of the invention drawn in  FIG. 6D , an ADR  620 , and a novel ADR holder  622 . The novel ADR holder has a projection  624  that cooperates with the anterior portion of the spine to assure proper placement of the ADR. For example, the projection could assure the ADR is recessed  2 mm into the disc space. Alternatively, the projection could assure the front portion of the ADR is flush with the anterior surface of the spine. The projection also prevents inadvertent insertion of the ADR into the spinal canal.  
         [0146]      FIG. 7A  is superior view of an ADR and an alternative embodiment of the invention providing pliers-like holder  702  used to grasp the side of an ADR  704 . The novel holder may also have a component that cooperates with the anterior surface of the spine.  FIG. 7B  is a superior view of a novel “slap hammer” that may be used with the holder drawn in  FIG. 7A  to extract the ADR. The portion  710  slides along the shaft  712  of the device.  FIG. 7C  is a view of the assembled devices drawn in  FIGS. 7A and 7B . The hook  720  of the slap hammer device fits into the axilla of the ADR holder. A nut  722  on the holder is advanced to hold the two tools together.  
         [0147]      FIG. 7D  is an exploded lateral view of an ADR  730  and a portion of the pliers-like device drawn in  FIG. 7A . Arms from the holder attach to both ADR components. Projections from the holder fit into holes in the ADR. The drawing illustrates use of round and square holes  740 ,  742  and a projection  744 .  FIG. 7E  is lateral view of an assembled ADR and holder. The holding tool holds the ADR components in a wedge shape.  FIG. 7F  is lateral view of the spine and the ADR and holder drawn in  FIG. 7E . The ADR has been impacted into the disc space.  
         [0148]      FIG. 8A  is lateral view of the cutting guide drawn in  FIG. 5F .  FIG. 8B  is a coronal cross section of the cutting guide drawn in  FIG. 8A , a saw blade  802 , and a portion of the holding tool  804  drawn in  FIG. 5C . The walls along the side of the cutting guide prevent the saw blade from cutting too lateral in the disc space. The walls of the cutting guide also help maintain distraction of the disc space.  FIG. 8C  is lateral view of the spine, and the embodiment of the device drawn in  FIG. 8B .  
         [0149]      FIG. 9A  is an anterior view of a novel component  902  used to prevent movement of ADRs.  FIG. 9B  is a lateral view of the device drawn in  FIG. 9A .  FIG. 9C  is a lateral view of an ADR and the device drawn in  FIG. 9B . The modular device  902  is attached to the front of an ADR.  FIG. 9D  is an exploded lateral view of the embodiment of the invention drawn in  FIG. 9C .  
         [0150]      FIG. 9E  is a partial sagittal view of the spine, the embodiment of the invention drawn in  FIG. 9C , and plates and screws. The novel invention is used to immobilize the spine after ADR insertion. For example, the device may be used in conjunction with other spinal fixation devices  990  to achieve a spinal fusion.  
         [0151]      FIG. 10A  is a lateral view of a novel ADR, wherein the posterior portion of the superior ADR component has been beveled or rounded at  1002  to better fit patients&#39; anatomy. For example, the novel ADR shape fits the cervical disc space better than prior-art ADRs.  FIG. 10B  is a lateral view of an alternative embodiment wherein the posterior portion  1004  of the inferior ADR component has been beveled or rounded. The novel shape fits the lumbar disc space better than prior-art ADRs.  
         [0152]      FIG. 11A  is an anterior view of an alternative embodiment of the ADR drawn in  FIG. 10B  wherein both ADR components  1102 ,  1104  have holes that accept a single screw or spike.  FIG. 11B  is a lateral view of the ADR drawn in  FIG. 11A . Screws  1106 ,  1108  have been inserted into the ADR. The screws are attached to the ADR. The screws preferably diverge to hold the ADR in the disc space.  FIG. 11C  is an anterior view of the spine showing how the screws or spikes are offset to avoid impingement between adjacent screws or adjacent ADR endplates.  
         [0153]      FIG. 12  is a superior view of a pliers-like holder that fits into triangular or other shaped depressions in the sides of the ADR  1212 . The posterior portion  1220  of the ADR may be tapered to facilitate insertion into the disc space.  
         [0154]      FIG. 13A  is a lateral view of an alternative distractor/cutting guide according to the invention.  FIG. 13B  is a lateral view of the spine and the device. The handle  1302  of the guide has been folded inferiorly to allow insertion of a saw  1304 . The saw blade  1306  fits through a slot in the anterior portion of the guide.  FIG. 13C  is a partial sagittal cross section of the spine and the device drawn in  FIG. 13B . The saw is used to remove a portion of the vertebra superior to the ADR. Saw blades may be provided in various lengths in accordance with the level of the spine or other physical considerations. Note how the saw impinges against the front of the guide to limit the depth of saw blade insertion.  FIG. 13D  is a lateral view of the spine. The dotted line represents the portion of the superior vertebra that is cut from the superior vertebra.  
         [0155]      FIG. 14A  is a lateral view of the spine and an alternative distractor/guide  1402  which is limited to the front portion of the disc space.  FIG. 14B  is a partial sagittal cross section of the spine and the device drawn in  FIG. 14A . The drawing illustrates the use of a saw to remove a portion of the vertebra superior to the ADR.  FIG. 14C  is view of the top of a portion of the guide drawn in  FIG. 14A .  FIG. 14D  is a view of the top of the guide drawn in  FIG. 14C . A saw blade  1404  has been inserted through the slot in the front of the guide.  
         [0156]      FIG. 15A  is an anterior view of an alternative ADR including screws used to attach the ADR to the vertebra above  1502 ,  1504  and below  1506  the ADR. The screws are connected to the ADR by hinged plates as described in my co-pending application, U.S. Ser. No. 60/538,179. The invention teaches the use of a single screw to hold one of the ADR endplates.  FIG. 15B  is a lateral view of the ADR drawn in  FIG. 15B .  
         [0157]      FIG. 16A  is an anterior view of an alternative embodiment wherein a single screw is used in each ADR component.  FIG. 16B  is a lateral view of the spine and the embodiment of the ADR drawn in  FIG. 16A . The screws  1602 ,  1604  pass through a angled portion of the ADR. The angled portion of the ADR courses between the vertical anterior surface of the ADR and the horizontal intradiscal portion of the ADR.  FIG. 16C  is a lateral view of the spine and an alternative embodiment which does not extend forward of the vertebral bodies  1610 ,  1612 .  
         [0158]      FIG. 17A  is a view of the bottom of the upper ADR Endplate (ADR EP) drawn in  FIG. 16A . The area  1702  represents a concave articulating surface in the upper plate. The area  1704  represents a hole the ADR. The hole cooperates with a tool that aligns the ADR in the disc space.  FIG. 17B  is a view of the top of the lower ADR EP drawn in  FIG. 16B . The area  1710  represents a convex articulating surface in the lower plate.  FIG. 17C  is a coronal cross section of the ADR drawn in  FIG. 16A . The alignment holes  1720 ,  1722  are directly opposite of one another.  
         [0159]      FIG. 17D  is a lateral view of an instrument  1730  used to align the ADR EPs drawn in  FIG. 17C .  FIG. 17E  is a coronal cross section of the ADR drawn in  FIG. 17C  and the alignment tool drawn in  FIG. 17D . The tool cooperates with the holes in the ADR EPs to align the ADR EPs.  
         [0160]      FIG. 18  is an anterior view of an alternative embodiment wherein the anterior surfaces of the ADR EPs have grooves or surface markings to align the ADR EPs. The tool drawn in  FIG. 17D  may fit into the grooves on the anterior surfaces of the ADR EPs.  
         [0161]      FIG. 19A  is an exploded lateral view of an ADR and alternative embodiment of the invention related to that drawn in  FIG. 9D . The device  1900  is attached to the upper and the lower ADR endplates (EPs  1902 ,  1904 ). Screws  1910  may be used to attach the device to the ADR EPs. Alternative methods may be used to fasten the device to the ADR EPs. For example, the fastening method could include the use of shape memory materials such as Nitinol.  
         [0162]      FIG. 19B  is a lateral view of the embodiment of the invention drawn in  FIG. 19A  and an ADR. The component  1900  prevents the ADR EPs from moving towards one another. For example, if the component was placed on the posterior portion of an ADR it would prevent spinal extension through the ADR. The screws and the component cooperate to prevent other motions such as lateral bending and axial rotation. The screws cooperate with the component to prevent the ADR EPs from separating. Thus, posterior placement of the device also prevents spinal flexion through the device. The device is preferably made of a biocompatible metal such as titanium or chrome cobalt. The device can also made of other biocompatible materials.  FIG. 19C  is a posterior view of the device and an ADR.  
         [0163]      FIG. 20  is the view of the top of an ADR and embodiments of the invention drawn in  FIG. 19A , showing how devices may be placed on the anterior  2002 , posterior  2004 , lateral  2006 , and/or posterior-lateral portions  2008  of an ADR.  
         [0164]      FIG. 21  is a posterior view of a an ADR having holes  2102 ,  2104  to receive the embodiment of the invention drawn in  FIG. 19A . The ADR also has novel projections  2110 ,  2112  from the ADR EPs. The projections are placed directly over the holes in the ADR EPs. Surgeons could use fluoroscopy to identify the projections from the ADR EPs. The location of the projections directs surgeons to the holes in the ADR EPs. Surgeons could use the alignment apparatus to minimize the length of the incision required to insert the device.  
         [0165]      FIG. 22  is a lateral view of an alternative embodiment of the invention and a sagittal cross section through a novel ADR  2204 . The device  2202  has elastic properties. The device is impacted over the ADR EPs to arrest movement through the ADR. Like the embodiment of the invention drawn in  FIG. 19A , the device fastens to the ADR EPs to prevent flexion, extension, lateral bending, translation, and/or axial rotation through the ADR.  
         [0166]      FIG. 23A  is an exploded lateral view of an alternative embodiment of the invention wherein threaded hook component  2302  passes through a blocker component  2304  and a hook component  2306 .  FIG. 23B  is a lateral view of the embodiment of the invention drawn in  FIG. 23A  and an ADR. The assembled device is tightened to clamp onto the upper and lower ADR EPs. The hook portions of the device may fit into recesses or holes in the ADR EPs. The device is tightened over the ADR by advancing the nut along the threaded portion of the superior hook component.  
         [0167]      FIG. 24A  is an exploded lateral view of an alternative embodiment of the invention drawn in  FIG. 23A .  FIG. 24B  is a lateral view of the embodiment of the invention drawn in  FIG. 24A  and a novel ADR. The device  2402  is fastened to the ADR EPs with screws  2410 . The stiffness of the device and the rigid attachment to the ADR EPs prevents movement through the ADR.  
         [0168]      FIG. 24C  is a view of the top of the embodiment of the ADR drawn in  FIG. 24B . The rectangular opening  2402  represents a space in the ADR EP that is filled with a bone growth promoting substance. BMP soaked collagen sponges could be used to promote fusion across the ADR. Rectangle  2404  with the dots represents the embodiment of the device drawn in  FIG. 24A . The two rectangles  2406 ,  2408  represent novel removable plugs in the ADR EPs. The plugs prevent bone from growing into the openings in the ADR EPs. The plugs are removed during revision surgery to place the embodiment of the device drawn in  FIG. 24A  and to insert bone growth promoting substances.  FIG. 24D  is a posterior view of the embodiment of the invention drawn in  FIG. 24C .  
         [0169]      FIG. 25A  is an exploded lateral view of an alternative embodiment of the invention, and  FIG. 25B  is a sagittal cross section of the embodiment of the invention drawn in  FIG. 25A  and an ADR. Screws  2502 ,  2504  are threaded through the blocker component  2510  represented by the dotted area of the drawing and into threaded holes in the ADR EPs. Alternatively, shape memory technology could be used to attach the device to the ADR EPs.  
         [0170]      FIG. 26A  is an exploded lateral view of an alternative embodiment of the invention, and  FIG. 26B  is a lateral view of the embodiment of the invention drawn in  FIG. 26A  and a sagittal cross section through an ADR. The hook portions  2602  of the device  2604  pass through holes or slots in the ADR EPs  2610 ,  2612 . The hook portions of the device attach the device to the ADR and hold a blocker component between the ADR EPs. The inferior hook component slides along the shaft extending from the superior hook component. A set-screw passes through the lower hook component and against the shaft of the upper hook component. The screw is tightened to clamp the device  2620  to the ADR.  
         [0171]      FIG. 27A  is an exploded lateral view of an alternative embodiment of the invention and an ADR.  FIG. 27B  is a lateral view of the embodiment of the invention drawn in  FIG. 27A . The rectangular shaped component  2702  fits into slots in the ADR EPs. The screws  2704  prevent the rectangular shaped component from backing out of the ADR.  
         [0172]      FIG. 27C  is a posterior view of the embodiment of the invention drawn in  FIG. 27B . The screws have not been inserted into the ADR EPs.  FIG. 27D  is a partial posterior view of an alternative embodiment of the invention related to that drawn in  FIG. 27C . The superior and inferior surfaces of the rectangular shaped component have projections  2730 ,  2732  that cooperate with the slots in the ADR EPs to help lock the component in the ADR EPs.  
         [0173]      FIG. 28A  is an exploded lateral view of an alternative embodiment of the invention, and  FIG. 28B  is an exploded view of the top of the embodiment of the invention drawn in  FIG. 28A .  FIG. 28C  is a lateral view of the embodiment of the invention drawn in  FIG. 28B  and an ADR. The wedge component  2802  is drawn in its first position.  FIG. 28D  is a lateral view of the embodiment of the invention drawn in  FIG. 28C . The wedge component has been rotated 90 degrees. The wedge component preferably fits into slots in the ADR EPs. The walls of the slots may be configured to facilitate rotation if the wedge component in one direction.  
         [0174]      FIG. 28E  is a view of the top of an ADR EP and the embodiment of the invention drawn in  FIG. 28B . A forked-shaped component  2810  is attached to the ADR EP. The arms of the forked shaped component straddle the sides of the wedge component to prevent counter rotation of the wedge component.  FIG. 28F  is a lateral view of the embodiment of the invention drawn in  FIG. 28E , wherein the forked shaped component has been fastened to the ADR EPs. The wedge component may course from anterior to posterior or obliquely across the ADR EPs in alternative embodiments of the invention.  
         [0175]      FIG. 29A  is a lateral view of an alternative embodiment of the invention wherein a wedge-blocker component  2902  expands after placement of the device between the ADR EPs. Expansion of the device in-situ eliminates the need to rotate the device in-situ.  FIG. 29B  is a lateral view of the embodiment of the invention drawn in  FIG. 29A . A threaded wedge component  2904  has been advanced to expand the tip of the blocker component. The device is placed between ADR EPs to prohibit movement across the ADR.  FIG. 29C  is a sagittal cross section of the embodiment of the invention drawn in  FIG. 29B .  
         [0176]      FIG. 30A  is a lateral view of the tip of an alternative embodiment of the invention, and  FIG. 30B  is a lateral view of the embodiment of the invention drawn in  FIG. 30A . The tip of the device  3002  expands as the screw  3004  is rotated.  FIG. 30C  is a lateral view of the embodiment of the invention drawn in  FIG. 30B  and an ADR. The device has been drawn in its contracted shape. The contracted shape facilitates insertion of the device.  
         [0177]      FIG. 31A  is a lateral view of an alternative embodiment of the device drawn in  FIG. 25A . A screw  3102  is advanced from a hole in one ADR EP. The screw impinges against the second ADR EP  3104  to prevent motion across the ADR.  FIG. 31B  is a view of the top of the inferior ADR EP drawn in  FIG. 31A . The ADR EP has two holes.  FIG. 31C  is a view of the top of the inferior ADR EP drawn in  FIG. 31B . Screws have been advanced partially through the holes in the ADR EPs. One or more screws may be advanced across the superior and or inferior ADR EPs. The screws may impinge against the second ADR EP. Alternatively, the screws may be threaded into holes in the second ADR EP.  
         [0178]      FIG. 32A  is a view of the articulating side of the ADR EP drawn in  FIG. 27A . The wedge component  3202  courses obliquely across the ADR.  FIG. 32B  is a view of the articulating side of an alternative embodiment of the invention drawn in  FIG. 32A . The wedge component  3204  courses from anterior to posterior. The wedge component may be limited to one half of the ADR. Alternatively, the wedge component may be limited to one quarter of the ADR. For example, the wedge component may be limited to the posterior half of the left side of the ADR.  
         [0179]      FIG. 32C  is a view of the articulating side of an alternative embodiment of the invention wherein multiple wedge components  3210 ,  3212  course across the ADR.  FIG. 32D  is a view of the articulating side of an alternative embodiment of the invention drawn in  FIG. 32C . The wedge component  3220  passes into the articulating surface of the ADR. A portion of the articulating surface may be removed to allow insertion of the wedge component. For example, a portion of a polyethylene component may be removed to insert a device according to the invention.  
         [0180]      FIG. 33  is a lateral view of an ADR and an alternative embodiment of the invention wherein an in-situ curing polymer  3302  is injected between the ADR EPs. For example, polymethylmethacrylate (PMMA) may be injected between the ADR EPs. Dye may be injected into the space between the ADR EPs prior to injecting the PMMA. Injection of a radio-opaque dye helps surgeons determine where the PMMA will flow. Alternatively, in-situ curing polyurethane or other polymer may be injected between the ADR EPs. The cured polymer is preferably stiff.  
         [0181]      FIG. 34A  is a lateral view of an alternative embodiment of the invention wherein a frame-like device  3402  is made of a shape memory material. For example the device could be made of Nitinol. The device expands in-situ as the temperature of the body heats the device.  FIG. 34B  is a lateral view of the embodiment of the invention drawn in  FIG. 34A . The device has expanded.  
         [0182]      FIG. 34C  is a lateral view of an ADR and the embodiment of the invention drawn in  FIG. 34B . The device is drawn in its expanded shape. The device expands after it is placed between the ADR EPs. The device may be used with other embodiments of the invention. For example, the in-situ curing PMMA drawn in  FIG. 33  could be injected into the ADR after inserted the shape memory frame.  
         [0183]      FIG. 35  is the view of the top of an alternative embodiment of the invention drawn in  FIG. 27A . The rectangular component has an elastic spring clip projection. The clip holds the component in the ADR EP. The clip eliminates the need for screws to hold the component in the ADR. Such spring-loaded mechanisms could alternatively be incorporated into the ADR EPs. Elastic locking mechanisms could be incorporated into other embodiments of the invention.  
         [0184]      FIG. 36A  is an oblique view of an alternative embodiment of the invention drawn in  FIG. 19A .  FIG. 36B  is a view of the posterior aspect of an alternative embodiment of the ADR drawn in  FIG. 5A  of my co-pending application U.S. patent application Ser. No. 10/741,290, the entire content of which is incorporated herein by reference.  
         [0185]      FIG. 36C  is a view of the posterior aspect of the embodiment of the ADR drawn in  FIG. 36B  and the posterior aspect of the embodiment of the invention drawn in  FIG. 36A . The arms of the device drawn in  FIG. 36A  fit into holes  3602  of the ADR. The elastic properties of the device cooperate with the holes in the ADR to lock the device in the ADR. The device prevents movement through the ADR.  
         [0186]      FIG. 36D  is a sagittal cross section through the embodiment of the ADR drawn in  FIG. 36B . The holes  3602  receive the arms of the device drawn in  FIG. 36A . The holes also allow bone to grow across the ADR. Bone growth material may be placed between the holes. For example, a BMP soaked collagen sponge could be placed between the holes in the ADR EPs. A drill may be passed diagonally from a hole in one ADR to a hole in the second ADR EP. The drill causes the vertebrae to bleed. The blood from the vertebrae and the bone growth material stimulate spinal fusion across the ADR. The device drawn in  FIG. 36A  immobilizes the ADR EPs. Immobilization of the ADR EPs facilitates fusion across the ADR EPs. The holes could be filled with Polyethylene. The polyethylene prevents bone from growing across the ADR EPs. The polyethylene may be removed with a drill during revision surgery. BMP soaked sponges may be packed into the freshly drilled holes in the ADR EPs and the holes drilled into the vertebrae.