Abstract:
A suture anchor that allows a surgeon to securely and efficiently suture soft tissue to bone without knotting the suture, comprising a locking body through which a suture is passed, and an anchor collar, which, when positioned over the suture passing through the locking body, secures the suture.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to the field of suture anchors used to attach soft tissue to bone. More particularly, this invention relates to a knotless suture anchor.  
         BACKGROUND OF THE INVENTION  
         [0002]    Often, doctors have to attach various soft tissues, such as tendons and ligaments, to hard tissue, such as bone. To provide an alternative to suturing the soft tissue directly through tunnels in the bone, suture anchors have been developed to aid in this attachment. Generally, the doctor will attach such soft tissue to bone by suturing the soft tissue to a suture anchor that has been placed in the bone. During this suturing procedure, the surgeon must pass a suture through the tissue to be repaired, attach it to the suture anchor, and knot the suture so that the tissue is securely fastened to the suture anchor. Knotting a suture, particularly when operating within a joint arthroscopically, requires great skill on the part of the surgeon and can be extremely time consuming. Further, knots in sutures can be bulky, and cause irritation or damage within a joint. Thus, there is a desire to develop a suture anchor that may effectively, efficiently, and securely attach soft tissue to bone without requiring the surgeon to knot the suture.  
           [0003]    One attempt to develop a knotless suture anchor resulted in a suture anchor that has a loop of suture thread pre-tied to the suture anchor. In order to affix soft tissue to bone using this suture anchor, the surgeon must pass the loop through the soft tissue and then pass the suture anchor back through the loop. This technique is difficult to perform, particularly arthroscopically, and also is time consuming.  
           [0004]    In addition, suture anchors that have loops of suture already attached to them suffer from several other drawbacks. For instance, the surgeon must use the type and length of suture that comes pre-attached to the suture anchor. However, different applications may require different types and lengths of suture. It is preferable for a surgeon to be able to use whatever suture he feels is appropriate for a particular application.  
           [0005]    Further, the techniques with which the surgeon may suture the soft tissue are limited when using a loop of suture thread of predetermined length that is already attached to the suture anchor. It is more preferable to give the surgeon the freedom to attach the suture to the soft tissue in whichever manner he desires, depending upon the particular application.  
           [0006]    Thus, there is a need for a suture anchor that may be used efficiently and easily, without requiring the surgeon to tie a knot, yet allowing the surgeon maximum flexibility in the manner in which he attaches the suture to the soft tissue.  
         SUMMARY OF THE INVENTION  
         [0007]    In a preferred embodiment, the suture anchor of the present invention comprises a locking body containing an opening, or eyelet, for receiving suture thread, and a collar that is capable of moving along the locking body. At the distal end of the locking body there is a head for securing the locking body into the bone. The head allows the locking body to be inserted into the bone, put prevents the body from easily being pulled out of the bone. Similarly, the collar is designed so that it may be inserted into bone, but may not easily be pulled out of the bone. The suture anchor may be made of biostable or biodegradable material. In a preferred embodiment, the suture anchor is made of strong, self-reinforced, bioabsorbable polymer.  
           [0008]    In an embodiment of the present invention, a suture anchor is provided, comprising a locking body including a shaft, an eyelet configured to receive one or more suture threads, and at least one protuberance for securing the central anchoring post in bone and a collar movably engaged with the central anchoring post, the collar having a hole there through and having an exterior surface comprising at least one protuberance for securing the collar in bone, where the collar is configured to secure one or more suture threads between the collar and the locking body.  
           [0009]    Another embodiment of the present invention provides a method for attaching tissue to bone. The method includes, providing a suture anchor as described above, attaching suture thread to the tissue, positioning the ends of the suture through the eyelet, with the collar located distally to the eyelet, inserting the suture anchor into a pre-drilled hole in the bone while keeping the collar positioned distally to the eyelet, positioning the tissue by applying force to the ends of the suture, and further inserting the locking body into the hole in the bone so that the collar is located proximally to the eyelet, with the suture threads secured between the collar and the central anchoring post. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 shows a perspective view of an embodiment of the suture anchor of the present invention, including the locking body and collar.  
         [0011]    [0011]FIGS. 2 a - 2   c  show perspective views of an embodiment of the present invention including the locking body and collar of a suture anchor.  
         [0012]    [0012]FIG. 3 shows a perspective view of an embodiment of the suture anchor of the present invention and an installation instrument for inserting the suture anchor.  
         [0013]    [0013]FIG. 4 shows a cross section view of an embodiment of the present invention including an initial configuration of the locking body, collar, and a suture.  
         [0014]    [0014]FIG. 5 shows a cross section view of an embodiment of the present invention including an final configuration of the locking body, collar, and a suture.  
         [0015]    [0015]FIG. 6 shows another embodiment of the present invention with two sutures threaded through the eyelet of the locking body.  
         [0016]    [0016]FIG. 7 shows a perspective view of an embodiment of the present invention including the installation instrument, suture anchor and collar.  
         [0017]    [0017]FIG. 8 shows an enlarged view of FIG. 7.  
         [0018]    [0018]FIG. 9 shows a perspective view of an embodiment of the suture anchor about to be inserted into bone at a repair site.  
         [0019]    [0019]FIG. 10 shows a cross-sectional view of an embodiment of the suture anchor of the present invention after being initially inserted into bone at a repair site.  
         [0020]    [0020]FIG. 11 shows a perspective view of the proximal end of the installation instrument.  
         [0021]    [0021]FIG. 12 shows a cross-sectional view of an embodiment of the suture anchor of the present invention after the locking body has been pushed further into the bone.  
         [0022]    [0022]FIG. 13 shows a cross-sectional view of an embodiment of the suture anchor of the present invention after the locking body has been pushed further into the bone.  
         [0023]    [0023]FIG. 14 shows a cross sectional view of an embodiment of the suture anchor of the present invention after insertion of the suture anchor has been completed.  
         [0024]    [0024]FIG. 15 shows a perspective view of another embodiment of the suture anchor of the present invention in an initial configuration, having a anchor collar including screw threads.  
         [0025]    [0025]FIG. 16 shows another perspective view of the suture anchor of claim  15 .  
         [0026]    [0026]FIG. 17 shows a cross sectional view of the suture anchor of FIGS. 15 and 16.  
         [0027]    [0027]FIG. 18 shows a perspective view of the suture anchor of FIG. 15 in a final configuration.  
         [0028]    [0028]FIG. 19 shows a cross sectional view of FIG. 18.  
         [0029]    [0029]FIG. 20 shows a perspective view of the suture anchor of FIG. 15 attached to an installation tool.  
         [0030]    [0030]FIG. 21 shows another perspective view of FIG. 20.  
         [0031]    [0031]FIG. 22 shows a perspective view of the suture anchor of FIG. 18 disengaged from an installation tool. 
     
    
     DETAILED DESCRIPTION  
       [0032]    The present invention provides a suture anchor that allows a surgeon to securely suture soft tissue to bone without having to knot the suture. FIGS. 1 and 2 a - c  show preferred embodiments of the present invention. In these Figures, the suture anchor  100  of the present invention comprises a locking body  75  and an anchor collar  5 . The locking body  75  includes a central anchoring post  1  and distal head  2 . The anchor collar  5  is designed so that it may move relative to the locking body  75 . In a preferred embodiment, the anchoring collar  5  slides over the locking body  75 , which acts as a locking mechanism after insertion.  
         [0033]    The distal head  2  of locking body  75  is designed so that the locking body  75  may be inserted into bone, but may not easily be pulled out of the bone. The distal head  2  of the suture anchor  100  has a wedge shape, however other shapes may be used, provided that they do not allow the locking body  75  to be easily pulled out of bone after insertion. For example, distal head  2  may have ridges, protrusions, spikes, scales, or screw threads.  
         [0034]    The locking body  75  also includes an eyelet  3  for receiving suture thread. The eyelet  3  may be designed so as to receive one or more suture threads. This allows the soft tissue to be more securely fastened to the bone, and reduces the likelihood of suture wear or breakage, which may result in an ineffective repair.  
         [0035]    In a preferred embodiment, the locking body  75  may also comprise one or more indentations  4  located proximal to the eyelet  3  for receiving suture thread. The indentations  4  provide a guide for the suture thread, thereby reducing the movement of the suture during insertion of the suture anchor  100 . Further, the indentations  4  allow the suture collar  5  to more easily pass over the suture that is threaded through eyelet  3 , and more gradually engage the suture, thereby reducing the risk of suture wear or breakage, which may result in an ineffective repair.  
         [0036]    The locking body  75  may also comprise means  3   a  for preventing the anchor collar  5  from being separated from the proximal end of the locking body  75 . In a preferred embodiment, these means  3   a  are a section of the locking body  75 , which at its proximal end is wider in cross section than the inner diameter  14  of the anchor collar  5 , thereby locking the anchor collar  5  after insertion.  
         [0037]    The anchor collar  5  is designed to be able to be pushed in the distal direction into bone, but not easily pulled out of the bone. The outer surface of the anchor collar  5  has a wedge shape, however other shapes may be used, provided that they do not allow the anchor collar  5  to be easily pulled out of bone after insertion. For example, the collar may include ridges, spikes, scales, or the like.  
         [0038]    The anchor collar  5  has an initial diameter  0  at its proximal end as shown in FIGS. 2 a  and  2   b . In a preferred embodiment, the initial diameter θ is equal to or greater than 4 mm. This diameter will change upon final installation of the suture anchor  100 .  
         [0039]    The suture anchor may be constructed of biostable or biodegradable materials that are known to those of skill in the art. Table 1 includes a number of these materials.  
                         TABLE 1                       Biodegradable Polymers                                    Polyglycolide (PGA)Glycolide copolymers           Glycolide/lactide copolymers (PGA/PLA)           Glycolide/trimethylene carbonate copolymers (PGA/TMC)           Stereoisomers and copolymers of PLA           Poly-L-lactide (PLLA)           Poly-D-lactide (PDLA)           Poly-DL-lactide (PDLLA)           L-lactide/DL-lactide copolymersL-lactide/D-lactide copolymers           Copolymers of PLA           Lactide/tetramethylene glycolide copolymers           Lactide/trimethylene carbonate copolymers           Lactide/δ-valerolactone copolymers           Lactide/ε-caprolactone copolymers           Polydepsipeptides (glycine-DL-lactide copolymer)           PLA/ethylene oxide copolymers           Asymmetrically 3,6-substituted poly-1,4-dioxane-2,4-diones           Poly-β-hydroxybutyrate (PHBA)           PHBA/β-hydroxyvalerate copolymers (PHBA/PHVA)           Poly-β-hydoxypropionate (PHPA)           Poly-β-dioxanone (PDS)           Poly-δ-valerolactone           Poly-ε-caprolactone           Methylmethacrylate-N-vinylpyrrolidone copolymers           Polyesteramides           Polyesters of oxalic acid           Polydihydropyranes           Polyalkyl-2-cyanoacrylates           Polyurethanes (PU)           Polyvinyl alcohol (PVA)           Polypeptides           Poly-β-maleic acid (PMLA)           Poly-β-alkanoic acids           Polyethylene oxide (PEO)           Chitin polymers                      
 
         [0040]    In a preferred embodiment, the suture anchor may be constructed of self-reinforced biodegradable polymer, such as is disclosed in U.S. Pat. Nos. 6,406,498 and 4,968,317, which is hereby incorporated by reference. In another preferred embodiment, the locking body  1  and the anchor collar  5  are formed from different materials. For example, the locking body  1  may be constructed from self-reinforced biodegradable polymer and the anchor collar  5  may be formed from non self-reinforced biodegradable polymer.  
         [0041]    [0041]FIG. 3 shows that the anchor collar  5  may be positioned distally on the locking body  75  with respect to the eyelet  3 . FIG. 3 also shows a preferred embodiment of an installation tool  50  used to install the suture anchor  100 . The installation tool  50  comprises a cannula  7 , an anchor collar holder  6 , and a push rod  35  (not shown). Anchor collar holder  6  is designed to hold anchor collar  5  while push rod  35  pushes the locking body  75  into bone. The anchor collar holder  6  has a central indentation for receiving the proximal end of the locking body  75 . The distal end of the anchor collar holder  6  contacts the proximal end of the anchor collar  5 . When force is applied to the push rod  6 , both the anchor collar  5  and the locking body  75  may be pushed into bone. In a preferred embodiment, the anchor collar holder  6  may have a gap  8  for allowing a suture to more freely pass through the eyelet  3 . Likewise, the cannula  7  may have a gap  16  for allowing a suture to more freely pass through the eyelet  3 . The insertion tool  50  of FIG. 3 allows the suture anchor  100  to be easily and quickly inserted into a bone in an arthroscopic procedure.  
         [0042]    [0042]FIGS. 4 and 5 show cross sectional views of suture anchor  100  with a suture  11  threaded there through. In FIG. 4, anchor collar  5  is substantially proximal to suture  11 . This formation is the initial configuration prior to deployment or insertion of the suture anchor  100  into bone. Suture anchor collar  5  has a diameter of θ initially. FIG. 5 shows the anchor collar  11  in a substantially distal relationship with suture  11 , which is the configuration after insertion and deployment of the suture anchor  100  into bone. As may be seen, suture anchor collar  5  now has a diameter of θ+δ. This expansion of the suture anchor collar  5  occurs when the locking body  75  is pushed through the suture anchor collar  5  as the suture anchor  100  is inserted into bone. As may be seen in FIG. 5, suture  11  is guided along the sides of locking body  75  and held taunt by anchor collar  5 . In a preferred embodiment, the final length of the suture anchor  100 , following insertion may be equal to or less than 20 mm.  
         [0043]    [0043]FIG. 6 shows a perspective view of suture anchor  100  attached to insertion tool  50 . In FIG. 6, two sutures are seen threaded through suture anchor  100 . The configuration shown in FIG. 6 is the initial configuration prior to insertion of the suture anchor  100  into bone.  
         [0044]    [0044]FIG. 7 shows a full view of the installation tool  50  with suture anchor  100  attached thereto. The installation tool  50  includes the cannula  7  discussed earlier and a cap  15  located on the proximal end of cannula  7 . FIG. 7 also shows the installation tool  50  with the suture anchor  100  preparing to enter a pre-drilled hole  10  in a bone  9 . FIG. 8 shows an enlarged view of FIG. 7.  
         [0045]    [0045]FIG. 9 also shows a preferred embodiment of the suture anchor of the present invention prior to insertion. A suture  11  has been threaded through soft tissue  12  and the eyelet  3  in the locking body  75 , which is, in part, covered by anchor collar holder  6 . If the surgeon wishes, the suture  11  may be woven through the soft tissue  12 , thereby allowing for more secure fixation and greater repair strength. The collar  5  is distal to the suture  11  and the eyelet  3 , and proximal to the distal head  2  of the locking body  75 . The anchor collar holder  6  of the installation tool is adjacent to the proximal end of the anchor collar  5 . The suture anchor is positioned to be pushed into pre-drilled hole  10  in bone  9 , to which the soft tissue  12  will be attached. The bone hole  9  is preferably drilled such that the hole reaches through the cortical bone layer to the cancellous bone layer. The hole  9  should be slightly smaller than the width of the distal head  2  of the locking body  75  and the anchor collar  5 . This will allow both the locking body  75  and the anchor collar  5  to gain purchase within the bone hole  10 . Preferably, the suture anchor  100  will ultimately be inserted through bone hole  10  and come to rest in the cancellous bone layer.  
         [0046]    In the embodiment of FIG. 9, there are two lines of suture (both ends of the same strand of suture) that are being passed through the locking body  75 . This provides secure fixation of the soft tissue to the suture anchor. In other embodiments, the number of lines of suture that are passed through the central anchor post may be increased, or decreased, depending upon the particular repair being performed.  
         [0047]    [0047]FIG. 10 shows, in cross-section, a preferred embodiment of the suture anchor of the present invention after being initially inserted into a hole  10  in the bone  9 . The suture threads  11  pass through the locking body  75  and are pulled into the hole  9  in the bone  10 . The distal head  2  of the locking body  75  and the anchor collar  5  are securely positioned within the hole  10  in the bone  9 . As the suture anchor is positioned in the hole  10  in the bone  9 , the soft tissue  12  is pulled to the repair site. The suture  111  may be further pulled through the locking body  75 , thereby drawing the soft tissue  12  even closer to the suture anchor. This allows the surgeon to position and tension the soft tissue  12  appropriately. As the suture threads  11  are pulled, they do not move or “saw” through the soft tissue, thereby lessening the risk that the suture will tear or pull through the soft tissue and result in an ineffective repair.  
         [0048]    [0048]FIG. 11 shows an enlarged view of the proximal end of the installation tool  50 . After insertion of the suture anchor  100  into the pre-drilled bone hole  9 , a portion of the cap  15   a  is removed to reveal push rod  35  Push rod  35  is then pushed by any known means such that the proximal end of the push rod  35  is flush with the proximal end of cannula  7 . By pushing push rod  35 , the locking body  75  is pushed farther into bone  9 . As the anchor collar  5  moves, it engages and locks the suture and locking body  75  into place.  
         [0049]    [0049]FIGS. 12 and 13 show, in cross-section, a preferred embodiment of the suture anchor  100  of the present invention after the locking body  75  has been fully inserted into the hole  10  in the bone  9 . The push rod  35  of the installation tool has pushed the locking body  75  farther into the hole  10  in the bone  9  in the distal direction. The push rod  35  does not push down on the proximal end of the anchor collar  5 , and the anchor collar is not pushed further into the hole  10  in the bone  9 . As a result, the locking body  75  moves distally relative to the anchor collar  5 , thereby expanding the anchor collar  5  to a diameter of θ+δ. The eyelet  3  moves from its location on the proximal side of the anchor collar  5  to a position that is distal to the anchor collar  5 . The suture threads  11  are pulled farther into the hole  10  in the bone  9  and the soft tissue  12  is drawn closer to the bone anchor. The suture threads  11  are now drawn under the anchor collar  5  and are secured by the anchor collar  5 . The suture threads  11  in FIG. 13 may no longer be pulled through the locking body  75 , because they are held tight by the anchor collar  5 . The distal head  2  of the locking body  75  is now securely positioned near the bottom of the hole  10  in the bone  9 .  
         [0050]    In a preferred embodiment, the hole  10  in the bone  9  may be drilled with a tapered drill, so that the distal end of the hole  10  is narrower than its opening. This serves to further prevent the anchor collar  5  from moving distally when the push rod  35  pushes the locking body  75  further into the hole  10 . Additionally, the narrowness of the hole  10  allows the distal head  2  to more securely attach to the bone  9  when the suture anchor  100  is fully installed.  
         [0051]    In yet another preferred embodiment, the anchor collar  5  will deform slightly into an oval shape as the push rod  35  pushes the locking body  75  further into the hole  10  and pulls the suture threads  11  under the anchor collar  5 . As the suture threads  11  travel under the anchor collar  5 , the anchor collar will bow out slightly. This will even more firmily affix the anchor collar within the hole  10  in the bone  9 , ensuring that the suture anchor will not easily pull out of the hole  10 . A preferred pull-out strength for the suture anchor  100 , ranges from approximately 125N to 300N.  
         [0052]    [0052]FIG. 14 shows, in cross-section, a preferred embodiment of the suture anchor  100  of the present invention after the suture anchor has been installed. The installation tool  50  has been removed and the suture threads  11  that have been pulled through the locking body  75  have been cut at the opening of the hole  10 . In a preferred method of insertion, the proximal end of the locking body  75  is positioned below the opening of the hole  10  at the surface of the bone  9  in the cancellous bone layer. This leaves little or no material protruding from the bone  9 , which decreases the risk of foreign material causing irritation or damage within the joint.  
         [0053]    FIGS.  15 - 22  show another embodiment of the suture anchor of the present invention. In this embodiment, the suture anchor  100  includes an anchor collar  5  that has at least one screw thread  80  as a protuberance and likely will have more than one. FIGS.  15 - 17  show the initial configuration of the suture anchor  100 , where the anchor collar  5  is proximal to the locking body. FIGS.  18 - 19  show the final configuration after the locking body  1  has been pushed into bone relative to the anchor collar  5 . FIGS.  20 - 22  also show initial and final configurations of the suture anchor  100  with an installation tool  50 .  
         [0054]    In a preferred procedure for using a suture anchor of the present invention, the surgeon attaches suture thread of his choosing through the soft tissue to be repaired in a manner of his choosing. The suture thread is then drawn through the eyelet in the locking body. The collar is positioned proximal to the eyelet before the suture is drawn through the eyelet. The suture anchor is then inserted partially into the bone through a pre-drilled hole, such that the collar and the locking body are secured within the bone. This may be done by pushing the suture anchor into the pre-drilled hole or screwing the suture anchor into the bone. At this time, the surgeon may tension the suture through the eyelet as he wishes, so that the soft tissue is pulled into approximation with the repair site. When the soft tissue is properly positioned and the suture has been properly tensioned, the surgeon taps the locking body further into the bone. As the locking body moves further into the bone, the collar remains in its initial position, lodged in the bone. Thus, the locking body moves distally with respect to the collar. The eyelet, through which the suture is threaded, moves under and past the collar, thereby drawing the suture under the collar. The collar holds the suture securely, and prevents the soft tissue from pulling away from the repair site. Thus, the suture anchor securely holds the soft tissue in place without requiring the surgeon to knot the suture.  
         [0055]    After the description above of the present invention and certain specific embodiments thereof, it will be readily apparent to those skilled in the art that many variations and modifications may be made to the present invention without departing from the spirit and scope thereof.