Abstract:
The present invention relates to stable fixation of spine segments, allowing for fusion in, e.g., skeletally mature patients. More particularly, the invention relates to a bone fixation device that can be affixed to vertebrae of a spine to provide reduction (or enlargement) capabilities and allow for fixation in the treatment of various conditions, including, e.g., spondyloslisthesis, degenerative disc disease, fracture, dislocation, spinal tumor, failed previous fusion, and the like, in the spine. The invention also relates to a method for delivering and implanting the bone fixation device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation application of U.S. Ser. No. 13/657,310, filed Oct. 22, 2012, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to stable fixation of spine segments, allowing for fusion in, e.g., skeletally mature patients. More particularly, the invention relates to a bone fixation device that can be affixed to vertebrae of a spine to provide reduction (or enlargement) capabilities and allow for fixation in the treatment of various conditions, including, e.g., spondyloslisthesis, degenerative disc disease, fracture, dislocation, spinal tumor, failed previous fusion, and the like, in the spine. The invention also relates to a method for delivering and implanting the bone fixation plating device. 
       BACKGROUND OF THE INVENTION 
       [0003]    Bones and bony structures are susceptible to a variety of weaknesses that can affect their ability to provide support and structure. Weaknesses in bony structures can have many causes, including degenerative diseases (e.g., degenerative disc diseases), tumors, fractures, dislocations and failed previous fusions. Some of these weaknesses can cause further conditions such as spondyloslisthesis wherein bony structures slip out of their proper position. 
         [0004]    In some cases of spinal surgery, it is known to use bone fixation plating devices (e.g., bone plate systems and rod and screw systems) to improve the mechanical stability of the spinal column and to promote the proper healing of injured, damaged or diseased spinal structures. Typically, corrective surgery can entail the removal of damaged or diseased tissue, a decompression of one or more neural elements, followed by the insertion of an interbody implant or bone graft for the purposes of a fusion or disc arthroplasty. In cases where spinal fusion is the desired surgical outcome, the surgery can often include implanting a bone plate or rod and screw system in order to immobilize adjacent vertebral bones to expedite osteogenesis across the vertebral segments. Accordingly, there is a need to improve on bone fixation plating devices. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention includes a bone fixation plating device and a method for delivering and implanting the bone fixation plating device in a patient. The bone fixation plating device can be affixed to vertebrae of a spine of the patient to facilitate bony fusion and stabilization of the spine. The method includes delivering the bony fixation device to a treatment area of the spine, and affixing the device to vertebrae of the spine to, e.g., facilitate bony fusion and stabilization of the spine. 
         [0006]    In some embodiments, a bone fixation plating device is provided for therapeutic treatment of a patient, the device comprising: a plate having a locking device receiving hole and a carriage receiving slot, wherein the locking device receiving hole and the carriage receiving slot are adjacent to one another and the locking device receiving hole is configured to receive and pass there-through a portion of a first screw; and a carriage comprising an intermediate portion that is configured to fit in the carriage receiving slot, the carriage comprising a hole to receive and pass there-through a portion of a second screw. 
         [0007]    In some embodiments, the carriage can comprise an upper flange and a lower flange. The carriage can comprise a two piece assembly that includes an upper carriage portion and a lower carriage portion. In some embodiments, the carriage can be a single piece structure. One of the upper flange and the lower flange can comprise an indentation that is configured to engage a guide in the carriage receiving slot. One of the upper flange and the lower flange can comprise a reverse bevel. 
         [0008]    The device can further comprise a further carriage that is configured to fit in the carriage receiving slot together with said carriage, said further carriage comprising a hole to receive and pass there-through a portion of a screw, wherein said carriage and said further carriage are movable in the carriage receiving slot along a longitudinal axis of the plate. 
         [0009]    The device can further comprise a screw having a post. The screw can comprise a first thread and a second thread, wherein one of the first and second threads comprises a fine thread. The other of the first and second threads can comprise a coarse thread. A proximal end of the screw can comprise an open-ended guide wire capture slot. The threaded shaft of each of the two bone screws can be tapered at the distal end. 
         [0010]    The device can further comprise a locking device. The locking device can comprise a cutout. The locking device receiving hole of the plate can comprise a rib that is configured to lockably engage the locking device. The locking device can comprises a ball shape or a tulip shape. 
         [0011]    According to a further aspect of the invention, a bone fixation plating device is provided for therapeutic treatment of a patient, the device comprising: a plate having a locking device receiving hole and a carriage receiving slot, wherein the locking device receiving hole and the carriage receiving slot are adjacent to one another and the locking device receiving hole is configured to receive and pass there-through a portion of a first screw; a carriage comprising an intermediate portion that is configured to fit in the carriage receiving slot, the carriage comprising a hole to receive and pass there-through a portion of a second screw; and a locking device that is configured to fasten to one of said first and second screws and secure the plate to the first and second screws. The carriage can comprise a two piece assembly that includes an upper carriage portion and a lower carriage portion, or a single piece structure, wherein the carriage is movable in the carriage receiving slot along a longitudinal axis of the plate. One of the upper flange and the lower flange can comprise an indentation that is configured to engage a guide in the carriage receiving slot. 
         [0012]    According to a further aspect of the invention, a method is provided for implanting a bone fixation plating device, the method comprising: positioning a plate having a locking device receiving hole and a carriage receiving slot that includes a carriage proximate to a plurality of screws that have been implanted in bony structures; mounting the plate and carriage on to respective portions of the plurality of screws; securing the plate and carriage to the plurality of screws with an equal number of locking devices. The method can further comprise adjusting the location of the carriage with respect to the locking device receiving hole based on the spacing between the plurality of screws. The method can further comprise selecting a plate length and curvature based on the spacing of the screws and the anatomical needs of the patient. The method can further comprise contouring, twisting, and/or bending the plate based on the anatomical needs of the patient. 
         [0013]    Additional features, advantages, and embodiments of the invention can be set forth or apparent from consideration of the following attached detailed description and drawings. Moreover, it is to be understood that both the foregoing summary of the invention and the following attached detailed description are exemplary and intended to provide further explanation without limiting the scope of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which: 
           [0015]      FIGS. 1A and 1B  show different views of a bone fixation plating device that is constructed according to an embodiment of the invention; 
           [0016]      FIGS. 2A and 2B  show different partially exploded views of the bone fixation plating device of  FIGS. 1A and 1B ; 
           [0017]      FIG. 3  shows a side cut view of the bone fixation plating device of  FIG. 2A ; 
           [0018]      FIG. 4  shows a side cut view of a portion of the bone fixation plating device of  FIG. 2A ; 
           [0019]      FIG. 5  shows an example of a single-level bone fixation plate that can be include in the bone fixation plating device of  FIGS. 1A and 1B ; 
           [0020]      FIG. 6  shows an example of a multi-level bone fixation plate that can be included in the bone fixation plating device of  FIGS. 1A and 1B ; 
           [0021]      FIGS. 7A and 7B  depict examples of the bone screw that can be used in a bone fixation plating device; 
           [0022]      FIGS. 8A and 8B  depict examples of a carriage that can be included in the bone fixation plating device of  FIG. 1A ; and 
           [0023]      FIG. 9  shows another embodiment of a bone fixation plating device according to some embodiments. 
           [0024]      FIG. 10  shows another embodiment of a bone fixation plating device according to some embodiments. 
       
    
    
       [0025]    The present invention is further described in the detailed description that follows. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    The aspects of the present invention and the various features and advantageous details thereof are explained more fully with reference to the non-limiting aspects and examples that are described and/or illustrated in the accompanying drawings and detailed in the following description. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale, and features of one aspect can be employed with other aspects as the skilled artisan would recognize, even if not explicitly stated herein. Descriptions of well-known components and processing techniques can be omitted so as to not unnecessarily obscure the aspects of the present invention. The examples used herein are intended merely to facilitate an understanding of ways in which the present invention can be practiced and to further enable those of skill in the art to practice the aspects of the present invention. Accordingly, the examples and aspects herein should not be construed as limiting the scope of the present invention, which is defined solely by the appended claims and applicable law. Moreover, it is noted that like reference numerals represent similar parts throughout the several views of the drawings. 
         [0027]    The terms “a,” “an,” and “the,” as used herein, are defined to mean “one or more,” unless expressly specified otherwise. The terms “including,” “having,” “comprising,” and variations thereof, as used herein, are defined to mean “including, but not limited to,” unless expressly specified otherwise. 
         [0028]      FIGS. 1A and 1B  show different views of a bone fixation plating (or posterior lumbar implant) device  100  that is constructed according to an embodiment of the invention. The bone fixation plating device  100  comprises a bone fixation plate  10 , a pair of posted bone screws  20  (identified individually as  20   a  and  20   b ), and a pair of locking balls  30  (identified individually as  30   a  and  30   b ). In some embodiments, bone screw  20   b  can be received in a carriage  40  that can slide along a length of the device  100  until a desired distance of separation between the posted screws  20   a  and  20   b  is achieved. Once a desired distance of separation has been achieved, the carriage  40  can be compressed and locked in place along the length of the plate  10 . In addition, in some embodiments, the bone fixation plating device  100  is configured to allow the posted bone screws  20   a  and  20   b  to rotate and/or pivot polyaxially with regard to the bone fixation plate  10 . Accordingly, the device  100  not only accommodates selective positioning of the screws  20   a  and  20   b  relative to one another, but also desirable polyaxial adjustment. 
         [0029]    In  FIG. 1A , the bone fixation plating device  100  is shown in an assembled (or substantially assembled) configuration, wherein the longitudinal axes C-C of the pair of posted bone screws  20   a  and  20   b  are aligned substantially parallel to each other and substantially perpendicular to a plane of the bone fixation plate  10 . 
         [0030]    In  FIG. 1B , the bone fixation plating device  100  is shown in an assembled (or substantially assembled) configuration, wherein the longitudinal axes C-C of the pair of posted bone screws  20   a  and  20   b  are not parallel to each other, but instead, the longitudinal axis of one of the posted bone screws  20   b  is offset with respect to the longitudinal axis of the other posted bone screw  20   a . Further, the longitudinal axis of one of the posted bone screws  20   a  is positioned substantially perpendicular to the plane of the bone fixation plate  10 , and the longitudinal axis of the other posted bone screw  20   b  is positioned at an angle significantly less (or greater) than 90° (e.g., about 65°) with respect to the plane of the bone fixation plate  10 . As seen in  FIG. 1B , each of the posted bone screws  20  can advantageously be moved polyaxially in all directions at an angle of between, e.g., about 0° and about 80°, or between about 0° and about 25° with respect to an axis normal (or perpendicular) to the plane of the bone fixation plate  10 . In some embodiments, the range of movement can be greater or less than about 0° to about 25°. Positioning of the bone screw  20   a  or  20   b  at an angle relative to an axis normal (or perpendicular) to the plane of the bone fixation plate  10  allows the plate  10  to accommodate for movements in the vertebrae and/or for compression of the bone grafts that are placed between vertebrae. In addition, by providing the bone screws  20   a  and  20   b  with polyaxial adjustability, this advantageously allows the plate to cooperate with a variety of different anatomies. 
         [0031]    Further, as shown in  FIGS. 1A and 1B , the device  100  allows for the relative positioning of the posted bone screws  20   a  and  20   b  to be modified. The device  100  provides a carriage  40  for at least one of the bone screws  20   b , which allows the screw  20   b  to be adjusted along a length of the plate  10 . In some embodiments, the other screw  20   a , can be in a relatively fixed position along a length of the plate  10 . As shown in  FIG. 1B , the carriage  40  can include an upper flange  42  and a lower flange  46  that can ride along a length of the plate  10 , such that the plate  10  serves as a track for the carriage  40 . In some embodiments, as shown in  FIG. 1B , the flanges  42  and  46  of the carriage  40  can extend along top and bottom surfaces of the plate  10 . In alternative embodiments, the flanges  42  and  46  of the carriage  40  can extend within a recess formed in sidewalls of the plate  10 . Once the bone screw  20   b  is placed in a desired position relative to the bone screw  20   a , the carriage  40  can be compressed and secured onto the plate  10  (e.g., via downward application of the compression ball  30   b  along the top threads of the bone screw  20   b , as discussed in more detail below), thereby preventing or restricting movement of the carriage  40  along the plate  10 . 
         [0032]      FIGS. 2A and 2B  show different partially exploded views of the bone fixation plating device  100 . In these views, the compression balls  30   a  and  30   b  have not yet been secured to the bone screws  20   a  and  20   b . As shown in the figures, each of the bone screws  20   a  and  20   b  includes a top threaded section ( 251   a ,  251   b ) and a bottom threaded section ( 252   a ,  252   b ), The top threaded sections  251   a ,  251   b  of the screws pass through the plate  10  and accommodate the compression balls  30   a ,  30   b , which are internally threaded, while the bottom threaded sections  252   a ,  252   b  are insertable into a vertebral body, such as the pedicle. 
         [0033]    With respect to the first bone screw  20   a , which is in a relatively fixed position along the length of the plate  10 , the bone screw  20   a  can be polyaxially adjustable relative to the plate  10  prior to downwardly securing the compression ball  30   a  thereon. In operation, as the compression ball  30   a  travels down the top threaded section  251   a  of the bone screw  20   a , this pulls the bone screw  20   a  upwards, such that a top of a post section  27   a  contacts an underside of the plate  10 . As shown in  FIG. 2A , the post  27   a  of the screw  20   a  comprises a widest section of the screw, and is configured to abut against an extension portion  12  formed on the plate  10 . As the compression ball  30   a  is downwardly threaded on the screw  20   a , the bottom of the compression ball  30   a  compresses inwardly (e.g., via one or more cut-outs  37 ) into a compression fit with the plate  10 , thereby locking the polyaxial motion of the screw  20   a  relative to the plate  10 . 
         [0034]    With respect to the second bone screw  20   b , which is in a variable position along the length of the plate  10 , the bone screw  20   b  can be polyaxially adjustable relative to plate  10  prior to downwardly securing the compression ball  30   a  thereon. In addition, the position of the bone screw  20   b  relative to bone screw  20   a  can be modified, as the carriage  40  is moved along the length of the track. In operation, as the compression ball  30   b  travels down the top threaded section  251   b  of the bone screw  20   b , this pulls the bone screw  20   b  upwards, such that a top of a post section  27   b  contacts an underside of the plate  10 . As shown in  FIG. 2A , the post  27   b  of the screw  20   b  comprises a widest section of the screw, and is configured to abut against the bottom of the carriage  40 . As the compression ball  30   b  is downwardly threaded on the screw  20   b , the bottom of the compression ball  30   b  compresses inwardly (e.g., via one or more cut-outs  37 ) into a compression fit with the carriage  40  and plate  10 . As the compression ball  30   b  is downwardly threaded, the post  27   b  of the screw is pulled upwards to abut and push against the bottom flange  46  of the carriage  40 , while the top of the compression ball  30   b  pulls down on the top flange  42  of the carriage  40 , thereby compressing the carriage  40  against the plate  10 . Thus, the downward threading of the compression ball  30   b  on the screw  20   b  advantageously locks the polyaxial motion of the screw  20   b  relative to the plate  10 , and compresses the carriage  40  to secure the relative position of the screw  20   b  relative to screw  20   a.    
         [0035]      FIGS. 3 and 4  show side cut views of the bone fixation plating device  100 . In particular,  FIG. 3  shows a side cut view of the bone fixation plating device  100  cut along the longitudinal axis of the bone fixation plate  10  and along an axis perpendicular to the longitudinal axes of the posted bone screws  20 ; and,  FIG. 4  shows a side cut view of the bone fixation plate  10  and a locking ball  30  cut along the longitudinal axis of the bone fixation plate  10 . As seen in  FIG. 4 , the locking ball  30 , which is an example of a locking device that can be used in the bone fixation plating device  100 , comprises an aperture (or opening)  33  and an internal threading  35  that is constructed to receive a portion of the screw  20  and mate with and securely fasten to a corresponding top threaded section  251  (shown in  FIG. 7A ) of the screw  20 . The locking ball  30  can include one or more cut-outs  37  (e.g., shown in  FIG. 2A ) that are configured to allow a portion of the body of the locking ball  30  to be compressed inward (e.g., in the direction of the aperture  33 ), so as to firmly secure and lock the locking ball  30  to a portion of screw  20 . The locking ball  30  can further include a ratcheting recess  38 , which can be configured to receive, e.g., a hexagonal tool such as a hex drive, wrench, or other known tool to rotate the locking ball  30 , securing it to the screw  20 . The locking ball  30  can include, e.g., a pear-shape, a spherical shape, or any other shape that allows the locking ball  30  and screw  20  to pivot and/or rotate with respect to the bone fixation plate  10 . 
         [0036]      FIG. 5  shows an example of the bone fixation plate  10  and the carriage  40  that can be included in the bone fixation plating device  100 . As shown from this view, the carriage  40  comprises a monolithic member assembled to the plate  10 . In other embodiments, the carriage  40  can be formed of two or more members that are rotatably coupled, press-fitted or otherwise secured to one another along the plate  10 . As shown in  FIG. 5 , the carriage  40  occupies only a certain amount of space within the plate  10 . Areas adjacent to the carriage  40  can be used to insert other devices, such as spacers, through the plate  10  and into a desired anatomical location. Accordingly, in some embodiments, the fixation plating device  100  can be used with other devices (e.g., spacers) as part of a broader surgical system (e.g., for fusion). 
         [0037]      FIG. 6  shows an example of a bone fixation plate  101  and a plurality (e.g., two) carriages  40  that can be included in the bone fixation plating device  100 . In this embodiment, three screws—one in a relatively fixed position, and two in variable positions along the length of the plate—can be accommodated. The bone fixation plate  101  can be substantially the same as, or similar to the bone fixation plate  10 , except that the slot  14  can be lengthened in a longitudinal axis A-A direction of the bone fixation plate to accommodate a plurality of carriages  40 . 
         [0038]    Referring to  FIG. 5 , the bone fixation plate  10  can include, e.g., a single-level pre-lordosed plate that can be provided with an integrated carriage  40 . The bone fixation plate  10  can include a locking device receiving hole  12  and a carriage receiving slot  14 , in which a portion of a screw  20  (e.g., shown in  FIG. 1A ) can pass through and be used to fasten the bone fixation plate  10  to, e.g., the vertebrae of a spine. The carriage receiving slot  14  can include an inner perimeter that forms a pair of carriage guides  141 ,  142 , and a carriage stop  143 . The pair of carriage guides  141 ,  142  can be substantially parallel to each other along the longitudinal axis A-A. The carriage guides  141 ,  142  serve to guide and support the carriage(s)  40 , allowing the carriage  40  to be moved along the longitudinal axis A-A of the bone fixation plate  10 . The carriage stop  143  can function to prevent the carriage  40  from, e.g., falling from the bone fixation plate  10 . The bone fixation plate  10  can be secured to, e.g., two vertebrae in order to maintain the vertebrae integrally with respect to one another in a desired orientation and at a desired spacing from one another. The locking device receiving hole  12  and the carriage receiving slot  14  are adjacent to one another along the longitudinal axis A-A of the bone fixation plate  10 . The bone fixation plate  10  can be planar and can have length and width dimensions that significantly exceed its thickness dimensions. The bone fixation plate  10 , however, can have shapes other than planar, without departing from the scope or spirit of the invention. 
         [0039]    The bone fixation plate  10  has an anterior surface  16  and a posterior surface  18 . The length of the bone fixation plate  10  along the longitudinal axis A-A is generally greater than its width along its transverse axis B-B. Furthermore, the bone fixation plate  10  can be curved in a longitudinal plane that is parallel to the anterior surface  16  and that includes the longitudinal axis A-A. The bone fixation plate  10  can be curved in a transverse plane that is perpendicular to the anterior surface  16  and that includes the transverse axis B-B. The bone fixation plate  10  can be pre-lordosed or can be curved during surgical implantation. 
         [0040]    The direction of the curvature in both the longitudinal and transverse planes can be substantially the same (or different), such that the posterior surface  18  of the bone fixation plate  10  can be concave and the anterior surface  16  can be convex. The radius of the curvature in the longitudinal plane A-A can be selected to match the desired lordosis of the section of the vertebral column to which the bone fixation plate  10  can be affixed. In addition, the radius of curvature in the transverse plane can be selected to conform to the transverse curvature of the anterior surfaces of the vertebrae. The radius of the curvature in the longitudinal plane A-A can, therefore, be different from the radius of curvature in the transverse plane and the curvatures do not necessarily form simple arc shapes. 
         [0041]    While the bone fixation plate  10  can have a generally rectangular shape with rounded corners and edges, other shapes can be utilized. The bone fixation plate  10  can be made of, or include any material, such as, e.g., a metal, an alloy, a synthetic material (e.g., carbon fiber), or any combination thereof, that would allow the plate  10  to maintain its structural integrity while allowing for a desired amount of resiliency. The material used can be, or can include a bio-compatible material. The material is capable of withstanding the conditions of a body over a desired period of time. The bone fixation plate  10  can be formed from a material that minimizes interference with magnetic resonance imaging techniques for post-operative evaluations. The bone fixation plate  10  can be made from, e.g., titanium, cobalt chrome, stainless steel or other alloys or materials that are suitable for surgical implantation. 
         [0042]    The locking device receiving hole  12  extends through the entire thickness of plate  10  and is sized to receive a locking device (e.g., the locking ball  30  shown in  FIG. 4 , or the locking device shown in  FIG. 9 ) that is capable of retaining the bone screw (e.g., shown in  FIGS. 7A-7B ) in the bony structure (e.g., vertebrae) (not shown) in which it is inserted and prevent the screw from backing out of bone fixation plate  10  after the bone fixation plating device  100  is implanted in a patient. In some embodiments, the portion of plate  10  that defines the locking device receiving hole  12  can comprise ribbing configured to mate with, e.g., cutouts provided in the locking device (shown in  FIG. 8C ). 
         [0043]    The bone fixation plate  10  includes the carriage receiving slot  14  which accommodates a carriage  40  (e.g., shown in  FIG. 5  or  FIGS. 8A-8C ). The carriage receiving slot  14  includes the carriage guides  141 ,  142 , and carriage stop  143 , and extends through the entire thickness of plate  10  and has a length (along the longitudinal axis A-A) that is sized to be larger than a carriage  40 . Typically, the length of the carriage receiving slot  14  is large enough to integrate at least one carriage  40  with space remaining on one or both sides of the carriage  40 . The space remaining on either or both sides of the carriage  40  can advantageously provide one or more windows in the plate  10  through which a surgeon can access the bony anatomy beneath the posterior lumbar implant device  100 . In some embodiments, additional devices, such as spacers, can be inserted through these windows, such that the plate device  10  and spacers can be part of a broader fusion system. The width of the carriage receiving slot  14  (i.e., the distance between the guides  141 ,  142 , along the transverse axis B-B) is sized to engage an outside surface of an intermediate portion of a carriage so that the carriage  40  is securely retained in the carriage receiving slot  14 . 
         [0044]      FIG. 6  shows another example of a bone fixation plate  101  that can be included in the bone fixation plating device  100  (e.g., shown in  FIG. 1A ). The bone fixation plate  101  includes a multi-level plate. In the bone fixation plate  101 , the length of a carriage receiving slot  140  (along the longitudinal axis A-A) is sized to be larger than two or more carriages  40  such that two or more carriages can be integrated into plate  10 . The length of the carriage receiving slot  140  is large enough to integrate at least two carriages  40  with space remaining between each of the two carriage assemblies and/or space remaining on one side of at least one of the two carriages. The space remaining between each of the two carriages and/or space remaining on one side of at least one of the two carriages provides one or more windows in the plate  101  through which a surgeon can access the bony anatomy beneath the posterior lumbar implant. 
         [0045]      FIG. 7A  shows an enlarged view of the bone screw  20 , which can be included in the bone fixation plating device  100  (e.g., shown in  FIG. 1A ). The bone screw  20  comprises a proximal end  21 , a distal end  23  and a threaded shaft  25  extending distally from the proximal end  21  along a longitudinal axis C-C. The threaded shaft  25  can include two more different types of threading, including, first threading of a top threaded section  251  and a second threading of a bottom threaded section  252 . In some embodiments, the first threading of the top threaded section  251  can be a fine threading that is configured to engage and securely fasten to the screw  20  to a locking device (e.g., the locking ball  30  shown in  FIG. 1A ). The second threading of the bottom threaded section  252  can be a coarse threading that is configured to engage and securely fasten the screw  20  to, e.g., a bone. In some embodiments, the pitch of the threads of the top threaded section  251  differs from the pitch of the threads of the bottom threaded section  252 . The top threaded section  251  and bottom threaded section  251 ,  252  can have different or substantially the same diameters. The first and/or second threads of the different threaded sections  251 ,  252  can have varying diameters. 
         [0046]    In some embodiments, the proximal end  21  of the bone screw  20  can be shaped to mate with a tool adapted to rotate the screw  20  (e.g., to rotate the screw  20  in order to implant the screw into a bony structure). For instance, the proximal end  21  of the bone screw  20  can comprise a hexagonal recess that receives a hexagonal tool such as a hex drive, or a slot or cross that receives a screwdriver. The bone screw  20  can further comprise a post  27  that is positioned between the distal end  23  and the proximal end  21 . The post  27  extends away from the threaded shaft  25  in a plane that is substantially perpendicular to the longitudinal axis C-C. 
         [0047]    The bone screw  20  is comprised of, e.g., a metal, an alloy, a synthetic material, or any combination thereof. The bone screw  20  is typically made of a material that allows the screw to maintain its structural integrity while allowing for a desired amount of resiliency. The material used is usually bio-compatible and is capable of withstanding the conditions of a body over a desired period of time. 
         [0048]    As seen in  FIG. 7A , the threaded shaft  25  of the bone screw  20  can be tapered at the distal end  23  and an outer perimeter of the post  27  can comprise notches  253  that can be engaged by a tool (not shown) to rotate and drive the screw  20  into bony tissue (not shown). 
         [0049]      FIG. 7B  shows another example of a bone screw  200  that can be included in the bone fixation plating device. The proximal end  210  of the screw  200  can comprise an open-ended guide wire capture slot to accommodate a guide wire  29 . Utilization of a guide wire  29  in each of the bone screws  200  can enable a surgeon to position the locking device receiving hole  12  and carriage  40  of a plate  10  over the bone screws  200  more easily than in cases where the guide wire  29  is not employed. 
         [0050]      FIG. 8A  shows an example of the carriage  40  that can be included in the bone fixation plating device. In some embodiments, the carriage  40  can be monolithic. In other embodiments, the carriage  40  can be formed of multiple pieces (e.g., rotatably coupled together). The carriage  40  comprises an upper flange  42  and a lower flange  46  connected by (or integrally formed with) an intermediate portion (guide)  44  along an axis D-D. The intermediate portion  44  comprises an outside surface  44   a  and an inside surface  44   b . The inside surface  44   b  defines a locking device receiving hole and the outside surface  44   a  is configured to mate with the carriage guides  141 ,  142  in the plate  10  (e.g., shown in  FIG. 5 ). In some embodiments, the inside surface  44   b  can comprise ribbing configured to engage with the outside surface of the intermediate portion of the locking device (e.g., locking ball  30  shown in  FIG. 1A ) to securely hold the locking device in the locking device receiving hole once the locking device is inserted therein. The inside surface  44   b  can include, e.g., a flared surface portion that is constructed to allow the locking device to pivot and/or rotate about the axis D-D. Advantageously, the carriage  40  is provided with a series of surface cuts  49 , which increase the compressibility of the carriage  40 . 
         [0051]    The carriage  40  can be made of the same material as (or a different material from) the plate  10 . The carriage  40  can be made of a material that comprises, e.g., a metal, an alloy, a synthetic material, or any combination thereof. The material can be bio-compatible and capable of withstanding the conditions of a body over a desired period of time. Carriage  40  can be formed from a material that minimizes interference with magnetic resonance imaging techniques for post-operative evaluations. The carriage  40  can be made of a material that comprises, e.g., titanium, cobalt chrome, stainless steel or other alloys or materials that are suitable for surgical implantation. 
         [0052]      FIG. 8B  shows the undersides of the upper flange  42  and lower flange  46  of the carriage  40  of  FIG. 8A  in further detail. In particular, the underside of the upper flange  42  can comprise an indentation  42   a  along one (or two) of the edges of the flange  42  that reduces the thickness of the upper flange  42  so that it can contact and engage the anterior surface  16  of the plate  10  (e.g., the guide  141 ,  142  shown in  FIG. 5 ). More specifically, the indentation  42   a  allows the upper flange  42  to engage and overlap with the anterior surface  16  of the portion of the plate  10  that defines the guides  141 ,  142  of the carriage receiving slot  14 , thereby preventing the upper flange  42  from twisting or turning while securely, with the assistance of the lower flange  46 , holding the carriage  40  in the plate  10 . The lower flange  46  can also include a similar indentation (not shown) to the indentation  42   a.    
         [0053]    Also seen in  FIG. 8B  is the underside of the lower flange  46  of the carriage assembly  40  shown in  FIG. 8A . As seen in  FIG. 8B , the underside of the lower flange  46  of the carriage  40  can comprise a reverse bevel  46   a . When the proximal end  21  of the bone screw  20  is inserted into and through the locking device receiving hole of the carriage  40  (or plate  10 ), and then into the aperture  33  (e.g., shown in  FIG. 4 ) in the locking device, the locking device can be turned to mate the locking device  30  to the screw  20  and pivotally fasten the locking device and screw  20  to the carriage  40  (or plate  10 ). The reverse bevel  46   a  can engages with the post  27  in the bone screw  20  to provide a pivot stop for the screw  20  and locking device  30 , thereby preventing the screw  20  from pivoting beyond a predetermined threshold (e.g., about 25°) with respect to the normal to the plane of the plate  10 . 
         [0054]    The locking device receiving hole  12  of plate  10  and the locking device receiving hole of the carriage  40  (e.g., shown in  FIG. 4 ) allow the bone screw  20  to be inserted in through and locked at an angle of (in some embodiments), e.g., between about 0° and 25° away from normal axis to the plane of plate  10  and of the carriage  40  (e.g., at an angle of about 0° and 25° away from an axis that is perpendicular to the plane of plate  10  and at an angle of, e.g., about 0° and 25° away from the axis D-D of the carriage  40 , respectively). 
         [0055]      FIG. 8B  illustrates further details of the outside surface  44   a  of the intermediate portion  44  of the carriage  40 . As seen, the outside surface  44   a  of the intermediate portion  44  can comprise a helical groove  48  that aids the carriage  40  in translating along the longitudinal axis A-A of the carriage receiving slot  14 . The helical groove  48  can enable the carriage  40  to lock into a particular position within the carriage receiving slot  14 . 
         [0056]      FIG. 9  illustrates another example of a bone fixation plate  1000 , a carriage  400 , and a plurality of locking devices  300 . In some embodiments, the locking devices  300  are of similar construction to the compression balls described above. 
         [0057]    The bone fixation plate  1000  includes a carriage receiving slot  1400 , which comprises a pair of substantially parallel guides  1410 ,  1420 . The carriage receiving slot  1400  can further include a carriage stop  1430 . The walls of the guides  1410 ,  1420  and the carriage stop  1430  can be, e.g., annular, substantially flat, or have any other surface shape that can engage and secure the carriage  400  to the bone fixation plate  1000 . 
         [0058]    The carriage  400  comprises an upper carriage portion  410  and a lower carriage portion  420 . The upper carriage  410  can include a plurality of cutouts  1412 . The bottom carriage  420  can be configured such that it securely mates with the upper carriage  410  via a rotational fit, a press fit, a compression fit or other type of fit. In some embodiments, the cutouts  1412  of the upper carriage portion  410  can allow the lower edge of the upper carriage portion  410  to expand and securely engage the lower carriage portion  420 , thereby forming a single-piece carriage that can ride along the rails of the plate  1000 . 
         [0059]    The carriage  400  can be moved along the longitudinal axis A-A of the carriage receiving slot  1400  of the plate  1000 . When the carriage  400  translates along the longitudinal axis A-A of the carriage receiving slot  1400 , the relative position of the bone screws  20   a  and  20   b  associated with the plate  1000  is changed and dynamic compression (or expansion) is provided between multiple bony structures secured to the plate  1000 . The carriage  400  can be configured to allow for polyaxial pivoting and/or rotation of a screw received within the carriage until a locking device  300  is inserted therein and fastened to the carriage  400 , As described above, a screw  20   b  (e.g., a pedicle screw) can extend through the carriage  400  and the plate  1400 . The locking device  300  can be downwardly threaded onto the screw  20   b , thereby compressing the upper carriage  410  and lower carriage  420  in a like manner as discussed above. Once the locking device  300  is downwardly threaded, this helps lock the polyaxial angle of the screw  20   b  relative to the plate  10 , as well as the relative distance between the screw  20   b  and another screw  20   a  received within the plate. 
         [0060]    The locking device  300  comprises a main body  310  having an upper portion  310   a , a lower portion  310   b , a top  310   c  and a bottom  310   d . The top  310   c  of the locking device  300  can be shaped to mate with a tool adapted to rotate the locking device  300  (e.g., to rotate the locking device  300  within the locking device receiving hole of the carriage  400 , or plate  1000 , such that the locking device  300  mates with the carriage  400  or plate  1000 ). For instance, the top  310   c  of the locking device  300  can comprise a hexagonal recess (as shown in  FIG. 8C ) that receives a hexagonal tool such as a hex drive, or a slot or cross that receives a screwdriver. Alternatively, the top  310   c  of the locking device  300  can be configured with a protruding engagement surface that can engage with a tool or device having a corresponding recess. The upper portion  310   a , together with the top  310   c , defines an aperture dimensioned to receive a bone screw  20  that transcends through the lower portion  310   b  of the locking device. 
         [0061]    The lower portion  310   b  of the locking device  300  comprises an outside surface  330  and an inside surface (not shown). The outside surface  330  is shaped and configured to mate with the locking device receiving hole of the carriage  400  and/or the plate  1000 . The lower portion  310   b  can comprise cutouts  335  that are capable of compression to enable lockable mating with ribbing in the locking device receiving hole of carriage assembly  400  and/or plate  1000 . The locking device  300  comprises an aperture (not shown) that is dimensioned to receive a bone screw  20 . The inside surface (not shown) of locking device  300  can comprise threading that is capable of mating with the threads of the threaded shaft  25  of a bone screw  20 . 
         [0062]    In some embodiments, the aperture (not shown) in the locking device  300  can be a keyhole-shaped passage (not shown) that includes a central cylindrical portion (not shown) that receives the proximal end  21  of a bone screw  20 . The cutouts  335  permit expansion and reduction in the size of the central cylindrical portion. When the size of the central cylindrical portion is reduced, the proximal end  21  of the bone screw  20  is secured within the locking device  300 . 
         [0063]    The outside surface of the upper portion  310   a  can have a shape of, e.g., a bowl, a cup, a cone, or the like, wherein a top part of the upper portion  310   a  can have a diameter that is the same or different from the diameter of the bottom part of the upper portion  310   a . The outside surface  330  of the lower portion  310   b  of the locking device  300  can have an inverted shape to that of the upper portion  310   a , such that the upper portion  310   a  and lower portion  310   b  can be mirror images of one another when viewed relative to a longitudinal axis E-E. Alternatively, the upper portion  310   a  and lower portion  310   b  can be shaped differently. 
         [0064]      FIG. 10  shows an example of a bone fixation plating device  1001  that comprises a locking device  50  including a tulip shaped attachment. Advantageously, the tulip shaped attachment can receive other implants (e.g., rods) to assist in future revisions to the system. In some embodiments, the tulip shaped attachment is detachable from the rest of the locking device. 
         [0065]    The locking device  50  comprises a main body  51  having an upper portion  51   a  and a lower portion  51   b . The upper portion  51   a  of the locking device  50  is defined by an outside wall  53  which has a proximal end  53   a  and a distal end  53   b . The outside wall  53  can comprise two open-ended slots  53   c  and  53   d  positioned opposite of one another relative to a longitudinal axis I-I. The two open-ended slots  53   c  and  53   d  can extend distally from the proximal end  53   a  to the distal end  53   b  of the outside wall  53  and can be sized to receive a rod. 
         [0066]    The distal end  53   b  of the outside wall  53  can comprise a screw-receiving aperture (not shown) that transcends the distal end  53   b  of the upper portion  51   a  to reach the lower portion  51   b . The screw-receiving aperture (not shown) can be large enough to receive the proximal end  21  of a bone screw  20  inserted through the lower portion  51   b  of the locking device  50 , or another fastening device to be used with a rod. 
         [0067]    The lower portion  51   b  can be shaped e.g., as an inverted bowl or cup, wherein the upper part of the lower portion  51   b  can have a diameter that is smaller than the diameter of the lower part of the lower portion. The lower portion  51   b  of the locking device comprises an outside surface  55  and an inside surface (not shown). The outside surface  55  can be shaped and configured to mate with the locking device receiving hole of the carriage  40  and/or of plate  10 . Typically, the outside surface  55  comprises threads that are capable of threadably mating with ribbing in the locking device receiving hole of a carriage  4000  and/or a plate  1010 . 
         [0068]    The inside surface (not shown) defines an aperture (not shown) that is dimensioned to receive a bone screw  20  according to the disclosure. The aperture (not shown) can be a keyhole-shaped passage (not shown) that includes a central cylindrical portion (not shown) that receives a bone screw  20  and one or more cutouts (not shown) which permit expansion and reduction in the size of the central cylindrical portion. When the size of the central cylindrical portion is reduced, the bone screw  20  is secured within the tulip-shaped locking device  50 . 
         [0069]    Referring to  FIG. 1A , the bone fixation plate device  100  can be delivered to, and implanted into a patient. A method of implanting the bone fixation plate device  100  can include drilling one or more holes into a location of one or more bony structures (e.g., vertebrae) in the patient. A first screw  20   a  and plate  10  having a carriage  40  attached thereon can be provided, wherein the first screw  20   a  is polyaxially adjustable relative to the plate  10 . The first screw  20   a  extends through a first slot in the plate  10  and can be inserted into the hole in the vertebrae. A compression ball  30   a  can be downwardly threaded onto the top of the first screw  20   a  to thereby secure the angle of the screw  20   a  relative to the plate  10 . A second screw  20   b  can also be provided and inserted into a hole formed in the vertebrae. The second screw  20   b  can extend through the carriage  40  of the plate  10 , which can slide along a length of the plate  10 . Like the first screw  20   a , the second screw  20   b  is polyaxially adjustable relative to the plate  10 . A compression ball  30   b  can be downwardly threaded on to the top of the second screw  20   b  to thereby secure the angle of the screw  20   b  relative to the plate  10 . The compression ball  30   b  also helps to compress the carriage  40 , thereby securing the relative position of the second screw  20   b  relative to the first screw  20   a.    
         [0070]    In other embodiments, both screws  20   a  and  20   b  are inserted into predetermined holes formed in the vertebrae. Once the screws  20  are properly secured and in position, a bone fixation plate  10  having an appropriate length and curvature can be selected. In some embodiments, the bone fixation plate  10  can be preselected based on the desired spacing between the screws  20 , so as to provide the proper spacing between the screw receiving opening  12  in the plate  10  and the screw receiving opening in the carriage  40 . The plate  10  can be pre-curved for both lordotic and extra-lordotic conditions. Additional contouring can be possible utilizing an instrument (not shown) to bend or twist the plate  10  based on anatomical needs of the particular patient. 
         [0071]    Once the plurality of bone screws  20  are securely and properly affixed to (or in) the one or more bony structures, and the proper bone fixation plate  10  has been selected (and/or reconfigured to meet anatomical needs), the bone fixation plate  10  can be positioned near and the openings in the plate  10 . One opening of the plate  10  can align with the first screw  20   a , while a second opening of the plate  10  including a carriage  40  can be aligned with the proximal end  21  of a second screws  20   b . The carriage  40  in the bone fixation plate  10  can be moved in the bone fixation plate  10  along the longitudinal axis of the bone fixation plate  10  to provide appropriate spacing, if necessary. After proper alignment of the bone fixation plate  10  to the bone screws  20   a  and  20   b , the bone fixation plate  10  (including the carriage  40 ) can be moved toward and mounted on the bone screws  20 , such that the locking device receiving hole  12  of the posterior surface  18  of bone positioning plate  10  mounts over and on to the proximal end  21  of the first bone screw  20   a  and the locking device receiving hole of the carriage  40  mounts over and on to the proximal end  21  of the second bone screw  20   b . As noted earlier, guide wires  29  can be provided (e.g., shown in  FIG. 7B ) to facilitate easier alignment of the screws  20  to the openings in the plate  10  and carriage  40 . 
         [0072]    After the bone fixation plate  10  is mounted on the first and second bone screws  20 , one or more locking devices  30  can be threaded onto the proximal end  21  of the first bone screw  20   a  and then onto the proximal end  21  of the second bone screw  20   b . This can be accomplished by taking a first locking device  30   a  and fastening it to the first bone screw  20   a , and then reducing it into the plate  10  (or carriage  40 ) by turning the locking device  30   a  until it securely engages and locks to the plate  10  (or carriage  40 ). Similarly, a second locking device  30   b  can be fastened to the remaining screw  20   b  and then reduced into the carriage  40  (or plate  10 ) until it securely engages and locks to the carriage  40  (or plate  10 ). In some embodiments, the spacing between the carriage  40  and opening  12  in the plate  10  can be adjusted after one of the screws  20  has been secured and locked to the carriage  40  (or plate  10 ), but before the remaining screw  20  has been locked to the plate  10  (or carriage  40 ). 
         [0073]    The first and second bone screws  20  can be screwed into one or more bony structures at an angle that is (in some embodiments), e.g., between about 0° and 25° away from the axis normal to the plane of the plate  10 . Because the screws  20  are not constrained to being inserted at an angle that is perfectly perpendicular to the longitudinal axis A-A of the plate  10 , the screws  20  can be closely spaced without interfering with one another. In some embodiments, the first and second bone screws  20  can be inserted into, e.g., adjacent vertebrae. 
         [0074]    As noted earlier, the proximal end  21  of the first and second bone screws  20  can comprise an open-ended guide wire capture slot to accommodate the guide wire  29 . Guide wires  29  can be inserted into the open-ended guide wire capture slots of the screws  20  after the distal end  23  of each of the screws  20  are screwed into the one or more bony structures. 
         [0075]    One or more than one carriage  40  can be mated with the carriage receiving slot  14  of the plate  10 . When only one carriage  40  is mated with the carriage receiving slot  14  of the plate  10 , the plate  10  is a single-level plate. When more than one carriage  40  is mated with the carriage receiving slot  14  of the plate  10 , the plate  10  is a multi-level plate. 
         [0076]    While the invention has been described in terms of exemplary embodiments, those skilled in the art will recognize that the invention can be practiced with modifications in the spirit and scope of the appended claims. These examples given above are merely illustrative and are not meant to be an exhaustive list of all possible designs, embodiments, applications or modifications of the invention.