Abstract:
Provided is a novel multi-planar taper lock screw for connecting a connecting rod to bone. The screw is capable of multi-directional articulation while the connecting rod position can remain stable and aligned as needed. After the screw had been articulated and properly positioned, it can be locked such that the screw and the connecting rod will remain in relative position to the bone. The screw is configured for easy insertion and connection as well as easy removal and disconnection from the connecting rod. Also provided is a system for fixing two or more bones or bone fragments and a kit for fixing bones or bone fragments. A method of fixing bones or bone fragments is also provided.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to orthopedic surgery, and in particular to devices and prosthesis for stabilizing and fixing the bones and joints of the body. Particularly, the present invention relates to a multi-planar, taper lock screw for securing a spinal rod to a vertebra, wherein the screw can be easily inserted into a vertebra and connect to a spinal rod that can be connected to other vertebrae not on the same plane and can provide a structural configuration that facilitates ease of insertion or removal of the screw as desired. More particularly, the present invention relates to a novel multi-planar, taper lock screw having a proximal flange that is easily accessible to facilitate the connection of a complementarity configured griping tool for improved ease of locking and unlocking of the screw when desired. 
         [0003]    2. Background of the Technology 
         [0004]    It is a common surgical requirement to stabilize and fix bones and bone fragments in a particular spatial relationship to correct the location of skeletal components due to injury or disease. This can be accomplished by using a number of bone pins, anchors, or screws placed in bones across a discontinuity in the bone or bone fragments, such as a fracture, or adjacent vertebrae, or a joint, connected by a rod to maintain a predetermined spatial location of the bones or bone fragments. In some cases the use of these devices may be permanently implanted in the subject. In other cases, the devices may be implanted only as a temporary means of stabilizing or fixing the bones or bone fragments, with subsequent removal when no longer needed. It is also common that device implants that were intended to be permanent may require subsequent procedures or revisions as the dynamics of the subject&#39;s condition warrant. For these reasons, it is desirable that an implanted device be provided, which can be easily locked and unlocked as desired by the surgeon. 
         [0005]    Spinal fixation apparatuses are widely employed in surgical processes for correcting spinal injuries and diseases. These apparatuses commonly employ longitudinal link rods secured to the bone such as vertebrae by spinal bone fixation fasteners such as pedicle screws, hooks and others. 
         [0006]    Many conventional devices for locking a spinal rod to a fixation hook or screw do not offer the needed variability to allow the spinal rod to be easily connected to adjacent vertebrae, which are not aligned on the same plane. Some effort has been made to provide a multi-planar screw; however, even for devices that have attempted to address the issue of securing rods to differently aligned vertebrae, there remains the problem of providing such a multi-planar screw that can also be easily locked and unlocked. 
         [0007]    To meet the problem of securely connecting adjacent vertebrae, not on a common plane a requirement exists to provide a multi-planar, taper lock screw that can be easily inserted and easily removed from the vertebral bone as desired. It is also desirable that such a screw be configured so that it can be locked into position in relation to the bone and the spinal rod without the need to exert any additional torque to the device or force on the patient. Additionally, such a multi-planar screw that can be used without the need for an additional locking piece, such as a set screw or the need to thread a locking device into place would be desirable. 
         [0008]    Conventional efforts to meet this need have fallen short in that no spinal screw has been provided that adapts the spinal rod to the multi-planar environment of the spine while providing a screw head configuration that presents ease of locking and unlocking the rod to the screw. 
         [0009]    Thus a need exists for a multi-planar, taper lock screw that also provides a screw head configuration that is easily grasped by a complementary tool used by an operator for locking and unlocking the rod and screw. 
       SUMMARY OF THE INVENTION 
       [0010]    The multi-planar taper lock screw having a proximal flange provides a novel multi-planar screw for connection of a spinal rod to a first vertebra wherein the head of the screw is easily connected to a rod that can also be connected to an adjacent vertebra not in the same plane as the first vertebra and, due to a novel configuration of the head, can also be easily grasped by an operator using a complementary grasping tool to remove the screw when desired. 
         [0011]    Also provided is a novel multi-planar taper lock screw configured to be easily connected to the vertebra and then connected to a spinal rod without the additional application of torque. 
         [0012]    Also provided is a novel multi-planar taper lock screw configured to have a slidable outer housing over an inner housing containing a spherically configured, pivotable screw head and a removable spinal rod wherein the outer housing can be selectively positioned to fully lock the screw head and the spinal rod in position within the inner housing. 
         [0013]    Also provided is a novel multi-planar taper lock screw configured to have a slidable outer housing over an inner housing containing a spherically configured, pivotable screw head and a removable spinal rod wherein the outer housing can be selectively positioned to fully lock the screw head and the spinal rod in position within the inner housing or can be selectively positioned to lock only the screw head in position while permitting a sliding and rotating motion of the spinal rod about its long axis within the inner housing. 
         [0014]    Also provided is a kit that can include at least two of the novel multi-planar taper lock screws, at least one rod device, and surgical instruments having a configuration complementary to the configuration of the head of the novel screw and configured to facilitate grasping of the screw head for locking and unlocking of the rod. 
         [0015]    Also provided is a method of using the novel multi-planar taper screw wherein the surgical procedure employed, in comparison to conventional methods, is quickly accomplished for locking or unlocking of the device. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, wherein: 
           [0017]      FIG. 1  shows a side view of a surgical rod using the present invention to connect in sequence to three adjacent bone structures of the spine, each bone structure being aligned with a different plane; 
           [0018]      FIG. 2  shows a perspective view of a surgical rod connected to three screws according to the present invention; 
           [0019]      FIG. 3A  shows a side view of the screw according to the present invention, the screw being configured in a closed position; that is with a surgical rod secured and locked in the screw body; 
           [0020]      FIG. 3B  shows a side view of the screw according to the present invention, the screw being configured in an open position, that is with a surgical rod in place within the screw but not secured thereto; 
           [0021]      FIG. 4A  shows a cross-sectional view of the body portion of the screw of the present invention in a closed position, that is with a surgical rod secured and locked in the screw body, 
           [0022]      FIG. 4B  shows a cross-sectional view of the body portion of the screw of the present invention in an open position, that is with a surgical rod in place within the screw body but not secured thereto. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    Detailed embodiments of the present invention are disclosed herein; however, it is understood that the following description is 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 description are non-limiting, but serve merely as a basis for the invention defined by the claims provided herewith. 
         [0024]    As shown in  FIGS. 1-4B , a novel multi-planar tapered lock screw  10  is so configured so as to facilitate ease of insertion of the screw  10  into bone and connection to surgical devices such as spinal rods as well as facilitating easy locking and unlocking as desired.  FIG. 1  illustrates a portion of the lumbar spine with an example of a unilateral orthopedic fixation assembly that includes a connecting rod  12  and three screws  10  according to the present invention. In the example shown, the connecting rod  12  is a spinal rod having a generally circular cross section; however, it is within the concept of the invention to secure connecting rods of any suitable cross-sectional configuration required for the need at hand. 
         [0025]    As best shown in  FIGS. 2 ,  3 A-B, and  4 A-B, the multi-planar tapered locking screw  10  of the present invention includes a screw shaft  14 , which defines an external helical thread  16  for penetrating cancellous bone through the application of torque. The upper portion of the screw shaft  14  terminates in a screw head  18 , that is generally spherical in part and at its uppermost surface  20  defines a screw head recess  22 , which has a recess surface configuration that is complementary to the shape of a tightening and/or loosening tool. Without departing from the concept of the present invention, the screw head recess  22  can also be configured as a protrusion rather than a recess provided that the protrusion has a surface that is complementary for griping attachment to a tool for tightening and/or loosening and provided that the height of the protrusion above the uppermost surface  20  of the screw head  18  is not such that it obstructs or interferes with any of the functions of the screw  10 . 
         [0026]    As best shown in  FIG. 1 , the screw  10  of the present invention is capable of connecting a connecting rod  12  to multiple vertebrae, which are aligned in the spinal column on different planes due to the natural curvature of the spine, by the use of a dual layered screw housing  24  that includes an outer housing  26  and an inner housing  28 . The outer housing  26  is configured such that at least a portion of the inner surface  30  of the outer housing  26  is capable of selectively sliding over a portion of the outer surface  32  of the inner housing  28  in an upward and downward direction along the longitudinal axis of the screw  10 . The configuration of both the outer housing  26  and the inner housing  28  are complementary in that when the outer housing is slid downward in relation to the inner housing at least one outer housing internal compression contact surface  34  is brought to bear against at least a portion of the outer wall  36  of the inner housing  28  and by that compressive force causes the inner housing  28  to in turn to mechanically transmit that compressive force inward toward the central longitudinal axis of the screw  10 . 
         [0027]    A screw head articulation recess  38  is defined in the interior of the lower portion  40  of the inner housing  28 . The interior surface  42  of the articulation recess  38  has a complementary surface configuration to the generally spherical shape of the screw head  18  so as to facilitate multi-planar rotational articulation of the screw head  18  within the recess  38 . The lower most portion of the inner housing  28  defines a screw shaft exit portal  44 , that is sized small enough retain the spherical screw head  18  within the recess  38  but is large enough to allow multi-directional movement of the screw shaft that extends exterior to the inner housing  28 . The recess  38  can include a recess upper edge  46  that is configured to selectively exert a locking compressive force against the screw head  18 . A recess lower edge  48  can also be provided for the same purpose. It is also within the scope of the present invention that all or portions of the interior wall of the recess  38  can selectively provide the compressive force against the screw head  18  that is sufficient to hold the screw head in a locked position. 
         [0028]    The upper portion of the inner housing  28  defines an inner housing connecting rod slot  50  that is sized and configured to permit a connecting rod  12  to be placed transversely within the upper portion of the inner housing  28 . An outer housing connecting rod slot  52  can be provided that is in common alignment with the inner housing connecting rod slot but is not necessarily of exactly the same measurement as the inner housing slot  50 . The inner housing connecting rod slot  50  can define at least one compression contact surface  54  that when forced into compressive contact with a connecting rod  12  present in the slot  50 , the contact surface can serve to securely hold the rod  12  in its relative position to the inner housing  28 . Preferably the inner housing connecting rod slot  50  is provided with an opposing upper compression contact surface  56  and an opposing lower compression contact surface  58 , which together can selectively be forced against the connecting rod  12  so as to secure and releasably lock it in place within the inner housing  28 . 
         [0029]    Preliminary to operation of the screw  10 , the outer housing  26  should be positioned in the open position; that is it should be slid downward relative to the inner housing  28 . The screw shaft  14  can then be driven into the cancellous bone by providing torsional force via a tool configured to mate with and grip the screw head recess  22 . After the screw shaft  14  is positioned within the bone and the driving tool removed from the screw  10 , a connecting rod  12  can be positioned transversely along the common course of and within the inner housing connecting rod slot  50  and the outer housing connecting rod slot  52 . Upon completion of all manipulation of the connecting rod  12  that may be required to articulate the screw head  18  within the inner housing recess  38  and the connecting rod  12  within the inner housing connecting rod slot  50 , the outer housing  26  can be grasped by the operator using a complementarity configured grasping tool that when activated slides the outer housing  26  upward circumferentially over the outer surface of the inner housing  28  from the open or unlocked position to the closed or locked position, as best shown in  FIGS. 3A and 4A . Similarly, the operator can use a complementarity configured unlocking tool to grasp the inner housing  28  and slidably move the outer housing downward along the outer surface of the inner housing  28  from a closed or locked position to an open or unlocked position, as best shown in  FIGS. 3B and 4B . The screw  10  can be provided with an inner housing access slot  60  defined through the wall of the outer housing  26 , which provides access for the unlocking tool that is designed to make grasping contact with an inner housing tool receptor  61  to facilitate quickly unlocking the screw  10  and permit movement of the screw head  18  within the articulation recess  38  and removal of the connecting rod  12  from the inner housing connecting rod slot  50 . The outer housing can be provided with a tool receiving element for the operator&#39;s tool, which is preferably a proximally located annular flange  62  or circumferentially defined annular griping groove  63 , as best shown in  FIGS. 2 ,  3 A-B, and  4 A-B. 
         [0030]    It is within the concept of the invention to selectively position the outer housing  26  along the surface of the inner housing  28  such that the compressive force exerted by the outer housing  26  on the inner housing  28  is such that a partial lock position can be attained; that is, by a limited sliding movement of the outer housing  26 , compressive pressure will be exerted only on the articulation recess and the screw head  18  contained therein while the connecting rod  12  will remain free to slide transversely within the inner housing connecting rod slot  50 . Using this partial lock of the screw  10 , the operator can first position the screw  10  relative to the bone into which the screw shaft  14  has been attached and then manipulate the connecting rod  12  within the screw  10  to optimize its position before sliding the outer housing  26  into a full locked position on the inner housing  28 . 
         [0031]    The materials used to construct the present invention are those which have sufficient strength, resiliency, and biocompatability as is well known in the art for such devices. Methods of manufacture of such surgical implant devices is also well known in the art. 
         [0032]    It is within the concept of the present invention to provide the multi-planar taper lock screw  10  as part of a kit for use in a surgical process, the kit comprising at least two of the screws  10  and at least some of the associated tools for using the screws to connect a surgical rod to adjacent bones or bone fragments. In addition, the kit can contain surgical rods, such as, for example, spinal rods. Additional devices such as cross-connectors or links can also be included in the kit. 
         [0033]    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.