Abstract:
Provided is a dual action surgical instrument for use in orthopedic surgical procedures that is capable of reducing a rod into position in a rod receiving notch in the head of a bone screw with a first action and subsequently locking the rod into the receiving notch by a second action of the same instrument. A method of using the device is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a divisional of U.S. patent application Ser. No. 11/526,880, filed on Sep. 26, 2006, which claims the benefit of and priority to U.S. Provisional Patent Application No. 60/780,596, filed Mar. 9, 2006, the entire contents of which are incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates to orthopedic surgery and in particular to devices for stabilizing and fixing the bones and joints of the body. Particularly, the present invention relates to a dual action instrument capable of reducing a rod into position in a rod receiving notch in the head of a bone screw with a first action and subsequently locking the rod into that receiving notch by a second action of the same instrument. 
     2. Background of Related Art 
     The spinal column is a complex system of bones and connective tissues that provides support for the human body and protection for the spinal cord and nerves. The human spine is comprised of thirty-three vertebrae at birth and twenty-four as a mature adult. Between each pair of vertebrae is an intervertebral disc, which maintains the space between adjacent vertebrae and acts as a cushion under compressive, bending and rotational loads and motions. 
     There are various disorders, diseases and types of injury, which the spinal column may experience in a lifetime. The problems may include but are not limited to scoliosis, kyphosis, excessive lordosis, spondylolisthesis, slipped or ruptured disc, 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. 
     One of the more common solutions to any of the above mentioned conditions involves a surgical procedure known as spinal fusion. A spinal fusion procedure involves fusing two or more vertebral bodies in order to eliminate motion at the intervertebral disc or joint. To achieve this, natural or artificial bone, along with a spacing device, replaces part or all of the intervertebral disc to form a rigid column of bone, which is stabilized by mechanical hardware. 
     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 posteriorly performed, it is common practice to place bone screws into the vertebral bodies and then connect a metal rod between adjacent vertebral bodies. When the spine 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. 
     The process of properly inserting the spinal rod into the receiving slot of a bone screw and then securing that connecting rod in place often can require that the surgeon use a number of instruments and expend a great deal of time and effort to accomplish the task. When bone screws in several adjacent vertebrae are to be securely connected by a spinal rod, the repeated process of inserting the rod into the heads of the one screws and then securing the rod in place for each respective bone screw can be difficult, tiresome and time consuming. It is therefore important that an instrument be provided that is specifically designed to facilitate the process for the surgeon such that the connecting rod can be easily and quickly inserted into each bone screw and with minimal effort and loss of time. It is also desirable that the rod be secured into position in the bone screw head without the application of additional torsional force to the bone screw and the bone into which it is attached. 
     Conventional efforts to meet this need have fallen short in that no single instrument has been provided that effectively positions and inserts a connecting rod into position in the receiving slot of the head of a bone screw and also provides a torque-free locking action to secure the rod in place. 
     For these reasons there remains a need for a device which, can with a single action first securely grasp the head of a bone screw and accomplish the reduction of a posteriorly introduced rod into the head of that bone screw and in a second simple action provide a torque-free locking process of the rod into the bone screw head. 
     SUMMARY 
     In accordance with an embodiment of the present disclosure, there is provided a method of reducing a rod into a taper lock bone screw and locking the rod into place. The method includes providing a rod reducer including an elongate body having a bone screw grasping element, a rod reducing sleeve circumferentially disposed around at least a portion of the elongate body, a rod reducing lever coupled to the rod reducing sleeve, a locking sleeve circumferentially disposed around at least a portion of the rod reducing sleeve, and a locking lever coupled to the locking sleeve. In particular, the rod reducing sleeve includes a rod contact portion. The rod reducing lever is configured to actuate the grasping element to grasp the screw and position the rod into a rod receiving notch in the taper lock bone screw. In addition, the locking sleeve includes a screw grasping structure. The locking lever is configured to actuate the screw grasping structure to grasp an outer sleeve of the taper lock bone screw and move the outer sleeve into a locked position. The method further includes implanting the taper lock bone screw into a bone of a subject, placing the rod in the rod reducer, aligning the rod reducer with the taper lock bone screw, reducing the rod into the rod receiving notch in the taper lock bone screw, and locking the rod into place. 
     In another embodiment, aligning the rod reducer with the taper lock bone screw may include inserting at least a portion of the taper lock bone screw into the rod reducer. 
     In still another embodiment, the rod reducing lever may be pivotally associated with the elongate body and the rod reducing sleeve. 
     In still another embodiment, reducing the rod into the rod receiving notch in the taper lock bone screw may include actuating the rod reducing lever causing grasping element to grasp the taper lock bone screw and rod contact portion to position the rod into the rod receiving notch of the taper lock bone screw. 
     In still another embodiment, actuating the rod reducing lever may include aligning the rod reducing lever with the elongate body. 
     In still another embodiment, locking the rod into place may include actuating the locking lever causing the screw grasping structure to grasp and move the outer sleeve into a lock position. 
     In still another embodiment, actuating the locking lever may include aligning the rod reducing lever with the elongate body. 
     In still another embodiment, the rod reducer may further include a first connecting arm pivotally connecting the rod reducing lever with the rod reducing sleeve. 
     In still another embodiment, the rod reducer may further include a second connecting arm pivotally connecting the locking sleeve with the locking lever. 
     In still another embodiment, the locking sleeve may define a longitudinal slit. 
     In still yet another embodiment, locking the rod into place may include sliding the outer sleeve of the taper lock bone screw into a partially locked position. 
     In accordance with another embodiment of the present disclosure, there is provided a method of reducing a rod into a taper lock bone screw and locking the rod into place. The method includes providing a spinal fixation system including a taper lock bone screw and a rod reducer. In particular, the taper lock bone screw includes an inner housing and an outer housing surrounding at least a portion of the inner housing. The inner housing defines a rod receiving notch, and the outer housing is movable relative to the inner housing. The rod reducer includes an elongate body having a bone screw grasping element, a rod reducing sleeve circumferentially disposed around at least a portion of the elongate body, a rod reducing lever coupled to the rod reducing sleeve, a locking sleeve circumferentially disposed around at least a portion of the rod reducing sleeve, and a locking lever coupled to the locking sleeve. The rod reducing sleeve includes a rod contact portion. The rod reducing lever is configured to actuate the grasping element to grasp the screw and position the rod into the rod receiving notch defined in the taper lock bone screw. In addition, the locking sleeve includes a screw grasping structure. The locking lever is configured to actuate the screw grasping structure to grasp an outer sleeve of the taper lock bone screw and move the outer sleeve into a locked position. 
     The method further includes implanting the taper lock bone screw into a vertebral body of a subject, placing the rod in the rod reducer, aligning the rod reducer with the taper lock bone screw, reducing the rod into the rod receiving notch in the inner housing of the taper lock bone screw, and locking the rod into place. 
     In another embodiment, locking the rod into place may include sliding the outer sleeve of the taper lock bone screw into a partially locked position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features of the disclosed device will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of exemplary embodiments with reference to the accompanying drawings, wherein: 
         FIGS. 1A-B  respectively show a side view and a top view of the dual action rod reducing and locking device in an open position; that is the first actuation lever is in an open position and if activated can effect the bone screw head grasping process and the rod reducing process. The second actuation lever is an open position and if activated can effect the process of locking the rod into position in the bone screw head after the rod has been so positioned. 
         FIGS. 2A-B  respectively show a side view and a top view of the dual action rod reducing and locking device having the first actuation lever in a closed position; that is the first actuation lever is in a closed position and having been moved inward it has effected the bone screw head grasping process and the rod reducing process. The second actuation lever is in an open position and if activated can effect the process of locking the rod into position in the bone screw head after the rod has been so positioned. 
         FIGS. 3A-C  respectively show a side, back, and top view of the dual action rod reducing and locking device in a closed position; that is the first actuation lever is in a closed position and having been moved inward it has effected the bone screw head grasping process and the rod reducing process. The second actuation lever is in a closed position; that is having been moved inward it has effected the process of locking the rod into position in the bone screw head after it had been so positioned. 
         FIG. 4  shows the disassembled dual action rod reducing and locking device from a side perspective. 
         FIGS. 5A-B  respectively show a side view and a cross-sectional view along the longitudinal axis of the dual action rod reducing and locking device in a closed position. 
         FIGS. 6A-D  respectively show a side view, and cross-sectional views along the transverse axis at different levels along the length of the dual action rod reducing and locking device in a closed position. 
         FIGS. 7A-D  respectively show a back view and cross-sectional views along the transverse axis at different levels along the length of the dual action rod reducing and locking device in a closed position. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Detailed embodiments of the present invention are disclosed herein; however, it is understood that the following description and each of the accompanying figures are provided as being exemplary of the invention, which may be embodied in various forms without departing from the scope of the claimed invention. Thus, the specific structural and functional details provided in the following description are nonlimiting, but serve merely as a basis for the invention as defined by the claims provided herewith. The device described below can be modified as needed to conform to further development and improvement of materials without departing from the inventor&#39;s concept of the invention as claimed. 
     The device, as generally shown at  10  in all of the accompanying figures is a dual action rod reducing and locking device that requires only the sequential movement of two separate activation levers on a single instrument to first position a rod into the head of a bone screw and second to lock the rod into place in the head of the bone screw. The device is an elongated multi-layered tubular instrument that includes an elongated central structure  12  about which at certain positions other components of the device  10  are either attached or circumferentially disposed. The central structure  12  can be tubular with a central structure lumen  14  extending from a central structure first end  16  to a central structure second end  18 . The central structure lumen  14  can be sized to permit the passage of other instruments as needed. 
     An upper portion of the central structure  12  that terminates at or near the central structure first end  16  is configured to serve as a handle  20  for the device  10 . The handle  20  of the device extends from a position near the first end  16  to position that approaches toward the central portion of the device  10 . Immediately adjacent to the central structure  12  and circumferentially disposed around at least a portion of the lower part of the central structure  12  is a rod reducing sleeve  22  that is sized and configured to freely move along the longitudinal axis of the device  10 . As with all of the components of the device  10 , the rod reducing sleeve  22  is constructed to be as thin and light weight as possible to facilitate insertion of the device into the surgical site and to promote ease of manual use of the device; however, the structure of the rod reducing sleeve  22  is strong enough to maintain its integrity during the rod reducing process of the device  10  when the rod reducing sleeve  22  will be forced into contact with a rod and must then transfer manual force against the rod so as to position it into a receiving notch in the head of a bone screw. The rod reducing sleeve  22  is sufficiently long so as to extend from a position below the handle  20  of the device  10  to a position at or near the second end  16  of the central structure  12 . 
     A rod reducing actuator  24 , as shown in the exemplary embodiment of  FIGS. 1A-B ,  2 A-B,  3 A-C,  4 ,  5 A, and  6 A, is preferably configured as a lever although other actuating devices can also be used. The rod reducing actuator  24  has a first end  26  that, when in an open position, as shown in  FIGS. 1A-B  can be extended away from or laterally from the device  10  and a rod reducing actuator  24  second end  28 , that is generally more medially directed to the device  10 . Preferably the rod reducing actuator  24  is pivotally attached to the central structure  12  at rod reducer first pivot point  30  provided at a position approximate to the lower portion of the handle  20  of the device  10 . The rod reducer first pivot point  30  of the central structure  12  corresponds to the actuator pivot point  32 , both of which are preferably pivot pin holes that are defined respectively in the central structure  12  and the rod reducing actuator  24  and connected by a pivot pin  34 . It is however, within the inventor&#39;s concept that any pivoting mechanism, such as a dimple and corresponding protrusion, can be used instead of the preferred pivot pin  34 . It is also within the inventors&#39; concept that the rod reducer first pivot point  30  can be positioned anywhere along the length of the central structure  12  as long as effective leverage for the rod reducing actuator  24  can be achieved. 
     As shown in  FIGS. 1A-B ,  2 A,  3 A-C,  4 ,  5 A, and  6 A between the rod reducer first pivot point  32  and the rod reducing actuator second end  28  is a rod reducer second pivot point  36  that is pivotally connected to a first end  38  of a rod reducer connecting arm  40 . As with all pivot points of the device, a pivot pin  34 , as is well known in the art, is preferably used. Approximate to a second end  42  of the rod reducing connecting arm  40  is a rod reducing connecting arm second pivot point  44 , which is pivotally connected to a rod reducing sleeve pivot point  46  located near the upper portion of the rod reducing sleeve  22 . 
     The pivotal connections of the rod reducing actuator  24  to the central structure  12 , the rod reducing connecting arm  40 , and finally to the rod reducing sleeve  22 , as shown in  FIG. 1A  have the effect of pulling the rod reducing sleeve  22  upward along the outside of the central structure  12  when the first end  26  of the rod reducing actuator lever  24  is pulled away or opened away from the longitudinal axis of the central structure  12 . Conversely, as best shown in  FIGS. 2A ,  3 A,  5 A and  6 A, when the rod reducing actuator lever  24  is squeezed by a surgeon so as to close the actuator lever  24  against the handle  20  of the central structure  12  the rod reducing sleeve  22  is forced downward toward the second end  18  of the central structure  12 . 
     As shown in  FIGS. 1A ,  2 A,  3 A,  4 ,  5 A and  6 A, the rod reducing sleeve  22 , at its lowest end near the second end of the central structure  12 , is configured to provide a rod contact point  48  that preferably, as shown in the examples, will have a concave geometry complimentary to the arching shape of a rod cross-section. 
     As shown in  FIG. 4  the second end  18  of the central structure  12  terminates in at least one screw head grasping element  50  that is configured to grasp corresponding structures on the head of the bone screw into which the rod is to be positioned and locked. As shown in  FIG. 4  the central structure diameter is widened or increased just above the grasping elements  50  to form central structure cam surfaces  52  such that as the rod reducing sleeve  22  is moved downward around the outside of the central structure  12 , the inner wall of the rod reducing sleeve  22  can forcibly and compressively contact the cam surfaces  52  of the central structure thus forcing the screw head grasping elements inward into an engaging relationship with a properly positioned screw head. 
     Thus, when the surgeon activates the rod reducing actuator lever  24  by squeezing it inward against the handle  20  of the central structure  12  and the rod reducing sleeve  22  is forced downward, screw head grasping elements  50  engage and hold the screw head in place while the rod reducing sleeve and its terminal rod contacting point make forcible contact with a properly positioned rod such that as the screw head is held stationary, the rod is forced downward into position with a rod receiving notch of that screw head. A screw head having a rod receiving notch as well as appropriately configured corresponding grasping element receiving structures on the head of the bone screw is disclosed in commonly assigned U.S. patent application Ser. Nos. 11/493,624 and 11/493,625, the complete disclosures of which are fully incorporated herein by reference. 
     Upon completing the first action of the dual action device  10 , that of grasping the screw head and reducing the rod into position in the screw head, the surgeon can then initiate the second action of the device, that of locking the rod in position in the screw head. 
     To accomplish this second action, the device  10  is provided with a locking sleeve  54  that is circumferentially disposed around at least a portion of the rod reducing sleeve  22 . The locking sleeve  54  is sized to freely moved upward or downward along the longitudinal axis of the device  10 . The locking sleeve has a locking sleeve first end  56  approximately at the level of the upper portion of the rod reducing sleeve and a locking sleeve second end  58  approximately at the level of the central structure second end  18 . 
     A locking actuator,  60 , which is preferably in the form of a lever actuator as shown in  FIGS. 1A-B ,  2 A-B,  3 A-B,  4 ,  5 A-B,  6 A and  7 A, can be provided and pivotally attached to the opposite side of the central structure  12  from the rod reducing actuator  24 . The locking actuator  60  can have a locking actuator first end  62  that when in the open position as shown in  FIGS. 1A-B  is located away from or lateral from the central structure  12  and a locking actuator second end  64  that is located more medial to the central structure  12 . The locking actuator  60  is pivotally attached to the central structure  12  at a locking actuator first pivot point  66  that is at or near the second end of the locking actuator  60 . At a position between the first pivot point  66  and the locking actuator first end  62 , the locking actuator  60  is provided with a second pivot point  68  that is pivotally attached to a locking actuator connecting arm  70  at a locking connecting arm first pivot point  72 . The locking connecting arm  70  has a locking connecting arm first end  74  and a locking connecting arm second end  76 . At or near the locking actuator second end  76  is a connecting arm second pivot point  78 . Pivotally connected to the locking actuator connecting arm  70  at the second pivot point  78  is upper portion of the locking sleeve  54 . 
     The pivotal connections disclosed above for the locking actuator  60  to the locking actuator connecting arm  70  and finally to the locking sleeve  54  are such that when a surgeon squeezes the locking actuator lever  60  inward to a closed position adjacent to the handle  20 , as shown in  FIGS. 3A-B ,  5 A-B,  6 A and  7 A, the activation force is transmitted to the locking sleeve  54  so as to pull it upward along the outside of the rod reducing sleeve  22 . 
     The locking sleeve  54  is provided with at least one expansion slit  80  that extends from the locking sleeve second end  58  upward along the longitudinal axis of the device for a portion of the total length of the locking sleeve  54 . The second end of the locking sleeve  54  is configured to slip fit over the external surface of a bone screw head and to engage complimentary structures on the bone screw head such that when the locking actuator  60  is squeezed inward to a closed position and the locking sleeve  54  is pulled upward, the inward bias of the locking sleeve  54  will maintain an inward holding pressure on the outer sleeve of the bone screw head and in doing so pull the outer sleeve of the taper lock bone screw upward while the rod reducing sleeve  22  holds the inner portion of the taper lock bone screw in place. The effect of this holding and pulling action caused by the squeezing of the locking actuator lever  60  is that the outer sleeve of the taper lock screw will produce compressive forces against the rod contained within the head of the taper lock screw and it will thereby be locked into position. 
     It is the inventors&#39; understanding that a partial squeezing movement of the locking actuator lever  60  will result in a partial compressive force on the taper lock screw and as such can provide a partial lock position that can allow for some adjustment of the relative position of the rod and screw one to the other. After any such adjustment is made, the locking actuator  60  can be moved fully inward into a closed or fully locked position. Upon completion of the second action of locking the rod into position, the device  10  can be released from its grasp of the screw and removed from the surgical site. When used, the partial lock position can be identified by the surgeon by providing a visual cue or indicia on the locking actuator lever  60  or by providing tactile or audible feedback to the user as the locking actuator  60  moves the mechanism past a cam or other frictional contact provided within the mechanism 
     The device  10  can be manufactured as integral components by methods known in the art, to include, for example, molding, casting, forming or extruding, and machining processes. The components can be manufactured using materials having sufficient strength, resiliency and biocompatibility as is well known in the art for such devices. By way of example only, suitable materials cam include implant grade metallic materials, such as titanium, cobalt chromium alloys, stainless steel, or other suitable materials for this purpose. 
     It is also within the concept of the present invention to provide a kit, which includes the dual action device disclosed herein. Additionally, a kit can include two or more screws adaptable for use with the disclosed device, such as the taper lock screw disclosed and claimed in the commonly assigned and fully incorporated U.S. patent application Ser. Nos. 11/493,624 and 11/493,625. In addition the kit can contain surgical rods, such as, for example spinal rods. Additional devices such as cross-connectors, hooks, or links can also be included in the kit. Such a kit can be provided with sterile packaging to facilitate opening and immediate use in an operating room. 
     Each of the embodiments described above are provided for illustrative purposes only and it is within the concept of the present invention to include modifications and varying configurations without departing from the scope of the invention that is limited only by the claims included herewith.