Abstract:
An orthopedic fixation system includes a compression plate member, a lag screw member, and a plurality of threaded screw members for applying compression across a fracture site. The compression plate member has a generally planar body, an upper surface, and bone contacting surface. The planar body includes a plurality of through-apertures and a hinged tab member having an elongated through aperture, which is adapted to receive the lag screw member and cause the tab member to recess towards a bone divot formed in the underlying bone. The compression plate member is also adapted to receive the plurality of screw members within the through-apertures for fixably and threadably coupling the compression plate member across a fracture site. The lag screw member applies a direct compressive force across the fracture site through the deformable tab that is recessed in the bone divot.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This non-provisional application claims the benefit of provisional application No. 61/340,613, filed Mar. 19, 2010, which is herein incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to the field of orthopedic implant devices and, particularly, to an orthopedic compression plate and screw assembly for providing a direct compressive force across a fracture site to secure two or more bone fragments or bones together. 
       BACKGROUND OF THE INVENTION 
       [0003]    Orthopedic implant devices are often used to repair or reconstruct bones and joints caused by bone fractures, degenerative bone conditions, or other similar types of injuries. Frequently, these orthopedic devices require that bone fragments, due to bone fractures or bones cut by a surgical operation (i.e., an osteotomy), must be kept together for long periods of time or short periods intraoperatively under a sustained force across the fractures site in order to promote healing and stabilizing the bone fragments. As such, these orthopedic implant devices have several functions. These devices may be used to realign bone segments, to apply interfragmental compression to bone fragments, or to restore native geometries. 
         [0004]    For example, most orthopedic implants are constructed from one-piece or two-piece members and comprise threaded screws for attaching these implant devices to bone fragments. In addition, these orthopedic implant devices are constructed from standard materials, which undergo normal elastic-plastic mechanical responses during tightening. These orthopedic implants apply initial interfragmental compression, however, due to the biological conditions of bone resorbtion (i.e., removal of bone), which may be sometimes caused from micromotion across lines of fracture, interfragmental compression is lost as implants loosen due to the resorbtion of fragmental contacting surfaces, thereby causing the fragments or device to shorten. This biological condition eliminates ideal conditions for bone healing, as stated by Wolff&#39;s law: bone grows under load and resorbs (i.e. removed) in the lack of loads. Thus, these orthopedic implant devices are not very effective in maintaining interfragmental compression for long periods as is required in order to heal the fracture site. 
         [0005]    Other devices utilize deformable compression staples or deformable compression plate and screw constructs that provide compression by using a tool to deform and shorten the length of the compression staples or plates. Yet, these too are inefficient, as these staple or plate constructs do not apply the required compression across the fracture site needed to hold and compress the bone fragments. In addition, implant loosening is a serious concern and is commonly caused by one or multiple conditions, such as subsidence, centering, fixation loosening or cortical failure to name a few. 
         [0006]    There is, therefore, a need for an orthopedic implant device assembly and a method of use for the orthopedic implant device assembly that overcomes some or all of the previously delineated drawbacks of prior orthopedic implant device assemblies. 
       SUMMARY OF THE INVENTION 
       [0007]    An object of the invention is to overcome these and other drawbacks of previous inventions. 
         [0008]    Another object of the invention is to provide a novel and useful orthopedic fixation assembly that may be utilized to secure multiple bones fragments or bones together. 
         [0009]    Another object of the invention is to provide an orthopedic fixation assembly that may be utilized to secure the implant bone interface. 
         [0010]    Another object of the invention is to provide an orthopedic fixation assembly for facilitating direct compression across the fracture site. 
         [0011]    Another object of the invention is to provide an orthopedic fixation assembly having a plate and screw construct for preventing rotation of the adjacent constructs. 
         [0012]    Another object of the invention is to provide a hybrid orthopedic fixation assembly for applying direct compression through a hinge-like mechanism. 
         [0013]    Another object of the invention is to provide a fixation assembly having a hybrid plate member that accepts a variable angle screw in order to provide a compound variable angle construct. 
         [0014]    In a first non-limiting embodiment of the invention, a compression plate for orthopedic fixation is provided and includes a coplanar body portion having an upper surface and a directly opposed bone contacting surface. The body portion includes a longitudinal axis. The compression plate has a plurality of bone screw holes extending orthogonally through the upper and bone contacting surfaces, with each of the bone screw holes configured for receiving a bone screw. Finally, the compression plate has a generally rectangular tab member residing within an elongated slot in the body portion. 
         [0015]    In a second non-limiting embodiment of the invention, an orthopedic fixation system for bone fusion includes a compression plate having a body portion, with the body portion having an upper surface, a directly opposed bone contacting surface, a plurality of bone screw holes, and a generally rectangular tab member residing within an elongated slot in said body portion. The body portion has a first section defining a first longitudinal axis, and a second section defining a second longitudinal axis. The plurality of bone screw holes extend orthogonally through the upper and bone contacting surfaces. The system further includes a plurality of threaded bone screws that are configured to be received in the compression plate. 
         [0016]    In a third non-limiting embodiment of the invention, an orthopedic fixation assembly is provided and includes a compression plate member, a lag screw member, and a plurality of threaded screw members for applying compression across a fracture site. The compression plate member has a generally planar body and a first exposed surface and a second opposed surface. The planar body includes a plurality of through apertures and a hinged tab member having an elongated through aperture, which is provided to receive the lag screw member. The tab member recesses in a bone divot formed in the underlying bone. The compression plate member receives the plurality of screw members within the through apertures in order to fixably couple the compression plate member across a fracture site. The lag screw member applies a direct compressive force across the fracture site through the deformable tab being recessed in the bone divot. 
         [0017]    In a fourth non-limiting embodiment of the invention, a method for inserting an orthopedic fixation assembly into bone fragments is provided and includes several non-limiting steps. In one step, a Kirschner wire inserted at a desired trajectory angle into the human foot. The Kirschner wire is coupled to a standard drill and inserted into the calcaneus bone and cuboid bone at a desired trajectory, which represents the desired trajectory of a lag screw member. The position of the inserted Kirschner wire may be verified through fluoroscopy and its position inside cuboid bone may be adjusted so that the tapered end of Kirschner wire resides at a desired depth. Next, in another step, the Kirschner wire is coupled to a cannulated drill and a pilot hole is drilled into the cuboid bone to a desired depth at predetermined trajectory of the Kirschner wire. The depth of the pilot hole is determined based on the desired length of the lag screw. Next, another step, a cannulated countersink drill is inserted over the Kirschner wire and drilled into the surface of calcaneus bone in order to create a bone divot for a hinged tab member. The recommended depth of bone divot is determined by marking the countersink drill and drilling into the surface of the calcaneus bone to this depth. The Kirschner wire is removed from the cuboid and calcaneus bones after countersinking. Next, in another step, a threaded screw member is inserted into the compression plate member in one side of the joint or fracture site. The compression plate member may be selected so that the desired length of the plate member will span across the fusion site and leave an adequate length between the opposed threaded screws. A pilot hole is predrilled into the bone and a threaded screw member is inserted into the pilot hole. The threaded screw member provides retention of the compression plate member into bone and locks the compression plate member for receiving the other threaded screw members. Next, in another step, lag screw member is inserted into the elongated aperture of compression plate member through the created trajectory. The lag screw member will deform the tab member towards the surface of the calcaneus bone and the tab will recede into the bone divot while the lag screw member is driven across the joint and compression is established. The lag screw member is driven into the joint until satisfactory compression is achieved. The position of the inserted lag screw member may be verified through fluoroscopy and its position inside joint may be adjusted so that the lag screw member resides at a desired depth. Next, in another step, pilot holes are predrilled into the unused apertures of the compression plate member and the remaining threaded screw members are inserted into these holes in order to threadably couple the compression plate member to the bone. The position of the inserted screw members may be verified through fluoroscopy. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    A further understanding of the invention can be obtained by reference to a preferred embodiment set forth in the illustrations of the accompanying drawings. Although the illustrated embodiment is merely exemplary of systems and methods for carrying out the invention, both the organization and method of operation of the invention, in general, together with further objectives and advantages thereof, may be more easily understood by reference to the drawings and the following description. The drawings are not intended to limit the scope of this invention, which is set forth with particularity in the claims as appended or as subsequently amended, but merely to clarify and exemplify the invention. 
           [0019]    For a more complete understanding of the invention, reference is now made to the following drawings in which: 
           [0020]      FIG. 1  is a perspective view of an orthopedic fixation assembly inserted into the bones of a patient&#39;s foot according to the preferred embodiment of the invention. 
           [0021]      FIG. 2  is another perspective view of the orthopedic fixation assembly that was shown in  FIG. 1 . 
           [0022]      FIG. 3  is a perspective view of the hinged tab member, which was shown in  FIGS. 1 and 2  according to the preferred embodiment of the invention. 
           [0023]      FIG. 4  illustrates a surgical step of inserting the orthopedic fixation assembly of  FIG. 1  using a Kirschner wire according to the preferred embodiment of the invention. 
           [0024]      FIG. 5  illustrates another surgical step of installing the orthopedic fixation assembly of  FIG. 1  using a countersink drill according to the preferred embodiment of the invention. 
           [0025]      FIG. 6  illustrates another surgical step of installing the orthopedic fixation assembly of  FIG. 1  using the screw members according to the preferred embodiment of the invention. 
           [0026]      FIG. 7  is a perspective view of the assembled orthopedic fixation assembly inserted into the calcaneus and cuboid bones of a patient&#39;s foot according to an embodiment of the invention. 
           [0027]      FIG. 8  is a flow chart illustrating the surgical method of coupling the orthopedic fixation assembly shown in  FIGS. 1-7  to the calcaneus and cuboid bones in a patient&#39;s foot according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    The invention may be understood more readily by reference to the following detailed description of preferred embodiment of the invention. However, techniques, systems, and operating structures in accordance with the invention may be embodied in a wide variety of forms and modes, some of which may be quite different from those in the disclosed embodiment. Consequently, the specific structural and functional details disclosed herein are merely representative, yet in that regard, they are deemed to afford the best embodiment for purposes of disclosure and to provide a basis for the claims herein, which define the scope of the invention. It must be noted that, as used in the specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly indicates otherwise. 
         [0029]    Referring now to  FIGS. 1-2 , there is shown an orthopedic fixation assembly  100  which is made in accordance with the teachings of the preferred embodiment of the invention. As shown, orthopedic fixation assembly  100  comprises a generally coplanar compression plate member  110 , which is provide to selectively receive a plurality of threaded screws  115 ,  120 ,  125 , and a threaded lag screw  130 . In the preferred embodiment, threaded lag screw  130  is a variable angle screw. The lag screw  130  is received in plate member  110  and cooperates with compression plate member  110  in order to selectively apply compression across the bone fracture site in the human foot  145 . In another non-limiting embodiment, the threaded lag screw  130  may be a fixed angle screw incorporating a Morse taper lock. Also, threaded screws  115 ,  120 , and  125  may be fixed angle screws, variable angle screws, or a combination of fixed and variable angle screws depending on the needs of a surgeon. It should be appreciated that the orthopedic fixation assembly  100  is provided to be inserted across any bone or through a plurality of bones, such as in one non-limiting example, the calcaneus bone  135  and the cuboid bone  140  in the human foot  145 , although in other embodiments, the orthopedic fixation assembly  100  is provided to be inserted into substantially any other bones or parts of bones. It should also be appreciated that the orthopedic fixation assembly  100  may be utilized for the reconstruction and fusion of joints of the extremities in order to apply direct and evenly distributed compression across the joint or fracture site or on the bones in the foot  145 . 
         [0030]    Also, as shown in  FIG. 3 , compression plate member  110  has a generally coplanar body  300  from a first end  305  to a second end  310  (i.e., body  300  has a constant thickness from first end  305  to second end  310 ). Body  300  includes a plurality of transverse apertures  315 ,  320 , and  325 , which are provided at first end  305  and second end  310  respectively (i.e., aperture  315  is provided at first end  305  and apertures  320 ,  325  are provided at second  310 ). The plurality of apertures  315 ,  320 , and  325  traverse the surfaces of body  300  (i.e., penetrate body  300 ) from first surface  330  to opposed second surface  335 . The apertures  315 ,  320 , and  325  are provided to receive a plurality of screws  115 ,  120 , and  125  respectively (shown in  FIGS. 1-2 ) in order to couple the compression plate member  110  to the bones in the human foot  145  (shown in  FIGS. 1-2 ) or other similar bones. Threaded screws  115 ,  120 , and  125  may be fixed angle screws, variable angle screws, or a combination of fixed and variable angle screws depending on the needs of a surgeon. In other non-limiting embodiments, variable angle screws or locking fixed or variable angle screws having a Morse taper lock between the screw head and the apertures  315 ,  320 , and  325  may be utilized for any of the screws  115 ,  120 , and  125 . 
         [0031]    Additionally, compression plate member  110  has a hinged tab member  340  formed in body  300 . Particularly, hinged tab member  340  is generally rectangular in shape and includes a plurality of channels  345 ,  350 , and  355  formed along the three edges of tab member  340 . Particularly, tab member  340  has channel  345  formed along edge  360 , channel  350  formed along edge  365 , and channel  355  formed along edge  370 . Fourth edge  375  includes a hinge formed in groove  380  recessed along length of edge  375 , hingedly coupled to plate member  110 , and generally coextensive with length of edge  375 . Channels  345 ,  350 , and  355  cooperate with hinge to cause tab member  340  to bend (or flex) along the hinge formed by groove  380  along edge  375  and body  300 , at a multitude of angles upon application of force on tab member  340 . It should be appreciated that tab member  340  cooperates with a variable angle lag screw  130  (shown in  FIGS. 1-2 ) to provide a compound variable angle for positioning the tab member  340  on the bone surface, causing the lag screw  130  to provide compression across the fracture site or joint while the plate member  110  maintains the compressed position of the bones. 
         [0032]    Also, hinged tab member  340  includes aperture  385  for receiving a threaded lag screw  130  (shown in  FIGS. 1-2 ). The aperture  385  is generally elongated in shape and traverses the surface of body  300  (i.e., penetrates body  300 ) from first surface  330  to opposed second surface  335 . The aperture  385 , being elongated, allows for various  385  or variable angle screws to be inserted into aperture  385  at various angles of fixation. It should be appreciated that aperture  385  is provided to cooperate with lag screw  130  (shown in  FIGS. 1-2 ) to deform tab member  340  towards the surface of the underlying bone, thereby facilitating application of compression across the joint or fracture site. It should also be appreciated that the tab member  340  may recess into a dimple created on the underlying bone surface to facilitate additional purchase of the lag screw  130  into bone. It should also be appreciated second surface  335  of plate member  110  may be coated with an osteoconductive material, such as, for example, plasma spray or other similar types of porous materials that is capable of supporting or encouraging bone ingrowth into this material. 
         [0033]    In operation, and as best shown in FIGS.  1  and  4 - 8 , the orthopedic fixation assembly  100  may be utilized for osteotomies and arthrodeses of the foot  145  by connecting and compressing the damaged bones in order to promote healing. In other non-limiting embodiments, the orthopedic fixation assembly  100  may also be utilized to apply compression to the other bones in the human body. In one example shown in  FIG. 1 , the orthopedic fixation assembly  100  may be coupled to the calcaneus bone  135  and the cuboid bone  140  in order to provide direct compression and stability across the fracture site of the joint connecting the calcaneus bone  135  to the cuboid bone  140 . 
         [0034]    As shown in  FIGS. 4-8 , the orthopedic fixation assembly  100  may be utilized for, in one non-limiting embodiment, the internal fixation of bone or bone fragments in the human foot  145  ( FIG. 1 ). As shown, the method starts in step  800  and proceeds to step  802 , whereby a Kirschner wire  400  is inserted at a desired trajectory angle into the human foot  145  ( FIG. 1 ). In this step, a Kirschner wire  400  is selected and coupled to a standard drill (not shown) and inserted into the calcaneus bone  135  and cuboid bone  140  at a desired trajectory, which represents the desired trajectory of the lag screw  130  ( FIG. 1 ). The position of the inserted Kirschner wire  400  may be verified through fluoroscopy and its position inside cuboid bone  140  may be adjusted so that the tapered end of Kirschner wire  400  resides at a desired depth. Next, in step  804 , the Kirschner wire  400  is coupled to a cannulated drill and a pilot hole is drilled into the cuboid bone  140  ( FIG. 4 ) to a desired depth at predetermined trajectory of the Kirschner wire  400 . The depth of the pilot hole is determined based on the desired length of the lag screw  130  (shown in  FIG. 1 ). Next, in step  806 , a cannulated countersink drill  500  (shown in  FIG. 5 ) is inserted over the Kirschner wire  400  and drilled into the surface of calcaneus bone  140  in order to create a bone divot for hinged tab member  340  (shown in  FIG. 3 ). The recommended depth of bone divot is determined by marking the countersink drill  500  and drilling into the surface of the calcaneus bone  135  to this depth. The Kirschner wire  400  is removed from the bones  135  and  140  after countersinking. Next in step  808 , threaded screw member  115  is inserted into the compression plate member  110  in one side of the joint or fracture site. The compression plate member  110  (shown in  FIG. 6 ) may be selected so that the desired length of the plate member  110  will span across the fusion site and leave an adequate length between the opposed threaded screws. A pilot hole is predrilled into aperture  315  ( FIG. 3 ) and a threaded screw member  115  is inserted into the aperture  315  and into the pilot hole. The threaded screw member  115  provides retention of the compression plate member  110  into bone  135  and locks the compression plate member  110  for receiving the other threaded screw members. Next, in step  810 , lag screw member  130  is inserted into the elongated aperture  385  ( FIG. 3 ) of compression plate member  110  through the created trajectory. The lag screw member  110  will deform the tab member  340  towards the surface of the calcaneus bone  135  and the tab will receded into the bone divot while the lag screw member  130  is driven across the joint and compression is established. The lag screw member  130  is driven into the joint until satisfactory compression is achieved. The position of the inserted lag screw member  130  may be verified through fluoroscopy and its position inside joint may be adjusted so that the lag screw member  130  resides at a desired depth. Next, in step  812 , pilot holes are predrilled into apertures  320  and  325  (shown in  FIG. 3 ) and the remaining threaded screw members  120 ,  125  (shown in  FIG. 7 ) are inserted into their respective holes  320 ,  325  ( FIG. 3 ) in order to threadably couple the compression plate member  110  to the cuboid bone  140  (Shown in  FIG. 7 ). The position of the inserted screw members  120 ,  125  may be verified through fluoroscopy. The method ends in step  814 . 
         [0035]    It should also be understood that this invention is not limited to the disclosed features and other similar method and system may be utilized without departing from the spirit and the scope of the invention. 
         [0036]    While the invention has been described with reference to the preferred embodiment and alternative embodiments, which embodiments have been set forth in considerable detail for the purposes of making a complete disclosure of the invention, such embodiments are merely exemplary and are not intended to be limiting or represent an exhaustive enumeration of all aspects of the invention. The scope of the invention, therefore, shall be defined solely by the following claims. Further, it will be apparent to those of skill in the art that numerous changes may be made in such details without departing from the spirit and the principles of the invention. It should be appreciated that the invention is capable of being embodied in other forms without departing from its essential characteristics.