Abstract:
A modular bone plating system in one embodiment is a bone plate kit including a plurality of bone plates, each of the plurality of bone plates including a male coupling portion, a female coupling portion and a shaft extending between the male coupling portion and the female coupling portion, wherein each of the male coupling portions of each of the plurality of bone plates is configured to couple with each of the female coupling portions of each of the other of the plurality of bone plates.

Description:
FIELD OF THE INVENTION 
     This invention relates to the field of orthopaedics and more particularly to methods and instrumentation used in orthopaedic procedures. 
     BACKGROUND 
     A bone plate is a hard, normally metallic plate that is configured for attachment to bone surfaces, across bone fragments or across areas of bone reconstruction. The bone plate is used to provide stability to those areas and may further be used to compress and immobilize those areas so as to facilitate rebuilding and mending of the bones. Typically, a bone plate is an elongated strip with a number of openings located at regular intervals for attachment of the bone plate to a bone using bone screws. The surfaces of the strip may be contoured, textured or otherwise formed to facilitate secure placement on a bone surface. 
     Some bone plates, such as compression plates, are positioned tightly against the outer surface of the bone. Accordingly, to provide proper distribution of loads between the bone and the bone plate, the bone plate should be closely conformed to the bone contours. The contours of the bones to which bone plates are attached, however, vary from individual to individual. Accordingly, maintaining an inventory of bone plates which are specially formed for an individual or even a group of individuals is cost prohibitive. 
     One type of bone plate that has been developed in response to problem of providing a bone plate that is properly shaped, is a reconstruction bar. Reconstruction bars are formed from a biocompatible material that can be bent using special tools during a surgery. Typically, the surgeon forms by hand a thin metal template of the specific bone contour at the desired implantation cite. This process is generally performed after an incision has been made to expose the implantation location and the metal template is physically placed against the patient&#39;s bone. 
     Once a template is formed, the surgeon uses the special tools to shape the reconstruction bar to visually match the metal template. A number of tools have been developed to assist in reshaping the bone plates. The tools include are bending irons, specially adapted pliers, and bench-mounted bending presses that will bend a plate between a pair of anvils, one anvil having a single contact point, and the opposite anvil having a spaced pair of contact points. The shaped reconstruction bar is then attached to the bone using bone screws. Therefore, in addition to the expense of the special tools, this process can be time consuming and require a high level of skill to achieve an acceptably shaped bone plate. 
     Moreover, the shaped bone plate will generally not conform exactly to the surface of the bone at the attachment location. Thus, tightening of the bone plate against the bone with the bone screws induces bending preloads on the bone plate resulting in spring-back due to the resilient properties of the bone plate. Additionally, gaps may be present between the bone plate and the bone resulting in an uneven transfer of load from the plate to the bone. Consequently, the bone screw may break or strip away from the bone resulting in loss of fracture reduction, bone misalignment, extended healing time or corrective surgeries. 
     Therefore, a need exists for a bone plate that can easily be conformed to the shape of a patient&#39;s bone. A further need exists for a bone plate that does not require a large number of special tools and which is easy to manufacture. 
     SUMMARY 
     Orthopaedic instrumentation and a method of manufacturing the instrumentation is disclosed. In one embodiment, a modular bone plate includes a male snap-fit coupling portion, a female snap-fit coupling portion, and a shaft extending between the male coupling portion and the female coupling portion, the shaft including a bottom bone contacting surface and an upper surface opposite the bone contacting surface. 
     In a further embodiment a bone plate kit includes a plurality of bone plates, each of the plurality of bone plates including a male coupling portion, a female coupling portion and a shaft extending between the male coupling portion and the female coupling portion, wherein each of the male coupling portions of each of the plurality of bone plates is configured to couple with each of the female coupling portions of each of the other of the plurality of bone plates. 
     A method of constructing a bone plate includes aligning a male coupling portion of a first bone plate module with a female coupling portion of a second bone plate module, compressing a taper of the male coupling portion, inserting the compressed taper into the female coupling portion, rigidly coupling the first bone plate module with the second bone plate module, placing the rigidly coupled first bone plate module and second bone plate module on the surface of a bone, inserting a portion of a fastener through the male coupling portion and attaching the rigidly coupled first bone plate module and second bone plate module to the surface of a bone with the fastener 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a perspective view of a bone plate module with a male coupling portion and a female coupling portion in accordance with principles of the present invention; 
         FIG. 2  depicts a cross-sectional view of the bone plate module of  FIG. 1 ; 
         FIG. 3  depicts a top plan view of the bone plate module of  FIG. 1  that can be coupled with another bone plate module; 
         FIG. 4  depicts a perspective view of a bone plate module that can be coupled with the bone plate module of  FIG. 1 ; 
         FIG. 5 . depicts a top plan view of the bone plate module of  FIG. 1  coupled with the bone plate module of  FIG. 4  to form a straight portion of a bone plate; 
         FIG. 6  depicts a partial cross sectional view of the bone plate module of  FIG. 1  coupled with the bone plate module of  FIG. 4   
         FIG. 7  depicts the bone plate modules of  FIG. 4  and  FIG. 1  coupled together to form an angled portion of a bone plate; 
         FIG. 8  depicts a top plan view of the angled bone plate modules of  FIG. 7 ; 
         FIG. 9  depicts a top plane view of the bone plate modules of  FIG. 4  and  FIG. 1  coupled together to form a portion of a bone plate that is angled more than the angled portion shown in  FIG. 8 . 
         FIG. 10  depicts the bone plate modules of  FIG. 4  and  FIG. 1  rigidly coupled together to form an angled portion of a bone plate with a fastener inserted through the male coupling portion of one bone plate module and another fastener inserted through the female coupling portion of the second bone plate modules and through a male end cap. 
         FIG. 11  depicts the end cap of  FIG. 10 ; 
         FIG. 12  depicts a female end cap that may be used with the male coupling portion of the bone plate module of  FIG. 1 ; 
         FIGS. 13 and 14  show views of a decoupler that may be used to decouple two rigidly coupled bone plate modules; 
         FIG. 15  depicts the decoupler of  FIGS. 13 and 14  positioned along the shaft of the bone plate module shown in  FIG. 1  so as to decouple the bone plate modules of  FIG. 4  and  FIG. 1 ; and 
         FIGS. 16-21  depict various alternative configurations of bone plate modules with coupling portion in accordance with principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a bone plate module  100 . The bone plate module  100  includes a shaft  102  extending between two end portions  104  and  106 . A male coupling portion  108  is positioned at the end portion  104  and a female coupling portion  110  is positioned at the end portion  106 . Two notches  112  and  114  are located on the end portion  104  next to the male coupling portion  108 . The end portion  104  terminates at a curved outer perimeter  116  and the end portion  106  terminates at a curved outer perimeter  118 . 
     The male coupling portion  108  includes a taper  120  which extends upwardly from a plateau  122 . A ridge  124  extends around the perimeter of and outwardly from the taper  120 . Two slots  126  and  128  are formed in the taper  120  and the ridge  124 . The inner surface  130  of the taper  120  curves downwardly and inwardly to a threaded portion  132  as shown in  FIG. 2 . 
     Two rotation stops  134  and  136  are located at one end of the shaft  102  near the male coupling portion  108 . Referring to  FIG. 3 , the shaft  102  includes side walls  138  and  140  which extend from the end portion  104  to the end portion  106 . An inwardly curved wall  142  is located at the end of the shaft  106  nearest the end portion  104  and extends downwardly from the upper surface  144  of the bone plate module  100 . Another inwardly curved wall  146  which is located at the end of the shaft  106  nearest the end portion  106  extends upwardly from the bottom surface  148  of the bone plate module  100 . 
     The female coupling portion  110  includes a bore  150  which extends downwardly from the upper surface  144  and opens to an overhang  152 . The overhang  152  is located between the curved wall  146  and the outer perimeter  118 . A groove  154  extends about the perimeter of the bore  150 . 
     The bore  150  is sized to be slightly smaller in diameter than the diameter of the taper  120 . The groove  154 , which is sized complementary to the ridge  124 , is located at a distance away from the opening of the bore  150  to the overhang  152  that is about the same a as the distance at which the ridge  124  is positioned on the taper  120  above the plateau  122 . Additionally, the curvature of the inwardly curved wall  146  is complementary to the curvature of the outer perimeter  116  and the curvature of the inwardly curved wall  142  is complementary to the curvature of the outer perimeter  118 . 
     The complementary configuration of the end portion  104  and the end portion  106  along with the configuration of the male coupling portion  108  and the female coupling portion  110  allow two or more bone plate modules like the bone plate module  100  to be rigidly coupled. By way of example,  FIG. 4  shows a bone plate module  200  which is identical to the bone plate module  100  in all respects. The bone plate module  100  and the bone plate module  200  may be rigidly coupled as shown in  FIG. 5 . 
     Coupling of the bone plate module  100  with the bone plate module  200  to obtain the bone plate  156  shown in  FIG. 5  is accomplished by aligning the male coupling portion  202  of the bone plate module  200  with the female coupling portion  110  of the bone plate module  100 . The male coupling portion  202  and the female coupling portion  110  are then pressed together. The diameter of the bore  150  is slightly smaller than the diameter of the taper  204 . Accordingly, the taper  204  is placed under a compressive force. 
     The bone plate module  200  is made from a biocompatible material. Such materials include stainless steel, titanium alloy and polymers. These materials exhibit some amount of flexibility when formed with a thin cross section. Thus, the thin walls of the taper  204 , particularly at the upper portion of the taper  204 , allow the taper  204  to flex inwardly. Moreover, the slots  206  and  208  allow additional flexure. Depending upon the materials used and the particular design, more, fewer or even no slots may be incorporated. 
     Inward flexure of the taper  204  allows the taper  204  to slide into the bore  150 . As the ridge  210  contacts the opening of the bore  150  to the overlap  152 , additional force is required to flex the taper  204  farther in the inward direction so that the ridge  210  can enter into the bore  150 . As the taper  204  is inserted more fully into the bore  150 , the ridge  210  aligns with the groove  154 . The increased diameter of the groove  154  compared to the remainder of the bore  150  allows the taper  204  to flex outwardly, thereby forcing the ridge  210  into the groove  154  resulting in the configuration shown in  FIG. 6 . 
     In  FIG. 6 , the ridge  210  is located within the groove  154  and the portion of the bone plate module  100  between the bore  150  and the outer perimeter  118  fits within the gap between the taper  204  and the inwardly curved wall  212 . Additionally, the overhang  152  rests upon the plateau  214  and the outer perimeter  216  is adjacent to the inwardly curved wall  142 . Additionally, the bottom surface  218  of the bone plate module  200  is aligned with the bottom surface  148  of the bone plate module  100 . Accordingly since the snap-fit provided in this embodiment results in a rigid connection between the module  100  and the module  200 , the combination of the bone plate module  100  and the bone plate module  200  provides a single straight bone plate  156 . 
     As described above, the curvature of the inwardly curved wall  146  is complementary to the curvature of the outer perimeter  116  and the curvature of the inwardly curved wall  142  is complementary to the curvature of the outer perimeter  118 . Thus, since the bone plate module  200  is identical to the bone plate module  100 , the bone plate modules  100  and  200  may be coupled at an angle to each other. As shown in  FIGS. 7 and 8 , the bone plate modules  100  and  200  may be used to build an angled bone plate  158 . This is accomplished by aligning the male coupling portion  202  of the bone plate module  200  with the female coupling portion  110  of the bone plate module  100  such that the longitudinal axis  161  of the plate  100  is set at the angle α with respect to the longitudinal axis  220  of the plate  200  and then pressing the bone plate modules  100  and  200  together in the manner discussed above with respect to the bone plate  156 . 
     The bone plate modules  100  and  200  are not constrained to forming a bone plate with a single angle. For example, in the bone plate  160  shown in  FIG. 9 , the longitudinal axis  162  of the plate  100  is set at an angle β with respect to the longitudinal axis  220  of the plate  200  that is larger than the angle α. The range of angles which can be formed in this embodiment is limited in one direction by the rotation stop  222  which impinges on the side wall  140  and in the other direction by the rotation stop  224  which impinges on the side wall  138 . 
       FIG. 10  shows a bone plate  170  that includes bone plate modules  100  and  200  and a male end cap  178 . The bone plate  170  may be fastened to a bone using bone screws  172  and  174 . The bone screw  172  is inserted through the taper  120 . The head  176  of the bone screw  172  may be threaded to engage the threaded portion  132  of the taper  120 . The threaded portion  132  may be triple lead threaded to provide for use of both locking and non-locking screws. A compression screw may be used either with or without a threaded portion  132 . 
     The screw  174  extends through the bore  226 . The bore  226 , however, has no threads to engage the screw  174 . The male end cap  178 , however, is threaded as shown in  FIG. 11 . Specifically, the male end cap  178  includes a male coupling portion  180  with a threaded portion  182  that extends upwardly from a plateau  184 . Two notches  186  and  188  are provided in the plateau  184 . A base  190  includes a bottom that is formed in like manner to the bottom surface  148  of the bone plate  100 . 
     The base  190  has a curved outer perimeter portion  192  that is substantially identical to the outer perimeter  118  and another curved outer perimeter portion  194  that is complementary to the inwardly curved wall  146 . Thus, when the male end cap  178  is installed as shown in  FIG. 10 , the end portion of the bone plate module  200  is supported as if the bone plate module  200  were coupled with the male coupling portion of another bone plate module. Additionally, the bottom surface of the bone plate  170  provides a uniform contact surface from one end of the plate  170  to the opposites end. 
       FIG. 12  shows a female end cap  240  that may be used with the bone plate modules  100  and  200 . The female end cap  240  includes a female coupling portion  242  with a bore  244  that extends through the female end cap  240 . A groove  246  extends around the groove  246 . The female end cap  240  has a curved outer perimeter portion  248  that is substantially identical to the outer perimeter  116  and a curved outer perimeter portion  250  that is complementary to the inwardly curved wall  142 . 
     Thus, when the female end cap  240  is installed on the male coupling portion  108 , the upper surface of the bone plate  170  provides a uniform upper surface, thereby reducing the potential for irritation to soft tissue adjacent to the plate  170 . Additionally, any male coupling portions that are not filled with a screw may be filled, for example, with a threaded plug. 
     A decoupler  260  is shown in  FIGS. 13 and 14  that may be used to be decouple two bone plate modules. The decoupler  260  includes a shaft  262  and a yoke  264 . Two stubs  266  and  268  are provided on arms  270  and  272 , respectively. The arms  270  and  272  are spaced apart by a distance which is approximately equal to the width of the bone plate module. The stubs  266  and  268  are canted with respect to the shaft  262  and are sized slightly smaller than the notches of the bone plate module with which the decoupler  260  is to be used. 
     Operation of the decoupler  260  is explained with further reference to  FIG. 15 . In this example, the decoupler  260  will be used to decouple the bone plate  180  which was formed by coupling the bone plate modules  100  and  200 . Initially the decoupler  260  is placed generally perpendicularly to the bone plate module  100  and the yoke  264  moved toward the upper surface  144  of the bone plate module. As noted above, the arms  270  and  272  are separated by about the same distance as the width of the bone plate module  100 . Accordingly, the distance between the stubs  266  and  268  is shorter than the width of the bone plate module  100 . Therefore, pushing the yoke- 1 - 64   264  toward the bone plate module  100  forces the stubs  266  and  268  against the bone plate module  100  causing the arms  270  and  272  to flex apart thereby allowing the stubs  266  and  268  to slide along sidewalls  138  and  140 . 
     As the stubs  266  and  268  approach the notches  114  and  112 , the shaft  262  is moved toward a more parallel position with respect to the bone plate module  100 . This movement brings the canted stubs  266  and  268  into alignment with the notches  114  and  112 . Once aligned the yoke  264  flexes toward its original shape thereby forcing the stubs  266  and  268  into the notches  114  and  112 , respectively. The cant of the stubs  266  and  268  with respect to the shaft  262  ensures that the stubs  266  and  268  enter the notches  114  and  112  before the shaft  262  of the decoupler  260  is in contact with the upper surface  144  of the bone plate module  100 . 
     Additionally, the arms  270  and  272  are sized such that as the stubs  266  and  268  enter the notches  114  and  112 , the yoke  264  is close to, if not touching, the upper surface  144  of the bone plate module  100 . Application of force to the shaft  262  thus causes the yoke  264  to contact the bone plate module  100  and provide a pivot point for the decoupler  260 . Pressure on the shaft  262  thus forces the stubs  266  and  268  against the female coupling portion of the bone plate module  200  thereby forcing the groove of the bone plate  200  against the ridge  124  thereby flexing the taper  120  inwardly. As the ridge  124  exits the groove of the bone plate module  200 , the bone plate module  200  may be lifter clear of the bone plate module  100 . 
     A kit may include a number of bone plate modules, male end caps, female end caps and a decoupler. Additionally, a template may be provided to assist the surgeon in determining the desired number and orientation of bone plate modules to be used to form a bone plate. In one embodiment, bone plate modules are provided in various lengths. For example, one group of bone plate modules may have a length of about 25 millimeters while a second group has a length of about 30 millimeters, and additional groups may have larger lengths. A bone plate module with a length of about 25 millimeters provides sufficient length to incorporate both a male and a female coupling portion of a size that provides a robust coupling force to obtain a bone plate with the desired rigidity. 
       FIGS. 16-21  show various bone plate modules that may be provided either separately or in a kit with other bone plate modules.  FIG. 16  shows a “Y” shaped bone plate module  300  that includes two female coupling portions  302  located at end portions  304  and  306  and one male coupling portion  308  at an end portion  310 . Alternatively, the bone plate module  300  may include two male coupling portions, all female coupling portions or all male coupling portions. A shaft  312  extends between each of the end portions  304 ,  306  and  310 . 
     The end portions  304  and  306  have the same configuration as the end portion  106  and the end portion  310  has the same configuration as the end portion  104 . Likewise, the female coupling portions  302  and the male coupling portion  308  have the same configuration as the female coupling portion  110  and the male coupling portion  108 , respectively. Additionally, the shaft  312 , at each end portion  304 ,  306  and  310 , has the same configuration as the shaft  102  for the corresponding coupling portion. Thus, since the end portion  310  has a male coupling portion  308  and the end portion  104  of  FIG. 1  has a male coupling portion  108 , the shaft  312  includes an inwardly curved wall  314  at the end portion  310  that has the same configuration as the inwardly curved wall  142  of  FIG. 1 . 
     Accordingly, the bone plate module  300  may be used with the bone plate modules  100  and  200 , the male end cap  178  and female end cap  240 . Additionally, the decoupler  260  may be used with the bone plate module  300 . Finally, the bone plate modules  100 ,  200  or another bone plate module  300  may be coupled to either of the female coupling portions  302  or the male coupling portion  308  in the same manner that the bone plates  100  and  200  may be coupled together. 
     Other bone plate modules include the “S” shaped bone plate module  320  of  FIG. 17 , the “T” shaped bone module  322  of  FIG. 18  which is configured with three female coupling portions  324 , the “T” shaped bone module  326  of  FIG. 19  which is configured with three male coupling portions  328 , the curved bone plate module  330  of  FIG. 20  and the cross shaped bone plate module  332  of  FIG. 21 . Each of these bone plate modules, as well as bone plate modules of other shapes, may be configured with various combinations of coupling portions and in various sizes to allow a bone plate to be quickly and easily configured for a particular patient. 
     While the present invention has been illustrated by the description of exemplary processes and system components, and while the various processes and components have been described in considerable detail, the applicants do not intend to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will also readily appear to those ordinarily skilled in the art. The invention in its broadest aspects is therefore not limited to the specific details, implementations, or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicants&#39; general inventive concept.