Abstract:
A bone plate has an upper surface, a lower surface, and at least one first hole extending through the upper and lower surfaces. The first hole has two or three vertically separate regions, each region communicating with or abutting an adjacent region. The first hole has a first unthreaded upper region, which has a curved inward taper from the plate&#39;s upper surface toward the plate&#39;s lower surface. The first hole has a second threaded middle region, which has a conical inward taper from the plate&#39;s upper surface toward the plate&#39;s lower surface. A third unthreaded lower region has a conical outward taper from the plate&#39;s upper surface toward the plate&#39;s lower surface. The bone plate may be straight, curved, or include a combination of both straight and curved segments.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation-in-part of U.S. patent application Ser. No. 10/843,113, filed on May 11, 2004, currently pending. The entire contents of this application is expressly incorporated herein by reference thereto. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to devices for bone fracture fixation and more specifically, to bone plates and systems for stabilization and/or compression of bone fractures. 
     BACKGROUND OF THE INVENTION 
     The use of bone plate and screw systems for treatment of bone fractures is widespread. Conventional bone plate and screw systems promote healing of a fracture by compressing the fracture ends together and drawing the bone fragments into close apposition with each other. If the plate is not provided with the appropriate hole types adapted to receive the proper screw types, then the angular relationships between the plate and screws may change postoperatively. This can lead to malalignment and poor clinical results. 
     Among the various different types of bone plate holes that are known in the art are the two different types of holes described below, each hole primarily intended for use with a different type of bone screw. 
     The first type of hole is a non-threaded relatively smooth hole, through which a screw with a smooth (non-threaded) head is inserted. These screws do not lock with the bone plate and are thus referred to as “non-locking” screws. Because non-locking screws do not lock with the plate hole, non-locking screws are not limited to a fixed angle with respect to the plate, but rather can be inserted at numerous angles. Inserting non-locking screws through the non-threaded plate holes and threading them into the bone effectively provides the desired compression of fracture ends. 
     The second type of hole is an internally threaded hole, which is adapted to mate with a screw having an externally threaded head. The threaded-head or “locking” screw is inserted at a fixed, predetermined angular relationship (determined by the central axis of the threaded hole) with respect to the bone plate. Locking screws, when mated with threaded bone-plate holes, possess high resistance to shear and torsional forces. Locking screws therefore resist loosening and thereby ensure stability between the screw and the bone plate. 
     Bone plates having both of the aforementioned types of holes are therefore desirable and are well known. Surgeons are limited, however, by the manufacturers&#39; placement of the varying holes on a given bone plate. A surgeon can achieve optimal compression when using a screw (e.g., a non-locking screw) without locking it to the plate. A surgeon can achieve desired stability between the screw, plate, and bone when using a locking screw with an internally-threaded hole. 
     It would thus be advantageous for a hole in a bone plate to be adapted to receive, at the surgeon&#39;s election, either non-locking screws for obtaining optimal compression or locking-screws for obtaining optimal stability, while minimizing any compromise in the strength of the bone plate. 
     SUMMARY OF THE INVENTION 
     The bone plate of present invention is a bone plate used for bone fracture fixation. Various embodiments of a bone plate having coaxial combination holes are described. 
     Among the various different types of bone plate holes that are known in the art are threaded holes and non-threaded holes. “Locking” screws (screws with threaded heads) are typically used with threaded holes. Locking screws, when mated with threaded holes, possess high resistance to shear and torsional forces and therefore ensure stability between the screw and bone plate. “Non-locking” screws are typically used with unthreaded holes and, unlike locking screws that mate with threaded holes, may be inserted at any one of a number of angles. Non-locking screws provide optimal compression of fractured ends. 
     A coaxial combination hole is, at once, adapted to receive (and utilize the benefits of) either a locking screw or non-locking screw. A coaxial combination hole is a hole which is threaded only partially through its length. In one preferred embodiment, the hole has a generally circular cross section with varying hole diameter. In a preferred embodiment, the hole has three regions: an upper region, a middle region, and a lower region. The upper region may be unthreaded and may have, in a direction from the plate&#39;s upper surface to its lower surface, a curved inward taper. The middle region may be threaded and may have, in a direction from the plate&#39;s upper surface to its lower surface, a conical inward taper. The lower region may be unthreaded and may have, in a direction from the plate&#39;s upper surface to its lower surface, an outward taper. 
     It will be appreciated that either type of the aforementioned screws may be used (and produce its intended results) with a coaxial combination hole. The threaded head of a threaded-head screw may mate with threaded middle region of the hole. Alternatively, a screw with an unthreaded head (or even a screw with a threaded head) may be inserted through a coaxial combination hole, without any mating of any threads, at any one of a number of angles. The outward taper of the coaxial combination hole&#39;s lower region provides room for the screw&#39;s shaft to be inserted at an angle (with respect to the center of the hole). Likewise the curved inward taper of the upper region of the hole provides a seat for the screw head to rest in, even when the screw is inserted at an angle. It will be appreciated, then, that at any given coaxial combination hole, a surgeon may elect to use either a screw for screw-plate stability or a screw for compression of fracture ends. 
     Coaxial combination holes may be placed in any type of bone plate. Coaxial combination holes provide multiple options for the surgeon. And because the holes do not require a larger cavity in the bone plate than would otherwise be necessary for an ordinary hole, the strength, size, and integrity of the bone plate are not compromised. Coaxial combination holes are therefore particularly useful in relatively small bone plates (e.g., pubic symphysis plates). 
     A coaxial combination hole has a central axis and a vertical axis. The hole&#39;s vertical axis is perpendicular to the plane formed by the plate&#39;s upper surface (if the plate has a straight upper surface), or to the plane that is tangential to the pinnacle of the plate&#39;s upper surface (if the plate is convex). A hole may have a central axis that is parallel to its vertical axis, or that is not parallel to its vertical axis (thereby biasing the shaft of the screw in one direction or another). A plate may have holes with any combination of foregoing hole orientations. 
     In preferred embodiments, bone plates have between 4 and 8 holes. In some embodiments, all plate holes are coaxial combination holes. In other embodiments, the bone plates may have some coaxial combination holes and at least one of another of a number of types of holes. One example of another type of hole is a dynamic compression (“DC”) hole. A dynamic compression hole may be an elongated hole having an oblique portion or ramp having an inclination such that when the ramp is engaged by the underside of the head of a screw, the bone plate is displaced in a direction to move the ramp away from the non-locking screw, causing the plate to apply a pressure to hold the fracture ends in contact or in tight engagement. Another example of another type of hole is a non-coaxial combination hole. A non-coaxial combination hole may be an elongated hole having a portion of its perimeter threaded and another portion of its perimeter unthreaded. In addition to, or in lieu of, the foregoing two examples, other types of holes may be formed in a bone plate having coaxial combination holes. 
     In one embodiment of the bone plate, the plate has a longitudinal axis, and has a straight center portion and curved ends. In one embodiment, the plate has two holes in the straight portion and two holes in each of the curved end portions. In one embodiment of this plate, all six holes may be coaxial combination holes. In another embodiment of this plate, the two holes on the straight portion may be either DC holes or non-coaxial combination holes, and the four holes on the curved end portions may be coaxial combination holes. In one embodiment of this plate, the width of the bone plate is narrower where there are no holes than where there are holes. 
     In another embodiment of the bone plate, the plate has a longitudinal axis and is straight. In one embodiment, the plate may have only coaxial combination holes, all of which may lie along the plate&#39;s longitudinal axis. 
     In another embodiment of the bone plate, the entire plate may be curved. In one embodiment, the plate may have only coaxial combination holes, all of which may lie along the plate&#39;s longitudinal axis (which runs along the center of the plate&#39;s width). 
     In the various embodiments, the plate&#39;s upper and lower surfaces may be straight or curved. In a preferred embodiment, the plate&#39;s upper surface may be convex, while the plate&#39;s lower surface may be concave. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These figures represent preferred embodiments of the present invention. Those skilled in the art will recognize that numerous variations and modifications may be made without departing from the scope of the present invention. Accordingly, it should be understood that these figures are not intended as limitations on the scope of the invention, which is defined only by the claims. 
         FIG. 1A  is a side cross-sectional view of a first embodiment of a bone plate having coaxial combination holes. 
         FIG. 1B  is a plan view of the bone plate of  FIG. 1A . 
         FIG. 1C  is a cross-sectional view of the bone plate of  FIG. 1A  taken along the cross section B-B. 
         FIG. 2A  is a side cross-sectional view of a second embodiment of a bone plate having coaxial combination holes and having dynamic compression holes. 
         FIG. 2B  is a plan view of the bone plate of  FIG. 2A . 
         FIG. 2C  is a cross-sectional view of the bone plate of  FIG. 2A  taken along the cross section B-B. 
         FIG. 3A  is a third embodiment of a bone plate having coaxial combination holes. 
         FIG. 3B  is a plan view of the bone plate of  FIG. 3A . 
         FIG. 4A  is a cross-sectional view of one embodiment of a coaxial combination hole. 
         FIG. 4B  is a magnified view of a portion of the thread of the coaxial combination hole of  FIG. 4A . 
         FIG. 5  is a cross-sectional view of a screw, having a threaded head, inserted through a coaxial combination hole. 
         FIG. 6A  is a cross-sectional view of a screw, having a non-threaded head, inserted through a coaxial combination hole at one angle. 
         FIG. 6B  is a cross-sectional view of a unthreaded-head screw inserted through a coaxial combination hole at an angle different from that of the screw of  FIG. 6A . 
         FIG. 7  is a plan view of a segment of a bone plate having non-coaxial combination holes. 
         FIG. 8  is a plan view of the bone plate of  FIGS. 3A and 3B , in a curved condition. 
         FIG. 9  is a side view of one embodiment of a screw that has a conically-tapered threaded head. 
         FIG. 10  is a side view of one embodiment of a screw having an unthreaded head. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is described below with reference to the preferred embodiments. Those skilled in the art will recognize that numerous variations and modifications may be made without departing from the scope of the present invention. Accordingly, it should be understood that the embodiments of the invention described below are not intended as limitations on the scope of the invention, which is defined only by the claims. 
     Reference is now made to  FIGS. 1A ,  2 A, and  3 A, which illustrate side, cross-sectional views of various embodiments of a bone plate. The bone plates may have at least one coaxial combination hole  90 , which has a length L that extends from the upper surface of the bone plate to the lower surface of the bone plate. The coaxial combination hole  90  is threaded only partially through the hole&#39;s length L. As such, with a given coaxial combination hole, a surgeon may elect to: (1) thread a screw having a thread on at least a portion of its head into and through the hole; or (2) insert a screw having an unthreaded head through the hole and into the bone. In a preferred embodiment, the hole  90  has length L of approximately 3.4 mm to 4.0 mm, which preferably corresponds to the thickness T of the bone plate. 
     Reference is now made to  FIGS. 1B ,  2 B, and  3 B, which illustrate plan views of various embodiments of the bone plate having at least one coaxial combination hole  90 . Each bone plate may have at least a central region with a longitudinal axis L-L. Each bone plate hole  90  may have a vertical axis V-V, which is perpendicular to the plane on which the plate&#39;s upper surface lies (if the plate has a straight upper surface), or to the plane that is tangential to the pinnacle of the plate&#39;s upper surface (if the plate is convex). (See  FIGS. 1A ,  2 A, and  3 A.) 
     Reference is now made to  FIGS. 1C and 2C , which illustrate cross-sectional views of the bone plates along the respective cross sections B-B. In a preferred embodiment, the upper surface of the plate may be convex and the lower surface of the plate may be concave, as shown in  FIGS. 1C and 2C . In a preferred embodiment, the radius of curvature for both surfaces may be from about 15 mm to about 35 mm, and preferably about 25 mm. In another embodiment, one or both of the plate surfaces may be flat. 
     As shown in  FIG. 1A , hole  90  may extend from the upper surface  20  to the lower surface  22  of the bone plate  10 . In one embodiment, the diameters of the hole  90  at its uppermost surface and its lower most surface may be equal or close to equal. The hole  90  may be widest at the uppermost surface  20  and lowermost surface  22  of the plate  10 . Each hole  90  may have a central axis C-C. (See  FIGS. 1A and 2A .) In some embodiments of the hole  90 , the central axis C-C of hole  90  may be parallel to the vertical axis V-V, as shown in  FIG. 3A  (central axis C-C not shown). In other embodiments, the central axis C-C of hole  90  will intersect with the vertical axis V-V at an angle θ, as shown in  FIGS. 1A and 2A . In preferred embodiments, the angle θ may vary from about 3° to about 17°, although other angles are contemplated. 
     As shown in  FIG. 4A , the hole  90  may have three regions: an upper region  92 , a middle region  94 , and a lower region  96 . The upper region  92  of the hole  90  may have an unthreaded inner surface  93  which, is preferably smooth, although texturing may be provided. In a preferred embodiment, the upper region  92  may have a curved inward taper, preferably concave, more preferably spherical, from the top surface of the plate to where the upper region  92  of the hole  90  meets the middle region  94 . The upper region  92  of the hole  90  is preferably narrowest where it meets the middle region  94 . Preferably, the upper region is approximately 1.0 mm to approximately 1.2 mm in length (along the axis C-C). In a preferred embodiment, the upper region may comprise about 25% to about 35% of the thickness T of the plate. In one embodiment, the diameter of the upper region  92 , at the region&#39;s broadest point, may be about 6 mm and, at the region&#39;s narrowest point, may be about 4 mm. In another embodiment the diameter of the upper region  92 , at the region&#39;s broadest point, may be about 8 mm and, at the region&#39;s narrowest point, may be about 6 mm. 
     The middle region  94  of the hole  90  may have a threaded inner surface  95 . In one embodiment, the threads have a pitch P (as shown in  FIG. 4B , which is a magnified partial view of the threaded surface  95 ) of approximately 0.3 mm to 0.5 mm. In a preferred embodiment, the thread angle γ may be approximately 50° to 70°, and preferably about 60°. In a preferred embodiment, the threaded region has at least one thread revolution, and preferably about three thread revolutions. Referring again to  FIG. 4A , the threaded inner surface  95  may, in a direction from the upper surface to the lower surface, have a conical inward taper. In a preferred embodiment, the threaded inner surface  95  may taper at an angle α of approximately 5° to 15°, and preferably approximately 10°. The middle region  94  may be the narrowest region (i.e., smallest-diameter region) of the hole  90 . In a preferred embodiment, the middle region  94  may be approximately 1.5 mm to approximately 1.9 mm in length (along the axis C-C). In a preferred embodiment, the middle region  94  may comprise about 40% to 50% of the thickness T of the plate. In one embodiment, the diameter of the middle region  94  may vary only slightly (due to the relatively shallow conical taper) and may be about 4 mm or, in another embodiment, about 6 mm. The diameter or taper of the middle region  94  may of course vary depending upon the size and/or taper of the screw. 
     The lower region  96  of the hole  90  may have an unthreaded inner surface  97  which is preferably smooth, although texturing may be provided. In a preferred embodiment, the lower region  96  may, from where it meets the middle region  94  to the lower surface of the plate, have a conical outward taper. In a preferred embodiment, the lower region  96  may taper outwardly at an angle β of approximately 35° to 55°, and preferably approximately 45°. In a preferred embodiment, the lower region  96  may be approximately 0.8 mm to approximately 1.2 mm in length (along the axis C-C). In a preferred embodiment, the lower region  96  may comprise about 20% to 35% of the thickness T of the plate. In one embodiment, the diameter of the lower region  96 , at the region&#39;s narrowest point, may be about 4 mm and, at the region&#39;s broadest point, may be about 6 mm. In another embodiment, the diameter of the lower region  96 , at the region&#39;s narrowest point, may be about 6 mm and, at the region&#39;s broadest point, may be about 8 mm. 
     Different types of screws may be used with the hole  90 . One type of screw is a screw that has a conically-tapered threaded head (shown in  FIG. 9 ). As shown in  FIG. 5 , the external threads of the screw&#39;s head may mate with the internal threads  95  of the middle region  94  of the hole  90 . This threaded-head screw  15  may be inserted at only one angle (with respect to the plate), which may be fixed by the threads  95  in the plate  10 . 
     A second type of screw that may be used with the hole  90  is a screw with a threaded shaft, but with an unthreaded head (shown in  FIG. 10 ). An unthreaded-head screw may be inserted into hole  90  at any one of a number of angles.  FIG. 6A  illustrates an unthreaded-head screw  17  inserted at an angle substantially perpendicular to the longitudinal axis of the plate  10 .  FIG. 6B  illustrates an unthreaded-head screw  17  inserted at a non-perpendicular angle with respect to the plate  10 . The conical outward taper (shown at surface  97 ) of the lower region  96  of the hole  90  provides room for screw shaft  18  to be inserted at an angle with respect to the center of the hole  90 . Likewise, the curved inward taper of the upper region  92  of the hole  90  provides a seat (at surface  93 ) for the screw head to rest in when an unthreaded-head screw  17  is inserted at an angle. A threaded-head screw may be used with a coaxial combination hole  90  in the same manner as the aforementioned unthreaded-head screw  17 . 
     Although virtually any type of bone plate may benefit from coaxial combination holes  90 , coaxial combination holes are particularly useful for pubic symphysis plates and other relatively small bone plates. (The pubic symphysis is the connection between the two halves of the pubis and may be damaged as a result of an accident.) Because a surgeon may elect to use either a locking screw or a non-locking compression screw with a coaxial combination hole, a bone plate having a coaxial combination hole may be more versatile than plates having other types of holes. The benefits may include: (1) a reduced need to manufacture many different plates having varying hole arrangement patterns; and (2) enhancement of clinical results. Because a coaxial combination hole does not require a substantially larger cavity in the bone plate than would otherwise be necessary for a simple hole, a coaxial combination hole provides desired flexibility for the surgeon without unduly compromising the strength, size, or integrity of the bone plate. Plates having coaxial combination holes may thus find particular utilization in pubic symphysis plates and other relatively small bone plates. 
     In one embodiment, the bone plate of the present invention may be a pubic symphysis plate as shown in  FIG. 1B , and may have a plurality of holes, all of which may be coaxial combination holes  90 . In one embodiment, the plate may have a length PL of approximately 70 mm to 90 mm. In one embodiment, the plate may have curved ends, as shown in  FIG. 1B , with a radius of curvature R. In a preferred embodiment, two coaxial combination holes  90  are located on the straight center portion of the plate. In a preferred embodiment, the plate ends may curve approximately at a 45 mm-55 mm radius R, spanning a 25°-35° angle δ. Preferably two coaxial combination holes  90  are placed along an arcs (on both sides of the plate&#39;s straight center portion) having a radius of curvature of about 50 mm. In a preferred embodiment, the hole  90  on the curved portion adjacent to the hole  90  on the straight portion is located approximately 12°-18° on the arc away from the hole  90  on the straight portion. Likewise, the two holes  90  on either curved portion may be placed along an arc approximately 12°-18° apart from each other. In a preferred embodiment, the plate may be symmetrical from one side to the other (i.e., a mirror hole arrangement on the other side of the plate is contemplated). In a preferred embodiment, the two holes near the center of the plate may lie along the longitudinal axis L-L of the center region of the plate  10 . The remaining holes may be offset from the longitudinal axis L-L, as shown in  FIG. 1B . 
     In a preferred embodiment, the central axes C-C of the holes  90  are not parallel to the respective vertical axes V-V of the holes  90 . In a preferred embodiment, as shown in  FIG. 1A , the two holes near the center of the plate have central axes C-C oriented to bias the tips of the screws in a direction away from the center of plate. In a preferred embodiment, the angle θ between each of these two central axes C-C and the vertical axes V-V is approximately 8° to 15°. In a preferred embodiment, as shown in  FIG. 1A , each of the holes  90 , that are located near the ends of the plate, has a central axis C-C oriented to bias the tips of the screws in a direction towards the center of plate. In a preferred embodiment the angle θ between each of these central axes C-C and the vertical axes V-V is approximately 4° to 10°. 
     In a preferred embodiment, the linear plate-surface distance d 1  between the edges of holes  90  may vary from hole to hole and may be approximately 10 mm to 12 mm. In a preferred embodiment, as shown in  FIG. 1B , there may be necking of the plate surface in between hole locations (i.e., the webs between the holes may be narrowed). This necking serves to achieve a desired balance between plate strength and plate size: plate strength is maximized, while plate size is minimized. In another embodiment the width of the plate between holes may be the same as the width of the plate where the holes are located. 
     In a preferred embodiment, the plate may have at least one hole  99 , preferably near the center of the plate. Holes  99  may aid in the placement of the plate onto the bone (e.g., for use with a guide wire) or may be provided as a suture hole. 
     Generally, for all embodiments, a shorter bone plate having only a few (e.g., 4) holes may be used when the fracture is relatively small or when the patient&#39;s bone or joint (e.g., pubic symphysis) being operated on is relatively small. 
     A plan view of a second embodiment of a pubic symphysis plate is shown in  FIG. 2B . The primary difference between this embodiment and the foregoing embodiment (which is illustrated in  FIGS. 1A and 1B ) is that the two holes near the center of the plate  30  of this embodiment are dynamic compression (“DC”) holes  70  instead of coaxial combination holes  90 . This embodiment of a bone plate is particularly useful when, to bring parts closer together, “extra” compression is desired. The DC holes are substantially similar to those disclosed in the specifications of United States publication No. 2002/0045901, in U.S. Pat. No. 6,669,701, and in reissued U.S. Pat. No. RE. 31,628, the contents of which are incorporated herein by reference. As shown in  FIG. 2B , DC hole  70  is elongated in a direction substantially aligned with the longitudinal axis L-L of the plate  30 . As shown in  FIG. 2B , DC hole  70  has an oblique portion or ramp  35  having an inclination such that when ramp  35  is engaged by the underside  13  of the head of a screw, preferably a screw having a head that is not threaded, and is preferably smooth and curved on the underside  13  which contacts the bone plate, the bone plate  30  is displaced in a direction to move ramp  35  away from the non-locking screw, causing the plate  30  to apply a pressure to hold the fracture ends in contact, preferably in engagement, along at least a portion of the fracture length. In a preferred embodiment, each of the holes  30  has a length X (illustrated in  FIG. 2A ) of approximately 6 mm to 7 mm. 
     Alternatively, the two holes near the center of the plate  30  may be non-coaxial combination holes  40  (instead of coaxial combination holes  90  or DC holes  70 ). The non-coaxial combination holes are substantially similar to those disclosed in the specifications of U.S. Pat. No. 6,669,701 and of United States publication No. 2002/0045901, the contents of which are hereby incorporated by reference. Reference is now made to  FIG. 7 .  FIG. 7  illustrates a bone plate having a plurality of combination holes  40 , which extend from the plate&#39;s upper surface to its lower surface. The holes  40  may be elongated (e.g., in a direction substantially aligned with a longitudinal axis of the plate) and may include a threaded portion  5  and a non-threaded portion  6 . The threaded portion  5  may extend over a range of greater than about 180° with respect to a center point C 1 . The threaded portion  5  of the hole  40  may be dimensioned and configured to engage a threaded head portion of a threaded-head bone screw, and fix the bone screw at a predetermined angle with respect to the bone plate. Preferably, the threaded portion  5  of the hole  40  extends through the full thickness of the bone plate (i.e., from the plate&#39;s upper surface to its lower surface) thus maximizing the stability of the bone screw to bone plate interface. A threaded-head screw or a non-threaded head screw may (e.g., for compression) pass through the non-threaded portion  6  of a combination hole  40 . 
     Another embodiment of a plate having coaxial combination holes is illustrated in  FIGS. 3A and 3B . In one embodiment, the plate  50  may have a plurality of holes, all of which may be coaxial combination holes  90 . Each of the holes  90  may lie along the longitudinal axis L-L of the plate  50 . In one embodiment, the central axis C-C of each of the holes  90  may be parallel to the corresponding vertical axis V-V of each of the holes  90 , as shown in  FIG. 3A  (central axis C-C not shown). In a preferred embodiment, the linear plate-surface distance d 2  between the edges of holes  90  may be approximately 6 mm to 9 mm. 
     A variation on the aforementioned embodiment (illustrated in  FIGS. 3A and 3B ) is illustrated in  FIG. 8 .  FIG. 8 . is the bone plate of  FIGS. 3A and 3B , in a “curved condition.” Though the bone plate of  FIGS. 3A and 3B  may be formed of such material to allow a surgeon to preoperatively bend the plate into a desired shape, a bone plate manufactured to a bend condition may be desirable. In the human body, a ball-and-socket joint is formed by the two acetabula of the pelvis and the head of each femur. The bone plate of  FIG. 9  may be especially useful for use on the posterior outer surface of a fractured acetabulum. The plate may have a radius of curvature R, which in a preferred embodiment, is about 100-115 mm. 
     While the present invention has been described with reference to the preferred embodiments, those skilled in the art will recognize that numerous variations and modifications may be made without departing from the scope of the present invention. Accordingly, it should be understood that the embodiments of the invention described above are not intended as limitations on the scope of the invention, which is defined only by the following claims.