Patent Application
20070123881
1. Field of the Invention
The invention pertains to bone plates, and longitudinal plates and center plates that are components of the bone plates, which have off-set sections. The longitudinal plates and center plates which, in part, form the structure of the bone plates have at least one end which contains a protrusion, and when the longitudinal plates and center plates are joined together by connecting rods, the protrusions of adjacent longitudinal plates and center plates are mutually opposed, and the protrusions, in part, stop excess twisting of the bone plate when applied to the broken bone of a patient. The bone plates further comprise one or more observation windows which allow a surgeon to observe the location of a broken bone while moving the pieces of broken bone together.
2. The Related Art
Conventional bone plates have fixed dimensions and multiple holes for accommodating bone screws. Surgeons generally use bone plates to join sections of fractured bone by placing the bone plate atop the fracture, inserting bone screws through the holes in the plate which overlie the healthy part of the bone and securing the bone about the fracture. Bone plates of many sizes are provided for the surgeon, each having a number of holes so that the surgeon can arrange the plate over the fracture and have bone screw holes available above the healthy bone.
DCP dates are also available to stabilize fractured bone. The DCP plates generally have angulated openings, through which screws are “toed” into the bone with the tightening of the toed screws operating to move the bone, slightly, under the DCP plate. DCP plates have been used to move bone pieces on either side of the fracture closer together. However, with a DCP plate, only slight and not easily controllable movements occur. Generally, the underlying bone is pulled into place by the threads of a screw, providing no control over the twisting or turning of the bone, and the bending of the plate. In addition, the bone is pulled at an angle to the attached plates, which can result in a cocked bone, or at an angle to the longitudinal direction of the bone. This angulation, together with the micromotion in the bone, has lead to backing out of the screws after the bone plate is secured to the bone.
Thus, there is a need for bone plates, such as bone plate assemblies which are adjustable, that allow the surgeon to move the broken pieces of bone while inhibiting or preventing the bone from twisting or cocking either during the process of applying the bone plate to the fractured bone or afterwards. Providing the bone plate with one or more windows to allow the surgeon to observe the pieces of fractured bone moving together while the bone plate is adjusted on the bone would also be desired.
The invention pertains to a bone plate which comprises longitudinal plates and, optionally, center plates which have at least one end comprising a protrusion. The longitudinal plates and center plates form a bone plate assembly by the use of connecting rods which allows the surgeon to move the longitudinal plates and center plates and, thus, the bone to which they are attached generally longitudinally prior to fixing the longitudinal length for the bone plate while providing one or more windows for the surgeon to observe the pieces of fractured bone coming together. In the assembled bone plate, the protrusion of one longitudinal plate or center plate is juxtaposed with the protrusion of an adjacent longitudinal plate or center plate thereby establishing, within the window area of the bone plate, an off-set section which provides structural strength to the bone plate and inhibits or prevents twisting and turning of the longitudinal plates and center plates, and the bone plate itself, when the bone plate is being applied to a patient and after application.
The bone plates, i.e. the bone plate assemblies, of the invention comprise longitudinal plates and, optionally, center plates which comprise two ends with at least one end having a protrusion at either the distal side and/or forward side of the longitudinal plate or center plate. The protrusion has an inward wall and an outward wall which are about parallel to each other and the protrusion further comprises an end wall which extends, from the ends of the inward wall and opposite outward wall. The protrusion further comprises an upper surface and a lower surface, which are generally intergral with or part of the upper surface and lower surface of the longitudinal plate and/or the top surface and bottom surface of the center plate. The longitudinal plates further comprise a forward side, a distal side, a top surface and a bottom surface, and may be made a hollow piece or a solid piece. Likewise, the center plate generally comprises a forward longitudinal side, a distal longitudinal side, a first end, a second end, a top surface and a bottom surface, and may be a hollow piece or a solid piece. The longitudinal plates and center plates may further comprise at least one locking means bore defined by a locking means bore wall and at least one bone screw bore defined by a bone screw bore wall. In certain embodiments of the invention the locking means bore is not necessary.
The longitudinal plates and center plates also comprise at least one, such as two or more, rod bores. The rod bores may extend from rod bore openings at an end of the longitudinal plate and center plate and/or from the end wall of the protrusion to a point between the two ends of the longitudinal plate or center plate. The rod bores are defined by rod bore inner walls and rod bore ends. In an embodiment of the invention, however, the rod bores may be continuous, extending from one end to the opposite end, particularly in center plates, in which case the rod bores are defined by at least rod bore walls. The rod bore walls may be any geometrical shape but preferably are continuous walls forming a cylindrical shape to accommodate connecting rods. In an embodiment of the invention, the rod bores comprise threaded rod bore walls or the rod bore walls comprise threaded sections.
The bone plate assembly comprises one or more longitudinal plates and, optionally, one or more center plates and one or more connecting rods. The connecting rods are generally cylindrical elements having a first end and a second end with a continuous outer surface there between. The connecting rods translate within the rod bores to form the bone plate assembly such that the longitudinal plates and center plates are capable of movement by translating with the connecting rods thereby providing the bone plates with adjustability, generally in a longitudinal direction. The connecting rods have an axial dimension that is not completely within the rod bores and, thus, the connecting rods and ends of the longitudinal plates and center plates define one or more windows within the bone plate assembly which allows the surgeon to see the bone coming together under the bone plate when applying the bone plate to a patient. In certain embodiments of the invention, the connecting rods comprise one or more threaded ends, or have slots or comprise one or more retaining pin holes.
The protrusions of adjacent longitudinal plates and/or center plates within the bone plate assembly may be mutually opposed or have surfaces, such as inward walls, juxtaposed with one another thereby establishing an off-set section adjacent to, or preferably within, the window area. This off-set arrangement of the protrusions provides structural strength to the bone plate and inhibits or prevents twisting and turning of the longitudinal plates and center plates, and the bone plate itself, when the bone plate is being applied to a patient and after application.
The second end of each of the first longitudinal plate and second longitudinal plate comprises a recessed edge (shown as 14 with respect to the first longitudinal plate and 15 with respect to the second longitudinal plate) and a protrusion (shown as 16 with respect to the first longitudinal plate and 17 with respect to the second longitudinal plate). Each protrusion comprises an inward wall adjacent to the recessed edge, an end wall adjacent to the inward wall, which may be about perpendicular, or perpendicular to the inward wall, and an outward wall which is adjacent to the end wall, with the outward wall generally parallel to the inward wall. The outward walls of the protrusions are generally extensions of the forward side or distal side, depending on the side of the longitudinal plate that the protrusion is located. As shown in
As shown in the figures, such as
Again referring to
Each longitudinal plate, particularly as shown in
Each longitudinal plate comprises two or more rod bores which are defined by rod bore walls and rod bore ends. For example, as shown in
Each longitudinal plate further comprises a slit, except in the embodiments of the invention wherein the connecting rods are permanently affixed to all rod bores in the longitudinal plate, such as by use of threaded connecting rods and rod bore walls that comprise a threaded section and by use of connecting rods with retaining pin holes used in conjunction with retaining pins, as described in more detail below. As shown in
The slit of each of the first longitudinal plate and/or second longitudinal plate optionally comprises three sections. For example, as shown in
Each longitudinal plate may further comprise one or more locking means bores defined by locking means bore walls and one or more bone screw bores defined by bone screw bore walls. In a preferred embodiment of the invention, the locking means bores are spherical and have a threaded section and the bone screw bores are spherical for angulation of the bone screws and have smooth surfaces, e.g. no threading. In the embodiment of the invention shown in the drawings, each longitudinal plate comprises one locking means bore 59 and two bone screw bores 60a and 60b. As shown in the drawings, the slit of each longitudinal plate extends from the second end through the locking means bores and terminates proximate to one of the bone screw bores preferably the bone screw bore proximate to the locking means bore.
The longitudinal plates are assembled into a bone plate by use of connecting rods which translate within the rod bores. The connecting rods in the bone plates may have different longitudinal lengths. In the embodiment of the invention shown in
The connecting rods may optionally comprise one or more slots. The slots generally extend from a point on the surface of each rod to an opposite point on the surface and are an opening within the rod defined by a slot inner surface. As shown in the drawings, particularly
The bone plate may optionally comprise one or more retaining pins. As shown in
The retaining pins may have threaded sections. For example, the continuous outer surface of the retaining pin may be smooth or may have threads either at the first end or second end of the retaining pin, at both the first end and second end of the retaining pin or along the entire continuous outer surface of the retaining pin. Threading of the retaining pin facilitates intermixing of the longitudinal plates and/or center plates by the surgeon when treating a patient with broken bone(s). Likewise, the retaining pin bores may be threaded either at each end, both ends or along the entire retaining pin bore wall to interact with threaded retaining pins.
In an embodiment of the invention, as shown in
Referring now to
In the embodiment of the invention shown in
When the connecting rods have retaining pin holes or threaded ends, the connecting rods may be effectively secured, i.e. affixed, within the forward rod bore and/or distal rod bore of the first longitudinal plate or second longitudinal plate and then the opposite ends of the connecting rods may be slid into the rod bores of the corresponding plate to which the connecting rods are not effectively secured. Alternatively, one end of one of the connecting rods may be effectively secured within the distal rod bore of the first longitudinal plate and one end of the other connecting rod may be effectively secured within the forward rod bore of the second longitudinal plate, or vice versa, and then the free ends of the connecting rods can be slid in the vacant rod bores of the opposite longitudinal plate, and similar sequencing can be used when the bone plate assembly comprises center plates which are discussed below. For example, a connecting rod may be placed in the distal rod bore of the first longitudinal plate leaving the forward rod bore vacant and a second connecting rod may be placed in the forward rod bore of the second longitudinal plate leaving the distal rod bore vacant, and when the longitudinal plates are brought together, the connecting rod in the distal rod bore of the first longitudinal plate is slid into the distal rod bore of the second longitudinal plate and the connecting rod in the forward rod bore of the second longitudinal plate is slid into the forward rod bore of the first longitudinal plate, and, likewise, a connecting rod can be placed in the forward rod bore of the first longitudinal plate and a second connecting rod can be placed in the distal rod bore of second longitudinal plate to similarly assemble the bone plate. In these, and other, embodiments, one or more ends of the connecting rod may be threaded to mate with a threaded rod bore and, also, the connecting rod may have one or more retaining pin holes to mate with retaining pins which translate through retaining pin bores in the longitudinal plates and/or center plates, and the retaining pins and retaining pin holes and retaining pin bores may be threaded.
In the embodiment shown in
The longitudinal plates may have alternate configurations proximate to or as part of the first end of the longitudinal plate, such as an “L-shape”, “T-shape” and ‘Y-shape”, as described with respect to the first ends of certain longitudinal plates described in the inventors' co-pending patent application entitled ADJUSTABLE BONE PLATE filed on Oct. 24, 2005 under the Patent Cooperation Treaty in the United States Receiving Office (serial number not yet assigned) which is a Continuation-in-Part of U.S. patent application Ser. No. 10/975,296 filed Oct. 28, 2004. Both of these applications are incorporated by reference herein in their entirety.
As shown in
In an embodiment of the invention, as shown in
Referring to
Referring to
The center plate comprises at least one protrusion at either the first end or second end. As such, at least either the first end or the second end may have a recessed edge and a protrusion. In an embodiment of the invention, each end of the center plate comprises a recessed edge and a protrusion. Each protrusion comprises an inward wall adjacent to the recessed edge, an end wall adjacent to the inward wall, which may be about perpendicular, or perpendicular to the inward wall, and an outward wall which is adjacent to the end wall, with the outward wall generally parallel to the inward wall and are generally extensions of the forward longitudinal side or distal longitudinal side.
Referring to the
The center plate comprises one or more rod bores, which are generally defined by at least rod bore walls and also may be further defined by rod bore ends. In an embodiment of the invention, the center plate may comprise continuous rod bores such as a forward continuous rod bore proximate to the forward side of the center plate having a first opening at the first end of the center plate and a second opening at the second end of the center plate. The forward continuous rod bore is generally defined by a forward continuous rod bore wall, which may be cylindrical in shape, which extends from the first opening to the second opening of the forward continuous rod bore. Likewise, in an embodiment of the invention, the center plate also comprises a distal continuous rod bore proximate to distal side of the center plate having a first opening at the first end of the center plate and a second opening at the second end of the center plate. The distal continuous rod bore is generally defined by a distal continuous rod bore wall, which may be cylindrical in shape, which extends from the first opening to the second opening of the distal continuous rod bore. One or more of the rod bores may be threaded, i.e. have all or part of the rod bore inner wall with threaded sections, to mate with threaded connecting rods, for example one rod bore at the first end of the center plate may be threaded and one rod bore at the second end of the center plate may be threaded, or all the rod bores of the center plate may be threaded, including embodiments comprising threaded continuous rod bores.
In the preferred embodiment of the invention, the center plate comprises two or more first end rod bores which extend from the first end to a point between the first end and second end, which are defined by first end rod bore walls and a first end rod bore end walls and having openings at the first end and two or more second end rod bores which extend from the second end to a point a point between the first end and second end which are defined by second end rod bore walls and second end rod bore end walls and having openings at the second end.
As shown in the drawings, particularly
Except in the embodiments of the invention wherein the connecting rods are affixed to all rod bores at one or both ends of the center plate, the center plate comprises a first slit at the first end of the center plate and/or a second slit at the second end of the center plate. The first slit and second slit have the same shape, configuration and defining elements as described above with respect to the slit in the longitudinal plates.
As shown in
The second slit 334 has a second slit opening 342 at the second end and is defined by second slit upper wall 343 and a second slit lower wall 344 and a second slit end 345. The gap between the second slit upper wall 343 and second slit lower wall 344 and the second slit end 345 defines the second slit 334. The second slit end 345 is generally proximate to the second end bone screw bore 314c closest to the second locking means bore 313. The second slit 334 is preferably along the midline of each center section, the midline being the point about halfway between the top surface and a longitudinal plane of the lower surface 305 of the center plate. Optionally, the second slit comprises three sections, the first a forward section 346 which has a forward opening at the forward longitudinal side 306 and extends to a point on the second end forward bore 331, the second a central section 347 which extends from an opening on the second end forward bore, opposite to the point where the forward section intersects the second end forward bore to a point on the second end distal rod bore 332, and third, a distal section 360 which extends from an opening on the second end distal rod bore, opposite to the point where the central section intersects the second end distal rod bore, to the second end protrusion outward wall 326 and the distal wall 303.
In embodiments of the invention wherein the center-plate comprises a forward continuous rod bore and distal continuous rod bore, the sections of the first slit and second slit would be defined as discussed below, but with respect to the forward continuous rod bore and distal continuous rod bore as opposed to the first end forward rod bore, first end distal rod bore, second end forward rod bore and second end distal rod bore.
As shown in
As shown in
When a bone is fractured in two places, the surgeon may place one longitudinal plate over one side of one of the breaks, the center plate over the bone between breaks and the other longitudinal plate over the bone on the other side of the second break. The plates would be secured to the bone with one or more bone screws in each of the longitudinal plates and in the center plate. The breaks can be brought together by moving the longitudinal plates and/or center plates in a direction to move the bone together, and then the longitudinal plates and/or center plates can be fixed in location by applying the large top set screw. The surgeon then applies more bone screws through available bone screw bores, if desired. Various lengths of connecting rods may be used to further accommodate breaks in two or more places in the bone of a patient, and also to accommodate use of the center plates comprising continuous connecting rod bores. It should be understood that one or more center plates may be used in which case the bone plate would have three or more observation windows. Thus, the invention encompasses plates having more than one center plate with two longitudinal plates which comprise two or more observation windows, or a number of observation windows equal to one plus the number of center plates. Bone plates having more than one center plate are particularly useful when used to treat multiple fractures by providing an observation window over each fracture area.
The ends of the center plates comprise protrusions and, when assembled as part of a bone plate with longitudinal plates and, optionally, other center plates, the protrusions at the ends of the center plates have inward walls that are juxtaposed with the inward walls of the protrusions of adjoining longitudinal plates and/or center plates. This arrangement provides the same benefits as discussed above with respect to the embodiment of the invention wherein the bone plate assembly comprises two longitudinal plates with off-set protrusions.
In an embodiment of the invention, the bone screws may further set the longitudinal plates, and when used, the center plate(s), in place by urging the connecting rods towards the distal side and/or forward side of the longitudinal plate or center plate. The recessed section of the connecting rods may be placed adjacent to, or, preferably, partially within one or more of the bone screws bores, preferably the upper segment of the bone screw bore and/or frustoconical segment of the bone screw bore such that the recessed section partially overlays the bone screw bore and when the bone screw is inserted into the bone screw bore and translates through the bone screw bore, the connecting rod proximate to the lateral side is urged towards lateral side and the connecting rod proximate to the distal side is urged towards the distal side thereby increasing frictional forces between the connecting rods and the inner surfaces of the connecting rod bores. For example, in
Also, with respect to the large top set screws and bone screws, because the structure of the locking means bores and bone screws bores compliment the configuration of the large top set screws and bone screws, as discussed above, the large top set screw and bone screws are flush with the upper surface of the longitudinal plates and, when used, the center plate. Thus, the large top set screw and bone screw counter sink with the longitudinal plates and center plate and are recessed into the longitudinal plates and/or center plate(s). This will aid in precluding toggle and bone twisting.
In embodiments of the invention wherein both the distal connecting rod and forward connecting rod are both affixed to the same longitudinal plate or one or both ends of the center plate by either threaded connecting rods and/or connecting rods which comprise retaining pin holes for alignment with retaining pin bores in longitudinal plates or center plates which interact with retaining pins, all of which may be threaded, there is no need to use the locking means to releaseably secure the connecting rods to the longitudinal plate or center plate. Thus, in this embodiment of the invention, the locking means bore and slit, as well as the locking means, are not necessary for those particular longitudinal plates and center plates, or one or more ends of center plates, wherein two connecting rods are affixed. However, in embodiments wherein one connecting rod is affixed, either through connecting rods with threaded ends or with the use of the retaining pin hole and the other rod bore of the longitudinal plate or end of the center plate is vacant, then the longitudinal plate should comprise slit and locking means bore. With respect to the center plate, if both ends of the center plate have affixed connecting rods and no vacant rod bores then neither end would have a slit or locking means bore proximate thereto, if one end of the center plate has connecting rods affixed in both rod bores and the other end has at least one rod bore vacant then the end with vacant rod bore would comprise a slit and a locking means bore proximate thereto, and if both ends of the center plate have at least one vacant rod bore then both ends comprise the slit and a locking means bore proximate thereto.
The bone plates are generally assembled by translating the connecting rods within the connecting rod bores of the longitudinal plates and center plates. The locking means is inserted into the locking means bores of the longitudinal plates and, optionally, center plates and rotated such that the threaded section of the locking means mates with the threaded segment of the locking means bore causing the locking means to recess into the locking means bore as the locking means is moved in a direction. As the large top set screw moves downward, the upper wall of the slit is caused to move towards the lower wall of the slit thus creating a frictional force between the bore hole walls and the rods which restricts and precludes longitudinal movement of the longitudinal plates and center plates and/or the connecting rods thereby setting a longitudinal length of the bone plate. The lower wall of the slit may also be caused to move towards the upper wall fully or partially creating the frictional force. In effect, the locking mechanism crushes the slit and the locking means bores together to hold the longitudinal plates in fixed relationship to the rods. Because there is a gap between the ends of the longitudinal plates, and, if applicable, between the longitudinal plates and the center plates, these one or more gaps provide the surgeon with one or more windows to view the bone as he or she moves the bone plate together prior to selecting the appropriate therapeutic length.
The invention comprises a method for setting the broken bone of a patient. The method comprises providing one or more longitudinal plates and, optionally one or more center plates, providing one or more connecting rods, providing one or more locking means and providing one or more bone screws. The method further comprises securing at least a first longitudinal plate to the first side of the break in a bone of a patient by translating a bone screw through a bone screw bore and connecting the bone screw to the bone, inserting connecting rods into the connecting rod bores of the first longitudinal plate, placing a second longitudinal plate over the bone on the second side of a break in the bone of a patient and translating connecting rods through the bore holes in the second longitudinal plate, securing the second longitudinal plate to the bone by translating bone screws through a bone screw bore and connecting the bone screw to the bones, moving the longitudinal plates toward one another and providing and applying the locking means to set the length of the bone plate assembly. The method further comprises applying more bone screws by translating bone screws through further bone screw bores on the longitudinal plates. Optionally, the method may further comprise the steps of aligning slots in the connecting rods with the retaining pin bores and inserting retaining pins in the retaining pin bores and slots. Another optional embodiment of the invention involves translating one or more connecting rods having at least one end threaded into one or more threaded rod bores of one or more longitudinal plates and/or center plates. Yet a further embodiment comprises the step of aligning retaining pin holes in one or more connecting rods with retaining pin bores in one or more longitudinal plates and/or center plates and translating a retaining pin within the retaining pin bore and retaining pin hole. Preferably, the bone screws used prior to the step of applying the locking means are placed into and translated through bone screw bores which are not proximate to the connecting rods, i.e., bone screw bores in the longitudinal plates (or center plates) which are not adjacent to the recessed sections of the connecting rods and/or do not have the recessed section partially within the bone screw bores, then the bone screw bores adjacent to connecting rods and/or having connecting rods within may be used for the bone screws applied after the locking means is applied. In essence, the preferred method comprises initially anchoring longitudinal plates, and, optionally center plates as discussed below, into the bone, adjusting the longitudinal length of the bone plate assembly thereby moving the broken pieces of bone proximate to one another to set the bone in place and then compressing the longitudinal plates and optional center plate with the locking means.
The method may further comprise applying one or more center plates. In this embodiment, one center plate is placed over the second side of the break and additional connecting rods are used and inserted into the connecting rod bores on the second end of the center plate and then either additional center plates or the second longitudinal plate may be applied by translating the connecting rods from the second end of the center plate within the connecting rod bores of further center plates or the second longitudinal plate of the bone plate assembly. For example, the step of applying the center plate and additional connecting rods can be repeated over sides of broken bone by inserting the connecting rods, from the second end of the center plate into the first end of another center plate. The surgeon may either move and secure the longitudinal plate and center plate combination, or center plate and center plate combination either as each combination of pieces applied to the bone or after all pieces of the bone assembly are applied but before the locking means are applied. In any event, after the center plate is over the bone, the center plate may be secured to the bone by bone screws.
Methods wherein the connecting rods are permanently affixed to one or more longitudinal plates and/or center plates are also within the scope of the invention. Thus, rather than attaching longitudinal plates, then inserting connecting rods and then other longitudinal plates and/or center plate(s), the surgeon may attach a longitudinal plate and/or center plate with permanently affixed connecting rods then place a second center plate and/or a second longitudinal plate over the other side of the break and translate the permanently affixed connecting rods within the connecting rod bores of this adjoining center plate and/or longitudinal plate or may attach a first longitudinal plate and/or center plate to one side of the break and then translate the permanently affixed connecting rods of a second longitudinal plate and/or center plate within the connecting rod bores of the first longitudinal plate or center plate and then affix the second longitudinal plate or center plate on the bone on the opposite side of the break. In a preferred method, the surgeon affixes a connecting rod with either a threaded end or a retaining pin hole to either the forward rod bore or distal rod bore of a longitudinal plate or one end of a center plate leaving either the forward rod bore or distal rod bore of the longitudinal plate or end of a center plate vacant. The surgeon then affixes a connecting rod with either a threaded end or a retaining pin hole in the forward rod bore or distal rod bore of a second longitudinal plate or end of a center plate leaving the forward rod bore or distal rod bore of the second longitudinal plate and/or end of center plate vacant. The surgeon can then place the first longitudinal plate or center plate over one side of the broken bone and the second longitudinal plate or center plate over another side of the broken bone and translate the connecting rod from one longitudinal plate or center plate in the vacant rod bore of the opposite longitudinal plate or center plate. For example, when the bone plate assembly comprises a first longitudinal plate and a second longitudinal plate, a connecting rod would be affixed to the forward rod bore of the first longitudinal plate and a connecting rod would be affixed to the distal rod bore of the second longitudinal plate or the connecting rod would be affixed to the distal rod bore of the first longitudinal plate and the forward rod bore of the second longitudinal plate.
The surgeon moves the longitudinal plates and/or center plates to move the broken bones together for healing. The surgeon shall observe the bone pieces through the one or more observation windows, such as the observation windows defined by the connecting rods and all or some of 1) the second ends of the longitudinal plates, 2) the second end of a longitudinal plate and first end of a center plate, 3) the second end of a longitudinal plate and second end of a center plate and 4) the first end of a center plate and second end of a center plate. Further, the longitudinal plates and center plates described herein may be used with longitudinal plates and center plates which do not have the protrusion, such as those described in the inventors' co-pending applications for ADJUSTABLE BONE PLATE, which are the PCT application filed Oct. 24, 2005 and U.S. patent application Ser. No. 10/975,296 filed Oct. 28, 2004.
The assembled bone plates and the longitudinal plates and center plates of the invention may be constructed of any suitable biocompatible material, known to have sufficient structural strength and durability, such as stainless-steel, or titanium alloys. One example of such a material is ASTM F-136 titanium alloy (Ti 6AL-4V), which is a titanium alloyed with vanadium, or all ASTM materials. In addition the bone plate assembly and the longitudinal plates and center plates may be made of polymeric material such as PEEK (poly ethyl ethylketone), either separately or with other polymers or with other materials, such as reinforcing material. The material should have sufficient flex to mimic the micromotion of normal bone, to stimulate bone growth. Other materials which may be used are ceramic filled biocompatible polymers, or other biocompatible materials of sufficient strength to stabilize the bone during healing, or correct a fracture of the bone.
The bone plate assembly, the longitudinal plates and/or center plates may further comprise bioabsorbable drug delivery devices, such as implantable modular drug delivery devices. Examples of bioabsorbable drug delivery devices which may be used in the bone plate assembly, longitudinal plates and/or center plates are described in the co-pending application, U.S. Ser. No. 11/135,256 filed May 23, 2005, IMPLANTABLE PROSTHETIC DEVICES CONTAINING TIMED RELEASE THERAPEUTIC AGENTS, which is incorporated herein in its entirety by reference. Such devices, for example, may be placed within a dedicated bore, such as a drug delivery bore or pockets for drug or nano release, in one or more of the longitudinal plates and/or center plates, or within a bone screw bore or locking means bore of one or more of the longitudinal plates and/or center plates.
Bioabsorbable surgical fasteners or bone screws made from bioabsorbable materials may be used to apply the bone plate assembly, i.e. to apply the longitudinal plates and/or center plates, to the bone of a patient. For example, the materials described in the co-pending patent application, U.S. Ser. No. 11/025,231, filed Dec. 29, 2004, SURGICAL FASTENERS AND RELATED IMPLANT DEVICES HAVING BIOABSORBABLE COMPONENTS, which is incorporated herein in its entirety by reference, may be used for the bone screws and the bone screws may be the surgical fasteners described in this co-pending patent application.
