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 . 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 . fig1 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 fig2 . 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 . fig3 - 6 illustrate a first embodiment of an anchor body 20 which is designed to be inserted into the recess shown in fig1 and 2 as is best illustrated in fig6 . 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 . the embodiment shown in fig3 - 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 fig4 . the orifices 34 make it possible to pass suture material ( not shown in fig3 - 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 fig6 . 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 . to make it easier to align and insert the anchor body 20 shown in fig3 , 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 fig2 and 22 and discussed in greater detail below . as illustrated in fig6 , 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 . fig6 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 . while sutures are not shown in fig3 - 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 fig3 - 6 may be preloaded with sutures to form the suture anchor . fig7 and 8 show an alternative embodiment similar to that shown in fig7 and 8 . in the embodiment of fig7 and 8 , the first orifice has been replaced an orifice 44 closer to the bottom of the anchor body 20 . in fig8 , 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 fig2 and 24 , the arrangement shown in fig7 and 8 is well suited for a knotless suture application . fig9 - 12 show an embodiment of an anchor body 20 similar to that shown in fig3 - 6 . in the embodiment of fig9 - 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 fig1 , 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 fig9 - 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 fig1 . a similar embodiment to that shown in fig9 and 12 is shown in fig2 . 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 . fig1 and 14 show an embodiment similar to that shown in fig7 and 8 . as illustrated in fig1 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 fig1 . in lieu of ridges 50 of the embodiments illustrated in fig9 - 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 fig1 - 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 fig1 , the projecting portion 40 has a tool receiving notch 41 discussed below . fig1 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 . 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 . an insertion tool is illustrated in fig2 - 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 . as illustrated in fig2 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 fig2 and discussed below . again , the anchor body 20 shown in fig2 through 24 will typically be preloaded with suture material . fig2 shows an anchor 20 which will typically be used to achieve knotless attachment of the suture material . in fig2 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 . fig2 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 . the anchor body embodiment of fig1 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 fig1 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 fig1 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 . also shown in fig1 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 fig2 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 . various tools may be used to implant the anchor body 20 and cap 94 shown in fig1 . one such tool 60 is shown in fig2 . this tool is nearly identical to the impaction tool 60 shown in fig2 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 fig1 . 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 fig2 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 . implantation of the anchor body 20 may also be simplified by providing the distal tip of the anchor body ( e . g ., 24 in fig3 ) or a distal cap ( e . g ., 94 in fig1 ) 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 . 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 .
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 .