Patent Abstract:
A surgical instrument enables dispensing of a series of fasteners within a patient&#39;s body. The device includes a magazine sized and dimensioned to hold a series of fasteners, the series of fasteners insertable through an opening at the end of the magazine. A splined guide bore is rotatably supported within the magazine, and slidingly supports a shaft having an external surface mateable with the splined guide bore to restrict radial rotation of the shaft with respect to the support about said longitudinal axis. A biasing element is connected between the support and the shaft, to urge the shaft along a longitudinal axis towards a distal end of the instrument. A ratchet is connected to the shaft and engages the magazine to permit sliding of the shaft in a direction for dispensing fasteners only, unless disengaged with the magazine.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation application of U.S. Ser. No. 13/461,159, filed May 1, 2012, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to stabilizing bones, and more particularly to securing bone screws using locking caps dispensed from a tool. 
       BACKGROUND OF THE INVENTION 
       [0003]    Bones and bony structures are susceptible to a variety of weaknesses that can affect their ability to provide support and structure. Weaknesses in bony structures have numerous potential causes, including degenerative diseases, tumors, fractures, and dislocations. Advances in medicine and engineering have provided doctors with a plurality of devices and techniques for alleviating or curing these weaknesses. 
         [0004]    In some cases, the spinal column requires additional support in order to address such weaknesses. One technique for providing support is to extend a structure between adjacent bones, the structure connected at each end to a polyaxial screw “tulip”, or yoke, the yoke connected to a bone screw inserted within the bone, the structure, yoke, and bone screw all rigidly mutually secured by a locking cap applied to the yoke. 
       SUMMARY OF THE INVENTION 
       [0005]    In accordance with the disclosure, a device for dispensing a fastener to be implanted within a patient comprises a magazine defining a longitudinal axis and having a distal opening, the magazine sized and dimensioned to hold a series of fasteners, the series of fasteners insertable through the distal opening; a support having a splined guide bore aligned with the longitudinal axis of the magazine, the support connected to the magazine to be rotatable radially with respect to the longitudinal axis; a shaft slideably disposed within the support, the shaft having an external surface mateable with the splined guide bore to restrict radial rotation of the shaft with respect to the support about the longitudinal axis; a biasing element connected between the support and the shaft, the biasing element configured to urge the shaft along the longitudinal axis in a direction towards the distal end relative to a location of the support; and a ratchet connected to the shaft and engageable with the magazine to permit sliding of the shaft in first a direction towards the distal end, to prevent sliding of the shaft in a second direction away from the distal end in a first position, and to enable sliding of the shaft in the second direction in a second position, the ratchet movable from the first position to the second position when the support is rotated radially with respect to the longitudinal axis. 
         [0006]    In embodiments thereof, the ratchet includes a plurality of ratchet engagement surfaces arranged along the longitudinal axis, and at least one ratchet pawl engageable with the shaft and the ratchet engagement surfaces; and, the ratchet further includes at least one cam engageable with the at least one ratchet pawl to engage and disengage the at least one ratchet pawl with the plurality of ratchet engagement surfaces. 
         [0007]    In further embodiments thereof, one or more projections extend at the distal end, operative to block a release of an inserted fastener; one or more projections are configured to block a release of an inserted fastener when a central axis of the fastener is axially aligned with the longitudinal axis, and to release an inserted fastener when the fastener is tilted with respect to the device, whereby the central axis of the fastener is not axially aligned with the longitudinal axis; the shaft is contactable with the first inserted fastener of the series of inserted fasteners, and is thereby configured to urge the series of inserted fasteners along the longitudinal axis towards the distal end; the shaft includes first and second shaft portions in end to end contact, the at least one ratchet pawl positioned proximate a location of the end to end contact; and, the second shaft portion includes one or more guide channels configured to guide movement of the at least one ratchet pawl. 
         [0008]    In other embodiments, the fastener is a cap for a polyaxial tulip; the device further includes one or more projections extending at the distal end, operative to block a release of an inserted cap, the one or more projections configured to engage a first portion of the cap, wherein a second portion of the cap projects from the distal end, the projecting second portion thereby being engageable with the polyaxial tulip. 
         [0009]    In yet further embodiments, one or more apertures are formed radially about a portion of the magazine, one or more posts are connected to the support and project through the one or more apertures, and the one or more posts are moveable to radially rotate the support. 
         [0010]    In another embodiment, a barrel surrounds a portion of the magazine, the barrel connectable to the one or more posts, the barrel rotatable to rotate the support; the ratchet includes one or more ratchet pawls, the ratchet pawls engageable with the magazine, the ratchet pawls movable in a direction transverse to the longitudinal axis; the one or more ratchet pawls are biased in a direction of engagement with the magazine; the magazine is provided with one or more apertures positioned to provide a visible indication of a number of inserted fasteners; and, the ratchet includes one or more ratchet pawls each provided with a ramped surface, the ratchet pawls thereby operative to permit sliding of the shaft in the first direction. 
         [0011]    In another embodiment of the disclosure, a device for dispensing a fastener to be implanted within a patient comprises a magazine defining a longitudinal axis and having a distal opening, the magazine sized and dimensioned to hold a series of fasteners, the series of fasteners insertable through the distal opening, the magazine including a plurality of ratchet engagements disposed along the longitudinal axis within an interior of the magazine; a support having a splined guide bore aligned with the longitudinal axis of the magazine, the support connected to the magazine to be rotatable radially with respect to the longitudinal axis; a shaft slideably disposed within the support, the shaft having an external surface mateable with the splined guide bore to restrict radial rotation of the shaft with respect to the support about the longitudinal axis; a biasing element connected between the support and the shaft, the biasing element configured to urge the shaft along the longitudinal axis in a direction towards the distal end relative to a location of the support; and one or more ratchet pawls connected to the shaft and engageable with the plurality of ratchet engagements, and configured to permit sliding of the shaft in first a direction towards the distal end, to prevent sliding of the shaft in a second direction away from the distal end in a first position, and to enable sliding of the shaft in the second direction in a second position, the ratchet movable from the first position to the second position when the support is rotated radially with respect to the longitudinal axis. 
         [0012]    In variations thereof, the ratchet further includes at least one cam engageable with the at least one ratchet pawl to engage and disengage the at least one ratchet pawl with the plurality of ratchet engagement surfaces; and, the device further includes one or more projections extending at the distal end, operative to block a release of an inserted fastener, the one or more projections configured to engage a first portion of the fastener, wherein a second portion of the fastener projects from the distal end, the projecting second portion thereby being connectable with an object implanted within the patient. 
         [0013]    In a yet further embodiment of the disclosure, a device for dispensing a fastener to be implanted within a patient comprises a magazine defining a longitudinal axis and having a distal opening, the magazine sized and dimensioned to hold a series of fasteners, the series of fasteners insertable through the distal opening, the magazine including a plurality of ratchet engagements disposed along the longitudinal axis within an interior of the magazine; a support having a splined guide bore aligned with the longitudinal axis of the magazine, the support connected to the magazine to be rotatable radially with respect to the longitudinal axis; a shaft slideably disposed within the support, the shaft having an external surface mateable with the splined guide bore to restrict radial rotation of the shaft with respect to the support about the longitudinal axis; a biasing element connected between the support and the shaft, the biasing element configured to urge the shaft along the longitudinal axis in a direction towards the distal end relative to a location of the support; one or more ratchet pawls each having a sloped surface and connected to the shaft and engageable with the plurality of ratchet engagements, and configured to permit sliding of the shaft in first a direction towards the distal end, to prevent sliding of the shaft in a second direction away from the distal end in a first position, and to enable sliding of the shaft in the second direction in a second position, the ratchet movable from the first position to the second position when the support is rotated radially with respect to the longitudinal axis; and one or more ratchet pawl biasing elements configured to urge the one or more ratchet pawls in a direction of engagement with the plurality of ratchet engagements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
           [0015]      FIG. 1  is a perspective view of a spine stabilization device usable with a tool of the disclosure; 
           [0016]      FIGS. 2 and 3  are perspective views of a locking cap in accordance with the disclosure; 
           [0017]      FIG. 4  is a perspective view of a dispensing tool of the disclosure; 
           [0018]      FIG. 5  is an enlarged perspective view illustrating mating portions of a tool tip and a cap, in accordance with the disclosure; 
           [0019]      FIG. 6  is an exploded side view of parts of the tool of  FIG. 4 ; 
           [0020]      FIG. 7  is an exploded perspective view of parts of the tool of  FIG. 4 ; 
           [0021]      FIG. 8  is a cross-section of the tool of  FIG. 4 , taken through a longitudinal center of the tool; 
           [0022]      FIG. 9  is an enlarged perspective view of the cam configuration of the tool of  FIG. 4 ; and 
           [0023]      FIG. 10  is a cross-section of an alternative tool of the disclosure, taken through a longitudinal center of the tool. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    As required, detailed embodiments are disclosed herein; however, it is to be understood that the disclosed embodiments are merely examples and that the systems and methods described below can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present subject matter in virtually any appropriately detailed structure and function. Further, the terms and phrases used herein are not intended to be limiting, but rather, to provide an understandable description of the concepts. 
         [0025]    The terms “a” or “an”, as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms “including” and “having,” as used herein, are defined as comprising (i.e., open language). 
         [0026]      FIG. 1  illustrates an exploded view of a connecting structure extendable between bones. A bone screw  10  is passed through a yoke  300 , in this example a polyaxial pedicle screw “tulip”. Bone screw  10  extends from yoke  300  into bone to be stabilized (not shown), for example a vertebra. In this embodiment, bone screw  10  is provided with a polyaxial head  14 , which may nest within yoke  300  at any of a wide variety of angles, enabling the medical practitioner to orient yoke  300  at a desired angle with respect to the bone. One example of screw  10  is a polyaxial pedicle screw, although other screw types may be used in combination with devices of the disclosure. A stabilizing structure, in this example rod  16 , is passed into yoke  300 , whereby head  14  and rod  16  lie below an upper surface  308  of yoke  300 , and when so disposed, may be secured by the introduction of a fastener, or cap  200 . Additional securing elements  302 ,  304  may be provided to improve a connection of head  14  and rod  16  within yoke  300 . 
         [0027]    In accordance with the disclosure, cap  200  is provided with one or more engagement tabs  202  which cooperate with mating grooves  306  within yoke  300 , to prevent separation of cap  200  from yoke  300 , once tabs  202  and grooves  306  are engaged. It should be understood that, alternatively or additionally, mating grooves  306  may be provided within cap  200 , and tabs  202  may be provided within yoke  300 . A set screw  204  threadably passes through cap  200 , and may be rotated to increase a pressure between cap  200 , head  14 , and rod  16 , to rigidly secure the assembly, thereby rigidly connecting rod  16  to a bone. 
         [0028]    When rod  16  is thus secured to another bone with a similar assembly, the two bones so connected are stabilized with respect to each other. Such stabilization is effective, for example, in the spine, connecting vertebrae; however, any bones of the body, and any number of bones, may be stabilized in this manner. Rod  16  may be constructed to be rigid or resilient, enabling a desired amount of flex between stabilized bones. 
         [0029]    In accordance with the disclosure, a plurality of caps  200  are individually discharged or dispensed from a single instrument or tool  100 . In accordance with one embodiment, for example, eight caps  200  may be dispensed. While a threaded cap may be dispensed using tool  100 , a non-threaded cap  200  as shown and described herein is advantageously dispensed, as such caps do not have the risk of cross threading, or accidental disengagement, in the manner that threaded caps do, and are more quickly installed. 
         [0030]    It should be understood that a fastener, or cap  200 , may be attached to other implants or structures as currently known, or hereinafter developed. Moreover, cap  200  may have other forms than those illustrated in the accompanying drawings. For example, they may be threaded, or may engage a yoke, nut, or other embedded structure in a different way, for example by using a snap-fit, or interference fit, while advantageously being dispensed and installed using tool  100  of the disclosure. 
         [0031]    In accordance with the disclosure, caps  200  are dispensed by a tool  100 . In the embodiment of  FIGS. 2-3 , cap  200  further includes tool flange  206 , sized and dimensioned to engage mating portions of tool  100 , as described further, below. While cap  200  of  FIGS. 2-3  is illustrative of a cap adapted to matingly engage tool  100 , as described further herein, it should be understood that tool  100  may be adapted to engage other cap designs, including the cap illustrated in  FIG. 1 . 
         [0032]    In  FIG. 4 , an embodiment of tool  100  in accordance with the disclosure includes a handle assembly  110 , a latch assembly  120  including a release knob, or latch barrel  122 , a loading tube, or magazine  160 , and a retention tip  180 . Handle assembly  110  includes a grip  112 , and a handle extension  114  and handle adapter  114 A. Caps  200  are loaded into magazine  160  by being inserted into retention tip  180 , each successive cap pushing the previously loaded caps further into magazine  160 . Caps  200  may be arranged, for example, in a tray that orients caps  200  correctly for insertion. Apertures  162  within magazine  160  provide a visible indication of loaded caps  200 , advantageously indicated by a difference in color between an exterior surface of magazine  160  and caps  200 . 
         [0033]    When magazine  160  is loaded with caps  200 , tabs  202  of the last loaded cap  200  project beyond tip  180 , whereby tabs  202  may be engaged with yoke  300 . Once thus engaged, tool  100  may be tilted to change an orientation between tip  180  and cap  200 , secured to yoke  300 , thereby enabling passage of cap  200 , and particularly to admit passage of tool flange  206  past a mating flange engagement  182  of tip  180 , releasing a cap  200  from magazine  160  and tool  100 . 
         [0034]      FIG. 5  illustrates a mating engagement between tool flange  206  and flange engagement  182 . In this embodiment, flange engagement  182  forms an interference fit with one or more portions of tool flange  206 . As explained further below, cap  200  is resiliently urged against tip  180 , thereby pressing tool flange  206  of cap  200  against flange engagement  182  of tip  180 , preventing passage of cap  200  out of tool  100 . Once a longitudinal axis of tool  100  is tilted with respect to a central bore axis of cap, portions of tool flange  206  may pass portions of flange engagement  182 , thereby releasing cap  200 . Until tool  100  is tilted while dispensing a cap  200  connected to yoke  300 , caps  200  are maintained coaxially aligned with a longitudinal axis of tool  100  by a mating shape and dimension of in interior of magazine  160  and an exterior shape and dimension of cap  200 , together with a biasing force provided by biasing member  136 . 
         [0035]    In another embodiment, tip  180  and or portions of magazine  160  are resilient, and may bend to admit passage, or facilitate passage, of cap  200  past flange engagement  182 . For example, flange engagement  182  may comprise resilient extensions. Alternatively, as shown in  FIG. 4 , tip  180  or magazine  160  may be provided with reliefs  166 ,  184 , to facilitate sufficient expansion of tip  180  or magazine  160  to enable passage of a cap  200  from tool  100 . 
         [0036]      FIG. 6  is an exploded view of tool  100 , the parts arranged, for ease of understanding, in an original axial displacement along a longitudinal axis of tool  100 , but displaced radially, with internal portions positioned externally.  FIGS. 7 and 8  may additionally be referenced with respect to the following discussion. Additionally illustrated are cover  116 , handle core  118 , handle extension  114 , and handle adapter  114 A. Portions of handle assembly  110  having reference numerals  100  to  120  are mutually connected to not rotate with respect to each other. While handle assembly  110  comprises a plurality of parts, for example for ease of manufacture, it should be understood that a single part may be used. Grip  112  is advantageously formed with a resilient material, to promote a secure manual grip, and for comfort. 
         [0037]    Handle extension  114  of handle assembly  110  is non-rotatably connected to magazine  160 , whereby rotation of handle assembly  110  causes rotation of magazine  160 . Rotatably mounted within magazine  160  are cam actuator shaft support  124  and cam actuator  126 , the latter including cam actuator shaft  128 , cam head  130 , and cam surfaces  132  (shown in  FIG. 9 ). Cam actuator shaft  128  is slidingly received within a guiding splined bore  124 A (visible in  FIG. 7 ) of shaft support  124 , whereby shaft support  124  and actuator shaft  128  rotate in unison about a common longitudinal axis, while actuator shaft  128  is slideable axially along the common longitudinal axis. While the illustrated embodiment of splined bore  128 A has a square shape, corresponding to an external shape of cam actuator shaft  128 , other mateable shapes may be employed. 
         [0038]    Latch barrel  122  is rotatably mounted about an exterior surface of magazine  160 . One or more latch posts  134  pass through a portion of latch barrel  122 , through one or more cutout portions  168  of magazine  160 , and into shaft support  124 , whereby rotation of latch barrel  122  causes rotation of shaft support  124  within magazine  160 . Cutout portions  168  are oriented radially about a longitudinal axis of tool  100 , and define an arc through which latch posts  134  may travel, thereby limiting a rotational extent of latch barrel  122  and shaft support  124 . Cutout portions  168  may be provided with a relief portion  168   a  extending along a longitudinal axis of tool  100 , whereby latch barrel  122 , latch posts  134 , and shaft support  124  may be moved axially with respect to a longitudinal axis of tool  100 , to maintain a rotational position of the foregoing parts against a biasing force. Latch barrel  122  is advantageously knurled or textured to ease manipulation thereof. 
         [0039]    Cam actuator  126  is urged towards a distal end  190  of tool  100 , in a direction towards tip  180 , by a biasing element  136  (shown in  FIGS. 8 and 10 ), for example a spring, causing cam actuator shaft  128  to slide along in an axial direction along a longitudinal dimension of tool  100 , within shaft support  124 . Cam head  130  thus bears against a pressure transferring bar or tube, in the illustrated embodiment push rod  138 , the latter bearing against any loaded caps  200 . As such, caps  120  are urged towards the distal end  190  of tool  100 , where they may be sequentially dispensed. Once a cap is dispensed, it is advantageously at least provisionally tightened to ensure it remains in connection with yoke  300  until the therapeutic medical procedure is complete. While push rod  138  is provided, it should be understood that actuator shaft  128  may be provided with sufficient length to drive caps  200  directly. 
         [0040]    In order to use tool  100  to push engagement tabs  202  into yoke  300 , and to thereafter turn cap  200  to lock engagement tabs  202  into grooves  306 , it is advantageous to prevent movement of the cap  200  backwards, further into magazine  160 . To accomplish this, one or more ratchet pawls  140  pass through ratchet guides  142  disposed within an end of push rod  138 , and thence into engagement with ratchet engagements  164  of magazine  160 . In this manner, push rod  138  is axially and radially fixed with respect to magazine  160 , and handle assembly  110 . While ratchet engagements  164  are illustrated as openings in magazine  160 , they may be formed as ledges, ridges, or other shaped surfaces which are sufficient to engage and support ratchet pawls  140 , but which do not necessarily pass through magazine  160 . When ratchet engagements  164  form apertures, these may serve as an additional indicator of caps  200  loaded, or remaining, facilitated, for example, if ends of ratchet pawls  140  are provided with a color which contrasts with a color of an exterior surface of magazine  160 . 
         [0041]    Ratchet pawls  140  are advantageously formed with ramped surfaces  140 A, whereby when a cap  200  is released, ratchet pawls  140  advance upon ramped surface  140 A through a bias force exerted by biasing element  136 , and are thereby released from engagement with ratchet engagement  164 . Accordingly, the remaining series of caps  200  may advance towards the distal end of tool  100 , until the next successive cap  200  is held by flange engagements  182 . Absent ramped surfaces  140 A, latching barrel  122  could be rotated to disengage ratchet pawls  140  to allow advancement of inserted caps  200 . In this manner, fasteners may be dispensed, even if ratchet pawls  140  are engaged with ratchet engagements  164 , but fasteners may not driven in a direction away from the distal end  190  of tool  100  unless ratchet pawls  140  are disengaged from ratchet engagements  164 . Accordingly, tool  100  may be used to push caps  200  into yoke  300  against a resisting force. Tool  100  may also be used to rotate a cap  200  within a yoke  300  against a force resistant to rotation, due to a mating engagement of an outer surface of cap  200  with an interior surface of magazine  160 . 
         [0042]    With further reference to  FIG. 9 , once a cap  200  has been dispensed, ratchet pawls  140  are withdrawn from ratchet engagements  164 , whereby cam actuator  126  and biasing element  136  may urge push rod  138  towards proximal end  190 , to thereby position the next successive cap  200  for dispensing. To withdraw ratchet pawls  140 , one or more cam surfaces  132 , within cam head  130 , are rotated to guide one or more ratchet pins  144 , each connected to a ratchet pawl  140 . The profile of each of the one or more cam surfaces  132  causes ratchet post  144  to move radially inwardly, in cooperation with cam post guide  148  within an end of push rod  138 , with respect to a longitudinal axis of tool  100 , thereby withdrawing ratchet pawl  140  from ratchet engagement  164  of magazine  160 . A ratchet biasing element  146  is advantageously provided to urge ratchet pawl  140  radially outwards, to maintain ratchet pawl  140  in engagement with ratchet engagements  164  until cam surfaces  132  are activated, and to return latch barrel  122  to a non-actuated position. It should be understood that ratchet pawls  140  may extend through ratchet guides  142 , or ratchet pawls  140  may be positioned outside of push rod  138 . 
         [0043]    To activate cam surfaces  132 , cam actuator  126  is rotated by radially rotating latch barrel  122  with respect to a longitudinal axis of tool  100 , to move posts  134 , to thereby cause a rotation of shaft support  124 . Accordingly, actuator shaft  128  rotates, turning cam head  130 , and cam surfaces  132 . Ratchet pins  144  are further guided to move radially inwards by passing through cam post guide  148 . Rotation of latch barrel  122  may be limited by either or both of a length of cutout portions  168 , or a length of a profile of cam surface  132 . To facilitate disassembly of tool  100 , for example for repair or cleaning, latch barrel may be maintained in a rotated or actuated position, while push rod  138  is fully removed following dispensing of the last loaded cap  200 . Latch posts  134  may be removed, for example by unthreading them from shaft support  124 , to release the remaining moveable parts from magazine  140 . Tool  100  may be cleaned in an assembled or an unassembled state, for example using an autoclave or gas sterilization. 
         [0044]    In accordance with an embodiment of the disclosure, to use tool  100 , latch barrel  122  is rotated to an extent of rotation according to a design of cam surface  132  sufficient to disengage or withdraw ratchet pawls  140 , for example 90 degrees. Rotation is along a direction indicated by an arrow indicia  150 , until a mark upon latch barrel  122  is aligned with indicia  150  (“Load”) on magazine  160 . In this configuration, tip  180  is pushed against a cap  200  until the cap enters magazine  160 , the cap typically resiliently held in place within a tray. Once all caps  200  are loaded, latch barrel  122  is rotated away from the “Load” position, to a “Use” position (not shown) which may also be provided as indicia upon a surface of tool  100 , to thereby release ratchet pawls  140  to reengage magazine  140 . Next, a projecting portion of cap  200  is inserted into a yoke  300 , and rotated, for example 30 degrees, to engage yoke  300 . After such engagement, tool  100  is tilted to free the engaged cap  200  from engagement with one or more projections, or mating flange engagements  182  of tip  180 , to release cap  200  from tool  100 . Following such disengagement, the next loaded cap  200  advances due to a force imparted by biasing element  136 , and the inserted cap  200  may be tensioned within yoke  300 . The newly projecting cap  200  is inserted into another yoke  300 , and the process is repeated from that point until all loaded caps  200  are dispensed and inserted within their respective yokes  300 . 
         [0045]      FIG. 10  illustrates an alternative embodiment of a tool in accordance with the disclosure, wherein handle assembly  110 A includes a t-handle, and latch post  134  is directly manipulable. While biasing element  136  is illustrated as a compression spring, it should be understood that other forms of biasing may be provided, including a torsion spring, volute spring, and compressed gas bladder. While magazine  140  of  FIG. 10  is configured to hold five caps  200 , it should he understood that any number of caps  200  may be dispensed, depending on the height of caps  200 , and a length of magazine  140 . 
         [0046]    Tool  100  may be fabricated using any known materials which are advantageously biocompatible, including for example PEEK (polyether ether ketone), ultra high molecular weight polyethylene (UHMW), titanium, stainless steel, or a cobalt chromium alloy. Other polymers, metals, alloys, or composite materials may alternatively be used, as known in the art, or hereinafter developed. One or more portions of tool  100  may be formed by extrusion, milling, forging, casting, molding, or any other method advantageously used for the materials selected and the structure intended. 
         [0047]    The tool and method of the disclosure enables increased efficiency and reduced error in applying caps for securing screws. More particularly, caps  200  may be inserted more quickly than other known methods of insertion, for example by manual installation or installation using a tool which accommodates a single cap  200 . Insertion speed is important, because it reduces the time a patient undergoes anesthesia, reducing tissue damage by reducing time during which tissue is retracted or manipulated, and reduces cost by reducing staff and operating room use time. 
         [0048]    All references cited herein are expressly incorporated by reference in their entirety. There are many different features to the present invention and it is contemplated that these features may be used together or separately. Unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. Thus, the invention should not be limited to any particular combination of features or to a particular application of the invention. Further, it should be understood that variations and modifications within the spirit and scope of the invention might occur to those skilled in the art to which the invention pertains. Accordingly, all expedient modifications readily attainable by one versed in the art from the disclosure set forth herein that are within the scope and spirit of the present invention are to be included as further embodiments of the present invention.

Technology Classification (CPC): 0