Abstract:
An apparatus and method for treating a fracture of a bone is provided. A bone suture assembly includes a first bone plate positioned proximate to the bone. A suture is positioned through the first bone plate and across the fracture of the bone to thereby stabilize the fracture. A method of treating a fracture of a bone includes positioning at least one suture anchor proximate to the bone and positioning at least one bone plate between at least one suture anchor and the bone. The method also includes moving at least one suture across the fracture of the bone and through at least one bone plate, attaching at least one suture to at least one suture anchor, and tensioning at least one suture to stabilize the fracture of the bone.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application is a continuation of U.S. patent application Ser. No. 09/835,473 filed Apr. 16, 2001. The aforementioned application Ser. No. 09/835,473 is itself a continuation of U.S. patent application Ser. No. 09/532,942 filed Mar. 22, 2000, now U.S. Pat. No. 6,238,395. The aforementioned application Ser. No. 09/532,942 is itself a continuation of U.S. patent application Ser. No. 09/363,707 filed Jul. 29, 1999, now U.S. Pat. No. 6,045,551. The aforementioned application Ser. No. 09/363,707 is itself a continuation-in-part of U.S. patent application Ser. No. 09/323,488 filed Jun. 1, 1999, now U.S. Pat. No. 6,117,160. The aforementioned application Ser. No. 09/323,488 is itself a continuation of U.S. patent application Ser. No. 09/019,977 filed Feb. 6, 1998, now U.S. Pat. No. 5,921,986. The benefit of the earlier filing dates of the aforementioned applications and patents is claimed. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to a new and improved method and apparatus for securing sections of a fractured bone and/or securing body tissue to bone.  
           [0003]    When a bone is broken or fractured, it is necessary to press sections of the bone on opposite sides of the fracture together in order to promote healing of the bone. Bone screws have been used with or without metal plates to hold the sections of the fractured bone against movement relative to each other. In addition, it has been suggested that avulsion fractures could be treated by using wire sutures between sections of bone in a matter similar to that disclosed in U.S. Pat. No. 5,474,554. It has also been suggested that an anchor could be retained in a bone is a manner disclosed in U.S. Pat. Nos. 5,527,343 and 5,534,012.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention relates to a method of securing sections of a fractured bone. Sections of a fractured bone are held against movement relative to each other.  
           [0005]    In accordance with one aspect of the present invention, there is provided a bone suture assembly for treating a fracture of a bone. The bone suture assembly includes a first bone plate positioned proximate to the bone and a suture positioned through the first bone plate and across the fracture of the bone to thereby stabilize the fracture. The suture assembly may include a second bone plate positioned proximate to the bone generally opposite the first bone plate. The suture may be positioned through the second bone plate to stabilize the fracture. The suture assembly may also include a passage through the bone and across the fracture, wherein the suture is disposed within the passage. The passage may be nonlinear and may include a tubular member. The suture may be disposed within the tubular member.  
           [0006]    Furthermore, the bone suture assembly may include at least one fastener to hold the first bone plate to the bone. At least one fastener may extend across the fracture of the bone and may extend through the bone and through the second bone plate. At least one fastener may also include a screw and nut. Additionally, the suture assembly may include a tubular member in the bone positioned across the fracture, and the suture may be disposed within the tubular member. The tubular member may be packed with bone particles or bone osteoinductive protein.  
           [0007]    In accordance with another aspect of the present invention, the bone suture assembly includes a first suture anchor positioned proximate to the bone, a first bone plate positioned between the first suture anchor and the bone, and a suture positioned across the fracture of the bone to stabilize the fracture. The suture has a first end portion disposed through the bone plate and attached to the first suture anchor. The suture assembly may also include a second suture anchor positioned proximate to the bone generally opposite the first suture anchor. The second suture anchor may be attached to a second end portion of the suture.  
           [0008]    Moreover, the bone suture assembly may include a second bone plate positioned between the second suture anchor and the bone. The suture assembly may also include a passage through the bone and across the fracture, wherein the suture is disposed within the passage. In the present invention, the first and second suture anchors may be suture retainers which may have deformable material to hold the suture retainers to the suture.  
           [0009]    In accordance with still another aspect of the present invention, a method for treating a fracture of a bone is provided. The method includes positioning at least one suture anchor proximate to the bone, positioning at least one bone plate between at least one suture anchor and the bone, and moving at least one suture across the fracture of the bone and through at least one bone plate. The method also includes attaching at least one suture to at least one suture anchor and tensioning at least one suture to stabilize the fracture of the bone. At least one suture anchor may be a suture retainer.  
           [0010]    In addition, the method may include fastening at least one bone plate to the bone with at least one screw. At least one screw may have a length less than the diameter of the bone, and at least one screw may have a length greater than the diameter of the bone. At least one screw may include at least one nut, and at least one screw may extend across the fracture of the bone.  
           [0011]    Furthermore, the method may include forming at least one passage through the bone and moving at least one suture through at least one passage. Also, at least one suture attached to at least one suture anchor may be moved through at least one passage. The method may also include changing the orientation of at least one suture anchor from a first to a second configuration thereby causing at least one suture anchor to become proximate to the bone and impassable through at least one passage. Finally, the method may include tensioning at least one suture between at least two suture anchors to stabilize the fracture of the bone. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The foregoing and other features of the invention will become more apparent upon a consideration of the following description taken in connection with the accompanying drawings wherein:  
         [0013]    [0013]FIG. 1 is a schematic illustration of a bone having a fracture which has been treated with sutures and suture anchors;  
         [0014]    [0014]FIG. 2 is an enlarged fragmentary schematic sectional view of a portion of the bone of FIG. 1 and illustrating the manner in which a suture extends across the fracture and interconnects suture anchors on opposite sides of the fracture;  
         [0015]    [0015]FIG. 3 is a schematic illustration, generally similar to FIG. 2, illustrating the manner in which a suture retainer is used to maintain tension in a suture which extends across a fracture to a suture anchor;  
         [0016]    [0016]FIG. 4 is a schematic illustration, generally similar to FIGS. 2 and 3, illustrating the manner in which body tissue is connected with a bone using a suture and suture anchors;  
         [0017]    [0017]FIG. 5 is a schematic illustration, generally similar to FIGS.  2 - 4 , illustrating the manner in which a suture extends between suture anchors through a nonlinear passage;  
         [0018]    [0018]FIG. 6 is a schematic illustration, generally similar to FIG. 5, illustrating the manner in which a suture extends between a suture anchor and a suture retainer through a nonlinear passage;  
         [0019]    [0019]FIG. 7 is a schematic illustration depicting a bone which has been fractured in such a manner as to have a bone fragment connected with the bone by muscle or other fibrous tissue;  
         [0020]    [0020]FIG. 8 is a schematic illustration depicting the manner in which the bone fragment of FIG. 7 is connected to the bone by a suture and a pair of suture anchors;  
         [0021]    [0021]FIG. 9 is a schematic illustration depicting the manner in which a bone fragment is connected with a bone by a suture which extends between an anchor within the bone and an anchor which engages the bone fragment;  
         [0022]    [0022]FIG. 10 is a schematic illustration, generally similar to FIGS.  2 - 4 , illustrating in the manner in which plates and rigid fasteners are used in association with a suture and anchors to treat a bone fracture;  
         [0023]    [0023]FIG. 11 is a schematic illustration depicting the manner in which a thin elongated member is moved through bone and the manner in which a drill is moved along the thin elongated member to enlarge a passage formed in the bone by the thin elongated member;  
         [0024]    [0024]FIG. 12 is a schematic illustration depicting the manner in which an anchor is moved through a passage in the drill of FIG. 11 after the thin elongated member has been removed from the passage in the drill;  
         [0025]    [0025]FIG. 13 is a schematic illustration, generally similar to FIG. 2, illustrating the manner in which a tubular member is positioned in a passage in the bone;  
         [0026]    [0026]FIG. 14 is a schematic illustration, generally similar to FIG. 5, illustrating the manner in which tubular members are positioned in a nonlinear passage in a bone; and  
         [0027]    [0027]FIG. 15 is a schematic illustration, generally similar to FIG. 3, illustrating the manner in which a suture retainer is used with a tubular member which is positioned in a passage in a bone.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]    A bone  20  which has been fractured is illustrated in FIG. 1. The bone  20  is divided into two sections  22  and  24  by a fracture  26 . Opposite side surfaces  28  and  30  of the fracture  26  are pressed together by bone suture assemblies  32 .  
         [0029]    It should be understood that the bone suture assemblies  32  may be utilized in the treatment of any one of many different types of fractures. The fractures may or may not result in the formation of one or more bone fragments. In FIG. 1, the bone suture assemblies  32  have been illustrated as interconnecting sections  22  and  24  of a complete bone fracture of the spiral type. However, the bone suture assemblies  32  could be utilized to connect a fragment of a bone to the main portion of the bone from which the fragment was broken off.  
         [0030]    Each of the bone suture assemblies  32  has the same construction. However, the bone suture assemblies  32  could have different constructions if desired. The construction of one of the identical bone suture assemblies  32  is illustrated in FIG. 2.  
         [0031]    The bone suture assembly  32  (FIG. 2) includes a flexible suture  38  which extends across the fracture  26 . The suture  38  is disposed in a straight cylindrical passage  40  which extends diametrically across a generally cylindrical portion of the bone  20 . The passage  40  extends through hard compact tissue of an outer layer  42  of the bone and through spongy or cancellous bone tissue  44  which is enclosed by the hard outer layer. Although the passage  40  has a linear configuration, the passage could have a nonlinear configuration if desired.  
         [0032]    The suture  38  extends between a first suture anchor  50  disposed on one side of the fracture  26  and a second suture anchor  52  disposed on the opposite side of the fracture. Tension is maintained in the suture  38  to press the suture anchors  50  and  52  against opposite sides of the bone  20  with a predetermined force. This force presses the side surfaces  28  and  30  of the fracture  26  firmly together to promote healing of the fracture. If desired, buttons or other force distributing members could be provided between the anchors  50  and  52  and the bone  20 . Body tissue could be disposed between the anchors  50  and  52  and the bone  20 .  
         [0033]    The suture  38  and/or suture anchors  50  and  52  maybe formed of any desired natural or artificial material. For example, the suture  38  may formed of either a polymeric material or a metal. The suture  38  may be biodegradable. Any known suture material may be utilized to form the suture  38 .  
         [0034]    The suture anchors  50  and  52  have the same construction. However, the anchor  50  could have a construction which is different than the construction of the anchor  52 . The anchor  50  has a cylindrical outer side surface  56  which extends between smooth rounded end portions  58  and  60 . A pair of parallel cylindrical openings  64  and  66  extend diametrically through the anchor  50 . The anchor  50  is free of sharp corners or projections to avoid cutting or abrading of body tissue disposed adjacent to the anchor.  
         [0035]    The suture anchor  50  is made of a biocompatible material. Suitable materials include stainless steel or titanium, cobalt chrome and other biocompatible metals. Polymeric material may also be used, suitable polymeric materials includes polyethylene, polypropylene, and biodegradable material such as PLA and PGA. It is believed that it may be preferred to form the suture anchors  50  and  52  from biodegradable or bioerodible copolymers. If desired, the anchor  50  could be formed of body material or hydrophilic materials.  
         [0036]    It is contemplated that the anchor  50  may have any desired configuration. For example, the anchor  50  could have any one of the configurations disclosed in U.S. Pat. No. 5,522,846 issued Jun. 4, 1996 and entitled “Suture Anchor”. Alternatively, the suture anchor  50  could have the configuration disclosed in U.S. Pat. No. 5,534,012 issued Jul. 9, 1996 and entitled “Method and Apparatus for Anchoring a Suture”.  
         [0037]    Although the anchor  50  may have any desired configuration, the cross-sectional size of the anchor is such as to enable the anchor to be moved through the passage  40 . In addition, the length of the anchor  50  is such as to enable it to span an opening at an end of the passage  40  and transmit force from the suture  38  to a substantial area on the outer layer  42  of the bone  20 . It is believed that it will be preferred to form the anchor  50  in such a manner as to eliminate any sharp corners or projections.  
         [0038]    In the illustrated embodiment of the invention, the anchor  50  has a cylindrical configuration. This particular anchor has an axial length of about two millimeters and a diameter of about one millimeter. The length of the anchor  50  may be approximately three times the diameter of the anchor. The openings  64  and  66  have a diameter of about one-half millimeter.  
         [0039]    It should be understood that the foregoing dimensions have been set forth herein for purposes of clarity of description and it is contemplated that the size of the anchor  50  may vary as a function of the size of the bone being treated. Thus, relatively small anchors may be used in association with treatment of small bones in a wrist, hand, foot or ankle of a patient. Relatively large anchors may be used in association with treatment of larger bones in an arm, shoulder, leg or hip of a patient. It should be understood that the bone suture assembly  32  may be used in conjunction with many different bones other than the specific bones previously mentioned.  
         [0040]    Only a single anchor  50  or  52  has been shown at opposite ends of the passage  40 . It is contemplated that a plurality of anchors could be provided at each end of the passage  40 . For example, a pair of separate or interconnected anchors could be provided in a manner similar to that disclosed in the aforementioned U.S. Pat. No. 5,534,012.  
         [0041]    In the embodiment of the invention illustrated in FIG. 2, the suture  38  has a pair of limbs or sections  72  and  74  which extend through the openings  64  and  66  in the suture anchors  50  and  52 . A connector section  76  interconnects the two limbs  72  and  74  of the suture  38  and engages a portion of the anchor  50 . A knot  78  is formed in the opposite ends of the limbs  72  and  74  to interconnect the two limbs of the suture  38 .  
         [0042]    When the knot  78  is formed, a predetermined tension is present in the limbs  72  and  74  of the suture  38 . This results in the suture anchors  50  and  52  being pressed firmly against the bone  20  with a predetermined force. This predetermined force is maintained during and after tying of the knot  78 .  
         [0043]    When the bone suture assembly  32  is to be used to treat the fracture  26  in the bone  20 , the two sections  22  and  24  of the bone are pressed together at the fracture  26  to align the side surfaces  28  and  30  of the fracture. A drill is then used to form the passage  40  which extends diametrically through the generally cylindrical bone  20 . Of course, the passage  40  could be formed by the use of a tool other than a drill. If desired, the passage  40  could have a noncircular cross-sectional configuration.  
         [0044]    Once the passage  40  has been formed in the two sections  22  and  24  of the bone  20 , a tubular cylindrical member is inserted into the passage  40  and extends diametrically through the bone  20 . The leading end of the tubular cylindrical member is aligned with a circular outlet  84  from the passage  40 . The opposite end of the tubular member is aligned with a circular inlet  86  to the passage  40 . The tubular member has a thin cylindrical wall which engages the sections  22  and  24  of the bone  20 . A cylindrical inner side surface of the tubular member defines a passage having a diameter which is only slightly less than the diameter of the passage  40 .  
         [0045]    By inserting the tubular member into the passage  40 , the portions of the passage disposed on opposite sides of the fracture  26  are maintained in alignment. The tubular member may be flexible to enable the tubular member to be inserted into a nonlinear passage  40  through the bone  20 . The tubular member may be formed of metal or a polymeric material. If the tubular member is formed of a polymeric material, it may be preferred to form the tubular member from a biodegradable or bioerodible copolymer.  
         [0046]    The suture  38  is formed into a loop which extends through the openings  64  and  66  in the anchor  50 . At this time, the suture  38  has a length which is substantially greater than the length illustrated in FIG. 2. The cylindrical anchor  50 , with the suture  38  connected thereto, is then positioned in axial alignment with the tubular member which extends through the passage  40 . Thus, the anchor  50  is moved to an orientation in which a longitudinal central axis of the anchor is coincident with the longitudinal central axis of the cylindrical passage in the tubular member which extends through the passage  40  in the bone  20 .  
         [0047]    The leading end  58  of the anchor  50  is then moved into the cylindrical tubular member which forms a liner for the passage  40 . A pusher member pushes the anchor  50  from an upper (as viewed in FIG. 2) end of the tubular member along the passage  40  in the bone  20  and through the outlet  84  from the passage. As the anchor  50  moves through the passage  40 , the suture  38  is pulled through the passage  40  by the anchor.  
         [0048]    The orientation of the anchor  50  is then changed from an orientation in which the longitudinal central axis of the anchor  50  is aligned with the longitudinal central axis of the passage  40  to an orientation in which the longitudinal central axis of the anchor  50  extends generally perpendicular to the longitudinal central axis of the passage  40 , i.e., the orientation shown in FIG. 2. To pivot the anchor  50  to the orientation shown in FIG. 2, as the anchor emerges from the outlet  84 , the suture  38  is tensioned. The combination of the tension in the suture  38  and force applied against the trailing end  60  of the anchor by the pusher member causes the anchor to pivot about the trailing end  60  of the anchor. The pusher member is then withdrawn and the suture tensioned to move the anchor to the position shown in FIG. 2 in a manner similar to that described in the aforementioned U.S. Pat. Nos. 5,527,343 and 5,534,012.  
         [0049]    Although it is believed that it may be preferred to change the orientation of the anchor  50  after it has emerged from the passage  40 , the anchor could be blocked from reentering the passage in other ways if desired. Thus, the anchor could expand after emerging from the passage  40 . This could be accomplished by having spring biased arms held in a retracted position by engagement of spring biased arms with the inner side surface of the tubular cylindrical member which lines the passage  40 . Upon emerging from the passage, the arms would move outward under the influence of spring forces and extend radially outward beyond the edge of the exit from the passage  40 . If desired, the anchor  50  could be constructed so as to expand in a manner similar to that disclosed in U.S. Pat. No. 5,397,331 and/or U.S. Pat. No. 4,409,974.  
         [0050]    Rather than expanding under the influence of stored energy, such as spring force, the anchor  50  could expand by absorbing body fluids. Thus, the anchor  50  may be compressed when it moves through the passage  40  and will expand and absorb body fluids after emerging from the passage  40 . It is contemplated that the anchor  50  could be constructed so as to expand in any one of the ways disclosed in U.S. patent application Ser. No. 08/699,553 filed Aug. 19, 1996 by Peter M. Bonutti and entitled “Suture Anchor”.  
         [0051]    The cylindrical tubular member is then withdrawn from the passage  40 . It should be understood that the cylindrical tubular member is used to line the passage  40  in the bone  20  during movement of the anchor  50  through the passage. The use of the tubular member to line the passage  40  may be omitted if desired. However, if the use of the tubular member to line the passage  40  is omitted, the anchor  50  and pusher member would be exposed to the cancellous bone tissue  44  during movement of the anchor through the passage.  
         [0052]    The limbs  72  and  74  of the suture  38  are then threaded through openings  64  and  66  in the second suture anchor  52 . The limbs  72  and  74  of the suture  38  are tensioned and the second anchor  52  is pressed against the outer side surface of the bone  20 . While a predetermined tension force is maintained in the limbs  72  and  74  of the suture  38 , the knot  78  is tied in the suture to interconnect the two suture anchors  50  and  52  with the suture  38 . The suture  38  is then trimmed to the desired length.  
         [0053]    Once the knot  78  has been tied between the limbs  72  and  74  of the suture  38 , the tension in the suture  38  presses the side surfaces  28  and  30  of the fracture  26  together. This pressure between the side surfaces  28  and  30  of the fracture  26  is maintained by the suture  38  and suture anchors  50  and  52  until the fracture heals. It is believed that it may be preferred to form the suture  38  and suture anchors  50  and  52  of a biodegradable material which, after the fracture  26  has healed, will dissolve in the patient&#39;s body.  
         [0054]    The cylindrical tubular member which is inserted into the passage  40  through the bone  20  performs the dual functions of lining the inside of the passage  40  and maintaining the two sections  22  and  24  of the bone in alignment. The cylindrical tubular member could have a slot formed in a side wall of the tubular member to facilitate insertion of the tubular member into the passage  40 . It is contemplated that the cylindrical tubular member could be left in the passage  40  after the bone suture assembly  32  has been installed. If the slotted or unslotted cylindrical tubular member is to be left in the passage  40 , the cylindrical tubular member may be formed of a biodegradable or bioerodible copolymer. When the cylindrical tubular member remains in the passage  40 , the suture  38  extends through the tubular member.  
         [0055]    Although only a knot  78  has been shown in FIG. 2 adjacent to the second anchor  52 , a suture retainer could be provided to further hold the limbs  72  and  74  of the suture  38 . If a suture retainer is to be used in association with the knot  78 , the suture retainer will be moved along the limbs of the suture  38  toward the knot before the limbs  72  and  74  of the suture are trimmed to the short length shown in FIG. 2. The suture retainer would then be plastically deformed to grip the limbs  72  and  74  of the suture  38 . Thereafter, the suture limbs  72  and  74  would be trimmed to a desired length.  
       BONE SUTURE ASSEMBLY—SECOND EMBODIMENT  
       [0056]    In the embodiment of the invention illustrated in FIG. 2, a pair of suture anchors  50  and  52  are connected with the suture  38  to maintain tension in the suture and pressure against opposite side surfaces  28  and  30  of the fracture  26 . In the embodiment of the invention illustrated in FIG. 3, a suture retainer is used in place of one of the suture anchors. Since the embodiment of the invention illustrated in FIG. 3 is generally similar to the embodiment of the invention illustrated in FIG. 2, similar numerals will be utilized to designate similar components, the suffix letter “a” being associated with the embodiment of the invention illustrated in FIG. 3 to avoid confusion.  
         [0057]    A bone  20   a  has sections  22   a  and  24   a  which are separated by a fracture  26   a . The fracture  26   a  has side surfaces  28   a  and  30   a  which are pressed together by a bone suture assembly  32   a . A suture  38   a  extends through a cylindrical passage  40   a  which extends diametrically through the generally cylindrical bone  20   a . The suture  38   a  has a pair of limbs or sections  72   a  and  74   a  which are connected with a suture anchor  50   a . The suture anchor  50   a  has the same construction as the suture anchor  50  of FIG. 2.  
         [0058]    In accordance with a feature of this embodiment of the invention, a suture retainer  92  is used in place of the suture anchor  52  of FIG. 2. The suture retainer  92  has a spherical configuration. A cylindrical passage  94  extends through the center of the spherical suture retainer  92 . The sections  72   a  and  74   a  of the suture  38   a  extend around the spherical outer side surface of the suture retainer  92 . Thus, a loop is formed in each of the sections  72   a  and  74   a  around portions of the suture retainer  92 .  
         [0059]    If desired, the suture retainer  92  could have a different configuration. For example, the suture retainer  92  could have an oval or elliptical configuration. Although the passage  94  has a linear central axis, the passage could have a nonlinear central axis. If desired, a plurality of passages having the same or different configurations could be provided in the suture retainer  92 .  
         [0060]    After the suture  38   a  has been inserted through the suture retainer  92 , in the manner illustrated schematically in FIG. 3, the suture retainer  92  is moved along the sections  72   a  and  74   a  of the suture  38   a  toward the bone  20   a . The suture retainer  92  is formed as one piece of a polymeric material having a relatively low coefficient friction. Therefore, the two sections  72   a  and  74   a  of the suture  30   a  can readily slide along the surfaces of the suture retainer  52   a  while the suture retainer moves toward the bone  20   a.    
         [0061]    A predetermined tension is maintained in the sections  72   a  and  74   a  of the suture  38   a  while the suture retainer  92  is pressed against the bone  20   a . This results in the suture  38   a  being pulled tightly against the suture anchor  50   a . The tension in the suture  38   a  is effective to press the suture anchor  50   a  and retainer  92  against opposite sides of the bone  20   a  with a predetermined force.  
         [0062]    Once the suture retainer  92  has been moved along the suture  38   a  and is being pressed against the bone  20   a  with a predetermined force, the suture retainer is plastically deformed to grip the sections  72   a  and  74   a  of the suture  38   a . An apparatus  98  for pressing the suture retainer  92  against the bone  20   a  includes a tubular cylindrical plunger  102  (FIG. 3) having a cylindrical central passage through which the sections  72   a  and  74   a  of the suture  38   a  extend. The plunger  102  is enclosed by a tubular cylindrical housing  106 . The plunger  102  is pressed downward, relative to the housing  106  with a predetermined force, indicated by arrows  108  and  110  in FIG. 3. An annular transducer or load cell  114  provides an output indicative of the magnitude of the force  108  and  110  with which the suture retainer  92  is pressed against the bone  20   a  by the plunger  102 .  
         [0063]    While the sections  72   a  and  74   a  of the suture  38   a  are being tensioned with a predetermined force and while the plunger  102  is being pressed against the suture retainer  92  with a predetermined force, the suture retainer  92  is plastically deformed. To plastically deform the suture retainer  92 , a plurality of force applying or clamp members  120  and  122  are pressed against the suture retainer  92  with a predetermined minimum force, indicated schematically by arrows  126  in FIG. 3. The force application members  120  and  122  may have an arcuate configuration to conform to the spherical configuration of the suture retainer  92  or may have a flat configuration. The force applied against the suture retainer  92  by the force applying members  120  and  122  is sufficient to cause plastic deformation of the material of the suture retainer.  
         [0064]    The force  126  is applied against the suture retainer  92  while the suture retainer is at a temperature which is below the transition temperature of the biodegradable polymer which forms the suture retainer  92 . Thus, the suture retainer  92  is at approximately the same temperature as the bone  20   a  when the force  126  is applied against the suture retainer. The force  126  causes the material of the suture retainer  92  to flow and grip the sections  72   a  and  74   a  of the suture  38   a.    
         [0065]    Upon disengagement of the force application members  120  and  122  from the suture retainer  92 , the application of downward (as viewed in FIG. 3) force against the suture retainer  92  is interrupted. The upward tensioning of the sections  72   a  and  74   a  of the suture  38   a  is also interrupted. At this time, the plastically deformed suture retainer  92  securely grips the two sections  72   a  and  74   a  of the suture  38   a  to maintain the tension in the suture  38   a . If desired, a knot may be formed between the sections  72   a  and  74   a  of the suture as additional protection against the suture working loose over an extended period of time.  
         [0066]    The suture retainer  92  may be formed of many different materials. However, it is believed that it will be preferred to form the suture retainer  92  of a biodegradable polymer. One biodegradable polymer which may be utilized is polycaperlactone. Alternatively, the suture retainer  92  could be formed of polyethylene oxide terephthalate or polybutylene terephthalate. It is also contemplated that other biodegradable or bioerodible copolymers could be utilized.  
         [0067]    Although it is preferred to form the suture retainer  92  of a biodegradable material, the suture retainer could be formed of a material which is not biodegradable. For example, the suture retainer  92  could be formed of an acetyl resin, such as “DELRIN” (trademark). Alternatively, the suture retainer  92  could be formed of para-dimethylamino-benzenediazo sodium sulfonate, such as “DEXON” (trademark). The construction of the suture retainer  92  and the manner in which is cooperates with the suture  38   a  is the same as is disclosed in U.S. patent application Ser. No. 08/905,084 filed Aug. 1, 1997 by Peter M. Bonutti et al. and entitled “Method and Apparatus for Securing a Suture”.  
         [0068]    The suture retainer  92  is plastically deformed to grip the limbs  72   a  and  74   a  of the suture  38   a . However, the suture retainer  92  could be constructed so as to be mechanically actuated to grip the suture  38   a . If desired, a combination of a mechanical gripping action and plastic deformation could be utilized by a retainer to grip the suture  38   a.    
       Retaining Body Tissue Against Bone  
       [0069]    In the embodiment of the invention illustrated in FIG. 2, a bone suture assembly  32  is utilized to press surfaces  28  and  30  of a fracture  26  together. In the embodiment of the invention illustrated in FIG. 4, the suture anchor assembly is utilized to hold body tissue against movement relative to a bone. Since the embodiment of the invention illustrated in FIG. 4 is generally similar to the embodiments of the invention illustrated in FIGS. 2 and 3, similar numerals will be utilized in association with similar components, the suffix letter “b” being associated with the numerals of FIG. 4 to avoid confusion.  
         [0070]    A cylindrical passage  40   b  extends diametrically through a generally cylindrical bone  20   b . A bone suture assembly  32   b  is utilized to retain body tissue  132  against movement relative to the bone  20   b . The body tissue  132  may be a muscle, ligament, cartilage or other tissue which is to be held against movement relative to the bone  20   b.    
         [0071]    The bone suture assembly  32   b  includes a first suture anchor  50   b  and a second suture anchor  52   b . A suture  38   b  extends through the passage  40   b  and interconnects the suture anchors  50   b  and  52   b . Tension in the suture  38   b  presses the body tissue  132  against a side surface area on the bone  20   b . The suture  38   b  has sections or limbs  72   b  and  74   b  which extends through openings in the suture anchors  50   b  and  52   b  in the manner previously explained. A knot  78   b  interconnects the sections  72   b  and  74   b  of the suture  38   b  to press the suture anchor  52   b  firmly against the body tissue  132 . Although the illustrated suture has a pair of sections  72   b  and  74   b , the suture could have a single section if desired.  
         [0072]    The suture anchor assembly  32   b  is installed in association with the bone  20   b  and body tissue  132  in the same manner as previously explained in conjunction with the embodiment of the invention illustrated in FIG. 2. Thus, the passage  40  (FIG. 4) is formed in the bone  20   b  by drilling or other methods. The body tissue  132  may be offset to one side of the location where the passage  40   b  is formed during formation of the passage. This enables the passage  40   b  to be formed in the bone  20   b  without damaging the body tissue  132 .  
         [0073]    The suture anchor  50   b  is moved through the passage  40   b  with a longitudinal central axis of the suture anchor aligned with the longitudinal central axis of the passage  40   b . When the suture anchor  50   b  emerges from the passage  40   b , the anchor is pivoted to the orientation shown in FIG. 4. Alternatively, the anchor  50   b  may be mechanically expanded after emerging from the passage  40   b . A cylindrical tubular member may be used to line the passage  40   a  during movement of the anchor  50   b  through the passage in the manner previously described in connection with the embodiment of FIG. 2.  
         [0074]    After the anchor  50   b  has been moved to the position shown in FIG. 4, the body tissue  132  is positioned between the limbs  72   b  and  74   b  of the suture  38   b . The limbs  72   b  and  74   b  of the suture  38   b  are then inserted through the openings in the suture anchor  52   b . While a predetermined tension is maintained in the suture  38   b , the knot  78   b  is tied between the limbs  72   b  and  74   b  of the suture. This results in the body tissue  132  being pressed against the bone  20   b  with a predetermined force. A button or other force distributing member may be provided between the suture anchor  52   b  and body tissue  132  if desired.  
         [0075]    In the embodiment of the invention illustrated in FIG. 4, two suture anchors  50   b  and  52   b  are utilized to press the body tissue  132  against the bone  20   b . However, a suture retainer could be substituted for one or more of the suture anchors  50   b  or  52   b . For example, a suture retainer having the same construction and installed in the same manner as the suture retainer  92  of FIG. 3 could be substituted for the anchor  52   b  of FIG. 4. It should be understood that the suture retainer substituted for the anchor  52   b  of FIG. 4 could have any desired construction. Thus, a suture retainer having the construction of any one of the suture retainers disclosed in the aforementioned U.S. patent application Ser. No. 08/905,084 filed Aug. 1, 1997 by Peter M. Bonutti et al. and entitled “Method and Apparatus for Securing a Suture” could be utilized in place of the anchor  52   b  and/or the anchor  50   b.    
         [0076]    When a suture retainer is used in place of the anchor  52   b , the suture retainer applies force against the body tissue  132  to press the body tissue against the bone  20   b . If desired, a force distribution member could be provided between the suture retainer and the body tissue  132 .  
         [0077]    Although the passage  40   b  has been illustrated in FIG. 4 as having a linear configuration, the passage could have a nonlinear configuration if desired.  
         [0078]    In the embodiment of the invention illustrated in FIG. 4, body tissue  132  is disposed adjacent to only one side of the bone  20   b . However, if desired, body tissue could be disposed adjacent to opposite sides of the bone  20   b . The body tissue could be connected with the anchor  50   b  in many different ways. For example, a separate length of suture could be connected with the body tissue and anchor  50   b  or with the suture  38   b  adjacent to the anchor  50   b.    
         [0079]    An alternative manner of connecting body tissue with the side of the bone adjacent to the anchor  50   b  would be to insert the body tissue between the limbs  72   b  and  74   b  of the suture  36   b  in the same manner as shown with the anchor  52   b . If this is to be done, an end portion of the body tissue may be manually inserted between the limbs  72   b  and  74   b  of the suture  38   b.  If a central portion of the body tissue is to be disposed between the anchor  50   b  and the bone  20   b , the connector section  76   b  of the suture could be cut. One of the limbs  72   b  or  74   b  of the suture would then be separated from the anchor  50   b . The body tissue would be inserted between the limbs of the suture  38 . The separated end of the suture would then be inserted through the anchor  50   b  and connected with the other limb of the suture  38   b.    
         [0080]    In the embodiment of the invention illustrated in FIG. 4, the body tissue  132  is pressed against a bone  20   b  which has not been fractured. However, it is contemplated that the bone suture assembly  32  could be utilized to perform the dual functions of pressing body tissue against a bone and of pressing opposite side surfaces of a fracture together. This would result in the body tissue being pressed against the bone  20   b  in the manner illustrated in FIG. 4 and in opposite side surfaces of a fracture being pressed together in the manner illustrated in FIG. 2 for the opposite side surfaces  28  and  30  of the fracture  26 .  
       Nonlinear Suture Passage  
       [0081]    In the embodiment of the invention illustrated in FIG. 2, the passage  40  through which the suture  38  extends has a linear configuration. In the embodiment of the invention illustrated in FIG. 5, the passage through which the suture extends has a nonlinear configuration. Since the embodiment of the invention illustrated in FIG. 5 is generally similar to the embodiment of the invention illustrated in FIGS.  2 - 4 , similar numerals will be utilized to identify similar components, the suffix letter “c” being associated with the components of the embodiment of the invention illustrated in FIG. 5 to avoid confusion.  
         [0082]    A bone  20   c  as a fracture  26   c  which divides the bone into two sections  22   c  and  24   c . Opposite side surfaces  28   c  and  30   c  of the fracture  26   c  are pressed together by a bone suture assembly  32   c . The bone suture assembly  32   c  includes a suture  38   c  which extends between first and second suture anchors  50   c  and  52   c.    
         [0083]    In accordance with a feature of this embodiment of the invention, the suture  38   c  is disposed in a passage  40   c  having a nonlinear configuration. Thus, the passage  40   c  includes a first section  140  which is skewed relative to a second section  142  of the passage  40   c . A bend  144  is formed in the passage  40   c  at an intersection  146  of the first and second sections  140  and  142  of the passage  40   c . The flexible suture  38   c  extends around the bend  144  along a nonlinear path between the suture anchors  50   c  and  52   c . At the bend  144 , the suture  38   c  applies force against the section  24   c  of the bone  20   c  urging the section  24   c  toward the left (as viewed in FIG. 5). This force presses the sections  22   c  and  24   c  of the bone  20   c  firmly together at the fracture  26   c.    
         [0084]    The suture anchors  50   c  and  52   c  have the same cylindrical construction as the suture anchors  50  and  52  in the embodiment of the invention illustrated in FIG. 2. A knot  78   c  (FIG. 5) is provided between limbs of the suture  38   c  to maintain a desired tension in the suture  38   c . This tension pulls the suture anchors  50   c  and  52   c  toward each other. In addition, this tension presses the section  24   c  of the bone  20   c  firmly against the section  22   c  of the bone at the fracture  26   c.    
         [0085]    The first section  140  of the passage  40   c  is formed at an angle to and extends through a longitudinal central axis of the generally cylindrical bone  20   c . The second section  142  of the passage  40   c  is formed in a direction perpendicular, i.e., along a radius, of the generally cylindrical bone  20   c . The two sections  140  and  142  of the passage  40   c  terminate in the spongy cancellous bone tissue  44   c.    
         [0086]    When the suture assembly  32   c  is to be used to treat the fracture  26   c  in the bone  20   c , the two sections  22   c  and  24   c  of the bone are pressed together at the fracture  26   c  to align the side surfaces  28   c  and  30   c  of the fracture. A drill or other hole forming apparatus is then used to form the first section  140  of the passage  40   c . The drill or other hole forming apparatus is then used to form the second section  142  of the passage  40   c . When the second section  142  of the passage  40   c  intersects the first section  140  of the passage  40   c , formation of the section  142  of the passage  40   c  is interrupted.  
         [0087]    Once the nonlinear passage  40   c  has been formed in the two sections  22   c  and  24   c  of the bone  20   c , a tubular cylindrical liner (not shown) is inserted into the passage  40   c . The tubular cylindrical liner may be formed by two separate tubular members which are inserted at opposite ends of the passage  40   c . Alternatively, the tubular cylindrical liner may be formed by a single flexible tubular member which is inserted into the section  140  of the passage  40   c  and then moved around the bend  144  into the section  142  of the passage  40   c . It should be understood that the tubular cylindrical liner for the passage  40   c  could be omitted if desired.  
         [0088]    The cylindrical anchor  50   c , with the suture  38   c  connected thereto, is then positioned in axial alignment with the section  142  of the passage  40   c . The leading end  58   c  of the anchor  50   c  is then moved into the lined section  142  of the passage  40   c . A flexible pusher member applies force against the trailing end  60   c  of the anchor  50   c  and pushes the anchor around the bend  144  and through the section  140  of the passage  40   c.    
         [0089]    Alternatively, a flexible wire or other member could be inserted into the section  140  of the passage  40   c . The wire would move around the bend  144  and extend outward from the section  142  of the passage. The wire would then be connected with the anchor  50   c  and suture  38   c . The leading end  58   c  of the anchor  50   c  would then be inserted into the section  142  of the passage  40   c . Tension on the wire would pull the anchor  50   c  around the bend  144  and out of the section  140  of the passage  40   c.    
         [0090]    Once the anchor  50   c  has been moved out of the passage  40   c , the tubular liner for the passage may be withdrawn. If a one-piece tubular liner is used, it may be withdrawn from the open end of the section  142  of the passage  40   c . If a two-piece liner is used, one of the pieces may be withdrawn from the open end of the passage section  140  and slit to clear the suture  38   c . Alternatively, the slit could be formed in the piece of the liner before it is inserted into the passage section  140 . The other piece of the liner would be withdrawn from the open end of the passage section  142 . Alternatively, the tubular liner for the passage  40   c  may be left in place. Of course, the use of a tubular liner for the passage  40   c  may be omitted.  
         [0091]    The suture  38   c  is then threaded through openings in the suture anchor  52   c . The suture  38   c  is then tensioned and the second anchor  52   c  is pressed against the outer side surface of the bone  20   c . While a predetermined tension force is maintained in the suture  38   c , the knot  78   c  is tied.  
         [0092]    In the illustrated embodiment of the invention, the two sections  140  and  142  of the passage  40   c  have a straight cylindrical configuration. However, it is contemplated that the sections  140  and  142  of the passage  40   c  could have a different configuration if desired. For example, the section  140  and/or  142  of the passage  40   c  could have a nonlinear central axis and could have a noncircular cross-sectional configuration of desired.  
         [0093]    Body tissue, corresponding to the body tissue  132  of FIG. 4 could be disposed between the anchor  50   c  and/or  52   c  and the bone  20   c . Although the suture  38   c  has been illustrated as having a pair of limbs or sections which extend between the anchors  50   c  and  52   c , the suture  38   c  could have a single limb or section if desired. The anchor  50   c  could mechanically expand, by absorbing body liquid or under the influence of expansion springs, after the anchor has emerged from the passage  40   c  to prevent the anchor from being pulled back through the passage.  
       NONLINEAR PASSAGE—SECOND EMBODIMENT  
       [0094]    In the embodiment of the invention illustrated in FIG. 5, the bone suture assembly  32   c  associated with the nonlinear passage  40   c  includes a pair of suture anchors  50   c  and  52   c . In the embodiment of the invention illustrated in FIG. 6, a suture retainer in substituted for one of the suture anchors in much the same manner as previously described in conjunction with the embodiment of the invention illustrated in FIG. 3. Since the embodiment of the invention illustrated in FIG. 6 is generally similar to the embodiment of the invention illustrated in FIGS.  2 - 5 , similar numerals will be utilized to designate similar components, the suffix letter “d” being associated with the numerals of FIG. 6 in order to avoid confusion.  
         [0095]    A bone  20   d  has a fracture  26   d  which divides the bone into two sections  22   d  and  24   d . The fracture  26   d  has side surfaces  28   d  and  30   d  which are pressed together by a bone suture assembly  32   d . The bone suture assembly  32   d  includes a suture  38   d  which extends through a nonlinear passage  40   d  having the same construction as the nonlinear passage  40   c  of FIG. 5.  
         [0096]    In accordance with a feature of this embodiment of the invention, the bone suture assembly  32   d  includes a suture anchor  50   d  having the same construction as the suture anchor  50  of FIG. 2, and a suture retainer  92   d  having the same construction as the suture retainer  92  of FIG. 3. The suture anchor  50   d  and suture retainer  92   d  maintain a predetermined tension in the suture  38   d . This results in the suture anchor  50   d  being firmly pressed against the section  24   d  of the bone  20   d . The suture retainer  92   d  is firmly pressed against the section  22   d  of the bone  20   d  by the tension in the suture  38   d.    
         [0097]    Since the passage  40   d  has a nonlinear configuration, the suture  38   d  is effective to apply a force component to the section  24   d  of the bone  20   d  urging the section  24   d  of the bone toward the left (as viewed in FIG. 6). This results in the surface  30   d  of the fracture  26   d  being pressed firmly against the surface  28   d  of the fracture.  
         [0098]    The suture retainer  92   d  is plastically deformed to grip the suture  38   d  in the same manner as previously described herein in conjunction with the suture retainer  92  of FIG. 3. However, the suture retainer  92   d  could be constructed so as to form a mechanical connection with the suture  38   d . If desired, a suture retainer could be substituted for the anchor  50   d.    
         [0099]    Although both the suture retainer  92   d  and anchor  50   d  have been illustrated in FIG. 6 as being disposed in engagement with the bone  20   d , a force distributing member could be provided between the anchor and/or suture retainer and the bone. It is contemplated that body tissue, similar to the body tissue  132  of FIG. 4, could be disposed between the anchor  50   d  and/or the suture retainer  92   d  and the bone  20   d.    
       Tissue Tensioning with Bone Fragment Retaining  
       [0100]    In the embodiment of the invention illustrated in FIG. 2, the fracture in a portion of a bone is treated. In the embodiment of the invention illustrated in FIGS. 7 and 8, a fracture results in a fragment of a bone being separated from a main portion of the bone. The bone fragment is connected with the main portion of the bone by muscle, tendon, ligament, cartilage or other fibrous body tissue. In the embodiment of the invention illustrated in FIGS. 7 and 8, the fibrous body tissue is tensioned as the bone fragment is positioned relative to the main portion of the bone. Since the embodiment of the invention illustrated in FIGS. 7 and 8 is generally similar to the embodiment of the invention illustrated in FIGS.  2 - 6 , similar numerals will be utilized to designate similar components, the suffix “e” being associated with the numerals of FIGS. 7 and 8 in order to avoid confusion.  
         [0101]    A bone fragment  154  is separate from a main bone  20   e  (FIG. 7). The fragment  154  is connected with the main bone  20   e  by fibrous body tissue  158 , i.e., muscle, tendon, ligament, cartilage, etc. The fibrous body tissue  158  extends between the bone fragment  154  and a portion  160  of the main bone  20   e . The bone fragment  154  has a side surface  28   e  with a configuration which matches the configuration of a side surface  30   e  of a fracture  26   e  which occurred in the main bone  20   e.    
         [0102]    In order to promote healing of the main bone  20   e , a bone suture assembly  32   e  (FIG. 8) is utilized to pull the bone fragment  154  toward the main bone  20   e . As this occurs, the fibrous body tissue  158  is tensioned and the side surface  28   e  on the bone fragment  154  is pressed against the side surface  30   e  on the main bone  20   e . The bone fragment  154  is pressed firmly against the main bone  20   e  by the bone suture assembly  32   e . Thus, the gap illustrated schematically in FIG. 8, between the side surfaces  28   e  and  30   e  of the fracture  26   e , is eliminated and the side surfaces of the fracture are pressed firmly together by the bone suture assembly  32   e . If desired, the bone fragment  154  may be manually pressed against the main bone  20   e  before the bone suture assembly is pulled tight.  
         [0103]    The bone suture assembly  32   e  includes a suture  38   e  having limbs or sections  72   e  and  74   e . The suture  38   e  extends through openings in a first suture anchor  50   e . The suture then extends into a passage  40   e  formed in the bone fragment  154  and the main bone  20   e.    
         [0104]    The passage  40   e  includes a first section  140   e  which extends through the bone fragment  154 . In addition, the passage  40   e  includes a second section  142   e  which extend through the main bone  20   e . The limbs or section  72   e  and  74   e  of the suture  38   e  extends through a second anchor  52   e.    
         [0105]    During installation of the bone suture assembly  32   e , the limbs  72   e  and  74   e  of the suture  38   e  are gripped by a force or tension measurement device  98   e . The tension measurement device  98   e  includes a load cell which measures the amount of tension applied to the limbs  72   e  and  74   e  of the suture  38   e.    
         [0106]    As tension is applied to the limbs  72   e  and  74   e  of the suture  38   e , the bone fragment  154  is pulled toward the right (as viewed in FIG. 8) to move the side surface  28   e  on the bone fragment into alignment with the side surface  30   e  on the main bone  20   e . As this occurs, the fibrous body tissue  158  is stretched or tensioned. While a predetermined force is transmitted through the limbs  72   e  and  74   e  to the suture anchor  50   e  and the bone fragment  154  to firmly press the bone fragment against the main bone  20   e , a knot  78   e  is tied to interconnect the limbs  72   e  and  74   e . While the predetermined tension is maintained and the knot  78   e  tied, the second anchor  52   e  is firmly pressed against the side surface of the main bone  20   e.    
         [0107]    Although the passage  40   e  could have a linear configuration if desired, in the embodiment of the invention illustrated in FIG. 8, the passage  40   e  has a nonlinear configuration. Thus, the first section  140   e  of the passage  40   e  has a central axis which is skewed relative to a central axis of the second section  142   e  of the passage  40   e . This enables the flexible suture  38   e  to apply force to the bone fragment  154  having components urging the bone fragment rightward (as viewed in FIG. 8) against the surface  30   e  on the main bone  20   e  and downward (as viewed in FIG. 8) to maintain the tension in the fibrous body tissue  158 .  
         [0108]    When the passage  40   e  is to be formed in the bone fragment  154  and main bone section  20   e , a hole is drilled through the bone fragment  154  to form the first section  140   e  of the passage. The second portion  142   e  of the passage  40   e  is drilled in the main bone  20   e . It should be understood that the passage  40   e  could be formed in many different ways other than drilling. For example, a cutting tool or laser could be used to form the passage  40   e.    
         [0109]    The second section  142   e  of the passage  40   e  has a longitudinal central axis which is skewed at an acute angle relative to the longitudinal central axis of the first section  140   e  of the passage in the bone fragment  154 . Thus, the first portion  140   e  of the passage  40   e  in the bone fragment  154  has a central axis which is close to being perpendicular to a longitudinal central axis of the main bone  20   e . The second portion  142   e  of the passage  40   e  has a longitudinal central axis which is angularly offset to a substantial arc relative to the longitudinal central axis of the main bone  20   e.    
         [0110]    The anchor  50   e  is moved through the first section  140   e  of the passage  40   e  and positioned in engagement with an outer side surface of the bone fragment. The free ends of the limbs  72   e  and  74   e  of the suture  38   e  are then moved rightward (as viewed in FIG. 8) through the second portion  142   e  of the passage  40   e . The free ends of the suture  38   e  are then threaded through openings in the second anchor  52   e.    
         [0111]    After the suture  38   e  has been inserted through openings in the second anchor  52   e , the force or tension measuring device  98   e  is utilized to pull the free ends of the suture  38   e  toward the right (as viewed in FIG. 8). This tension pulls the bone fragment  154  into engagement with the main bone  20   e . The knot  78   e  is tied in the free ends of the suture  38   e  while the tension is maintained in the suture.  
         [0112]    If desired, the bone suture assembly  32   e  could be positioned relative to the bone  20   e  and the bone fragment  154  by moving the anchor  50   e  first through the second section  142   e  of the passage disposed in the main bone  20   e  and then through the first section  140   e  of the passage disposed in the fragment  154 . The free ends of the suture would then be inserted through the second anchor  52   e . The suture  38   e  would be tensioned to pull the bone fragment  154  into place with the side surface  28   e  in aligned engagement with the surface  30   e  on the main bone  20   e . The knot  78   e  would then be tied while maintaining the desired tension in the suture  38   e.    
         [0113]    It should be understood that the anchor  52   e  and knot  78   e  could be positioned adjacent to the bone fragment  154  and the anchor  50   e  positioned adjacent to the bone  20   e . Although only a single bone suture assembly  32   e  has been illustrated in FIG. 8, multiple bone suture assemblies could be used to position the bone fragment  154  relative to the bone  20   e.    
         [0114]    In the embodiment of the invention illustrated in FIGS. 7 and 8, the bone suture assembly  32   e  includes a pair of anchors  50   e  and  52   e . If desired, a suture retainer could be substituted for either or both of the anchors  50   e  and  52   e . Thus, a suture retainer having a construction similar to the construction of the suture retainer  92  of FIG. 3 could be used in place of the second anchor  52   e . It should be understood that the suture retainer  92  could have the same construction as any one of the suture retainers disclosed in the aforementioned U.S. patent application Ser. No. 08/905,084 filed Aug. 1, 1997 by Peter M. Bonutti et al. and entitled “Method and Apparatus for Securing a Suture”.  
         [0115]    In the embodiment of the invention illustrated in FIG. 8, the anchors  50   e  and  52   e  are placed in engagement with the bone of fragment  154  and main bone  20   e . However, it is contemplated that the anchor  50   e  and/or  52   e  could be positioned in engagement with body tissue other than bone. For example, the anchor  50   e  could be positioned in engagement with a portion of the fibrous body tissue  158  to position the fibrous body tissue  158  relative to the bone fragment  154  and to more securely interconnect the fibrous body tissue and the bone fragment. If desired, body tissue could be positioned between the anchor  52   e  and the main bone  20   e.    
         [0116]    In FIG. 8, there is a single bone fragment  154 . However, fractures may occur in such a manner as to have a plurality of bone fragments. A plurality of bone suture assemblies  32   e  could be utilized to interconnect the plurality of bone fragments and the main bone.  
         [0117]    When a fracture occurs in such a manner as to form a plurality of bone fragments, it may be desired to use bone suture assemblies  32   e  in association with only the larger bone fragments. If desired, a bridge or cover member could extend across the bone fragments to position the bone fragments relative to each other. One or more bone suture assemblies  32   e  would extend through one or more of the larger bone fragments and through the bridge or cover member. Force applied against the bridge or cover member by an anchor or anchors in a bone suture assembly or assemblies  32   e  would urge the bridge or cover member toward the main bone  20   e  to position the smaller bone fragments relative to the larger bone fragments and main bone  20   e  and to press the bone fragments against each other and against the main bone.  
         [0118]    One or more of the anchors  50   e  and  52   e  could be formed of body tissue or of material which absorbs body fluid and expands. Alternatively, one or more of the anchors  50   e  or  52   e  could be mechanically expanded to block movement into the passage  50   e.    
       Bone Fragment Retention  
       [0119]    In the embodiment of the invention illustrated in FIG. 2, the bone suture assembly  32  extends between diametrically opposite outer side surface areas on the bone  20 . This results in the first suture anchor  50  being disposed against an outer side surface of the hard outer layer  42  of the bone  20  (FIG. 1) and the suture anchor  52  being disposed against the outer side surface of the hard outer layer  42  on the opposite side of the bone. In the embodiment of the invention illustrated in FIG. 9, one of the anchors is disposed within the bone and the other anchor is disposed outside of the bone. Since the embodiment of the invention illustrated in FIG. 9 is generally similar to the embodiment of the invention illustrated in FIGS.  2 - 8 , similar numerals will be utilized to identify similar components, the suffix letter “f” being associated with the numerals of FIG. 9 in order to avoid confusion.  
         [0120]    A bone  20   f  has a hard outer layer  42   f  which encloses spongy cancellous bone tissue  44   f . A fragment  164  has broken away from the hard outer layer  42   f . A bone suture assembly  32   f  is used to position and hold the fragment  164  in engagement with the bone  20   f . The bone suture assembly  32   f  includes a first suture anchor  50   f  which is disposed in engagement with an inner side surface  166  of the outer layer  42   f  of bone. A second anchor  50   f  is disposed in engagement with an outer side surface  168  of the fragment  164 . A suture  38   f  extends between the first and second anchors  50  and  52   f . The suture  38   f  extends through a passage  40   f  which extends across a fracture  26   f.    
         [0121]    When the bone suture assembly  32   f  is used to position the fragment  164  against the outer layer  42   f  of the bone  20   f , the fragment  164  is aligned with the outer layer  42   f  of the bone  20   f . At this time, a side surface  172  on the fragment  164  is disposed in aligned engagement with a side surface  174  on the bone  20   f . The two side surfaces  172  and  174  were formed by breaking away of the fragment  164  from the outer layer  42   f  of the bone.  
         [0122]    Once the fragment  164  has been aligned with the bone  20   f , the linear passage  40   f  is formed by drilling or other methods through the fragment  164  and the outer layer  42   f  of bone. A cylindrical tubular member (not shown) having a thin cylindrical side wall is then inserted through the passage  40   f . The first anchor  50   f  is moved to an orientation in which a longitudinal central axis of the first anchor is aligned with a longitudinal central axis of the cylindrical tubular member.  
         [0123]    The first anchor  50   f  is then moved through the cylindrical tubular member, across the fracture  26   f  and into the spongy cancellous bone tissue  44 . A pusher member applies force against a trailing end of a first anchor  50   f  to push the anchor through the tubular member. When the leading end of the first anchor  50   f  emerges from the passage  40   f , the longitudinal central axis of the first anchor is aligned with the longitudinal central axis of the passage  40   f.    
         [0124]    The first anchor  50   f  is then pivoted through 90 degrees to change its orientation to the orientation shown in FIG. 9. The tubular member is then withdrawn from the passage  40   f . The free ends of the suture  38   f  are then inserted through openings in the anchor  52   f . The suture is tensioned to press the anchor  50   f  against the inner side surface  166  on the outer layer  42   f  of the bone  20   f . The second anchor  52   f  is pressed against the outer side surface  168  or the fragment  164  with a predetermined force by the tension in the suture  38   f . A knot  78   f  is then tied in the free ends of the suture  38   f  to maintain the desired tension in the suture.  
         [0125]    Although it is believed that it may be desired to remove the tubular member from the passage  40   f , the tubular member could be left in the passage if desired. If the tubular member is to be left in the passage  40   f , the tubular member may be formed of a biodegradable or bioerodible copolymer. Of course, the use of the tubular member could be eliminated if desired.  
         [0126]    It should be understood that a suture retainer, having a construction similar to the construction of the suture retainer  92  of FIG. 3, could be used in place of the second anchor  52   f  if desired. Although the suture anchor  52   f  has been shown in FIG. 9 as being disposed in direct abutting engagement with the outer side surface  168  of the bone fragment  164 , a layer of body tissue could be provided between the suture anchor  52   f  and the outer side surface  168  of the bone fragment  164  to hold the body tissue against movement relative to the bone  20   f . If desired, a plurality of bone suture assemblies  32   f  could be utilized to hold the bone fragment  164 .  
       Use of Plates with Bone Suture Assembly  
       [0127]    In the embodiment of the invention illustrated in FIG. 2, the suture anchors  50  and  52  are disposed in abutting engagement with an outer side surface of a bone. In the embodiment of the invention illustrated in FIG. 10, a pair of bone plates and rigid fasteners are used in association with a bone suture assembly. Since the embodiment of the invention illustrated in FIG. 10 is generally similar to the embodiment of the invention illustrated in FIGS.  2 - 9 , similar numerals will be utilized to designated similar components, the suffix “g” being associated with the numerals of FIG. 10 to avoid confusion.  
         [0128]    A bone  20   g  has sections  22   g  and  24   g  which are separated by a fracture  26   g . In accordance with a feature of this embodiment of the invention, a pair of plate members  184  and  186  are used in association with a bone suture assembly  32   g . The plate members  184  and  186  may be formed of any desired biocompatible material. Thus, the plate members may be formed of metal or a polymeric material. If the plate members  184  and  186  are formed of polymeric material, biodegradable or bioerodible copolymers could be utilized.  
         [0129]    In the illustrated embodiment of the invention, the plate members  184  and  186  are rigid and are shaped to engage the bone  20   g . If desired, the plate members  184  and  186  could have sufficient flexibility to enable the plate members to be plastically deformed to the configuration of the bone  20   g  after having been positioned in engagement with the bone.  
         [0130]    A first suture anchor  50   g  is pressed against the plate member  184  by tension in a suture  38   g . The suture  38   g  extends through a passage  40   g  in the bone  20   g . A second anchor  52   g  is pressed against the plate member  186  by the tension in the suture  38   g . A knot  78   g  is provided in the suture  38   g.    
         [0131]    A pair of screws  190  and  192  extend diametrically through the bone  20   g  between the plate members  184  and  186 . The screws  190  and  192  are engaged by nuts  196  and  198  which engage the plate member  184 . The screws  190  and  192  and nuts  196  and  198  cooperate to press the plate members  184  and  186  against the bone  20   g . If desired, bone suture assemblies having the same construction as the bone suture assembly  32   g  could be substituted for the screws  190  and  192  and nuts  196  and  198  so that the plates  184  and  186  would be held in position against the bone  20   g  by only the plurality of bone suture assemblies  32   g.    
         [0132]    The screws  190  and  192  and nuts  196  and  198  may be formed of any desired biocompatible material. Thus, the screws  190  and  192  and nuts  196  and  198  may be formed of metal or a polymeric material. If the screws  190  and  192  and nuts  196  and  198  are formed of polymeric material, biodegradable or bioerodible copolymers could be utilized.  
         [0133]    In the illustrated embodiment of the invention, the screws  190  and  192  extend through the bone  20   g . It is contemplated that shorter screws could be utilized if desired. These shorter screws would have relatively coarse bone engaging thread convolutions to hold the short screws and plate members  184  and  186  in place. The shorter screws would have a length which is less than diameter of the bone  20   g.    
         [0134]    In the illustrated embodiment of the invention, the bone suture assembly  32   g  extends through a linear passage  40   g . If desired, the passage  40   g  could have a nonlinear configuration. If bone suture assemblies  32   g  are substituted for the screws  190  and  192  and nuts  196  and  198 , some of the bone suture assemblies could extend through linear passages while other bone suture assemblies extend through nonlinear passages.  
       Installation Method  
       [0135]    In the embodiment of the invention illustrated in FIG. 2, the passage  40  is formed in the bone  20  by any desired method. A thin walled cylindrical tubular member is then inserted into the passage and the first suture anchor  50  moved through the thin walled member. In the embodiment of the invention illustrated in FIGS. 11 and 12, a cannulated drill is used to drill a passage through a bone and to guide movement of the first anchor through the bone. Since the embodiment of the invention illustrated in FIGS. 11 and 12 is generally similar to the embodiments of the invention illustrated in FIGS.  2 - 10 , similar numerals will be utilized to identify similar components, the suffix “h” being associated with the numerals in FIGS. 11 and 12 to avoid confusion.  
         [0136]    A bone  20   h  has a fracture (not shown). When the fracture is to be treated with a bone suture assembly  32   h  (FIG. 12), a thin elongated cylindrical member or K-wire  204  is first inserted through the bone  20   h . This may be done by rotating the thin elongated member  204  with a drill drive mechanism in the manner indicated by an arrow  206  in FIG. 11. The drill drive mechanism is provided with a passage which extends through a drive shaft for the mechanism. While the thin elongated member  204  is being rotated by the drill drive mechanism, the K-wire extends through the passage in the drill drive mechanism.  
         [0137]    As the thin elongated member  204  is rotated by the drill drive mechanism, it is pressed against the bone  20   h . As the thin elongated member  204  is rotated, in the manner indicated by the arrow  206  in FIG. 11, the thin elongated member is moved diametrically through the generally cylindrical bone  20   h  until the leading end of the thin elongated member  204  extends from the opposite side of the bone. Thus, the thin elongated member  204  is moved through the hard outer layer  42   h  (FIG. 12) at one side of the bone  20   h , through the spongy or cancellous bone tissue  44   h , and through the hard outer layer at the diametrically opposite side of the bone. When this has been done, the thin elongated member  204  will extend across the fracture in the bone.  
         [0138]    The drill drive mechanism is then disengaged from the thin elongated member  204 . A cannulated drill  210  is moved axially along the thin elongated member until the leading end portion  212  of the drill  210  engages the bone  20   h  (FIG. 11). The drill  210  is then gripped by the drill drive mechanism.  
         [0139]    While the thin elongated member  204  remains stationary, the drill  210  is rotated about the thin elongated member in the manner indicated by an arrow  214  in FIG. 11. As the drill  210  is rotated about the stationary thin elongated member  204 , the drill is moved axially into the bone  20   h . As this occurs, the leading end  212  of the drill enlarges the hole or passage formed in the bone  20   h  by the thin elongated member  204 . The drill  210  is moved along the thin elongated member  204  until the drill extends diametrically across the bone  20   h . This movement of the drill  210  is guided by engagement of the thin elongated member  204  with a side wall of a cylindrical passage  218  which extends axially through the drill  210 . Movement of the drill  210  through the bone  20   h  forms a passage  40   h  which extends through a fracture in the bone.  
         [0140]    Once the drill  210  has been moved diametrically through the generally cylindrical bone  20   h  (FIG. 12), the thin elongated member  204  is withdrawn from the drill. This leaves an open cylindrical passage  218  extending through the drill  210  and across the bone  20   h . The passage  218  has a diameter which is just slightly greater than the diameter of a cylindrical first anchor  50   h  of the bone suture assembly  32   h . The cylindrical first anchor  50   h  is axially aligned with the passage  218  in the drill  210 , in the manner shown in FIG. 12. At this time, the suture  38   h  has been inserted through openings in the first anchor  50   h  and suture limbs or sections  72   h  and  74   h  extend away from the first anchor  50   h , in the manner indicated schematically in FIG. 12.  
         [0141]    A cylindrical pusher member  222  is axially aligned with the first anchor  50   h  and the passage  218  through the drill  210 . The pusher member  222  is utilized to push the first anchor  50   h  through the drill  210  to the far side of the bone  20   h.    
         [0142]    As the first suture anchor  50   h  emerges from the passage  28  in the drill  210 , the anchor is pivoted through ninety degrees. This pivotal movement changes the orientation of the anchor  50   h  from an orientation in which the longitudinal central axis of the anchor  50   h  is aligned with the longitudinal central axis of the passage  218  and drill  210  to an orientation in which a longitudinal central axis of the cylindrical anchor  50   h  extends perpendicular to the longitudinal central axis of the passage and drill. The manner in which the anchor  50   h  is pivoted is the same as is described in the aforementioned U.S. Pat. Nos. 5,527,343 and 5,534,012.  
         [0143]    The pusher member  222  is then withdrawn from the drill  10  and the drill is withdrawn from the passage formed through the bone  20   h . As this occurs, the suture  38   h  is tensioned to hold the anchor  50   h  in place against the bone  20   h . The drill  210  is then disengaged from the suture  38   h . The free limbs  72  and  74  of the suture  38   h  are then inserted through a second anchor corresponding to the anchor  52  in FIG. 2. While a predetermined tension is maintained in the suture  38   h , the suture is tied to hold the second suture anchor, corresponding to the suture anchor  52  in FIG. 2, against the bone  20   h  on a side of the bone opposite from the anchor  50   h.    
         [0144]    In the foregoing description, the drill  210  has been a rigid drill which has been used to form a linear passage to the bone  20   h . However, it is contemplated that a flexible drill could be utilized to drill a passage through the bone. If this was done, the drill could be guided in such a manner as to form a nonlinear passage in the bone.  
         [0145]    The foregoing description of how the passage  40   h  is formed has been in conjunction with a bone  20   h  having a fracture similar to the fracture  26  of FIG. 2. However, it is contemplated that the thin elongated member  204  and drill  210  could be used to form a passage in a bone which has not been fractured (FIG. 4). The thin elongated member  204  and  210  could be used to form a passage which extends only part way through a bone (FIG. 9).  
         [0146]    In the description of the embodiments of the invention illustrated in FIGS.  1 - 12 , the suture  38  (FIG. 2) has a pair of limbs or sections  72  and  74 . It is contemplated that the suture  38  could have only a single limb which would be connected at one end with the first anchor  50  and at the opposite end with the second anchor  52 . This single limb could either be tied off at the second anchor  52  or gripped by a suture retainer, similar to the suture retainer  92  of FIG. 3.  
         [0147]    In the embodiments of the invention illustrated in FIGS.  1 - 12 , the suture  38  has been formed separately from the first suture anchor  50 . It is contemplated that the first suture anchor  50  could be formed as one piece with the suture  38 . For example, the suture and anchor could be formed as one piece in a manner similar to that disclosed in U.S. Pat. No. 4,669,473 or in U.S. Pat. No. 4,741,330.  
         [0148]    The anchors  50  and  52  in the embodiment of FIGS.  2 - 12  could have any one of many different constructions. For example, the anchors could expand by absorbing body fluid. The anchor  50 , which is moved through a passage  40  in the embodiments of FIGS.  2 - 12 , could mechanically expand upon exiting from the passage.  
       Positioning of Tubular Member  
       [0149]    In the embodiment of the invention illustrated in FIG. 13, a tubular member is positioned in the passage which extends through the bone. Since the embodiment of the invention illustrated in FIG. 13 is generally similar to the embodiments of the invention illustrated in FIGS.  1 - 12 , similar numerals will be utilized to designate similar components, the suffix letter “j” being associated with the numerals of FIG. 13 to avoid confusion.  
         [0150]    A bone  20   j  which has been fractured is illustrated in FIG. 1. The bone  20   j  is divided into two sections  22   j  and  24   j  by a fracture  26   j . Opposite side surfaces  28   j  and  30   j  of the fracture  26   j  are pressed together by bone securing assemblies  32   j.    
         [0151]    It should be understood that the bone securing assemblies  32   j  may be utilized in the treatment of any one of many different types of fractures. The fractures may or may not result in the formation of one or more bone fragments. In FIG. 13, the bone securing assembly  32   j  has been illustrated as interconnecting sections  22   j  and  24   j  of a complete bone fracture of the spiral type. However, the bone securing assemblies  32   j  could be utilized to connect a fragment of a bone to the main portion of the bone from which the fragment was broken off.  
         [0152]    The bone securing assembly  32   j  (FIG. 13) includes a force transmitting member  38   j  which extends across the fracture  26   j . The force transmitting member  38   j  may be any one of many different types of force transmitting members. The force transmitting member  38   j  may be formed of human or animal body tissue. However, it is presently preferred to use a suture as the force transmitting member  38   j . Therefore, the force transmitting member  38   j  will be referred to herein as a suture.  
         [0153]    The suture  38   j , that is, the force transmitting member, is disposed in a straight cylindrical passage  40   j  which extends diametrically across a generally cylindrical portion of the bone  20   j . The passage  40   j  extends through hard compact tissue of an outer layer  42   j  of the bone and through spongy or cancellous bone tissue  44   j  which is enclosed by the hard outer layer. Although the passage  40   j  has a linear configuration, the passage could have a nonlinear configuration if desired.  
         [0154]    The suture  38   j  extends between a first suture anchor  50   j  disposed on one side of the fracture  26   j  and a second suture anchor  52   j  disposed on the opposite side of the fracture. Tension is maintained in the suture  38   j  to press the suture anchors  50   j  and  52   j  against opposite sides of the bone  201  with a predetermined force. This force presses the side surfaces  28   j  and  30   j  of the fracture  26   j  firmly together to promote healing of the fracture. If desired, buttons or other force distributing members could be provided between the anchors  50   j  and  52   j  and the bone  20   j . Body tissue could be disposed between the anchors  50   j  and  52   j  and the bone  20   j.    
         [0155]    The suture  38   j  and/or suture anchors  50   j  and  52   j  may be formed of any desired natural or artificial material. For example, the suture  38   j  may be formed of either a polymeric material or a metal. The suture  38   j  may be biodegradable. Any known suture material may be utilized to form the suture  38   j.    
         [0156]    The suture anchors  50   j  and  52   j  have the same construction. However, the anchor  50   j  could have a construction which is different than the construction of the anchor  52   j . The anchor  50   j  has a cylindrical outer side surface  56   j  which extends between smooth rounded end portions  581  and  60   j . A pair of parallel cylindrical openings  64   j  and  66   j  extend diametrically through the anchor  50   j . The anchor  50   j  is free of sharp corners or projections to avoid cutting or abrading of body tissue disposed adjacent to the anchor.  
         [0157]    The suture anchor  50   j  is made of a biocompatible material. Suitable materials include stainless steel or titanium, cobalt chrome and other biocompatible metals. Polymeric material may also be used, suitable polymeric materials includes polyethylene, polypropylene, and biodegradable material such as PLA and PGA. It is believed that it may be preferred to form the suture anchors  50   j  and  52   j  from biodegradable or bioerodible copolymers. If desired, the anchor  50   j  could be formed of body material or hydrophilic materials.  
         [0158]    It is contemplated that the anchor  50   j  may have any desired configuration. For example, the anchor  50   j  could have any one of the configurations disclosed in U.S. Pat. No. 5,522,846 issued Jun. 4, 1996 and entitled “Suture Anchor”. Alternatively, the suture anchor  50   j  could have the configuration disclosed in U.S. Pat. No. 5,534,012 issued Jul. 9, 1996 and entitled “Method and Apparatus for Anchoring a Suture”.  
         [0159]    The cross-sectional size of the anchor  50   j  may be such as to enable the anchor to be moved through the passage  40   j . However, the anchor  50   j  could have a size and configuration which would prevent movement of the anchor  50   j  through the passage  40   j . For example, the anchors  50   j  and  52   j  could have the same construction as the retainer  92  of FIG. 3.  
         [0160]    The length of the anchor  50   j  is such as to enable it to span an opening at an end of the passage  40   j  and transmit force from the suture  38   j  to a substantial area on the outer layer  42   j  of the bone  20   j . The length of the anchor  50   j  may be approximately three times the diameter of the anchor. It is believed that it will be preferred to form the anchor  50   j  in such a manner as to eliminate any sharp corners or projections.  
         [0161]    In the illustrated embodiment of the invention, the anchor  50   j  has a cylindrical configuration. This particular anchor has an axial length of about two millimeters and a diameter of about one millimeter. The openings  64   j  and  66   j  have a diameter of about one-half millimeter.  
         [0162]    It should be understood that the foregoing dimensions have been set forth herein for purposes of clarity of description and it is contemplated that the size of the anchor  50   j  may vary as a function of the size of the bone being treated. Thus, relatively small anchors may be used in association with treatment of small bones in a wrist, hand, foot or ankle of a patient. Relatively large anchors may be used in association with treatment of larger bones in an arm, shoulder, leg or hip of a patient. It should be understood that the bone securing assembly  32   j  may be used in conjunction with many different bones other than the specific bones previously mentioned.  
         [0163]    Only a single anchor  50   j  or  52   j  has been shown at opposite ends of the passage  40   j . It is contemplated that a plurality of anchors could be provided at each end of the passage  40   j . For example, a pair of separate or interconnected anchors could be provided in a manner similar to that disclosed in the aforementioned U.S. Pat. No. 5,534,012.  
         [0164]    In the embodiment of the invention illustrated in FIG. 13, the suture  38   j  has a pair of limbs or sections  72   j  and  74   j  which extend through the openings  64   j  and  66   j  in the suture anchors  50   j  and  52   j . A connector section  76   j  interconnects the two limbs  72   j  and  74   j  of the suture  38   j  and engages a portion of the anchor  50   j . A knot  78   j  is formed in the opposite ends of the limbs  72   j  and  74   j  to interconnect the two limbs of the suture  38   j.    
         [0165]    When the knot  78   j  is formed, a predetermined tension is present in the limbs  72   j  and  74   j  of the suture  38   j . This results in the suture anchors  50   j  and  52   j  being pressed firmly against the bone  20   j  with a predetermined force. This predetermined force is maintained during and after tying of the knot  78   j.    
         [0166]    When the bone securing assembly  32   j  is to be used to treat the fracture  26   j  in the bone  20   j , the two sections  22   j  and  24   j  of the bone are pressed together at the fracture  26   j  to align the side surfaces  28   j  and  30   j  of the fracture. A drill is then used to form the passage  40   j  which extends diametrically through the generally cylindrical bone  20   j . Of course, the passage  40   j  could be formed by the use of a tool other than a drill. If desired, the passage  40   j  could have a noncircular cross-sectional configuration.  
         [0167]    Once the passage  40   j  has been formed in the two sections  22   j  and  24   j  of the bone  20   j , a tubular cylindrical member  240  is inserted into the passage  40   j  and extends diametrically through the bone  20   j . The leading end  242  of the tubular cylindrical member  240  is aligned with a circular outlet  84   j  from the passage  40   j . The opposite or trailing end  244  of the tubular member is aligned with a circular inlet  86   j  to the passage  40   j . The tubular member  240  has a thin cylindrical wall which engages the sections  22   j  and  24   j  of the bone  201 . A cylindrical inner side surface of the tubular member  240  defines a cylindrical passage having a diameter which is only slightly less than the diameter of the passage  40   j.    
         [0168]    The leading end  242  of the tubular member  240  is disposed in the compact outer layer  42   j  of the bone  20   j . Similarly, the trailing end  244  of the tubular member  240  is disposed in the compact outer layer  42   j  of the bone  20   j . The tubular member  240  extends across the fracture  26   j  and stabilizes the two sections  22   j  and  24   j  of the bone  20   j . Since the opposite end portions of the tubular member  240  are disposed in the compact outer layer  42   j  of the bone  20   j , the tubular member is solidly supported and holds the two sections  22   j  and  24   j  of the bone  20   j  in alignment at the fracture  26   j.    
         [0169]    The opposite ends  242  and  244  of the tubular member  240  are axially spaced from a generally cylindrical outer side surface  250  on the bone  20   j . This enables the anchors  50   j  and  52   j  to be pressed against the outer side surface  250  of the bone  20   j . Therefore, tension forces in the suture  38   j  are transmitted through the anchors  50   j  and  52   j  to the bone  20   j.    
         [0170]    By inserting the tubular member  240  into the passage  40   j , the portions of the passage disposed on opposite sides of the fracture  26   j  are maintained in alignment. The tubular member  240  may be flexible to enable the tubular member to be inserted into a nonlinear passage  40   j  through the bone  20   j . The tubular member  240  may be formed of metal or a polymeric material. If the tubular member  240  is formed of a polymeric material, it may be preferred to form the tubular member from a biodegradable or bioerodible copolymer.  
         [0171]    In accordance with one of the features of this embodiment of the invention, the tubular member  240  is formed of bone. By forming the tubular member  240  of bone, tissue growth into the tubular member is promoted. The tubular member  240  may be packed with bone or bone graft. The tubular member  240  may contain bone osteoinductive protein (BMP). Bone growth inducing materials containing apatite compositions with collagen and/or other materials may be utilized. The tubular member  240  may be formed of either human or animal bone.  
         [0172]    It is contemplated that it may be preferred to form the tubular member  240  of freeze dried human bone obtained from a cadaver. The freeze dried bone will absorb body fluids. As this occurs, the tubular member  240  will expand and grip the two sections  22   j  and  24   j  of the bone  20   j . The body fluids will be conducted into bone growth promoting materials contained in the tubular member  240 . If desired, antibiotics and/or other medicants may be provided in the bone or bone graft with which the tubular member  240  is packed. Of course, the tubular member  240  may be formed of other materials, such as biodegradable materials, if desired.  
         [0173]    The suture  38   j  is formed into a loop which extends through the openings  64   j  and  66   j  in the anchor  50   j . At this time, the suture  38   j  has a length which is substantially greater than the length illustrated in FIG. 2. The cylindrical anchor  50   j , with the suture  38   j  connected thereto, is then positioned in axial alignment with the tubular member  240  which extends through the passage  40   j . Thus, the anchor  50   j  is moved to an orientation in which a longitudinal central axis of the anchor is coincident with the longitudinal central axis of the cylindrical passage  246  in the tubular member  240  which extends through the passage  40   j  in the bone  20   j.    
         [0174]    The leading end  58   j  of the anchor  50   j  is then moved into the cylindrical tubular member  240  which forms a liner for the passage  40   j . A pusher member pushes the anchor  50   j  from an upper (as viewed in FIG. 13) end  244  of the tubular member  240  along the passage  246  in the tubular member  240  and the passage  40   j  in the bone  20  and through the outlet  84   j  from the passage. As the anchor  50   j  moves through the passages  40   j  and  246 , the suture  38   j  is pulled through the passages by the anchor.  
         [0175]    The orientation of the anchor  50   j  is then changed from an orientation in which the longitudinal central axis of the anchor  50   j  is aligned with the coincident longitudinal central axes of the passages  40   j  and  246  to an orientation in which the longitudinal central axis of the anchor  50   j  extends generally perpendicular to the longitudinal central axis of the passages  40   j  and  246 , i.e., the orientation shown in FIG. 13. To pivot the anchor  50   j  to the orientation shown in FIG. 13, as the anchor emerges from the outlet  84 , the suture  38   j  is tensioned. The combination of the tension in the suture  38   j  and force applied against the trailing end  60   j  of the anchor  50   j  by the pusher member causes the anchor to pivot about the trailing end  60   j  of the anchor. The pusher member is then withdrawn and the suture  38   j  tensioned to move the anchor to the position shown in FIG. 13 in a manner similar to that described in the aforementioned U.S. Pat. Nos. 5,527,343 and 5,534,012.  
         [0176]    Although it is believed that it may be preferred to change the orientation of the anchor  50   j  after it has emerged from the passages  40   j  and  246 , the anchor could be blocked from reentering the passage in other ways if desired. Thus, the anchor could expand after emerging from the passages  40   j  and  246 . This could be accomplished by having spring biased arms held in a retracted position by engagement of spring biased arms with the inner side surface of the tubular cylindrical member  240  which lines the passage  40   j . Upon emerging from the passages  40   j  and  246 , the arms would move outward under the influence of spring forces and extend radially outward beyond the edge of the exit from the passage  40   j . If desired, the anchor  50   j  could be constructed so as to expand in a manner similar to that disclosed in U.S. Pat. No. 5,397,331 and/or U.S. Pat. No. 4,409,974.  
         [0177]    Rather than expanding under the influence of stored energy, such as spring force, the anchor  50   j  could expand by absorbing body fluids. Thus, the anchor  50   j  may be compressed when it moves through the passages  40   j  and  246  and will expand and absorb body fluids after emerging from the passages  40   j  and  246 . It is contemplated that the anchor  50   j  could be constructed so as to expand in any one of the ways disclosed in U.S. patent application Ser. No. 08/699,553 filed Aug. 19, 1996 by Peter M. Bonutti and entitled “Suture Anchor”.  
         [0178]    Once the anchor  50   j  has been moved through the passage  246 , the passage is packed with bone particles and/or bone graft. The bone particles and/or bone graft contains bone growth inducing materials. In addition, the bone particles and/or bone graft may contain medicinal substances along with osteoinductive protein.  
         [0179]    The limbs  72   j  and  74   j  of the suture  38   j  are then threaded through openings  64   j  and  66   j  in the second suture anchor  52   j . The limbs  72   j  and  74   j  of the suture  38   j  are tensioned and the second anchor  52   j  is pressed against the outer side surface  250  of the bone  20   j . While a predetermined tension force is maintained in the limbs  72   j  and  74   j  of the suture  38   j , the knot  78   j  is tied in the suture to interconnect the two suture anchors  50   j  and  52   j  with the suture  38   j . The suture  38   j  is then trimmed to the desired length.  
         [0180]    Once the knot  78   j  has been tied between the limbs  72   j  and  74   j  of the suture  38   j , the tension in the suture  38   j  presses the side surfaces  28   j  and  30  of the fracture  26   j  together. This pressure between the side surfaces  28  and  30   j  of the fracture  26   j  is maintained by the suture  38  and suture anchors  50   j  and  52   j  until the fracture heals. It is believed that it may be preferred to form the suture  38   j  and suture anchors  50   j  and  52   j  of a biodegradable material which, after the fracture  26   j  has healed, will dissolve in the patient&#39;s body.  
         [0181]    The cylindrical tubular member  240  which is inserted into the passage  40   j  through the bone  20   j  performs the dual functions of lining the inside of the passage  40   j  and maintaining the two sections  22   j  and  24   j  of the bone in alignment. The cylindrical tubular member  240  could have a slot formed in a side wall of the tubular member to facilitate insertion of the tubular member into the passage  40   j . It is contemplated that the cylindrical tubular member  240  could be left in the passage  40   j  after the bone securing assembly  32   j  has been installed. If the slotted or unslotted cylindrical tubular member  240  is to be left in the passage  40   j , the cylindrical tubular member  240  may be formed of a biodegradable or bioerodible copolymer. When the cylindrical tubular member remains in the passage  40   j , the suture  38   j  extends through the tubular member.  
         [0182]    Although only a knot  78   j  has been shown in FIG. 13 adjacent to the second anchor  52   j , a suture retainer could be provided to further hold the limbs  72   j  and  74   j  of the suture  38   j . If a suture retainer is to be used in association with the knot  78   j , the suture retainer will be moved along the limbs of the suture  38   j  toward the knot before the limbs  72   j  and  74   j  of the suture are trimmed to the short length shown in FIG. 13. The suture retainer would then be plastically deformed to grip the limbs  72   j  and  74   j  of the suture  38   j . Thereafter, the suture limbs  72   j  and  74   j  would be trimmed to a desired length.  
         [0183]    Although it is preferred to use a suture as the force transmitting member  38   j , it should be understood that the anchors  50   j  and  52   j  could be interconnected by other force transmitting members, such as a rod formed of bone. Although the anchors  50   j  and  52   j  have constructions which enable them to be used with a suture, the anchors could be constructed so as to be used with other types of force transmitting members. For example, the anchors  50   j  and  52   j  could have thread convolutions to engage thread convolutions on a force transmitting member formed by a rod.  
         [0184]    In the embodiment of the invention illustrated in FIG. 13, the member  240  is tubular. However, it is contemplated that a solid member could be used to transmit force to bone on opposite sides of the fracture  26   j . Thus, the member  240  could be a solid cylindrical member formed of bone. The cylindrical member may be formed of freeze dried bone.  
         [0185]    When the member  240  is a solid member, the suture or other force transmitting member  38   j  is eliminated. The solid member formed of bone becomes the force transmitting member. Anchors, corresponding to the anchors  50   j  and  52   j , are connected to opposite ends of the solid member  240  formed of bone. The anchors may have internal thread convolutions which engage external thread convolutions on the solid member  240  formed of bone. Of course, other known connectors could be utilized to connect anchors with opposite ends of the solid member  240  formed of bone.  
       NONLINEAR SUTURE PASSAGE—TUBULAR MEMEBER  
       [0186]    In the embodiment of the invention illustrated in FIG. 13, the passage  40   j  through which the suture  38   j  extends has a linear configuration. In the embodiment of the invention illustrated in FIG. 14, the passage through which the suture extends has a nonlinear configuration. Since the embodiment of the invention illustrated in FIG. 14 is generally similar to the embodiment of the invention illustrated in FIGS.  1 - 13 , similar numerals will be utilized to identify similar components, the suffix letter “k” being associated with the components of the embodiment of the invention illustrated in FIG. 14 to avoid confusion.  
         [0187]    A bone  20   k  as a fracture  26   k  which divides the bone into two sections  22   k  and  24   k . Opposite side surfaces  28   k  and  30   k  of the fracture  26   k  are pressed together by a bone suture assembly  32   k . The bone suture assembly  32   k  includes a suture  38   k  which extends between first and second suture anchors  50   k  and  52   k.    
         [0188]    The suture  38   k  is disposed in a passage  40   k  having a nonlinear configuration. Thus, the passage  40   k  includes a first section  140   k  which is skewed relative to a second section  142   k  of the passage  40   k . A bend  144   k  is formed in the passage  40   k  at an intersection  146   k  of the first and second sections  140   k  and  142   k  of the passage  40   k . The flexible suture  38   k  extends around the bend  144   k  along a nonlinear path between the suture anchors  50   k  and  52   k . At the bend  144   k , the suture  38   k  applies force against the section  24   k  of the bone  20   k  urging the section  24   k  toward the left (as viewed in FIG. 5). This force presses the sections  22   k  and  24   k  of the bone  20   k  firmly together at the fracture  26   k.    
         [0189]    The suture anchors  50   k  and  52   k  have the same cylindrical construction as the suture anchors  50 ,  52 ,  50   j  and  52   j  in the embodiment of the invention illustrated in FIGS. 2 and 13. A knot  78   k  (FIG. 14) is provided between limbs of the suture  38   k  to maintain a desired tension in the suture  38   k . This tension pulls the suture anchors  50   k  and  52   k  toward each other. In addition, this tension presses the section  24   k  of the bone  20   k  firmly against the section  22   k  of the bone at the fracture  26   k.    
         [0190]    The first section  140   k  of the passage  40   k  is formed at an angle to and extends through a longitudinal central axis of the generally cylindrical bone  20   k . The second section  142   k  of the passage  40   k  is formed in a direction perpendicular, i.e., along a radius, of the generally cylindrical bone  20   k . The two sections  140   k  and  142   k  of the passage  40   k  terminate in the spongy cancellous bone tissue  44   k.    
         [0191]    When the suture assembly  32   k  is to be used to treat the fracture  26   k  in the bone  20   k , the two sections  22   k  and  24   k  of the bone are pressed together at the fracture  26   k  to align the side surfaces  28   k  and  30   k  of the fracture. A drill or other hole forming apparatus is then used to form the first section  140   k  of the passage  40   k . The drill or other hole forming apparatus is then used to form the second section  142   k  of the passage  40   k . When the second section  142   k  of the passage  40   k  intersects the first section  140   k  of the passage  40   k , formation of the section  142   k  of the passage  40   k  is interrupted.  
         [0192]    Once the nonlinear passage  40   k  has been formed in the two sections  22   k  and  24   k  of the bone  20   k , a tubular cylindrical liner  240   k  is inserted into the passage  40   k . The tubular cylindrical liner  240   k  is formed by two separate cylindrical tubular members  252  and  254  which are inserted at opposite ends of the passage  40   k . Alternatively, the tubular cylindrical liner  240   k  may be formed by a single flexible tubular member which is inserted into the section  140   k  of the passage  40   k  and then moved around the bend  144   k  into the section  142   k  of the passage  40   k .  
         [0193]    It is believed that it may be preferred to form the tubular members  252  and  254  of bone. The bone forming the tubular members  252  and  254  may be either human or animal bone. The tubular members  252  and  254  may be formed of freeze dried human bone.  
         [0194]    The leading end  242   k  of the tubular member  252  is disposed in the compact outer layer  42   k  of the bone  20   k . Similarly, the trailing end  244   k  of the tubular member  254  is disposed in the compact outer layer  42   k  of the bone  20   k . The tubular member  252  extends across the fracture  26   k  and stabilizes the two sections  22   k  and  24   k  of the bone  20   k . Since the end portions  242   k  and  244   k  of the tubular members  252  and  254  are disposed in the compact outer layer  42   k  of the bone  20   k , the tubular members are solidly supported and hold the two sections  22   k  and  24   k  of the bone  20   k  in alignment at the fracture  26   k.    
         [0195]    The opposite ends  242   k  and  244   k  of the tubular members  252  and  254  are axially spaced from a generally cylindrical outer side surface  250   k  on the bone  20   k . This enables the anchors  50   k  and  52   k  to be pressed against the outer side surface  250   k  of the bone  20   k . Therefore, tension forces in the suture  38   k  are transmitted through the anchors  50   k  and  52   k  to the bone  20   k.    
         [0196]    The cylindrical anchor  50   k , with the suture  38   k  connected thereto, is then positioned in axial alignment with the section  142   k  of the passage  40   k . The leading end  58   k  of the anchor  50   k  is then moved into the section  142   k  of the passage  40   k  lined by the tubular member  254 . A flexible pusher member applies force against the trailing end  60   k  of the anchor  50   k  and pushes the anchor around the bend  144   k  and through the section  140   k  of the passage  40   k  lined by the tubular member  252 .  
         [0197]    Alternatively, a flexible wire or other member could be inserted into the section  140   k  of the passage  40   k . The wire would move around the bend  144   k  and extend outward from the section  142   k  of the passage. The wire would then be connected with the anchor  50   k  and suture  38   k . The leading end  58   k  of the anchor  50   k  would then be inserted into the section  142   k  of the passage  40   k . Tension on the wire would pull the anchor  50   k  around the bend  144   k  and out of the section  140   k  of the passage  40   k.    
         [0198]    The passages in the tubular members  252  and  254  may be packed with bone particles and/or bone graft. Bone osteoinductive protein (BMP) may be provided in the tubular members. Antibiotics and/or other medicants may be included along with collagen.  
         [0199]    The suture  38   k  is then threaded through openings in the suture anchor  52   k . The suture  38   k  is then tensioned and the second anchor  52   k  is pressed against the outer side surface of the bone  20   k . While a predetermined tension force is maintained in the suture  38   k , the knot  78   k  is tied.  
         [0200]    In the illustrated embodiment of the invention, the two sections  140   k  and  142   k  of the passage  40   k  have a straight cylindrical configuration. However, it is contemplated that the sections  140   k  and  142   k  of the passage  40   k  could have a different configuration if desired. For example, the section  140   k  and/or  142   k  of the passage  40   k  could have a nonlinear central axis and could have a noncircular cross-sectional configuration of desired.  
         [0201]    Body tissue, corresponding to the body tissue  132  of FIG. 4 could be disposed between the anchor  50   k  and/or  52   k  and the bone  20   k . Although the suture  38   k  has been illustrated as having a pair of limbs or sections which extend between the anchors  50   k  and  52   k , the suture  38   k  could have a single limb or section if desired. The anchor  50   c  could mechanically expand, by absorbing body liquid or under the influence of expansion springs, after the anchor has emerged from the passage  40   k  to prevent the anchor from being pulled back through the passage.  
       Retainer and Tubular Member  
       [0202]    In the embodiment of the invention illustrated in FIG. 13, a pair of suture anchors  50   j  and  52   j  are connected with the suture  38   j  to maintain tension in the suture and pressure against opposite side surfaces  28   j  and  30   j  of the fracture  26   j . In the embodiment of the invention illustrated in FIG. 15, a suture retainer is used in place of one of the suture anchors. Since the embodiment of the invention illustrated in FIG. 15 is generally similar to the embodiment of the invention illustrated in FIG. 13, similar numerals will be utilized to designate similar components, the suffix letter “m” being associated with the embodiment of the invention illustrated in FIG. 15 to avoid confusion.  
         [0203]    A bone  20   m  has sections  22   m  and  24   m  which are separated by a fracture  26   m . The fracture  26   m  has side surfaces  28   m  and  30   m  which are pressed together by a bone suture assembly  32   m . A suture  38   m  extends through a cylindrical passage  40   m  which extends diametrically through the generally cylindrical bone  20   m . The suture  38   m  has a pair of limbs or sections  72   m  and  74   m  which are connected with a suture anchor  50   m . The suture anchor  50   m  has the same construction as the suture anchor  50  of FIG. 2.  
         [0204]    Once the passage  40  has been formed in the two tubular sections  22   m  and  24   m  of the bone  20   m , a tubular cylindrical member  240   m  is installed into the passage  40   m  and extends diametrically through the bone  20   m . The leading end  242   m  of the cylindrical member  240   m  is aligned with a circular outlet  84   m  from the passage  40   m . The opposite or trailing end  244   m  of the tubular member  240   m  is aligned with a circular inlet  86   m  to the passage  40   m.    
         [0205]    The tubular member  240   m  has a thin cylindrical wall which engages the sections  22   m  and  24   m  of the bone  20   m . A cylindrical inner side surface of the tubular member  240   m  defines a cylindrical passage  246   m  having a diameter which is only slightly less than the diameter of the passage  40   m . The tubular member  240   m  is formed of bone. Alternatively, the tubular member  240   m  could be formed of a biodegradable material.  
         [0206]    The leading end  242   m  of the tubular member  240   m  is disposed in the compact outer layer  42   m  of the bone  20   m . Similarly, the trailing end  244   m  of the tubular member  240   m  is disposed in the compact outer layer  42   m  of the bone  20   m . The tubular member  240   m  extends across the fracture  26   m  and stabilizes the two sections  22   m  and  24   m  of the bone  20   m . Since the opposite end portions of the tubular member  240   m  are disposed in the compact outer layer  42   m  of the bone  20   m , the tubular member is solidly supported and holds the two sections  22   m  and  24   m  of the bone  20   m  in alignment at the fracture  26   m.    
         [0207]    The opposite ends  242   m  and  244   m  of the tubular member  240   m  are axially spaced from a generally cylindrical outer side surface  250   m  on the bone  20   m . This enables the anchors  50   m  and  92   m  to be pressed against the outer side surface  250   m  of the bone  20   m . Therefore, tension forces in the suture  38   m  are transmitted through the anchors  50   m  and  92   m  to the bone  20   m.    
         [0208]    The tubular member  240   m  is formed of freeze dried human bone. The tubular member  240   m  is packed with bone and/or bone graft. The tubular member  240   m  also contains bone osteoinductive protein (BMP). Suitable medicants may be provided in the tubular member  240   m.    
         [0209]    A suture retainer  92   m  is used in place of the suture anchor  52  of FIG. 2. The suture retainer  92   m  (FIG. 15) has a spherical configuration. A cylindrical passage  94   m  extends through the center of the spherical suture retainer  92   m . The sections  72   m  and  74   m  of the suture  38   m  extend around the spherical outer side surface of the suture retainer  92   m . Thus, a loop is formed in each of the sections  72   m  and  74   m  around portions of the suture retainer  92   m.    
         [0210]    If desired, the suture retainer  92   m  could have a different configuration. For example, the suture retainer  92   m  could have an oval or elliptical configuration. Although the passage  94   m  has a linear central axis, the passage could have a nonlinear central axis. If desired, a plurality of passages having the same or different configurations could be provided in the suture retainer  92   m.    
         [0211]    After the suture  38   m  has been inserted through the suture retainer  92   m , the suture retainer  92   m  is moved along the sections  72   m  and  74   m  of the suture  38   m  toward the bone  20   m . The suture retainer  92   m  is formed as one piece of a polymeric material having a relatively low coefficient friction. Therefore, the two sections  72   m  and  74   m  of the suture  30   m  can readily slide along the surfaces of the suture retainer  52   m  while the suture retainer moves toward the bone  20   m.    
         [0212]    A predetermined tension is maintained in the sections  72   m  and  74   m  of the suture  38   m  while the suture retainer  92   m  is pressed against the bone  20   m . This results in the suture  38   m  being pulled tightly against the suture anchor  50   m . The tension in the suture  38   m  is effective to press the suture anchor  50   m  and retainer  92   m  against opposite sides of the bone  20   m  with a predetermined force.  
         [0213]    While the sections  72   m  and  74   m  of the suture  38   m  are being tensioned with a predetermined force, the suture retainer  92   m  is plastically deformed in the same manner as previously described in conjunction with the embodiment of the invention illustrated in FIG. 3. To plastically deform the suture retainer  92   m , a plurality of force applying or clamp members are pressed against the suture retainer with a predetermined minimum force. The force applied against the suture retainer  92   m  by the force applying members is sufficient to cause plastic deformation of the material of the suture retainer.  
         [0214]    The force is applied against the suture retainer  92   m  while the suture retainer is at a temperature which is below the transition temperature of the biodegradable polymer which forms the suture retainer  92   m . Thus, the suture retainer  92   m  is at approximately the same temperature as the bone  20   m  when the force is applied against the suture retainer. The force causes the material of the suture retainer  92   m  to flow and grip the sections  72   m  and  74   m  of the suture  38   m.    
         [0215]    The suture retainer  92   m  may be formed of many different materials. However, it is believed that it will be preferred to form the suture retainer  92   m  of a biodegradable polymer. One biodegradable polymer which may be utilized is polycaperlactone. Alternatively, the suture retainer  92   m  could be formed of polyethylene oxide terephthalate or polybutylene terephthalate. It is also contemplated that other biodegradable or bioerodible copolymers could be utilized.  
         [0216]    Although it is preferred to form the suture retainer  92   m  of a biodegradable material, the suture retainer could be formed of a material which is not biodegradable. For example, the suture retainer  92   m  could be formed of an acetyl resin, such as “DELRIN” (trademark). Alternatively, the suture retainer  92   m  could be formed of para-dimethylamino-benzenediaz-o sodium sulfonate, such as “DEXON” (trademark). The construction of the suture retainer  92   m  and the manner in which is cooperates with the suture  38   m  is the same as is disclosed in U.S. patent application Ser. No. 08/905,084 filed Aug. 1, 1997 by Peter M. Bonutti et al. and entitled “Method and Apparatus for Securing a Suture”.  
         [0217]    The suture retainer  92   m  is plastically deformed to grip the limbs  72   m  and  74   m  of the suture  38   m . However, the suture retainer  92   m  could be constructed so as to be mechanically actuated to grip the suture  38   m . If desired, a combination of a mechanical gripping action and plastic deformation could be utilized by a retainer to grip the suture  38   m.    
       Conclusion  
       [0218]    In view of the foregoing description, it is apparent that the present invention relates to a method of securing sections  22  and  24  of a fractured bone  20 . Sections  22  and  24  of a fractured bone  20  are held against movement relative to each other by a force transmitting member, such as a suture  38 , which extends through a passage  40  in the bone. The passage  40  in the bone may have a linear or nonlinear configuration. Tension is maintained in the force transmitting member  38  to press surfaces  28  and  30  on the fracture together by securing anchors  50  and  52  or suture retainers  92  to opposite ends of the force transmitting member  38 . It is believed that a suture  38  may advantageously be used as the force transmitting member.  
         [0219]    A tubular member  240  is positioned in a linear passage (FIGS. 13 and 15) or a nonlinear passage (FIG. 14) through the bone  20 . The tubular member  240  extends into portions of the passage  40  on opposite sides of the fracture  26 . End portions of the tubular member may be positioned in a compact outer layer  42  of the bone. The tubular member  240  may be formed of bone. The force transmitting member  38  may be formed of bone or other body tissue.