Patent Publication Number: US-2009234392-A1

Title: Method for inserting a spinal fixation element using implants having guide tabs

Description:
FIELD OF THE INVENTION 
     The present invention relates to spinal fixation and methods for use during orthopedic surgery. More particularly, the present invention relates to inserting a spinal fixation element, such as a rod, using guide tabs extending from bone anchor implanted along a patient&#39;s spine. 
     BACKGROUND OF THE INVENTION 
     Spinal fixation systems may be used in surgery to align, adjust and/or fix portions of a spinal column, i.e., vertebrae, in a desired spatial relationship relative to each other. Many spinal fixation systems employ a spinal rod for supporting the spine and for properly positioning components of the spine for various treatment purposes. Implants, such as vertebral bone anchors, comprising pins, bolts, screws, and hooks, engage the vertebrae and connect the supporting spinal rod to different vertebrae. Spinal rods can be anchored to specific portions of the vertebra. Since each vertebra varies in shape and size, a variety of anchoring devices have been developed to facilitate engagement of a particular portion of the bone. 
     Pedicle screw assemblies, for example, have a shape and size that is configured to engage pedicle bone. Such screws typically include a threaded shank that is adapted to be threaded into a vertebra, and a head portion having a spinal fixation element-receiving portion, which, in spinal rod applications, is usually in the form of a U-shaped slot formed in the head portion for receiving the rod. A set-screw, plug, cap or similar type of closure mechanism is used to lock the rod into the rod-receiving portion of the pedicle screw. 
     In conventional spinal surgery, first, anchoring devices are attached to vertebra, and then a spinal rod is aligned with the anchoring devices and secured. For example, for conventional pedicle screw assemblies, first the engagement portion of each pedicle screw is threaded into a vertebra. Once the pedicle screw assembly is properly positioned, a spinal fixation rod is connected in the rod-receiving portion of each pedicle screw head. The rod is locked into place by tightening a cap or similar type of closure mechanism to securely interconnect each pedicle screw to the fixation rod. This type of conventional spinal surgical technique usually involves making a surgical access opening in the back of the patient that is almost as long as the length of the spinal rod to be implanted. Because exact placement of the screw assemblies depends on a patient&#39;s particular bone structure and bone quality, the exact position of all screw assemblies cannot be known until after all the assemblies are positioned. Adjustments, such as bending, are made to the spinal rod to ensure that it aligns with each screw assembly. 
     Recently, the trend in spinal surgery has been moving toward providing minimally invasive surgical (MIS) devices and methods for implanting spinal fixation elements. In minimally invasive surgical techniques, the anchors and rod are typically inserted through small incisions. For example, the anchors and rod may be delivered percutaneously to an implant site through a small access port such as a cannula. In other methodologies, a mini-open technique may be used to place the spinal fixation system. 
     However, such minimally invasive procedures introduce other issues. Because the bone anchors and spinal fixation element are inserted through small incisions, such as percutaneously, there is reduced visibility of the surgical site. Placement of the spinal fixation element becomes more difficult when there is no direct view of the surgical site. Thus, what is needed is a means for being able to accurately insert a spinal fixation element along a patient&#39;s spine when using minimally invasive surgical techniques. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention provide methods for inserting a spinal fixation element using minimally invasive surgical techniques. The methods use implants having guide tabs. The guide tabs are used to locate the spinal fixation element along a patient&#39;s spine. The guide tabs may be orientated in different ways to accommodate different insertion techniques for the spinal fixation element. 
     In accordance with one aspect, a method is provided for inserting a spinal fixation element along a patient&#39;s spine, the method involves inserting a first implant having a guide tab into a first vertebra. A second implant having a guide tab may then be inserted into a second vertebra. The spinal fixation element may then be inserted using the guide tabs of the first and second implants to locate the spinal fixation element along the patient&#39;s spine. 
     In other embodiments, the spinal fixation element may be inserted before the first or second implant. After the implants are inserted, the spinal fixation element may be moved into position using the guide tabs to locate the spinal fixation element along the patient&#39;s spine. 
     In certain embodiments, the bone anchor is an anchor bolt. The anchor bolt has a bone engagement portion; a threaded head portion for receiving a locking member; and a rod connector body disposed between the bone engagement portion and the threaded head portion for connector bodying a rod. In certain embodiments the anchor bolt may include a detachable extension shaft that extends from the threaded head portion opposite the bone engagement portion. 
     In accordance with another aspect, a method is provided for inserting a spinal fixation element along a patient&#39;s spine. The method involves percutaneously inserting a first implant having a guide tab into a first vertebra. A second implant having a guide tab may then be percutaneously inserted into a second vertebra. The guide tabs of the first and second implants may then be orientated to define a channel along the patient&#39;s spine for receiving the spinal fixation element. The spinal fixation element may then be percutaneously inserted within the channel defined by the guide tabs of the first and second implants to locate the spinal fixation element along the patient&#39;s spine. 
     In accordance with another aspect, a method is provided for inserting a spinal fixation element along a patient&#39;s spine. The method involves making a mini-open incision along the patient&#39;s spine. A first implant having a guide tab may then be inserted, through the mini-open incision, into a first vertebra proximal to a first end of the mini-open incision. A second implant having a guide tab may then be inserted, through the mini-open incision, into a second vertebra proximal to a second end of the mini-open incision. The guide tabs may then be orientated to receive and guide the ends of the spinal fixation element. The spinal fixation element may then be inserted between the guide tabs, wherein the guide tabs of the first and second implants receive the first and second ends of the spinal fixation element and guide the insertion of the spinal fixation element along the patient&#39;s spine. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       These and other features and advantages of the mechanisms and methods disclosed herein will be more fully understood by reference to the following detailed description in conjunction with the attached drawings in which like reference numerals refer to like elements through the different views. The drawings illustrate principles of the instruments and methods disclosed herein and, although not to scale, show relative dimensions. 
         FIG. 1A  illustrates an exploded view of components of an implant in accordance with aspects of the present invention; 
         FIG. 1B  illustrates an assembled view of components of an implant in accordance with aspects of the present invention; 
         FIG. 2  is a flow chart of one exemplary method in accordance with aspects of the present invention; 
         FIG. 3A  is a posterior view of six percutaneous incisions formed in the thoracolumbar fascia of a patient&#39;s back; 
         FIG. 3B  is an end view showing a blunt dissection of the muscles surrounding a patient&#39;s vertebra; 
         FIG. 3C  is an end view of the vertebra in  FIG. 3B  with a k-wire placed through the incision and into the patient&#39;s vertebra; 
         FIG. 3D  is an end view of the vertebra in  FIG. 3C  showing an obturator and several dilators disposed over the k-wire to dilate the tissue and muscles; 
         FIG. 4  illustrates an exemplary embodiment of implants inserted in accordance with aspects of the present invention; 
         FIG. 5A  illustrates an exemplary embodiment of the insertion of the spinal fixation element in accordance with aspects of the present invention; 
         FIG. 5B  illustrates an exemplary embodiment of a spinal fixation element inserted in accordance with aspects of the present invention; 
         FIG. 6A  illustrates an exemplary embodiment of inserted implants in an alternate orientation in accordance with aspects of the present invention; 
         FIG. 6B  illustrates an exemplary embodiment of the manipulation of a spinal fixation element using the guide tabs of the implants in accordance with aspects of the present invention; 
         FIG. 7  illustrates an exemplary embodiment of the connecting of the spinal fixation element to the implants using closing mechanism in accordance with aspects of the present invention; 
         FIG. 8  is a flow chart of another exemplary method in accordance with aspects of the present invention; 
         FIG. 9  is a flow chart of another exemplary method in accordance with aspects of the present invention 
         FIG. 10  illustrates an exemplary embodiment of the insertion of the implants and spinal fixation element using a mini-incision surgical technique. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the adaptable clamping mechanisms and methods disclosed herein. Examples of these embodiments are illustrated in the accompanying drawings. Those of ordinary skill in the art will understand that the methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention. 
     As discussed above, embodiments of the present invention provide methods for inserting a spinal fixation element using minimally invasive surgical techniques. The implants used in exemplary embodiments have a guide tab which is used to locate the spinal fixation element along the patient&#39;s spine. Exemplary embodiments described herein concern implants for securing spinal fixation elements and methods of use. As such, exemplary embodiments of implants are formed of suitable materials for use in a human body. Suitable materials include, but are not limited to, stainless steel, titanium, or the like. Exemplary embodiments of implants are sized and dimensioned for insertion through a minimally invasive surgical access port, such as a cannula. 
     An example of one embodiment of a suitable implant can be seen in  FIGS. 1A and 1B .  FIG. 1A  depicts a perspective view showing the individual parts of the implant  100 .  FIG. 1B  depicts a perspective view showing the implant  100  assembled. In this example, the implant  100  includes a bone anchor  110 , a connector body  120 , and a detachable guide tab  130 . 
     The bone anchor  110  comprises a joint portion, illustrated as a proximal anchor head  112 , for coupling the bone anchor  110  to the connector body  120  and an anchoring portion, illustrated as a distal shaft  114  configured to engage bone. The distal shaft  114  of the bone anchor  110  extends along a longitudinal axis  116 . The distal shaft  114  may include one or more bone engagement mechanisms to facilitate gripping engagement of the bone anchor to bone. In the illustrated embodiment, the distal shaft  114  includes an external thread  118  extending along at least a portion of the shaft for engaging bone. In the illustrated embodiment, the external thread  118  is a single lead thread that extends from a distal tip  119  of the shaft to the anchor head  112 , though one skilled in the art will recognize that the external thread may extend along any selected portion of the shaft and have any suitable number of leads. Other suitable bone engagement mechanisms include, but are not limited to, one or more annular ridges, multiple threads, dual lead threads, variable pitched threads and/or any conventional bone engagement mechanism. 
     The anchor head  112  of the bone anchor  110  may be configured to facilitate adjustment of the bone anchor  110  relative to the connector body  120  of the implant  100 . For example, the illustrative anchor head  112  may be substantially spherical to permit pivoting of the bone anchor  110  relative to the connector body  120  in one or more selected directions. In some embodiments, the anchor head  112  may also have surface texturing, knurling and/or ridges. 
     In this example, the connector body  120  forms a seat  124  for receiving a spinal fixation element. A cavity  122  passes through the connector body  120  and is configured for receiving the bone anchor  110  and engaging the proximal head  112  of the bone anchor  110 . 
     The connector body  120  receives the proximal head  112  of the bone anchor in the cavity  122  to couple the bone anchor  110  thereto. An example of this can be seen in  FIG. 1B . The connector body  120  receives a spinal fixation element in the seat  124  defined by the connector body  120 , thereby coupling the spinal fixation element engaged by the connector body  120  to the bone anchor  110 . 
     The cavity  122  of the connector body  120  is configured to interact with the spherical shape of the proximal head  112  of the bone anchor  110  to allow the bone anchor  110  to rotate and pivot independently of the connecter body  120  providing a polyaxial implant  100 . Likewise, once the distal shaft  114  of the bone anchor  110  has been implanted in a bone (not shown) the interaction of the cavity  122  and proximal head  112  allow the connecter body  120  to be positioned to engage a spinal fixation element (not shown). 
     The detachable guide tab  130  extends from the connector body  120  in the longitudinal axis  116  opposite and offset of the distal shaft  114  of the bone anchor  110 . Having the guide tab  130  offset provides reduced access to the proximal head  112  of the bone anchor  110  for inserting and potentially re-adjusting the height of the bone anchor  110 . This is particularly beneficial in longer segment constructs where the bone anchor heights may need to be adjusted to match the curve of the spinal fixation element. Having one offset tab allows adjustment with the spinal fixation element not having to be removed from the site, rather just shifted lateral to the tab. Having the guide tab  130  offset also allows for side and top loading of a spinal fixation element (not shown) upon the seat  124  while still providing a guide for locating the spinal fixation element (not shown). 
     The detachable guide tab  130  is configured to extend outside the patient through the patient&#39;s skin while providing clear access to the connector body  120  and the proximal head  112  of the bone anchor  110 . Accordingly, the guide tab  130  may form a partial cannula extending through the skin wherein the guide tab has a crescent shaped cross section. In some embodiments, additional components could be mated to the guide tab to more fully enclose the access site. In certain embodiments, the detachable guide tab  130  has a break-away feature  132  that may be fragile or weakened allowing the detachable guide tab  130  to be detached and removed. Alternatively, the detachable guide tab  130  can be detached by cutting the guide tab away from the implant  100 . In still other embodiments, a secondary support could be used in conjunction with the guide tab to provide additional strength until breaking and removal is required. Other possible configurations and techniques will be apparent to one skilled in the art given the benefit of this disclosure. For example, the strength of the tab could be varied to provide enough force to maneuver the bone anchor and the spinal fixation elements together thereby potentially correcting spinal vertebral segments by adjusting their relative positions. The guide tabs may also be flexible to allow easier access of instrumentation and less crowding in the incisions. Alternatively, the guide tabs may also be a combination of stiffness. For example, the distal end could be stronger to provide the strength required for adjustments, while the proximal end exiting the skin incision could be flexible or malleable. 
     In certain embodiments, the detachable guide tab  130  may have one or more surface configurations  134  for engaging tools, spinal fixation elements, and/or closure mechanisms to further assist in the insertion and guidance of the tools, spinal fixation elements, and/or closure mechanisms. The surface configurations  134  may be one or more tracks on the guide tab  130 . In some such embodiments, the tracks may be keyed to mate with specific tools, spinal fixation elements, and/or closure mechanisms. Other possible configurations and techniques will be apparent to one skilled in the art given the benefit of this disclosure. 
       FIG. 2  depicts a flow diagram  200  of one embodiment for inserting a spinal fixation along the patient&#39;s spine in a minimally invasive surgery (MIS). The method involves using two or more implants having guide tabs, such as described above, to assist in the placement of the spinal fixation element. A first implant is inserted into a first vertebra of the patient&#39;s spine (Step  210 ). A second implant may then be inserted into a second vertebra of the patient&#39;s spine (Step  220 ). Additional implants may also be inserted as desired. A spinal fixation element, such as a rod, may then be inserted using the guide tabs of the inserted first and second implants to locate the spinal fixation element along the patients spine (Step  230 ). Each of these steps will be discussed in further detail below. 
     It should be understood that the steps set forth above are provided in one possible order, the steps can be performed in any order, for example, the spinal fixation element may be inserted into the patient before either the first and/or second implant. If the implants are inserted after the spinal fixation element, the guide tabs of the implants can still be used to locate the previously inserted spinal fixation element along the patient&#39;s spine. 
     In certain embodiments, the method may further include additional steps. After insertion, the spinal fixation element may be further manipulated using the guide tabs of the first and second implants (step  240 ). Once the implants and spinal fixation element have been inserted (and manipulated), closure mechanisms may be inserted to connect the spinal fixation element to the implants. In the example of  FIG. 2 , a first closure mechanism may be inserted to connect the spinal fixation element to the first implant (Step  250 ). A second closure mechanism may also be inserted to connect the spinal fixation element to the second implant (Step  160 ). Additional closure mechanism may further be inserted to connect the spinal fixation element to any additionally inserted implants as desired. Each of these steps will be discussed in further detail below. 
     In other embodiments, once the spinal fixation element has been connected to the implants, the guide tabs may be removed. In the example of  FIG. 1 , the guide tab the first implant may be detached from the first implant (Step  270 ) and the guide tab of the second implant may be detached from the second implant (Step  280 ). Additional guide tabs may further detached from any additionally inserted implants. Each of these steps will be discussed in further detail below. 
     Various techniques can be used to insert the first and second implants (steps  210  and  220 ). For example, a minimally invasive percutaneous incision  302  may be made through the tissue at one or more sites as shown in  FIGS. 3A-D . The location, shape, and size of the incision  302  will depend on the type and quantity of rod anchor systems being implanted, as well as the technique being employed to implant the rod anchor systems. By way of non-limiting example,  FIG. 3A  illustrates three minimally invasive percutaneous incisions  302   a - c  formed on one side of three adjacent vertebra in the thoracolumbar fascia in the patient&#39;s back, and three additional minimally invasive percutaneous incisions  302   d - f  formed on the opposite side of the three adjacent vertebra in the thoracolumbar fascia in the patient&#39;s back. 
     In certain exemplary embodiments, one or more of the incisions may be expanded to create a pathway from the incision  302  to proximate a vertebra  300 . For example, the incision  302  may be expanded by serial dilation, with a retractor such as an expandable retractor, or by any other conventional techniques. In one exemplary embodiment, blunt finger dissection can be used, as shown in  FIG. 3B , to separate the longissimus thoracis  310  and multifidus muscles  312 , thereby exposing the facet and the junction of the transverse process and superior articular process  314 . 
     An implant may be inserted through one or more of the incisions and the pathways to proximate the vertebra  300 . Any technique for inserting an implant can be used. In one embodiment, for example, an implant can be inserted over a guidewire, such as a k-wire. As shown in  FIG. 3C , a guide wire, e.g., a k-wire  304 , can be inserted, either prior to or after formation of the incision  302 , at each implant site. The k-wire  304  may extend into the vertebra  300  at the desired entry point of the implant. In certain exemplary embodiments, the k-wire may be advanced into the vertebra  300 . In other exemplary embodiments, the k-wire may be positioned proximate to or against the vertebra  300 . Fluoroscopy or other imaging may be used to facilitate proper placement of the k-wire  304 . The incision  302  may be dilated to provide a pathway for delivery of an implant to each site, in the manner discussed above, before or after placement of the guidewire. For example,  FIG. 3D  illustrates serial dilation at one end of the incision  302  using an obturator  306   a  having several dilators  306   b,    306   c  of increasing size placed there over. The dilators  306   b,    306   c  are delivered over the obturator  306   a  and k-wire  304  to essentially stretch the skin around the incision  302  and to expand the pathway to the implant site. One skilled in the art will appreciate that an implant may be advanced to a vertebra through the incision without the need for a guidewire. 
     Once the incision  302  is dilated to the proper size, if necessary, the vertebra  300  may be prepared using one or more bone preparation instruments, such as drills, taps, awls, burrs, probes, etc. In certain exemplary embodiments, one or more cannulae can be used to provide a pathway from the incision  302  to the anchor site for insertion of the bone preparation instruments and/or the anchor. In an exemplary embodiment, a relatively small cannula (not shown) may be used to introduce bone preparation instruments into the surgical site. Once the vertebra  300  is prepared, an implant can be delivered along the k-wire, either through the cannula, or after the cannula is removed, and implanted in the vertebra  300 . Alternatively, in embodiments not employing a guidewire, the implant may be advanced through the incision, e.g., through a cannula, to the vertebra  300 . A cannula, retractor, or other instrument may be employed to guide the implant to the vertebra  800 . 
     The implants may be oriented in a number of ways to assist in the insertion and targeting of a spinal fixation element.  FIG. 4  depicts one such orientation wherein the first implant  100   a  and the second implant  100   b  have inserted into a first vertebra  410   a  and a second vertebra  410   b  of the patients spine  400 . In this example, the bone anchors of the first implant  100   a  and second implant  100   b  have been inserted into the first  410   a  and second vertebra  410   b  and the connector bodies  120   a  and  120   b  defining the seats  124   a  and  124   b  have been orientated so that the guide tabs  130   a  and  130   b  will be on the same side of a spinal fixation element (not shown) placed on the seats  124   a  and  124   b.  This orientation allows for top and side loading of a spinal fixation element onto the seats  124   a  and  124   b.    
     A variety of techniques can be used to insert a spinal fixation element, such as a rod, to extend along a patient&#39;s spine (step  230 ). The spinal fixation element may also be introduced at various locations along the patient&#39;s spine. For example, the spinal fixation element can be introduced through the same incision used to introduce an implant, or alternatively the spinal fixation element can be introduced through an incision that is separate from and located a distance apart from the incisions used to insert the implants. The spinal fixation element may be inserted before or after the implants. The spinal fixation element can also either be directly introduced through the incision to extend up along the patient&#39;s spinal column, or it can be introduced through a cannula, access port, or along the guide tab  130  of an implant  100  for guiding the spinal fixation element to extend along the patient&#39;s spinal column. Various tools can also be coupled to the spinal fixation element to manipulate and facilitate introduction and positioning of the spinal fixation element in the patient&#39;s body. The techniques for the percutaneous insertion of a spinal fixation element are similar to those for inserting implants as discussed above. 
     In one exemplary embodiment, the guide tabs  130   a  and  130   b  of the first and second implants  100   a  and  100   b  may be used to guide the spinal fixation element into location along the patient&#39;s spine. As discussed above, the guide tabs  130   a  and  130   b  of the first and second implants  100   a  and  100   b  form partial cannulae through the patient&#39;s skin to the implant site. Accordingly, the insertion of the first and second implants  100   a  and  100   b  serve to provide the incisions used to insert the first and second implants  100   a  and  100   b  with an access port, via the partial cannulae formed by the guide tabs  130   a  and  130   b,  for the insertion of a spinal fixation element. 
       FIG. 5A  depicts an exemplary embodiment wherein a spinal fixation element  500  is introduced through the same incision as used for the first implant  100   a  using the guide tab  130  of the first implant to direct the spinal fixation element to the target site. In this example, the spinal fixation element  500  is a rod. One end of the rod has a tapered tip  510  to aid in the insertion of the rod  500 . The rod also possesses a curve along the length of the rod  500  to assist in the insertion and transition of the rod  500  from a substantially vertical orientation along the guide tab  130   a  to a substantially horizontal orientation along the patient&#39;s spine  400 . An example of the rod  500  in a substantially horizontal orientation along a patient&#39;s spine can be seen in  FIG. 5B . 
     It should be noted that the spinal fixation element  500  need not be introduce though one of the incisions used to insert an implant  100 . The spinal fixation element  500  may be introduced through a separate incision. In certain embodiments, the spinal fixation element  500  may be inserted remotely and then the first implant  100   a  and second implant  100   b  may be inserted. Alternatively, the first implant  100   a  and the second implant  100   b  may be inserted and then the spinal fixation element  500  may be inserted. 
     Once the first  100   a  and second  100   b  implant have been inserted, the spinal fixation element  500  may then be positioned onto the seats  124   a  and  124   b  of the first  100   a  and second  100   b  implants. In the example of  FIG. 5B , the guide tabs  130   a  and  130   b  are orientated to allow the spinal fixation element  500  to be side loaded onto the seats  124   a  and  124   b  opposite the guide tabs  130   a  and  130   b.  Other orientations of the guide tabs are also possible to assist in the insertion and location of the spinal fixation element  500 . 
       FIG. 6A  depicts one embodiment of an alternate orientation of guide tabs  130   a  and  130   b  used in the insertion of a spinal fixation element  500 . In this example, the guide tabs  130   a  and  130   b  are orientated so as to be on opposite sides of an inserted spinal fixation element  500 . Thus, in effect, the guide tabs  130   a  and  130   b  define a channel  600  along the patient&#39;s spine  400 . Inserting the spinal fixation element  500  in the channel  600  defined by the first guide tab  130   a  and second guide tab  130   b  ensures that the spinal fixation element will be positioned on the seats  124   a  and  124   b  of the first  100   a  and second  100   b  implants and located along the patient&#39;s spine  400 . 
     In certain embodiments, once a spinal fixation element  500  has been inserted, further adjustments may be required. As such, the guide tabs  130   a  and  130   b  may be used to manipulate the position of the spinal fixation device  500  (step  240 ). An example of this can be seen in  FIG. 6B . 
     As discussed above, the implants  100   a  and  100   b  are polyaxial in nature wherein the connector bodies  120   a  and  120   b  are pivotable around the proximal heads  112   a  and  112   b  of the bone anchors  110   a  and  110   b.  As such, the connector bodies  120   a  and  120   b  may be pivoted around the proximal heads  112   a  and  112   b  to adjust the guide tabs  130   a  and  130   b  to different orientations as desired. As the guide tabs  130   a  and  130   b  extend outside the patient, the guide tabs  130   a  and  130   b  provide a convenient means for manipulating the position of the connector bodies  120   a  and  120   b  to which the guide tabs  130   a  and  130   b  are attached. In the example of  FIG. 6B , since the guide tabs  130   a  and  130   b  are orientated to be on both sides of the spinal fixation element, the guide tabs  130   a  and  130   b  also provide a means to manipulate the spinal fixation element  500 . In this embodiment, the guide tabs  130   a  and  130   b  may be rotated, pivoted, or otherwise moved by the surgeon to come in contact with the spinal fixation element  500  and thereby manipulate the spinal fixation element  500  as desired. 
     Once the spinal fixation element  500  has been inserted and positioned as desired, the spinal fixation element  500  may then be connected to the implants  100   a  and  100   b  to fix the position of the spinal fixation element  500 . To achieve this, closure mechanisms are used. 
     An example using closure mechanisms can be seen in  FIG. 7 . In this embodiment, a first closure mechanism  700   a  is inserted using the guide tab  130   a  of the first implant  100   a.  A second closure mechanism  700   b  is also inserted using the guide tab  130   b  of the second implant  100   b.    
     If the implant  100   a  and  100   b  where inserted percutaneously, as describe above, the closure mechanisms  700   a  and  700   b  may be inserted through the same incisions used to insert the implant  100   a  and  100   b.  In certain embodiments, the closure mechanism  700   a  and  700   b  are configured to engage the surface configurations  134   a  and  134   b  of the guide tabs  130   a  and  130   b.  For example, the closure mechanisms  700   a  and  700   b  may be keyed to ride in rails provide by the surface configurations  134   a  and  134   b.  Thus, the closure mechanisms  700   a  and  700   b  may be slide along the guide tabs  130   a  and  130   b  from outside the patient to the connector body  120  inside the body to capture the spinal fixation element  500 . 
     Once the spinal fixation element  500  has been captured by the closure mechanisms  700   a  and  700   b,  the closure mechanisms  700   a  and  700   b  may be secured using locking mechanisms  710   a  and  710   b.  In the example of  FIG. 7 , the locking mechanisms  710   a  and  710   b  are set screws. In this example the set screws  710   a  and  710   b  have been preset into the closure mechanisms  700   a  and  700   b.  Thus, the set screws  710   a  and  710   b  just require tightening using a driver (not shown) to secure the spinal fixation element  500 . 
     Once the spinal fixation element  500  has been connected to the implants  200   a  and  200   b  using the closure mechanisms  700   a  and  700   b  (steps  250  and  260 ), the guide tabs  130   a  and  130   b  of the implants  100   a  and  100   b  may be detached and removed In the case of the embodiments set forth above, this involves detaching the first guide tab  130   a  from the first implant  100   a  (step  270 ) and detaching the second guide tab  130   b  from the second implant  100   b  (step  280 ). As discussed previously, the guide tabs  130   a  and  130   b  of the implants  100   a  and  100   b  may include fragile or weakened or otherwise breakaway features  132   a  and  132   b  allowing for easier detachment and removal. 
     While the exemplary embodiment of  FIG. 2  depicts a generic method of the present invention, it should be understood that the methodology may be adjusted to reflect particular insertion techniques. Some examples of other embodiments of methodologies can be seen in  FIGS. 8 and 9 . 
       FIG. 8  depicts a flow diagram  800  of one exemplary embodiment wherein the implants and spinal fixation element are percutaneously inserted using the techniques described above with the implants orientated as seen in  FIGS. 6A and 6B . A first implant is percutaneously inserted into a first vertebra of the patient&#39;s spine (Step  810 ). A second implant may then be percutaneously inserted into a second vertebra of the patient&#39;s spine (Step  820 ). The techniques for percutaneous insertion are discussed above in reference to  FIGS. 3A-D . 
     The guide tabs of the first and second implants may then be orientated to define a channel along the patient&#39;s spine for receiving the spinal fixation element (step  830 ). This orientation is described above in reference to  FIGS. 6A and 6B . Additional implants may also be inserted and orientated as desired. 
     A spinal fixation element, such as a rod, may then be percutaneously inserted within the channel defined by the guide tabs of the first and second implants to locate the spinal fixation element along the patient&#39;s spine (Step  840 ). This was also discussed above in regard to  FIGS. 6A and 6B . 
     As with the method of  FIG. 1 , in certain embodiments, the method of  FIG. 8  may include additional steps. After insertion, the spinal fixation element may be further manipulated using the guide tabs of the first and second implants (step  850 ). Once the implants and spinal fixation element have been inserted (and manipulated), closure mechanisms may be inserted to connect the spinal fixation element to the implants. In the example of  FIG. 8 , a first closure mechanism may be percutaneously inserted to connect the spinal fixation element to the first implant (Step  860 ). A second closure mechanism may also be percutaneously inserted to connect the spinal fixation element to the second implant (Step  870 ). It should be understood that the techniques discussed above in regard to  FIG. 7  may performed on implants having the orientation shown in  FIGS. 6A and 6B . Additional closure mechanism may further be inserted to connect the spinal fixation element to any additionally inserted implants as desired. 
     In other embodiments, once the spinal fixation element has been connected to the implants, the guide tabs may be removed. In the example of  FIG. 8 , the guide tab the first implant may be detached from the first implant (Step  880 ) and the guide tab of the second implant may be detached from the second implant (Step  890 ). Additional guide tabs may further detached from any additionally inserted implants. 
     While the previous examples dealt primarily with percutaneous insertion, it should be understood the method may be practiced using other types of insertion techniques may be used. One possible alternative exemplary embodiment can be seen in  FIGS. 9 and 10 . 
       FIG. 9  depicts a flow diagram  900  of one exemplary embodiment wherein the implants and spinal fixation element are inserted through a mini-open incision. First a mini-open incision is made along the patient&#39;s spine (step  910 ). A first implant may then be inserted through the mini-open incision into a first vertebra (step  920 ). A second implant may then be inserted through the mini-open incision into a second vertebra (step  930 ). The guide tabs of the first and second implants may then be orientated to receive and guide the spinal fixation element (step  940 ). Once the guide tabs are properly orientated, the spinal fixation element may inserted through the mini-incision along the guide tabs of the first and second implants (step  950 ) Each of these steps will be described in more detail below. 
     In certain embodiments, the method may further include additional steps. After insertion, the spinal fixation element may be further manipulated using the guide tabs of the first and second implants (step  960 ). Once the implants and spinal fixation element have been inserted (and manipulated), closure mechanisms may be inserted to connect the spinal fixation element to the implants. In the example of  FIG. 9 , a first closure mechanism may be inserted to connect the spinal fixation element to the first implant (Step  970 ). A second closure mechanism may also be inserted to connect the spinal fixation element to the second implant (Step  980 ). Additional closure mechanism may further be inserted to connect the spinal fixation element to any additionally inserted implants as desired. Each of these steps will be discussed in further detail below. 
     In other embodiments, once the spinal fixation element has been connected to the implants, the guide tabs may be removed. In the example of  FIG. 9 , the guide tab the first implant may be detached from the first implant (Step  990 ) and the guide tab of the second implant may be detached from the second implant (Step  1000 ). Additional guide tabs may further detached from any additionally inserted implants. Each of these steps will be discussed in further detail below. 
     A mini-incision is a minimally invasive surgical (MIS) technique in which a small incision on the patient along the spine is used to insert the implants and spinal fixation element. The incision is larger than used for percutaneous insertion but smaller than used in traditional techniques. In traditional techniques the incision may be span the entire of the patient&#39;s spine while a mini incision may just span the distance between two vertebrae on the patient&#39;s spine. An example of this can be seen in  FIG. 10 . 
     In  FIG. 10 , a mini incision  1010  is made spanning between a first  410   a  and second  410   b  vertebra of the patient&#39;s spine  400 . (step  910 ). A first implant  100   a  has been inserted through the mini-incision  1010  into the first vertebra  410   a  and a second implant  200   b  has been inserted through the mini-incision  1010  into the second vertebra  410   b  (steps  920  and  930 ). In certain embodiments, the first implant  100   a  is located proximate to a first end  1020  of the mini-incision  1010  while the second implant  100   b  is located proximate to a second end  1030  of the mini-incision  1010  such that the guide tabs  130   a  and  130   b  of the implants  100   a  and  100   b  extend outside of the patient and help define the opening of the mini-incision  1010 . 
     In the example of  FIG. 10 , the first guide tab  130   a  and second guide tab  130   b  have been orientated (step  940 ) to be at opposite ends of an inserted spinal fixation element  500 . The spinal fixation element  500  may then be inserted through the mini-incision  1010  between the guide tabs  130   a  and  130   b  (step  950 ) as shown in  FIG. 10 . Here, the partial cannula shape and surface configuration  134   a  and  134   b  of the guide tabs  130   a  and  130   b  serve to engage and guide the spinal fixation element into location along the patient&#39;s spine. It should be understood however, that  FIG. 10  depicts one possible orientation. The guide tabs may also be orientated as seen in  FIGS. 4-7  or any other orientation when using a mini-incision technique. 
     The steps of manipulation (step  960 ), inserting closure mechanisms (steps  970  and  980 ), and removing the guide tabs (steps  990  and  1000 ) may then be performed as discussed above. It will be apparent to one skilled in the art that the techniques and device discussed above for these steps can be modified for the particular orientation and insertion technique shown in  FIG. 10  without departing from the spirit and scope of the invention. 
     One skilled in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the invention is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety. 
     While the methods and instruments of the present invention have been particularly shown and described with reference to the exemplary embodiments thereof, those of ordinary skill in the art will understand that various changes may be made in the form and details herein without departing from the spirit and scope of the present invention. Those of ordinary skill in the art will recognize or be able to ascertain many equivalents to the exemplary embodiments described specifically herein by using no more than routine experimentation. Such equivalents are intended to be encompassed by the scope of the present invention and the appended claims.