Abstract:
A method and apparatus assisting safe one-handed insertion of an implant. An implant implantation device has a frame which includes a trigger mechanism, an outer sleeve mechanically coupled to the frame, an inner shaft having a grabber for mechanically engaging an implant, the inner shaft slidably disposed within the outer sleeve, and a retaining element disposed over the inner shaft for directing the grabber toward a closed position. An implant clip has a first member, a second member pivotally coupled to the first member, a first implant holder pivotally coupled to the first member, the coupling causing the implant clip to have a closed position and an open position, and a second implant holder, the second implant holder pivotally coupled to the second member, a surface of the first implant holder and a surface of the second implant holder remaining substantially parallel to each other while the first member and the second member pivot between the closed position and the open position.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Spinal surgery involves many challenges as the long-term health and mobility of the patient often depends on the surgeon&#39;s technique and precision. One type of spinal surgery involves the removal of a damaged disc that is located between adjacent vertebral bodies. Procedures are known in which the damaged disc is replaced with an artificial disc or spinal fusion cage.  
         [0002]     The artificial disc or spinal fusion cage includes protrusions for engaging the adjacent vertebral bodies to aid in the initial fixation of the artificial disc or spinal fusion cage. These protrusions are often sharp and can injure the surgeon&#39;s hand, if contacted, during implantation.  
         [0003]     The insertion of an article, such as the artificial disc or fusion cage, presents the surgeon with several challenges. The adjacent vertebral bodies collapse upon each other once the damaged disc is removed. These bodies must be separated to an extent sufficient to enable the placement of the prosthesis. However, if the vertebral bodies are separated, or distracted, to beyond a certain degree, further injury to the patient can occur. The artificial disc should also be properly positioned between the adjacent vertebral bodies. Over-insertion posteriorly, or under-insertion anteriorly of the prosthesis can lead to pain, postural problems and/or limited mobility or freedom of movement.  
         [0004]     Specialized tools have been developed to facilitate the placement of devices, such as artificial discs, between adjacent vertebral bodies of a patient&#39;s spine. Among the known tools for performing such procedures are spinal distractors and insertion devices. However, use of these tools to distract the vertebral bodies and insert the artificial disc or spinal fusion cage can prove cumbersome.  
         [0005]     Exemplary devices for installing prostheses and/or grafts between vertebral bodies are disclosed in U.S. Pat. Nos. 5,431,658 and 5,505,732. U.S. Pat. No. 5,431,658 discloses a facilitator device for the insertion of bone grafts between two adjacent vertebrae. The disclosed tool has two flat, tong-like guides that distract the vertebrae as a screw-type inserter forces the graft between the distracted vertebrae. U.S. Pat. No. 5,505,732 discloses an apparatus and a method of inserting implants. The intervertebral space is first distracted and a hollow sleeve having teeth at one end is then driven into the vertebrae that are adjacent the disc space. A drill is then passed through the hollow sleeve, removing the disc and the bone in preparation for receiving the implant, which is then inserted through the sleeve. These devices are both operated with two-hands and do not provide safety features for preventing injury to a surgeon.  
         [0006]     Despite existing tools and technologies, there remains a need for an improved device to facilitate insertion of an artificial disc or a spinal fusion cage.  
       SUMMARY OF THE INVENTION  
       [0007]     The invention is generally related to a method and apparatus for assisting in a safe one-handed insertion of an implant. An implant implantation device including (i) a frame which includes a trigger mechanism, (ii) an outer sleeve mechanically coupled to the frame, (iii) an inner shaft having a grabber for mechanically engaging an implant, the inner shaft slidably disposed within the outer sleeve and (iv) a retaining element for directing the grabber toward a closed position. The grabber can be removably coupled to the inner shaft. The retaining element can be a spring.  
         [0008]     Optional elements can include a knob, a drag adjustment screw, at least one protrusion, and a depth control member. The knob can be mechanically coupled to the outer sleeve for causing the outer sleeve and the inner shaft to be rotated about the frame. The drag adjustment screw can provide tension between the trigger mechanism and the inner shaft. The at least one protrusion can be located on the outer sleeve for slidably engaging a distraction instrument. The depth control member can be slidably coupled to the outer sleeve for providing a predetermined insertion depth of the implant.  
         [0009]     The grabber is provided to hold the implant during insertion of the implant between the vertebrae. The grabber includes grabber tips for mechanically engaging the implant. The grabber tips can have a variety of shapes. For example, the grabber tips can be dovetailed in shape or can include a first pair of slots for engaging a first tab of the implant and a second pair of slots for engaging a second tab of the implant. The first pair of slots can be different in size from the second pair of slots. A sizing slot can be located between the first pair of slots and second pair of slots to allow for a variation of tab and grabber slot dimensional differences.  
         [0010]     The grabber also can include at least one marking to identify a position of the implant in relationship to the patient. The marking can be a pin located on a surface of the grabber. The marking can be a plurality of machined slots on a surface of the grabber.  
         [0011]     There is also provided an implant clip for aligning an implant endplate radially, providing a lordotic angle for implantation, packaging the implant, holding the implant during the implant sterilization process, and protecting the surgeon from being cut by protrusions on a surface of the implant. The implant clip, includes (i) a first member; (ii) a second member pivotally coupled to each other, the coupling causing the implant clip to have a closed position and an open position, (iii) a first implant holder pivotally coupled to the first member, and (iv) a second implant holder, the second implant holder pivotally coupled to the second member, a surface of the first implant holder and a surface of the second implant holder remaining substantially parallel to each other while the first member and the second member pivot between the closed position and the open position. The first member and the second member can be shells. The implant clip can also include a spring for directing the implant clip toward a closed position.  
         [0012]     Each holder can define a depression, where each depression is angled with respect to its holder. Each depression can also be made from a conformable material. The second holder can include a pair of pins that slidably engage a respective pair of cylindrical cavities in the first holder, thereby causing the surface of each holder to remain substantially parallel to each other while the first member and the second member pivot between the closed position and the open position. Alternatively, the first holder and the second holder can include a respective pin and a respective cylindrical cavity that slidably engage each other, thereby causing the surface of each holder to remain substantially parallel to each other while the first member and the second member pivot between the closed position and the open position. Each holder can also include at least one alignment protrusion for aligning of an implantation instrument with the implant clip.  
         [0013]     A method of inserting the implant into an intervertebral space includes (i) loading an implant in an implant clip, (ii) mechanically engaging an implantation instrument to the implant and (iii) removing the implant from the implant clip. The implant can be an artificial disc or spinal fusion cage.  
         [0014]     Loading an implant in an implant clip includes (i) opening the implant clip, (ii) inserting the implant into the implant clip, and (iii) closing the implant clip.  
         [0015]     Mechanically engaging the implantation instrument to the implant includes (i) opening a grabber located on an end of the implantation instrument, (ii) aligning the grabber with the implant, and (iii) closing the grabber to mechanically engage the grabber to the implant.  
         [0016]     The method further includes (iv) distracting a prepared disc space with a distraction instrument, (v) inserting the implant into the prepared disc space with the implantation instrument, (vi) releasing the implant from the implantation instrument, and (vii) removing the implantation instrument and distraction instrument.  
         [0017]     Inserting the implant into the prepared disc space includes aligning the implantation instrument with the distraction instrument.  
         [0018]     The invention has many advantages. For example, the invention provides safe one-handed insertion of an implant into a prepared disc space. The invention reduces the amount of time required to complete the surgical procedure. The invention also provides for various manipulations of the implant without physically contacting the implant. For example, the invention can align an endplate of the implant radially and provide a lordotic angle for implantation, the invention can be used for packaging the implant, and the invention can be used to hold the implant during the implant sterilization process. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIG. 1A  shows a cross-sectional view of an insertion instrument of the present invention.  
         [0020]      FIG. 1B  shows a plan view of the insertion instrument of  FIG. 1A .  
         [0021]      FIG. 2A  shows a perspective view of one embodiment of a grabber of the present invention.  
         [0022]      FIG. 2B  shows a perspective view of another embodiment of a grabber of the present invention.  
         [0023]      FIG. 2C  shows a perspective view of yet another embodiment of a grabber of the present invention.  
         [0024]      FIG. 3A  shows a perspective view of one embodiment of an implant clip of the present invention.  
         [0025]      FIG. 3B  shows a side view of the implant clip of  FIG. 3A .  
         [0026]      FIG. 3C  shows a perspective view of another embodiment of an implant clip the of present invention.  
         [0027]      FIG. 3D  shows a side view of the implant clip of  FIG. 3B  in an open position.  
         [0028]      FIG. 3E  shows a perspective view of a shell of the implant clip of  FIG. 3A .  
         [0029]      FIG. 3F  shows a perspective view of a grabber aligned with a pair of implant holders.  
         [0030]      FIG. 3G  shows a perspective view of a pair of implant holders of the implant clip of  FIG. 3C .  
         [0031]      FIG. 3H  shows a cutaway perspective view of a pair of implant holders of the implant clip of  FIG. 3A .  
         [0032]      FIG. 31  shows a perspective view of the implant clip of  FIG. 3B  attached to the grabber of  FIG. 2C .  
         [0033]      FIG. 4  shows a perspective view of an artificial disc.  
         [0034]      FIG. 5  shows a perspective view of the insertion instrument of  FIG. 1  engaged to an implant enclosed in the implant clip of  FIG. 3A .  
         [0035]      FIG. 6A  shows perspective view of the artificial disc of  FIG. 4  engaged to the grabber of  FIGS. 2A .  
         [0036]      FIG. 6B  shows perspective view of another type of implant engaged to the grabber of  FIGS. 2B and 2C .  
         [0037]      FIG. 7  shows a perspective view of the artificial disc of  FIG. 4  being inserted into a prepared disc space using the insertion instrument if  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0038]     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The same number appearing in different drawings represents the same item. The drawings are not necessarily to scale, with emphasis instead being placed upon illustrating the principles of the invention.  
         [0039]     In general, the present invention is related to apparatus and method for safely inserting an implant into a prepared disc space. The implant can be an artificial disc or spinal fusion cage. Referring to  FIGS. 1A and 1B , insertion instrument  100  is shown in a side cross-sectional view and a plan view, respectively. Insertion instrument  100  includes frame or driver body assembly  110 , actuator assembly  126  and grabber  160  ( FIG. 2A-2C ). Insertion instrument  100  is a normally closed device, that is, grabber  160  is normally substantially contained within actuator assembly  126 .  
         [0040]     Actuator assembly  126  includes outer sleeve  130 , inner shaft  140 , and retaining pin  148 . Outer sleeve  130  includes a tapered end  175  which slidably engages tapers  163  on grabber  160  ( FIG. 2A-2C ), allowing for compression and expansion of the grabber  160  when in use. Inner shaft  140  includes female threaded end  142  and male threaded end  144 . Female threaded end  142  mates with spring retaining screw  152  and male threaded end  144  mates with grabber  160 . Internal compression spring  150  is fastened to actuator assembly  126  and held in place by spring retaining screw  152 . Once actuator assembly  126  is assembled, it is inserted into driver body assembly  110  and retained within assembly  110  with retaining pin  148 . Optional knob  170  can be mechanically attached to outer sleeve  130  to allow outer sleeve  130  and inner shaft  140  to rotate about driver body assembly  110 . Optional guides  171  can be attached to outer sleeve  130  to slidably mate with spinal disc distraction instrument  950  ( FIG. 7 ). Depth control member  173  can also be fixedly or slidably attached on outer sleeve  130  for providing a predetermined insertion depth of the implant.  
         [0041]     Driver body assembly  110  includes handle  112 , handle transition  114 , strike boss  116 , trigger mechanism  120 , and pivot pin  122 . Trigger mechanism  120  can be any type of trigger mechanism known in the art. Trigger mechanism  120  pivots about pivot pin  122  in driver body assembly  110 . When trigger mechanism  120  is “squeezed” toward handle  112 , grabber  160  ( FIG. 2A-2C ) extends from actuator assembly  126  and expands to release or attach to an implant. When trigger mechanism  120  is released, grabber  160  recedes into actuator assembly  126  and compresses, thereby engaging the implant or returning to its normally closed position. Optional drag adjustment screw  124  is rotatably coupled to driver body assembly  110  for adjusting the drag force between trigger mechanism  120  and spring retaining screw  152  of actuator assembly  126 .  
         [0042]      FIGS. 2A-2C  show various grabbers  160  of the present invention. Each grabber  160  includes grabber tips  162  for mechanically engaging the implant. Grabber tips  162  may be various shapes and sizes depending upon implant selection. As shown, grabber tips  162  may be slot shaped  162   a ,  162   b  or dovetailed shaped  162   c ,  162   d . Grabber tips  162  can engage implants having multiple heights. It should be understood grabber tips  162  can be any shape which can engage any type of implant. In an alternative embodiment, inner shaft  140  and grabber  160  can be one embodiment.  
         [0043]     Each grabber  160  includes female threaded hole  161  for mating to male threaded end  144  of inner shaft  140  of actuator assembly  126 . It should be understood that any means known in the art can be used to attach grabber  160  to inner shaft  140 .  
         [0044]     Each grabber  160  includes tapers  163  and relatively long expansion/compression slot  164  to allow grabber  160  to expand and compress during use.  FIGS. 2A-2C  show grabber  160  in the expanded position. Each grabber  160  also includes sizing slot  166  to allow for a variation of tab and grabber slot dimensional differences. Expansion/compression slot  169  ( FIG. 2B ) is an alternative embodiment of sizing slot  166 .  
         [0045]     Cephalad markers  168  can be included on a surface of grabber  160  to allow the user to determine the position of the implant. Markers  168  can be pin  168   a  or machined slots  168   b.    
         [0046]      FIGS. 3A-3I  show details of implant clip  300 . Implant clip  300  can be used to align the implant radially and provide a lordotic angle for implantation, can be used for implant packaging, can be used to hold the implant during the implant sterilization process, and can protect the surgeon from being cut by protrusions on the surface of the implant. Implant clip  300  includes a pair of symmetrical shells  306 ,  308 , superior implant holder  312 , inferior implant holder  318 , and spring  302 . In another embodiment, shells  306 ,  308  can be any type of member which can hold the implant.  
         [0047]     Each shell  306 ,  308  includes spring holder  301 , pivot member  310 , pivot hole  311 , and a pair of holder holes  314 . Each pivot member  310  snappingly and pivotally engages pivot hole  311  of opposing shells  306 ,  308 . Spring  302  is connected between shells  306 ,  308  and maintained in place by spring holders  301 . Spring  302  maintains implant clip  300  in a normally closed position, as shown in at least  FIGS. 3A and 3B .  
         [0048]     In one embodiment, as shown in  FIGS. 3A, 3D ,  3 F, and  3 H, superior implant holder  312  includes a pair of alignment protrusions  316 , a pair of protrusion members  317 , a pair of position poles  324 , and implant depression  315 . Inferior implant holder  318  includes a pair of alignment protrusions  322 , a pair of protrusion members  317 , a pair of position holes  326 , and implant depression  321 . In another embodiment, as shown in  FIGS. 3C and 3G , superior implant holder  312  and inferior implant holder  318  can be symmetrical for ease of production.  
         [0049]     Position poles  324  slidably engage position holes  326  such that surfaces  327 ,  329  remain substantially parallel to each other while implant clip  300  moves between a closed position as shown in  FIGS. 3A-3C  and an open position as shown in  FIG. 3D . It should be understood that any method can be employed to maintain holders  312 ,  318  parallel to each other. Once each holder  312 ,  318  is slidably engaged to each other, protrusion member  317  of each holder  312 ,  318  snappingly and pivotally engages a pair of holder holes  314  in respective shells  306 ,  308 . Shells  306 ,  308  can be made from a nylon-based plastic or other material known in the art which allows shells  306 ,  308  to be snappingly engaged to each other. Holders  312 ,  318  are typically made from injection moldable, gamma sterilizable hard plastics, such as Radel, Carbon Fiber, Peek, and Acrylonitrile Butadiene Styrene (ABS). However, holders  312 ,  318  can be made from any material known in the art which can protect the implant from damage.  
         [0050]     Implant depressions  315 ,  321  are made to accept a plurality of implants of different shapes and sizes. Implant depressions  315 ,  321  can be angled with respect to holders  312 ,  318  to provide a lordotic angle for the implant. Implant depressions  315 ,  321  can also be conformable to accept a plurality of implants. Alternatively, implant depressions  315 ,  321  can be rigid to accept individual respective implants.  
         [0051]     Alignment protrusions  316 ,  322  of implant clip  300  cause proper alignment of grabber  160  ( FIGS. 2A-2C ) with engagement protrusions  712 ,  722  of artificial disc  330  ( FIG. 4 ). Alignment protrusions  316 ,  322  can form alignment slot  323  as shown in at least  FIG. 3A  or an alignment window  325  as shown in  FIGS. 3C and 3G .  
         [0052]      FIG. 31  shows a perspective view of the implant clip of  FIG. 3B  attached to the grabber of  FIG. 2C . Grabber  160  is in a closed position (i.e., trigger released) within outer sleeve  130  of insertion instrument  100 . Grabber tips  162   c  are shown engaged to engagement indents  906  on artificial disc  900  which is contained within holders  312 ,  318  of implant clip  300 .  
         [0053]     The operation of insertion instrument  100  and implant clip  300  will be explained with reference to the figures. Although reference is made to an artificial disc  330 , its principles are applicable to spinal fusion cages.  
         [0054]     In operation, a user opens ( FIG. 3C ) implant clip  300  by depressing and holding opposite portions of shells  306 ,  308  at opposite ends of spring  302  ( FIG. 3B ) to an open position as shown in  FIG. 3D . Opened clip  300  is placed over a selected artificial disc  330 , causing implant holders  312 ,  318  to engage artificial disc  330  when shells  306 ,  308  are released.  
         [0055]     In one embodiment, the user aligns grabber  160  ( FIG. 2A ) of implantation instrument  100  with alignment slot  323  on implant clip  300 . Once aligned, the user squeezes trigger mechanism  120  ( FIG. 1 ) on implantation instrument  100 , thereby causing grabber tips  162   a ,  162   b  to be inserted over engagement tabs  712 ,  722  on artificial disc  330  ( FIG. 4 ). Once grabber tips  162  are inserted over engagement tabs  712 ,  722 , the user releases trigger mechanism  120 , causing grabber tips  162  to engage engagement tabs  712 ,  722  on artificial disc  330  as shown in  FIG. 5 . The user removes implant clip  300  from artificial disc  330  by opening and removing implant clip  300  from the now engaged artificial disc  330 , as shown in  FIG. 6A .  
         [0056]     In another embodiment, the user aligns grabber  160  ( FIGS. 2B and 2C ) of implantation instrument  100  with alignment window  325  on implant clip  300 . Once aligned, the user squeezes trigger mechanism  120  ( FIG. 1 ) on implantation instrument  100 , thereby causing grabber tips  162   c ,  162   d  to be inserted over engagement indents  906  on artificial disc  900  ( FIGS. 31 and 6 B). Once grabber tips  162  are inserted over engagement indents  906 , the user releases trigger mechanism  120 , causing grabber tips  162  to engage engagement indents  906  on artificial disc  900  ( FIG. 31 ). The user removes implant clip  300  from artificial disc  900  by opening and removing implant clip  300  from the now engaged artificial disc  900 , as shown in  FIG. 6B .  
         [0057]     As shown in  FIG. 7 , distraction instrument  950  is inserted over pins (not shown) that are secured into vertebral bodies  962 ,  964 . Artificial disc  330  is passed between the forks of distraction instrument  950  using implantation instrument  100  ( FIGS. 1A-1B ). In an alternate embodiment, guides  170  on insertion instrument  100  slidably engage slots in the forks of distraction instrument  950  to help the user guide artificial disc  330  into prepared disc space  970 . Once artificial disc  330  is in a desired location within prepared disc space  970 , the user squeezes trigger mechanism  120  ( FIG. 1A ) which releases artificial disc  330  in prepared disc space  970 . The user can determine the desired position by observing cephalad markers  168  ( FIGS. 3A-3B ) located on a surface of grabber  160 . In an alternative embodiment, implantation instrument  100  can include depth control member  173  ( FIG. 1A ) such that artificial disc  330  can be inserted into prepared disc space  970  at a predetermined depth.  
         [0058]     Implantation instrument  100  and distraction instrument  950  are removed, causing superior vertebra  962  and inferior vertebra  964  to engage artificial disc  330 .  
         [0000]     Equivalents  
         [0059]     While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.