Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of prior filed U.S. Provisional Patent Application, Ser. Nos. 60/806,731 filed 7 Jul. 2006, and 60/806,733 also filed 7 Jul. 2006, which applications are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention is in the field of surgically implanted orthopedic devices, implants and prostheses used in orthopedic surgery. More specifically, the present invention relates to bone plates used to reinforce fractured bones and thus to promote healing. 
     BACKGROUND OF THE INVENTION 
     A compressive screw system, also known as the DCS system, is a bone plate system that has been used in trauma surgery for many years. The procedures for use of this system are well documented by the AO Institute (Davos, Switzerland), an institute having as one of its goals, the promotion of new orthopedic surgical procedures. This system included a bone plate having slots communicating therethrough. A land in which the slot is wider at one end defines a stepped surface adjacent the portion of the slot that extends through the bone plate. The stepped surface is generally cut with a spherical endmill, thus creating a spherical stepped surface. 
     In a still further development, bone plates exist which have individual threaded apertures and non-threaded apertures interspersed along the length of the plate. In this and other designs, the distance between holes has become a standard. Although an improvement over the inserts noted above, the locking positions are pre-defined and only available in limited locations, which also reduce surgical flexibility. In another product variation, expandable, lockable inserts enter into the slots of a standard bone plate. When the bone screw passes through one of these inserts and is torqued down, the insert expands and locks the screw in place. However, this insert is locked in a secondary operation. This is not desirable because this requires more operating room time and adds complexity to the procedure. Further, the inserts must be added in the specific location before the plate is fixed to the bone and cannot be subsequently inserted. This limits the choice of placement during surgery if the need arises. 
     Also, the above insert designs rely on a friction lock via contact between two simple surfaces. Simple surface friction locks are not reliable and come loose more easily than threaded locked holes. The result of such a design is inferior to that of the threaded plate and screw designs discussed below. 
     In U.S. Pat. No. 5,002,544, there is shown an osteosynthetic pressure plate having a cross-section transverse to the longitudinal axis of the plate at least at one point being wider toward the upper surface than toward the lower surface and the plate having recesses in the lower surface so that upon application to a bone there is space between the bone and the plate. The cross-section between the screw holes is reduced, preferably to the extent that the resistance of the plate to bending in this area is less than in the area of the holes. Because of the reduced bend resistance between the holes, the plate can more easily be adapted to conform to the anatomy of the bone. Furthermore, this can be done without deformation of the holes, thus minimizing the resulting loss of fatigue strength and minimizing the misfit of the screw heads. 
     Further, U.S. Pat. No. 5,709,686 describes a bone plate that has recesses or reduced thickness portions on its sides, between threaded apertures. Although the purpose is not specifically described, these recesses appear to function to avoid warping of the threaded portions when the bone plate is bent. However, when such a bone plate is fixed to a bone, these discontinuous recesses are exposed and may potentially come into contact with and potentially aggravate muscle tissue. 
     Still further, U.S. Pat. No. 5,733,287 shows, in  FIG. 4 , a plate that has transverse cuts  13  and a longitudinal cut  14  on the lower surface  7  to reduce contact between the plate and bone. Due to the transverse undercuts  13 , the cross-section between the holes is already significantly reduced and therefore is not further decreased by an additional groove  10  on the upper surface  6  as in the embodiment according to  FIG. 3 . To avoid a cross-section that is too thin, the groove  10  on the upper surface  6  is made discontinuous in short segmental grooves  16  providing a smooth transition into and out of the holes  8 . 
     In yet another solution, PCT application no. WO 01/54601 combines the features of the DCS system discussed above with a locking screw. Such a system is known as the combi-slot. In this design, the stepped surface of the slot is generally ramped or tapered so as to be deeper at one end than at another. This enables the positioning and selective fixing of the bone plate for compressing two bone fragments together with a preload created by wedging action. In this manner, the bones are placed in a position that the surgeon believes would best promote healing. 
     Further, this combi-hole includes two distinct overlapping portions in a single slot. One portion of the slot is suited to receive a standard bone screw, while the other portion of the slot is suited to receive a threaded peg oriented perpendicular to the top surface of the bone plate. Also, the combi-holes are generally oriented with the threaded portions being on the innermost end of the combination and the unthreaded portions oriented toward the ends of the bone plate. This improvement increased the flexibility of choice available to orthopedic surgeons using the device in that it was more likely that a hole would be present at a suitable anchoring point in the bone plate. Nevertheless, there are often trauma situations that are best served by the threaded portion being at the extreme ends of the bone plate and/or at various positions throughout the plate. In addition, sometimes there is no specific center of the facture-in such a situation; use of the combi-hole design is limited. The combi-hole if further limited in that it allows the fixing of a screw in either the slotted portion or the threaded portion, but not both. 
     While patent application no. WO 01/54601 has proven advantageous because screws can be locked to the plate; the presence of an unthreaded slot limits the user&#39;s ability to have multiple orientations for the screw. 
     In a further development, the AO Institute has studied and proposed the use of endpegs which are rigidly fixed in the extreme ends of the bone plate. Such an arrangement has been shown to better resist the flexing of the bone than use of a bone screw alone. Flexing can otherwise loosen the connection between the bone plate and bone in other bone plate systems. 
     U.S. Pat. No. 5,324,290 shows a complex bone plate having slots with countersunk circular recessed cuts at intervals along the slot (a similar arrangement is shown in U.S. Pat. No. 4,696,290). It further shows the bone plate torqued against the bone so as to at least marginally, conform to the shape of the bone (see  FIG. 2 ). Other patents of interest include U.S. Pat. Nos. 3,716,050; 3,659,595; 5,681,311; 5,261,910, and 5,364,399, as well as German Patent application DE4341980A1, all showing combinations of conventional slots and recesses which do not fully accommodate a bone screw having a threaded head. In comparison with the combi-hole design and the friction locking design described above, what is needed is a bone plate that provides greater flexibility of choice to the surgeon. More specifically, what is needed is a bone plate that provides this choice of plate placement while reliably and permanently fixing the bone plate to the bone fragments, in any hole position. 
     What is needed is a bone plate that provides greater flexibility of choice to the surgeon, in a bone plate that has multiple orientations for the locking screw and thus, plate placement, while reliably and permanently fixing the bone plate to the bone fragments, in any hole position. 
     In addition, what is needed is a versatile bone plate having recesses which determine where the bone plate will bend, in order to avoid the threads in any holes to be bent or warped, while maintaining a smooth external surface. 
     Finally, what is needed is a bone plate with holes that create bi-directional compression. 
     SUMMARY OF THE INVENTION 
     The present invention is bone plates of complex form, for use with a bone plate having a main longitudinal axis, a bone-contacting bottom side and a top side with a plurality of bone screw apertures. At least one pair of the bone screw apertures are closely spaced apart and have a center-to-center distance d which corresponds substantially to the sum of the largest radii (r 1 +r 2 ) of the two screw apertures, and further defining an unthreaded circular relief joining the holes, or a transverse slot joining the holes. When applied to a bone, two pairs of adjacent adjoining holes are located so as to lie on opposite sides of an osteotomy site. The configuration of this complex bone plate varies, depending on the physiology of the patient. 
     An object of the invention is to provide a surgeon with the option of placing two bone screws in abutting adjacent positions. Another object of the invention is to provide an orthopaedic surgeon greater flexibility of choice in that a threaded peg or screw providing secure fixing can be positioned at any interval along the bone plate, including at its extreme ends or on its elbow. Another object is to ensure bending along the slot instead of at the threads. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  respectively are top views of a bone plate of the invention incorporating one type of bend relief space, and a close-up view of the first end of the bone plate. 
         FIG. 1C  is a top plan view similar to that of  FIG. 1B , but showing an alternative embodiment incorporating the relief-notch feature of the present invention. 
         FIGS. 2A and 2B  respectively are top views of a bone plate of the invention incorporating an alternative type of bend relief space, and a close-up view of the first end of the bone plate. 
         FIG. 2C  is a top plan view similar to that of  FIG. 2B , but showing an alternative embodiment incorporating the relief-notch feature of the present invention. 
         FIGS. 3A and 3B  are cross-sectional side views of a section of the bone plate of  FIGS. 1A and 2A  taken along line  3 B and illustrating a location for the bend relief space. 
         FIGS. 3C and 3D  are cross-sectional side views of a section of the bone plate of  FIGS. 3B , and illustrate that the bone plate may be bent by an angle A across a bend relief zone and the bending of the plate does not deform the screw apertures, and in  3 D, how it interacts with the surface of a bone fragment. 
         FIG. 4  is a side view of an exemplary assembly of the screws and bone plate of the present invention. 
         FIG. 5  is a schematic illustration of the present bone plate fixed to a bone. 
         FIGS. 6A and 6B  are top-side and bottom-side plan views detailing respective portions of the present bone plate. 
         FIG. 6C  is atop-side perspective view of a portion of the present bone plate with bone screws inserted into two of the complex apertures. 
         FIG. 7  is a top view of a kit of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, the details of preferred embodiments of the present invention are graphically and schematically illustrated. Like elements in the drawings are represented by like numbers, and any similar elements are represented by like numbers with a different lower case letter suffix. 
     As exemplified in  FIGS. 1A and 2A , the present bone plate  10  has a main longitudinal axis  12 , a bone-contacting bottom side  16  (see  FIG. 4 ), a top side  14  and opposite first  20  and second  22  plate ends. A series of screw apertures  24  extending from the top side  14  of the plate  10  through to its bottom side  16  are formed along the plate axis  12 . The screw apertures  24  serve as bone screw guides through which points bone screws  28  are inserted into underlying bone to anchor the bone plate  10  to different parts or fragments of a bone  80  to be reinforced by the bone plate  10  (see  FIG. 5 ). The screw apertures  24  have a screw axis  26  (the general path that a screw takes when inserted through the aperture) which is either perpendicular or angled (see  FIGS. 1B and 2B ) relative to the plane of the bone plate  10  in the vicinity of the screw aperture  24  depending on the need of a particular application or surgical protocol. Additionally, the bone plate  10  of the present invention has one or more bend relief zones  60  separating certain closely spaced apart screw apertures  24 . 
     Additionally, the present bone plate  10  includes angled screw apertures  24   a . Referring now to  FIGS. 1B and 2B , two angled apertures  24   a,  preferably positioned proximate the plate ends  20 ,  22  of the bone plate  10 , have screw axes  26  that are angled from perpendicular of the plane of the bone plate  10  in opposing orientations. The orientation is selectable by one of skill in the field to provide an optimal utility for a variety of operative procedures. In this particular embodiment, the angled holes  24   a  in the plate ends  20 ,  22  are inclined at an angle of approximately forty-five degrees relative to the plane of the topside  14  of the bone plate  10 , which passes through the longitudinal axis  12 . The angled apertures  24   a  are disposed relative to each other to accept and to guide a bone screw  28  at opposing angles in order to securely anchor the bone plate  10  to the bone fragment  80  (see  FIG. 5 ). 
     Referring now to  FIG. 3B  and to  FIG. 6A , the center-to-center distance d of the two screw apertures  24   b  of the duplex-aperture  40  corresponds substantially to the diameter d of one of the screws  28  in the complex aperture  40 . Alternatively, the center-to-center distance d of the two screw apertures  24   b  of the duplex-aperture  40  corresponds substantially at least to the sum of the radii of the of the two screw apertures  24   b,  i.e., r 1 +r 2 &lt;=d. This configuration (when advantageous to a particular operation) enables the heads of the bone screws  28  to be positioned as close together as possible, and even to be touching. 
     It should be noted that screw apertures  24  can be configured to be complementary to bone screws  28  having a number of configurations of screw heads  30  and shanks  32 . For example, as exemplified in  FIGS. 3A and 3B , a bone screw  28  can have a threaded-head  30   a  or an unthreaded-head  30   b . Additionally, a bone screw  28  with a threaded-head  30   a  can have a threaded-shank  32   a  or an unthreaded-shank  32   b  (see  FIG. 7 ). Correspondingly, the screw apertures  24  can have head-seat  34  for receiving a bone screw  28  that is a threaded-seat  34   a  or an unthreaded-seat  34   b  to respectively receive a bone screw  28  having a threaded-head  30   a  or an unthreaded-head  30   b . The bone plate  10  may optionally use a locking bone peg  50 , i.e., a bone screw  28  with a threaded-head  30   a  and unthreaded-shank  32   b  (see  FIG. 7 ). Preferably, the threads cut in the head of the bone pegs  50  are designed so as to lock, with the threaded apertures  34   a  in order to better ensure rigid fixing of a fracture. The locking feature used can be any of the known methods of locking threads by mechanical means. 
     Also, as illustrated in  FIGS. 3C and 3D , the elongated plate  11  of the present invention has one or more bend relief zones  60 . As exemplified in the figures, particular utility of a bend relief zone  60  as a feature of the present bone plate  10  is that it provides a point on the bone plate that allows the elongated plate  11  to be more easily and controllably bent. More particularly, a bend relief zone  60  is disposed between certain. closely spaced apart screw apertures  24 . A bend relief zone  60  so disposed enables the bone plate  10  to be bent by an angle A across the bend relief zone  60  without deforming the screw apertures  24  adjacent the bend relief zone  60 . As shown in the figures, bend relief zones  60  can be provided at different locations on the elongated plate  11 . In the embodiments illustrated, the bend relief zones  60  are arranged perpendicular to the axis  12  of the bone plate, but could also be at an angle across the axis  12 . The present bend relief zone  60  is a part of the bone plate  10  that has sufficient material removed from around the axis  12  of the bone plate  10  to create a relief zone in the material of the bone plate  10  that is more readily bent than the material defining an adjacent screw aperture  24 . The bend relief zones  60  of the present invention allow the precise bending of a bone plate  10  to less than an angle A without distortion of the threaded portion of the head-seat  34  of adjacent screw apertures  24 . It should be noted that because bone plate  10  is intended to be distortable at the bend relief zone  60 , the bend relief zone  60  is never threaded. An advantage of this feature is that a surgeon is able to install two bone screws  28  with threaded-heads  30   a substantially side by side, substantially abutting one another. This would be difficult to accomplish in a plate having threaded-seat screw apertures without a bend relief zone, and is impossible to accomplish in a bone plate with overlapping threaded holes (i.e., their center to center distance being less than d). 
     In the embodiment illustrated in FIG,  4 , a pair of angled screw apertures  24   a  is shown at the first plate end  20  of a bone plate  10  with bone screws  28  installed through them. In another preferred embodiment, a pair of angled screw apertures  24   a  can be disposed at both first and second plate ends  20 ,  22  of a bone plate  10 . In this embodiment, the screw axes  26  of the angled screw apertures  24   a  at the first plate end  20  slant toward the second plate end  22 . This general configuration of the bone screw axes  26   a ,  26   b  forms a triangular truss-like structure with the axis  12  of the elongated plate  11  that is able to resist a wide range of forces which could otherwise tend to loosen an installed bone plate  10 . Consequently, this configuration resists pull-out forces coming from a wider range of directions. Although  FIG. 4  shows the screw axes  26  of the angled screw apertures  24   a  at the first plate end  20  slanted toward the second plate end  22 , they can slant in the opposite direction as shown in  FIGS. 1B and 2B . Additionally, screw apertures  24  proximate the plate ends  20 ,  22  are independent of screw apertures  24  located in the mid-section of the bone plate  10 . 
     The bone plate  10  has at least one duplex screw aperture  40  made up of two apertures  24  adjoined by a relief zone  60 . Multiplex screw apertures (not shown) made up of more than two screw apertures  24  are anticipated, but at least one pair of the of the screw apertures  24  is separated by a bend relief zone. The bend relief zone in the preferred embodiment of  FIGS. 1A and 1B  is an oblong relief  60   a.  In the alternative preferred embodiment of  FIGS. 2A and 2B , the bend relief zone  60  is a slot  60   b  transverse to the axis  12  of the bone plate  10 . 
     Referring now to  FIG. 5 , in another embodiment, the bone plate  10  is particularly suited for femoral osteotomies and/or other corrective osteotomies of the femur. The bone plate  10  has a main longitudinal axis  12 , a bone contacting bottom side  16  and a top side  14  with at least two pairs of screw apertures  24 . The embodiment shown has multiple pairs of duplex apertures  40  and two pairs of angled apertures  24   a.  The closely spaced apart pairs of screw apertures  24  of a complex aperture  40  can act as a compression fitting. When applied to a bone part  80 , each pair of screw apertures  24  of a complex aperture  40  can be disposed to lie on opposite sides  51  of an osteotomy site  44 . 
     A duplex-aperture  40  preferably has wide bevels  41  on a far and near end with respect to the plate axis  12 , and have defined threaded or multifaceted head-seats  34 . The bone plate  10  may optionally use a locking bone peg  50 , i.e., a bone screw  28  with a threaded-head  30   a  and unthreaded-shank  32   b  (see  FIG. 7 ). The threads cut in the head of these pegs  50  are designed so as to lock with the threaded apertures  34   a  in order to better ensure rigid fixing of a fracture. The locking feature used can be any of the known methods of locking threads by mechanical means. 
     A preferred embodiment of the present bone plate  10   a  is illustrated in  FIGS. 1C and 2C  and in  FIGS. 6A to 6C . In this embodiment, the complex apertures  40   a  are similar to the complex apertures described above, but differ in that they have a relief notch  84  disposed in the screw head seat  34  portion of one or both screw apertures  24 . The relief notch  84  provides desirable advantages that are not similarly accomplished in their absence. For example, as shown in  FIG. 6A , a self-locking insert  92  can be disposed in the notch  84  to provide increased friction for setting a threaded head bone screw  30   a  set in a threaded aperture  24   a . As also illustrated in  FIGS. 6A and 6B , it is intended that a screw aperture  24  may have more than one relief notch  84   a . A further example of an advantage of the present notch feature is illustrated in  FIG. 6C , which illustrates that a tensioning wire  88  may be looped around a first bone screw  28   d , passed along the bottom side  16  of the elongated plate  11  and the ends of the wire  88   a  drawn up to the top side  14  of the elongated plate  11  through the recess notch  84   b  in an adjacent second bone screw  28   e . In the embodiment illustrated in  FIG. 6B , the bottom-side  16  of the elongated plate  11  is provided with a clearance channel  94  recessed into the surface of the bottom-side  16  of the plate  11 . The clearance channel  94  communicates with the relief notches  84  to provide a path for the tensioning wire  88  to be easily removed through the relief notch  84   a  after the bone screws  28   d ,  28   e  have been set against the bone plate  10   a.    
     Preferably, the notch feature  84  defines a screw aperture  24  having a threaded screw head seat  34   a  with at least one threaded surface portion  35  and one unthreaded surface portion  36 . In a complex aperture  40   a , the notch feature  84  defines a screw aperture  24  in which the threaded screw head seat  34   a  has at least two threaded surface portions  35  and two unthreaded surface portions  36 , with one of the at least two unthreaded surface portions being the relief zone  60 . 
     Referring now to  FIG. 7 , in another embodiment, an orthopedic bone plate kit  100  includes a compartmented container  102 , preferably having shaped compartment spaces  104  corresponding to the shape of the kit item  106  to be received in the shaped compartment space  104 . Kit items  106  contained in the kit  100  include one or more bone plates  10  having the same or similar elongated plate features  11   a  and  11   b , and a plurality of bone screws  28 . Note that the bone screws  28  may be of a variety of somewhat different configurations practicable with the screw apertures  24  of the present invention. As examples, included in the kit  100  shown are: threaded-head bone screws  30   a , unthreaded-head bone screws  30   a  (both with threaded shanks) and threaded-head pegs  32   b  (i.e., an unthreaded shank), all can be of various lengths. Additionally shown in the kit  100  is a drill guide  110 . The drill guide  110  has a threaded end  112  that can screw into the threaded-seat  34   a  on a screw aperture  24 . The drill guide has a hollow bore  114  that serves as a guide for a drill bit (not shown) for use in drilling a pilot hole in the bone for the bone screw  28  that is to be inserted into the bone through the screw aperture  24 . 
     In another advantage, the invention enables spacing between bone screws  28  that is so close that the surgeon is able to maintain a standard spacing such as that purveyed by the AO Institute (Davos, Switzerland). 
     In another advantage, where a fracture line runs between adjacent screw apertures  24  of a duplex-aperture  40 , a surgeon is able to place a bone screw  28  on opposite sides of the fracture line, thereby better fixing the broken bone together for optimal healing. 
     In another advantage, the bone plate  10  provides greater flexibility of choice by providing multiple complex screw apertures  24  oriented along the longitudinal axis  12  of the bone plate and/or staggered along the axis  12 . 
     In still another advantage, the threaded apertures  34   a  of the elongated plate  11  can be provided with a bone screw axis  26  that is perpendicular or angled relative to the top side  14  of the bone plate  10 . 
     In another advantage, the bone plate  10  includes features that further increase the adaptability of the invention to the particular needs of surgery. The configuration of this complex bone plate  10  may vary, depending on the physiology of the patient. An illustration of the flexibility of application of the plate  80  is its flexible use in osteotomy. 
     While the above description contains many specifics, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of one or another preferred embodiment thereof. Many other variations are possible, which would be obvious to one skilled in the art. Accordingly, the scope of the invention should be determined by the scope of the appended claims and their equivalents, and not just by the embodiments.

Technology Category: 1