Abstract:
Attachment of sutures to bone is achieved by forming a recess in the bone having a cylindrical channel surrounding a bone core and then inserting a hollow anchor body into the recess and over the bone core. Suture material is attached using openings in the anchor body and the suture material may be pinched between the inside and outside surfaces of the anchor body and the bone material.

Description:
CROSS-REFERENCED TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    I. Field of the Invention 
         [0004]    The present invention relates to medical implants. More particularly, this invention relates to suture anchors used to attach soft tissue to bone. 
         [0005]    II. Related Art 
         [0006]    Surgeons have employed various types of suture anchors for decades for a variety of surgical applications. Suture anchors provide a surgeon with a means for attaching two pieces of tissue together so that they may heal. The tissues typically are tendon, ligament, or bone. 
         [0007]    Prior to the development of suture anchors, surgeons would typically pass the suture material directly through bone utilizing sharp, trocar-tipped needles. Clamps or other similar instruments were sometimes used instead of sutures. In either case, a rather large surgical exposure was required resulting in increased surgical morbidity to the patient and longer healing times. The advent of suture anchors allowed the refinement of a variety of surgical procedures. Rather than using a conventional, open approach requiring a large incision, the use of suture anchors permitted the surgeon to employ a minimally invasive arthroscopic approach leading to less surgical morbidity and potentially faster healing rates for patients. 
         [0008]    Suture anchors typically comprise two components—the body of the anchor and a suture material to be anchored to the bone. The body of the anchor can be made of a variety of different materials that are biocompatible, easily sterilized and strong enough to withstand the forces that may be exerted on the anchor. Such materials include, without limitation, titanium, alloys of stainless steel, polyether-ether ketone (PEEK), poly-1-lactic acid, and other biocompatible materials. An example of a material used to form the sutures is a polyester braid. The suture material is used to join tissue to the anchor body and the anchor body couples the suture material to a bone, providing an “anchor point” to the bone. 
         [0009]    Prior art suture anchors typically have one of several designs that permit the body of the suture anchor to be secured to the bone. Most of these designs incorporate a solid body with exterior threads or ridges. When the anchor is a solid body incorporating exterior threads, a pilot hole is typically drilled into the bone and then the anchor body is screwed into the pilot hole and the threads prevent the anchor body from pulling out of the bone. Similarly, when a solid anchor body having ridges is employed, a pilot hole is drilled and the anchor body is impacted into the bone such that the ridges prevent the anchor body from being pulled out. Some anchor bodies are designed to expand such that the entire body or an element of the body expands as the anchor body is driven into the bone to prevent the anchor body from being pulled out of the bone. 
         [0010]    Commercial suture anchors may come preloaded with the suture material. Alternatively, loading the suture anchor with the suture material may be performed by the surgeon. When the suture anchor comes preloaded, the anchor body is typically placed into the bone at an anchor point and then the suture material is passed through or around a piece of tissue to be joined to the bone at the anchor point. The sutures are then tied, securing the piece of tissue to the anchor body which has already been placed in the bone at the anchor point. When the suture anchors are not preloaded with suture material, free sutures are typically passed by the surgeon through or around a piece of tissue that the surgeon wishes to anchor to the bone. The sutures are then fed through the anchor body and the anchor body is impacted into the bone pulling the tissue down to the anchor point. 
         [0011]    The sutures are secured within the anchor body in various manners. In some situations, this fixation is made without tying knots and the anchor is referred to as a “knotless” anchor. When knotless anchors are used, an internal locking mechanism is provided such that the sutures are locked to the anchor body via the locking mechanism. The locking mechanism typically operates by pinching the sutures. In other cases, the sutures are extended between the bone and the external surfaces of the anchor body such that when the anchor body is inserted into the bone at the anchor point, the sutures are pinched between the bone and the anchor body. 
         [0012]    While a number of surgical procedures have been successfully performed using prior art suture anchors, surgeons sometimes encounter difficulties implanting such suture anchors arthroscopically. Thus, to complete the surgical procedure, a large surgical exposure is created. This serves to increase trauma, pain, risk of nerve and tissue damage, and healing time. Further, during recovery and before healing is complete, excessive forces may be applied to the sutures and anchor body by the tendon, ligament or bone which can result in the suture anchor dislodging from the bone or the sutures dislodging from the anchor body. Additional surgical repair is required should such dislodging occur. Still further, upon removal or dislodging of currently existing suture anchors, a cylindrical defect is left in the host bone. Such a defect may serve as an impediment to placement of new anchors for revision surgery. Additionally, many “knotless” suture anchors have complex internal locking mechanisms that may present technical difficulties for the surgeon performing the procedure during actuation of the locking mechanism. As such, there is a real need for an improved suture anchor which can be readily and easily implanted arthroscopically, is simple to use, will be securely bound to the bone, and at the same time will securely couple the sutures to the anchor body and bone. 
       SUMMARY OF THE INVENTION 
       [0013]    An improved suture anchor design provides an anchor body having an open top, an open bottom, and a generally cylindrical wall extending between the open top to the open bottom. The cylindrical wall defines inner engagement surfaces surrounding a channel extending from the open top to the open bottom and an outer engagement surface. Use of the suture anchor incorporating these features permits the anchor body to be used with a uniquely shaped recess prepared in the bone. Such a recess extends inwardly from an exposed surface of the bone at the desired point of attachment (i.e., the anchor point) and comprises a cylindrical hole extending inwardly from the exposed surface to a base. The cylindrical hole surrounds a bone core extending from the base toward the exposed surface of the bone. 
         [0014]    Such a recess has at least two engagement surfaces, specifically an outer bone surface at the outside of the cylindrical wall and also an inner bone surface, i.e., surface of the bone core. The anchor body is adapted to permit the cylindrical wall (or at least a portion thereof) to be inserted into the cylindrical hole of the recess such that the bone core resides in the channel of the anchor body. As such, the outer engagement surface of the anchor body engages the outer bone surface of the recess and the inner engagement surface of the anchor body engages the bone core. This serves to substantially increase the surface area of the bone engaged by the anchor body for increased holding power. This also results in substantially less bone material being removed when forming the recess than is the case with traditional solid body bone anchors. 
         [0015]    In some embodiments the anchor body may have vents through the walls of the anchor to permit vascular flow and bone growth between the bone along the external engagement surface of the anchor and the central bone core against the internal engagement surface. Bone growth through these vents would serve to further reinforce anchor fixation to bone, preventing dislodgement. 
         [0016]    To further increase the holding power of the bone anchor, ridges or threads may be provided on either the outer engagement surface of the anchor body, the inner engagement surface of the anchor body or both the inner and outer engagement surfaces of the anchor body. Various structures may be coupled to the anchor body to permit preloading of the anchor body with suture material. 
         [0017]    More specifically, in one embodiment the anchor body may be designed to be impacted directly into the recipient recess with external ridges present oriented in such a manner as to achieve a friction fit between the external engagement surface of the anchor and the surrounding bone, thereby resisting extraction or pullout of the anchor body. In other embodiments, internal ridges may also be added to the internal surface of the device to provide a similar friction fit between the internal engagement surface of the anchor and the central core of bone. The anchor body may alternatively, in other embodiments, be designed to be screwed into place with threads present on the external engagement surface of the anchor that will engage the surrounding bone. Internal threads may also be added to the internal engagement surface of the device to provide a similar threaded purchase against the central core of bone. The pitch of the internal threads would match that of the external threads to permit the anchor body to advance in the same fashion with engagement of both external and internal threads. 
         [0018]    Various structures may be coupled to the anchor body to permit loading of the anchor body with suture material. For example, with a threaded design in which threads are fashioned along the external surface of the anchor body, permitting the anchor to be screwed into the recipient cylindrical socket, a short, hollow, cylindrical cap may be loaded with suture and positioned at the distal tip of the anchor such that in the process of screwing the anchor body into place the cap is driven into and secured in the bone at the distal end of the anchor body. 
         [0019]    Using the hollow anchor body described above with a hollow center that embraces a bone core is particularly advantageous when employing a knotless suturing technique. The suture material is held more securely to the anchor body and the bone because the suture material is not only captured between the outer engagement surface of the anchor body and the outer bone surface, but is also captured between the inner engagement surface of the anchor body and the central bone core. These two areas of engagement may be provided by creating a loop of suture material which is adapted to reside between the outer engagement surface of the anchor body and the outer bone surface with other portions of the suture material extend into and through the channel of the suture anchor such that these portion is of the suture material reside between the inner engagement surface of the anchor body and bone core. The suture material may pass through the open bottom of the anchor body. Alternatively, an orifice or passageway may be provided through the cylindrical wall between the inner engagement surface and the outer engagement surface adjacent the open bottom of the anchor body. Such an orifice or passageway reduces the risk that the suture material will be cut by the bottom of the anchor body as it is driven into the bone recess formed at the anchor point. The suture material may also be passed through an orifice or passageway in a short, hollow, cylindrical cap that engages the distal tip of the anchor body in a manner as described above. 
         [0020]    The suture anchor may be provided as part of a kit that also includes a tool for forming a recess in the bone at an anchor point of the type described above. For those embodiments of the anchor device possessing threads along the engagement surface(s), the kit may also include a tool for forming and tapping a recess in the bone at an anchor point of the type described above. The kit may also include an insertion tool for advancing the anchor body into the recess until the open bottom of the anchor body reaches the base of the recess with the bone cores residing within and extends up through the channel of the anchor body. 
         [0021]    Alternatively, in some embodiments, the distal tip of the anchor body (or a distal cap associated therewith) may be reinforced with a sharpened ring of metal alloy that permits the anchor body to form its own recess as it is being impacted into the recipient bone, without the need for prior formation of the recess. In such embodiments, the anchor body would be considered “self-punching” as it would form its own recess. 
         [0022]    The anchor body and insertion tool are, of course, adapted to permit the anchor body to be coupled to the insertion tool during the insertion process and then decoupled from each other to permit extraction of the insertion tool while leaving in place the anchor body and any sutures attached thereto. The insertion tool may include a channel that is in communication with the channel of the anchor body when the two are joined together. The insertion tool may also have a separate passageway extending from its channel out of a portion of the wall of the insertion tool. As such, suture material may be fed (i) in through the orifice in the wall of the anchor body, (ii) up through the channel of the anchor body, (iii) into the channel of the insertion tool, and then (iv) out through the passageway of the insertion tool such that, upon insertion of the anchor body, the suture material is pinched between not only the anchor body and the outer bone surface, but also between the anchor body and the bone core. A wire loop or loops may be provided to facilitate the passage of suture material through said passageways. 
         [0023]    Other features and advantages of the present invention will become apparent from the following detailed description of the invention, which refers to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description and with reference to the following drawings in which like numerals and the several views refer to corresponding parts. 
           [0025]      FIG. 1  is a cross-section of a piece of bone showing a recess formed therein at an anchor point. 
           [0026]      FIG. 2  is a top view of a piece of bone showing a recess form therein at an anchor point. 
           [0027]      FIG. 3  is a side elevational view of a first embodiment of an anchor body. 
           [0028]      FIG. 4  is a top view of the anchor body of  FIG. 3 . 
           [0029]      FIG. 5  is a bottom view of the anchor body of  FIG. 3 . 
           [0030]      FIG. 6  shows the anchor body of  FIG. 3  implanted in a piece of bone at an anchor point, the bone being shown in cross-section. 
           [0031]      FIG. 7  is a side elevational view of a second embodiment of an anchor body. 
           [0032]      FIG. 8  shows the anchor body of  FIG. 7  implanted in a piece of bone at an anchor point, the bone being shown in cross-section. 
           [0033]      FIG. 9  is a side elevational view of a third embodiment of an anchor body. 
           [0034]      FIG. 10  is a top view of the anchor body of  FIG. 9 . 
           [0035]      FIG. 11  is a bottom view of the anchor body of  FIG. 9 . 
           [0036]      FIG. 12  shows the anchor body of  FIG. 9  implanted in a section of bone at an anchor point, the section of bone being illustrated in cross-section. 
           [0037]      FIG. 13  is a side elevational view of a fourth embodiment of an anchor body. 
           [0038]      FIG. 14  shows the anchor body of  FIG. 13  implanted in a section of bone at an anchor point, the bone being shown in cross-section. 
           [0039]      FIG. 15  is side elevational view of a fifth embodiment of an anchor body. 
           [0040]      FIG. 16  is a top view of the anchor body shown in  FIG. 15 . 
           [0041]      FIG. 17  shows the anchor body of  FIG. 15  aligned with the recess of  FIGS. 1 and 2  (left) and implanted in the recess (right). 
           [0042]      FIG. 18  is a view of a sixth embodiment of an anchor body and distal cap wherein the anchor body and cap are aligned with the recess of  FIGS. 1 and 2  (left), are aligned with the recess and joined together (center) and implanted in the recess (right). 
           [0043]      FIG. 19  is a cross-section of a portion of the cylindrical wall of an anchor body having both external and internal threads or ridges. 
           [0044]      FIG. 20  is a perspective view of a recess forming tool adapted to form a recess in a bone of the type shown in  FIGS. 1 and 2 . 
           [0045]      FIG. 21  shows an anchor body insertion tool. 
           [0046]      FIG. 22  shows and anchor body insertion tool and an anchor body. 
           [0047]      FIG. 23  shows the anchor body insertion tool and anchor body of  FIG. 22  joined together. 
           [0048]      FIG. 24  shows an anchor body and insertion tool with a loop of suture material fed through the anchor body and insertion tool. 
           [0049]      FIG. 25  shows in cross-section an anchor body positioned within a recess at an anchor point and a piece of suture material secured in place at the anchor point by the anchor body. 
           [0050]      FIG. 26  shows a seventh embodiment of an anchor body aligned with the recess of  FIGS. 1 and 2  (left), partially implanted (center), and fully implanted in the recess (right). 
       
    
    
     DETAILED DESCRIPTION 
       [0051]    In the following detailed description, references made to various exemplary embodiments in which the invention may be practiced. These embodiments are described with sufficient detail to enable those skilled in the art to practice the invention, and it is understood that other embodiments may be employed, and that structural and other changes may be made without departing from the spirit or scope of the present invention. 
         [0052]    This description of the preferred embodiment is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top” and “bottom”, “under”, as well as derivatives thereof (e.g., “horizontally”, “downwardly”, “upwardly”, “underside”, etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “connected”, “connecting”, “attached”, “attaching”, “joined”, and “joining” are used interchangeably and refer to one structure or surface being secured to another structure or surface or integrally fabricated in one piece unless expressly described otherwise. 
         [0053]      FIGS. 1 and 2  illustrate a recess that is formed at an anchor point in a section of bone when the various embodiments described below are employed. More specifically, these drawings show, in cross-section, a portion  1  of bone having an exposed surface  2 . Formed into the bone  1  from the exposed surface  2  is a cylindrical hole  4  having a base  6 . The cylindrical hole  4  surrounds a bone core  8 . As such, the recess has an inner bone surface  10  and an outer bone surface  12 . Such a recess may be forms using any of a variety of tools. An example of such a recess forming tool  110  is shown in  FIG. 20 . The recess forming tool  110  has a hollow cylindrical body  112  extending between a cutting edge  114  and a driving end  118 . The cutting edge  114  may be serrated as shown or may be a single sharpened edge. The cutting edge surrounds an opening  116 . The recess forming tool  110  may be employed as a punch or coupled to a rotary tool and used like a hole saw. 
         [0054]      FIGS. 3-6  illustrate a first embodiment of an anchor body  20  which is designed to be inserted into the recess shown in  FIGS. 1 and 2  as is best illustrated in  FIG. 6 . The anchor body  20  has an open top  22 , an open bottom  24  and a generally cylindrical wall  26  which extends between the open top  22  and the open bottom  24 . The cylindrical wall  26  includes a central channel  28  which extends from the open top  22  to the open bottom  24 . The channel  28  defines an inner engagement surface  30 . The outside of the cylindrical wall  26  defines and outer engagement surface  32 . 
         [0055]    The embodiment shown in  FIGS. 3-6  also includes a pair of first orifices  34  which are axially aligned and extend through the cylindrical wall  26  between the inner engagement surface and the outer engagement surface. These first orifices  34  each provide an additional access pathway to the channel  28  of anchor  20 . The cylindrical wall  26  has a recess  36  which extends upwardly from each of the first orifices  34 . The fact that there are two such orifices  34  and two such recesses  36  is best illustrated in  FIG. 4 . The orifices  34  make it possible to pass suture material (not shown in  FIGS. 3-6 ) through the cylindrical wall  26 . Such suture material also extends up through the recesses  36  when the cylindrical suture anchor is positioned as shown in  FIG. 6 . The suture material may be formed into any suitable suture member. As used herein, “suture member” refers to any suture, any suture tape or other flexible, strong, elongate material which may be used interchangeably with either a traditional suture or suture tape. 
         [0056]    To make it easier to align and insert the anchor body  20  shown in  FIG. 3 , the bottom portion of the anchor body  20  has a tapered section  42 . Further, the top portion of anchor body  20  includes a flange  38  surrounding a narrowed projecting portion  40 . These are used to couple the anchor body  20  to an insertion tool  60  as illustrated in  FIGS. 21 and 22  and discussed in greater detail below. 
         [0057]    As illustrated in  FIG. 6 , the anchor body  20  is intended to be inserted within the cylindrical hole  4  such that the bone core  8  extends up through the channel  28  of suture anchor  20 . A portion of the bone core  8  is visible through the first orifice  34 . 
         [0058]      FIG. 6  shows the open bottom  24  of the suture anchor  20  resting on the base  6  of the cylindrical hole  4 . The open top  22  of the anchor body  20  is substantially flush with the exposed surface  2  of the bone  1 . Those of ordinary skill in the art will recognize that in some applications it may be desirable to recess the anchor body  20  below the exposed surface  2  of the bone. In other surgical applications, it may be desirable to leave a portion of the suture anchor  20  exposed. 
         [0059]    While sutures are not shown in  FIGS. 3-6 , one skilled in the art should understand that these sutures would pass through the aligned orifices  34  on the front and back of the anchor body  20  and then extend up through the recesses  36  which extend upwardly from these orifices  34  on the front and back of the anchor body  20 . The sutures can then be used to attach a ligament, tendon or other structure to the bone. The anchor body  20  shown in  FIGS. 3-6  may be preloaded with sutures to form the suture anchor. 
         [0060]      FIGS. 7 and 8  show an alternative embodiment similar to that shown in  FIGS. 7 and 8 . In the embodiment of  FIGS. 7 and 8 , the first orifice has been replaced an orifice  44  closer to the bottom of the anchor body  20 . In  FIG. 8 , the bone core is visible through this orifice  44 . While only one such orifice  44  is shown in the drawings, one skilled in the art will recognize that additional orifices may be provided. As will be discussed in greater detail below with reference to  FIGS. 23 and 24 , the arrangement shown in  FIGS. 7 and 8  is well suited for a knotless suture application. 
         [0061]      FIGS. 9-12  show an embodiment of an anchor body  20  similar to that shown in  FIGS. 3-6 . In the embodiment of  FIGS. 9-12 , ridges  50  extend from the outer engagement surface of the cylindrical wall  26  of anchor body  20 . These ridges  50  assist in binding the anchor body  20  to the bone. As best illustrated in  FIG. 12 , the ridges  50  engage the outer bone surface  12  to lock the anchor body  20  in place after it has been inserted into the cylindrical hole  4  and pushed down against the base  6  of the cylindrical hole  4 . When the embodiment of  FIGS. 9-12  is employed, the anchor body  20  is impacted into position such that the bone core  8  extends through the open bottom  24  and channel  28 . A portion of the bone core  8  is visible through orifice  34  in  FIG. 12 . A similar embodiment to that shown in  FIGS. 9 and 12  is shown in  FIG. 26 . In this and other embodiments the anchor body  20  may be provided with vents  35  through the wall of the anchor body  20  to permit vascular flow and bone growth between inner bone surface  10  and the outer bone surface  12 , i.e., the bone of the bone core  8  along the internal engagement surface of the anchor body  20  and the bone against the external engagement surface of the anchor body  20 . Bone growth through these vents serves to further reinforce anchor fixation to bone, preventing dislodgement. 
         [0062]      FIGS. 13 and 14  show an embodiment similar to that shown in  FIGS. 7 and 8 . As illustrated in  FIGS. 13 and 14 , ridges  50  have added to the outer engagement surface  32  of the cylindrical wall  26 . These ridges  50  are adapted to engage the outer bone surface  12  to secure the anchor body  20  within the cylindrical hole  4  formed in the bone  1  as shown in  FIG. 14 . 
         [0063]    In lieu of ridges  50  of the embodiments illustrated in  FIGS. 9-14 , the cylindrical wall  26  of the anchor body  20  may be provided with exterior threads. Such threads  52  are illustrated in the embodiments shown in  FIGS. 15-18 . The threads  52  are self-tapping such that when the anchor body  20  is screwed into the end of the cylindrical hole  34 , mating threads are formed in the bone itself which cooperate with the threads  52  to help capture the anchor body  20  in place within the cylindrical hole  4 . In the embodiment shown in  FIG. 18 , the projecting portion  40  has a tool receiving notch  41  discussed below. 
         [0064]      FIG. 19  shows an additional feature of the anchor body  20  which may be employed with any of the previously described embodiments. Specifically, the cylindrical wall  26  may be provided with both exterior ridges or threads  50 / 52  and interior threads or ridges  54 . When two sets of threads are employed, both sets of threads are self-tapping. As such, when the anchor body  20  is screwed into the cylindrical hole  4 , mating threads are formed in both the outer bone surface  12  and the inner bone surface  10  (i.e., the exterior of the bone core  8  to provide even more holding power. Of course, one skilled in the art should understand that in lieu of such interior and exterior threads, interior and exterior ridges may be provided to achieve similar holding power. 
         [0065]    While anchor bodies of the type described above may be manufactured and packaged separately, it is also possible to provide to such anchor bodies as part of a kit. The kit may also include the suture material, a tool for forming the cylindrical hole  4  in the bone  1  while leaving the bone core  8  in place at the anchor point, and an insertion tool. The tool forming the hole can be a punch or drill designed to form the cylindrical hole  4  while leaving the bone core  8  in place. 
         [0066]    An insertion tool is illustrated in  FIGS. 22-24 . The insertion tool  60  includes a handle section extending from a first end of an engagement section  64 . The second end  68  of the engagement section  64  is open and a second channel  66  extends from this open end to a passageway  74 . Passageway  74  extends from the channel  66  through the outer surface  72 . The open end  68  of the tool also has an engagement surface  70 . 
         [0067]    As illustrated in  FIGS. 22 through 24 , the opening in the end  68  of the engagement section  64  is large enough to receive the projection  40  of the anchor body  20 . Further, end  68  of the insertion tool  60  includes an engagement surface  70  which engages the flange  38  of the suture anchor when the handle is coupled to the anchor body  20 . An impaction force can then be applied using a mallet (not shown) via the handle  62  to drive the anchor body  20  into the cylindrical hole  4  in the bone. One skilled in the art will also recognize that the channel  66  of the engagement section  64  of the handle  60  and the projection  40  of the suture anchor  20  may be keyed such that rotation of the handle serves to rotate the suture anchor  20 . Such keying will, of course, be advantageous and necessary when threads  52  and/or  54  are provided as opposed to ridges  50 . A slightly modified insertion tool is illustrated in  FIG. 21  and discussed below. 
         [0068]    Again, the anchor body  20  shown in  FIGS. 22 through 24  will typically be preloaded with suture material.  FIG. 24  shows an anchor  20  which will typically be used to achieve knotless attachment of the suture material. In  FIG. 23  the suture material is labeled  80 . The suture material  80  includes a loop  81 . The suture material  80  extends from both sides of this loop  81  such that the ends  82  and  83  of suture material  80  may be passed through the orifice  44  and channel  28  of the anchor body  20  and then out through the open top  22  of the anchor body  20 . The ends  82  and  83  of the suture material  80  are then fed through (i) the opening in the end  68  of the insertion tool  60 , (ii) the second channel  66  of the insertion tool  60  and back out through the passageway  74  of insertion tool  60 . The free ends  82  and  83  of the suture material  80  may then be used to attach a ligament, tendon. 
         [0069]      FIG. 25  is provided to show how the suture material  80  is held in place. As illustrated, after the insertion tool  60  has been used to force the anchor body  20  into the cylindrical hole  4 , the loop  81  of the suture material resides and is pinched between the outer bone surface  12  formed by creating the cylindrical hole  4  in the bone  1  and the outer engagement surface  32  of the cylindrical wall  26  of the anchor body  20 . The suture material extends from the loop  81  through the orifice  44  and into the channel  28  of the anchor body  20 . Specifically, the suture material  80  extends and is pinched between the inner bone surface  10  (i.e., the surface of the bone core  8 ) and the inner wall  30  of the anchor body  20 . The suture material  80  then extends out of the open top  22  of the anchor body  20 . The free ends  82  and  83  may then be used to attach ligaments, tendons or the like to the bone, and because the portion of the suture material  80  residing within the cylindrical hole and suture anchor is so tightly pinched both between the outer bone surface  12  and the outer engagement surface  32  as well as between the inner bone surface  10  and the inner engagement surface  30 , the suture material  80  is firmly coupled in place by the anchor body  20  and the bone. 
         [0070]    The anchor body embodiment of  FIG. 18  will now be described in further detail. Anchor body  20  has, at least, external threads  52 . This anchor body is, again, hollow and adapted to fit in the cylindrical hole  4  and surround a bone core  8 . The external threads  50  are adapted to engage the outer bone surface  12 . If inner threads such as those illustrated in  FIG. 19  are provided, the inner threads  54  are adapted to engage the inner bone surface  10  (i.e., the exterior of the bone core  8 ) to provide even more holding power. Located at the bottom of the anchor body  20  shown in  FIG. 18  is a cylindrical extension  92  projecting distally from a flange  93 . Located at the proximal end of the bone anchor  20  is a proximal projection  40  having a slot  41  extending distally from the proximal end of the anchor body  20 . 
         [0071]    Also shown in  FIG. 18  is a short, hollow, cylindrical cap  94  which may be loaded with suture material  80  comprising one or more suture members and positioned at the distal tip of the anchor body  20 . More specifically, cap  24  has a hollow cylindrical wall  96  adapted to receive cylindrical extension  92 . The cylindrical wall  96  has a proximal end  97  which engages the flange  93  when the cap  94  is coupled to the anchor body  20 . The cap  94  also has a pair of outwardly extending wings  98  adapted to engage the outer bone surface  12 . Like the anchor body  20 , the cap is also adapted to surround the bone core  8 . An orifice  100  extends through the wall  96  of the cap  94  to permit suture material  80  to be passed through the wall  96  similar to the manner shown in  FIGS. 24 and 25 . Prior to implantation of the anchor body  20  in the bone  1 , the cap  94  is mated to the anchor body  20 . The anchor body  20  and cap  94  are held together by a firm friction fit between cylindrical extension  92  and cylindrical wall  96 . The assemble is then aligned with the cylindrical hole  4  and bone core  8  and pushed into the cylindrical hole  4  until the threads  52  reach the cylindrical hole  4 . The anchor body  20  is then screwed into place. As the anchor body is screwed into place, the cap is driven into and secured in the bone at the distal end of the anchor body  20 . Furthermore, in some embodiments the cap permits the flange of the cylindrical extension  92  of anchor body  20  to rotate freely within the cap  94 , without necessarily generation rotation of the cap itself. Thus, the cap  94  is driven deeper into the prepared recess without rotating. 
         [0072]    Various tools may be used to implant the anchor body  20  and cap  94  shown in  FIG. 18 . One such tool  60  is shown in  FIG. 21 . This tool is nearly identical to the impaction tool  60  shown in  FIGS. 22 through 24 . The sole difference is that a plate  69  has been added which extends across the second end  68  of the engagement section. This plate is adapted to be received within the slot  41  of the anchor body  20  shown in  FIG. 18 . This allows the tool first to be used to impact the anchor body  20  and cap  94  into the cylindrical hole  4  until the threads  52  engage the cylindrical hole, and then to be used to rotate the anchor body  20  to drive the anchor body  20  and cap  94  into their final implanted position within the cylindrical hole  4  and surrounding the bone core  8 . Other tools, such as an ordinary screw driver, could also be fitted in the slot  41  to perform these functions. However, the tool  60  illustrated in  FIG. 21  offers better control. Also, the cylindrical wall  66  is adapted to frictionally engage the projection  40  to temporarily hold the tool  60  to the anchor body  20  in a similar manner to the way the cap  94  is frictionally held to the cylindrical extension  92 . Thus, during implantation, the surgeon is able to hold, with one hand and in assembled relation, the entire assembly comprising the anchor body  20 , cap  94 , suture material  80  and tool  60 . 
         [0073]    Implantation of the anchor body  20  may also be simplified by providing the distal tip of the anchor body (e.g.,  24  in  FIG. 3 ) or a distal cap (e.g.,  94  in  FIG. 18 ) associated therewith which is reinforced with or formed of a sharpened ring of metal alloy that permits the anchor body (or cap) to form its own recess as it is being impacted into the recipient bone. This eliminates the need for prior formation of the recess. In such embodiments, the anchor body would be considered “self-punching” as it would form its own recess. 
         [0074]    The foregoing description is intended to explain the various features and advantages, but is not intended to be limiting. The scope of the invention is defined by the following claims which are also intended to cover a reasonable range of equivalents.