Abstract:
An apparatus for persuading an orthopedic rod into position in an orthopedic device such as an implant or coupling element is disclosed. The apparatus includes a body, a pusher member and a trigger slidingly coupling the pusher member to the body. The pusher member includes a slide and sleeve attached to the slide. The sleeve includes at least one pusher bar. A ratchet controls the translation of the pusher member along the body to urge the rod into position in the orthopedic device. The pusher member and body define a cannula so that a fastener may be inserted once the rod is in position. The apparatus is operable via a single hand. In addition, a method of urging an orthopedic rod into a recess of an orthopedic device using the rod persuader is provided.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an instrument for urging an orthopedic rod into a recess in an orthopedic device and more particularly, to an instrument for securing a spinal rod to a coupling element. 
     The spinal column is a highly complex system of bones and connective tissues that provides support for the body and protects the delicate spinal cord and nerves. The spinal column includes a series of vertebral bodies stacked one atop the other, each vertebral body including an inner or central portion of relatively weak cancellous bone and an outer portion of relatively strong cortical bone. Situated between each vertebral body is an intervertebral disc that cushions and dampens compressive forces exerted upon the spinal column. A vertebral canal containing the spinal cord and nerves is located behind the vertebral bodies. 
     There are many types of spinal column disorders, including scoliosis (abnormal lateral curvature of the spine), kyphosis (abnormal forward curvature of the spine, usually in the thoracic spine), excess lordosis (abnormal backward curvature of the spine, usually in the lumbar spine), spondylolisthesis (forward displacement of one vertebra over another, usually in a lumbar or cervical spine) and other disorders caused by abnormalities, disease or trauma, such as ruptured or slipped discs, degenerative disc disease, fractured vertebra, and the like. Patients that suffer from such conditions usually experience extreme and debilitating pain, as well as diminished nerve function. 
     Surgical techniques commonly referred to as spinal fixation use surgical implants and/or mechanical immobilization to fuse two or more vertebral bodies of the spinal column. Spinal fixation may also be used to alter the alignment of adjacent vertebral bodies relative to one another so as to change the overall alignment of the spinal column. Such techniques have been used effectively to treat the above-described conditions and, in many cases, to relieve pain. 
     One spinal fixation technique involves immobilizing the spine using orthopedic stabilizing rods, commonly referred to as spine rods, which are positioned generally parallel to the spine. This may be accomplished by exposing the spine posteriorly and fastening bone screws to the pedicles of vertebral bodies. The pedicle screws are generally placed two per vertebra and serve as anchor points for the spine rods. Coupling elements or implants adapted for receiving a spine rod therethrough are then used to join the spine rods to the pedicle screws. A set screw or fastener then fastens the spine rod into a seat in a coupling element. 
     Instruments are utilized for inserting a spine rod into position within an orthopedic device such as a coupling element. Surgeons have encountered considerable difficulty when attempting to use these instruments to insert a spine rod into the seat of the coupling element and then inserting a fastener to secure the set up. For example, U.S. Pat. No. 5,910,141 to Morrison provides a rod introduction apparatus capable of laterally aligning a rod with an implant and vertically advancing the rod into position in the implant. The instrument, however, is difficult to use since it requires two hands, one hand to hold the instrument while it clamps the implant and one hand to operate the lateral alignment and vertical alignment means to properly position the rod in the implant. 
     In addition, U.S. Pat. No. 5,020,519 to Hayes et al. discloses an instrument for seating a spine rod into a hook. The instrument grips the hook with teeth and clamps the hook between the jaws. The thumb wheel must be rotated to shift the pusher thereby urging the spine rod into the hook. Again, it is difficult to utilize this instrument with a single hand. 
     There remains a need for improved instruments for urging or persuading spinal rods into position in orthopedic devices such as coupling elements or implants. In particular, there remains a need for spinal rod persuaders that may be effectively utilized with one hand. Moreover, there is a need for a simple design that both holds the coupling element stationary while persuading the rod into position. There is a further need for a rod persuader that locks as the rod is advanced into position. It is advantageous for a rod persuader to be easily removed from gripping the coupling element after the rod is properly positioned. It is further advantageous to provide a cannula in the rod persuader in which a set screw or other fastener may be inserted and delivered to the coupling element while the rod persuader is gripping the coupling element and rod. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, a rod persuader or an apparatus for urging an orthopedic or spinal rod into a recess or seat on an orthopedic device such as an implant, coupling element, or pedicle screw system is provided. The apparatus includes a body that is releasably attachable to the orthopedic device, pusher member and a trigger slidingly coupling the pusher member to the body. 
     The trigger may be actuated to translate the pusher member into contact with the rod and continue translating the pusher member until the rod is urged into recess of the orthopedic device. The pusher bar comprises a slide coupled to the body via the trigger and a sleeve attached to the slide so that the slide and sleeve translate together. Additionally, the sleeve includes at least one pusher bar integral with the sleeve and for accommodating the rod upon contact. Furthermore, the rod persuader may include a grip extending from the body and a handle extending from the trigger so that the rod persuader may be comfortably held in one hand. The handle is movable toward the grip to actuate the trigger. 
     According to another aspect of the invention, the rod persuader has a pair of fingers extending from an end of the body. The fingers are adaptable to releasably grip the orthopedic device. The fingers are elastic members that are separable to receive and grip the orthopedic device therebetween. The fingers may further include projections that cooperate with recess on the orthopedic device that allows the rod persuader to snap onto the orthopedic device. Additionally, the sleeve may include portions such as arms that prevent the fingers of the body from separating while gripping the orthopedic device as the sleeve is advanced. 
     According to another aspect of the invention, the rod persuader defines a cannula for receiving a fastener and a driver to secure the rod to the orthopedic device. The body and/or the pusher member may have channels which together form the cannula. 
     According to another aspect of the invention, a rod persuader or apparatus for urging and securing an orthopedic rod to an orthopedic device is provided. The apparatus includes a body releasably attachable to the orthopedic device, a pusher member coupled to the body via a trigger, and a ratchet. Actuation of the trigger translates the pusher member into contact with the rod and urges the rod into the recess of the orthopedic device, the ratchet controls the translation of the pusher member in steps so that after each step, the ratchet locks into position to prevent the pusher member from reverting backwards. 
     The pusher member comprises a slide slidingly coupled to the body, a sleeve attached to the slide, and at least one pusher bar integral with the slide. A grip may extend from the body and a handle may extend from the trigger. An elastic member is operatively associated with the grip and handle to hold the handle in a normally open position so that moving the handle toward the grip actuates the trigger to advance the ratchet. Thus, the elastic member locks the ratchet in position at each step. According to another aspect of the invention, the ratchet is attached to the handle or the grip. The ratchet comprises a rack having a plurality of female teeth. Each of the teeth on the rack corresponds to one step of the ratchet. The rack further includes a hinge connecting the rack to the grip or the handle and a male tooth extending opposite the female teeth from the handle or the grip and cooperating with the female teeth. Thus, as the handle is moved toward the grip, the male tooth is advanced to the first female tooth and locked into position. The male tooth advances along the rack of the female teeth each time the handle is moved and the male tooth locks in at each step. As this occurs, the pusher member translates in steps to urge the rod into position. The ratchet is unlocked by rotating the rack about the hinge. 
     According to yet another aspect of the invention, the ratchet comprises a plurality of female teeth defined in the pusher member or the body and a male tooth extending opposite the female teeth from the body or the pusher member. Moving the handle, thus actuates the trigger to translate the pusher member and advance the male tooth along the female teeth, step-by-step, locking in at each step. A tab extends from the body and is operable to unlock the ratchet. In one aspect of the invention, the pusher member includes a slide coupled to the body via the trigger, a sleeve attached to the slide, and at least one pusher bar for direct contact with the rod. 
     In accordance with another aspect of the invention, the body may further include a pair of fingers for releasably gripping the orthopedic device. The sleeve includes portions such as a pair of arms for preventing the fingers of the body from separating while holding the orthopedic device when the sleeve is translated. The rod persuader also includes a cannula formed by the channels of the slide and body. The pusher bar further defines a recess for accommodating the rod. 
     According to yet another aspect of the invention, an apparatus for securing a spinal rod to a pedicle screw is provided. The apparatus includes a generally longitudinally body defining a channel, a generally longitudinal pusher member defining a channel, a cannula formed by the channels, a ratchet, a grip extending from the body, a trigger slidingly coupling the pusher member to the body, a handle extending from the trigger, and a handle extending from the body. The handle is movable toward the grip to actuate the trigger and thereby translate the pusher member toward the spinal rod and into contact therewith. The ratchet controls the translation of the pusher member and rod in steps, locking at each step. An elastic member is associated with the grip and handle to return the handle back to a normally open position after it has been moved. 
     The apparatus may further include a pair of elastic fingers extending from the body that are separable to receive and grip the pedicle screw. The pusher member may include a slide attached to the body via the trigger, a sleeve and at least one pusher bar. The sleeve may include a pair of arms extending therefrom for preventing the fingers from separating. 
     According to another aspect of the invention, the ratchet includes a plurality of female teeth and a male tooth. The female teeth may be defined on a rack attached to the handle or grip via a hinge, or the female teeth may be defined in the slide or the body. Accordingly, the male tooth extends opposite the female teeth at the grip or handle, or the male tooth is defined opposite the female teeth in the body or slide. 
     According to yet another aspect of the invention, a method for securing an orthopedic rod to an orthopedic device using a rod persuader including a body having a grip extending therefrom, a pusher member and a trigger coupling the pusher member to the body and having a handle extending therefrom is provided. The method includes the steps of holding the rod persuader in a single hand, engaging the orthopedic device via a pair of fingers extending from the body, displacing the handle toward the grip to actuate the trigger and thereby advance the pusher member, contacting the rod with the pusher member, displacing the handle further to advance the rod into the seat of the orthopedic device, securing the rod to the orthopedic device and releasing the rod persuader from the orthopedic device. 
     In accordance with another aspect of the invention, the engagement of the orthopedic device further includes contacting the fingers of the body with the orthopedic device and applying a force to the body to separate the fingers allowing for insertion of the orthopedic device between the fingers. The securing step further includes inserting a fastener into the cannula and using a driver to tighten the fastener to secure the rod to the orthopedic device. 
     According to another aspect, the method further includes removing the driver and removing the apparatus from the orthopedic device by applying a force to the body away from the orthopedic device. 
     In accordance with another aspect of the invention, a method for securing a rod to an orthopedic device is provided. The method utilizes a rod persuader including a body with a grip, a pusher member, a trigger with a handle, a ratchet, and an elastic member connecting the handle to the grip. The method includes holding the rod persuader in a single hand, engaging the orthopedic device via fingers on the body, displacing the handle to actuate the trigger and advance the ratchet one step, and thereby translate the pusher member, locking the ratchet in position at the step, and repeatedly displacing the handle to advance the rod into position step by step. 
     The engaging step may include contacting the fingers with the orthopedic device and applying a force to the body to separate the fingers to allow for insertion of the orthopedic device there between. 
     According to another aspect, the securing step includes inserting a fastener into the cannula and using a driver to tighten the fastener to secure the rod to an orthopedic device. Finally, the rod persuader is released from the orthopedic device by unlocking the ratchet and applying a force to the body away from the orthopedic device to separate the fingers thereby releasing the rod persuader. 
     The method may further include inserting a fastener into the cannula and using a driver to tighten the fastener to secure the rod to the orthopedic device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a front perspective view of an instrument for urging a spinal rod in the open position in accordance with the present invention. 
     FIG. FIG.1B is a front perspective view of the instrument of FIG. 1A in the closed position. 
     FIG. 1C is a front perspective close-up view of section C—C of FIG.  1 A. 
     FIG. 1D is a top perspective close-up view of the sleeve, arms, rod and orthopedic device in accordance with the present invention. 
     FIG. 1E is a front perspective view of the rod fully secured to the orthopedic device. 
     FIG. 2 is a front perspective view of a body in accordance with the present invention. 
     FIG. 3 is a front perspective view of a slide in accordance with the present invention. 
     FIG. 4 is a front perspective view of a sleeve in accordance with the present invention. 
     FIG. 5 is a front perspective view of a trigger in accordance with the present invention. 
     FIG. 6A is a front perspective view of another embodiment of the invention, showing an instrument for urging a rod with a ratchet in the open position. 
     FIG. 6B is a front perspective view of the instrument of FIG. 6A in the closed position. 
     FIG. 7A is a front perspective view of another embodiment of the invention, showing an instrument for urging a rod with a ratchet in the open position. 
     FIG. 7B is a front perspective view of the instrument of FIG. 7A in the closed position. 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1A though  1 D show an instrument for persuading a rod into  114  a seator recess  102  of an orthopedic device or a coupling element  104 . The instrument comprises a generally longitudinal body  200 , a slide  300 , a sleeve  400  and a trigger  500 , each illustrated separately in FIGS. 2,  3 ,  4 , and  5  respectively. The slide  300  and sleeve  400  together form a pusher member. 
     Referring now to FIGS. 1A-1E and  2 , the body  200  defines a first end  202  and a second end  204 . A pair of fingers  206  extend from the second end  204  of the body  200 . The fingers  206  each have an interior wall  208  which define indentations  210  and notches  211  that correspond to the shape of the coupling element  104 . As shown in FIG. 1E, the coupling element  104  defines grooves  105  for receiving notches  211 . The fingers are rigid, but also elastic so that they act in a springing motion so that the application of a force will separate the fingers. Thus, a force may be applied to the body in order to insert the coupling element  104  between the fingers  206 , as shown in FIG.  1 D. Once in position, the fingers  206  securely grip the coupling element  104  via the grooves  105  by the spring motion. 
     The body  200  further defines a channel  212  extending longitudinally on its top side from the first end  202  through the middle area of the body. The channel  212  ends at an abutment  214  located at the second end  204 . The abutment  214  projects vertically higher than the first end  202  of the body. The fingers  206  extend longitudinally from opposite sides of the abutment  214 . 
     In a preferred embodiment a joint  216  is provided extending at an angle from the second end  204 . A pistol grip  218  with thumb rest  219  may be attached to the second end  204  at the joint  216  via welding, bolting or any other method of attaching. In an alternate embodiment, the grip  218  and the body  200  may be integral and therefore the body  200  and grip  218  would be formed of a single piece. The body  200  further defines a pair of threaded holes  220  to receive screws  106 . A notch  222  extends downwards from the area of the holes  220 . 
     Referring now to FIGS. 1A-D and  3 , the slide  300  has a first end  302  and a second end  304 . The first end defines a pair of threaded holes  306  and the second end defines a pair of threaded holes  308 . The slide  300  further defines a channel  310  extending longitudinally on its bottom side along the entire length of the slide. 
     FIGS. 1A-1D and  4  show the sleeve  402 . The sleeve  400  is generally shaped like a square column defining a first end  402  and a second end  404  and having a pair of opposite sides  406 , a top side  408  and a bottom side  410 . The first end  402  defines holes  412  on either side  406  of the sleeve  400 . A pair of arms  414  extend longitudinally from opposite sides  406  at the second end  404  of the sleeve  400 . A pusher bar  416  extends longitudinally from the top side  408  of the sleeve  400 , between the arms  414 . The pusher bar  416  defines a groove  418  for accommodating the spine rod. 
     FIGS. 1A-1D and  5  show the trigger  500  having a pair of branches  502  and a bottom piece  504  connecting the branches  502 . Each branch defines an upper hole  506  and a lower hole  508 . The inside surface of the bottom piece  504  has an indentation  510 . The outside surface of the bottom piece  504  also defines a joint  512  extending therefrom. In a preferred embodiment, a handle  514  is attached to the trigger at the joint  512  via welding, bolting or any other method of attaching. In addition, the handle  514  and trigger  500  may be integral so that the handle  514  and trigger  500  together are formed of a single piece. 
     As illustrated in the FIGS., the instrument  100  comprises the body  200 , the slide  300 , the sleeve  400  and the trigger  500 . The trigger  500  connects the slide  300  to the body  200 , so that the slide and body are generally parallel. The notch  222  at the first end  202  of the body fits into the indentation  510  of the trigger  500 . Lower holes  508  of the trigger are generally aligned with threaded holes  220  of the body. Screws  106  secure the trigger  500  to the body  200  via the holes  508 ,  220 . 
     Upper holes  506  of the trigger are generally aligned with threaded holes  306  of the slide. Screws  108  secure the trigger  500  to the slide  300  via holes  506 ,  306 . Thus, the slide  300  fits on top of the body  200  and extends the length from the first side  202  of the body  200  to a point just past the middle of the body  200 . There is room for the slide to advance longitudinally forward on top of the body toward the abutment  214  of the body. The channel  212  of the body  200  and the channel  310  of the slide  300  together form a cannula  110 . 
     The holes  412  of the sleeve  400  are generally aligned with the threaded holes  308  at the second end  304  of the sleeve  300 . Thus, the sleeve  400  is attached to the second end of the slide  300  via screws  112 . Moreover, the sleeve  400  partially encases the second end  204  of the body  200  which assists coupling the sleeve  400  and slide  300  to the body  200 . The arms  414  of the sleeve  400  partially extend adjacent to the exterior walls of the fingers  206 . 
     In operation, a user (not shown) grasps the instrument in one hand at the pistol grip  218  and handle  514 . The coupling element  104  having a spine rod resting within or nearby the seat  102  is engaged or gripped between the fingers  206  of the body  200  by applying a small force allowing the fingers  206  to separate slightly and then grasp the coupling element  104  via the groove  105  as shown in FIG.  1 D. The handle  514  is then displaced, moved or squeezed toward the grip  218  in the direction of arrow A as shown in FIGS. 1A and 1B. The displacement of the handle  514  causes the sleeve  400  to advance toward the rod  114  and coupling element  104 . Squeezing the handle  514  angularly displaces the trigger  500  moving the notch  222  of the body  200  out of the locked position from the indentation  510  of the trigger  500 . Thus, with a single continuous squeeze of the handle, the pusher bar  416  contacts the rod  114  at groove  418 . The rod  114  is then advanced into the recess or seat  102  of the coupling element  104  to the position shown in FIG. 1D, while the fingers  206  continue to grip the coupling element  104 . As the slide  300  and sleeve  400  advance, the arms  414  of the sleeve also advance adjacent to the fingers  206 . Thus, the arms  206  prevent the fingers  206  from separating. The user of the instrument may then continuously squeeze the handle to maintain the positioning of the rod  114  on the seat  102  of the coupling element. While the positioning is maintained, the user may use the free hand to perform other tasks. In addition, a fastener  120  (FIG. 1E) may be inserted through the cannula  110  to secure the rod  114  to the coupling element  104 . A driver (not shown) may also be inserted through the cannula to tighten the fastener. Once the rod is secured, the user may release the handle allowing the pusher to withdraw from contact with the rod. Then, the instrument release its grip on the coupling element  104  by slightly rotating the instrument to displace the ratches  211  from the groove  105  of the coupling element and to slightly separate the fingers  206 . A force may then be applied on the instrument in the direction opposite the coupling element. This force will free the instrument from its grip on the coupling element  104 . Thus, the rod  114  is secured to the coupling element  104  as shown in FIG.  1 E. 
     Referring now to FIGS. 6A and 6B, another embodiment of the invention is shown where like elements are similarly numbered. The instrument further comprises a ratchet mechanism  700  and a springing connector  600  connecting the handle  514  and grip  218 . The ratchet mechanism includes a rack  702  having a plurality of female teeth  704 . The rack  702  is connected to the bottom of the pistol grip at hinge  706 . A male tooth  708  extends from the bottom of the handle  514 . 
     The male tooth  708  of the handle cooperates with the female teeth  704  of the rack  702 . FIG. 6A shows the instrument in the beginning or open position so that the male tooth is resting at a first end  710  of the rack  702 . Each of the female teeth of the rack represents a single step. 
     In operation, the user grasps the instrument with one hand via the pistol grip  218  and the handle  514 . After the instrument grips the coupling element via the notches  211  of the fingers, the user then squeezes the handle  214  toward the pistol grip in the direction of arrow B to displace the male tooth  708  one step into the first female tooth. The springing connector  600  causes the handle to lock in this first step, advancing the slide and the sleeve forward the distance of one step. The user repeatedly squeezes the handle to displace the male tooth a single step at a time into each of the female teeth. As this occurs, the slide  300  and sleeve  400  advance forward so that the pusher  416  contacts the rod  114  at groove  418  and urges the rod into position in the seat  102  of the coupling element  104  as illustrated in FIG. 1D at each step. 
     As the ratchet mechanism is operated, the springing connector  600  locks the male tooth. Thus, the user does not have to constantly apply pressure to the handle in order to maintain the position of the rod. Rather, the locking nature of the ratchet maintains the advancement of the slide and sleeve and in turn, the advancement of the rod. Additionally, the user may release his grasp on the instrument without threat of the rod  114  regressing back away from the coupling element  104 , since the ratchet is locked in position. 
     Once again, after the rod  114  is positioned in the seat  102  of the coupling element  104 , a fastener  120  may be inserted through the cannula. A driver may be used through the cannula to tighten the fastener to secure the rod  114  to the coupling element  104 . Once the rod is secured, the rack  702  of the ratchet mechanism may be rotated about the hinge  706  in the direction of arrow C, to unlock the ratchet mechanism. This results in the pusher  416  releasing its contact with the rod  114 . The instrument may then be removed from its grip on the coupling element as discussed above. 
     FIGS. 7A and 7B show yet another embodiment of the invention where like elements are similarly numbered. In this embodiment, the instrument generally comprises a body  200 , slide  300 , sleeve  400 , trigger  500 , springing connector  600  and a ratchet mechanism  700   a.    
     The ratchet mechanism  700   a  includes a plurality a female teeth  704   a  defined in the bottom of the slide  300 . A male tooth  708   a  extends upwards from the body  200 . In addition, a tab  712  extends from the body  200 . The male tooth  708   a  of the body cooperates with the female teeth  704   a  of the slide. 
     FIG. 7A shows the instrument in the beginning or open position so that the male tooth is resting at a front end  710   a  of the plurality of female teeth  704   a . Each of the female teeth  704   a  represents a single step. 
     In operation, the user grasps the instrument with one hand via the pistol grip  218  and the handle  514 . After the instrument grips the coupling element via the notches  211  of the fingers, the user then squeezes the handle  214  toward the pistol grip in the direction of arrow B which displaces the male tooth  708  one step into the first female tooth  704 . The springing connector  600  causes the male tooth to lock in this first step, advancing the slide  300  and the sleeve  400  forward the distance of one step. The user repeatedly squeezes the handle to displace the male tooth a single step at a time and lock into position at each of the female teeth. As this occurs, the slide  300  and sleeve  400  advance forward so that the pusher  416  contacts the rod  114  at groove  418  and urges the rod into position in the seat  102  of the coupling element  104  as illustrated in FIG.  1 D. 
     As the ratchet mechanism is operated, the springing connector  600  locks the male tooth at each step. Thus, the user does not have to constantly apply pressure to the pressure in order to maintain the position of the rod. Rather, the locking nature of the ratchet maintains the advancement of the slide and sleeve and in turn, the advancement of the rod. Additionally, the user may release his grasp on the instrument without threat of the rod  114  regressing back away from the coupling element  104 , since the ratchet is locked in position. 
     Once again, after the rod  114  is positioned in the seat  102  of the coupling element  104 , a fastener  120  may be inserted through the cannula. A driver may be used through the cannula to tighten the fastener to secure the rod  114  to the coupling element  104 . Once the rod is secured, the tab  712  of the ratchet mechanism may be rotated in the direction of arrow D, to unlock the ratchet mechanism. This results in the pusher  416  releasing its contact with the rod  114 . The instrument may then be removed from its grip on the coupling element  104  as discussed above. 
     Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.