Patent Publication Number: US-11647999-B1

Title: Method and apparatus for performing spine surgery

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/143,242, filed Apr. 29, 2016, now pending, which is a continuation of U.S. patent application Ser. No. 13/077,977 filed Mar. 31, 2011, now U.S. Pat. No. 9,351,845, which is a continuation-in-part of U.S. patent application Ser. No. 12/799,021 filed Apr. 16, 2010, now U.S. Pat. No. 8,287,597, which claims the benefit of U.S. Provisional Patent Application No. 61/212,921 filed Apr. 16, 2009 and U.S. Provisional Patent Application No. 61/319,823 filed Mar. 31, 2010, the entire contents of which are all hereby expressly incorporated by reference into this disclosure as if set forth in its entirety herein. The U.S. patent application Ser. No. 13/077,977 filed Mar. 31, 2011, now U.S. Pat. No. 9,351,845, also claims the benefit of priority from U.S. Provisional Patent Application No. 61/319,823 filed Mar. 31, 2010 and U.S. Provisional Patent Application No. 61/357,951 filed Jun. 23, 2010, the entire contents of which are each hereby expressly incorporated by reference into this disclosure as if set forth in its entirety herein. 
    
    
     FIELD 
     The present invention relates to implants, tools, and methods for adjusting sagittal imbalance of a spine. 
     BACKGROUND 
     A human spine has three main regions—the cervical, thoracic, and lumbar regions. In a normal spine, the cervical and lumbar regions have a lordotic (backward) curvature, while the thoracic region has a kyphotic (forward) curvature. Such a disposition of the curvatures gives a normal spine an S-shape. Sagittal imbalance is a condition in which the normal alignment of the spine is disrupted in the sagittal plane causing a deformation of the spinal curvature. One example of such a deformity is “flat-back” syndrome, wherein the lumbar region of the spine is generally linear rather than curved. A more extreme example has the lumbar region of the spine exhibiting a kyphotic curvature such that the spine has an overall C-shape, rather than an S-shape. Sagittal imbalance is disadvantageous from a biomechanical standpoint and generally results in discomfort, pain, and an awkward appearance in that the patient tends to be bent forward excessively. 
     Various treatments for sagittal imbalance are known in the art. These treatments generally involve removing at least some bone from a vertebra (osteotomy) and sometimes removal of the entire vertebra (vertebrectomy) in order to reduce the posterior height of the spine in the affected region and recreate the lordotic curve. Such procedures are traditionally performed via an open, posterior approach involving a large incision (often to expose multiple spinal levels at the same time) and require stripping of the muscle tissue away from the bone. These procedures can have the disadvantages of a large amount of blood loss, high risk, long operating times, and a long and painful recovery for the patient. 
     In some other treatments, achieving sagittal balance is accomplished by via an open, anterior approach to position an intervertebral implant between two affected vertebrae in order to increase the anterior height of the spine in the affected region and thereby recreate the lordotic curve. Effectuating an anterior spinal fusion typically involves retracting the great vessels (aorta and vena cava) and tissue adjacent to the anterior longitudinal ligament (ALL), then severing the ALL 16 to increase flexibility and permit insertion of the implant between the adjacent vertebrae. The anterior approach is advantageous in that the ALL 16 is generally exposed, allowing the physician to simply dissect across the exposed portion of the ALL 16 to access the spine. The anterior approach to the spine can also have the disadvantages of a large amount of blood loss, build-up of scar tissue near vital organs, and sexual dysfunction in males. Furthermore, depending upon the patient, multiple procedures, involving both anterior and posterior approaches to the spine, may be required. 
     In contrast, a lateral approach could be used to access a target spinal site, remove the intervertebral disc between two affected vertebrae, and insert an intervertebral implant. A lateral approach to the spine provides a number of advantages over the posterior and anterior approaches to the spine. Because a lateral approach may be performed without creating a large incision or stripping muscle from bone, this approach does not present the problems associated with a posterior approach, namely there is no large incision, muscle stripping, high blood loss, long operating time, or long and painful recovery for the patient. Furthermore, because a lateral approach to the spine does not involve exposing the anterior aspect of the ALL 16, retracting the great vessels and nearby tissues is unnecessary such that the risks of blood loss, scar tissue, and sexual dysfunction are much less likely to be encountered. 
     However, in patients with sagittal imbalance, release of the ALL 16 may be necessary to achieve the flexibility between the two affected vertebrae to facilitate insertion of an implant and achieve the amount of correction desired. A need exists for implants, tools, and methods for safe and reproducible means of releasing the ALL 16 via lateral approach as well as restoring the lordotic curvature of the lumbar spine. The present invention is directed at overcoming, or at least improving upon, the disadvantages of the prior art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many advantages of the present invention will be apparent to those skilled in the art with a reading of this specification in conjunction with the attached drawings, wherein like reference numerals are applied to like elements and wherein: 
         FIG.  1    is a lateral view representing a portion of a sagitally imbalanced lumbar spine lacking the normal lordotic curvature; 
         FIG.  2    is a lateral view representing the lumbar spine of  FIG.  1    after restoration of the lordotic curvature using a hyper-lordotic fusion implant, according to one example embodiment; 
         FIG.  3    is a top-down view depicting the creation of a lateral access corridor formed with a surgical access system via a lateral approach through the side of the patient to the target disc space, according to one example embodiment; 
         FIG.  4    is a perspective view depicting a lateral access corridor formed with a retractor assembly through the side of the patient to the target disc space, according to one example embodiment; 
         FIG.  5    is a front perspective view of an anterior longitudinal ligament (ALL) resector for safely releasing the ALL through a lateral access corridor, according to one example embodiment; 
         FIG.  6    is a side view of the ALL resector of  FIG.  5   ; 
         FIG.  7    is an enlarged side view of the distal end of the ALL resector of  FIG.  5   ; 
         FIG.  8    is a side view of an ALL resector for safely releasing the ALL through a lateral access corridor, according to another example embodiment; 
         FIG.  9    is an enlarged side view of the distal end of the ALL resector of  FIG.  8   ; 
         FIG.  10    is a front perspective view of an ALL resector for safely releasing the ALL through a lateral access corridor, according to another example embodiment; 
         FIG.  11    is an enlarged perspective view of the distal portion of the ALL resector of  FIG.  10   ; 
         FIG.  12    is an enlarged side view of the distal portion of the ALL resector of  FIG.  10   ; 
         FIG.  13    is an exploded front perspective view of the ALL resector of  FIG.  10   ; 
         FIG.  14    is a front view of an ALL resector for safely releasing the ALL through a lateral access corridor, according to another example embodiment; 
         FIG.  15    is a cross-section front view of the ALL resector of  FIG.  14   ; 
         FIG.  16    is a perspective view of a bending block for use with the ALL resector of  FIG.  14    according to one embodiment; 
         FIG.  17    is a perspective view of a bending block for use with the ALL resector of  FIG.  14    according to a second embodiment; 
         FIG.  18    is a bottom view of the bending block of  FIG.  17   ; 
         FIG.  19    is a front perspective view of a hand-held retraction tool for use with the ALL resector of  FIG.  14   ; 
         FIG.  20    is a front perspective view of the hand-held retraction tool of  FIG.  19    with an insulative sheath at the tip; 
         FIG.  21    is a perspective view of an ALL resector for safely releasing the ALL through a lateral access corridor according to another example embodiment; 
         FIG.  22    is an enlarged perspective view of the distal end of the ALL resector of  FIG.  21   ; 
         FIG.  23    is a perspective view of a retraction tool for use with the ALL resector of  FIG.  21   ; 
         FIG.  24    is a posterior side perspective view of a hyper-lordotic implant according to a first example embodiment; 
         FIG.  25    is an anterior side perspective view of the hyper-lordotic implant of  FIG.  24   ; 
         FIG.  26    is a lateral side view of the hyper-lordotic implant of  FIG.  24   ; 
         FIG.  27    is a posterior side perspective view of a hyper-lordotic implant according to a second example embodiment; 
         FIG.  28    is an anterior side perspective view of the hyper-lordotic implant of  FIG.  27   ; 
         FIG.  29    is a lateral side view of the hyper-lordotic implant of  FIG.  27   ; 
         FIG.  30    is a posterior side perspective view of a hyper-lordotic implant according to a third example embodiment; 
         FIG.  31    is an anterior side perspective view of the hyper-lordotic implant of  FIG.  30   ; 
         FIG.  32    is a lateral view of the hyper-lordotic implant of  FIG.  30   ; 
         FIG.  33    is a posterior side perspective view of a hyper-lordotic implant according to a fourth example embodiment; 
         FIG.  34    is a posterior side perspective view of a hyper-lordotic implant according to a fifth example embodiment; 
         FIG.  35    is another perspective view of the hyper-lordotic implant of  FIG.  34   ; 
         FIGS.  36  and  37    are perspective views of an example anchor for securing the position of the hyper-lordotic implant of  FIG.  34   ; 
         FIGS.  38  and  39    are perspective views of an example locking element for securing the anchor of  FIGS.  36  and  37    to the implant of  FIG.  34   ; 
         FIGS.  40 - 41    illustrate the locking element of  FIG.  38    being engaged to the anchor of  FIGS.  36  and  37   ; 
         FIG.  42    is a posterior side perspective view of a hyper-lordotic implant according to a sixth example embodiment; 
         FIG.  43    is an anterior side perspective view of the hyper-lordotic implant of  FIG.  42   ; 
         FIG.  44    is a lateral side view of the hyper-lordotic implant of  FIG.  42   ; 
         FIG.  45    is a perspective view of an example fixation anchor for securing the position of the hyper-lordotic implant of  FIG.  42   ; 
         FIG.  46    is an anterior side view of the hyper-lordotic implant of  FIG.  42    with the fixation anchors of  FIG.  45    positioned; 
         FIG.  47    is posterior side view of the implant and anchors of  FIG.  46   ; 
         FIG.  48    is a lateral side view of the implant and anchors of  FIG.  46   ; 
         FIG.  49    is a perspective view of an insertion instrument for implanting the hyper-lordotic implants, according to one example embodiment; 
         FIG.  50    is an enlarged perspective view of the distal head of the insertion instrument of  FIG.  49   ; 
         FIG.  51    is a perspective view of the insertion instrument of  FIG.  49    coupled to the hyper-lordotic implant of  FIG.  24   ; 
         FIG.  52    is a perspective view of a guided clip attachment that can be attached to the insertion instrument of  FIG.  49    for guiding the insertion of the implant along a path defined by the tissue retractor assembly of  FIG.  3   , according to one example embodiment; 
         FIG.  53    is an exploded view of the guided clip attachment of  FIG.  52   ; 
         FIG.  54    is an enlarged view of an attachment base of the guided clip attachment of  FIG.  52   ; 
         FIG.  55    is a perspective view of the guided clip attachment of  FIG.  52    coupled to the insertion instrument of  FIG.  49    which is coupled to the implant of  FIG.  24   ; 
         FIG.  56    is side view of the guided clip attachment of  FIG.  52    engaged with a retractor blade of the tissue retractor assembly of  FIG.  3   ; 
         FIG.  57    is an enlarged view of the guided clip attachment of  FIG.  52    engaged with a retractor blade of the tissue retractor assembly of  FIG.  3   ; 
         FIG.  58    is a side view of the guided clip attachment, inserter, and implant of  FIG.  55    engaged with a retractor blade of the tissue retractor assembly of  FIG.  3   ; 
         FIG.  59    is a perspective view of an inserter instrument with an integrated attachment clip, according to an embodiment of the present invention; 
         FIG.  60    is a side angle enlarged view of the inserter of  FIG.  59    engaged with a retractor blade of the tissue retractor assembly of  FIG.  3   ; 
         FIG.  61    is a side angle view of the inserter of  FIG.  59    engaged with a retractor blade of the tissue retractor assembly of  FIG.  3   ; and 
         FIG.  62    is a flow chart indicating the steps utilized to restore lordosis to the spine of a patient, according to one example method. 
     
    
    
     DETAILED DESCRIPTION 
     Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. The methods and devices described herein include a variety of inventive features and components that warrant patent protection, both individually and in combination. 
     With reference to  FIGS.  1 - 2   , devices and methods described herein are utilized to correct sagittal imbalance, including lumbar kyphosis, by increasing the anterior height of the affected spinal area (as opposed to reducing the posterior height, for example via a pedicle subtraction osteotomy).  FIG.  1    illustrates a portion of the lumbar spine lacking the standard lordotic curvature. To correct the sagittal imbalance, illustrated in  FIG.  2   , a hyper-lordotic implant  10  is positioned into the disc space at the appropriate spinal level (e.g. between V1 and V2). An anterior sidewall  12  of hyper-lordotic implant  10  has a height significantly larger than an opposing posterior sidewall  14  such that when the implant is positioned within the disc space the anterior aspects of V1 and V2 are forced apart while the posterior aspects are not (or at least not to the same degree), thus imparting a lordotic curvature into the spine. To allow the anterior aspects of V1 and V2 to separate and receive the hyper-lordotic implant  10 , the anterior longitudinal ligament (ALL)  16  that runs along the anterior aspect of the spine may be released or cut  18 . Releasing the ALL provides greater flexibility of movement between the adjacent vertebral bodies, which allows for a larger height implant and provides greater opportunity to establish or re-establish a generally normal lordotic curvature in the lumbar region of the spine. 
     According to a preferred method, the implant  10  is implanted through a lateral access corridor formed through the side of the patient. Accessing the targeted spinal site through the lateral access corridor avoids a number of disadvantages associated with posterior access (e.g. cutting through back musculature and possible need to reduce or cut away part of the posterior bony structures like lamina, facets, and spinous process) and anterior access (e.g. use of an access surgeon to move various organs and blood vessels out of the way in order to reach the target site). Accordingly, by accessing the target site via a lateral access approach and correcting the sagittal imbalance without reducing the posterior height (i.e. no bone removal) the high blood loss and painful recovery associated previous methods may be avoided (or at least mitigated). 
     According to one example, the lateral access approach to the targeted spinal space may be performed according to the instruments and methods described in commonly owned U.S. Pat. No. 7,207,949 entitled “Surgical Access System and Related Methods,” and/or U.S. Pat. No. 7,905,840 entitled “Surgical Access System and Related Methods,” the entire contents of which are each incorporated herein by reference as if set forth herein in their entireties. With reference to  FIGS.  3 - 4   , a discussion of the lateral access instruments and methods is provided in brief detail. With the patient  20  positioned on his side, a surgical access system  22  is advanced through an incision  24 , into the retroperitoneal space  26 , and then through the psoas muscle  28  until the targeted spinal site (e.g. the disc space between V1 and V2) is reached. The access system  22  may include at least one tissue dilator, and preferably includes a sequential dilation system  30  with an initial dilator  32  and one or more additional dilators  34  of increasing diameter, and a tissue retractor assembly  36 . As will be appreciated, the initial dilator  32  is preferably advanced to the target site first, and then each of the additional dilators  34  of increasing diameter are advanced in turn over the previous dilator. A k-wire (not shown) may be advanced to the target site and docked in place (for example, by inserting the k-wire into the vertebral disc) prior to, in concurrence with, or after advancing the initial dilator  32  to the target site. 
     With the sequential dilation system  30  positioned adjacent the target site (and optionally docked in place via a k-wire), the retractor assembly  36  is advanced to the target site over the sequential dilation system  30 . According to the embodiment shown, the retractor assembly  36  includes retractor blades  38 ,  40 ,  42  and a body  44 . With the sequential dilation system  30  removed, the retractor blades  38 ,  40 , and  42  are separated ( FIG.  4   ), providing the lateral access corridor through which instruments may be advanced to prepare the disc space and insert the implant  10 . According to one example, the posterior blade  38  may be fixed in position relative to the spine prior to opening the retractor blades. This may be accomplished, for example by attaching a shim  45  to the blade  38  (e.g. via track  46  including dove tail grooves  48  formed on the interior of blade  38 ) and inserting the distal end of the shim  45  into the disc space. In this manner, the posterior blade  38  will not move posteriorly (towards nerve tissue located in the posterior portion of the psoas muscle  28 ). Instead, the blades  40  and  42  will move away from the posterior blade  38  to expand the access corridor. Additionally, nerve monitoring (including determining nerve proximity and optionally directionality) is performed as at least one component of the access system, and preferably each component of the access system  22  is advanced through the psoas muscle  28 , protecting the delicate nerve tissue running through the psoas, as described in the &#39;949 and &#39;840 patents. Monitoring the proximity of nerves also allows the posterior blade  38  of the retractor assembly  36  to be positioned very posterior (all the way back to the exiting nerve roots), thus exposing a greater portion of the disc space than would otherwise be safely achievable. This in turn permits full removal of the disc and implantation of an implant with a wider footprint implant. Use of a wider footprint meanwhile makes utilization of a hyper-lordotic implant with a large lordotic angle (e.g. between 20-40 degrees) more practical. 
     With the lateral access corridor formed (as pictured in  FIG.  4   ) the target site may be prepped for insertion of the implant  10 . Preparation of the disc space may include performing an annulotomy, removal of disc material, and abrasion of the endplates. Instruments such as annulotomy knives, pituitaries, curettes, disc cutters, endplate scrapers may be used during disc preparation. Additionally, as discussed above, it may be necessary to release the ALL 16 in order to create enough flexibility between the adjacent vertebrae (e.g. V1 and V2) to receive the hyper-lordotic implant  10 . Unlike an anterior approach (where the great vessels and other tissue lying anterior to the disc space are retracted during the approach), when the target disc is approached laterally, the great vessels remain adjacent to the ALL along the anterior face of the spine. Thus, while cutting the ALL is generally simple and necessary during an anterior approach surgery, cutting the ALL during a lateral approach surgery has typically been unnecessary and can be difficult because of the need to avoid damaging the great vessels. Accordingly,  FIGS.  5 - 23    set forth various example embodiments of ALL resecting instruments for safely releasing the ALL from a lateral approach. 
       FIGS.  5 - 7    illustrate an example embodiment of an ALL resector  50 . By way of example only, the ALL resector  50  can be used to release (by way of cutting) the ALL anterior to the operative disc space in surgeries requiring a large degree of curvature correction (for example, greater than 15 degrees). The ALL resector  50  includes a handle  52  (for example, a T-handle) located at the proximal end of the elongated shaft  54  and a distal head  56  for resecting the ALL 16. The distal head  56  includes distally extending first and second fingers  58 ,  60 , which form an opening  62  therebetween. First and second tapered surfaces  64 ,  66  which extend a distance from the elongated shaft  54  along the fingers  58 ,  60  enable the distal head  56  to insert gently between tissue. As best shown in  FIG.  7   , the first finger  58  may be shorter in length than the second finger  60 . This may serve a variety of purposes, which include giving the user greater viewing capabilities of the cutting area due to a shorter first finger  58  while providing greater protection and insertion guidance with a longer second finger  60 . However, the first and second finger  58 ,  60  may be provided in any number of length configurations without departing from the scope of the present invention. By way of example, it has been contemplated that the first finger  58  may be completely removed. Alternatively the fingers may be curved (as illustrated in the embodiment depicted in  FIGS.  8 - 9   ) and have a more substantial width than shown in  FIGS.  5 - 7   . Curvature of the first and second fingers may allow the distal head  56  to follow closely along the anterior side of the spine and/or along a curved spatula (not shown) positioned adjacent the anterior side of the vertebral body. Though not shown, a user may optionally insert a spatula along the anterior portion of the ALL 16 prior to inserting the ALL retractor  50 . The spatula may serve as additional protection between the delicate tissue anterior to the ALL and the cutting blade  68  of the ALL resector  50 . With a spatula in place the user may insert the distal head  56  such that it approaches the lateral side of the ALL 16 and is guided along the inside edge of the spatula. By way of example, the spatula may be straight or curved to match the selected fingers of the distal head  56 . 
     A cutting blade  68  is exposed between the first and second fingers  58 ,  60  in the opening  62 . A slot  70  formed along a side of the distal head  56  allows a cutting blade  68  to be inserted and removed from the distal head  56  as needed (such as, for example, if a blade were to become dull or bent). Thus, the cutting blade  68  may be disposable and the remainder of the ALL resector  50  may be reusable. Alternatively, both cutting blade  68  and remainder of the ALL resector  50  may be reusable or both may be disposable. In use, the ALL resector  50  is preferably positioned such that the second finger  60  is aligned along the anterior side of the ALL and the first finger  58  is aligned along the posterior side of the ALL 16, thus, at least partially bounding the ALL 16 on either side which allows the cutting blade  68  to maintain a generally perpendicular alignment relative to the length of the ALL 16. The ALL resector  50  is advanced forward so that the cutting blade  70  cuts through the ALL 16 from one lateral edge to the other. As discussed above, the second finger  60  is preferably aligned along the anterior side of the ALL 16 as the distal head  56  is advanced, thereby shielding the tissue lying anterior to the finger  60  (e.g. great vessels, etc. . . . ) from the cutting blade  68 . Furthermore, as the user advances the ALL resector  50 , the fingers  58 ,  60  may also act as a stabilizing guide. 
       FIGS.  8 - 9    illustrate an ALL resector  72  according to a second example embodiment. The ALL resector  72  differs from the ALL resector  50  in that its first and second fingers  74 ,  76  are generally curved. The remainder of the features and functions of the ALL resector  72  are essentially the same as the features and functions of the ALL resector  50  such that they will not be repeated here. The curvature of the first and second fingers  74 ,  76  allow the distal head  56  to follow closely along the anterior aspect of the spine. By way of example, the curvature of the second finger  76  allows the distal head  56  to more easily slide along a curved spatula (not shown) positioned adjacent to the anterior aspect of the vertebral body. Both the curved spatula and first and second fingers  74 ,  76  are curved to generally mimic the curvature of the anterior aspect of the spine. This enables a surgeon to more easily maneuver the distal head  56  while cutting across the ALL 16. 
     Additionally, it has been contemplated that the first and second fingers  74 ,  76  be sized and shaped to have a greater width than the first and second fingers  58 ,  60  of ALL resector  50 . Added width of the fingers may provide for increased protection and shielding of the cutting area while adding greater stability during insertion. 
       FIGS.  10 - 13    illustrate an ALL resector  78  according to a third example embodiment. The ALL resector  78  includes a tissue retractor  80  and a sliding blade  82  which function to both cut the ALL 16 and protect surrounding tissue, blood vessels, and nerves from unwanted damage (similar to the previous embodiments discussed above with reference to ALL resectors  50  and  72 ). The tissue retractor  80  includes a handle  84 , hollow shaft  86 , and head  88 . The head  88  is curved, preferably such that the inside surface  90  complements the curvature of the anterior aspects of the spinal target site. The head  88  may thus be positioned through the lateral access corridor to the spine and such that the curved interior surface  90  nestles around the curved anterior aspect of the spine. The outside surface  92  will form a barrier, protecting tissue along the anterior spine from inadvertent contact with the sliding blade when the ALL 16 is cut. Furthermore, the tissue retractor  80  can be further manipulated to move tissue and further expose the anterior aspect of the target site. The hollow shaft  86  includes a central lumen  94  with an opening adjacent the head  88  and another opening at the opposing end such that the sliding blade  82  may travel through the shaft  86 . 
     The sliding blade  82  includes a blade  96  that is secured to the distal end of an extender  98  by way of an attachment feature  100 . The attachment feature  100  as shown is similar to known attachment features used for attaching a blade at the end of a scalpel. It will be appreciated that any number of mechanisms may be used to attach blade  96  to extender  98 . Blade  96  may be disposable and extender  98  may be reusable. Alternatively, both blade  96  and extender  100  may be reusable or both may be disposable. The blade  96  includes a cutting edge  102  that, when advanced beyond the lumen  94  of shaft  86 , cuts through tissue or material situated adjacent the cutting edge  102 . 
     The proximal end of the extender  98  includes a grip  104  that a surgeon or other user may use to manipulate the position of the sliding blade  82  relative to the shaft  86  and head  88 . At least one stop feature  106  extends from the outer surface of the extender  98  which engages with a track  108  that extends along a portion of the elongated shaft  86 . The track  108  limits the longitudinal travel of the sliding blade  82  relative to the shaft  86  so that the sliding blade  82  remains slidably mated to the tissue retractor  80  without becoming unassembled and such that the blade  96  cannot extend beyond the protective head  88 . Additionally, the stop feature  106  restricts rotation of the sliding blade  82  relative to the tissue retractor  80 . 
       FIGS.  14 - 20    illustrate an ALL resector  110  according to a fourth example embodiment. As shown in  FIGS.  14 - 15   , the ALL resector  110  is comprised of a handle  112 , a conductive shaft  114 , a bendable region  116 , an anode tip  118 , and an electrical connector (not shown). Preferably, the conductive shaft  114  is coated with an insulative coating  118  about its exterior surface. In some embodiments, the bendable region  116  may be generally hook-shaped  120  such that the anode tip  118  would be oriented in an optimal angle for resecting the ALL 16 from the lateral approach. Alternatively, the bendable region  116  may be generally straight in shape such that customizable bending may be achieved as will be described below. 
       FIG.  16    illustrates a bending block system  122  according to one example embodiment for bending the bendable region  116  of the ALL resector  110 . Bending block  122  may be generally square or rectangle-shaped and is comprised of a handle  126  and one or more bending slot  128 . The bending slots  128  may be of different lengths such that the bendable region  116  of the ALL resector  110  may be placed in a bending slot  128  and then bent to an appropriate angle for cutting based in part upon considerations of surgeon preference as well as patient anatomy.  FIGS.  17 - 18    illustrate a bending block system  124  according to a second example embodiment. Bending block  124  may be generally circular in shape and comprised of a handle  126  and one or more bending slots  128 . Similar to the previous embodiment, the bending slots  128  may be of different lengths such that the bendable region  116  of the ALL resector  110  may be placed in a bending slot  128  and then bent to an appropriate angle for cutting based in part upon surgeon preference as well as patient anatomy restrictions. 
     The ALL resector  110  is preferably compatible with a hand-held retraction tool, for example the hand-held retraction tool  130  of  FIG.  19   . The retraction tool  130  is comprised of a handle  132 , a shaft  134 , and a paddle  136 . The paddle  136  may be bent or straight such that it is able to separate and form a barrier between the great vessels and the ALL resector  110 . Preferably, the retraction tool  130  is non-conductive. This may be accomplished by constructing the retraction tool  130  of non-conductive material or by coating the surfaces of the retraction tool with an insulating material. According to one example, the paddle  136  is rigid enough to achieve retract the great vessels without yielding under the weight of the vessels. According to another example, the paddle  136  may be flexible such that it can be inserted under the great vessels and flex up as the ALL resector  110  is advanced underneath the paddle  136  to cut the ALL. As shown in  FIG.  20   , a protective sheath  138  may surround the paddle  136  of the retraction tool  130  for added protection when the paddle  136  contacts the great vessels. 
     To use the ALL resector  110 , the surgeon may preferably first insert the retraction tool  130  between the ALL 16 and the great vessels, aligning the paddle  136  in a manner that protects the vessels without over-retracting them. The surgeon determines the ideal angle to approach the ALL 16 and whether to use a hooked, straight, or custom-bent tip. Once the ALL resector  110  is prepared with the preferred tip  118 , the electrical connector can be connected to an electrosurgical unit that delivers electrical current to the anode tip  118  in an amount that will cauterize (thus cut) the tissue of the ALL. The non-conductive paddle  136  of the retraction tool  130  protects the great vessels from the cauterizing effect of the electrical current. 
       FIGS.  21 - 23    illustrate yet ALL resector  142  according to a fifth example embodiment. The ALL resector  142  includes a tissue retractor component  144  and a cutter component  146  which work in concert to cut the ALL and protect surrounding tissue, blood vessels, and nerves from unwanted damage (similar to the other ALL resector embodiments discussed above). The tissue retractor  144  protects against anterior migration of the cutter  146  towards the great vessels and includes a handle  148 , an elongate shaft  150 , and a head  152 . The head  152  is curved, preferably in such a way that the inside surface  154  compliments the curvature of the anterior aspects of the spinal target site. The head  152  may thus be positioned through the lateral access corridor to the spine such that the curved interior surface  154  nestles around the curved anterior aspect of the spine. The outside surface  156  will form a barrier, protecting tissue along the anterior spine from inadvertent contact with the cutting edge  166  of the cutter  146  when the ALL 16 is cut. Furthermore, the tissue retractor  144  can be further manipulated to move tissue and further expose the anterior aspect of the target site. The elongate shaft  150  includes two guide posts  158  that are sized and dimensioned to function as a track to allow the cutter  146  to travel between the guide posts  158  and along the length of the elongate shaft  150  as will be described below. 
     The cutter  146  includes a blade  160  that is secured to the distal end of an extender  162  by way of an attachment feature  164 . The attachment feature  164  as shown is similar to known attachment features used for attaching a cutting blade at the end of a scalpel. In the embodiment shown, the blade  160  includes only a single cutting edge  166 , however it is contemplated that more than one cutting edge  166  may be utilized. It will be appreciated that any number of mechanisms may be used to attach blade  160  to extender  162 . Blade  160  may be disposable and extender  162  may be reusable. Alternatively, both blade  160  and extender  162  may be reusable or both may be disposable. The blade  160  includes a cutting edge  166  that, when advanced along the elongate shaft  150  of the retractor component  144 , cuts through tissue or material situated adjacent the cutting edge  166 . 
     The proximal end of the extender  162  includes a connector  168  to which a handle may be connected that a surgeon may use to manipulate the position of the cutter  146  relative to the shaft  150  and head  152 . At least one anti-rotation bar  170  extends from the outer surface of the extender  162  which can be slidably inserted between guide posts  158  and travel along a portion of the elongated shaft  150 . When the cutter  146  is positioned with the anti-rotation bar  170  between the guide posts  158 , the guide posts  158  keeps the cutter  146  slidably mated to the tissue retractor  144  and restricts rotation of the cutter  146  relative to the tissue retractor  144 . Further, the cutter  146  is restricted from movement in the cephalad/caudal direction by the vertebral bodies V1 and V2. Additionally, the extender  162  includes a pair of distal wings  172  protruding generally perpendicularly from the outer surface of the extender  162 . Distal wings  172  are sized and dimensioned to contact the proximal surfaces of V1 and V2 when the blade  160  is fully advanced across the ALL in order to act as a depth stop and restrict excessive advancement of the cutting blade  160 . The cutting blade  160  may also be provided with an elongated finger  174  as shown in  FIG.  22   , that may be used for further protection of nearby tissue (for example, the posterior longitudinal ligament or the great vessels) and as stabilizer during use. 
     While the ALL resectors  50 ,  72 ,  78 ,  110 ,  142  are susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the scope and spirit of the invention as defined herein. Furthermore, the ALL resectors  50 ,  72 ,  78 ,  110 ,  142  may be incorporated into a surgical kit or used with any number of various tooling and/or implants. The following are examples of tooling and implants that may be used in conjunction with the ALL resectors discussed herein, as well as any variation of an ALL resector not disclosed herein. 
     As discussed above, a patient may undergo a lateral procedure and have an intervertebral disc space prepared for the permanent implantation of, for example, a hyperlordotic implant. The intervertebral space may be prepared via any number of well-known surgical preparation tools, including but not limited to, kerrisons, rongeurs, pituitaries, and rasps. Preparation of the disc space may also include the removal of any implants already occupying the disc space. By way of example only, during a revision surgery, it may be necessary to remove a spinal fusion implant or TDR device previously implanted. 
     Once the disc space is prepared, the surgeon may designate the appropriate implant size. This may be accomplished through the use of a trial sizer (not shown). The trial sizer may include grooves along at least a portion of the upper and/or lower surfaces to help insert the sizer along the desired path through the intervertebral space. The sizer may also be connected to a guide clip attachment that can be guided along the retractor blade  38  of the retractor assembly (as will be described below in connection with the implant insertion). When the appropriate size is determined, an insertion instrument, for example, insertion instrument  310  may then be secured to an implant such that the implant is advanceable into the prepared intervertebral disc space. 
     Turning now to  FIGS.  24 - 48   , various embodiments of a hyper-lordotic implant for insertion through a lateral approach are described.  FIGS.  24 - 26   , for example, illustrate an implant  200  according to a first embodiment. Implant  200  may preferably be comprised of any suitable non-bone composition having suitable radiolucent characteristics, including but not limited to polymer compositions (e.g. poly-ether-ether-ketone (PEEK) and/or poly-ether-ketone-ketone (PEKK)) or any combination of PEEK and PEKK. Other materials such as for example, metal, ceramics, and bone may also be utilized for the implant  200 . Implant  200  has a top surface  202  and bottom surface  204  for contacting V1 and V2, anterior sidewall  206 , posterior sidewall  208 , and front or leading side  210 , and rear or trailing side  212 . As discussed, the anterior sidewall  206  has a height greater than the posterior sidewall  208  such that the top surface  202  and bottom surface  204  converge towards each other in the posterior direction. As shown in  FIG.  27   , the angle of convergence is represented by a. By way of example, the top and bottom surfaces may converge at an angle between 20 and 40 degrees. It is contemplated that variations of the implant  200  may be simultaneously provided such that the user may select from different available ranges. For example, variations may be provided with 20 degree, 30 degree, and 40 degree angles. The top and bottom surfaces may be planar or provided as convex to better match the natural contours of the vertebral end plates. The top surface  202  and the bottom surface  204  may be interchangeable (i.e. the implant may be flipped) such that the same implant may be implanted from either the left or right side of the patient. 
     The implant  200  may be provided with any number of additional features for promoting fusion, such as fusion apertures  214  extending between the top and bottom surfaces  202 ,  204  which allow a boney bridge to form through the implant  200 . Various osteoinductive materials may be deposited within the apertures  214  and/or adjacent to the implant  200  to further facilitate fusion. Such osteoinductive materials may be introduced before, during, or after the insertion of the exemplary spinal fusion implant  200 , and may include (but are not necessarily limited to) autologous bone harvested from the patient receiving the spinal fusion implant, bone allograft, bone xenograft, any number of non-bone implants (e.g. ceramic, metallic, polymer), bone morphogenic protein, and bio-resorbable compositions, including but not limited to any of a variety of poly (D,L-lactide-co-glycolide) based polymers. Visualization apertures  216  situated along the sidewalls, may aid in visualization at the time of implantation and at subsequent clinical evaluations. More specifically, based on the generally radiolucent nature of the preferred embodiment of implant  200 , the visualization apertures  216  provide the ability to visualize the interior of the implant  200  during X-ray and/or other imaging techniques. Further, the visualization apertures  216  will provide an avenue for cellular migration to the exterior of the implant  200 . Thus the implant  200  will serve as additional scaffolding for bone fusion on the exterior of the implant  200 . 
     The spinal fusion implant  200  may be provided in any number of sizes by varying one or more of the implant height, width, and length. The length of the implant  200  is such that it may span from one lateral aspect of the disc space to the other, engaging the apophyseal ring on each side. By way of example, the implant  200  may be provided with a length between 40 mm and 60 mm. The size ranges described are generally appropriate for implantation into the lordotic lumbar portion of the spine. The dimensions of the implant  200  may be altered according to proportions of the particular patient. Further, variation of the implant dimensions may be implemented to produce implants generally appropriate for implantation into any portion of the spine. By way of example only, the posterior sidewall  208  may be dimensioned at a height greater than that of anterior sidewall  206  such that top surface  202  and bottom surface  204  converge toward one another at the anterior sidewall  206  (e.g. to create a hyper-kyphotic implant) in order to promote the proper kyphotic angle in the thoracic spine. 
     As shown in  FIGS.  24 - 25   , the implant  200  may include anti-migration features designed to increase the friction between the spinal fusion implant  200  and the adjacent contact surfaces of the vertebral bodies, and thereby minimize movement or slippage of the implant  200  after implantation. Such anti-migration features may include ridges  220  provided along the top surface  202  and/or bottom surface  204 . Additional anti-migration features may also include spike elements  222  disposed along the top  202  and bottom surfaces  204 . The spike elements  222  may be manufactured from any of a variety of suitable materials, including but not limited to, a metal, ceramic, and/or polymer material, preferably having radiopaque characteristics. The spike elements  222  may each comprise a unitary element extending through the top surface  202  and bottom surface  204 . Alternatively, each spike element  222  may comprise a shorter element which only extends to a single surface. In any event, when the spike elements  222  are provided having radiodense characteristics, and the implant  200  is manufactured from a radiolucent material (such as, by way of example only, PEEK or PEKK), the spike elements  222  will be readily observable under X-ray or fluoroscopy such that a surgeon may track the progress of the implant  200  during implantation and/or the placement of the implant  200  after implantation. 
     Tapered surfaces  224  may be provide along the leading end  210  to help facilitate insertion of the implant  200 . Additional instrumentation may also be used to help deploy the implant  200  into the disc space. By way of example, the implant installation device shown and described in detail in the commonly owned and copending U.S. patent application Ser. No. 12/378,685, entitled “Implant Installation Assembly and Related Methods,” filed on Feb. 17, 2009, the entire contents of which is incorporated by reference herein, may be used to help distract the disc space and deposit the implant therein. 
     The spinal fusion implant  200  may be provided with any number of suitable features for engaging the insertion instrument  310  (illustrated in  FIG.  49   ). As best viewed in  FIG.  24   , one such engagement mechanism involves a threaded receiving aperture  226  in the posterior sidewall  208  of the implant  200 . The threaded receiving aperture  226  is dimensioned to threadably receive a threaded connector  182  on the insertion instrument  310 . In addition to the receiving aperture  226 , the implant  200  is preferably equipped with a pair of grooved purchase regions  228  extending either generally vertically or generally horizontally from either side of the receiving aperture  226 . The grooved purchase regions  228  are dimensioned to receive corresponding distal head plates  326  on the insertion instrument  310 . Together, these engagement mechanisms provide an enhanced engagement between the implant  200  and insertion instrument  310  and prevent unwanted rotation of the implant  200  during insertion as will be described in greater detail below. Having been deposited in the disc space, the implant  200  facilitates spinal fusion over time by maintaining the restored curvature as natural bone growth occurs through and/or past the implant  200 , resulting in the formation of a boney bridge extending between the adjacent vertebral bodies V1 and V2. 
       FIGS.  27 - 29    illustrate an implant  230  according to a second example embodiment of a hyper-lordotic implant. The implant  230  shares many similar features with the implant  200  such that repeat discussion in not necessary. The implant  230  differs from the implant  200  in that a trailing side  212  is configured for fixed engagement to one of the adjacent vertebral bodies (i.e. V1 or V2) to supplement the anti-migration features and ensure the hyper-lordotic implant is not projected out of the disc space. Specifically, the implant  230  includes a tab  232  extending vertically above the top surface  202  and below the bottom surface  204 . 
     In the example shown, the tab  232  is arcuate at the corners and generally trapezoidal, however, it should be appreciated that the tab  232  may take any number of suitable shapes, such as, by way of example only, square, rectangular, triangular, partially circular, or partially ovular, among others, the tab may be of different lengths. It should also be appreciated that tab  232  surfaces may be one or more of generally concave, generally convex, or generally planar. The tab  232  is comprised of a perimeter surface  234 , an anterior side  236 , a posterior side  238 , and a tab side  240 . Anterior side  236  and posterior side  238  may be interchangeable (i.e. the implant may be flipped horizontally or vertically) such that the same implant may be implanted from either the right side or the left side of the patient. Anterior side  236  and posterior side  238  are preferably, though not necessarily, configured coplanar with anterior sidewall  206  and posterior sidewall  208 , respectively (i.e. the width of tab  232  is preferably equal to the width of the implant proximal end, however, the width of the tab may be greater than, or less than, the width of the implant at proximal end). Tab side  240  of tab  232  is configured to engage the exterior surface of an adjacent vertebrae. 
     The tab  232  is provided with a fixation aperture  242  for enabling the engagement of a fixation anchor  302  within the vertebral bone to secure the placement of the implant  230 . The fixation aperture  242  may have any number of shapes and/or features for enabling an anchor (for example the fixation anchor  302  of  FIG.  45   ) to engage and secure the positioning of an implant  230 . The anchor engages within the vertebral bone through the fixation aperture  242  to secure the placement of the implant  230 . In use, when the implant  230  is positioned within the disc space, the tab  232  engages the exterior of the upper and lower vertebra and the anchor  302  may be driven into the side of either the upper or lower vertebra, depending on the orientation of the implant  230 . One will appreciate that various locking mechanisms may be utilized and positioned over or within the fixation aperture  234  to prevent the anchor  302  from unwanted disengagement with the implant  230 . For example, a suitable locking mechanism may be in the form of a canted coil disposed within the fixation aperture  234  (as illustrated in  FIG.  42   ), or may be engaged to the trailing end  212  and cover all or a portion of the fixation aperture  242  after the anchor  302  is positioned. 
       FIGS.  30 - 32    illustrate an implant  248  according to a third example embodiment of a hyper-lordotic implant. The implant  248  shares many similar features with the implants  200  and  230  such that repeat discussion of them all is not necessary. The implant  248  differs from the implant  230  in that the tab  249  extends higher (or lower depending on the insertion orientation) from the surface of the implant and solely in one direction such that it only engages the exterior of the upper (or lower) vertebra and the tab  249  has a partially ovular shape where it extends from the implant. Any number of features to prevent the backing out of an anchor may be utilized with this embodiment. 
       FIG.  33    illustrates a implant  250  according to a fourth example embodiment a hyper-lordotic implant. The implant  248  shares many similar features with the implants  200 ,  230 , and  248  such that repeat discussion of them all is not necessary. The implant  250  differs from the previous embodiments in that it is configured for fixation to one of the adjacent vertebrae but does not utilize a tab or tabs to do so. Instead, the implant  250  has one or more fixation apertures  252  that travel through the body of the implant  250 . The fixation apertures  252  are formed at an angle from a side of the implant such that the anchors will travel through the fixation apertures  252  into the vertebral bodies through the vertebral endplate. Any number of features to prevent the backing out of an anchor may be utilized with this embodiment. 
       FIGS.  34 - 41    illustrate an implant  260  according to a fifth example embodiment of a hyper-lordotic implant. The features and functions are essentially the same as the features and functions described with reference to the implants  230 ,  248 , and  250  such that they will not be repeated here. However, spinal fusion implant differs from the implants described above in that fixation apertures  261  are configured for engagement with anchors  262  that are anchored into the vertebral bodies before the implant  260  is implanted.  FIGS.  36 - 37    illustrate an example of an anchor  262  specially for use with the implant  260 . The anchor  260  is designed to be implanted prior to the implant  260 . The anchor  262  includes a head  266  at its proximal end, an intermediate region  268 , and an elongated shaft  270  extending distally from the intermediate region  268 . The head  266  has a generally cylindrical shape and extends generally perpendicularly in proximal direction from the top of the intermediate region  268 . The head  266  includes an exterior threadform  272  configured to engage the locking element  274 . In use, the anchor  262  is placed first, and the fixation aperture  261  is fitted over the head  266 . The head  266  further includes a recess  276  for receiving a portion of an instrument for insertion (for example, a driver). The recess  276  may have any shape that corresponds to the shape of the distal tip of the driver. 
     The intermediate region  268  includes a plurality of vertically-oriented chocks  264  distributed in a radial gear-shaped pattern about the anchor  262 . The chocks  264  are configured to engage with the contoured periphery  263  of a fixation aperture  252  to provide a solid connection between the anchor  262  and implant  260 . The intermediate region  268  further has a sloped distal-facing surface  278  configured to contact the relevant vertebral bodies. The sloped distal-facing surface  278  may have any cross-sectional shape desired by the user, including but not limited to concave, convex, and generally planar. 
     The elongated shaft  270  extends distally from the intermediate region  268 . The shaft  270  includes a threadform  280  configured to provide purchase into the bone. By way of example only, the threadform  280  is provided as a single-lead threadform, however, multiple threads may be used without departing from the scope of the present invention. The shaft  270  further includes a notch  282  to provide the anchor  262  with a self-tapping feature. Further, the anchor  262  may be provided with a lumen  284  extending therethrough such that the anchor  262  is cannulated. The anchor  262  has a major diameter defined by the outer diameter of the threadform  272 . 
       FIGS.  38 - 39    illustrate an example of a locking element  274  for use with the anchor  262 . The locking element  274  includes a central aperture  286  sized and configured to receive the head  266  of the anchor  262  therein. To facilitate this arrangement, the central aperture  286  is provided with a threadform  288  that complements the thread  272  of the head  266 . The upper exterior portion  290  is configured to engage the distal end of an insertion device (for example, an inserter). As best seen in  FIG.  38   , the upper exterior portion  290  has a generally sunburst-shaped cross-section, with a plurality of radial protrusions  292  separated by a plurality of recesses  294 . 
       FIGS.  40 - 41    illustrate the engagement of the locking element  274  with the anchor  262 . To achieve this, the locking element  274  is advanced onto the head  266  of the anchor  262  which extends out of the fixation aperture  242  of the implant  260 . The thread  288  of the locking element  274  cooperates with the head  266  to create a threaded engagement. The locking element  274  may then be rotated in a clockwise direction to advance the locking element  274  onto the head of the anchor  266 . Rotation in a counterclockwise direction could cause the locking element  274  to retreat up into the head  266 , allowing for disengagement and removal if necessary. 
       FIGS.  42 - 48    illustrate an implant  300  according to a sixth example embodiment of a hyper-lordotic implant. The implant  300  shares many similar features with the implants  200 ,  230 ,  248 ,  250 , and  260  such that repeat discussion is not necessary. The implant  300  differs from the implants embodiments described above in that implant is configured for fixed engagement to each or the adjacent vertebral bodies (i.e. V1 and V2). Specifically, the implant  300  includes a tab  304  extending vertically above the top surface of the implant and a second tab  304  extending below the bottom surface of the implant. Each tab  304  includes a fixation aperture  305  for receiving a fixation anchor  302  therethrough to for anchoring into the vertebral bone to secure the placement of the implant. In use, when the implant  300  is positioned within the disc space, the tabs  304  engage the exterior of the upper and lower vertebra and a fixation anchor  302  is driven into the side of each of the upper or lower vertebra. A locking element in the form of a canted coil  306  is also depicted. The canted coil  306  resides in a groove formed within the fixation aperture. A ridge  308  on the head of the anchor  302  has a tapered lower surface and a generally flat upper surface such that the inner diameter of the canted coil  306  expands, due to engagement with the tapered surface of the ridge  308  as the anchor is advanced, allowing the anchor to pass. When the ridge  308  advances past the canted coil  306  the inner diameter of the coil returns to the original dimension, preventing the anchor from backing out of the fixation aperture  305 . 
     The hyper-lordotic implants  200 ,  230 ,  248 ,  250 ,  260 , and  300  have been shown, by way of example, according to a number of embodiments. It should be understood, however, that the description herein of specific embodiments is not intended to limit the scope to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the scope and spirit of the invention as defined herein. By way of example, one will appreciate that the various quantities, sizes, shapes and locking elements/anchors of the tabs described for fixing the implants to the spine, as well as additional possible quantities, sizes, shapes and locking mechanisms/anchors not described, may be combined in any number of different configurations that can provide for a hyper-lordotic implant that can be fixed in position relative to the spine. 
     With reference to  FIG.  49 - 51   , an exemplary insertion instrument  310  is a described. The insertion instrument  310  includes a handle  312 , a thumbwheel housing  314 , an elongate tubular element  316 , an inserter shaft (not shown), and a distal inserter head  318 . 
     The handle  312  is generally disposed at the proximal end of the insertion instrument  310 . The handle  312  may be further equipped with a universal connector to allow the attachment of accessories for ease of handling of the insertion instrument  310  (e.g. a straight handle or a T-handle, not shown). The handle  312  is fixed to the thumbwheel housing  314  allowing easy handling by the user. By way of example, the thumbwheel housing  314  holds at least one thumbwheel  320 , and at least one spacer (not shown). Because the handle  312  is fixed, the user has easy access to the thumbwheel  320  and can stably turn the thumbwheel  320  relative to the thumbwheel housing  314 . Additionally, the relative orientation of the thumbwheel  320  to the handle  312  orients the user with respect to the distal insertion head  318 . The inserter shaft (not shown) is attached to the thumbwheel  320  and is freely rotatable with low friction due to the spacer. The user may then employ the thumbwheel to rotate the inserter shaft thereby advancing it towards the distal inserter head  318 . 
     The elongate tubular element  316  is generally cylindrical and of a length sufficient to allow the device to span from the surgical target site to a location sufficiently outside the patient&#39;s body so the handle  312  and thumbwheel housing  314  can be easily accessed by a surgeon or a complimentary controlling device. The elongate tubular element  316  is dimensioned to receive a spring (not shown) and the proximal end of the inserter shaft into the inner bore  322  of the elongate tubular element  316 . The elongate tubular element  316  is further configured to be snugly received within the inner recess  336  of the snap-fit channel  330  of the guided clip attachment  338  which will be explained in further detail below. The distal inserter head  318  is comprised of a threaded connector  324  and a plate  326 . The threaded connector  324  is sized and dimensioned to be threadably received by the receiving aperture  104 . Further, the plate  326  is sized and dimensioned to be snugly received within the grooved purchase region  106 . 
     According to one example the insertion instrument  310  may be used in combination with a guided clip attachment  328  that engages a retractor blade  38  of the retractor assembly  36  to facilitating proper orientation and positioning of a hyper-lordotic implant, for example hyper-lordotic implant  200  as shown, or any of the various hyper-lordotic implant embodiments described herein. As illustrated in  FIGS.  52 - 54   , the guided clip attachment  328  includes a snap-fit channel  330 , a locking element  332 , and an attachment base  334 . The snap-fit channel  330  contains an inner recess  336  that is generally arch-shaped and is sized and dimensioned to snugly receive at least a portion of the length of the elongate tubular element  316  of the insertion instrument  310 . The snap-fit channel  330  may also be provided with at least one aperture  338  for receiving a ball  346  from the locking element  332  as will be described in greater detail below. The locking element  332  may be comprised of any suitable mechanism for restricting movement of the inserter instrument  310  relative to the guided clip attachment  328 , including but not limited to the ball detent mechanism described. As depicted in  FIG.  52   , the locking mechanism may preferably include a slide lock having a sliding bar  340  with locking rod extensions  342  extending therefrom on either side. The rod extensions  342  each include a detent  343  situated along a portion of the rod extension  342 . The locking rod extensions  342  are situated in and slidable within an inner groove  344  of the locking element  332 . In the unlocked position the detents  345  align with the balls  346  such that the balls  346  may be depressed into the detents  345  (such that they do not extend into the channel  330 ) as the tubular element  316  of the insertion instrument  310  passes the balls  346  during insertion into the channel  330 . In the locked position the balls  346  do not align with the detents  345  and thus cannot be depressed fully into the ball apertures. The balls  346  thus protrude into the channel  330  over the tubular body  316 , preventing removal of the tubular body  316 . 
     In addition to the locking mechanism  332 , one or more ball plungers  348  may also be provided within the snap-fit channel  330  to provide greater stability and control of the guided clip attachment  328  relative to the insertion instrument  310 . The ball plunger  348  may be further provided with a threaded screw  350  surrounding it, thereby creating a spring-loaded ball detent mechanism. The ball-plunger components  348 ,  350  are disposed within, and protrude from, at least one aperture  352  located on the inner recess  336  of the guided clip attachment  328 . When the guided clip attachment  328  is attached to the elongate tubular element  316  of the inserter instrument  310 , the spring-loaded ball components  348 ,  350  retract into the aperture  352  to allow the elongate tubular element  316  to be fully captured while still providing friction between the guided clip attachment  328  and the elongate tubular element  316  portion of the insertion instrument  310 . 
     The guided clip attachment  328  further includes an attachment base  334  for coupling with a retractor blade (e.g. retractor blades,  38 ,  40 , or  42 ) as will be explained below. This attachment provides stability for the implant  200  to be inserted and to prevent the implant  200  from migrating anteriorly during insertion. The attachment base  334  is comprised of a shim  354  and a stabilizing arm  356 . The shim  354  is capable of rotating in two axes via an internal polyaxial joint  358  that allows for cephalad-caudal and anterior-posterior positioning of the implant  328 . Further, the stabilizing arm  356  contains cut-out regions  362  to limit the amount of rotation in the cephalad-caudal directions. The cut-out regions  362  may be sized and figured to allow for any pre-determined amount of rotation between 1 and 359 degrees. According to one example, the cut-outs are configured to allow for rotation within the range of 10 to 30 degrees. Steps  360  engage the ends of the cutout region to prevent further rotation and also rest against the stabilizing arm  356  to prevent lateral rocking of the shim. Alternatively, cutout regions  362  may be removed and the shim may be allowed to rotate 360 degrees. The shim  354  has at least one notch  364  that is sized and dimensioned to snugly mate with the track  46  (specifically the dove tail grooves  48  formed on the interior of retractor blade  42 ) and may travel up and down the length of the retractor blade  38 . 
     According to another example embodiment depicted in  FIGS.  59 - 61   , an inserter instrument  370  that is similar to the inserter  310  except that it is equipped with an integrated guide clip  372  is provided Like the guided clip attachment  328 , the guide clip  372  provides additional stability and positioning assistance during insertion of the implant. The guide clip  372  includes a shim  374  and a stabilizing arm  376 . The shim  354  is capable of rotating in two axes via an internal polyaxial joint (not shown) that allows for cephalad-caudal and anterior-posterior positioning of the implant. The stabilizing arm  376  may contain cut-out regions  378  to limit the amount of rotation in the cephalad-caudal directions. The cut-out regions  378  may be sized and figured to allow for any pre-determined amount of rotation between 1 and 359 degrees. According to one example, the cut-outs are configured to allow for rotation within the range of 10 to 30 degrees. Steps  380  engage the ends of the cutout region to prevent further rotation and also rest against the stabilizing arm  376  to prevent lateral rocking of the shim. Alternatively, cutout regions  378  may be removed and the shim may be allowed to rotate 360 degrees. The shim  374  has at least one notch  382  that is sized and dimensioned to snugly mate with the track  46  (specifically the dove tail grooves  48  formed on the interior of retractor blade  38 ) and may travel up and down the length of the retractor blade  38 . 
     As depicted in the flowchart of  FIG.  62   , one example method for utilizing the systems, implants, and instruments described above is set forth below. A lateral access surgical corridor is formed in the patient (step  400 ), the disc space is prepared (step  402 ), and the anterior longitudinal ligament is resected (step  404 ) as previously explained. Next, at step  406 , a guided clip associated with the insertion instrument (either integral to or removably coupled to) is engaged with the track on a retractor blade used to create the access corridor. The implant is then inserted into the disc space (step  408 ) as the guide clip translates down the track in the retractor blade. Adjustments can be made to the implant in situ as needed while minimizing the likelihood that the implant  200  will be expelled from its optimal position. At step  410  the inserter can be decoupled from the implant  200  and removed from the access corridor. Depending on the type of hyper-lordotic implant selection, an additional step of securing the implant with fixation anchors may also be appropriate. Having been deposited in the disc space, the implant facilitates spinal fusion over time by maintaining the restored curvature as natural bone growth occurs through and/or past the implant, resulting in the formation of a boney bridge extending between the adjacent vertebral bodies. 
     While this invention has been described in terms of a best mode for achieving this invention&#39;s objectives, it will be appreciated by those skilled in the art that variations may be accomplished in view of these teachings without deviating from the spirit or scope of the invention. For example, particularly at L5-S  1  where the pelvic bone makes a lateral access approach difficult, an antero-lateral approach similar to the approach utilized during appendectomies may be utilized.