Abstract:
A bone loss plate for the rigid fixation of a bone having a bone gap where portions of the bone are absent, the plate includes an elongated fixation plate having a first plate side, a second plate side, a proximal portion, a distal portion, and a middle portion and a tubularly-shaped containment cage connected to the second plate side of the elongated fixation plate, the tubular containment cage having a length shorter than the elongated fixation plate.

Description:
[0001]    This application claims the benefit of U.S. Provisional Patent Application No. 60/879,896, filed Jan. 11, 2007. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to medical implants. Particularly, the present invention relates to fracture plates and cages. More particularly, the present invention relates to a bone loss plate for the rigid fixation of long bone fracture where there is significant bone loss at the fracture site or bone loss gaps caused by pathological processes. 
         [0004]    2. Description of the Prior Art 
         [0005]    Fracture plates and cages have been in use for years. Typically, fracture plates and cages are comprised of separate fracture plates and metallic mesh cages. Plates are used to immobilize bone fractures and to maintain alignment during the healing process. Cages have been used to make up the space in areas of bone loss due to fracture or other pathologic processes. 
         [0006]    The main problem with conventional fracture plates is that plates cannot close gaps between the fractured ends of severely damaged bones. Bone does not heal if significant gaps exist between fracture fragments of broken or otherwise damaged opposing bone ends. If there is bone loss at the fracture site the use of a conventional plating system requires the fracture ends to be pulled together shortening the overall length of the original bone. 
         [0007]    Alternatively, mesh cylindrical cages filled with osteogenic material may be inserted into the gap prior to assembling the plate system to the fractured bone. A drawback of conventional cages used to fill gaps in damaged bone is that the cages may migrate out of position. Additionally, conventional cages do not provide immobilization of the fractured bone nor can they maintain alignment of the fractured bone. 
         [0008]    While these devices may be suitable in some circumstances, they are not as suitable for the rigid fixation of long bone fracture where there is significant bone loss at the fracture site or bone loss gap caused by pathological processes. 
         [0009]    U.S. Pat. No. 4,938,768 discloses a bone gap bridging and fusing device. The bone gap bridging device includes first and second pin members adapted to be placed in axial openings formed in the opposed remaining bone portions. Each pin member includes a head and the heads of the pin members interengage one another to prevent relative rotation between the pin members. A collar telescopes over the interengaged heads to lock the pin members axially relative to one another. 
         [0010]    This device suffers the disadvantage that tapered openings in axial alignment must be formed in the ends of the bone portions in order to receive the pin members of the device. Additionally, the collar and the pin members must have mating threads as well as set screws to fix the collar in position relative to the pin members, which adds to the cost of the device. 
         [0011]    Therefore, what is needed is a device and method to rigidly fix a long bone fracture where there is significant bone loss at the fracture site or caused by pathological processes. What is also needed is a device and method that also fills the gap produced by the bone loss so that shortening does not occur. What is further needed is a device and method that provides immobilization and maintenance of alignment of a bone fracture while eliminating or minimizing the shortening of the bone caused by bone loss. 
       SUMMARY OF THE INVENTION 
       [0012]    It is an object of the present invention to provide a device and method that rigidly fixes a long bone fracture where there is significant bone loss at the fracture site. It is another object of the present invention to provide a device and method that fills the gap produced by the bone loss so that shortening does not occur. It is a further object of the present invention to provide a device and method that provides immobilization and maintains alignment of a bone fracture while eliminating or minimizing the shortening of the bone caused by bone loss. It is still another object of the present invention to provide a device and method that combines cages designed to fit into the areas of bone loss due to severe trauma with a stability providing plate. It is yet another object of the present invention to provide a device and method that eliminates the possibility that the cage will migrate out of optimum position. It is another object of the present invention to provide a weight-bearing surface upon which the fracture ends can be seated during the healing process. It is a further object of the present invention to provide a device that has a known volume. It is an object of the present invention to provide a device that physically contains the osteogenic material placed inside it. It is still another object of the present invention to provide a device that that can fill gaps in long bones produced by pathological processes such as infections, trauma and tumors. It is yet another object of the present invention to provide a device that immobilizes the spine while filling the defects in vertebral bodies or disc spaces. 
         [0013]    The present invention achieves these and other objectives by providing a bone loss plate having a fixation plate and a tubularly-shaped containment cage connected to the fixation plate. The fixation plate has a first plate side, a second plate side, is preferably rectangularly shaped, and has a proximal portion, a distal portion and a middle portion. The proximal and distal portions have a plurality of openings through which fasteners are positioned to fixedly attach the plate to the respective ends of the fractured bone. 
         [0014]    The tubularly-shaped containment cage is preferably an elliptically-shaped metallic mesh basket that has a diameter approximately equal to the diameter of the fractured bone ends. The plate side of the tubularly-shaped cage is connected to the middle portion of the plate and may optionally be integrally formed into the middle portion of the plate. The tubularly-shaped cage may optionally include cage braces and, preferably, top and bottom cage braces. In the elliptically-shaped embodiment, the top and bottom cage braces are symmetrically placed along a chord line at each end. 
         [0015]    Preferably, the tubular containment cage has a shape defined by the shape of the bone to which the bone loss plate is to be attached. Thus, the tubular containment cage is preferably customized for the installed location. It is also preferable that the ends of the tubular containment cage have a diameter about the same as the diameter of the ends of the bones to be joined. The tubular containment cage may optionally be configured to be expandable. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective rear view of one embodiment of the present invention showing the bone loss plate. 
           [0017]      FIG. 2  is a perspective front view of the embodiment in  FIG. 1  showing the tubularly-shaped containment cage. 
           [0018]      FIG. 3  is a perspective side view of the embodiment in  FIG. 1  showing the mesh structure of the tubularly-shaped containment cage. 
           [0019]      FIG. 4  is a perspective top view of the embodiment in  FIG. 1  showing the inside of the tubularly-shaped containment cage. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]    The preferred embodiment of the present invention is illustrated in  FIGS. 1-4 .  FIG. 1  shows a perspective back view of the bone loss plate  10  of the present invention. Bone loss plate  10  has a fixation plate  20  showing a second plate side  21  and a tubularly-shaped containment cage  40 . Fixation plate  20  has a proximal portion  22 , a distal portion  24  and a middle portion  26 . Proximal portion  22  and distal portion  24  have a plurality of fastener openings  28 . Middle portion optionally includes a cage aperture  30  and provides access to the inside of tubularly-shaped containment cage  40 . 
         [0021]    For example, to treat a tibial fracture in an average adult male, proximal and distal portions  22 ,  24  of plate  20  are typically about 4 mm. thick, about 20 mm. wide and about 40 mm. long. The plurality of fastener openings  28  in proximal and distal portions  22 ,  24  also have four or more holes approximately 4 mm. in diameter through which fasteners such as, for example, screws are used to fixedly attach plate  20  to the respective fractured bone ends. The plurality of fastener openings  28  are aligned adjacent the longitudinal axis of plate  20 . Fasteners other than screws may be used to fixedly attach plate  20  to the bone. In certain clinical situations, it may be advantageous to form plate ends  32  in a curvilinear shape. In other embodiments, optional cage aperture  30  may be incorporated into the middle section  26  of plate  20  so that osteogenic material can be disposed inside tubularly-shaped cage  40  after positioning bone loss plate  10  in the bone fracture area. It should be understood that osteogenic material can also be disposed inside tubularly-shaped cage  40  before positioning bone loss plate  10  in the bone fracture area. 
         [0022]    Turning now to  FIG. 2 , there is illustrated a perspective front view of the present invention. Tubularly-shaped containment cage  40  is preferably an elliptically-shaped metallic mesh structure  42  that has a diameter approximately equal to the diameter of the fractured bone ends. The plate side of the tubularly-shaped containment cage  40  is connected to middle portion  26  of a first plate side  23  of plate  20  and may optionally be integrally formed into middle portion  26 . Tubularly-shaped containment cage  40  may optionally include one or more cage braces  50  and, preferably, top and bottom cage braces  50 . In the elliptically-shaped embodiment, the top and bottom cage braces  50  are symmetrically placed along a chord line of tubularly-shaped containment cage  40 . 
         [0023]    Preferably, tubularly-shaped containment cage  40  is an elliptically-shaped, metallic, mesh cage that is integrally connected to middle portion  26  of plate  20 . The mesh structure  42  provides a plurality of cage wall openings  44  and is more clearly shown in  FIG. 3 . The height of containment cage  40  is dictated by the length of bone that it is intended to replace. The shape of containment cage  40  is dictated by the shape of the bone requiring treatment. Thus, the shape and size of tubularly-shaped containment cage  40  is customized accordingly. 
         [0024]    The cross-sectional shape of each end  48 ,  48 ′ of the tubularly-shaped containment cage  40  is preferably an approximate mirror image of the cross-section of the respective ends of the bone that it is supporting. Containment cage  40  preferably has cage braces  50  symmetrically placed along a chord line at each end  48 ,  48 ′ and preferably made of the same material as containment cage  40 . An optional feature of containment cage  40  is that it may be detachable from fixation plate  20 , a feature that would be advantageous in certain instances. In other embodiments, it is advantageous to make containment cage  40  from a material different from that of plate  20 . Containment cage  40  may optionally be expandable along its longitudinal axis. This optional feature provides a single bone loss plate  20  that is usable in situations where the bone gap varies or is adaptable for different sized bone gaps. This optional feature reduces cost by standardization. 
         [0025]    Turning now to  FIG. 4 , there is illustrated a perspective top view of the present invention. As can be seen, tubularly-shaped containment cage  40  has an internal space  52  formed by circumferential cage wall  44 . Cage braces  50  disposed at cage ends  48 ,  48 ′ are more clearly shown. As previously disclosed, an osteogenic material may optionally be disposed in internal space  52  either before or after placement of bone loss plate  10 . The mesh wall structure allows bone growth to penetrate containment cage  40  during the healing process. 
         [0026]    Bone loss plate  10  is used to treat bone pathology where a significant portion of bone is lost. The bone requiring treatment can be envisioned to have two ends, one proximal and one distal, and a gap of unspecified length between the two opposing ends. Tubularly-shaped containment cage  40  of bone loss plate  10 , being approximately concentric with the cross-sectional shape of the bone ends, is placed in the gap in the bone so that the opposing ends of the bone will be in contact and supported by the cage ends  48 ,  48 ′ of containment cage  40  and optional cage braces  50 . Containment cage  40  may be filled with osteogenic material before or after positioning. When containment cage  40  is properly positioned in the gap, fixation plate  20  will lay flat along the length of the respective shafts of the pathologic bone. Fixation plate  20  is then fastened to the bone shafts by screws that are placed through fastener openings  28  in fixation plate  20 . 
         [0027]    Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.