Abstract:
The disclosure provides examples of an open architecture anchor for securing soft tissue to bone, for example, to repair a torn rotor cuff. The anchor includes at least one open helical coil defining a polygonal internal volume and at least one rib disposed within the polygonal internal volume and connected to at least two turns of the at least one open helical coil. The at least one rib is sized to engage a driver and a combination of the at least one rib and the polygonal internal volume is sized to provide an anchor drive torque required to drive the anchor into bone.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional application of U.S. patent application Ser. No. 13/838,942, filed Mar. 15, 2013, the disclosure of which is incorporated herein in its entirety. 
     
    
     BACKGROUND 
       [0002]    Arthroscopic surgery is a minimally invasive surgical procedure in which an examination and sometimes treatment of damage of the interior of a joint is performed using an arthroscope, a type of endoscope that is inserted into the joint through a small incision. Arthroscopic procedures, such as repairing a torn rotor cuff, often require soft tissue to be reattached to bone. To achieve this, anchors (sometimes called “suture anchors”) are placed in the bone and sutures attached to the anchor are passed through the tissue to securely retain the tissue in place. 
       SUMMARY 
       [0003]    To reduce the amount of bone stock removed by an anchor and minimize invasiveness, ever smaller open architecture anchors are being used. However, smaller open architecture anchors result in a problematic tradeoff between reduced interior volume of the anchor and weakened drive support structure. In order to maintain structural integrity during screw-in insertion, drive elements must be capable of withstanding the torsion required for insertion of the anchor. Drive ribs are typically provided within an internal volume of an anchor to provide a structural element for a driver to apply torsion during insertion. However, as the size of the anchor is reduced, drive ribs of adequate depth/size to drive an anchor begin to occlude internal suture passages. A need therefore exists for a drive support structure to be capable of withstanding torsional drive forces during anchor insertion and to have a sufficiently small profile to avoid occlusion of internal suture passages. 
         [0004]    The foregoing needs are addressed by an open architecture anchor having a dual drive system using both drive ribs and an internal polygonal (e.g., hexagon, octagon, square, or any other regular or irregular polygon) drive feature. This new dual drive feature allows the anchor to withstand torsional drive forces while including drive ribs of a reduced size. The internal volume of the anchor thereby is maintained such that adequate cross-sectional area is provided for the passage of sutures through the anchor and/or driver. Using a smaller anchor allows for preservation of bone stock and more rapid healing. 
         [0005]    Accordingly, in one aspect, at least one embodiment described herein relates to an anchor for securing soft tissue to bone, for example, to repair a torn rotator cuff. The anchor includes at least one open helical coil defining a polygonal internal volume communicating with a region exterior to the at least one open helical coil through a spacing between turns of the at least one open helical coil, wherein the polygonal internal volume is sized to engage a driver. The anchor also includes at least one rib disposed within the polygonal internal volume and connected to at least two turns of the at least one open helical coil, wherein the at least one rib is sized to engage the driver and a combination of the at least one rib and the polygonal internal volume is sized to provide an anchor drive torque required to drive the anchor into bone. 
         [0006]    Any of the embodiments described herein can include one or more of the following embodiments. In some embodiments the polygonal internal volume further comprises a cross-sectional shape including at least one of a regular polygon; irregular polygon; square, rectangle, triangle, hexagon, and/or octagon. In some embodiments, the at least one rib includes a first rib positioned on a first side of the polygonal internal volume and a second rib positioned on a second side of the polygonal internal volume. In some embodiments, the anchor also includes a suture bridge affixed to and disposed within a distal end of the anchor. In some embodiments, the at least one open helical coil is a dual lead helical coil. 
         [0007]    In another aspect, at least one embodiment described herein provides a tissue repair system. The system includes a driver comprising a handle and a polygonal shaft connected to the handle, at least part of the polygonal shaft having a polygonal-shaped cross-section, the polygonal shaft including a distal end having at least one groove extending toward a proximal end of the polygonal shaft. The system also includes an anchor engageable with a distal end of the driver. The anchor includes at least one open helical coil defining a polygonal internal volume communicating with a region exterior to the at least one open helical coil through a spacing between turns of the at least one open helical coil, wherein the polygonal internal volume is sized to engage the polygonal shaft of the driver. The anchor also includes at least one rib disposed within the polygonal internal volume and connected to at least two turns of the at least one open helical coil, wherein the at least one rib is sized to engage the at least one groove of the driver and a combination of the at least one rib and the polygonal internal volume is sized to provide an anchor drive torque required for the driver to drive the anchor into bone. 
         [0008]    The anchors and systems for tissue repair described herein (hereinafter “technology”) can provide one or more of the following advantages. One advantage of the technology is that a smaller open architecture anchor can be provided by including a polygonal internal volume and reduced profile drive ribs. The combination of the polygonal internal volume and reduced profile drive ribs can advantageously distribute a torsional drive force, thereby maintaining structural integrity during insertion of the anchor into bone despite the reduced size and load capability of the reduced profile drive ribs. The reduced profile drive ribs advantageously allow for smaller open architecture anchors to maintain sufficiently large internal suture passages to pass one or more sutures. The open architecture of the technology advantageously allows for bony ingrowth, thereby reducing patient recovery time. The reduced size of the open architecture advantageously preserves bone stock, thereby preserving bone integrity and reducing patient recovery time. The reduced size of the open architecture also advantageously allows a higher percentage of the diameter of the anchor to be dedicated to thread depth, thereby improving fixation strength of the anchor in the bone. 
         [0009]    Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The foregoing and other objects, features, and advantages will be apparent from the following more particular description of the embodiments as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles, characteristics, and features of the embodiments. In the drawings: 
           [0011]      FIG. 1A  is an end view of a proximal end of an example open architecture anchor in accordance with various embodiments. 
           [0012]      FIG. 1B  is an isometric view of the example open architecture anchor of  FIG. 1  in accordance with various embodiments. 
           [0013]      FIG. 1C  is second isometric view of the example open architecture anchor of  FIG. 1  in accordance with various embodiments. 
           [0014]      FIGS. 2A and 2B  are cross-sectional views of a polygonal internal volume of alternative open architecture anchors in accordance with various embodiments, wherein the ribs have been omitted for clarity. 
           [0015]      FIG. 3A  is an isometric view of an example anchor driver in accordance with various embodiments. 
           [0016]      FIGS. 3B and 3C  are a cross-sectional views of alternative distal ends of the example anchor driver of  FIG. 3A  in accordance with various embodiments. 
           [0017]      FIG. 4  is an isometric view of an example tissue fixation system in accordance with various embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The following description of examples is in no way intended to limit the disclosure, its application, or uses. 
         [0019]      FIGS. 1A -IC show an example of an anchor  100  including at least one (open) helical screw thread  105 . The helical screw thread  105  defines a polygonal internal volume  110  (e.g., hexagonal as shown). The polygonal internal volume  110  communicates with a region exterior to the at least one open helical coil screw  105  through a spacing  115  between turns of the helical screw thread  105 . The polygonal internal volume  110  engages a corresponding polygonal shaft of an anchor driver (e.g., polygonal shaft  301  of anchor driver  300  as shown in  FIGS. 3A-3B ). 
         [0020]    In use, the anchor  100  is located at a distal end of the anchor driver such that the polygonal shaft engages the polygonal internal volume of the anchor  100 . A torsional drive force is then applied to the anchor  100  by the anchor driver to insert the anchor  100  into bone. In various embodiments, the anchor driver can engage the polygonal internal volume  110  along only a portion of the longitudinal length of the anchor (i.e., from proximal end  130   a  to distal end  130   b ). Engagement of substantially the entire length of the polygonal internal volume  110  by the anchor driver, in accordance with various embodiments, can be advantageous because the torsional drive force applied to the anchor  100  during insertion can be distributed throughout the length of the anchor  100 , rather than concentrated on a smaller portion of the anchor  100 . After the anchor  100  is inserted into bone and the patient begins to heal, new bone grows into the internal volume  110  through the spacing  115 . For faster and more complete healing, this “bony ingrowth” is highly desirable. 
         [0021]    In another embodiment, the anchor  100  further includes at least one rib  120  (e.g., two as shown) connected to at least two turns of the helical screw thread  105 . The ribs  120  engage corresponding grooves of an anchor driver (e.g., grooves  305  of anchor driver  300  as shown in  FIGS. 3A-3B ). In use, the anchor  100  is located at a distal end of the anchor driver such that the grooves engage the ribs  120  of the anchor  100 . In various embodiments, a surgeon inserts the anchor  100  into bone using the anchor driver by applying a torsional drive force to the driver, which transmits the torsion to the anchor  100 , thereby screwing the anchor into bone. 
         [0022]    In various embodiments, engagement of the anchor driver with both the polygonal internal volume  110  and the ribs  120  of the anchor  100  advantageously distributes the torsional drive force between the ribs  120  and the polygonal internal volume  110 . Such load distribution, in various embodiments, will allow the anchor  100  to withstand the torsional drive force despite having undersized drive ribs  120 . For example, ribs  120  having a width (w) and/or height (h) too small to independently support the torsional drive force can be used in combination with a polygonal internal volume  110  to establish the necessary structural properties of the anchor  100 . In various embodiments, the anchor driver can engage the polygonal internal volume  110  and/or the ribs  120  along only a portion of the longitudinal length of the anchor (i.e., from proximal end  130   a  to distal end  130   b ). However, engagement of substantially the entire length of the polygonal internal volume  110  and/or the ribs  120  by the anchor driver, in accordance with various embodiments, can be advantageous because the torsional drive force applied to the anchor  100  during insertion can be distributed throughout the length of the anchor  100 , rather than concentrated on a smaller portion of the anchor  100 . This further distribution allows further reduction in width (w) and/or height (h). The reduced width (w) and/or height (h) can, in various embodiments; advantageously prevent occlusion of a cross-sectional area of the polygonal internal volume  110  such that sutures can pass inside the anchor  100  and/or the anchor driver. 
         [0023]    The anchor  100 , in various embodiments, can also include a suture bridge  140  attached to and disposed at least partially within a distal end  130   b  of the anchor  100 . The suture bridge  140  can be located entirely within the distal end  130   b  of the anchor  100  (e.g., as shown in  FIG. 1B ) but can also protrude distally from the distal end  130   b . The suture bridge  140  can, in various embodiments, include a rounded distal-facing region around which one or more sutures can be routed. In such embodiments, a first end of each suture extends proximally through the anchor  100  on a first side of the suture bridge  140   a  and a second end of each suture extends proximally through the anchor  100  on a second side of the suture bridge  140   b . The suture bridge  140  advantageously retains one or more sutures within the anchor  100  while preventing the cutting, pinching, and/or other weakening of the sutures associated with positioning the sutures between the anchor  100  and the bone. 
         [0024]    Some examples of the anchor  100  include two helical screw threads  105  in a “dual lead” thread arrangement. Dual lead means that two “ridges” are wrapped around the anchor  100 . The anchor  100  can be constructed from, for example but not limited to, polymers (e.g., polyetheretherketone), bioabsorbable materials, metals (e.g., surgical steel, titanium), or any other suitable material. 
         [0025]    As shown in  FIGS. 1A, 2A, and 2B , any regular polygonal or irregular polygonal shape can be used for the polygonal internal volume  110 ,  210 ,  260  of the anchor  100 ,  200 ,  250 , respectively, in accordance with various embodiments. Shapes of the polygonal internal volume  110 ,  210 ,  260  can include, for example but are not limited to, a hexagon (e.g., the shape of internal volume  110  as shown in  FIG. 1A ), a rectangle (e.g., the shape of internal volume  210  as shown in  FIG. 2A ), an octagon (e.g., the shape of internal volume  260  as shown in  FIG. 2B ), a triangle, a star-shape, a trapezoid, and/or any other suitable non-circular shape capable of engaging with a driver to receive at least a portion of a transmitted torsional drive force. 
         [0026]      FIGS. 3A-3C  show an anchor driver  300  in accordance with various embodiments. The anchor driver includes a polygonal shaft  301  connected at a proximal end to a handle  303 . The polygonal shaft  301  includes one or more grooves  305  (e.g., two as shown) extending toward a proximal end of the polygonal shaft  301 . The polygonal shaft  301 , in various embodiments, can have a polygonal-shaped cross-section along its entire longitudinal length. In various embodiments, the polygonal shaft  301  can have a polygonal-shaped cross section along only a portion of its longitudinal length and can have at least one different cross-sectional shape (e.g., a different polygon, a circle, an ellipse) along one or more additional portions of its longitudinal length. 
         [0027]    As shown in  FIG. 3B , the one or more grooves  305  can be provided, in various embodiments, as cut-out grooves  305   a  which are open to an interior of the polygonal shaft  301 . As shown in  FIG. 3C , the one or more grooves  305  can be provided, in various embodiments, as channel grooves  305   b . As described above, in various embodiments, the polygonal shaft  301  can be inserted into the polygonal internal volume (e.g.,  110  as described above) of an anchor (e.g.,  100  as described above) to engage the polygonal shaft  301  with the polygonal internal volume and the grooves  305  with the ribs (e.g.,  120  as described above). 
         [0028]    In various embodiments, the handle  303  can be manufactured from a polymer material and via an injection molding process. However, any other suitable material (e.g., metals, composites, wood) and/or process (e.g., extrusion, machining, electro-chemical machining) can be used. The polygonal shaft  301  and/or any surfaces defining a groove  305  thereon can be made from a metal material via an extrusion or drawing process. However, any other suitable material (e.g., plastics, composites) and/or process (e.g., injection molding, casting, machining, electro-chemical machining) can be used. The polygonal shaft  301  can be coupled to the handle  303  via an interference fit. However, any other suitable method of coupling (e.g., screws, adhesives, rivets) can be used. 
         [0029]      FIG. 4  illustrates a tissue fixation system  400  in accordance with various embodiments. The tissue fixation system  400  includes an anchor  410  engaged with a driver  430 . In various embodiments, one or more sutures (not shown) can be installed such that each suture passes around a suture bridge (e.g.,  140  as shown in  FIG. 1 ) and the ends of each suture extend toward a proximal end of the tissue fixation system  400  through the anchor  410 , a grooved polygonal shaft  401  of the anchor driver  430 , and/or a handle  403  of the anchor driver  430 . In various embodiments, a surgeon can apply a torsional drive force to the handle  403 , which transmits the torsional drive force to the grooved polygonal shaft  401  thereby applying the torsional drive force to the anchor  410  to screw the anchor  410  into bone. In various embodiments, the anchor  410  may include, for example but not limited to, any anchor  100 ,  200 ,  250  as described hereinabove with reference to  FIGS. 1A -IC and  FIGS. 2A-2B . In various embodiments, the anchor driver  430 , the handle  403 , and/or the grooved polygonal shaft  401  may include, for example but not limited to, any anchor driver  300 , any polygonal shaft  301 , any grooves  305 ,  305   a ,  305   b , and/or any handle  303  as described hereinabove with reference to  FIGS. 3A-3C . 
         [0030]    As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described examples, but should be defined only in accordance with the following claims appended hereto and their equivalents.