Abstract:
A member of a modular bone plate is provided, the member comprising a top surface defining a top plane; a bottom surface defining a bottom plane; a connection portion including a hole with a center axis that intersects the top plane and the bottom plane; wherein a first portion of the edge of the hole is provided with a projection forming a first free end of the member and wherein a second portion of the edge of the hole is provided with a groove that is configured to accommodate a projection of a connection portion of a second member of the modular bone plate. Furthermore, a modular bone plate having at least two such members is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and wholly incorporates by reference U.S. provisional application No. 61/497,972 to Biedermann filed on Jun. 17, 2011 (Atty Docket No. MD 11-P28350US00). 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a modular bone plate and to a member of such a modular bone plate. 
       BACKGROUND OF THE INVENTION 
       [0003]    Various shapes and types of bone plates to be used for osteosynthesis of fragmented bones and for stabilization of bones are known. The shape, size and type of a bone plate are usually adapted to the bones that shall be stabilized or immobilized. Hence, a large inventory of bone plates is typically necessary to be able to treat many different kinds of fractures or other defects at different locations. 
         [0004]    There exist also modular bone plate systems that allow construction of a bone plate adapted to a specific application and to the individual patient by combining single members to form a whole bone plate. For example, US 2009/0082813 A1 describes a modular bone plating system including a 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. 
         [0005]    U.S. Pat. No. 5,484,439 describes a modular femur fixation device. The device comprises an upper side  plate with a widened head and an angled barrel, and a lower side plate adapted to be engaged with the upper side plate in a tongue and groove configuration. 
       SUMMARY OF THE INVENTION 
       [0006]    It is the object of the invention to provide a modular bone plate and a member of such a modular bone plate that is simplified in terms of handling and manufacturing while exhibiting a strength that is comparable to single part bone plates. 
         [0007]    The object and further developments are addressed by the various embodiments of the invention. 
         [0008]    The modular bone plate is assembled by connecting at least two members of the modular bone plate at their respective connection portions such that the projection of the connection portion of a first member is introduced into the groove of a connection portion of the second member. In the assembled configuration the holes of both connection portions are arranged concentrically, on top of each other. The assembly is quickly and easily performed and the resulting construct is prevented from disassembling by the form locking connection between the projection and the groove. Hence, the surgeon can take the pre-assembled bone plate and place it on to the bone parts or fragments or bones that need to be connected or stabilized without using further elements or tools for keeping together the bone plate members. 
         [0009]    Due to modularity, lower inventory may be required and it may be possible to reduce the bone plate set price. Also, custom plates may be assembled to meet specific patient needs, on a case-by-case basis. A great variety of modular bone plate members can be provided and the members can be combined in various manners. For example, the modular bone plate can be used with bone anchors with spherical heads that allow for an angled configuration of the bone anchor relative to the bone plate, with set screws, with plugs to close the holes etc. or with combinations thereof. This opens a great field of clinical applications. Because of this easy and secure assembly and the resulting strong construct, the surgeon can select different modular pieces and assemble a custom bone plate directly in the operating room, used for a specific application. 
         [0010]    Modifications of the design of the modular bone plate member allow the surgeon to connect the members to form an angled configuration with a variable angle that can be selected by the surgeon. Further modifications allow for modular bone plate members of different thicknesses to be combined to form bone plate constructs of variable thickness.” 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Further features and advantages will become apparent from the description of embodiments and means of the accompanying drawings. 
           [0012]    In the drawings: 
           [0013]      FIG. 1 : shows a schematic exploded cross-sectional view of a first embodiment of the modular bone plate with a bone anchor and a cap to secure the bone anchor. 
           [0014]      FIG. 2   a ): shows a perspective exploded view of the modular bone plate according to the first embodiment. 
           [0015]      FIG. 2   b ): shows a perspective view from the bottom of the first plate member of the modular bone plate of  FIG. 1 . 
           [0016]      FIG. 3 : shows a perspective exploded view of the modular bone plate according to the first embodiment wherein the bone plate members have been connected. 
           [0017]      FIG. 4 : shows a cross-sectional view of the modular bone plate according to the first embodiment wherein the bone plate members have been connected and the bone anchor and the cap have been inserted. 
           [0018]      FIG. 5 : shows an enlarged cross-sectional view of the modular bone plate according to the first embodiment with an inserted plug to close the hole. 
           [0019]      FIG. 6 : shows a perspective view from the top of a connector member of the modular bone plate according to the first embodiment. 
           [0020]      FIG. 7 : shows a perspective view from the bottom of the connector member according to  FIG. 6 . 
           [0021]      FIG. 8 : shows a schematic cross-sectional view of the connector member according to  FIG. 6 , wherein the cross-section is taken along line A-A in  FIG. 6 . 
           [0022]      FIG. 9 : shows a perspective view from the top of a second member of the modular bone plate according to the first embodiment. 
           [0023]      FIG. 10 : shows a perspective view from the top of a third member of the modular bone plate according to the first embodiment. 
           [0024]      FIG. 11 : shows a perspective exploded view of the modular bone plate according a modification of the first embodiment. 
           [0025]      FIG. 12 : shows a schematic cross-sectional view of the assembled modular bone plate according to  FIG. 11 . 
           [0026]      FIG. 13 : shows a perspective partially exploded view of a further modification of the modular bone plate according to the first embodiment. 
           [0027]      FIG. 14 : shows a schematic cross-sectional view of the assembled modular bone plate according to  FIG. 13 . 
           [0028]      FIG. 15 : shows an exploded perspective view of a further modification of the modular bone plate according to the first embodiment. 
           [0029]      FIG. 16 : shows a schematic cross-sectional view of the modular bone plate of  FIG. 15  in an assembled state. 
           [0030]      FIG. 17 : shows an exploded perspective view of a further modification of the modular bone plate according to the first embodiment. 
           [0031]      FIG. 18 : shows a perspective view from the top of the modular bone plate of  FIG. 17  in an assembled state. 
           [0032]      FIG. 19   a ) to  c ): shows a top view of a modular bone plate according to a second embodiment in different angular positions of the bone plate members relative to each other. 
           [0033]      FIG. 20   a ) to  e ): shows a perspective view of the modular bone plate according to a modification of the second embodiment in different angular relationships of the bone plate members. 
           [0034]      FIG. 21 : shows a third embodiment of the modular bone plate in side view. 
           [0035]      FIG. 22 : shows a perspective view from the top of a member of the bone plate according to the third embodiment. 
           [0036]      FIG. 23 : shows a further modification of the modular bone plate according to the third embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0037]    As shown in  FIGS. 1 to 4 , the modular bone plate according to the first embodiment includes at least a first member  1  and a second member  2  that are to be connected to each other. The first member is shaped in the form of an elongated plate and comprises a top surface  1   a  and a bottom surface  1   b  that are substantially parallel to each other and define the height of the first member  1 . The first member  1  further has a first free end  1   c  and a second free end  1   d  opposite to the first free end  1   c . Furthermore, the first member  1  comprises a connection portion  10  that serves for connecting the first member  1  to the second member  2 . The connection portion  10  extends from the second free end  1   d  to a distance therefrom in a longitudinal direction of the first member  1 . It comprises a hole  11  that is a through-hole as can be seen in particular in  FIGS. 2   a ) and  2   b ). The edge of the hole  11  that extends to the second free end  1   d  is substantially semi circular and comprises a projection  12  that forms the free end  1   d . The projection  12  is located at a distance, in particular a small distance, from the bottom surface  1   b  at substantially the middle of the height between the top surface  1   a  and the bottom surface  1   b . Further, the connection portion  10  comprises a recess by means of which an upper portion adjacent the top surface  1   a  of the first member is cut out. The recess extends into the first member to a distance from the edge of the hole  11  so as to form a groove  13 . The groove  13  has a distance from the top surface  1   a  that corresponds substantially to the distance of the projection  12  from the bottom surface  1   b . The size and the shape of the grooves correspond to the size and shape of the projection  12 . Hence, the groove  13  is semi-circular. At both free ends of the groove  13  a substantially rectangular recess is provided, as can be seen in particular in  FIGS. 2   a  and  2   b.    
         [0038]    The hole  11  comprises a section  11   a  that is shaped as a segment of a sphere with the smaller diameter oriented towards the bottom surface  1   b . This hollow spherically-shaped portion  11   a  serves as a seat for a spherically-shaped head  31  of a bone anchor  30 . 
         [0039]    The first member  1  comprises a further hole  15  extending from the top surface  1   a  to the bottom surface  1   b . The hole  15  has a first portion  15   a  that is at least partially threaded and is configured to receive a locking cap  40  to be placed onto a spherical head of another bone anchor. The hole  15  further comprises a spherically-shaped portion  15   b  for receiving the spherical head of the bone anchor. 
         [0040]    The second member  2  is also formed as an elongated plate and comprises a top surface  2   a  and a bottom surface  2   b.  The distance between the top surface  2   a  and the bottom surface  2   b  defines the height of the member  2  that is identical to the height of the plate member  1 . The second member  2  has a first free end (not shown in  FIG. 1 ) and an opposite second free end  2   d.    
         [0041]    Similar to the first member  1 , the second member  2  has a connection portion  20  that is to be connected to the connection portion  10  of the first member  1 . The connection portion  20  comprises a hole  21 . The edge of the hole  21  extending to the second free end  2   d  comprises a projection  22  that is semi-circular and sized and arranged so that it fits into the groove  13  of the first connection portion  10 . Further, the second member  2  comprises a recess that cuts out a portion from the bottom surface  1   b  up to substantially the middle of the height of the member  2  and extends to the edge of the hole in a direction to the first end  2   c  so as to form a groove  23 . The groove  23  is sized and arranged to receive the projection  12  of the first member  1 . The hole  21  is at least partially threaded and configured to receive the cap  40  that secures the head of the bone anchor  30 . 
         [0042]    The second member  2  comprises at least a second hole  25  with an at least partially threaded portion  25   a  adjacent the top surface  2   a  and a spherically-shaped portion  25   b  in the lower part to receive a spherical head of another bone anchor. 
         [0043]    In one embodiment, the modular bone plate includes a third piece, such as a cap or screw, for example, to connect and/or hold (compress and/or lock) the two members (the first member  1  and the second member  2 ) together. The third piece functions to maintain the assembly of the plate, after it is placed on the bone. 
         [0044]    The assembly of the modular bone plate will now be described with reference to  FIGS. 3 and 4 . To connect the members  1  and  2  to each other, the members are oriented with their second free ends  1   d ,  2   d  facing towards each other as shown in  FIG. 1 . Then, the projection  22  of the second member is inserted into the groove  13  of the first member. Because of the substantially symmetrical design, the projection  12  of the first member is simultaneously introduced into the groove  23  of the second member  2 . When the projections are fully introduced into the grooves, they abut against the inner wall of the grooves and the holes  11  and  21  overlap. The bottom surface  1   b  of the first member and the bottom surface  2   b  of the second member are substantially flush as can be seen in particular in  FIG. 4 . Due to the recess resulting from groove  13  of the first member, the side faces of the plate members are substantially flush as shown in  FIG. 3 . It is possible to dimension the groove  13  of the first member substantially semi-circular so that the side faces of the plate members are substantially flush as shown in  FIG. 3 . 
         [0045]    The dimensions of the connection portions are such that once connected, the projections fit tightly into the grooves such that the assembled bone plate can be placed onto the bone without the members falling apart. Once the modular bone plate has been placed onto the bone, the bone anchor  30  can be inserted so that the spherical head  31  is seated in the spherically-shaped portion  15   b  of the hole  11 . The bone anchor  30  may have a coaxial through hole  32  for injection of substances or bone cement and/or for guiding through a guide wire that may be used to place the bone anchor into the bone. The bone anchor  30  may assume different angular positions with respect to the plate because the head  31  is accommodated in the spherically-shaped portion  15   b  in the manner of a ball and socket joint. 
         [0046]    The locking cap  40  has a threaded outer surface  40   a  and a spherically-shaped recess  41  oriented towards the spherical head  31  of the bone anchor  30 . On the opposite side, the cap comprises a plurality of pockets  42  for engagement with a driver. The locking cap  40  is screwed into the at least partially threaded hole  21  to secure the bone anchor in the plate and prevent backing out of the bone anchor. 
         [0047]    The connection between the connection portions provides a substantially uniform load distribution between the two plate members. 
         [0048]    In  FIG. 5  the first member  1  and the second member  2  are assembled and the holes  11 ,  21  are closed by a closure plug  45  that is similar to the locking cap  40  in that it has a threaded section  46  cooperating with the threaded hole  21  and pockets  47  for a driver. In the lower part, the closure plug  45  has a spherically-shaped section  48  that fits into the spherically-shaped portion  15   b  of the hole  11 . By means of this, two members can be connected without using a bone anchor. 
         [0049]      FIGS. 6 to 8  show a further member of the modular bone plate. The member  3  is a connector member that has a top surface  3   a,  a bottom surface  3   b,  a first free end  3   c  and a second free end  3   d.  The connector piece comprises two connection portions  10 ,  20 . The first connection portion  10  is arranged at the first free end  3   c  and the second connection portion  20  is arranged at the second free end  3   d.  The first connection portion  10  is identical to the first connection portion  10  of the first member  1  and the second connection portion  20  is identical to the second connection portion  20  of the second member  2  described above. Therefore, all details of the first and second connection portion  10 ,  20  are indicated with the same reference numerals as for the first member  1  and the second member  2 . The description thereof will not be repeated. 
         [0050]    The connector member  3  serves as an intermediate member that may connect to other members of the type of the first member  1  and the second member  2 . The distance between the first and the second connection portion may vary so that a plurality of connector pieces in the form of the third member  3  can be provided that have different length. 
         [0051]      FIG. 9  shows a modified third member  3 ′ that differs from the third member  3  shown in  FIGS. 6 to 8  in that a further hole  27  is provided between the first connection portion  10  and the second connection portion  20 . The hole  27  has an at least partially threaded portion  27   a  adjacent the top surface  3   a  and a spherically-shaped portion  27   b  for accommodating the spherical head  31  of a bone anchor that is similar to the bone anchor  30 . It may be envisaged that several additional holes can be provided between the first connection portion  10  and the second connection portion  20 . 
         [0052]      FIG. 10  shows an end member  2 ′, similar to the first member  1 . Preferably, the end member has a rounded free end  2   c.    
         [0053]      FIGS. 11 and 12  show a further modification of the modular bone plate according to the first embodiment. The plate members  1 ′,  2 ″ differ from the plate members  1  and  2 ′ described before in the connection portion  10 ′,  20 ′, respectively. The connection portions  10 ′,  20 ′ each have a threaded hole of the same size. When the plate members  1 ′,  2 ″ are connected to each other a set screw  50  can be screwed-in to connect the plate members. All details that are identical to that of the previous embodiments are indicated with the same reference numerals and the description thereof is not repeated. 
         [0054]      FIGS. 13 and 14  show a further modification of the modular bone plate shown in  FIGS. 11 and 12 . The plate members  1 ″ and  2 ′″ comprise connection portions  10 ″ and  20 ″″. The holes  11 ″ and  21 ″ are threadless and comprise recesses  11   c ,  21   c  for accommodating a flange  52   a  of nut  52  and a flange  53   a  of a screw  53 , respectively. The nut  52  and the screw  53  cooperate to fix the connection as shown in  FIG. 14 . 
         [0055]      FIGS. 15 and 16  show a further modification of the plate members and the connection thereof. The plate member  1 ′ is substantially identical to the first plate member  1 ′ of  FIGS. 11 and 12 . The plate member  2 ″′ corresponds substantially to the plate member  2 ″′ of  FIGS. 13 and 14 . Hence, a screw  54  with a flange  54   a  can be used to connect the plate members together as shown in  FIG. 16 . 
         [0056]    A further modification of the first embodiment is shown in  FIGS. 17 and 18 . The first plate member  100  has a first connection portion  101  and the second plate member  200  has a second connection portion  201 . The first connection portion  101  and the second connection portion  201  have a greater width than in the previous embodiments. The width may be greater than the remainder of the first member  100  and the second member  200 . However, dependent on the application, the width may also be the same over the length of the plate member. On both sides of the projection  12  in the width direction, there is a groove  103  that extends substantially perpendicular to the length direction of the plate member  100 . The second plate member  200  has a corresponding projection  203  extending perpendicular to the length direction of the plate member  200  that cooperates with the groove  103 . Hence, the groove  13  is enlarged by the groove  103  and the projection  23  is enlarged by the projection  203 . As shown in  FIG. 18  this provides larger contact area of the two plate members  100 ,  200  and simultaneously a greater width of the bone plate. This provides a strengthened connection. 
         [0057]      FIG. 19  shows a still further embodiment of the modular bone plate. The first plate member  1000  and the second plate member  2000  can assume an angled position with respect to each other as shown in  FIGS. 19   a ) and  19   c ). To achieve this, first plate member  1000  has a recess  1114  at both ends of the groove  13  so that, when the second plate member  2000  is inserted with its projection  22  into the groove  13 , there is a gap between the end of the groove  13  and the second plate member  2000  as can be seen in particular in  FIG. 19   b ). This allows for pivoting of the second plate member  2000  with respect to the first plate member  1000  around the axes of the holes  11 ,  21  to a certain angle that may be up to around 10° or 15° (soft angle). 
         [0058]    In a still further embodiment shown in  FIGS. 20   a ) to  20   e ) the groove  13  in the first plate member  1000  is provided at a rotated position with respect to the axes of the holes  11 ,  21 . Positions between around  15 ° , shown in  FIGS. 20   b ) and 90° in  FIG. 20   e ) are possible (hard angle). Because the groove is part of the first connection member  1000  the angle is fixed and can not be changed as in the embodiment of  FIG. 19 . Those having ordinary skill in the art will appreciate that a combination of hard and soft angles may be utilized, according to the above. 
         [0059]    In a further embodiment shown in  FIGS. 21 to 23  a modular bone plate can have different thicknesses along the length of the modular bone plate. To achieve this, a connector piece  300  as shown in  FIG. 22  is provided that has a first portion  300   a  that comprises the first connection portion  10  and a second portion  300   b  that comprises the second connection portion  20 . The bottom surface of portions  300   a  and  300   b  is on the same level. However, the thickness of the portion  300   a  is greater than the thickness of the portion  300   b.  Hence, the connector piece can be used to connect plate members having different thicknesses.  FIG. 21  shows a cascaded configuration wherein the thickness is increasing from one end to the other end of the modular bone plate in steps and  FIG. 23  shows an application wherein the thickness is greatest in the center part of the bone plate. 
         [0060]    Referring now to  FIGS. 24-26 , schematic diagrams of a further embodiment are shown in which longer flanges or tongues  61  and  62  are provided. The longer flanges may enable more stable connections between members  1  and  2 , due to better distribution of forces, for example. In  FIG. 26 , a locking cap  63  is shown for fastening together members  1  and  2 . The embodiment described with respect to  FIGS. 24-26  may otherwise function similarly to earlier-described embodiments. 
         [0061]    The members of the modular bone plate can be made of any bio-compatible material. Preferably, the members are made of titanium, stainless steel, bio-compatible alloys or bio-compatible plastic materials, such as, for example PEEK (polyetheretherketone). The members can be made all of the same material or can be made of different materials so that the modular bone plate has different materials in one portion thereof compared to another portion. 
         [0062]    It should be clear from the above that plate members can be designed in many configurations and are not limited to the specific embodiments shown above. For example, plate members can have less or more holes as shown. The contour of the plate members may vary. The holes may be threaded and provided with spherically-shaped sections for an angled insertion of the bone anchor or may have only threads for straight and fixed angle insertion of the bone anchor. The holes may even have an axis that is not perpendicular to the top and the bottom surface but includes an angle with the top and the bottom surface. The features of all the embodiments described above can be combined among each other to provide a specific plate member needed for a specific application. Therefore, the necessary inventory can be reduced. 
         [0063]    By means of the modularity and the simplicity of handling while ensuring sufficient strength, the field of applications of the modular bone plate is enlarged. Plate members can be produced in all sizes so that the modular bone plate can be used in pediatric orthopedics, cervical spine surgery, hand surgery, long bone treatment and many other applications.