Abstract:
An osteotomy implant for supporting an open wedge osteotomy and method of use are described. In one form, the implant is configured to contain a graft material within the osteotomy. In another form, the implant is composed of multiple parts capable of being assembled either before or after insertion into the osteotomy.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATIONS 
     This patent application: 
     (i) is a continuation-in-part of pending prior U.S. patent application Ser. No. 11/047,159, filed Jan. 31, 2005 by Vincent P. Novak for OPEN WEDGE OSTEOTOMY SYSTEM AND SURGICAL METHOD; 
     (ii) is a continuation-in-part of prior U.S. patent application Ser. No. 11/047,551, now U.S. Pat. No. 8,083,746 filed Jan. 31, 2005 by Vincent P. Novak for OPEN WEDGE OSTEOTOMY SYSTEM AND SURGICAL METHOD; and 
     (iii) claims benefit of pending prior U.S. Provisional Patent Application Ser. No. 60/651,304, filed Feb. 9, 2005 by Vincent P. Novak et al. for OPEN WEDGE OSTEOTOMY SYSTEM AND SURGICAL METHOD. 
     The three above-identified patent applications are hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to surgical methods and apparatus in general, and more particularly to surgical methods and apparatus for performing open wedge osteotomies of the knee. 
     BACKGROUND OF THE INVENTION 
     Osteotomies of the knee are an important technique for treating knee osteoarthritis. In essence, knee osteotomies adjust the geometry of the knee joint so as to transfer weight bearing load from arthritic portions of the joint to the relatively unaffected portions of the joint. 
     Most knee osteotomies are designed to modify the geometry of the upper tibia, so as to adjust the manner in which the tibia engages the femur and hence the locations at which the load is transferred across the joint. 
     There are essentially two ways in which to adjust the orientation of the tibia: (i) the closed wedge technique; and (ii) the open wedge technique. 
     With the closed wedge technique, a wedge of bone is removed from the tibia, and the portions on either side of the resulting gap are brought together, whereby to reorient the tibial plateau and hence adjust the manner in which the tibia engages the femur. 
     With the open wedge technique, a cut is made into the tibia, the portions on either side of the cut are moved apart so as to form a wedge-like opening in the bone, and then the bone is secured in this position (e.g., by screwing metal plates to the bone or by inserting a wedge-shaped implant into the opening in the bone), whereby to reorient the tibial plateau and hence adjust the manner in which the tibia engages the femur. 
     While both closed wedge osteotomies and open wedge osteotomies provide substantial benefits to the patient, they are procedurally challenging to the surgeon. Furthermore, with respect to open wedge osteotomies, the wedge-shaped implants currently used are relatively large and awkward to position, and do not lend themselves to minimally invasive procedures, among other things. 
     The present invention is directed to open wedge osteotomies, and to wedge-shaped implants for positioning in the osteotomy opening. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a novel method and apparatus for effecting an open wedge osteotomy. More particularly, the present invention comprises the provision and use of a novel multi-part implant for use in an open wedge osteotomy. 
     In one form of the present invention, there is provided an osteotomy implant for supporting an open wedge osteotomy, the osteotomy implant comprising: 
     a first graft containment arm for disposition along one side of the open wedge osteotomy; 
     a second graft containment arm for disposition along a second, opposite side of the open wedge osteotomy; and 
     a base component for disposition along the mouth of the open wedge osteotomy, the base component being configured to selectively connect the first graft containment arm and the second graft containment arm to one another so as to form a generally wedge-shaped structure, wherein the base component constitutes the thicker end of the wedge. 
     In another form of the present invention, there is provided a method for conducting an open wedge osteotomy, comprising: 
     forming a wedge-like opening in the bone; 
     positioning a first graft containment arm along one side of the wedge-like opening, and positioning a second graft containment arm along a second, opposite side of the wedge-like opening; and 
     positioning a base component along the mouth of the wedge-like opening, the base component being selectively connected to the first graft containment arm and the second graft containment arm so as to form a generally wedge-shaped structure, wherein the base component constitutes the thicker end of the wedge. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein: 
         FIGS. 1 and 2  are schematic views showing the formation of the wedge-like opening in the tibia for an open wedge osteotomy; 
         FIGS. 3-10  are schematic views showing various multi-part implants with tab and slot interface construction; 
         FIGS. 11-18  are schematic views showing various multi-part implants with wedge and groove interface construction; 
         FIGS. 19-26  are schematic views showing various multi-part implants with ball and socket interface construction; and 
         FIGS. 27-34  are schematic views showing various multi-part implants with flat-to-flat interface construction. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Forming the Wedge-Like Opening in the Tibia 
     Looking first at  FIGS. 1 and 2 , there is shown a knee joint  5  upon which an open wedge osteotomy is to be performed. Knee joint  5  generally comprises a tibia  10  and a femur  15 . In accordance with the present invention, the open wedge osteotomy is effected by first making a cut  20  ( FIG. 1 ) into the upper tibia, and then moving apart the portions of the bone on either side of cut  20  so as to form a wedge-like opening  25  ( FIG. 2 ) in the bone, with the wedge-like opening  25  being configured such that the tibial plateau  30  is given the desired orientation relative to femur  15 . Cut  20  and wedge-like opening  25  may be formed in a variety of ways well known in the art. In one preferred form of the invention, cut  20  and wedge-like opening  25  are formed using an antero-medial approach, preferably with a minimally invasive technique. 
     In accordance with the present invention, once the desired wedge-like opening  25  has been formed in tibia  10  and tibial plateau  30  given its desired orientation, a novel multi-part implant is positioned in wedge-like opening  25  so as to maintain the reconfigured geometry of the tibia while weight bearing load is applied and healing occurs. 
     The Novel Multi-Part Implant in General 
     In accordance with the present invention, the novel implant comprises a multi-part construction having a generally wedge-shaped configuration substantially corresponding to the geometry of the wedge-shaped opening  25 . The various components of the multi-part implant are intended to be assembled together, preferably in-situ, so as to form the complete wedge-shaped implant. The multi-part construction of the implant is significant and provides numerous advantages over prior art implants. 
     First, the multi-part construction permits patient-specific sizing of the implant with reduced inventory requirements. In addition, if desired, the implant can be trimmed on-site, in the operating room, to even more precisely approximate the geometry of wedge-shaped opening  25 . 
     Second, the multi-part construction of the new implant permits the various component parts to be separately introduced into wedge-shaped opening  25 , with the parts thereafter being connected together so as to form the complete implant. Since each of the component parts is relatively small, they are easy to manipulate and, as such, can be more precisely placed in position. 
     Third, the multi-part approach facilitates use of the implant with minimally invasive procedures. 
     Multi-Part Implant with Tab and Slot Interface Construction 
     Looking next at  FIGS. 3 and 4 , in one preferred form of the invention, there is provided a novel implant  100  which generally comprises a base  105 , a first graft containment arm  110  and a second graft containment arm  115 . Base  105 , first graft containment arm  110  and second graft containment arm  115  are intended to be attached together, preferably in-situ, so as to collectively form a generally wedge-shaped structure, with base  105  constituting the thicker end of the wedge. In the case where wedge-shaped opening  25  is formed using an antero-medial approach (e.g., such as that shown in  FIG. 3 ), so that implant  100  is positioned using an antero-medial approach, first graft containment arm  110  is disposed in the posterior position, second graft containment arm  115  is disposed in the anterior position, and base  105  is disposed in the antero-medial position, with base  105  extending between and connecting together posterior graft containment arm  110  and anterior graft containment arm  115 . In this setting, posterior graft containment arm  110  and anterior graft containment arm  115  are preferably disposed substantially parallel to one another, intersecting the antero-medial base  105  at non-right angles (see  FIG. 3 ), or as otherwise appropriate for the anatomy. Furthermore, in this setting, posterior graft containment arm  110  is longer than anterior graft containment arm  115 . 
     In this form of the invention, base  105 , first graft containment arm  110  and second graft containment arm  115  are attached together using a tab and slot interface construction, with the first graft containment arm  110  having a first male (tab) member  120  which is received by a first female (slot) recess  125  formed in base  105 , and with the second graft containment arm  115  having a second male (tab) member  130  which is received by a second female (slot) recess  135  formed in base  105 . If desired, first male member  120  may form a friction fit in first female recess  125 , and/or second male member  130  may form a friction fit in second female recess  135 . 
     If desired, the various components of wedge-shaped implant  100  may be provided with barbs, ridges, projections, roughening, etc., as generally indicated at B (shown in  FIG. 4  but omitted from  FIG. 3  for the sake of clarity), so as to enhance engagement between the implant components and the bone. 
     In use, the wedge-shaped implant  100  is positioned in wedge-like opening  25  in tibia  10  so as to stabilize the tibia with the desired geometry while healing occurs. To this end, an appropriately sized base  105 , an appropriately sized first graft containment arm  110  and an appropriately sized second graft containment arm  115  are selected from a library of parts, preferably provided to the surgeon in kit form. If desired, the selected parts can be further sized to a desired dimension, e.g., by cutting. In the setting of an antero-medial approach, deployment of implant  100  may be effected by first appropriately positioning posterior graft containment arm  110  and anterior graft containment arm  115  in wedge-like opening  25 , and then connecting them together with base  105 . As this occurs, posterior graft containment arm  110 , anterior graft containment arm  115  and base  105  form a generally U-shaped perimeter which can contain bone paste, bone cement, other bone graft materials or the like within the interior of wedge-like opening  25 , whereby to facilitate healing. One or more bone screws  140 , installed through openings  145 , can be used to screw base  105  to the tibia. 
     If desired, the first graft containment arm and the second graft containment arm may be joined together by a bridge so as to form a single unit. More particularly, and looking now at  FIGS. 5 and 6 , there is shown a novel implant  100 A which comprises a base  105 A, a first graft containment arm  110 A, a second graft containment arm  115 A, and a bridge  150 A connecting together first graft containment arm  110 A and second graft containment arm  115 A. Again, base  105 A, first graft containment arm  110 A and second graft containment arm  115 A are attached together using a tab and slot interface construction, with the first graft containment arm  110 A having a first male (tab) member  120 A which is received by a first female (slot) recess  125 A formed in base  105 A, and with the second graft containment arm  115 A having a second male (tab) member  130 A which is received by a second female (slot) recess  135 A formed in base  105 A. If desired, first male member  120 A may form a friction fit in first female recess  125 A, and/or second male member  130 A may form a friction fit in second female recess  135 A. Again, a screw  140 A, received through an opening  145 A in base  105 A, may be used to screw base  105 A to the tibia. If desired, the various components of wedge-shaped implant  100 A may be provided with barbs, ridges, projections, roughening, etc., as generally indicated at B (shown in  FIG. 6  but omitted from  FIG. 5  for the sake of clarity), so as to enhance engagement between the implant components and the bone. 
     If desired, the positions of the tabs and slots can be reversed, i.e., with the base having a first male (tab) member which is received in a first female (slot) member formed in the first graft containment arm, and with the base having a second male (tab) member which is received in a second female (slot) member formed in second graft containment arm. More particularly, and looking now at  FIGS. 7 and 8 , there is shown a novel implant  100 B which is substantially the same as implant  100  described above, except that the position of the tabs and slots is reversed; and in  FIGS. 9 and 10 , there is shown a novel implant  100 C which is substantially the same as implant  100 A described above, except that the position of the tabs and slots is reversed. 
     Multi-Part Implant with Wedge and Groove Interface Construction 
     Looking next at  FIGS. 11 and 12 , in one preferred form of the invention, there is provided a novel implant  200  which generally comprises a base  205 , a first graft containment arm  210  and a second graft containment arm  215 . Base  205 , first graft containment arm  210  and second graft containment arm  215  are intended to be attached together, preferably in-situ, so as to collectively form a generally wedge-shaped structure, with base  205  constituting the thicker end of the wedge. In the case where wedge-shaped opening  25  is formed using an antero-medial approach (e.g., such as that shown in  FIG. 11 ), so that implant  200  is positioned using an antero-medial approach, first graft containment arm  210  is disposed in the posterior position, second graft containment arm  215  is disposed in the anterior position, and base  205  is disposed in the antero-medial position, with base  205  extending between and connecting together posterior graft containment arm  210  and anterior graft containment arm  215 . In this setting, posterior graft containment arm  210  and anterior graft containment arm  215  are preferably disposed substantially parallel to one another, intersecting the antero-medial base  205  at non-right angles (see  FIG. 11 ), or as otherwise appropriate for the anatomy. Furthermore, in this setting, posterior graft containment arm  210  is longer than anterior graft containment arm  215 . 
     In this form of the invention, base  205 , first graft containment arm  210  and second graft containment arm  215  are attached together using a wedge and groove interface construction, with the first graft containment arm  210  having a first male (wedge) member  220  which is received by a first female (groove) recess  225  formed in base  205 , and with the second graft containment arm  215  having a second male (wedge) member  230  which is received by a second female (groove) recess  235  formed in base  205 . If desired, first male member  220  may form a friction fit in first female recess  225 , and/or second male member  230  may form a friction fit in second female recess  235 . 
     If desired, the various components of wedge-shaped implant  200  may be provided with barbs, ridges, projections, roughening, etc., as generally indicated at B (shown in  FIG. 12  but omitted from  FIG. 11  for the sake of clarity), so as to enhance engagement between the implant components and the bone. 
     In use, the wedge-shaped implant  200  is positioned in wedge-like opening  25  in tibia  10  so as to stabilize the tibia with the desired geometry while healing occurs. To this end, an appropriately sized base  205 , an appropriately sized first graft containment arm  210  and an appropriately sized second graft containment arm  215  are selected from a library of parts, preferably provided to the surgeon in kit form. If desired, the selected parts can be further sized to a desired dimension, e.g., by cutting. In the setting of an antero-medial approach, deployment of implant  200  may be effected by first appropriately positioning posterior graft containment arm  210  and anterior graft containment arm  215  in wedge-like opening  25 , and then connecting them together with base  205 . As this occurs, posterior graft containment arm  210 , anterior graft containment arm  215  and base  205  form a generally U-shaped perimeter which can contain bone paste, bone cement, other bone graft materials or the like within the interior of wedge-like opening  25 , whereby to facilitate healing. One or more bone screws  240 , installed through openings  245 , can be used to screw base  205  to the tibia. 
     If desired, the first graft containment arm and the second graft containment arm may be joined together by a bridge so as to form a single unit. More particularly, and looking now at  FIGS. 13 and 14 , there is shown a novel implant  200 A which comprises a base  205 A, a first graft containment arm  210 A, a second graft containment arm  215 A, and a bridge  250 A connecting together first graft containment arm  210 A and second graft containment arm  215 A. Again, base  205 A, first graft containment arm  210 A and second graft containment arm  215 A are attached together using a wedge and groove interface construction, with the first graft containment arm  210 A having a first male (wedge) member  220 A which is received by a first female (groove) recess  225 A formed in base  205 A, and with the second graft containment arm  215 A having a second male (wedge) member  230 A which is received by a second female (groove) recess  235 A formed in base  205 A. If desired, first male member  220 A may form a friction fit in first female recess  225 A, and/or second male member  230 A may form a friction fit in second female recess  235 A. Again, a screw  240 A, received through an opening  245 A in base  205 A, may be used to screw base  205 A to the tibia. If desired, the various components of wedge-shaped implant  200 A may be provided with barbs, ridges, projections, roughening, etc., as generally indicated at B (shown in  FIG. 14  but omitted from  FIG. 13  for the sake of clarity), so as to enhance engagement between the implant components and the bone. 
     If desired, the positions of the wedges and grooves can be reversed, i.e., with the base having a first male (wedge) member which is received in a first female (groove) member formed in the first graft containment arm, and with the base having a second male (wedge) member which is received in a second female (groove) member formed in second graft containment arm. More particularly, and looking now at  FIGS. 15 and 16 , there is shown a novel implant  200 B which is substantially the same as implant  200  described above, except that the position of the wedges and grooves is reversed; and in  FIGS. 17 and 18 , there is shown a novel implant  200 C which is substantially the same as implant  200 A described above, except that the position of the wedges and grooves is reversed. 
     Multi-Part Implant with Ball and Socket Interface Construction 
     Looking next at  FIGS. 19 and 20 , in one preferred form of the invention, there is provided a novel implant  300  which generally comprises a base  305 , a first graft containment arm  310  and a second graft containment arm  315 . Base  305 , first graft containment arm  310  and second graft containment arm  315  are intended to be attached together, preferably in-situ, so as to collectively form a generally wedge-shaped structure, with base  305  constituting the thicker end of the wedge. In the case where wedge-shaped opening  25  is formed using an antero-medial approach (e.g., such as that shown in  FIG. 19 ), so that implant  300  is positioned using an antero-medial approach, first graft containment arm  310  is disposed in the posterior position, second graft containment arm  315  is disposed in the anterior position, and base  305  is disposed in the antero-medial position, with base  305  extending between and connecting together posterior graft containment arm  310  and anterior graft containment arm  315 . In this setting, posterior graft containment arm  310  and anterior graft containment arm  315  are preferably disposed substantially parallel to one another, intersecting the antero-medial base  305  at non-right angles (see  FIG. 19 ), or as otherwise appropriate for the anatomy. Furthermore, in this setting, posterior graft containment arm  310  is longer than anterior graft containment arm  315 . 
     In this form of the invention, base  305 , first graft containment arm  310  and second graft containment arm  315  are attached together using a ball and socket interface construction, with the first graft containment arm  310  having a first male (ball) member  320  which is received by a first female (socket) recess  325  formed in base  305 , and with the second graft containment arm  315  having a second male (ball) member  330  which is received by a second female (socket) recess  335  formed in base  305 . If desired, first male member  320  may form a friction fit in first female recess  325 , and/or second male member  330  may form a friction fit in second female recess  335 . 
     Significantly, the use of a ball and socket interface construction permits in-situ adjustment of the joinder angle between first graft containment arm  310  and base  305 , and in-situ adjustment of the joinder angle between second graft containment arm  315  and base  305 . This provides flexibility for addressing patient-specific variations in anatomy, and can significantly reduce inventory requirements. 
     If desired, the various components of wedge-shaped implant  300  may be provided with barbs, ridges, projections, roughening, etc., as generally indicated at B (shown in  FIG. 20  but omitted from  FIG. 19  for the sake of clarity), so as to enhance engagement between the implant components and the bone. 
     In use, the wedge-shaped implant  300  is positioned in wedge-like opening  25  in tibia  10  so as to stabilize the tibia with the desired geometry while healing occurs. To this end, an appropriately sized base  305 , an appropriately sized first graft containment arm  310  and an appropriately sized second graft containment arm  315  are selected from a library of parts, preferably provided to the surgeon in kit form. If desired, the selected parts can be further sized to a desired dimension, e.g., by cutting. In the setting of an antero-medial approach, deployment of implant  300  may be effected by first appropriately positioning posterior graft containment arm  310  and anterior graft containment arm  315  in wedge-like opening  25 , and then connecting them together with base  305 . As this occurs, posterior graft containment arm  310 , anterior graft containment arm  315  and base  305  form a generally U-shaped perimeter which can contain bone paste, bone cement, other bone graft materials or the like within the interior of wedge-like opening  25 , whereby to facilitate healing. One or more bone screws  340 , installed through openings  345 , can be used to screw base  305  to the tibia. 
     Again, the use of a ball and socket interface construction permits in-situ adjustment of the joinder angles between (i) first graft containment arm  310  and base  305 , and (ii) second graft containment arm  315  and base  305 . This provides flexibility for addressing patient-specific variations in anatomy, and can significantly reduce inventory requirements. 
     If desired, the first graft containment arm and the second graft containment arm may be joined together by a bridge so as to form a single unit. More particularly, and looking now at  FIGS. 21 and 22 , there is shown a novel implant  300 A which comprises a base  305 A, a first graft containment arm  310 A, a second graft containment arm  315 A, and a bridge  350 A connecting together first graft containment arm  310 A and second graft containment arm  315 A. Again, base  305 A, first graft containment arm  310 A and second graft containment arm  315 A are attached together using a ball and socket interface construction, with the first graft containment arm  310 A having a first male (ball) member  320 A which is received by a first female (socket) recess  325 A formed in base  305 A, and with the second graft containment arm  315 A having a second male (ball) member  330 A which is received by a second female (socket) recess  335 A formed in base  305 A. If desired, first male member  320 A may form a friction fit in first female recess  325 A, and/or second male member  330 A may form a friction fit in second female recess  335 A. Again, a screw  340 A, received through an opening  345 A in base  305 A, may be used to screw base  305 A to the tibia. If desired, the various components of wedge-shaped implant  300 A may be provided with barbs, ridges, projections, roughening, etc., as generally indicated at B (shown in  FIG. 22  but omitted from  FIG. 21  for the sake of clarity), so as to enhance engagement between the implant components and the bone. 
     If desired, the positions of the balls and sockets can be reversed, i.e., with the base having a first male (ball) member which is received in a first female (socket) member formed in the first graft containment arm, and with the base having a second male (ball) member which is received in a second female (socket) member formed in second graft containment arm. More particularly, and looking now at  FIGS. 23 and 24 , there is shown a novel implant  300 B which is substantially the same as implant  300  described above, except that the position of the balls and sockets is reversed; and in  FIGS. 25 and 26 , there is shown a novel implant  300 C which is substantially the same as implant  300 A described above, except that the position of the balls and sockets is reversed. 
     Multi-Part Implant with Flat-To-Flat Interface Construction 
     Looking next at  FIGS. 27 and 28 , in one preferred form of the invention, there is provided a novel implant  400  which generally comprises a base  405 , a first graft containment arm  410  and a second graft containment arm  415 . Base  405 , first graft containment arm  410  and second graft containment arm  415  are intended to be attached together, preferably in-situ, so as to collectively form a generally wedge-shaped structure, with base  405  constituting the thicker end of the wedge. In the case where wedge-shaped opening  25  is formed using an antero-medial approach (e.g., such as that shown in  FIG. 27 ), so that implant  400  is positioned using an antero-medial approach, first graft containment arm  410  is disposed in the posterior position, second graft containment arm  415  is disposed in the anterior position, and base  405  is disposed in the antero-medial position, with base  405  extending between and connecting together posterior graft containment arm  410  and anterior graft containment arm  415 . In this setting, posterior graft containment arm  410  and anterior graft containment arm  415  are preferably disposed substantially parallel to one another, intersecting the antero-medial base  405  at non-right angles (see  FIG. 27 ), or as otherwise appropriate for the anatomy. Furthermore, in this setting, posterior graft containment arm  410  is longer than anterior graft containment arm  415 . 
     In this form of the invention, base  405 , first graft containment arm  410  and second graft containment arm  415  are attached together using a flat-to-flat interface construction, with the first graft containment arm  410  having a first flat surface  420  which engages a first flat surface  425  formed in base  405 , and with the second graft containment arm  415  having a second flat surface  430  which engages a second flat surface  435  formed in base  405 . In one preferred construction (see  FIGS. 27 and 28 ), first flat surface  420  and second flat surface  430  are arranged so as to be outwardly facing, in the sense that they project away from the interior of the implant; and first flat surface  425  and second flat surface  435  are arranged so as to be inwardly facing, in the sense that they project toward the interior of the implant. 
     If desired, the various components of wedge-shaped implant  400  may be provided with barbs, ridges, projections, roughening, etc., as generally indicated at B (shown in  FIG. 28  but omitted from  FIG. 27  for the sake of clarity), so as to enhance engagement between the implant components and the bone. 
     In use, the wedge-shaped implant  400  is positioned in wedge-like opening  25  in tibia  10  so as to stabilize the tibia with the desired geometry while healing occurs. To this end, an appropriately sized base  405 , an appropriately sized first graft containment arm  410  and an appropriately sized second graft containment arm  415  are selected from a library of parts, preferably provided to the surgeon in kit form. If desired, the selected parts can be further sized to a desired dimension, e.g., by cutting. In the setting of an antero-medial approach, deployment of implant  400  may be effected by first appropriately positioning posterior graft containment arm  410  and anterior graft containment arm  415  in wedge-like opening  25 , and then connecting them together with base  405 . As this occurs, posterior graft containment arm  410 , anterior graft containment arm  415  and base  405  form a generally U-shaped perimeter which can contain bone paste, bone cement, other bone graft materials or the like within the interior of wedge-like opening  25 , whereby to facilitate healing. One or more bone screws  440 , installed through openings  445 , can be used to screw base  405  to the tibia. 
     If desired, the first graft containment arm and the second graft containment arm may be joined together by a bridge so as to form a single unit. More particularly, and looking now at  FIGS. 29 and 30 , there is shown a novel implant  400 A which comprises a base  405 A, a first graft containment arm  410 A, a second graft containment arm  415 A, and a bridge  450 A connecting together first graft containment arm  410 A and second graft containment arm  415 A. In one preferred construction (see  FIGS. 29 and 30 ), first flat surface  420 A and second flat surface  430 A are arranged so as to be outwardly facing, in the sense that they project away from the interior of the implant; and first flat surface  425 A and second flat surface  435 A are arranged so as to be inwardly facing, in the sense that they project toward the interior of the implant. Again, base  405 A, first graft containment arm  410 A and second graft containment arm  415 A are attached together using a flat-to-flat interface construction, with the first graft containment arm  410 A having a first flat surface  420 A which engages a first flat surface  425 A formed in base  405 A, and with the second graft containment arm  415 A having a second flat surface  430 A which engages a second flat surface  435 A formed in base  405 A. Again, a screw  440 A, received through an opening  445 A in base  405 A, may be used to screw base  405 A to the tibia. If desired, the various components of wedge-shaped implant  400 A may be provided with barbs, ridges, projections, roughening, etc., as generally indicated at B (shown in  FIG. 30  but omitted from  FIG. 29  for the sake of clarity), so as to enhance engagement between the implant components and the bone. 
     If desired, the positions of the flat surfaces can be reversed. More particularly, and looking now at  FIGS. 31 and 32 , there is shown a novel implant  400 B which is substantially the same as implant  400  described above, except that the positions of the flat surfaces is reversed (i.e., first flat surface  420 B and second flat surface  430 B are formed on base  405 B; and first flat surface  425 B and second flat surface  435 B are formed on posterior graft containment arm  410 B and anterior graft containment arm  415 B, respectively); and in  FIGS. 33 and 34 , there is shown a novel implant  400 C which is substantially the same as implant  400 A described above, except that the positions of the flat surfaces is reversed (i.e., first flat surface  420 C and second flat surface  430 C are formed on base  405 C; and first flat surface  425 C and second flat surface  435 C are formed on posterior graft containment arm  410 C and anterior graft containment arm  415 C, respectively). 
     OTHER CONFIGURATIONS 
     In addition to the foregoing, it should also be appreciated that, within a given construct, one graft containment arm might have a male connector (e.g., tab, wedge, ball, etc.) and the other graft containment arm might have a female connector (e.g., slot, groove, socket, etc.). 
     It should be also appreciated that the various interface constructions disclosed above may be modified by providing multiple engaging elements. 
     Thus, with the novel implant  100  shown in  FIGS. 3 and 4 , first graft containment arm  110  and second graft containment arm  115  could each be provided with multiple tabs, etc.; with novel implant  100 A shown in  FIGS. 5 and 6 , first graft containment arm  110 A and second graft containment arm  115 A could each be provided with multiple tabs, etc.; with novel implant  100 B shown in  FIGS. 7 and 8 , first graft containment arm  110 B and second graft containment arm  115 B could each be provided with multiple slots, etc.; with the novel implant  100 C shown in  FIGS. 9 and 10 , first graft containment arm  110 C and second graft containment arm  115 C could each be provided with multiple slots, etc. 
     And with the novel implant  200  shown in  FIGS. 11 and 12 , first graft containment arm  210  and second graft containment arm  215  could each be provided with multiple wedges, etc.; with novel implant  200 A shown in  FIGS. 13 and 14 , first graft containment arm  210 A and second graft containment arm  215 A could each be provided with multiple wedges, etc.; with novel implant  200 B shown in  FIGS. 15 and 16 , first graft containment arm  210 B and second graft containment arm  215 B could each be provided with multiple grooves, etc.; with the novel implant  200 C shown in  FIGS. 17 and 18 , first graft containment arm  210 C and second graft containment arm  215 C could each be provided with multiple grooves, etc. 
     And with the novel implants  400 ,  400 A,  400 B and  400 C, shown in  FIGS. 27-28 ,  29 - 30 ,  31 - 32  and  33 - 34 , respectively, multiple flat surfaces, set at various angles, may be provided on the elements. 
     In addition, where a graft containment arm has multiple connector elements thereon, those connector elements may be a combination of male (e.g., tab, wedge, ball, etc.), female (e.g., slot, groove, socket, etc.) and/or flat connectors. 
     Furthermore, the particular angles at which tabs, slots, wedges, grooves, flat surfaces, etc. are disposed may be varied as appropriate. 
     MATERIALS 
     It should be appreciated that the aforementioned implants may be formed out of various metals (e.g., titanium, stainless steel, etc.) or other biocompatible materials, including polymers, with the materials being absorbable or non-absorbable, osteoinductive or osteoconductive, etc. 
     Furthermore, it should be appreciated that different components of the multi-part implant may be formed out of different materials, depending on the function of the components. By way of example but not limitation, different components may have different formulations so as to provide different strength characteristics, different absorption rates, etc. 
     MODIFICATIONS 
     It will be understood that many additional changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principles and scope of the invention as expressed in the appended claims.