Abstract:
A biocompatible and pliable surgical implant for use in repair and rigid fixation of bone fractures and to compensate for a volume loss is disclosed. The implant includes a biocompatible base member and a volume member having a predetermined volume affixed to the metallic base member. The base is adapted to be secured proximate the fractured bone area.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application takes priority from U.S. Provisional Patent Application Ser. No. 60/629,141, filed on Nov. 18, 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This invention relates to implants and more particularly to an implant device for repairing a fractured bone structure and providing a compensation for a loss of volume.  
         [0004]     2. Background  
         [0005]     Bone fractures in humans and animals may present fracture-related complications. Among such complications is the situation in which bone fragments resulting from a fracture move apart or are crushed, leaving a fracture unable to heal properly without utilizing permanent implants. Often an implant becomes necessary because otherwise the affected bone areas may not align or join properly. Fractures of human facial bones frequently present such characteristics and can be particularly acute at the eye orbit. The eye&#39;s internal bone structure is relatively thin and complex in shape and thus in many situations requires surgical procedures to (a) stabilize the fractured internal orbit bone and (b) insert an implant to compensate for a loss of volume, particularly between the orbit floor and the eyeball. Other bone areas, such as portions of the skull including cheeks and forehead may also require similar surgical procedures.  
         [0006]     In one type of a surgical procedure of the eye orbit, a metallic biocompatible and pliable plate that is trimmed to an appropriate size and shape is placed at the orbit floor and then secured to the front skull bone by screws. Such a procedure is utilized when a portion of the eye orbit is fractured. In this manner, the plate itself rests on the orbit floor and provides a relatively firm or stiff base. If compensation for a loss of volume is necessary, a porous synthetic implant of appropriate thickness and shape is implanted to compensate for such a volume loss. Although the porous implants provide adequate volume, they can migrate out of the implanted locations, thereby losing their effectiveness. Such implants exhibit an increased likelihood to migrate if there is insufficient stable bone around the porous implant or if the bone is unstable. In such cases, the implant may migrate anteriorly or down into the sinus, creating a need for further surgery to correct for the implant migration. In addition, a shift or migration of the porous material from its implanted location can cause the eyeball to sag or shift, which may also require a subsequent surgical procedure and/or a new implant to repair such a condition.  
         [0007]     It is thus desirable to have a biocompatible implant that will (i) provide a necessary support to the fractured or deformed bone structure, (ii) provide a volume to compensate for any diminished volume, such as due to tissue loss, and (iii) not have a tendency to shift after it has been implanted.  
         [0008]     The present invention addresses some of the above-noted problems with currently available implants and provides a implant that provides a structural support for a fractured bone structure and compensation for the loss of volume and methods of making and using such an implant.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention provides an implant that includes a base plate or a base member that provides structural support to a fractured bone area and a volume member affixed to the base plate to provide compensation for a loss of volume. The base plate may be made from any biocompatible material that will provide the desired structural support including a metallic material such as titanium. The shape, size and thickness of the base plate is chosen to provide for the desired internal fixation of fractures, as a material for stabilization of the bone and as a bone graft support material. The plate may include perforations and may be coated with biocompatible material to inhibit in-growth of tissue into the perforation. The volume member may be a porous member made from any suitable material, including a substantially non-metallic material, such as polyurethane.  
         [0010]     The base member may be relatively thin compared to the volume member. The volume member may be affixed to the base member by any suitable manner, including affixing or bonding these members with a suitable adhesive bonding agent or by fusing them together. The implant is placed on the fractured bone area and the base member is secured to an adjacent bone structure in a suitable manner such as with one or more bone screws or any other appropriate attaching device. The base member of the implant will tend to remain in its implanted place where it has been secured and the volume member remains in its implanted location because it is affixed to the base member.  
         [0011]     Examples of the more important features of the invention have been summarized (albeit rather broadly) in order that the detailed description thereof that follows may be better understood and in order that the contributions they represent to the art may be appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject of the claims appended hereto.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     For detailed understanding of the present invention, reference should be made to the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawing wherein like elements have been given like numerals and wherein:  
         [0013]      FIG. 1  is a perspective view of an exemplary human skull showing a fracture of the right eye orbit floor and a fracture in the skull that may require an implant to provide structural support for the fracture areas and compensation for a loss of volume;  
         [0014]      FIG. 2  is a cross-sectional view of an exemplary implant according to one embodiment of the present invention;  
         [0015]      FIG. 3  is a top view of the implant of  FIG. 2 ;  
         [0016]      FIG. 4  shows a top view of an alternative embodiment of an implant according to the present invention;  
         [0017]      FIG. 5  is a top view of an exemplary embodiment of the base plate of the implant of  FIG. 2 ; and  
         [0018]      FIG. 6  is a perspective view of the human skull shown in  FIG. 2  with an implant made according an embodiment of the present invention placed on the orbit floor and attached to the facial bone.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]      FIG. 1  is a perspective view of a human skull  10  showing the right eye orbit  20  with the orbit floor  30 , medial wall  32 , lateral wall  34 , posterior wall  36 , a facial bone structure  38  and the forehead  39 . A variety of bone fractures of the eye orbit  20  can occur due to accidents or congenital defects. Such fractures may occur on one or more areas of the orbit floor  30 . Bone area  40  on the orbit floor is intended to show only an example of a bone fracture of the orbit floor  30 , and represents any fracture type that may require a surgical implant to provide both the structural support to the orbit floor  30  and a certain amount of volume over such a structural support to compensate for a loss of volume for the eye or globe. In reality, many different types of fractures occur in the eye or other areas of the body. Element  41  shows fractures or bone defects in the forehead that may require implants to provide both the bone support and volume compensation. Thus, the apparatus of this invention is intended for use on all such fractures whether on the skull or any other bone area. Also, any volume compensation provided by the implant is desired to remain in the implanted location.  
         [0020]      FIG. 2  shows a cross-sectional view of an exemplary implant  50  according to one embodiment of the present invention. The implant  50  includes a base member (plate, strip or panel)  52 . The plate  52  may include any number of perforations  54 . The plate  52  is usually relatively thin (typically about one mm) and is made from a biocompatible material (i.e., an allopathic material) suitable for use in humans or animals. The plate  52  may be made from titanium or any other suitable biocompatible material. Titanium is an example of widely accepted biocompatible material for such applications. A plate  52  made from titanium, for example, or any other suitable relatively stiff material, can support itself when placed on a fractured area, such as a fractured orbital floor. Platinum is another suitable material and is useful because it has low density and low elastic modulus (stiffness) compared to materials such as stainless steel or cobalt chromium. Titanium plates also are pliable and corrosion resistant. However, for the purpose of this invention any material that will provide the desired or adequate support for the fractured bone portion may be used. Materials such as Teflon, supramid, tantalum, vitallium, polyethylene etc., if suitable, may also be used. Hybrid materials, including metallic and nonmetallic materials, may also be used. A pliable material is desirable because it can be trimmed to a desired shape and size with an instrument such as scissors prior to implanting the implant into the body. The implant also may be made in various anticipated sizes and shapes. The plate  52  may incorporate one or more provisions for securing it to a bone structure such as one or more extensions or fingers  56 , having a suitable through-opening or hole  58  for inserting a securing member, such as a bone screw, therethrough. The extension  56  may also be secured to the bone in any other suitable manner.  
         [0021]     The plate  52 , when placed on the orbit floor  30  and affixed to a bone structure, such as with surgical screws, rests on the orbit floor  30  to provide structural support to the orbit floor. The implant  50  also includes a second member  64  (also referred herein as a volume member) that is attached to a side  65  (usually a top side) of the plate  52 . The volume member  64  is attached to the plate  52  in a manner so that the volume member  64  will tend to remain (or will remain substantially) in place (i.e., not shift) relative to the base plate  52  after the implant has been implanted. The combination member also is referred herein as a hybrid implant or device.  
         [0022]     The volume member  64  may be attached to the plate  52  by any suitable manner including, but not limited to, by an adhesive  60  or any bonding agent or material or by fusing the volume member on to the plate  52 . In another aspect the volume member  64  and the plate  52  may be bonded or attached to each other by a heating mechanism or by an electrochemical reaction. The bonding material may also be of a type that will dissolve over a time period after implantation of the device in the body. As the bonding material dissolves, this allows the body&#39;s natural healing properties or mechanisms to ingrow or vaginate and keep the volume member substantially at its implanted position. Examples of such bonding agents include products sold under the trade names “cyanocrylate” glue or “dermabond”.  
         [0023]     The volume member  64  may be a porous material having any desired shape and size. In the embodiment shown in  FIG. 2 , the volume member  64  has a substantially flat bottom surface  63  and a contoured top surface  68  that has sections  64  and  66  of different thicknesses. The volume member&#39;s contour and the shape depend upon the amount and dimensions of the volume to be compensated. Typically, the volume member  64  is thicker than the plate  52 . The volume member may be a porous member made from a non-metallic biocompatible material such as a polyurethane material. “Medpor,” for example, is such a polyurethane material that is commonly used for compensation of volume in surgical implants. The volume material is usually not compressible by the pressure exerted thereon after the implant. The implant  50 , thus, is a hybrid implant that includes a relatively stiff member, usually a metallic member, that provides structural support to the fractured bone and a volume member  64  that provides for the compensation for loss of volume.  
         [0024]      FIG. 3  shows a top or plan view of a hybrid implant that has a base plate  52 ′ that includes attachment extensions  56  having bone screw holes  58 . The volume member  64 ′ is suitably attached on a surface or side of the plate  52 , by man.  
         [0025]      FIG. 6  shows another embodiment  55   a  of a hybrid implant of the present invention. The implant  55   a  includes a base plate  52   a  suitable for a small longitudinal fracture having holes  54   a  for securing it to the bone and a volume member  64   a  suitably secured to the base plate. The plate  52   a  has no extensions and may or may not have any perforations therein.  
         [0026]      FIG. 5  shows an exemplary embodiment of a base plate  70  that may be used in the present invention. The base plate  70  includes a main section or body that has cuts or openings  74  on each side, opening  76  on the rear side of the plate  70  and opening  78  on the front side. These openings provide flexibility to the plate  70  and allow relatively easy shaping of the plate to match the orbit base or any other fractured bone area. The plate  70  also includes one or more extensions or fingers  80  here shown as an example (on the front side of the plate  70 ), each such finger having an opening  82  to accommodate a bone screw therethrough. It should be noted that bone screw is one convenient manner to secure the plate to the bone. Any other attachment device or method may be used to secure the plate  52  ( FIG. 6 ) to the bone structure for the purpose of this invention. The plate  52  also may include perforations  72  that permit communication between the bone structure and surrounding tissue mass. As noted above, the plate  70  may be made from pure titanium, which has been determined to be suitable as an implant material or any other suitable biocompatible material. The plate  70  also may be coated with a suitable biocompatible to inhibit the in-growth of tissue in the perforations.  
         [0027]      FIG. 4  shows the implant  50  of  FIG. 2  placed or implanted in the right orbit of a human skull. A hybrid implant that matches the need for a particular surgery is selected. The selected implant is then shaped, if necessary, and placed on the orbit floor  30  ( FIG. 1 ) or other fractured bone as the case may be. The extensions  50  are then secured to the facial bone  38  ( FIG. 1 ) by bone screws  90  ( FIG. 6 ). Once the plate  52  is secured or affixed to the facial bone  38 , the base plate  52  remains in its implanted position. Further, since the volume member  64  ( FIG. 2 ) is affixed on to the plate  52 , it will also remain in its initial location without shifting relative to the plate  52 . The base plate  52 , thus, provides the desired structural support to the fractured bone area and remains in its implanted location because it is secured to the bone structure, and the volume member  64  provides for the loss of volume and remains in its implanted location because it is affixed to the base plate  52 .  
         [0028]     In general, the hybrid implant may be made in any number of shapes and sizes during manufacturing. Both the volume member and the base plate element may be modified after manufacture to conform to shape and size for individual situations. The volume member of a desired size and shape is affixed to a compliant base plate. The base plate may include one or more provisions for affixing it to a bone structure.  
         [0029]     The foregoing description is generally directed to embodiments relating to implants for eye orbit. For the purpose of illustration and explanation the implant of the present invention, however, may be used for any surgical procedure in humans or animals. The base plate may also be of any thickness compared to the volume member. It will also be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set for the above are possible without departing from the scope and the spirit of the invention. It is intended that the following claims be interpreted to embrace all such modifications and changes.