Patent Publication Number: US-11395731-B2

Title: Microanchors for knotless tissue repair

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 15/557,694 filed Sep. 12, 2017, which is a 371 application of International Application No. PCT/US2016/020846, filed Mar. 4, 2016, entitled “MICROANCHORS FOR KNOTLESS TISSUE REPAIR,” which claims priority to and benefit of U.S. Provisional Application No. 62/132,994, filed Mar. 13, 2015, the contents of which are incorporated herein by reference in their entirety for all purposes. 
    
    
     FIELD 
     The present disclosure is generally directed to anchors for approximating a tissue to bone and, more particularly to microanchors for knotless tissue repair. 
     BACKGROUND 
     There is an increasing demand for more types of minimally invasive surgical techniques. Because endoscopic and arthroscopic surgery tends to result in lower morbidity than open surgery, the minimally invasive surgical techniques are very appealing to both patients and physicians. These technologically-advanced procedures include many forms of soft tissue to soft tissue repairs and soft tissue to bone repair. Examples of these procedures in orthopedic surgery include rotator cuff repair, labral repair, biceps tenodesis, and anterior cruciate ligament reconstruction. Other examples in other surgical subspecialties include, but are not limited to, hernia repair, hysterectomies, and laparoscopic gastric bypass. 
     Many of the above mentioned tissue repair procedures involve approximating the tissue to a bone by deploying an anchor into the bone, and tying the tissue to the anchor with a suture. In a number of suture anchors, the suture is passed through an eyelet located on the proximal end of the anchor and passed through the tissue. (See, for example, U.S. Patent Publication No. 2002/0052629 and U.S. Pat. No. 5,370,662, where a suture is passed through an eyelet located on the proximal end of the anchor.) In order to use these suture anchors, however, the diameter of the hole drilled into the bone is generally in excess of 2.5 mm due to the need to manage four or more suture limbs, the anchor body, and the eyelet structure. While this may be acceptable in certain procedures, there are a number of procedures that would benefit from a smaller bone hole. For example, the procedure for reattaching the labrum to the acetabular rim in a hip repair would benefit by use of a smaller bone hole. It is therefore desirable to reduce the diameter of both the anchoring structure and the bone hole. Reducing the size of the bone hole and the anchor tends to make the tissue repair less traumatic and leads to a shorter patient recovery time. 
     SUMMARY OF THE DISCLOSURE 
     Described herein is a knotless anchor for securing a tissue to a bone in a human or animal including a rigid anchor body and a suture secured thereto. As described further herein, the parallel direction or orientation of a suture tunnel reduces the number of suture limbs required to fixate a tissue to bone. The reduction in the number of suture limbs arises because the suture itself forms the eyelet, eliminating the need of a separate laterally-disposed eyelet structure. It is estimated that the effective diameter is reduced by an amount equal to at least the cross sectional area of one suture plus the cross sectional area of the eyelet mechanism. Additionally, the bone fixation features compress the suture between the bone wall and an exterior surface of the rigid anchor body when the anchor body is deployed in a bone hole. Embodiments described herein bind the suture and prevent tissue pull out. Advantageously, the anchor operates without the need to tie a knot, without adding blocking protrusions or obstacles along the suture, and without use of multiple actuatable/moving internal components for clamping the suture. 
     In embodiments, the suture and the rigid anchor body are securely connected by bonding, heat staking, ultrasonic welding or staking, ultrasonic molding, or injection molding. 
     In embodiments, the fixed limb portion of the suture includes a suture tunnel. The suture tunnel commences at a suture entry port and terminates at a suture exit port. 
     In embodiments, the rigid anchor body comprises at least one bone locking feature such as but not limited to an exterior barb, ridge, thread, or rib. 
     In embodiments, the suture is locked by compressing the suture between an exterior surface of the anchor body and the interior surface of the bone hole. 
     In embodiments, an anchor assembly comprises an anchor as described above and a snare extending through the suture eyelet. The snare is configured to draw the free end of the suture through the eyelet. The anchor assembly may also include an inserter tube for supporting and manipulating the anchor into the bone hole. 
     In embodiments, the anchor assembly may also include an advancer (or die) tube abutting the proximal end of the anchor body and for holding the anchor body in the bone hole as the inserter tube is retracted. 
     In embodiments, a method of anchoring a tissue to a bone of a human or an animal without tying a knot comprises passing a free suture limb through the tissue. The fixed suture limb is secured to a rigid anchor body. The free suture limb is drawn through a suture tunnel formed in the fixed suture limb thereby defining a closable suture loop around the tissue. The tissue is approximated towards the anchor body by closing the suture loop. The anchor body is inserted into a bone hole whereby the suture is compressed between an internal wall of the bone hole and an exterior feature of the anchor body thereby locking the suture and affixing the tissue to the bone. 
     In embodiments, the method further comprises providing the fixed suture limb on an exterior of the anchor body. 
     In embodiments, a multi-row tissue fixation method for anchoring a tissue to a bone without tying a knot comprises providing a first and a second rigid anchor body. A fixed suture limb is joined to each of the rigid anchor bodies. A free suture limb extends from each of the anchor bodies. The method further comprises deploying the first and second anchor bodies in first and second bone holes respectively. The free suture limbs are passed through the tissue. The tissue is approximated to the bone by applying tension to the free suture limbs of the first and second sutures until the tissue is positioned as desired. 
     In embodiments, the multi-row tissue fixation method further comprises threading the first and second free suture limbs through at least a third anchor body. 
     In embodiments, the multi-row tissue fixation method further comprises threading the first and second free suture limbs through third and fourth anchor bodies respectively. 
     In embodiments, the multi-row tissue fixation method further comprises deploying the third and fourth anchor bodies in third and fourth bone holes respectively. 
     In embodiments, the multi-row tissue fixation method further comprises creating the third and fourth bone holes in lateral locations relative to the first and second bone holes, the first and second bone holes being medially disposed. 
     In embodiments, a multi-row tissue fixation method further comprises a first suture having a non-hollow or tape-like shape. 
     Aspects of the present disclosure advantageously improve upon some of the previous anchor designs by, amongst other things, reducing the footprint of the bone hole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features will be apparent from the following description of particular embodiments disclosed herein, as illustrated in the accompanying drawings. 
         FIG. 1 a    is a perspective view of an anchor comprising a soft suture tunnel secured to an exterior surface of the anchor body; 
         FIGS. 1 b - c    are details of the interface between the soft suture tunnel and the anchor body of  FIG. 1   a;    
         FIG. 2  is a perspective view of another anchor comprising a soft suture tunnel partially incorporated into the anchor body; 
         FIG. 3  is a cross sectional view of the anchor shown in  FIG. 2 , taken along line  3 - 3 ; 
         FIG. 4  is a perspective view of another anchor including a hard suture tunnel extending through the anchor body; 
         FIG. 5 a    is a perspective view of another anchor including a suture tunnel extending through the anchor body; 
         FIG. 5 b    is a cross sectional view of the anchor shown in  FIG. 5 a   , taken along line  5   b - 5   b;    
         FIGS. 6-10  are illustrations of a method for approximating a tissue to bone; 
         FIG. 11  is a perspective view of another anchor for approximating a tissue to bone; and 
         FIGS. 12-13  are illustrations of multi-row tissue fixation methods for approximating tissue to a bone. 
     
    
    
     DETAILED DESCRIPTION 
     Before the present disclosure is described in detail, it is to be understood that this disclosure is not limited to particular variations set forth herein as various changes or modifications may be made to the disclosure described and equivalents may be substituted without departing from the spirit and scope of the disclosure. As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present disclosure. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process act(s) or step(s) to the objective(s), spirit or scope of the present disclosure. All such modifications are intended to be within the scope of the claims made herein. 
     Methods recited herein may be carried out in any order of the recited events which is logically possible, as well as the recited order of events. Furthermore, where a range of values is provided, it is understood that every intervening value, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the disclosure. Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. 
     All existing subject matter mentioned herein (e.g., publications, patents, patent applications and hardware) is incorporated by reference herein in its entirety except insofar as the subject matter may conflict with that of the present disclosure (in which case what is present herein shall prevail). The referenced items are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present disclosure is not entitled to antedate such material by virtue of prior disclosure. 
     Reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “an,” “said” and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. Last, it is to be appreciated that unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. 
     With reference to  FIG. 1 a   , for example, a knotless anchor  10  for securing soft tissue to bone is shown. In embodiments, the anchor  10  comprises a rigid anchor body  12 , and a length of suture  14  secured to an external surface of the anchor body  12 . The anchor body  12  may comprise a single or unitary rigid body. A fixed end  16  of the suture  14  is secured along the exterior of the anchor body  12 . The fixed end  16  is shown affixed between the proximal and distal end of the anchor body  12 . As described further herein, the other end of the suture  14  is a free end  30  and is threaded through the tissue to be approximated to the bone. Exemplary materials for the suture  14  are PGA, PGLA, or Ultra-high-molecular-weight polyethylene (namely, UHMWPE). The suture  14  is preferably hollow and braided. The suture  14  may have a variable pitch of the yarn. In embodiments, the suture  14  has a low pitch, permitting the hollow braid to more easily expand over the anchor body  12  than a high pitch braid. In embodiments, a section of flat tape (not shown) is incorporated into the suture  14  in order to spread tension load where the tape/suture is to contact the tissue. 
     In the embodiment shown in  FIG. 1 a   , the suture  14  is a soft hollow member (e.g., a hollow braid). It is secured in a predominantly parallel orientation to the longitudinal axis of the anchor body  12 . The fixed end  16  of the suture  14  operates as an eyelet for passage of the free end  30 . A first port  22  and a second port  24  are shown in the hollow braided suture  14 . The first port  22  and the second port  24  can be used be as a suture entry port and suture exit port respectively. Alternatively, the first port  22  could be used as an exit port and the second port  24  could be used as an entry port. A suture lumen or tunnel  32  extends parallel to the axis of the anchor body  12  and connects the first port  22  to the second port  24 . The free end  30  of the suture  14  is passed through tissue, then through tunnel  32 , resulting in only three limbs extending from the bone hole (rather than four limbs), advantageously providing a reduced diameter when compared to other anchor designs. 
     With reference again to  FIG. 1 a   , the length of the tunnel  32  may range from about 1 mm to about 12 mm. The diameter of the tunnel  32  may range from about 0.2 mm to about 2 mm. The tunnel  32  and suture  14  are preferably unitary continuous components of the knotless anchor  10 , and not separate members or assemblies which can undesirably make the anchor footprint larger and more complex. The cross section of the knotless anchor  10  (i.e., suture  14  plus anchor body  12 ) is about the same diameter as the suture  14  itself, or maybe slightly larger (e.g., 10-15%, or up to 25% larger) to accommodate the diameter of the anchor body  12 . Bone fixation features, such as ridges  28 , are shown on the anchor body  12 . However, the bone fixation features may vary widely. Screw threads, barbs, ribs, protrusions, or a smooth shell can be utilized to secure the anchor body  12  in bone. The bone fixation features serve to grip internal walls of the bone hole when the anchor body  12  is installed. 
     As detailed in  FIG. 1 b   , the suture  14  and the anchor body  12  may be connected in various ways. For example, the suture  14  can be connected to the anchor body  12  via bonding, ultrasonic welding or staking, or heat staking. Mechanical interlocking features  13  incorporated into the anchor body  12  that pierce or engage the suture  14  may aid the assembly process. The materials and size of the anchor body  12  and suture  14  may be selected such that the melt temperature of the anchor body  12  is lower or equal to the melt temperature of the suture  14  for ease of assembly. Alternatively, if the melt temperature of the anchor body  12  is higher than the melt temperature of the suture  14 , the attachment can still be formed because the actual polymer melt profile can be a lower temperature at the suture interface and managed to limit damage to the suture  14 . As shown in  FIG. 1 c   , displacement and or deformation  17  of mechanical interlocking features  13  ( FIG. 1 b   ) on the anchor body  12  that engage the suture  14  via ultrasonic welding or staking, or heat staking is a suitable assembly process to limit damage to the suture  14 . Suitable materials for the anchor body  12  include without limitation PEEK, PLLA, REGENESORB™ (manufactured by Smith &amp; Nephew plc, London England), and other biocompatible or bioabsorbable materials. Insert molding the anchor body  12  to the suture  14  via ultrasonic molding or injection molding are also viable assembly methods. In embodiments, the suture  14  is connected to the anchor body  12  without a knot. 
       FIG. 2  illustrates an alternative embodiment of a knotless anchor  40  for attaching tissue to bone. Anchor  40  is similar to the anchor  10  shown in  FIG. 1 a    except that the suture  44  is partially integrated into (insert molded, bonded, or staked to) the anchor body  42 . The fixed end  46  of the suture  44  can be joined to the anchor body  42  via heat staking or molding. A suture tunnel  56  extends from the first port  52  to the second port  54 . The suture tunnel  56  acts as an eyelet running parallel to the longitudinal axis of the anchor body  42 . As described herein, incorporating the suture tunnel  56  along the longitudinal axis of the anchor body  42  reduces the diameter of the anchor  40  compared to anchors having a tunnel (or eyelet) perpendicular to the anchor body.  FIG. 3  shows a cross-sectional view of the anchor  40  shown in  FIG. 2 , taken along line  3 - 3   
       FIG. 4  shows another knotless anchor  60  for attaching tissue to bone. The anchor  60  shown in  FIG. 4  is similar to the anchor  10  shown in  FIG. 1 a    except that both the anchor body  62  and the suture  64  have a suture tunnel  68  extending in the longitudinal direction. The fixed end  66  circumferentially or radially surrounds the hard anchor body  62 . The anchor  60  shown in  FIG. 4  thus comprises a hard tunnel coaxially arranged within a soft tunnel. 
       FIG. 5 a    shows another knotless anchor  80  for attaching tissue to bone. The anchor  80  shown in  FIG. 5 a    is similar to that shown in  FIG. 4  except the fixed end  84  is secure internally to the anchor body  88 . More specifically, the fixed end  84  is secure within hard lumen  86  of the anchor body  88 . The fixed end  84  includes a first port  94  and a second port  96 . Therefore, in anchor  80 , the axially or longitudinally disposed soft tunnel is coaxially arranged within the hard tunnel. 
     With reference to  FIG. 5 b   , a cross-sectional view of the anchor  80  is shown, taken along line  5   b - 5   b . A preferred range for the internal diameter D 1  of the lumen  86  is about 0.5 mm to about 8 mm. A preferred range for the outer diameter D 2  of anchor body  88  is about 1.2 mm to about 2.5 mm. However, it is to be understood that the anchor  80  may have other dimensions. 
       FIGS. 6-10  illustrate a method of deploying an anchor  116  and approximating tissue  104  to bone  110 . Although the anchor  116  shown in  FIGS. 6-10  is similar to anchors described above in connection with  FIGS. 5 a -5 b   , other anchor configurations may be utilized in accordance with methods described herein. 
       FIG. 6  shows an anchor  116  comprising a fixed suture end  101  secured to the anchor  116  and a free suture end  102  which has been passed through tissue  104 . A non-limiting example of a suture passer to deliver the suture free end through the tissue is the ACCU-PASS device manufactured by Smith &amp; Nephew Corporation, Austin Tex., U.S.A.  FIG. 6  also shows the free suture end  102  fed into a snare loop  106  having snare handle  108 . 
     Next, and with reference to  FIG. 7 , snare handle  108  ( FIG. 6 ) is pulled, drawing the free suture end  102  through the anchor  116 . Free suture end  102  is drawn through the longitudinally disposed soft eyelet  112  formed by the suture  120 . Stated alternatively, the suture  120  is drawn through (or fed into) itself. As free suture end  102  is further pulled, a closable loop  119  is formed and drawn over a portion of the tissue  104 . Thus, a suture path commences at the fixed suture end  101  on the anchor  116 , extends through the tissue  104 , and returns to the anchor  116 , continues through the soft eyelet  112  of the suture  120 , and terminates at the free suture end  102 . Free suture end  102  may be pulled by the physician to the desired tensional force. With reference to  FIG. 8 , tension (T) is applied to the free suture end  102  until a desired level of force or resistance is achieved. Tissue  104  is now shown in close proximity or adjacent anchor body  116 . 
     With reference to  FIG. 9 , an inserter  114  is shown mating with a proximal surface of the anchor body  116 . The inserter  114 , as described herein, assists with positioning the anchor  116  in the bone hole  118 . Additionally, in embodiments, the inserter  114  may comprise an internal, axially slidable die member  115  to cooperate with an internal key hole (not shown) of the anchor  116 . The inserter  114  holds the anchor  116  in place as the internal die member  115  is retracted. The components of the inserter  114  cooperate together to place, hold, and deploy the anchor  116  in the bone hole. Non-limiting examples of inserter members, dies, and handles are described in, for example, U.S. Pat. No. 6,780,198 to Gregoire et al. 
       FIG. 9  also illustrates the anchor  116  being inserted into a pre-drilled bone hole  118 . However, in embodiments, the anchor  116  may be pounded directly into a bone, creating the bone hole  118  as it is pounded into the bone. In embodiments, the distal end of the anchor  116  includes a hard, pointed edge to facilitate cutting through the bone. The anchor  116  may also include self-tapping threads to dig and grip the bone. In the assembly shown in  FIG. 9 , the suture  120  is compressed between the interior wall of the bone hole  118  and the rigid exterior surface of the anchor  116 . Ridges on the surface of the anchor ( FIG. 1 ) make contact with the suture  120  and securely hold the suture  120  in place. The suture  120  is compressed and locked. The anchor  116  may be adjusted to a depth, as shown, safely below the relatively hard cortical bone layer indicated by reference numeral  122 . 
       FIG. 10  shows the tissue  104  secured to the bone. The inserter  114  removed, and the free suture end  102  trimmed. Notably, the embodiment shown in  FIG. 10  includes only three suture limbs  102 ,  134 ,  136  extending from the anchor  116 . This reduction in the number of suture limbs arises from the soft eyelet  112  present along the longitudinal axis. Consequently, a larger laterally-disposed eyelet (or other type of suture loop/connector) is not necessary for tissue fixation. 
       FIG. 11  shows another anchor  202  including a rigid anchor body  204  and a suture  206  secure thereto. The embodiment shown in  FIG. 11 , however, differs from the previous described embodiments in that the anchor  202  does not feature a suture tunnel or eyelet. The fixed suture end  210  is preferably a suture tape or non-hollow suture. The free suture end  208  is directly affixed to a lateral aspect of the rigid anchor body  204 . Alternatively, the free suture end  208  may be bonded, staked, or joined internally to anchor body  204 . The tape or non-hollow suture is preferred in this embodiment so as to reduce the diameter or footprint of the bone hole. As described herein, anchor  202  can be useful in double or multi-row tissue fixation procedures. In another embodiment, the rigid anchor body  204  may include a hole (not shown) traversing the longitudinal axis to serve as an eyelet or insertion aid. 
       FIG. 12  is an illustration of a multi-row tissue fixation technique comprising a first set of anchors  210   a ,  210   b  and a second set of anchors  212   a ,  212   b . The second or additional set  212   a ,  212   b  are intended to provide better purchase on the tissue  214 . In a double row procedure, medial anchors  210   a ,  212   a  (an example of which is shown in  FIG. 11 ) may be pounded or installed into the medial bone holes. Free suture ends  216   a ,  216   b  are passed through the tissue  214  (e.g., a labrum or tendon). Free suture ends  216   a ,  216   b  are snared or otherwise threaded through suture eyelets of the lateral anchors  210   b ,  212   b . Lateral anchors  210   b ,  212   b  may include the self-contained suture tunnels as described above. Tension is applied to free suture ends  216   a ,  216   b  until a desired force across the tissue  214  is achieved. The lateral anchors  210   b ,  212   b  are then deployed in the bone holes  218 ,  220 , thereby locking the suture and anchors in the bone holes. The free suture ends  216   a ,  216   b  are trimmed. 
     The above-described double row technique utilizes smaller-diameter implants, and consequently reduces the size of the bone hole. In particular, in embodiments, less than four suture limbs (or in some embodiments less than three suture limbs) are necessary to carry out the tissue fixation procedure. The medial anchors  210   a ,  212   a , for example, have only one suture limb extending therefrom, the suture being non-hollow or flat. Additionally, the lateral anchors  210   b ,  212   b  show only two suture limbs extending from the proximal end of the anchor. Smaller diameter bone holes and hardware are therefore enabled by the anchors and procedure described in connection with  FIGS. 11-12 . 
       FIG. 13  is an illustration of another multi-row tissue fixation technique comprising a first set of medial anchors  230   a ,  230   b  and a second anchor  232 . The technique shown in  FIG. 13  is similar to that shown in  FIG. 12  except that the two suture free ends  240 ,  242  are shown threaded through sole lateral anchor  232 . Lateral anchor  232  has an internal lumen to accommodate both suture free ends  240 ,  242 , and features a suture lock wholly independent of the bone lock mechanisms. For example, the anchor may be deployed in the bone hole, and after the anchor is properly seated in the bone hole, the suture may be tensioned and then locked within the anchor. A non-limiting example of an anchor similar to the anchor  232  shown in  FIG. 13  is the SpeedScrew Knotless Fixation Device (Manufactured by Arthrocare Corporation, Austin, Tex.). The sutures are then trimmed. 
     Although  FIGS. 11-13  illustrate double row configurations, the disclosure is not so limited. In embodiments, at least three rows of anchors may be deployed to achieve better tissue purchase and stability. Additionally, a number of non-limiting examples of multi- or double row techniques may be combined with aspects described herein including, without limitation, the multi-row fixation techniques described in connection with the Speedscrew™, Labralock™, and Speedlock™-brand knotless implants manufactured by ArthroCare Corporation, Austin Tex., U.S.A., and the suture described in U.S. Pat. No. 8,818,326 to Gagliano. 
     Although the present disclosure is suitable for attaching the labrum to the acetabular rim in a hip surgery, it is also applicable to other tissue fixation procedures including attachment of the rotator cuff tendon to the humeral head, or other tissue to bone and tissue to tissue procedures. Indeed, the present disclosure is suitable for hip, shoulder, and small joint repair. It is particularly desirable for repairs requiring a relatively small footprint. 
     While preferred embodiments of this disclosure have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teaching herein. The embodiments described herein are exemplary only and are not intended to be limiting. Because many varying and different embodiments may be made within the scope of the present inventive concept, including equivalent structures, materials, or methods hereafter thought of, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirements of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.