Abstract:
Biomedical implant fastener systems, such as bone screw systems and the like. In some embodiments, a fastener may comprise a first plurality of teeth, and a washer configured to be received on the fastener may comprise a second plurality of teeth configured to be engaged with the first plurality of teeth. The first plurality of teeth may be configured to engage with the second plurality of teeth such that so as to allow for selective rotation between the washer and the fastener in a first rotational direction and so as to prevent rotation between the washer and the fastener in a second rotational direction opposite from the first rotational direction when the fastener is engaged with the washer such that second plurality of teeth is engaged with the first plurality of teeth so as to prevent the fastener from backing out of the washer after engagement.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/579,667, filed on Oct. 15, 2009 and titled “INTERLOCKING BONE SCREW AND WASHER CONCEPTS,” which claims the benefit of priority of U.S. Provisional Patent Application No. 61/105,545, filed on Oct. 15, 2008 and titled “INTERLOCKING BONE SCREW AND WASHER CONCEPTS,” the entire contents both of which are hereby incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to a surgically-implantable spinal or other anatomical assembly. More specifically, in some embodiments, the present invention relates to a biomedical implant fastener system, such as a cannulated bone screw system. 
       BACKGROUND OF THE INVENTION 
       [0003]    In various cases, it is desirable to immobilize a facet joint of the spine (e.g. in support of a spinal fusion, etc.) by means other than conventional pedicle screw systems. A variety of surgically-implantable devices and assemblies have been developed in order to address such cases. Typically, these devices and assemblies utilize a single transfacet bolt or the like that is disposed through a bore drilled through the superior and inferior facets of the facet joint. However, not all spinal morphologies support the utilization of such a transfacet bolt, and the utilization of such a transfacet bolt can be clumsy depending upon the application. In such cases, the use of an alternative device or assembly is desirable. However, no such alternative devices or assemblies are currently available or in existence. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    In an exemplary embodiment of the present invention, a cannulated bone screw system includes a screw with a threaded portion, a non-threaded portion, and a first plurality of teeth spaced apart from a screw head; and a washer with an interior portion with a second plurality of teeth and an opening and an outer portion with a plurality of spikes. The first plurality of teeth are on an inferior convex surface; wherein the second plurality of teeth are on a superior concave surface; and wherein the first plurality of teeth and the second plurality of teeth are operable to mate to prevent the screw from backing out of the washer while allowing the cannulated bone screw system to conform/pivot in order to accommodate different bone morphologies. The screw head can include keyed flanged heads. The cannulated bone screw system can further include a screw holder operable to engage the keyed flanged heads. Optionally, the cannulated bone screw system further includes a screw holder assembly disposed to the screw holder. Alternatively, the cannulated bone screw system further includes a rescue screw assembly disposed to the screw holder. The plurality of spikes are operable to engage a bone. The screw can be driven into the washer positioned at a pilot hole in a bone at an angle. Optionally, the bone includes a first facet joint and a second facet joint; wherein the pilot hole is located on the first facet joint; wherein the plurality of spikes are engaged to the first facet joint; and wherein the threaded portion is positioned within the second facet joint. The cannulated bone screw system can further include a drill guide and washer holder comprising an end clasping mechanism. Optionally, the end clasping mechanism includes an inserter tube that contains the washer. 
         [0005]    In another exemplary embodiment of the present invention, a cannulated bone screw system includes a screw with a threaded portion, a non-threaded portion, and a first plurality of teeth spaced apart from a screw head; and a washer with an interior portion with a second plurality of teeth and an opening and an outer portion with a plurality of spikes; wherein the second plurality of teeth are on a superior concave surface; and wherein the first plurality of teeth and the second plurality of teeth are operable to mate to prevent the screw from backing out of the washer while allowing the cannulated bone screw system to conform/pivot in order to accommodate different bone morphologies. The cannulated bone screw system can further include means for holding the screw, means for positioning the washer, means for drilling a pilot hole, and means for inserting the screw into the pilot hole. 
         [0006]    In yet another exemplary embodiment of the present invention, a method of screwing a cannulated bone screw into a bone includes positioning a washer on the bone; drilling a pilot hole; engaging a cannulated bone screw; positioning the cannulated bone screw at the pilot hole; screwing the cannulated bone screw into the pilot hole; engaging the cannulated bone screw to the washer; and applying rotational force to drive a plurality of spikes on the washer into the bone. The cannulated bone screw can include a first plurality of teeth spaced apart from a screw head; and the washer can include an interior portion with a second plurality of teeth and an opening and an outer portion with the plurality of spikes. The first plurality of teeth are on an inferior convex surface; wherein the second plurality of teeth are on a superior concave surface; and wherein the first plurality of teeth and the second plurality of teeth are operable to mate to prevent the screw from backing out of the washer while allowing the cannulated bone screw system to conform/pivot in order to accommodate different bone morphologies. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present invention is illustrated and described herein with reference to the various drawings, m which like reference numbers denote like system components/method steps, as appropriate, and in which: 
           [0008]      FIG. 1  illustrates different views of a cannulated bone screw according to an exemplary embodiment of the present invention; 
           [0009]      FIG. 2  illustrates a close up view of the radial interlocking convex toothed surface and the screw head of the cannulated bone screw of  FIG. 1  according to an exemplary embodiment of the present invention; 
           [0010]      FIG. 3  illustrates different views of a washer for mating with the cannulated bone screw of  FIG. 1  according to an exemplary embodiment of the present invention; 
           [0011]      FIG. 4  illustrates the cannulated bone screw of  FIG. 1  engaged with the washer of  FIG. 3  according to an exemplary embodiment of the present invention; 
           [0012]      FIG. 5  illustrates a screw holder for engaging the screw head of the cannulated bone screw of  FIG. 1  according to an exemplary embodiment of the present invention; 
           [0013]      FIG. 6  illustrates a bone screw and screw holder assembly according to an exemplary embodiment of the present invention; 
           [0014]      FIG. 7  illustrates a rescue screw system assembly for removing the cannulated bone screw of  FIG. 1  according to an exemplary embodiment of the present invention; 
           [0015]      FIG. 8  illustrates a cannulated bone screw and a washer according to another exemplary embodiment of the present invention; 
           [0016]      FIG. 9  illustrates the cannulated bone screw engaged with the washer according to an exemplary embodiment of the present invention; 
           [0017]      FIG. 10  illustrates a drill guide and washer holder according to an exemplary embodiment of the present invention; 
           [0018]      FIG. 11  illustrates different views of a cannulated drill according to an exemplary embodiment of the present invention; 
           [0019]      FIG. 12  illustrates different views of a screw holder assembly  1200  and a screw holder for the cannulated bone screw of  FIG. 8  according to an exemplary embodiment of the present invention; 
           [0020]      FIG. 13  illustrates a screw driver with a hexalobular design according to an exemplary embodiment of the present invention; 
           [0021]      FIG. 14  illustrates a rescue screw system according to an exemplary embodiment of the present invention; and 
           [0022]      FIG. 15  illustrates different views of the rescue screw system of  FIG. 14  according to an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    Referring to  FIG. 1 , different views are illustrated of a cannulated bone screw  100  according to an exemplary embodiment of the present invention. The cannulated bone screw  100  includes a threaded end portion  102 , a non-threaded portion  104 , and a radial interlocking convex toothed surface  106  disposed near a screw head  108 . The threaded end portion  102  is operable to screw into a bone, such as a facet joint or the like. The cannulated bone screw  100  can be utilized to stabilize facet joints through an angular insertion of the cannulated bone screw  100  into a first facet and screwing the cannulated bone screw  100  into a second facet, the associated pedicle, or any other bony structure. Once fully engaged between the facets, the associated pedicle, or any other bony structure, the threaded portion  102  is embedded in the second facet, the associated pedicle, or any other bony structure, and the non-threaded portion  104  is in the first facet. Additionally, a washer ( FIG. 3 ) is operable to engage the screw head  108  and an outer surface of the first facet. It should be noted that any suitable guide holes or bores can be utilized in achieving the placement/securement of the cannulated bone screw  100 . 
         [0024]    Referring to  FIG. 2 , a close up view illustrates the radial interlocking convex toothed surface  106  and the screw head  108  of the cannulated bone screw  100  according to an exemplary embodiment of the present invention. The screw head  108  includes a unique slotted head flange that holds and drives the cannulated bone screw  100  into a facet joint or the like. The unique head flange design holds bone screw  100  securely as well as permitting initial thread engagement into a pilot hole. The radial interlocking convex toothed surface  106  includes a radial toothed pattern on an inferior convex surface that is configured to mate with a superior concave surface of a washer, as depicted in  FIG. 3 . Any suitable radial toothed pattern and mating superior concave surface can be utilized, as long as relative rotational between the two structures is selectively prevented upon engagement. 
         [0025]    Referring to  FIG. 3 , different views are illustrated of a washer  300  for mating with the cannulated bone screw  100  according to an exemplary embodiment of the present invention. The washer  300  includes a concentric shape dimensioned responsive to the cannulated bone screw  100 . The washer  300  includes an opening  302  for receiving the threaded end portion  102  and the non-threaded portion  104  of the cannulated bone screw  100 . An interior of the washer  300  includes an interlocking radial toothed pattern on a superior concave surface  304 . The superior concave surface  304  is configured to mate with the inferior convex surface on the radial interlocking convex toothed surface  106 . The interlocking teeth between the washer  300  and the screw head  108  advantageously prevent rotational loosening of the cannulated bone screw  100 . A bottom portion  310  of the washer  300  includes a plurality of spikes  312 . The plurality of spikes  312  are configured to engage a bone when the cannulated bone screw  100  and the washer  300  are screwed into the bone. It should be noted that, throughout, spikes can be replaced with any suitable frictional surface for preventing movement and/or rotation. 
         [0026]    Referring to  FIG. 4 , the cannulated bone screw  100  is illustrated engaged with the washer  300  according to an exemplary embodiment of the present invention. The opening  302  of the washer  300  is slid over the threaded portion  102  to the non-threaded portion  104 . As the threaded portion  102  is screwed into a bone, the spikes  312  on the washer  300  engage the bone, and the washer  300  engages the radial interlocking convex toothed surface  106  on the cannulated bone screw  100 . In the locked position, the interlocking concave/convex surfaces on the toothed surface  106  and the washer  300  prevent the screw from backing out while allowing the cannulated bone screw  100  to conform/pivot in order to accommodate different bone morphologies. 
         [0027]    Referring to  FIG. 5 , a screw holder  500  is illustrated for engaging the screw head  108  according to an exemplary embodiment of the present invention.  FIG. 5  illustrates the screw holder  500  disengaged from and engaged to the screw head  108 . The screw holder  500  is configured to snap over keyed head flanges  502  in the screw head  108 . The screw holder  500  includes a first arc member  510  and a second arc member  512 , each configured to engage one of the keyed head flanges  502  in the screw head  108 . The arc members  510 ,  512  each include a notch  514  which snaps on the keyed head flanges  502 , and a top of the arc members  510 ,  512  substantially mates with a top side  520  of the toothed surface  106 . The screw holder  500  further includes a first arc portion  522  and a second arc portion  524  offset from the arc members  510 ,  512 . The arc portions  522 ,  524  are operable to engage a top  526  of the screw head  108  when the arc members  510 ,  512  are engaged to the keyed head flanges  502 . Collectively, the arc members  510 ,  512  and the arc portions  522 ,  524  define notches  526  which are operable to engage the keyed head flanges  502 . In the engaged position, the screw holder  500  is operable to translate a rotational force to the cannulated bone screw  100  to enable engagement of the washer  300  and a bone. The screw holder  500  also further includes a first support member  530  and a second support member  532 . Each of the support members  530 ,  532  are disposed to the arc members  510 ,  512 , and the arc portions  522 ,  524  extend from the support members  530 ,  532 . 
         [0028]    Referring to  FIG. 6 , a bone screw and screw holder assembly  600  is illustrated according to an exemplary embodiment of the present invention. The bone screw and screw holder assembly  600  is operable to engage the screw holder  500  and the cannulated bone screw  100  for insertion into a bone. The support members  530 ,  532  of the screw holder  500  are each disposed to a cylinder section  540 . The cylinder section  540  engages a coupling mechanism  602  which enables the bone screw and screw holder assembly  600  to engage the screw holder  500 . Note, the coupling mechanism  602  can be disposed on the screw holder  500 , on the bone screw and screw holder assembly  600 , or separate from both. The coupling mechanism  602  is configured to provide engagement between the screw holder  500  and the bone screw and screw holder assembly  600 . A cylinder portion  604  of the bone screw and screw holder assembly  600  extends from the coupling mechanism  602  to a handle portion  606 . The handle portion  606  can include a T-shaped handle  608  and a grip portion  610 . In operation, a surgeon utilizes the bone screw and screw holder assembly  600  to engage the screw holder  500  and the cannulated bone screw  100 . The handle portion  606  enables the surgeon to insert the threaded portion  102  and the non-threaded portion  104  into a bone. 
         [0029]    Referring to  FIG. 7 , a rescue screw system assembly  700  is illustrated for removing the cannulated bone screw  100  according to an exemplary embodiment of the present invention. The rescue screw system assembly  700  engages the cannulated bone screw  100  in a similar fashion as the screw holder  500  as described in  FIG. 5 . The rescue screw system assembly  700  includes a cylinder member  702  disposed to an engagement mechanism  704  at one end. The engagement mechanism  704  is configured to engage the cannulated bone screw  100 . A grip portion  706  is disposed at another end of the cylinder member  702 . A handle portion  708  is disposed to the grip portion  706 . Collectively, a surgeon can utilize the grip portion  706  and the handle portion  708  to maneuver the rescue screw system assembly  700  to engage the cannulated bone screw  100 , and to subsequently remove the cannulated bone screw  100  through rotational force imposed through the grip portion  706  and the handle portion  708 . 
         [0030]    Referring to  FIG. 8 , a cannulated bone screw  800  and a washer  802  are illustrated according to an exemplary embodiment of the present invention. The cannulated bone screw  100  includes a threaded end portion  804 , a non-threaded portion  806 , and a radial interlocking convex toothed surface  808  disposed near a screw head  810 . The screw head  810  includes keyed head flanges  812  for engaging a screw holder, drill, or the like. The threaded end portion  804  is operable to screw into a bone, such as a facet joint or the like. The cannulated bone screw  800  can be utilized to stabilize facet joints through an angular insertion of the cannulated bone screw  800  into a first facet and screwing the cannulated bone screw  800  into a second facet, the associated pedicle, or any other bony structure. Once fully engaged between the facets, pedicle, or other bony structure, the threaded portion  804  is embedded in the second facet, the associated pedicle, or any other bony structure, and the non-threaded portion  806  is in the first facet. Additionally, the washer  802  is operable to engage the screw head  108  and an outer surface of the first facet through a plurality of spikes  820  located on a bottom side of the washer  802 . An interior of the washer  802  includes an interlocking radial toothed pattern  830  on a superior concave surface. The washer  802  further includes an opening  832  dimensioned to receive the cannulated bone screw  800 . The interlocking radial toothed pattern  830  is operable to engage the radial interlocking convex toothed surface  808  to prevent rotational loosening of the cannulated bone screw  800 . 
         [0031]    Referring to  FIG. 9 , the cannulated bone screw  800  is illustrated engaged with the washer  802  according to an exemplary embodiment of the present invention. The opening  832  of the washer  800  is slid over the threaded portion  804  to the non-threaded portion  806 . As the threaded portion  804  is screwed into a bone, the spikes  820  on the washer  802  engage the bone, and the washer  802  engages the radial interlocking convex toothed surface  808  on the cannulated bone screw  800 . In the locked position, the interlocking concave/convex surfaces on the toothed surface  808  and the washer  802  prevent the screw from backing out while allowing the cannulated bone screw  800  to conform/pivot in order to accommodate different bone morphologies. 
         [0032]    Referring to  FIG. 10 , a drill guide and washer holder  1000  is illustrated according to an exemplary embodiment of the present invention. The drill guide and washer holder  1000  is operable to place the washer  802  on a surface, i.e. bone, and to guide a drill with the cannulated bone screw  800  through the washer  802  and the bone. The drill guide and washer holder  1000  includes a handle portion  1002 , a cylinder member  1004  disposed to the handle portion  1002 , and an end clasping mechanism  1006  disposed to an end of the cylinder member  1004 . The end clasping mechanism  1006  is configured to grasp and place the washer  802 . For example, the end clasping mechanism  1006  can include an inserter tube that contains the washer  802 . The handle portion  1002  includes a drill opening  1010  operable to receive a drill. The opening  1010  extends through the handle portion  1002 , the cylinder member  1004 , and the end clasping mechanism  1006  to enable the drill to engage the washer  802  and extend out of the end clasping mechanism  1006  to a bony structure or the like. 
         [0033]    Referring to  FIG. 11 , different views are illustrated of a cannulated drill  1100  according to an exemplary embodiment of the present invention. The cannulated drill  1100  can be utilized with the drill guide and washer holder  1000  to drill a pilot hole in a bone to receive the cannulated bone screw  800 . The cannulated drill  1100  includes a drill bit  1102  which in an exemplary embodiment may be 4 mm. The drill bit  1102  can be removable from the cannulated drill  1100  through a coupling mechanism  1104  disposed to an end of the cannulated drill  1100 . The coupling mechanism  1104  is disposed to a cylinder member  1106  which extends to a drill connection point  1108 . The drill connection point  1108  includes a connector  1110  for interfacing to a drill element. The connector  1110  translates a rotational force from the drill element through the cylinder member  1106  to enable the drill bit  1102  to rotate for drilling the pilot hole in a bone. For example, the cannulated drill  1100  can be utilized in the drill opening  1010  of the drill guide and washer holder  1000 . 
         [0034]    Referring to  FIG. 12 , different views are illustrated of a screw holder assembly  1200  and a screw holder  1202  for the cannulated bone screw  800  according to an exemplary embodiment of the present invention. The screw holder  1202  is operable to engage the screw head  810  through the keyed head flanges  812  on the cannulated bone screw  800 . For example, the screw holder  1202  can utilize similar mechanisms as described herein in  FIG. 5 . The screw holder  1202  is configured to snap over the keyed head flanges  812  in the screw head  810 . The screw holder  1202  includes a first arc member  1204  and a second arc member  1206 , each configured to engage one of the keyed head flanges  812  in the screw head  810 . The arc members  1204 ,  1206  each include a notch (not shown) which snaps on the keyed head flanges  812 , and a top of the arc members  1204 ,  1206  substantially mates with a top side of the toothed surface  808 . The screw holder  1202  further includes a first arc portion  1208  and a second arc portion  1210  offset from the arc members  1204 ,  1206 . The arc portions  1208 ,  1210  are operable to engage a top  1212  of the screw head  810  when the arc members  1204 ,  1206  are engaged to the keyed head flanges  812 . Collectively, the arc members  1204 ,  1206  and the arc portions  1208 ,  1210  define notches which are operable to engage the keyed head flanges  812 . In the engaged position, the screw holder  1202  is operable to translate a rotational force to the cannulated bone screw  800  to enable engagement of the washer  802  and a bone, such as through a pilot hole. The screw holder  1202  also further includes a first support member  1220  and a second support member  1222 . Each of the support members  1220 ,  1222  are disposed to the arc members  1204 ,  1206 , and the arc portions  1208 ,  1210  extend from the support members  1220 ,  1222 . The support members  1220 ,  1222  are disposed to a cylinder member  1230 . 
         [0035]    The screw holder assembly  1200  is operable to engage the screw holder  1202  through a coupling mechanism  1240 . The coupling mechanism  1240  can be disposed to the screw holder  1202 , to a cylinder member  1242 , or to neither. The cylinder member  1242  extends to a handle  1244 . A surgeon can utilize the handle  1244  while griping onto the cylinder member  1242  to maneuver the screw holder assembly  1200  to engage the cannulated bone screw  800 , to position the cannulated bone screw  800  into a washer  802  and pilot hole, and to screw the cannulated bone screw  800  into the bone. 
         [0036]    Referring to  FIG. 13 , a screw driver assembly  1300  is illustrated with a hexalobular design  1304  for a screw holder  1302  according to an exemplary embodiment of the present invention. The screw holder  1302  is operable to engage the screw head  810  through the keyed head flanges  812  and through a hexalobular design  1304  on the cannulated bone screw  800 . The screw driver assembly  1300  is similar to the screw holder assembly  1200  with the addition of the hexalobular design  1304 . The screw driver assembly  1300  includes a cylinder member  1310  and a handle  1312 . The cylinder member  1310  includes the screw holder  1302  at one end and the handle  1312  at the other end. 
         [0037]    Referring to  FIG. 14 , a rescue screw system  1400  is illustrated according to an exemplary embodiment of the present invention. The rescue screw system  1400  is operable to remove an inserted cannulated bone screw  800 . The rescue screw system  1400  includes one of the screw holders  1202 ,  1302 , a cylinder member  1402  disposed to the screw holder  1202 ,  1302  at one end and to a grip portion  1404  at another end, and a handle portion  1406  disposed to the grip portion  1404 . A surgeon can utilize the rescue screw system  1400  to engage the cannulated bone screw  800  and remove the cannulated bone screw  800  through rotational force applied through the grip portion  1404  and the handle portion  1406 . 
         [0038]    Referring to  FIG. 15 , different views are illustrated of the rescue screw system  1400  of  FIG. 14  according to an exemplary embodiment of the present invention. FIG.  15  illustrates a close-up view of the handle portion  1406  and the grip portion  1404 , and a close-up view of the cannulated bone screw  80  engaged to the screw holder  1202 ,  1302 . 
         [0039]    Although the present invention has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present invention, are contemplated thereby, and are intended to be covered by the following claims.