Abstract:
Anchoring a tendon to a bone is achieved by forming a tunnel in the bone and employing a self-anchoring integrally formed anchor body. A portion of the tendon is wrapped around the anchor body and then the anchor body is driven into the tunnel to attach the tendon to the bone.

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 The present invention relates to surgical implants used in orthopedic surgery. More specifically, this invention relates to devices used to attach a tendon to a bone. 
         [0004]    II. Related Art 
         [0005]    A variety of different implantable devices have been employed to achieve tendon fixation to bone without the necessity of sutures or other secondary fixation intermediaries. The devices are generally used in the context of tendon repair or “tenodesis” surgery. In the case of the former, the device is used to reattach a tendon that has avulsed from its attachment. In the latter, the device is used to attach or fix a tendon in a given location that achieves a specific therapeutic end for the patient. For example, in the case of a “biceps tenodesis” procedure, most commonly the long head of the biceps tendon is fixed to bone in either a proximal location within the bicipital groove or in a more distal location in order to reduce or eliminate pain coming from a damaged portion of the tendon. 
         [0006]    U.S. Pat. No 5,632,748 granted May 27, 1997 to Beck, Jr. et al discloses several different anchor devices. Each includes an anchor body and a separate threaded insertion member that is used either to wedge the anchor body against the wall of a tunnel formed in the bone, or to expand the anchor body against the wall of the tunnel. Implanting multiple parts in a confined area is inherently difficult, particularly when one must also employ tools to hold the anchor body in a position so the anchor body will not unduly pinch the tendon being anchored and, at the same time, tools to insert the insertion member into the tunnel adjacent the anchor body or into the anchor body itself. It is also difficult to achieve proper purchase of such parts in the tunnel to secure the tendon in place. 
         [0007]    U.S. Pat. No. 8,048,158 to Mays et al likewise shows anchor devices including a ligament engagement member disposed in a bone tunnel with the ligament alongside the engagement member, and a locking member also disposed in the tunnel and engaging the ligament engagement member to wedge the ligament engagement member and ligament against the wall of the bone tunnel. The devices shown in Hays et al suffer from the same deficiencies as those shown in the aforementioned Beck, Jr. et al patent. 
         [0008]    U.S. Pat. No. 8,512,805 to Baird discloses an anchor which also has two different pieces that are wedged against each other and the wall of a tunnel formed in the bone to secure a tendon in place. The Baird patent also discloses a tool for inserting the two implants which include a sharp tip inserted through the tendon to hold it in place as the two implants are pounded into the tunnel and wedged against each other. While this may assist in implanting the two pieces of the implant and holding the tendon in place, proper purchase and damage to the tendon remains an issue. 
       SUMMARY OF THE INVENTION 
       [0009]    Anchoring a tendon to a bone can be achieved by forming in the bone a tunnel having an opening and a circumferential wall and providing an integrally formed and self-anchoring anchor body. In one embodiments the anchor body has a first end and a second end. Extending between the two ends are a pair of opposing concave walls and a pair of opposing convex walls. The radii of curvature of the two opposing convex walls of the anchor body are such that they form two opposing arcs along a single circle. This design element permits a surgeon to drill or punch a single, circular socket (i.e., tunnel) for implantation of the anchor body. 
         [0010]    The first end of the anchor body comprises a flat engagement surface. The fiat engagement surface engages a surface of an impaction tool during implantation of the anchor body. The second end of the anchor body comprises a concave engagement surface having arches at the bottom of the opposing concave walls. This second end engages a tendon to be secured by the anchor body, permitting direct control of the tendon as well as a measure of fixation during the implantation process. These arches extend between the convex walls. 
         [0011]    The anchor body has two sets of ribs. The ribs of a first set project outwardly from each of the pair of opposing convex walls. These ribs are adapted to engage the circumferential wall of the tunnel formed in the bone such that their angles resist backing out of the device after implantation. The ribs of a second set project outwardly from each of the pair of opposing concave walls. These ribs are adapted to engage a tendon extending along these walls and their angles are such that they resist slippage of the given tendon against the body of the anchor. 
         [0012]    The anchor body may also be provided with a central channel, extending through the anchor body, open to the first and second. One or more connecting members spanning the central channel between the two concave walls may also be provided. Such a connecting member serves to increase the structural rigidity of the anchor body depending upon the material out of which the anchor is manufactured and to provide a post around which a suture may be tied. 
         [0013]    The overall length of the anchor body, as measured linearly from the first end to the second end, will vary depending on the anatomic location of use. For example, the implantation of the anchor body within the canal of the humerus will typically require a shorter anchor body than implantation within the proximal humerus. The diameter of the anchor body may vary for similar reasons. 
         [0014]    When the above-described anchor body is employed, the tendon to be joined (or “tenodesed”) to the hone is placed over the tunnel opening. The anchor body is then placed over the tendon and opening such that a portion of the tendon resides within the arches and engages the concave engagement surface. The anchor body is then inserted into the tunnel. As this occurs, portions of the tendon on opposing sides of the concave engagement surface are sandwiched between the circumferential wall of the tunnel and the two concave walls of the anchor body such that the ribs of the second set of ribs engage the tendon. At the same time, the ribs of the first set of ribs engage the circumferential wall of the tunnel to secure the anchor body and tendon to the bone. 
         [0015]    Some surgeons may find holding the tendon and anchor body in the proper orientation is most easily achieved by employing a piece of suture material that extends down through the central channel of the anchor body, around the tendon and then back up through the channel, This piece of suture material may be used to pull the tendon into the arches and into contact with the concave engagement surface. The device may be equipped with a wire loop (or loops) that extends through the central, hollow portion of the anchor that would facilitate passage of such a piece of suture material through the body of the anchor. The suture may also be used to retain, at least temporarily, the tendon in contact with the concave engagement surface to simplify the process of inserting the anchor body and tendon into the tunnel formed in the bone. If use of a suture is desired and the anchor body is provided with the aforementioned connecting member spanning the gap (i.e., central channel) between the two concave walls of the anchor body, the surgeon may tie the suture to the connecting member. Doing so may also provide additional fixation of the tendon to the anchor body and potentially provide a further impediment to tendon slippage during or after fixation of the tendon to the bone using the anchor body. 
         [0016]    An impaction tool having an elongate shaft, a flange and a tip may also be employed. The impaction tool is adapted to be coupled to the first end of the anchor body. Specifically, the tip is inserted into the channel until the flange engages the flat engagement surface. A mallet may then be used to pound on the shaft and drive the anchor body into the bone tunnel. The flange is designed to have a diameter larger than the opening of the bone tunnel fashioned to accept the anchor and tendon, providing a “positive stop” and preventing over-insertion of the anchor. When the suture material is employed as discussed above, the tolerances between the tip and channel and/or first engagement surface and flange may be such that sufficient pinching forces are applied to the suture material. to hold the suture material in place so that the tendon properly engages the concave engagement surface as the anchor body is inserted into the tunnel formed in the bone to couple the tendon to the bone. After insertion of the anchor body into the bone, the suture material may be extracted, or tied as described above and cut flush with the surface of the bone. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    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. 
           [0018]      FIG. 1  is a front view of the anchor body of  FIG. 1 , the rear view being a mirror image thereof; 
           [0019]      FIG. 2  is a side view of the anchor body of  FIG. 1 , the opposite side view being a mirror image thereof; 
           [0020]      FIG. 3  is a top view of the anchor body of  FIG. 1 ; 
           [0021]      FIG. 4  is a top view of an alternative embodiment; 
           [0022]      FIG. 5  is a perspective view of the anchor body of  FIG. 1  being used to join a tendon to a bone; 
           [0023]      FIG. 6  is a perspective view showing a piece of bone and a tendon; 
           [0024]      FIG. 7  is a perspective view of the bone and tendon of  FIG. 5  with a tunnel formed in the bone; 
           [0025]      FIG. 8  is a perspective view of the bone, tendon and tunnel of  FIG. 6  and the anchor body of  FIG. 1  partially inserted into the tunnel; 
           [0026]      FIG. 9  is a top view of the components of  FIG. 7  with the anchor body fully inserted into the bone; 
           [0027]      FIG. 10  illustrates a piece of suture material extending through the anchor body of  FIG. 1  and around a tendon; 
           [0028]      FIG. 11  illustrates an assembly comprising the components of  FIG. 9 , but with the tendon pulled tight against the anchor body; 
           [0029]      FIG. 12  is a side view of a first impaction tool intended for use with the anchor body of  FIG. 3 ; 
           [0030]      FIG. 13  is a perspective view of the impaction tool of  FIG. 12 ; 
           [0031]      FIG. 14  is a side view of a second impaction tool intended for use with the anchor body of  FIG. 4 ; 
           [0032]      FIG. 15  is a perspective view of the impaction tool of  FIG. 14 ; and 
           [0033]      FIG. 16  shows an impaction tool coupled to an anchor body. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    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. 
         [0035]      FIGS. 1-4  show an integrally formed anchor body  1  having a first end  2  and a second end  3 . Extending between the first end  2  and the second end  3  are a pair of opposing convex walls  5  and  6  and a pair of opposing concave walls  7  and  8 . The radii of curvature of convex walls  5  and  6  are such that walls  5  and  6  form two opposing arcs of a single circle. 
         [0036]    Projecting outwardly from each of the convex walls  5  and  6  are a first set of ribs  10 . Eight such ribs  10  are illustrated on each of the convex walls  5  and  6 . A fewer or larger number of ribs may be provided. Likewise, the shapes of the ribs  10  may be altered. Projecting outwardly from each of the concave walls  7  and  8  are a second set of ribs  12 . Three such ribs  12  are illustrated on each of the concave side walls  7  and  8 . Again, the number and shape of the ribs  12  may be varied. 
         [0037]    The first end  2  comprises a flat engagement surface  16 . The second end  3  has a concave engagement surface  20 . More specifically, the bottom of each concave wall  7  and  8  forms an arch  22  that extends between the bottoms of the two convex walls  5  and  6 . A channel  24  extends through the center of anchor body  1 . Channel  24  is surrounded by the walls  5 ,  6 ,  7  and  8  and is open to both the first end  2  and the second end  3 . As illustrated in  FIG. 4 , this channel  24  may include one or more connecting members  25  dividing channel  24  in two. These connecting members  25  span the distance between the two concave walls  7  and  8  These connecting members  25  are integral with the remainder of anchor body  1 . The connecting members  25  may be molded with the other portions of the anchor body  1  or the two ends of the connecting members  25  may be bonded or otherwise permanently attached to the inside surfaces of the concave walls  7  and  8 . 
         [0038]      FIGS. 5-9  illustrate how the anchor body is employed to couple a tendon  50  to a bone  60 . First, and as shown in  FIG. 6 , the tendon  50  is placed proximate to a bone  60  to determine the desired attachment point. Next, and as shown in  FIG. 7 , a tunnel  70  is formed in the bone  60  at the attachment point. The tunnel  70  has an opening  72  and a circumferential wall  74 . As shown in  FIG. 8 , after tunnel  70  has been formed, a portion of the tendon  50  is placed over the open end  72  of tunnel  70 . The tunnel  70  may be a single, circular socket drilled or punched into the bone  60  if the convex walls  5  and  6  form two opposing arcs of a single circle, as described above. An anchor body  1  is then placed so that the second end  3  is in contact with the tendon  50 . More specifically, the tendon  50  extends through the area beneath arches  22  between the bottoms of convex walls  5  and  6  and is in contact with the concave engagement surface  20 . Finally, the anchor body  1  is driven into the tunnel  70  to reach the position shown in  FIG. 9  and  FIG. 5 . 
         [0039]      FIG. 5  illustrates how the anchor body  1  and the circumferential wall  74  of tunnel  70  cooperate to anchor the tendon  50  to the bone  60 . As shown, tendon  50  extends down along concave wall  7 , under the concave engagement surface  20  (i.e., through the arches  22  at the bottom of the concave walls  7  and  8 ) and up along the concave wall  8 . As such, tendon  50  is sandwiched between the circumferential wall  74  (and. bottom) of tunnel.  70  and the two concave walls  7  and  8 . The ribs  12  extending outwardly from the concave walls  7  and  8  engage the tendon  50  to hold the tendon  50  in place and prevent the tendon  50  from pulling out of the tunnel  70 . The ribs  10  projecting from the convex walls  5  and  6  engage the circumferential wall  74  of the tunnel  70  to hold the anchor body  1  in place. As such, the integrally formed anchor body  1  is also self-anchoring since, once the anchor body  1  has been inserted into the tunnel  20 , no other mechanical device, bonding agent or other mechanism is required to hold the anchor body  1  in place. 
         [0040]    As noted above, the anchor body  1  may be provided with a central channel  24  open to the first end  2  and the second end  3 .  FIGS. 10-16  are provided to illustrate the functionality provided by such a channel  24 . 
         [0041]      FIG. 10  shows a length of suture material  100  extending around a tendon  50 . The two ends  102  and  104  of the suture material  100  have been fed through the central channel  24  of anchor body  1 . Pulling on the free ends  102  and  104  of suture material  100  while holding he anchor body  1  serves to draw the tendon toward the anchor body  1 . in  FIG. 11 , the suture material  100  is being used to secure the tendon into contact with the concave engagement surface  20 . More specifically, the tendon  50  is in contact with arches  22  and is between the bottoms of the convex walls  5  and  6 . 
         [0042]    When the embodiment illustrated in  FIG. 4  is employed, the connecting member(s)  25  not only provide internal support so the anchor body  1  does not collapse during insertion, thereby improving the compressive force directing the tendon against bone, the connecting member(s)  25  also provide a post over which the suture  100  can be tied to provide additional fixation of the tendon  50  to the anchor body  1  to help impede tendon slippage at least during implantation and potentially also after implantation. 
         [0043]    As shown in  FIGS. 12 through 16 , an impaction tool  120  may be provided.  FIGS. 12 and 13  show an impaction tool  120  which is well suited for implantation of the anchor body shown in  FIG. 3 .  FIGS. 14 and 15  show an impaction tool  120  well suited for implanting an anchor body  1  having inner connecting members  25 , as shown. in  FIG. 4 . Many features are shared by the impaction tool shown in  FIGS. 12 and 13  and the impaction tool shown in  FIGS. 14 and 15 . Each comprises an elongate shaft  122  having a first end  124 . A flange  126  is adjacent a second end of shaft  122 . Projecting from the flange  126  approximately 180° from the shaft  122  is a tip. The embodiment of  FIGS. 12 and 13  has a tip comprising a single member  128 . The size and shape of the tip  128  are adapted to permit the tip  128  to be inserted into the channel  24 , shown in  FIG. 3 , until the flange  126  contacts the flat engagement surface  16  of the first end  2  of anchor body  1 . The fit between the tip  128  and the surfaces defining channel  24  is intended to be snug. As such, there is enough pinching force exerted between the tip  128  and the surfaces defining channel  24  to hold the suture material  100  and the tendon in engagement with the concave engagement surface  20 , as shown in  FIG. 11 . The embodiment of  FIGS. 14 and 15  differs only in that the tip has two members  130  and  132 . These members  130  and  132  reside on opposite sides of connecting member(s)  25  when the tool and anchor member are coupled together. 
         [0044]    From the foregoing, one skilled in the art will appreciate no more than two hands are required to (i) wrap the suture material  100  around the tendon  50  and pass the free ends  102  and  104  of the suture material  100  through the channel  24  of anchor body  1 ; (ii) draw and then hold the tendon  50  in proper engagement with the concave engagement surface  20 ; (iii) insert the tip ( 128  in  FIGS. 12 and 13 and 130 / 132  in  FIGS. 14 and 15 ) of the impaction tool  120  into the channel  24  of anchor body  1  until the flange  126  reaches the flat engagement surface  16  to thereby temporarily secure the tendon  50 , anchor body  1  and tool  120  together; (iv) use the tool  120  to insert the tendon  50  and second end  3  of anchor body  1  into the tunnel  70 ; and (v) tap on the end  124  of the tool  120  with a mallet (not shown) to drive the anchor body and attached tendon  50  into the tunnel  70  to couple the tendon  50  to the bone  60 . The procedure is then completed by retracting the tool  120  from the channel  24  (and the surgical site) and trimming the suture material. As such, the disclosed embodiment may be employed to secure a tendon to a bone either in traditional open fashion, or arthroscopically. 
         [0045]    From the foregoing, one of ordinary skill should also recognize that various modifications may be made without deviating from the invention. For example, the anchor body may be made from any number of biocompatible materials. Some examples include poly ether ether ketone (PEEK) and similar plastics, poly-L-lactic acid (PLLA)and similar bioabsorbable or biocomposite materials, titanium and various stainless steel alloys. Further, various materials could be employed instead of suture material to draw and hold the tendon in contact with the anchor body. 
         [0046]    For example, a strap of shape memory material such as nitinol could be extended between the bottoms of the two convex walls around the tendon. The nitinol material, as it is warmed from room temperature (about 68° F.) its body temperature (about 98.6° F.) would reach its transition temperature and then change shape to draw the tendon into contact with the concave engagement surface. This would eliminate the need for the channel. Further, the tool could be designed with a socket to receive the first end of the anchor body rather than a tip inserted into the anchor body. As previously noted, the number of ribs extending from the concave and convex walls may be altered. The shape of the ribs may also be altered. The dimensions of the concave and convex walls and concave recess may be altered to accommodate tendons and bones of differing thicknesses. The dimensions of the bone anchor  1  may also be adapted for use at different implantation sites. 
         [0047]    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.