Abstract:
A fluid delivery and bone screw driver apparatus attaches to a bone screw. An inner sleeve joins a material delivery source connected to one end of the inner sleeve to the bone screw connected to the other end. A removable liner communicates the material through the inner sleeve and into the bone screw. An outer sleeve seals the outer sleeve to the head of the bone screw. Rotating the outer sleeve tightens the seal and rotates the bone screw.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 61/277,875, filed Sep. 30, 2009, which is hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    Spinal stabilization procedures typically involve inserting a pedicle screw into the pedicle or pillar of the spine, and then connecting the screw to either plates or rods for stabilization of the lumbar spine for fractures, tumors, and various degenerative conditions. When this procedure is used on osteoporotic patients the pedicle screw is sometimes difficult to fix because the threads of the pedicle screw do not properly secure within the material of the pillar. This is also a problem with non-osteoporotic patients when attempting to secure surgical anchors within the material of other skeletal members. To help achieve proper fixation of screws in osteoporotic skeletal structures, a fenestrated screw is used in conjunction with a cementitious material to provide a better footing for the screw and achieve enhanced bone fixation. 
         [0003]    To achieve this fixation, current techniques often use a driver that is removably attached to the screw and is used to place the screw in a determined location. Once the pedicle screw is in place, the driver is undocked from the screw and a delivery device for the cement is docked to the head of the screw. Percutaneous fenestrated screw procedures are very difficult to perform with current technologies because the process of removing the driver from the screw and attaching a delivery system is often very arduous. 
       SUMMARY 
       [0004]    A fluid delivery and bone screw driver apparatus attaches to a bone screw. The bone screw has a head and shaft. The shaft has a cannula with fenestrations. An exemplary bone screw is disclosed in U.S. patent application Ser. No. 11/736,943, filed Apr. 18, 2007, which is hereby incorporated by reference. 
         [0005]    The apparatus comprises an outer sleeve having a proximal end and a distal end with external threads near the distal end and a grasping surface near the proximal end. And inner shaft having a proximal end and a distal end extends through the outer sleeve. The inner shaft comprises a coupler at the proximal end, a counter-torque bar at the distal end, and a gasket at the distal end. A removable liner extends through the proximal end of the inner shaft and out of the distal end of the inner shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  illustrates a perspective view of a screw driver, a material delivery probe and inner liner. 
           [0007]      FIG. 2  illustrates a partially exploded perspective view of the screw driver and material deliver probe of  FIG. 1 , prior to connection to the pedicle screw. 
           [0008]      FIG. 3  illustrates a cross-section view of  FIG. 1 . taken along line  3 - 3 . 
           [0009]      FIG. 4  illustrates an enlarged view of the distal end of the material delivery probe of  FIG. 1  with counter-torque bar and gasket. 
           [0010]      FIGS. 5   a  and  5   b  illustrate an inner liner that is inserted into the material delivery probe and screw driver of  FIG. 1 . 
           [0011]      FIG. 6  illustrates a perspective view of an exemplary pedicle screw. 
           [0012]      FIG. 7  illustrates a cross section view of pedicle screw of  FIG. 6  taken along line  6 - 6 . 
           [0013]      FIG. 8  illustrates an insertion probe according for use in minimally invasive applications. 
           [0014]      FIGS. 9 through 12  illustrate various other elements. 
           [0015]      FIGS. 13   a  through  13   c  illustrate an insertion probe locked to a pedicle screw with a locking cam.. 
           [0016]      FIGS. 14   a  through  14   c  illustrate a set screw for securing an insertion probe to a pedicle screw. 
           [0017]      FIGS. 15   a  through  15   c  illustrate an inflatable cuff for securing an insertion probe to a pedicle screw. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]      FIG. 1  shows a fluid delivery and bone screw driver apparatus  10 . System  10  includes an inner shaft  15  (also referred to as a material delivery shaft), a screw driver or outer sleeve  20 , and an inner liner  30 . When system  10  is assembled, inner shaft  15  resides at least partially within outer sleeve  20 . Inner shaft  15  and outer sleeve  20  can be secured to a pedicle screw  25 , as will be described below. Inner liner  30  is received inside at least parts of both inner shaft  15  and outer sleeve  20 . 
         [0019]    Referring to  FIGS. 2-4 , inner shaft  15  has a proximal end  14  and a distal end  17 . Proximal end  14  has a coupler, such as a threaded luer lock connection  16 , for connection to a source of cementitious fluid. Distal end  17  has a counter-torque bar  18  and a gasket  19  that is shaped as an o-ring. Inner shaft  15  and outer sleeve  20  are made from stainless steel; however, they may be made from other metallic components having similar functionality. Gasket  19  is made from a non-metal pliable material capable of deforming and providing a seal between relatively moving components. Counter-torque bar  18  can be joined to the shaft by several methods, such as; welding, press-fit, gluing, or any other means known to those skilled in the art. 
         [0020]    Inner shaft  15  has distinct markings or indicia  13  thereon near proximal end  14  that correspond to the position or orientation of fenestrations  33  on pedicle screw  25  shown in  FIG. 2 . Markings  13  serve to indicate to the surgeon the orientation of fenestrations  33  once the screw  25  is inside the body and can be used by a surgeon to align the screw  25  so as to direct cement to a particular location or direct the cement away from vital structures. Markings  13  can be machined, etched (chemical/laser), coated or inked on the inner shaft. 
         [0021]    Referring to  FIGS. 2 ,  3 ,  6  and  7 , outer sleeve  20  has a threaded end  21  and a handle  22 . Threaded end  21  has external threads thereon that are matingly received within threads  28  of pedicle screw  25 . Handle  22  has two opposed ears that are configured for ease of handling and control when a physician is securing outer sleeve  20  to pedicle screw  25  and advancing pedicle screw  25 . Pedicle screw  25  has a head  26  having a slot  29  therethrough. Slot  29  is configured to receive counter-torque bar  18  when inner shaft  15 , outer sleeve  20  and pedicle screw  25  are assembled. 
         [0022]    Referring to  FIGS. 5   a  and  5   b , inner liner  30  is received within inner shaft  15  and outer shaft  20  via luer lock connection  16  during use and is advanced distally through inner shaft  15  into screw  30 . Liner  30  can be made of either metal, non-metal or a combination of both. Referring to  FIG. 5   b , liner  30  has a tapered distal end  31  that permits insertion into cannula  32  of screw  25 . Liner  30  is inserted from 0.3 to 0.5 of the length of screw  25 . Thus, the longer and larger the inner shaft of screw  25 , the further liner  30  is inserted. Liner  30  is substantially inserted into screw  25  so that any reflux of cementitious fluid will stay within liner  30  and not flow through annular opening between pedicle screw  25  and inner shaft  15  past gasket  19 . Liner  30  protects inner shaft  15  and outer sleeve  20  from cementitious fluid that may not stay inside of pedicle screw during fluid delivery. This is of particular concern because the cementitious fluid is often a highly viscous rapidly curing cement. The process of using liner  30  with inner shaft  15  and outer sleeve  20  will be discussed further below. Further, liner  30  is inexpensive disposable element. 
         [0023]    Referring again to FIGS.  2 , 3 , 6  and  7 , cross-section of pedicle screw  25  shows a seat  31 , a cannula  32  and frenestrations  33 . Outer sleeve  20  is able to rotate freely while captured on the inner shaft  15 . When counter-torque bar  18  is received within slot  29 , and gasket  19  is received within seat  31  of pedicle screw  25 , the physician can rotate outer sleeve  20  relative to pedicle screw  25  which action compresses gasket  19  in seat  31 . This compression ensures that a seal is created between gasket  19  distal end of inner shaft  15  and seat  31 . The seal will prevent cementitious fluid from escaping from pedicle screw  25  during fluid delivery. 
         [0024]    System  10  is connected to a fenestrated screw  25  via outer sleeve  20 . Although not required, system  10  can be used with a conventional guidewire to advance system  10  to the desired location to commence procedure. Counter-torque bar  18  is placed in slot  29  and outer sleeve  20  is rotatingly joined to pedicle screw  25  via threads  28 , thereby capturing inner shaft and securing sleeve  20  to pedicle screw  25 . Once the surgeon has placed pedicle screw  25  in the desired location, the surgeon can then remove the guide wire (if one were used). Liner  30  is then inserted into proximal end  14  of inner shaft  15 . After inserting liner  30 , a cement reservoir or delivery tube is then connected to luer lock connection  16 . After cement is delivered to the distal end of the pedicle screw  25 , the entire assembly can be undocked from pedicle screw  25  with no other steps needed to achieve proper fixation. Once the cement has hardened, liner  30  can be removed and discarded, allowing the system  10 , inner shaft  15  and outer sleeve  20  to be detached from pedicle screw  25  and reused. 
         [0025]    Referring to  FIGS. 8 through 12 , system  100  does not use an outer sleeve. In contrast system  100  uses a probe  120  that has a gripping surface  122  to enable a surgeon to firmly grip and manipulate probe  120  during use at proximal end. Distal end of probe  120  has external threads  121  and gasket  119  as disclosed above. Probe  120  also incorporates a threaded luer connection  116  at proximal end to receive liner  30  therein 
         [0026]    Pedicle screw  125  has a rounded head that fits into a cap  126 , such as shown in  FIGS. 11 and 12 . The rounded head enables rotation of pedicle screw  125  inside of cap  126 . Gasket  119  is connected to distal end of probe  120  as shown at  FIG. 8 . Cap  126  is internally threaded to receive external threads  121  of probe  120 . As probe  120  is rotated and advanced distally within cap  126 , gasket  119  is compressed between pedicle screw  125  and probe  120 . 
         [0027]    Not using a torque bar in this embodiment finds use in minimally invasive spinal surgeries due to its small profile. System  100  can also use a liner  30  having the taper in the same way as system  10 , described above. The minimally invasive configuration may not necessarily use a guidewire. 
         [0028]      FIGS. 13   a  and  13   c  show an alternative to the threaded engagement of probe  220  and pedicle screw  225 . Distal end of probe  220  has cam ears  221  that are received inside of recessed track  228  of cap  226 . A ¼ turn locking cam ears  221  to hold cap  226  in place. A sealed connection is formed between gasket  219  and pedicle screw  225  to prevent leakage of cementitious fluid from pedicle screw  225  during delivery. 
         [0029]      FIGS. 14   a  through  14   c  attaches the probe to the screw, wherein a set screw  310 , is used. Set screw  310  having cam ears  315  is inserted into cap  326  along tracks  328 . Set screw  310  uses a ¼ turn locking cam to wedge screw  310  into place. Probe  320  is threadingly received inside of set screw  310  and is advanced distally into pedicle screw  325 . Gasket  319  is received on distal end of probe  320 . Like earlier embodiments, gasket  319  is compressed to ensure a sealed connection between gasket  319  and the seat of pedicle screw. A liner  30  having a taper as described above can be used to prevent any damage to probe  320 . 
         [0030]    Referring to  FIGS. 15 through 15   c,  a further system for securing probe inside of a pedicle screw is shown and generally referenced as system  400 . System  400  includes a probe  420  and a liner  430  (which can be identical to liner  30 ) that are secured to a pedicle screw  425 . System  400  has a sleeve  418  and an inflatable cuff  440 . Sleeve  418  is connected to a pump, syringe, or other fluid source  417  via a tube or port  416  and transports fluid to inflatable cuff  440 . Cuff  440  may be inflated by many substances, such as for example, air, water or saline solution. Cuff  440  is expanded inside of head of pedicle screw  425  to ensure that probe  420  is held securely in place during delivery of cementitions fluid. 
         [0031]    The foregoing description has discussed only a few of the many forms that this invention can take. It is intended that the foregoing detailed description be understood as an illustration of selected forms that the invention can take and not as a definition of the invention. It is only in the claims, including all equivalents, that are intended to define the scope of this invention.