Abstract:
A surgical screw system comprising a cannulated screw, a guide wire and a driver. The screw has a head, a tubular body with a bore, and a tip opposite the head. The guide wire, shorter than the screw, is slidably disposed within the bore of the screw. The guide wire has a working end deployable beyond the tip of the screw, and the working end is sharpened to penetrate the bone and produce a pilot hole when an axial force is applied. The guide wire extends to deploy the working end beyond the tip to create the pilot hole, and fully retracts into the screw upon installation of the screw. The driver passes through the head of the screw into the bore, and applies the axial force to the guide wire. The driver may be used to drive the screw into the bone, and is removable from the screw.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the priority date of U.S. Provisional Patent Application Ser. No. 62/183,371, titled, Retractable Screw Guide, filed Jun. 23, 2015. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Field of the Invention 
         [0003]    This invention relates to the field of orthopedic fixation devices, and more specifically, to retractable devices for establishing a desirable angle for screws used in orthopedic devices. 
         [0004]    Description of the Related Art 
         [0005]    A variety of screws are employed in connection with orthopedic surgical techniques and devices. For example, in many spinal surgeries pedicle screws are used to fix spinal implant devices by insertion of the screws into the left and right pedicles of the vertebrae. The pedicle screws can be used as anchors for rods or other connectors, for example, in spinal fusion applications. Pedicle screws can also be used to fix spinal devices such as stand-alone cervical cages directly in the disc space. Regardless of the application, it is important for the pedicle screws to be inserted at the proper angle. Similarly, other orthopedic screws require proper insertion angles for ideal fixation. 
       SUMMARY OF THE INVENTION 
       [0006]    In one or more embodiments, a system is disclosed including a cannulated screw and guide wire, wherein the guide wire is retractable into the screw at, during or after the inception of contact of the screw with bone for deployment of the screw. In another embodiment, a cannulated screw is disclosed having an integral retractable guide wire. 
         [0007]    Currently, simple cannulated screws are typically inserted over a separately placed guide wire that is not attached to the screw. In using such devices, the user must first place the guide wire into position and then place the screw over the guide wire. Such guide wires can inadvertently be advanced, retracted or otherwise moved during placement of the screw, or become bent or kinked. In addition, after placement, guide wires may present obstacles to work around, especially when more than one guide wire is used simultaneously in a confined space. 
         [0008]    Moreover, guide wires by themselves cannot be used to establish a desirable screw insertion angle. Known guide wires merely guide a screw to a starting position, and subsequent insertion at a desired angle depends solely on the ability of the user. 
         [0009]    In some instances, insertion of an orthopedic screw along a desired path or angle is not easily achievable. For example, in stand-alone cervical cages, due to the small size of the working area, it is difficult to attain a screw trajectory that will engage the mid/post vertebral body. 
         [0010]    Retractable screw guides as disclosed herein may be inserted as a unitary device whereby the guide wire and screw travel together. The cannulated screw is collinear with the guide wire contained in a bore of the screw, preventing bending or kinking of the guide wire. The guide wire retracts into the screw preventing inadvertent advancement of the guide wire. This markedly facilitates more efficient placement of the screw. 
         [0011]    Clinical uses of the retractable screw guides include percutaneous pedicle screws, fixation screws, etc. for stand-alone cages such as cervical stand-alone cages, orthopedic or spinal fixation and fracture fixation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    For the purposes of illustration, there are forms shown in the drawings that are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
           [0013]      FIG. 1  is a perspective view of a device having a cannulated screw with a guide wire disposed therein according to an embodiment of the present disclosure; 
           [0014]      FIG. 2  is a cross-sectional view of an embodiment of an end of the device of  FIG. 1  taken along line A-A′; 
           [0015]      FIG. 3  is a cross-sectional view of the device according to  FIG. 1  taken along line A-A′ with a guide wire retracted within the screw according to an embodiment of the present disclosure; 
           [0016]      FIG. 4  is a cross-sectional view of the device according to  FIG. 1  taken along line A-A′ with a guide wire extended from the screw according to an embodiment of the present disclosure; 
           [0017]      FIG. 5  is a cross-sectional view of a bore of a cannulated screw with a guide wire retracted within the bore according to an embodiment of the present disclosure; 
           [0018]      FIG. 6  is a cross-sectional view of a bore of a cannulated screw with a guide wire extended from the opening of the bore according to an embodiment of the present disclosure; and 
           [0019]      FIG. 7  is a view of a device in accordance with one or more embodiments partially engaged to a cervical vertebra through a cervical cage. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0020]    The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. In the drawings, the relative sizes of regions or features may be exaggerated for clarity. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0021]    It will be understood that when an element is referred to as being “coupled” or “connected” to another element, it can be directly coupled or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly coupled” or “directly connected” to another element, there are no intervening elements present. Like numbers refer to like elements throughout. As used herein the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0022]    In addition, spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. Thus, the exemplary term “under” can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
         [0023]    Well-known functions or constructions may not be described in detail for brevity and/or clarity. 
         [0024]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0025]    Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Unless otherwise indicated or defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. The terminology used herein is for describing particular embodiments only and is not intended to be limiting. 
         [0026]    Embodiments of the present invention are described with reference to the figures. Now referring to  FIGS. 1-3 , a device  2  includes a cannulated screw  10  and a guide wire  50 . The screw  10  includes a head  12 , a bore  14  and an opening  16  distal of the head  12 . The screw  10  also has a thread-starting tip  18  which tapers to a smaller diameter than the main body, to facilitate engagement of the screw  10  into the bone. The bore  14  is in communication with the opening  16  of the screw  10 . A driver  70  extends through the bore  14  in the head  12  and away from the screw  10  in a direction opposite the tip  18 . The driver  70  butts up against a top end of the guide wire  50 . The driver  70  is used by a user/surgeon to drive the guide wire  50  out the tip  18  of the screw  10 , creating a pilot hole in the target bone. As will be discussed below, the guide wire  50  can be manipulated to create the pilot hole with an orientation and angle which is desired by the surgeon for installation of the screw. 
         [0027]    With reference to  FIGS. 2 and 5 , the screw opening  16  may include a conical chamfer to provide space for movement of the guide wire relative to the screw  10 . The screw  10  may be any surgical screw such as but not limited to percutaneous surgical screws, fixation screws, screws used in connection with stand-alone cages, fracture fixation screws and the like. In one embodiment the screw  10  is a fixation screw having a bore  14  for a cervical stand-alone cage. 
         [0028]    The guide wire  50  includes a working end  52 . The working end  52  is operable to produce a pilot hole when pressure is applied along the long axis of the guide wire  50  in the direction of the working end  52 . In one or more embodiments the working end  52  is awl- or spike-tipped. The guide wire  50  may have a diameter that is near the diameter of the bore  14  to provide a close, slidable fit therein. In other embodiments the guide wire  50  may have a diameter anywhere from 15 to 85% of the diameter of the bore  14 . 
         [0029]    The driver  70  includes a stop  60 . The stop  60  limits the travel of the driver  70  into the screw  10 , and thus prevents advancement of the guide wire  50  beyond a selected point. The stop  60  may be integral with the guide wire  50  or may be removably connectable. For example, the stop  60  may be a grommet of a resilient material such as rubber, the grommet having a central bore for receiving the guide wire  50 . The grommet may for example be frictionally engaged to the guide wire  50  such that manual pressure can result in the advancement of the grommet along the guide wire, while the frictional engagement resists movement when force is not applied thereto. In another example, the stop  60  may be a freely slidable element, such as a disc having a central bore formed therein which is slidably engageable with the guide wire  50 , the disc having a set screw to permit fixation of the stop  60  in a desired location along the guide wire  50 . In other embodiments the stop  60  is not moveable. The distance the guide wire  50  may be advanced beyond the opening  16  of the screw  10  before the stop  60  on the driver  70  contacts the head  12  is a matter of design choice. 
         [0030]    The driver  70  may also include a handle at the end opposite the screw  10 , where the handle provides a better grip on the driver  70  by the user/surgeon. 
         [0031]    The guide wire  50  is retractably disposed within the bore  14  of the screw  10 . The guide wire  50  has a length which is less than the length of the screw  10 , such that the guide wire  50  can be fully retracted into and contained within the body of the screw  10 , both before deployment of the guide wire to create the pilot hole and after creation of the pilot hole. After the guide wire  50  is extended out the tip  18  of the screw  10  to create the pilot hole in the bone, the guide wire  50  is retracted back into the body of the screw  10  (either retracted by pulling back into the screw  10 , or retracted by virtue of the advancement of the screw  10  into the pilot hole) and remains there after completion of the surgical procedure. 
         [0032]    Now referring to  FIGS. 5 and 6 , the working end  52  of the guide wire  50  may be curved. The curvature of the working end  52  is such that a tip angle  54  is created, where the tip angle  54  is the angle between a tangent at the working end  52  and the straight main body portion of the guide wire  50 . Different models of the guide wire  50  can be made readily available to the user/surgeon, who can select the guide wire  50  having the tip angle  54  which is needed for the particular patient&#39;s application. The tip angle  54  may preferably be in a range of 10-20°, but may be as high as 30°. Of course, the tip angle  54  is zero in straight models of the guide wire  50 , as shown in  FIGS. 2-4 . 
         [0033]    In use, the device  2  is initially deployed with the guide wire  50  inside the screw  10 , and the driver  70  extending out of the head  12  in the direction of the user/surgeon. The screw  10  is advanced to the desired location at which the screw  10  is to be fixed to the patient. Pressure is applied to the guide wire  50  via the driver  70  such that the working end  52  drives into the bone to create the pilot hole. In the curved-tip embodiment of  FIGS. 5-6 , the driver  70  can be used to rotate the guide wire  50  within the bore  14  of the screw  10  so that the guide wire  50  creates the pilot hole at the angle desired by the surgeon. Establishing the position and orientation of the guide wire may be assisted by real-time images during surgery, such as ultrasound, MRI, etc. 
         [0034]      FIG. 7  depicts a cervical cage  100  disposed between adjacent vertebrae  200 ,  202 . As discussed above, the angle of the pilot hole in the bone is determined by the user/surgeon, who can rotate the guide wire  50  in the bore  14  of the screw  10  prior to application of bone-penetrating pressure. Thus, a user can manipulate the device  2  so that the guide wire  50  is disposed through an opening formed for example in a ventral wall of the cervical cage  100  and apply force so that a pilot hole is established for example in the vertebra  200  at the desired angle for inserting the screw  10  in the bone  200 . Once the pilot hole is established, the screw  10  can be advanced along the guide wire  50  and screwed into the pilot hole and the guide wire  50  can either be manually retracted, or is retracted by virtue of the advancement of the screw  10  into the bone  200  by the user. The ability to select a tip angle  54  as desired, and rotate the guide wire  50  to the desired orientation within the screw  10 , gives the user complete flexibility in creating the pilot hole in the bone  200  at exactly the angle which is called for in the individual patient. 
         [0035]    The screw  10  can be driven via external or internal driving mechanisms. Referring again to  FIG. 1 , the head  12  in this embodiment has an external hexagonal shape like a typical bolt head. When the pilot hole has been created in the bone by the working end  52  of the guide wire  50 , and the screw  10  is ready to be driven into the bone, the driver  70  is removed from the screw  10  and a wrench-type device is used to rotate the screw  10  and drive the threads into the bone. The wrench-type device may be adapted to not only engage the hex head  12  of the screw  10  for torque, but also to apply axial force to the screw  10  to ensure positive engagement of the screw threads in the bone. 
         [0036]    In another or overlapping embodiment, an internal driving feature is also provided in the screw  10 . For example, an internal hex drive (or square, or star, or any such drive tool shape) can be included in the bore  14  inside the head  12 . In this way, the external hex head  12  can be used to start the screwing of the screw  10  into the bone, then the driver  70  can be removed from the screw  10  and a hex key can be used in the internal hex pattern inside the bore  14  to drive the screw  10  fully into position. Alternately, the guide wire  50  can be removed from the screw  10  before the screw  10  is driven into the bone, and the hex key and internal hex feature can solely be used to drive the screw  10  into the bone. 
         [0037]    In yet another embodiment, the driver  70  may be adapted to drive the screw  10  into the bone via the internal driving feature of the head  12  discussed above. For example, some or all of the driver  70  may have a cross-sectional shape matching the internal driving feature of the screw  10 , such as a hex-shaped driver (“Allen wrench”). In this embodiment, the driver  70  is first used to position the screw  10  at the desired location and push the guide wire  50  out of the screw  10  to create the pilot hole. Then, the driver  70  is rotated like a screwdriver, with the hex-drive shape of the driver  70  causing the screw  10  to thread into the pilot hole in the bone. When the screw  10  is fully driven into the bone, the guide wire  50  has completely retracted into the screw  10 , and the driver  70  may be removed from the head  12  of the screw  10 , thus completing the installation. 
         [0038]    Although the devices and systems of the present disclosure have been described with reference to exemplary embodiments thereof, the present disclosure is not limited thereby. Indeed, the exemplary embodiments are implementations of the disclosed systems and methods are provided for illustrative and non-limitative purposes. Changes, modifications, enhancements and/or refinements to the disclosed systems and methods may be made without departing from the spirit or scope of the present disclosure. Accordingly, such changes, modifications, enhancements and/or refinements are encompassed within the scope of the present invention.