Abstract:
A cervical drill guide apparatus includes a handle assembly having a housing and an extension member attached to one end of the housing. The handle assembly includes a fixed handle and a movable handle. A distal end of the extension member includes a plurality of fingers that are radially expandable or contractible in response to relative movement between an actuation shaft and the extension tube. The fingers are adapted for releasably engaging an opening in a plate. Additionally, a guide member is releasably attached to the distal end portion of the cervical drill guide apparatus. The guide member includes at least one opening therethrough for receiving a drill or other surgical instrumentation. The extension member may be rotatable in relation to the housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present disclosure claims the benefit of and priority to Provisional Patent Application No. 60/721,484, filed on Sep. 29, 2005, the entire contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND  
       [0002]     1. Technical Field  
         [0003]     The present disclosure relates generally to orthopedic spinal surgery and in particular to a cervical drill guide apparatus and methods for guiding a cervical drill, bone screw, or other instrumentation during spinal surgery.  
         [0004]     2. Background of Related Art  
         [0005]     The spinal column is a complex system of bones and connective tissues that provide support for the human body and protection for the spinal cord and nerves. The adult spine is comprised of twenty-four vertebral bodies, which are subdivided into three areas, including seven cervical vertebrae, twelve thoracic vertebrae and five lumbar vertebrae. Between each vertebral body is an intervertebral disc that cushions and dampens the various translational and rotational forces exerted upon the spinal column.  
         [0006]     There are various disorders, diseases, and types of injury which the spinal column may experience in a lifetime. These problems may include, but are not limited to, scoliosis, kyphosis, excessive lordosis, spondylolisthesis, slipped or ruptured discs, degenerative disc disease, vertebral body fracture, and tumors. Persons suffering from any of the above conditions typically experience extreme or debilitating pain and often times diminished nerve function.  
         [0007]     One of the more common solutions to any of the above-mentioned conditions involves a surgical procedure known as a spinal fusion. Spinal fusion involves fusing two or more vertebral bodies together to eliminate motion at the intervertebral disc or joint. To achieve spinal fusion, natural or artificial bone, along with a spacing device, replace part or all of the intervertebral disc to form a rigid column of bone. Mechanical hardware is connected to the adjacent vertebrae to stabilize the spine in that area while the bone grows and the fusion occurs.  
         [0008]     The mechanical hardware used to immobilize the spinal column typically involves a series of bone screws and metal rods or plates. When the spine surgery is performed posteriorly, it is common practice to place pedicle bone screws into the vertebral bodies and then connect a metal rod between the screws, thus creating a rigid structure between adjacent vertebral bodies. When the spinal surgery is performed anteriorly, it is common practice to attach a thin metal plate directly to the vertebral bodies and secure it to each vertebral level using one or more bone screws. For the remainder of this disclosure, references to spinal surgery will be referring to the anteriorly performed surgery in which a metal plate is secured directly to the vertebrae using bone screws.  
         [0009]     Because the spine is routinely subject to mechanical loads which cycle during movement, a primary concern of physicians performing metal plate implantation surgeries, as well as of the patients in whom the implants are placed, is the risk of screw pullout. This is of particular concern in the cervical region because of the critical vessels that abut the anterior surfaces of the cervical spine. Screw pullout occurs when the cylindrical portion of the bone that surrounds the inserted screw fails. A bone screw that is implanted into the vertebrae perpendicular to the plate is particularly weak because the region of the bone that must fail for pullout to occur is only as large as the outer diameter of the screw threads. Screws which are angled inward towards one another, also referred to as “toe-nailed”, or ones which diverge within the bone have been found to greatly reduce the likelihood of screw pull out because the region of bone that must fail is increased as compared to that of screws implanted perpendicular to the plate.  
         [0010]     The metal plates used to connect the vertebrae in spinal surgery are well known in the art. These plates may define any number of openings configured for receiving bone screws. The openings for receiving the screws may include a beveled or angled edge for more securely receiving the angled screws. The metal plates may also include openings or grooves for releasably receiving an elongated handle member for maintaining the metal plate during implantation. Because the metal plates used in spinal fusion are relatively small and awkward to handle, elongated handle members have been developed for releasably engaging the metal plates such that they may be held in position while the bone screws are being applied. The elongated handle members generally include a handle assembly for grasping the handle member and an extension member connected thereto. The distal end of the extension member may include any number of clips, protrusions, tabs or the like for releasably engaging the metal plate.  
         [0011]     As discussed above, positioning of the bone screws used to secure the metal plate to the vertebrae is important to preventing screw pullout, and thus a successful spinal fusion. The elongated handle members may further be configured to include a guide member for guiding the drill, screws, or other instrument for assisting a surgeon in positioning the bone screws during implantation of the metal plate. Commonly owned U.S. Pat. No. 7,094,242 to Ralph et al., discloses such a device, and is incorporated herein by reference in its entirety.  
         [0012]     Conventional drill guides generally include a handle assembly fixedly attached to the proximal end of an extension member. The distal end of the extension member generally includes an assembly configured for releasable engagement with a metal plate. The extension member may be configured to include one or more guide members. Alternative drill guides include a guide member that is independently attached to the mounting assembly. During procedures involving surgeons with different preferences, more than one surgeon or the use of multiple instruments within the surgical field, the handle assembly of the drill guide often is oriented in a less than convenient position. Because the handle assembly is fixedly attached to the extension member, the orientation of the handle assembly cannot be adjusted. Furthermore, because the guide members are affixed to a mounting plate or incorporated in the extension member, the guide members cannot be removed or replaced. In the event that the guide member malfunctions, or the procedure calls for an alternate guide member configuration, the entire drill guide must be replaced.  
         [0013]     Therefore, it would be beneficial to have a drill guide apparatus including a handle assembly that can be selectively positioned about an extension member prior to or during implantation of a metal plate. It would further be beneficial to have a guide member that can be removably affixed to the drill guide apparatus.  
       SUMMARY  
       [0014]     A cervical drill guide apparatus according to one embodiment of the present disclosure includes a handle assembly having an extension tube extend distally therefrom. The handle assembly includes a housing with a fixed handle and a movable handle. The movable handle is pivotable with respect to the fixed handle. A biasing mechanism is located between the fixed handle and the movable handle for biasing the movable handle away from the fixed handle, thereby defining a first position. A latch is disposed on a proximal portion of the handle assembly and permits locking the fixed handle and the movable handle in a second position after a practitioner has pivoted the movable handle towards the fixed handle.  
         [0015]     Pivotable movement of the movable handle towards the fixed handle causes an actuation shaft to move distally through the extension member. At the distal end of the extension member, a plurality of slits defines a plurality of fingers that are radially expandable in relation to the longitudinal axis of the extension member. The fingers are adapted and configured for releasably engaging an opening in a bone plate. In addition, a mount assembly is located at the distal end of the extension member. The mount assembly releasably retains a guide member. The guide member includes at least one opening therethrough for receiving a drill bit or other surgical instrument. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     Embodiments of the presently disclosed cervical drill guide apparatus are described herein with reference to the accompanying drawings, wherein:  
         [0017]      FIG. 1  is an isometric view of an embodiment of the drill guide apparatus of the present disclosure including a handle assembly, extension member, mounting assembly and guide member;  
         [0018]      FIG. 2  is a cross-sectional side view of the drill guide apparatus of  FIG. 1 ;  
         [0019]      FIG. 3  is an exploded side view of the drill guide apparatus of  FIGS. 1 and 2  including a metal plate;  
         [0020]      FIG. 4A  is a front elevational view of the drill guide apparatus of  FIGS. 1-3  including a metal plate attached thereto;  
         [0021]      FIG. 4B  is an enlarged view of portion  4 B of the drill guide apparatus of  FIG. 4A ;  
         [0022]      FIG. 5A  is a side view of the drill guide apparatus of  FIGS. 1-3  in a first or open position;  
         [0023]      FIG. 5B  is a cross-sectional view of the distal end of the drill guide apparatus of  FIG. 5A  taken along section line  5 B- 5 B;  
         [0024]      FIG. 6A  is a side view of the drill guide apparatus of  FIGS. 1-3  in a second or closed position;  
         [0025]      FIG. 6B  is a cross-sectional view of the distal end of the drill guide apparatus of  FIG. 6A  taken along section line  6 B- 6 B;  
         [0026]      FIG. 7  is an enlarged side view of the distal end of the drill guide apparatus of  FIGS. 1-3 ;  
         [0027]      FIG. 8A  is a side view of the guide member of  FIGS. 1-4B ;  
         [0028]      FIG. 8B  is an isometric view of the guide member of  FIG. 8A ;  
         [0029]      FIG. 9A  is a side view of an alternate embodiment of a guide member of the present disclosure;  
         [0030]      FIG. 9B  is an isometric view of the guide member of  FIG. 9A ;  
         [0031]      FIG. 10A  is a side view of another alternate embodiment of a guide member of the present disclosure;  
         [0032]      FIG. 10B  is an isometric view of the guide member of  FIG. 10A ;  
         [0033]      FIG. 11A  is a side view of yet another alternate embodiment of a guide member of the present disclosure; and  
         [0034]      FIG. 11B  is an isometric view of the guide member of  FIG. 11A .  
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0035]     While the presently disclosed cervical drill guide apparatus will be described more fully hereinafter with reference to the accompanying drawings, in which particular embodiments are shown, it is to be understood at the outset that persons skilled in the art may modify the apparatus herein described while achieving the functions and results of this apparatus. Accordingly, the descriptions that follow are to be understood as illustrative and exemplary of specific structures, aspects, and features within the broad scope of the present disclosure and not as limiting of such broad scope. Like numbers refer to similar features of like elements throughout.  
         [0036]     Referring to  FIG. 1-3 , an illustrative embodiment of the presently disclosed drill guide apparatus is illustrated therein and generally designated as drill guide  100 . Drill guide  100  includes a handle assembly  110 , an extension member  120 , a mount assembly  130 , and a removably attachable guide member  140 . In this disclosure, as is traditional, the term “proximal” will refer to the end of the drill guide  100  (or other element) which is closer to the user, while the term “distal” will refer to the end which is further from the user.  
         [0037]     With reference to  FIGS. 1 and 2 , handle assembly  110  forms a pistol-like grip configured such that a surgeon may operate drill guide  100  with a one hand. Handle assembly  110  includes a housing  112 , a fixed handle  114 , and a movable handle  116 . Movable handle  116  is pivotably connected to housing  112  by handle pin  115 . Movable handle  116  includes a tip  116   a  located at a proximal end thereof that extends through housing  112 . Tip  116   a  of movable handle  116  operably engages actuation shaft  126 . Handle assembly  110  further includes a latch  119  slidably mounted to housing  112 . Leaf springs  118   a ,  118   b  are fastened to fixed handle  114  and movable handle  116  to bias handle assembly  110  towards a first or open position, wherein movable handle  116  is spaced apart from fixed handle  114 . In alternate embodiments, movable handle  116  may be biased using any conventional biasing mechanism including, but not limited to, springs, hydraulics, and pneumatics.  
         [0038]     Referring now to  FIGS. 2 and 3 , actuation shaft  126  extends substantially the length of drill guide  100 . Actuation shaft  126  includes a proximal end  126   a  and a distal end  126   b . Proximal end  126   a  is configured to be operably received within housing  112 . Proximal end  126   a  is further configured to engage tip  116   a . Proximal end  126   a  engages tip  116   a  such that articulation of movable handle  116  about handle pin  115  towards fixed handle  114  (i.e. pivotable movement of handle  116 ) causes longitudinal movement of actuation shaft  126  in the distal direction through extension member  120 . In the present embodiment, proximal end  126   a  is configured to receive tip  116   a  therethrough ( FIG. 1 ). A locking pin  125  may further be used to secure proximal end  126   a  to tip  116   a  of movable handle  116 . Proximal end  126   a  may also be configured to connect to tip  116   a  using mechanical fasteners and/or geared surfaces. Actuation shaft  126  extends from within housing  112  and extends to a distal end  126   b  located within extension member  120 . Proximal end  126   a  further includes a collar  127  for preventing actuation shaft  126  for from over-extending distally through housing  112 .  
         [0039]     Still referring to  FIGS. 2 and 3 , extension member  120  is an elongated tubular member having a proximal end  120   a  and a distal end  120   b . Proximal end  120   a  is rotatably mounted to housing  112 . Extension member  120  includes a collar  122  for selectively rotating extension member  120  relative to handle assembly  110 . Extension member  120  may be configured to rotate 360° relative to handle assembly  110 . Extension member  120  may be configured with predetermined stops or positions for selectively positioning extension member  120  relative to handle assembly  110 . A metal plate  20  may be releasably engaged to distal end  120   b  such that rotation of extension member  120  also rotates plate  20 . Collar  127  may include graduations or markings for selectively aligning or positioning handle assembly  110  and extension member  120 .  
         [0040]     Extension member  120  is configured to permit the longitudinal movement of actuation shaft  126  therein. Distal end  120   b  is configured for releasable attachment to metal plate  20 . Distal end  120   b  of extension member  120  includes a tapered end portion  122  defining a plurality of fingers  124  ( FIG. 7 ) that are radially expandable in relation to extension member  120 . Fingers  124  are sized to be received within one or more openings formed on metal plate  20  when fingers  124  are in a first or relaxed position. Fingers  124  include a ridge or lip  125  ( FIG. 4B ) for releasably engaging an opening formed in metal plate  20  when fingers  124  are in a second or expanded position ( FIGS. 4A and 6B ). Fingers  124  of expansion member  120  and distal end  126   b  are configured such that longitudinal advancement of actuation shaft  126  through expansion member  120  causes radial expansion of fingers  124  ( FIG. 6B ). Expansion member  120  and actuation shaft  126  are further configured such that retraction of actuation shaft  126  within expansion member  120  causes fingers  124  to return to a first or relaxed position ( FIG. 5B ). Thus, the disengaging drill guide  100  from metal plate  20 .  
         [0041]     Referring now to  FIG. 7 , distal end  120   b  further includes a mount assembly  130  for removably attaching guiding member  140  to drill guide  100  ( FIG. 3 ). Mount assembly  130  includes a first member  132  and a second member  134 . First and second members  132 ,  134  each include a proximal end  132   a ,  134   a  and a distal end  132   b ,  134   b , respectively. First member  132  is fixedly attached to distal end  120   b  using any conventional means, including but not limited to adhesives, welding and fasteners. Second member  134  is pivotably mounted to first member  132 . A spring mechanism  135  biases distal end  134   b  of second member  134  against distal end  132   b  of first member  132 . Proximal end  134   a  of second member  134  may define a lever or tab  136  ( FIG. 1 ) for effecting the separation of distal ends  132   b ,  134   b  of first and second members  132 ,  134 , respectively, when depressed.  
         [0042]     Second member  134  of mount assembly  130  is configured for slidably receiving guide member  140 . Second member  134  may further be configured to engage first member  132  such that once guiding member  140  has been received on second member  134  guide member  140  cannot be removed without depressing lever  136 . First and/or second members  132 ,  134  may include a coating, for example rubber, and/or be configured with ridges, grooves, or knurls that more securely retains guide member  140 .  
         [0043]     With reference now to  FIGS. 3, 8A , and  8 B, guide member  140  includes a base  142  having a proximal end  142   a  and a distal end  142   b . Base  142  defines a slot  144  for slidably receiving second member  134  of mount assembly  130 . Slot  144  includes a closed distal end  144   b  and an open proximal end  144   a . Slot  144  may be configured for secure engagement to second member  134  of mount assembly  130 . Slot  144  may include a coating or be configured with ridges, grooves, or knurls corresponding to those found on first and/or second members  132 ,  134  that more securely retains guide member  140  to mount assembly  130 . Base  142  and slot  144  are configured such that when guide member  140  is secured to mount assembly  130  distal end  142   b  of guide member  140  is aligned with radial expandable fingers  124  formed in distal end  120   b.    
         [0044]     Base  142  of guide member  140  further defines a number of openings extending therethrough. Proximal end  142   a  of guide member  140  defines three openings “A”, “B”, “C”. Distal end  210   b  of guide member  140  defines a single opening “D”. Openings “A”, “B”, “C” extend into and through base  142  and converge as single opening “D” in distal end  142   b  of guide member  140 . Openings “A”, “B”, “C” are configured to enable a surgeon to secure a screw and/or use a drill or other instrument at three different angles relative to metal plate  20 . Center opening “B” is configured perpendicular to metal plate  20 , while each of openings “A”, “C” is configured at opposing angles relative to metal plate  20 . Openings “A”, “C” allow guide member  140  to be used to install bone screws in a toe-nailed manner as described above. Openings “A”, “C” may be symmetrically formed relative to opening “B”. Opening “A”, “C” may also be configured at any angle relative to a releasably engaged metal plate  20 . Because guide member  140  is removable from drill guide  100 , guide member  140  may be replaced if it becomes damaged or to better suit the needs of the procedure being performed.  
         [0045]     With reference to  FIGS. 4A-6B , drill guide  100  releasably connects to metal plate  20  through actuation of handle assembly  110 . When handle assembly  110  is in a first or open position, an opening in metal plate  20  receives fingers  124 . Articulation of movable handle  116  about handle pin  115  towards fixed handle  114  from a first or open position ( FIG. 5A ) to a second or closed position ( FIG. 6A ) causes actuation shaft  126  to advance distally through extension member  120 . As described above, engagement of distal end  126   b  of actuation shaft  126  cause the expansion of radial expandable fingers  124  ( FIGS. 4B and 6B ).  
         [0046]     With continued reference to  FIGS. 5A and 6A , in the first or open position ( FIG. 5A ), movable handle  116  is at maximum separation from fixed handle  114 . This open position also corresponds to an unlocked and retracted state of actuation shaft  126 . In the first position proximal end  126   a  of actuation shaft  126  extends beyond latch  119  slidably attached to housing  112  of handle assembly  110 . While handle assembly  110  is in the first position latch  119  is also in a first or down position. In this position, proximal end  126   a  inhibits latch  119  from being slid into a locked position.  
         [0047]     When a surgeon squeezes movable handle  116  toward fixed handle  114 , distal end  116   b  of movable handle  116  advances actuation shaft  126  through extension member  120 . As leaf springs  118  bias movable handle  116  and fixed handle  114  towards an open position, a surgeon must continue to squeeze movable handle  116  and fixed handle  114  towards each other to maintain the advanced position for shaft  126 . To facilitate the use of drill guide  100 , however, latch  119  may be used for releasably locking shaft  126  in a nearly fully advanced position. This obviates the need for a surgeon to continue to squeeze handles  114 ,  116  after advancement of actuation shaft  126  has occurred. Instead, the surgeon&#39;s thumb may move latch  119  into abutment with proximal end  126   a . Latch  119  remains in place due to the backward pressure applied by proximal end  126   a  against it. To release handle assembly  110  movable handle  116  is retracted sufficiently to remove the backward pressure applied by proximal end  126   a , thus, allowing latch  119  to be returned to a first or down position.  
         [0048]     Referring now to  FIGS. 9A-11B , shown are alternate embodiments of guide member  140 . Guide member  240 ,  340 ,  440  are substantially similar to guide member  140 . Guide members  240 ,  340 ,  440  each include a base  242 ,  342 ,  442  defining a slot  244 ,  344 ,  444 , respectively. Slots  244 ,  344 ,  444  each have a proximal end  244   a ,  344   a ,  444   a , and a distal end  244   b ,  344   b ,  444   b , respectively. Guide member  240  includes only a single opening “E” extending therethrough, while guide members  340 ,  440  each include two openings “F”, “G”, “H”, “I”, respectively. Guide members  340 ,  440  are substantially similar except that slot  344  of guide member  340  is positioned within the same plane as that defined by openings “F”, “G”, while slot  444  of guide member  440  extends in a plane parallel to that formed by openings “H”,  
         [0049]     In an alternate embodiment, guide members  140 ,  240 ,  340 ,  440  may include any number of openings sized to receive a drill, bone screw or other instrument. Guide members  140 ,  240 ,  340 ,  440  may include adjustable openings for selectively guiding the drill, bone screw or other instrument.  
         [0050]     While there has been described and illustrated specific embodiments of the drill guide apparatus, it will be apparent to those skilled in the art that variations and modifications are possible without deviating from the broad spirit and principle of the present disclosure. The disclosure, therefore shall not be limited to the specific embodiments discussed herein.