Abstract:
An exemplary surgical instrument for inserting a spinal implant includes an inserter portion, a coupling member, a first actuator, and a second actuator. The inserter portion includes at a proximal end a receiving block, at a distal end a sleeve, and a channel extending therethrough. The coupling member includes at a proximal end movably coupled with the receiving block, a middle portion that slides within the channel, a distal end that couples the spinal implant, and a first axial bore extending therethrough. The first actuator includes a proximal end with a first projection for engaging the receiving block, a first shaft extending through the first axial bore, and a distal end with a first engagement feature for engaging a first deployment feature of the implant. The second actuator includes a proximal lend with a second projection for engaging the receiving block, a second shaft extending through a second axial bore of the first shaft, and a distal end with a second engagement feature for engaging a second deployment feature of the implant.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation-in-part of U.S. patent application Ser. No. 12/944,507 to Patel et al. filed Nov. 11, 2010, which claims priority to U.S. Provisional Application 60/260,323 to the same inventors filed Nov. 11, 2009, both incorporated by reference in their entirety. 
     
    
     FIELD 
       [0002]    The present disclosure generally relates to the field of spinal orthopedics, and more particularly to instruments for insertion and deployment of features of an implant. 
       BACKGROUND 
       [0003]    The spine is a flexible column formed of a plurality of bones called vertebra. The vertebrae are hollow and piled one upon the other, forming a strong hollow column for support of the cranium and trunk. The hollow core of the spine houses and protects the nerves of the spinal cord. The different vertebrae are connected to one another by means of articular processes and intervertebral, fibrocartilaginous bodies. 
         [0004]    The intervertebral fibro-cartilages are also known as intervertebral disks and are made of a fibrous ring filled with pulpy material. The disks function as spinal shock absorbers and also cooperate with synovial joints to facilitate movement and maintain flexibility of the spine. When one or more disks degenerate through accident or disease, nerves passing near the affected area may be compressed and are consequently irritated. The result may be chronic and/or debilitating back pain. 
         [0005]    Various methods and apparatus have been designed to relieve such back pain, including spinal fusion using an interbody spacer or suitable graft using techniques such as Anterior Lumbar Interbody Fusion (ALIF), Posterior Lumbar Interbody Fusion (PLIF), or Transforaminal Lumbar Interbody Fusion (TLIF) surgical techniques. The implants used in these techniques, also commonly referred to as vertebral body replacements (VBR) devices, are placed in the interdiscal space between adjacent vertebrae of the spine. Many times an exterior plate is used in conjunction with the VBR to hold the adjacent vertebrae while the fusion occurs. Some implants may include features for attachment to the vertebrae. These features may be deployed using one or more instruments. 
       SUMMARY 
       [0006]    An exemplary surgical instrument for inserting a spinal implant includes an inserter portion, a coupling member, a first actuator, and a second actuator. The inserter portion includes at a proximal end a receiving block, at a distal end a sleeve, and a channel extending therethrough. The coupling member includes at a proximal end movably coupled with the receiving block, a middle portion that slides within the channel, a distal end that couples the spinal implant, and a first axial bore extending therethrough. The first actuator includes a proximal end with a first projection for engaging the receiving block, a first shaft extending through the first axial bore, and a distal end with a first engagement feature for engaging a first deployment feature of the implant. The second actuator includes a proximal lend with a second projection for engaging the receiving block, a second shaft extending through a second axial bore of the first shaft, and a distal end with a second engagement feature for engaging a second deployment feature of the implant. 
         [0007]    In other features, the receiving block includes features for limiting rotational movement of at least one of the first actuator and the second actuator. The receiving block includes an initial slot on the circumferential surface at a first radius from a longitudinal axis of the instrument. The initial slot transitions to a ramped portion of increasing radius. The ramped portion terminates at a second radius that is great than the first radius. The ramped portion transitions to a deployed slot at a radius less than the second radius. The first projection is configured to engage at least one of the initial slot, the ramped portion, and the deployed slot during actuation of the first deployment feature of the implant. 
         [0008]    In still other features, the proximal end of the first actuator includes a receiving end with features for limiting rotational movement of at least one of the first actuator and the second actuator. The receiving end includes a first notch on the circumferential surface at a first angle relative to a first handle assembly. The receiving end includes a second notch disposed at a second angle relative to the first handle assembly. The receiving end includes a ramped portion between the first notch and the second notch. 
         [0009]    In yet other features, the instrument includes a release mechanism that forces the first actuator and the second actuator apart. The release mechanism includes a lever arm and a cam portion coupled with the second actuator such that rotation of the lever arm applies force through the cam portion on the first actuator. 
         [0010]    In still yet other features, the coupling member includes a pair of arms at the distal end for clamping the spinal implant. The first actuator rotates in a first direction to deploy the first deployment feature and the second actuator rotates in a second direction to deploy the second deployment feature. The distal end of the first shaft and the distal end of the second shaft includes at least one of a splined projection and a hexagonal projection. 
         [0011]    An exemplary system for a spinal procedure includes an implant and an instrument. The implant includes a first deployment feature and a second deployment feature configured to engage with vertebrae. The instrument includes an inserter portion, a coupling member, a first actuator, and a second actuator. The inserter portion includes at a proximal end a receiving block, at a distal end a sleeve, and a channel extending therethrough. The coupling member includes at a proximal end movably coupled with the receiving block, a middle portion that slides within the channel, a distal end that couples the spinal implant, and a first axial bore extending therethrough. The first actuator includes a proximal end with a first projection for engaging the receiving block, a first shaft extending through the first axial bore, and a distal end with a first engagement feature for engaging a first deployment feature of the implant. The second actuator includes a proximal lend with a second projection for engaging the receiving block, a second shaft extending through a second axial bore of the first shaft, and a distal end with a second engagement feature for engaging a second deployment feature of the implant. 
         [0012]    In other features, the receiving block includes features for limiting rotational movement of at least one of the first actuator and the second actuator to limit actuation of at least one of the first deployment feature and the second deployment feature. In yet other features, the proximal end of the first actuator includes a receiving end with features for limiting rotational movement of at least one of the first actuator and the second actuator. In still yet other features, the instrument includes a release mechanism that forces the first actuator and the second actuator apart. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of an exemplary surgical instrument and implant according to the principles of the present disclosure and an implant. 
           [0014]      FIG. 2  is a partially exploded perspective view of the surgical instrument according to the principles of the present disclosure. 
           [0015]      FIG. 3  is an exploded perspective view of a housing and a first shaft of the surgical instrument according to the principles of the present disclosure. 
           [0016]      FIG. 4  is an exploded perspective view of a handle assembly and a second shaft of the surgical instrument according to the principles of the present disclosure. 
           [0017]      FIG. 5  is a top elevational view of a sleeve of the surgical instrument according to the principles of the present disclosure. 
           [0018]      FIGS. 6 and 7  are top and side elevational views of a clamping member of the surgical instrument according to the principles of the present disclosure. 
           [0019]      FIGS. 8-10  are partial perspective views of a distal end of the surgical instrument engaging and deploying features of the implant according to the principles of the present disclosure. 
           [0020]      FIG. 11  is a perspective view of a second exemplary instrument according to the principles of the present disclosure. 
           [0021]      FIG. 12  is a partially exploded perspective view of the second instrument according to the principles of the present disclosure. 
           [0022]      FIGS. 13-16  are perspective, top elevational, and side views of a receiving block of the second instrument according to the principles of the present disclosure. 
           [0023]      FIG. 17  is a perspective view of a proximal end of an outer shaft and handle assembly of the second instrument according to the principles of the present disclosure. 
           [0024]      FIG. 18  is a perspective view of a proximal end of an inner shaft and handle assembly of the second instrument according to the principles of the present disclosure. 
           [0025]      FIGS. 19 and 20  are perspective views of the second instrument illustrating actuation for deploying the deployment features of the implant. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Implants or vertebral body replacements may be placed in the interdiscal space between adjacent vertebrae of the spine. The implants may include one or more features that are deployed to affix the implants to the adjacent vertebrae. For example, a stand-alone interbody fixation system, as disclosed in commonly assigned U.S. continuation-in-part application Ser. No. 13/633,301 to Vishnubhotla et al. filed Oct. 2, 2012, which is a continuation-in-part of U.S. Pat. No. 8,328,870, to Patel et al., both of which are incorporated by reference in their entirety, provides a solid fixation in all aspects by using counter-rotating blades that provide fixation to the vertebrae. Such implants may be inserted, positioned, and deployed by various embodiments of the instrument of the present disclosure. As can be understood by one skilled in the art, these embodiments are shown for illustrative purposes and are not intended to limit the scope of the invention. 
         [0027]    Embodiments of the invention will now be described with reference to the Figures, wherein like numerals reflect like elements throughout. The terminology used in the description presented herein is not intended to be interpreted in any limited or restrictive way, simply because it is being utilized in conjunction with detailed description of certain specific embodiments of the invention. Furthermore, embodiments of the invention may include several novel features, no single one of which is solely responsible for its desirable attributes or which is essential to practicing the invention described herein. 
         [0028]    The words proximal and distal are applied herein to denote specific ends of components of the instrument described herein. A proximal end refers to the end of an instrument nearer to an operator of the instrument when the instrument is being used. A distal end refers to the end of the instrument further from the operator and extending towards the surgical area of a patient and/or the implant. 
         [0029]    Referring to  FIGS. 1 and 2 , a surgical instrument  100  according to the principles of the present disclosure is shown. The instrument  100  includes features to enable insertion of an implant  300  into the spinal area of a patient and to enable actuation of additional features of the implant  300  after insertion. The instrument includes a housing  102 , a handle assembly  104 , a sleeve  106 , a clamping member  108 , an outer shaft  110 , and an inner shaft  112 . The clamping member  108  includes features that enable coupling of the instrument  100  with the implant  300 . The sleeve  106  includes features that actuate the coupling member  108  to couple the implant  300 . When the implant  300  is coupled, the instrument  100  may be used to position the implant  300  in the spinal area of the patient. The outer shaft  110  and the inner shaft  112  include features that actuate the additional features of the implant  300 . For example, once the implant  300  has been positioned in the spinal area, the outer shaft  110  and the inner shaft  112  may be rotated to deploy features of the implant  300  that engage with vertebrae in the spinal area. 
         [0030]    Referring now to  FIG. 2 , a partial exploded view shows additional features of the instrument  100 . The housing  102  includes features for attachment of the sleeve  106 , the clamping member  108 , the outer shaft  110 , and the handle assembly  104 . The housing  102  includes a wheel  114  that freely rotates on the distal end of the housing  102  and includes features that engage with the sleeve  106 . For example, the wheel  114  may include a thread  116  on an inner surface of the wheel  114  that engages with a corresponding threaded portion  118  on the proximal end of the sleeve  106 . The housing  102  may include a threaded portion  120  at the proximal end for attachment of the handle assembly  104 . For example, the threaded portion  120  may engage with threads of a cap  122  on the handle assembly  104 . 
         [0031]    The sleeve  106  includes a channel  124  that extends the length of the sleeve  106  and is configured to receive the clamping member  108 . The channel  124  may be formed by boring a first series of windows  126  on a first side of the sleeve. The windows  126  may be cut into the sleeve  106  until a wall of material remains on a second side of the sleeve opposite the first side. After the first series of windows  126  has been cut, a second series of windows may be cut through the second side of the sleeve until cross members  128  of material remain on the first side of the sleeve. The second series of windows may be spaced to remove remaining material between the first series of windows  126 . The resulting channel  124  is configured to permit sliding engagement with the clamping member  108 . 
         [0032]    The sleeve  106  forms an opening  130  at the proximal end to permit passage of the clamping member  108  through the channel  124  into the housing  102 . The sleeve  106  forms a mouth  132  at the distal end that allows for sliding engagement with the clamping member  108 . The mouth  132  may include flared portions  134  that flare away from a center line of the instrument  100 . The flared portions  134  are configured to engage with the clamping member  108  and to couple the implant  300  to the instrument  100  as described below. 
         [0033]    Continuing with  FIG. 2 , the clamping member  108  includes an elongated portion  136  and a pair of arms  138 . The elongated portion  136  extends through the channel  124  to engage with the housing  102 . At the proximal end of the elongated portion  136 , a locking feature  140  is configured to fixedly attach the clamping member  108  to the housing  102 . For example the locking feature  140  may include a notch cut into the clamping member  108  that engages with a lock pin (not shown) inside the housing  102 . The elongated portion  136  may further include one or more holes  142  to facilitate cleaning of the instrument  100  and to reduce the weight. The pair of arms  138  extends from the distal end of the elongated portion  136  and terminates in a pair of tips  144 . The tips  144  may flare away from the center line of the instrument  100  similar to the flared portions  134  of the sleeve  106 . The tips  144  may include projections  146  that partially extend towards the center line of the instrument  100 . In other features, the projections  146  may partially extend towards the distal end of the instrument  100 . The clamping member  108  further includes a first axial bore  148  that extends the length of the elongated portion  136  to enable the outer shaft  110  to pass through the clamping member  108  as depicted in  FIGS. 8 and 9 . 
         [0034]    Once the sleeve  106  and clamping member  108  are coupled within the housing  102  and the wheel  114  on the housing is rotated, the threaded portion  118  of the sleeve  106  advances along the thread  116  of the wheel  114  causing the sleeve  106  to slide relative to the clamping member  108 . For example, rotating the wheel  114  in a first direction advances the sleeve  106  towards the distal end of the instrument  100  while rotating the wheel in a second direction retracts the sleeve  106  towards the proximal end of the instrument  100 . As the sleeve  106  advances towards the distal end of the instrument  100 , the flared portions  134  engage with the tips  144 . The flared portions  134  compress the tips  144  towards the center line of the instrument  100  causing the arms  138  to flex inwardly towards the center line. As shown in  FIG. 10 , the tips  144  are configured to engage with corresponding holes  302  on the implant  300 . As the tips  144  are compressed, the projections  146  provide a clamping force on the implant  300  to couple the implant  300  to the instrument  100 . 
         [0035]    Continuing with  FIG. 2 , the outer shaft  110  extends from the housing  102  through the first axial bore  148  in the clamping member  108 . The outer shaft  110  may freely rotate in the first axial bore  148  relative to the clamping member  108 . Referring to  FIGS. 2 and 3 , the proximal end of the outer shaft  110  may couple with a follower gear  150  inside the housing  102  and the distal end extends through the axial bore  148  and past the mouth  132  of the sleeve  106 . The distal end of the outer shaft  110  includes a first engagement feature  152  configured to actuate a first deployment feature, such as a first blade  304  of the implant  300  as depicted in  FIGS. 10-12 . For example, the first engagement feature  152  may include a hexagonal projection. The outer shaft  110  further includes a second axial bore  154  extending through the length of the outer shaft  110  from the proximal end to the distal end. 
         [0036]    Referring now to  FIGS. 2 and 4 , the inner shaft  112  extends from the handle assembly  104  through the second axial bore  154  in the outer shaft. The inner shaft  112  freely rotates in the second axial bore  154  relative to the outer shaft  110 . The proximal end of the inner shaft  112  may couple with a handle  156  and a distal end may extend past an opening  158  in the first axial bore  148 . The distal end of the inner shaft  112  includes a second engagement feature  160  configured to actuate a second deployment feature, such as a second blade  306  of the implant as depicted in  FIGS. 10-12 . For example, the second engagement feature  160  may include a splined projection. 
         [0037]    Referring now to  FIGS. 3 and 4 , exploded views of the handle assembly  104 , inner shaft  112 , housing  102 , and outer shaft  110  are shown in greater detail. The handle assembly  104  includes the cap  122 , the handle  156 , and a striking member  164 . The inner shaft  112  may pass though the cap  122  and the handle  156  to connect with the striking member  164  using a screw  166  or other fixation member. The cap  122  couples the handle assembly  104  to the housing  102  and allows rotation of the handle  156  and inner shaft  112 . When the operator applies torque to rotate the handle  156 , the inner shaft  112  rotates together and in the same direction as the handle  156 . In addition, the operator may apply a striking force to the striking member  164  to drive the implant  300  further into the spinal area. The striking member  164  transfers the striking force to the inner shaft  112 . 
         [0038]    A drive gear  167  and an alignment block  168  are disposed along the proximal end of the inner shaft  112 . The drive gear  167  may be fixedly attached to the inner shaft  112  to rotate with the inner shaft  112 . The alignment block  168  may be fixedly attached to or formed on the inner shaft  112  and positioned to align the inner shaft  112  and the outer shaft  110  during assembly of the instrument  100 . The alignment block  168  may include notches  170  to align the inner shaft  112  relative to the outer shaft  110  as described below. In addition, when the operator applies a striking force to the striking member  164 , the alignment block  168  may transfer the striking force to the follower gear  150  and the housing  102  rather than to the distal end of the inner shaft  112 . The housing  102  then transfers the striking force to the sleeve  106  to position the implant  300  deeper into the spinal area. This may prevent damage to the engagement features of the shafts. 
         [0039]    As depicted in  FIG. 3 , the housing  102  includes a gear set that transfers torque from the drive gear  167  to the outer shaft  110 . The gear set includes one or more transfer gears  172  configured to be driven by the drive gear  167  on the inner shaft  112 . The transfer gears  172  may be, for example, beveled gears. The transfer gears  172  may be rotatably fixed in removable sleeves  174  disposed in U-shaped channels  176  of the housing  102 . A clip  178  may lock the sleeves  174  into the U-shaped channels  176 . 
         [0040]    When the operator applies torque to the handle  156 , the drive gear  167  rotates in the same direction as the handle  156 . The inner shaft  112 , also attached to the handle  156 , rotates in the same direction. The drive gear  167  causes the transfer gears  172  to rotate and transfer torque to the follower gear  150  attached to the proximal end of the outer shaft  110 . The transfer gears  172  cause the follower gear  150  to rotate in the opposite direction as the drive gear  167 . Thus, the outer shaft  110 , which is attached to the follower gear  150 , rotates in the opposite direction as the inner shaft  112 . Thus, when the operator rotates the handle  156  in one direction, the inner shaft  112  and the outer shaft  110  counter-rotate. 
         [0041]    One or more anti-rotation pins  179  may be used attach the follower gear  150  and to prevent the inner shaft  112  and the outer shaft  110  from rotating beyond a predetermined angle. For example, the anti-rotation pins  179  may radially extend away from the center line of the instrument  100  in a cavity  180  of the housing  102 . The cavity  180  may prevent rotation of the pins  179  beyond the predetermined angle. For example, the anti-rotation pins  179  may prevent over-rotation of the first and second deployment features  304 ,  306  of the implant  300 . 
         [0042]    The transfer gears  172  may also include one or more alignment nibs  182  that extend from the center of the transfer gears  172  towards the inner shaft  112 . The alignment nibs  182  may be used in conjunction with the notches  170  of the alignment block  168  to align the inner shaft  112  with the outer shaft  110  during assembly. For example, the inner shaft  112  may not extend through the opening  158  unless the alignment nibs  182  are lined up with the notches  170 . When the alignment nibs  182  pass through the notches  170 , then the first and second engagement features  152  and  160  are properly aligned for engagement with corresponding features on the implant  300 . 
         [0043]    Referring now to  FIGS. 5-7  the sleeve  106  and clamping member  108  are shown in greater detail. The sleeve  106  may include a first set of guide pins  184  on an inner surface of the mouth  132 . The sleeve  106  may include a second set of guide pins  186  on an inner surface of the channel  124 . The guide pins  184 ,  186  slidably engage with a track  188  on the clamping member  108 . The guide pins  184 ,  186  prevent over-deflection of the arms  138  when the sleeve  106  advances towards the distal end of the clamping member  108 . Additional guide pins may be provided at other locations inside the channel  124  to engage with the track  188  and maintain structural integrity of the clamping member  108 . 
         [0044]    The clamping member  108  may include a positioning marker  190  on the tips  144  to aid in locating the position of the implant  300  relative to the spinal area under fluoroscopy. The positioning marker  190  may be a cutout or notch in a sidewall of the tips  144 . In additional features, the clamping member  108  may attach to the distal end of the housing  102  using the locking feature  140 . For example, the clamping member  108  may be inserted into a receptacle in the distal end of the housing  102  as seen in  FIG. 3 . The locking feature  140  may then engage with a lock pin  194  disposed in the housing  102 . The lock pin  194  may include a spring  196  to facilitate locking and release of the lock pin  194  from the locking feature  140 . 
         [0045]    Referring to  FIGS. 8-10 , the instrument  100  may be used to couple the implant  300  to the distal end of the instrument  100  and actuate features of the implant  300 . In  FIG. 8 , the distal ends of the first shaft  110  and the second shaft  112  project from the axial bore  148  in the clamping member  108  so that the first and second engagement features  152  and  160  may engage with corresponding features of the implant  300 . The sleeve  106  is retracted so that the flared portions  134  do not compress the tips  144  of the clamping member  108 . Thus, the projections  146  on the tips  144  may engage with the holes  302  in the implant  300 . In  FIG. 9 , the projections  146  are engaged with the implant  300  and the sleeve  106  may be advanced towards the distal end of the instrument  100  using the wheel  114 . The coupling member  108  holds the implant  300  to the outer shaft  110  and the inner shaft  112 , enabling the first and second engagement features  152  and  160  to engage with corresponding receptacles in the implant  300 . In  FIG. 10 , the operator applies torque to rotate the handle  156  which causes the inner shaft  112  to rotate and actuate the first deployment feature  304  of the implant. The gear set coupling the inner shaft  112  and the outer shaft  110  transfers torque from the inner shaft  112  to the outer shaft  110 . The outer shaft  110  thus rotates in the opposite direction to actuate the second deployment feature  306  of the implant  300 . 
         [0046]    Referring now to  FIG. 11 , another exemplary surgical instrument  200  includes features to enable insertion of the implant  300  into the spinal area of a patient and to enable actuation of the deployment features of the implant  300  after insertion. The instrument  200  shares similar features as the first exemplary instrument  100  such as housing  102 , handle  104 , sleeve  106 , and clamping member  108  as well as the counter-rotating outer shaft  110  and inner shaft  112 . Therefore, similar numerals are used with reference to similar features. For example, the instrument  200  includes a housing  202 , handle assemblies  204   a  and  204   b  (collectively handle assemblies  204 ), a sleeve  206 , a clamping member  208 , an outer shaft  210 , and an inner shaft  212 . 
         [0047]    The instrument  200  includes features that enable coupling of with the implant  300  in a similar fashion as instrument  100 . For example, the instrument  200  includes a positioning wheel  214  similar to the wheel  114 . However, the sleeve  206  may not move in the present exemplary instrument  200  but may be rigidly secured to the housing  202 . For example, the positioning wheel  214  may act on a proximal threaded end (not shown) of the clamping member  208  extending through the housing  202  in order to position the clamping member  208  within the attached sleeve  206 . The sleeve  206  includes features that force portions of the clamping member  208  together to clamp the implant  300  similar to the sleeve  106 . When the implant  300  is coupled to the clamping member  208 , the instrument  200  may be used to position the implant  300  in the spinal area of the patient similar to instrument  100 . 
         [0048]    The outer shaft  210  and the inner shaft  212  include features that actuate the blades  304  and  306  of the implant  300 . For example, once the implant  300  has been positioned in the spinal area, the outer shaft  210  and the inner shaft  212  may be rotated to deploy features of the implant  300  that engage with vertebrae in the spinal area. The distal ends of the shafts  210  and  212  may include various driving features including hexalobe, star-shaped, Allen-wrench, spline drives or any other suitable pattern that mates with features of the implant  300 . In some examples, the distal ends of the shafts  210  and  212  may include one or more detachable tips such as inner shaft tip  260  and outer shaft tip  252  respectively as shown in  FIG. 12 . The detachable tips may deform under a predetermined amount of torque to prevent over deployment or rotation of the blades  304  or  306 . The detachable tips may include various sizes for various sizes of implants  300 . The detachable tips may be disposable or reusable. 
         [0049]    Continuing now to  FIG. 12 , a partial exploded view shows additional features of the instrument  200 . The housing  202  may include features for attachment of the sleeve  206  and/or the clamping member  208 . In some examples, the sleeve  206  may be integral with the housing  202 . The outer shaft  210  and the inner shaft  212  may pass through the housing  202  similar to the shafts  110  and  112  and housing  102 . For example, the outer shaft  210  may include an outer diameter smaller than the diameter of a cannula or channel extending through the housing  202 . The outer shaft  210  may include an axial bore similar to the axial bore  154  of instrument  100 . The inner shaft  212  may be inserted through the axial bore of the outer shaft  210  and rotate freely therein. 
         [0050]    The housing  202  may include the positioning wheel  214  on a proximal end which freely rotates and includes features that engage the proximal end of the clamping member  208  to position the clamping member  208  within the sleeve  206 . For example, an inner surface of the wheel  214  may include a thread (not shown) that engages with a corresponding threaded portion (not shown) on the proximal end of the clamping member  208  similar to the thread  118  on the proximal end of the sleeve  106  of the instrument  100 . Rotation of the wheel  214  may position the clamping member  208  relative to the sleeve  206 . For example, as the wheel  214  rotates in one direction, the inner thread of the wheel  214  engages more of the threaded portion on the clamping member  208  and pulls the clamping member  208  proximally into the sleeve  206  to clamp the implant  300 . Various features may be used to pull the clamping member  208  into the sleeve  206  to retain the implant  300  as described above with reference to the instrument  100 . Rotation of the wheel  214  in the opposite direction positions the clamping member  208  distally to release the implant  300 . 
         [0051]    The proximal end of the housing  202  may include or couple with a receiving block  215  that receives the outer shaft  210 . The receiving block  215  may include a generally cylindrical, cannulated shape from its proximal end to its distal end. Referring now also to  FIGS. 13-16 , the outer shaft  210  may be inserted through an aperture, channel, or cannula  217  in the block  215  extending from a proximal end to a distal end. The distal end may couple with the housing  202  through various means including welding, threaded connection, pins, etc. either removably or permanently. The receiving block  215  may include markings  219   a  and  219   b  (collectively markings  219 ) on a proximal surface  221  that assist with aligning the handle assemblies  204  during a deployment procedure. 
         [0052]    The receiving block  215  may include various features that act on the handle assemblies  204  to align and/or limit rotation of the outer shaft  210  and the inner shaft  212 . These features may control a deployment angle between the concentric shafts as described herein. Thus, actuation of the deployment features  304  and  306  of the implant  300  may be limited to prevent over-rotation. Further, full actuation of the deployment features  304  and  306  may correspond to tactile feedback provided by the features. For example, the receiving block  215  may include a plurality of features such as markings, slots, ramps, and tabs that aid with alignment of the handle assemblies  204  and engage features of the handle assemblies  204  to guide and limit rotation of the shafts  210  and  212  as described below. The plurality of features above may be repeated along the circumference of the receiving block  215 . For example, the features may be repeated 180 degrees apart from one another. 
         [0053]    For purposes of illustration, most features will be primarily discussed with reference to a first set of the features denoted with numerals ending in suffix “a.” A second set of the features, each of which may be repeated 180 degrees from the first set of features about the circumference of the receiving bock  215 , will be denoted with numerals ending in suffix “b.” Features of the receiving block  215  may include the markings  219 , the first surface  221 , initial slots  223 , an outer surface  225 , first ledges  227 , deployed slots  229 , ramped portions  231 , second ledges  233 , and stops  235 . 
         [0054]    A first marking  219   a  may indicate a desired initial position of the first handle assembly  204   a  prior to deployment of the implant  300 . A second marking  219   b  may indicate an initial position of the second handle  204   b  prior to deployment of the implant  300 . The first marking  219   a  may be diametrically opposed 180 degrees from the second marking  219   b . Either of the handle assemblies  204   a  and  204   b  may initially be aligned with either of the markings  219   a  and  219   b . For example, the first handle assembly  204   a  may initially align with the first marking  219   a  or the second marking  219   b . Likewise, the second handle assembly  204   b  may initially align with the first marking  219   a  or the second marking  219   b . For purposes of clarity, the instrument  200  will be described with the first handle assembly  204   a  initially aligned with the first marking  219   a  and the second handle assembly  204   b  initially aligned with the second marking  219   b.    
         [0055]    Each of the markings  219  may be radially aligned with first and second initial slots  223   a  and  223   b  (collectively initial slots  223 ) on a proximal portion of the receiving block  215  that engage features of at least one of the handle assemblies  204 . The initial slots  223  may include a depth extending radially inward from the outer surface  225  for receiving retractable portions of the handle assemblies  204 . The initial slots  223  may include a length extending axially parallel along the outer surface  225 . The initial slots  223  may include a width extending along a portion of the circumference of the outer surface  225 . 
         [0056]    For example, first initial slot  223   a  may extend from the proximal surface  221  distally a first length L1 along the outer surface  225  of the receiving block  215 . First initial slot  223   a  may terminate at the first ledge  227   a  which extends circumferentially around at least a portion of the outer surface  225  of the receiving block  215 . The first handle assembly  204   a  includes features that engage the first initial slot  223   a . The first handle assembly  204   a  may engage the first initial slot  223   a  when the instrument  200  is in a non-deployed configuration or an initial configuration prior to deploying the blades  304  and  306  of the instrument as illustrated in  FIG. 19 . The initial slots  223  limit rotation of the first handle assembly  204   a  in a first direction, such as a clockwise direction as described below. 
         [0057]    The receiving block  215  further includes first and second deployed slots  229   a  and  229   b  (collectively deployed slots  229 ) that engage features of at least one of the handle assemblies  204 . The deployed slots  229  may include depth, width, and length similar to the initial slots  223 . For example, first deployed slot  229   a  may extend from the proximal surface  221  distally the first length L1 along the outer surface  225  of the receiving block  215 . First deployed slot  229   a  may terminate at the first ledge  227 . The first handle assembly  204   a  includes features that engage the first deployed slot  229   a . The first handle assembly  204   a  may engage the first deployed slots  229   a  when the instrument  200  is in a deployed configuration or a final configuration after deploying the blades  304  and  306  of the implant  300  as illustrated in  FIG. 20 . The deployed slots  229  limit rotation of the first handle assembly  204   a  in a second direction, such as a counter-clockwise direction as described below. 
         [0058]    The slots  223  and  229  may be disposed along the circumference of the receiving block  215  at various angles to control an amount of deployment of at least one of the blades  304  and  306  of the implant  300 . The initial slots  223 , the first ledge  227 , and the deployed slots  229  may engage portions of the first handle assembly  204   a  to limit rotation of the handle assembly  204   a . For example, initial slot  223   a  may be separated from a corresponding deployed slot  229   a  by an angle A correlated to the amount of rotation required to deploy a first blade  304 . The outer surface  225  may further include radially ramped portions  231  extending from each initial slot  223  to each corresponding deployed slot  229 . The radially ramped portions  231  include an increasing radius. For example, ramped portion  231   a  may include a first radius R1 of outer surface  225  corresponding to a depth of the initial slot  223   a  and increase to a second radius R2 just before the deployed slot  229   a  as shown in  FIGS. 13 and 14 . The ramped portions  231  provide increasing resistance on a feature of the first handle assembly  204   a  as it rotates from the initial slot  223  to the deployed slot  229 . The increasing resistance may provide tactile feedback to the user. The increasing radius may cause a feature of the first handle assembly  204   a  to snap into the deployed slot  229   a  providing audible feedback. 
         [0059]    The receiving block  215  includes additional features that may engage with the second handle assembly  204   b . The receiving block  215  may include a second ledge  233  and first and second stops  235   a  and  235   b  (collectively stops  235 ). For example, the second ledge  233  may be proximally disposed from the first ledge  226  a distance L2 and engage with features of the second handle assembly  204   b  to limit distal travel of the inner shaft  206 . The stops  235  may be disposed along the second ledge  233  and limit rotation of the second handle assembly  204   b . The second handle assembly  204   b  includes features that engage the second stop  235   b . The second handle assembly  204   b  may engage the second stop  235   b  when the instrument  200  is in a deployed configuration or a final configuration after deploying the blades  304  and  306  of the implant  300  as illustrated in  FIG. 20 . The stops  235  limit rotation of the second handle assembly  204   b  in a first direction, such as a clockwise direction as described below. 
         [0060]    Referring now to  FIGS. 17 and 18 , the first and second handle assemblies  204   a  and  204   b  include similar features such as first and second handles  256   a/b  (collectively handles  256 ), triggers  257   a/b  (collectively triggers  257 ), and housings  259   a/b  (collectively housings  259 ) that engage various features of the handle assemblies  204  and the receiving block  215 . The handles  256  may include a gripping surface such as a silicone wrap or other textured surface to enhance the user&#39;s grip on the instrument  200 . The housings  259  may house the triggers  257 , each of which may include first and second projections  261   a/b  (collectively projections  261 ) extending outside the housings  259 . The triggers  257  may be biased by one or more bias mechanisms such as a spring to extend the projections  261  away from proximal ends of the housings  259 . 
         [0061]    In  FIG. 17 , the first handle assembly  204   a  includes first trigger  257   a  with first projection  261   a  extending away from first housing  259   a  for engaging initial slots  223 , first ledge  227 , ramped portions  231 , and deployed slots  229 . The first housing  259   a  may be rigidly coupled with a receiving end  263  of the outer shaft  210  and extend radially way from the outer shaft  210 . The receiving end  263  includes an aperture  265  through which the inner shaft  210  may be inserted. The receiving end  263  may include a circular outer profile with one or more notches and pathways about the perimeter for receiving features of the second handle assembly  204   b.    
         [0062]    For example, a first notch  267  may be disposed at a point along the circumference of the receiving end  263  that is diametrically opposite of point of attachment of the first housing  259   a . When the first handle assembly  204   a  is inserted into the receiving block  215  and aligned with the first marking  219   a , the first notch  267  may be aligned with the second marking  219   b . The first notch  267  may extend from a proximal side of the receiving end  263  to a distal side that engages the proximal surface of the receiving block  215 . For example, the first notch  265  may extend a length L3. A second notch  269  may be disposed at a point along the circumference of the receiving end  263  that is proximate to the point of attachment of the first housing  259   a . For example, the second notch  269  may be disposed at some angle relative to the first housing  259   a  and/or the first notch  267 . The first and second notches  267  and  269  may also extend the length L3. A radially ramped portion  271  may extend between the first notch  267  and the second notch  269  similar to the increasing radius of radially ramped portion  231  of the receiving block  215  to provide tactile and audible feedback similar to the slots  223  and  229  above. 
         [0063]    In  FIG. 18 , the second handle assembly  204   b  includes second trigger  257   b  with second projection  261   b  extending away from the second housing  259   b  for engaging the first notch  267 , second notch  269 , and radially ramped portion  271 . The second housing  259   b  may be coupled with a top portion  273  of the inner shaft  212 . A release mechanism  275  may be pivotally coupled to the top portion  273 . The release mechanism  275  may include a lever arm  277  with a cam portion  279  that engages the receiving end  263  of the outer shaft  210 . As the lever arm  277  rotates, the cam portion  279  forces the top portion  273  of the inner shaft  212  away from the receiving end  263  of the outer shaft  210  to separate the surfaces therebetween. 
         [0064]      FIGS. 19 and 20  illustrate actuation of the instrument  200  for deploying features of the implant  300 . Initially, the first handle assembly  204   a  and second handle assembly  204   b  may be diametrically opposed 180 degrees to form a generally T-shaped configuration in an initial position. The first projection  261   a  of the first handle assembly  204   a  may be aligned with the first initial slot  223   a . The second projection  261   b  of the second handle assembly  204   b  may be aligned with the first notch  267  of the receiving end  263  of the outer shaft  210 . The user may apply torque to the handles  256   a  and  256   b  causing the inner and outer shafts  210  and  212  to counter-rotate about their common axis. As the handle assemblies  204  rotate towards one another, the first projection  261   a  may engage along the ramped portion  231  of the receiving block  215  and the second projection  261   b  may engage along the ramped portion  271  of the receiving end  263  of the outer shaft  210 . 
         [0065]    When the handle assemblies  204  are fully rotated, the instrument may form a more generally V-shaped appearance viewed from the proximal end in a final position. Upon full deployment of the features of the implant  300 , the first projection  261   a  may engage the first deployed slot  229   a . The second projection  261   b  may engage the stop  235  of the receiving block as well as the second notch  269 . The projections  261  may snap into place due to force applied by a bias member. Thus, the instrument  200  may provide tactile and audible feedback when full deployment of the features of the implant are complete. Upon deployment, the instrument  200  may be removed by actuating the release mechanism  275  to pry apart the second handle assembly  204   b  from the first handle assembly  204   a  and thus, to separate the inner shaft  212  from the implant  300 . The outer shaft  210  may subsequently be removed from the implant  300 . 
         [0066]    Although the instrument  200  is described with reference to the sleeve  206 , clamping member  208 , and alignment block  215 , the features of the implant  300  may be deployed using only the handle assemblies  204  and their respective shafts  210  and  212 . For example, the implant  300  may be inserted into the disc space between adjacent vertebrae using any of a variety of instruments. Once within the disc space, the additional diameter of the sleeve  206  may create difficulty in maneuvering the instrument  200  within the patient, especially in lower regions of the spine near the pelvic bone. The shafts  210  and  212  may be inserted directly into the implant  300  to deploy the blades  304  and  306 . Surfaces of the handles  204   a  and  204   b  may prevent some over deployment. However, ideally, the full system including the alignment block  215  would be used to prevent uniform deployment of the blades  304  and  306 . 
         [0067]    Example embodiments of the methods and components of the present invention have been described herein. As noted elsewhere, these example embodiments have been described for illustrative purposes only, and are not limiting. Other embodiments are possible and are covered by the invention. Such embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.