Abstract:
A multi-suture knotless anchor and related method for securing soft tissue, such as tendons, to bone are described. The suture anchor includes a body, a sleeve, and an outer deformable bone locking structure. The bone locking structure has a first low profile configuration for insertion into the bone, and a second larger profile configuration for engaging the bone when actuated. The bone anchor and methods permit a suture attachment that lies beneath the cortical bone surface and does not require tying of knots in the suture.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to methods and apparatus for attaching soft tissue to bone, and more particularly to anchors and methods for securing connective tissue, such as ligaments or tendons, to bone. The invention has particular application to arthroscopic surgical techniques for reattaching soft tissue in a minimally invasive procedure. 
         [0002]    Less invasive arthroscopic techniques are continuing to be developed in an effort to address the shortcomings of open surgical repair. Working through small trocar portals allow surgeons to cause less trauma than an open procedure. However, less invasive techniques present unique challenges as the surgeon has less space to manipulate tools and implants. 
         [0003]    Unfortunately, the skill level required to facilitate entirely arthroscopic repair tissue is inordinately high. Intracorporeal suturing is clumsy and time consuming, and only the simplest stitch patterns can be utilized. Extracorporeal knot tying is somewhat less difficult, but the tightness of the knots is difficult to judge, and the tension cannot later be adjusted. Also, because of the use of bone anchors to provide a suture fixation point in the bone, the knots that secure the soft tissues to the anchor by necessity leave the knot bundle on top of the soft tissues. In the case of certain procedures the knot bundle left in the tissue can be felt by the patient postoperatively when the patient exercises the joint. Often the knots tied arthroscopically are difficult to achieve, impossible to adjust, and are located in less than optimal areas of the shoulder. Suture tension is also impossible to measure and adjust once the knot has been fixed. 
         [0004]    Another significant difficulty with current arthroscopic repair techniques is shortcomings related to currently available suture anchors. Suture eyelets in bone anchors available today, which like the eye of a needle are threaded with the thread or suture, are small in radius, and can cause the suture to fail at the eyelet when the anchor is placed under high tensile loads. 
         [0005]    There are various bone anchor designs available for use by an orthopedic surgeon for attachment of soft tissues to bone. The basic commonality between the designs is that they create an attachment point in the bone for a suture that may then be passed through the soft tissues and tied, thereby immobilizing the soft tissue. This attachment point may be accomplished by different means. Screws are known for creating such attachments, but suffer from a number of disadvantages, including their tendency to loosen over time, requiring a second procedure to later remove them, and their requirement for a relatively flat attachment geometry. 
         [0006]    Another approach is to utilize the difference in density in the cortical bone (the tough, dense outer layer of bone) and the cancellous bone (the less dense, and somewhat vascular interior of the bone). The cortical bone presents a kind of hard shell over the less dense cancellous bone. The aspect ratio of the anchor is such that it typically has a longer axis and a shorter axis and usually is pre-threaded with a suture. These designs use a hole in the cortical bone through which an anchor is inserted. The hole is drilled such that the shorter axis of the anchor will fit through the diameter of the hole, with the longer axis of the anchor being parallel to the axis of the drilled hole. After deployment in to the cancellous bone, the anchor is rotated 90 degrees so that the long axis is aligned perpendicularly to the axis of the hole. The suture is pulled, and the anchor is seated up against the inside surface of the cortical layer of bone. Due to the mismatch in the dimensions of the long axis of the anchor and the hole diameter, the anchor cannot be retracted proximally from the hole, thus providing resistance to pull-out. These anchors still suffer from the aforementioned problem of eyelet design that stresses the sutures. 
         [0007]    Still other prior art approaches have attempted to use a “pop rivet” approach. This type of design requires a hole in the cortical bone into which a split shaft is inserted. The split shaft is hollow, and has a tapered plug leading into its inner lumen. The tapered plug is extended out through the top of the shaft, and when the plug is retracted into the inner lumen, the tapered portion causes the split shaft to be flared outwardly, locking the device into the bone. 
         [0008]    Other methods of securing soft tissue to bone are known in the prior art, but are not presently considered to be feasible for shoulder repair procedures, because of physicians&#39; reluctance to leave anything but a suture in the capsule area of the shoulder. The reason for this is that staples, tacks, and the like could possibly fall out and cause injury during movement. As a result of this constraint, the attachment point often must be located at a less than ideal position. Also, the tacks or staples require a substantial hole in the soft tissue, and make it difficult for the surgeon to precisely locate the soft tissue relative to the bone. 
         [0009]    As previously discussed, any of the anchor points for sutures mentioned above require that a length of suture be passed through an eyelet fashioned in the anchor and then looped through the soft tissues and tied down to complete the securement. Much skill is required, however, to both place the sutures in the soft tissues, and to tie knots while working through a trocar under endoscopic visualization. 
         [0010]    There have been attempts to solve some of the problems that exist in current anchor designs. One such approach is disclosed in U.S. Pat. No. 5,324,308 issued to Pierce. In this patent, there is disclosed a suture anchor that incorporates a proximal and distal wedge component having inclined mating faces. The distal wedge component has two suture thread holes at its base through which a length of suture may be threaded. The assembly may be placed in a drilled hole in the bone, and when tension is placed on the suture, the distal wedge block is caused to ride up against the proximal wedge block, expanding the projected area within the drilled hole, and locking the anchor into the bone. This approach is a useful method for creating an anchor point for the suture, but does not in any way address the problem of tying knots in the suture to fix the soft tissue to the bone. 
         [0011]    The problem of placing sutures in soft tissues and tying knots in an endoscopic environment is well known, and there have been attempts to address the problem and to simplify the process of suture fixation. One such approach is disclosed in U.S. Pat. No. 5,383,905 issued to Golds et al. The patent describes a device for securing a suture loop about bodily tissue that includes a bead member having a longitudinal bore and an anchor member adapted to be slidably inserted within the bore of the bead member. The anchor member includes at least two axial compressible sections which define a passageway to receive two end portions of a suture loop. The axial sections collapse radially inwardly upon insertion of the anchor member within the bore of the bead member to securely wedge the suture end portions received within the passageway. 
         [0012]    Although the Golds et al. patent approach utilizes a wedge-shaped member to lock the sutures in place, the suture legs are passing through the bore of the bead only one time, in a proximal to distal direction, and are locked by the collapsing of the wedge, which creates an interference on the longitudinal bore of the anchor member. Also, no provision is made in this design for attachment of sutures to bone. The design is primarily suited for locking a suture loop, such as is used for ligation or approximation of soft tissues. 
         [0013]    An approach that includes bone attachment is described in U.S. Pat. No. 5,584,835 issued to Greenfield. In this patent, a two part device for attaching soft tissue to bone is shown. A bone anchor portion is screwed into a hole in the bone, and is disposed to accept a plug that has been adapted to receive sutures. In one embodiment, the suture plug is configured so that when it is forced into its receptacle in the bone anchor portion, sutures that have been passed through an eyelet in the plug are trapped by friction between the wall of the anchor portion and the body of the plug portion. 
         [0014]    Although there is some merit to this approach for eliminating the need for knots in the attachment of sutures to bone, a problem with being able to properly set the tension in the sutures exists. The user is required to pull on the sutures until appropriate tension is achieved, and then to set the plug portion into the bone anchor portion. This action increases the tension in the sutures, and may garrote the soft tissues or increase the tension in the sutures beyond the tensile strength of the material, breaking the sutures. In addition, the minimal surface area provided by this anchor design for pinching or locking the sutures in place will abrade or damage the suture such that the suture&#39;s ability to resist load will be compromised. 
         [0015]    A disclosure that incorporates bone attachment and eliminates knot tying is set forth in U.S. Pat. No. 5,702,397 issued to Goble et al. One embodiment, in particular, is shown in FIG. 23 of that patent and includes a bone anchor that has a threaded body with an inner cavity. The cavity is open to one end of the threaded body, and joins two lumens that run out to the other end of the threaded body. Within the cavity is disposed a gear, journaled on an axle. A length of suture is threaded through one lumen, around the gear, and out through the other lumen. A ball is disposed within the cavity to ride against a tapered race and lock the suture in place. What is not clear from the patent disclosure is how the force D shown as the tension in the suture would lock the ball into the race. Although this embodiment purports to be a self-locking anchor adapted for use in blind holes for fixing sutures into bone, the construct shown is complicated, and does not appear to be adequate to reliably fixate the suture. 
         [0016]    PCT Publication WO 01/10312 by McDevitt et al. also describes a self-locking suture anchor for attaching soft tissue to bone. In this device a tissue anchor holds a filament within the anchor so that an applied force greater than a threshold force causes the filament to move longitudinally, while an applied force that is less than the threshold force does not move the filament. 
         [0017]    U.S. Patent Publication No. 2008/0051836 by Foerster et al. describes knotless bone anchor body having an outer rigid anchoring structure and an interior lumen. The lumen is sized to receive a locking plug and to compress and lock a suture situated therein. 
         [0018]    A number of the suture anchors described above have static or fixed barbed anchor designs. Namely, the outer diameter of the anchoring structure is fixed (or constant) irrespective of the bone quality. This is a disadvantage when the bone is relatively soft. The anchor may have a tendency to pull out. 
         [0019]    Despite the above, a new approach is desired for repairing or fixing soft tissues to bone. In particular a new approach is desired that embeds a suture anchor below the cortical bone surface, utilizes multiple sutures, and is knotless. 
       SUMMARY OF THE INVENTION 
       [0020]    A suture anchor for securing a soft tissue to a bone with at least one suture comprises a first undeployed configuration in which tissue may be drawn towards the suture anchor by applying tension to a free limb of the suture, and a second deployed configuration in which the suture anchor is fixed in the bone and the suture is locked in the suture anchor thereby securing the tissue to the bone. The suture anchor includes: an anchor body having a proximal section, an elongate intermediate section, and a distal section; a bone locking member at least partially disposed about the elongate intermediate section and forming a cavity between an inner surface of the bone locking member and an outer surface of the elongate intermediate section. The suture anchor also includes a sleeve member which moveably cooperates with the anchor body and the bone locking member to slide into the cavity along the elongate intermediate section thereby expanding the bone locking member and compressing the at least one suture between the outer surface of the elongate intermediate section and an inner surface of the sleeve member. The shape of the cavity may vary. In one embodiment the cavity has an annular shape. 
         [0021]    In another embodiment, the bone locking member comprises a plurality of deflecting sections which deflect outwardly from the anchor body when the sleeve member is urged into the cavity. The plurality of deflecting sections may comprise wings. In one embodiment, the plurality of wings comprise at least three discrete wings. 
         [0022]    In another embodiment, the suture anchor comprises a bone piercing tip. The bone piercing tip may taper from a proximal base to a distal end. The base may have an outer diameter of at least 4 mm. 
         [0023]    In another embodiment the suture anchor body comprises a suture guide which guides the suture from one side of the anchor body to the other side of the anchor body. The suture guide may be an aperture extending through the distal section of the anchor body. 
         [0024]    In another embodiment, the suture anchor comprises ridges which engage the bone to hold the anchor in the bone. The ridges may be situated on the bone locking member and/or the sleeve. Additionally, the distal section of the anchor body may comprise ridges. 
         [0025]    The suture anchor may be formed of various materials. In one embodiment, the suture anchor is formed of a biocompatible polymer. 
         [0026]    In another embodiment a knotless suture anchoring system for anchoring a length of suture with respect to a bone comprises: an anchor insertion instrument comprising a handle, and an elongate rigid shaft extending distally from the handle; an anchor body detachably connected to the instrument elongate rigid shaft. The anchor body comprising a suture carrying portion allowing the suture to pass from a first side of the anchor body to an opposite side of the anchor body. The anchoring system further comprising a bone locking member disposed on the anchor body. In embodiments, the bone locking member comprises a bone anchoring structure extending from a base and radially spaced from the intermediate section of the anchor body such that a cavity is defined between an outer surface of the anchor body and the inner surface of the bone anchoring structure. The cavity is sufficient in size to allow the length of suture to be drawn through the cavity and to the suture carrying portion. The anchoring system also includes a sleeve member slidably disposed on the shaft distal end section of the instrument and proximal to the anchor body. The sleeve member has an outer diameter sufficient in size and shape to radially expand the anchoring structure when pushed along the shaft distal end section and into the cavity, and the sleeve member having an inner diameter sufficient in size and shape to compress a length of suture between the anchor body and an inner surface of the sleeve. 
         [0027]    In another embodiment the system comprises a snare extending through at least a portion of the insertion instrument and the suture carrying portion of the anchor bone such that when a distal portion of the snare is affixed to the suture, withdrawal of the snare pulls the suture through the suture carrying portion of the anchor body and the distal portion of the insertion instrument. 
         [0028]    In another embodiment, the distal end section of the anchor comprises a pointed tip. 
         [0029]    In another embodiment, the system includes a section of tensile weakness or engineered notch along the instrument shaft permitting the shaft to be detached from the anchor body proximal end upon application of a predetermined tensile force on the shaft in the proximal direction. 
         [0030]    In another embodiment a method for knotless securing of soft tissue to bone comprises stitching tissue with at least one suture; loading an anchor assembly with the at least one suture, the anchor assembly being detachably connected to the end of an insertion instrument; manipulating the anchor assembly into the bone; tensioning a free end of the suture to approximate the tissue to the anchor assembly; moving a sleeve member into the anchor assembly to deploy a bone locking structure of the anchor assembly and to compress the suture; and retracting the insertion instrument leaving the anchor assembly embedded in the bone, and the tissue secured to the bone. 
         [0031]    In another embodiment loading the anchor assembly with the at least one suture comprises loading the anchor assembly with a plurality of sutures. 
         [0032]    In another embodiment loading the anchor assembly is performed by snaring the sutures. Snaring may be performed by inserting the lengths of the sutures in a wire loop of a snare device detachably affixed to the distal section of the shaft, and pulling on a snare grip to draw the sutures through the anchor assembly and the instrument. 
         [0033]    In another embodiment manipulating the anchor and suture into a bone comprises hammering the proximal end of the insertion instrument. Also, in embodiments, the tensioning is performed prior to the manipulating step. The tensioning may be performed semi-automatically 
         [0034]    In another embodiment the tissue is a rotator cuff tendon and the bone is the humeral head. 
         [0035]    In another embodiment the moving step includes compressing a first section of suture between the anchor body and the sleeve member and a second section of the suture between a bone surface and an exterior of the bone locking structure. The moving step may include pushing the sleeve into the cavity until a stop on the anchor body prevents further movement. 
         [0036]    In another embodiment, the method comprises toggling the anchor assembly to a tilt angle. The toggling may be performed by applying tension on the tissue side of the suture. 
         [0037]    The invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying illustrative drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]      FIG. 1A  is a perspective view of a suture anchor in an undeployed configuration; 
           [0039]      FIG. 1B  is a perspective view of the suture anchor shown in  FIG. 1A  in a deployed configuration; 
           [0040]      FIGS. 2A and 2B  are sectional views of the suture anchor and insertion instrument shown in  FIGS. 1A and 1B  respectively; 
           [0041]      FIG. 3A  is a proximal end view of a body component of a suture anchor; 
           [0042]      FIG. 3B  is a sectional view of the body component taken along line  3 B- 3 B of  FIG. 3A ; 
           [0043]      FIG. 4A  is a side view of a sleeve component of a suture anchor; 
           [0044]      FIG. 4B  is a sectional view of the sleeve component taken along line  4 B- 4 B of  FIG. 4A ; 
           [0045]      FIGS. 4C and 4D  are proximal and distal end views respectively of the sleeve component shown in  FIG. 4A ; 
           [0046]      FIG. 5A  is a perspective view of a bone locking component of a suture anchor; 
           [0047]      FIG. 5B  is a side view of the bone locking component shown in  FIG. 5A ; 
           [0048]      FIG. 5C  is a sectional view of the bone locking component taken along line  5 C- 5 C of  FIG. 5B ; 
           [0049]      FIG. 5D  is a proximal end view of the bone locking component of  FIG. 5B ; 
           [0050]      FIG. 6  is an illustration of a suture anchor system including a suture anchor and multiple sutures connected thereto; 
           [0051]      FIGS. 7 and 8  are partial cross sectional views of a suture anchor inserted in a bone in and undeployed and deployed configuration respectively; 
           [0052]      FIG. 9  is a partial cross sectional view of a suture anchor inserted in a bone in a deployed configuration and with the insertion instrument withdrawn; 
           [0053]      FIGS. 10A-10D  are various views of another plug component of a suture anchor assembly; 
           [0054]      FIGS. 11A-11C  are perspective views of another suture anchor transitioning from a first undeployed configuration, to an intermediate configuration, and to a deployed or locked configuration respectively; 
           [0055]      FIG. 12  is a flowchart of the steps to deploy a suture anchor; and 
           [0056]      FIGS. 13A and 13B  are illustrations of a suture anchor in bone in an aligned position and an offset position respectively. 
       
    
    
     DETAILED DESCRIPTION 
       [0057]    Before the present invention is described in detail, it is to be understood that this invention is not limited to particular variations set forth herein as various changes or modifications may be made to the invention described and equivalents may be substituted without departing from the spirit and scope of the invention. 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 invention. 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 invention. All such modifications are intended to be within the scope of the claims made herein. 
         [0058]    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 invention. 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. 
         [0059]    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 invention (in which case what is present herein shall prevail). 
         [0060]    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. It is also 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 invention belongs. 
         [0061]    The present invention provides improved methods and devices for knotless suturing of tissue. Although the variation discussed herein discusses use of a suture, the term “suture” may include any piece of material that is used to close a wound or connect tissue (e.g., catgut, thread, wire, etc.) so long as the material can be used with the other portions of the anchor as described herein. Accordingly, sutures as described herein may include polymeric, metallic, or other types of sutures. 
         [0062]    For illustrative purposes, the examples discussed herein show the use of the anchoring system to suture soft tissue to a bone structure, namely, the humeral head. The present invention is particularly well-suited for repairing rotator cuff injuries by re-attaching the rotator cuff tendon to the outside of the humeral head. Embodiments of the present invention permit minimally invasive surgeries on such injuries and greatly facilitate rapid and secure fixation of the rotator cuff tendon to the humeral head. However, it should be understood that the same principles described herein apply to the repair of other injuries in which soft tissue is to be re-attached to a bone structure or other tissue region. For example, in embodiments, the soft labrum may be attached to the glenoid. In other embodiments, other soft or connective tissues are attached to bone bodies or other tissues as the case may be. 
         [0063]    Anchor Structure Overview 
         [0064]      FIGS. 1A and 1B  show an anchor assembly  10  for securing soft tissue to a bone with one or more sutures in an undeployed and deployed configuration respectively.  FIGS. 2A and 2B  show cross sectional views of the anchor shown in  FIGS. 1A and 1B  respectively. The anchor assembly  10  is shown comprising a plurality of components (namely, sleeve  12 , wings  14 , and body  16 ). The anchor components movably cooperate together to provide two configurations including: (a) a first undeployed configuration in which the tissue may be drawn towards the anchor by applying tension to the free ends or limbs of the suture; and (b) a second deployed configuration in which the anchor is fixed in the bone, and the suture is locked in the anchor thereby securing the tissue to the bone. 
         [0065]      FIGS. 1A and 2A  show the anchor assembly  10  in an undeployed configuration. In particular, sleeve member  12  is shown positioned proximal to wings  14 , and anchor body  16 . Wings  14  are undeformed, substantially parallel to the body  16 , and unexpanded. In this undeployed state, it can be seen that the sutures are free to slide and move through the anchor upon applying a tension to either the tissue side  20  or the free side  22  of the sutures. In particular, the suture free legs  22  may be pulled so as to pull soft tissue attached to the bound legs  20  closer to the suture anchor. 
         [0066]    Suture guide  50  may have an eyelet, groove, or slit shape. Preferably guide has a smooth surface to allow for easy suture sliding during use. Additionally, inner body  16  may have an elongate nest or groove (not shown) to provide some limitation to any lateral motion of the suture (i.e. to keep the suture from slipping off the shaft). The suture itself may also comprise a low friction material such as polyester suture to create an overall low friction environment. Examples of sutures include without limitation low friction UHMWPE suture and polyester suture. 
         [0067]    At least one suture which includes at least one bound leg  20  is shown threaded through the eyelet  50  and redirected proximally back through the lumen  51  of the instrument  30  to result in free legs  22 . The bound side or leg  20  is considered bound because in practice, this leg or limb of the suture is “bound” to the soft or connective tissues to be attached to the target tissue such as bone by virtue of passing the sutures through the connective or soft tissues using conventional suturing techniques known in the art. The free side or leg  22  is considered “free” because the surgeon or practitioner, in practice, has control over this limb or leg of the suture with his or her hands or appropriate instrumentation. 
         [0068]      FIGS. 1B and 2B  show the anchor assembly  10  in a deployed configuration. In particular, the sleeve  12  has been urged distally (e.g., pushed) by an instrument driver surface (not shown) onto the anchor body  16 . As the sleeve is urged distally onto the anchor body  16 , the outer surface of the sleeve  12  displaces wings  14 , and in particular, radially expands the wings to embed, affix, or lock the anchor assembly in a bone. 
         [0069]    The sleeve  12  also serves to lock or retain the suture. As the sleeve  12  is urged distally onto the anchor body  16 , the inner surface of the sleeve compresses the suture against the outer surface of anchor body (or plug portion)  16  of the anchor assembly. 
         [0070]    The embodiment shown in  FIG. 2B  also includes a second locking surface  54  which is off-axis, namely, not parallel to the longitudinal axis of the suture anchor body  16 . The combination of contact surfaces to compress the suture aid to lock the suture and prevent slip. The combination of contact surfaces at angles to one another creates a tortuous path, increasing frictional forces on the suture when the anchor assembly is in the deployed configuration. 
         [0071]    Additionally, in embodiments, the anchor assembly does not compress or deform the anchor body  16 , nor the sleeve  12 , and a gap (G) is present between the outer diameter of the anchor body  16  and the inner diameter of the sleeve  12 . This gap allows for multiple sutures to be snared or threaded through the anchor assembly and attached to tissue. This gap ensures each of the suture lock and the bone lock function independently and effectively regardless of the number of sutures. This is an advantage of the present invention. 
         [0072]    Anchor Body 
         [0073]      FIGS. 3A and 3B  show an anchor body or plug component  16  with the other components of the anchor assembly removed for clarity. The anchor body  16  is shown having a proximal section  42 , an elongate intermediate section  44 , and a tissue penetrating distal end section  46 . An exemplary overall length (L 1 ) of the plug component ranges from 0.55 to 0.75 inch and more preferably about 0.63 inch. 
         [0074]    The distal end section  46  preferably is adapted to pierce bone. The piercing tip may facilitate the anchor to be pounded or driven into bone with a mallet or hammer-like instrument. The shape of the tip may vary widely. It may be solid, and comprise a sharp point. A dart shape is shown in  FIG. 3B . The tip increases in diameter from the distal point at an angle (α) from the centerline ranging from about 20 to 27 degrees and preferably about 23 degrees. The distal tip  46  increases in diameter from the distal to the proximal end until a maximum diameter is reached (D 1 ) at the proximal end of the end section  46 . Preferably, D 1  ranges from 0.15 to 0.25 inch and more preferably from about 0.18 inch. However, the invention is intended only to be limited as recited in the appended claims. 
         [0075]    The distal end section  46  also shows a suture holder or guide  50  which directs one or more sutures from one side of the suture anchor to the other side as shown, e.g., in  FIGS. 1-2 . The suture guide  50  may be in the form of an aperture or opening as shown. The aperture preferably has a diameter in the range of 0.060 to 0.080 inch. Additionally, the suture guide may comprise a groove or other shape which serves to guide the sutures into and out of the anchor assembly. The suture guide preferably is smooth so as to not damage the sutures nor provide friction when the suture is being loaded or the tissue approximated as will be discussed in more detail below. 
         [0076]    The distal tip  46  may also comprise a coating or material to facilitate bone penetration. For example, the tip may be formed from a metal such as 316L stainless steel, or titanium, or a polymer such as PEEK. The anchor body including the tip may be formed of one material, or a combination of materials. In one embodiment, the anchor body is an injection molded biocompatible polymer such as PEEK. In another embodiment it is machined. Alternative embodiments may include a blunted tip for inserting into a prepared bone passage or a threaded or tissue cutting tip. 
         [0077]    The intermediate elongate section  44  is adapted to slide within and relative to the sleeve as shown in  FIGS. 1 and 2 . The elongate section  44  fits (or plugs) the sleeve member. The size of the intermediate section may vary. An exemplary diameter (D 2 ) of the intermediate section ranges from 0.090 to 0.102 inch and more preferably is about 0.100 inch. An exemplary length (L 2 ) of the intermediate section is about 0.380 to 0.420 inch and more preferably about 0.400 inch. 
         [0078]    The intermediate section  44  is shown terminating at a stop surface  48 . The stop  48  arises from the geometry of the piercing tip  46  described above, and also acts to limit distal movement of the wings  14 , and sleeve relative to the body  16 . Additionally, as described herein, the suture lengths may be compressed against stop surface  48  increasing suture locking and retention. 
         [0079]    Proximal section  42  is shown comprising a sacrificial area and means to connect to an insertion tool such as the insertion instrument  30  shown in  FIGS. 1-2 . In particular, the anchor body  16  shown in  FIG. 3B  includes a plurality of grooves  52  for receiving a threaded end of an insertion tool. Distal to the threads  52  is a weakened section  55  having a reduced diameter or thickness. As will be discussed further below, after the anchor is deployed and affixed in the bone, the insertion tool is retracted. The shaft shears or breaks away from the anchor assembly at the sacrificial region  54 . The sacrificial region is adapted to break at a tension of about 80 to 100 pounds whereas the force required to slide the sleeve over the intermediate section of the anchor body is 15 to 60 pounds. Thus, it is a sacrificial section that predictably breaks, leaving the anchor assembly properly embedded in the bone. It is also to be understood, however, that a wide range of detaching means may be employed to detach the insertion instrument from the anchor. A non-limiting example of a detachment means is an internal threaded portion within the shaft. Upon application of sufficient stress between mating threaded portions, one or both of the threaded portions strip to release the anchor from the system. Additional examples include, without limitation, a frictional press-fit or barbed coupling may be employed. The amount of force required to separate the anchor from the deployment system is sufficiently high to minimize inadvertent deployment but also to ensure that the surgeon can deploy the anchor as desired. 
         [0080]    Sleeve 
         [0081]      FIGS. 4A-4D  show a sleeve component  12  of an anchor assembly. Sleeve  12  is shown having a generally tubular shape and a lumen  62  extending from a proximal end  64  to a distal end  66  of the sleeve. The lumen is shown having a constant diameter (D 3 ). An exemplary diameter (D 3 ) for the sleeve  12  ranges from 0.105 to 0.120 inch and more preferably is about 0.108 inch. An exemplary length (L 3 ) of the sleeve ranges from 0.160 to 0.350 inch and more preferably is about 0.250 inch. 
         [0082]    As described herein, one of the functions of the sleeve is to lock the suture. In particular, sleeve coaxially surrounds a portion of the intermediate section  44  of the anchor body  16 , and compresses a suture disposed therebetween. 
         [0083]    Another function of the sleeve is to activate the bone lock or fix the anchor in the bone. The geometry of the sleeve enables bone locking. In particular, sleeve preferably has a tapered exterior. The outer diameter of the sleeve  12  increases in diameter from the distal end  66  to the proximal end  64 . The diameter (D 4 ) at the distal end may range from 0.130 to 0.150 inch and the diameter (D 5 ) at the proximal end may range from 0.150 to 0.170 inch. The transition from the smaller diameter to larger diameter may be smooth, linear, or have a radius (R 1 ). As discussed further below, urging sleeve into the bone affixation structure causes the affixation structure (e.g., the deflecting wings) to engage the bone. 
         [0084]    Deflectable Wing Members 
         [0085]      FIGS. 5A-5D  show a bone locking or affixing structure  14 . The bone locking component  14  is shown having three outwardly deflectable arms or wings  72 . The arms extend from distal end section or base  75 . The wings are separated by slots  74 . In an application, the wings  72  are deflected to engage the bone and affix the anchor therein. 
         [0086]    The bone locking structure  14  is shown having a generally tubular shape with a slight inward taper. In embodiments, and when undeployed, the outer diameter (D 7 ) of the proximal end may range from 0.150 to 0.250 inch. In embodiments, the outer diameter (D 8 ) of the distal end may range from 0.150 to 0.200 inch. Unlike the proximal end, the outer diameter of the distal end remains relatively constant and does not expand. In embodiments, the wall thickness (T) may range from 0.010 to 0.040 inch. Additionally, an exemplary overall length (L 5 ) for the bone locking structure ranges from 0.160 to 0.400 inch and more preferably is about 0.330 inch. An exemplary length (L 4 ) of the wings ranges from 0.100 to 0.350 inch and more preferably is about 0.270 inch. 
         [0087]    In embodiments, the wings  72  collectively define an inner cavity  73 . The deformable cavity  73  is sized and shaped to receive inner sleeve  12 . As sleeve  12  is pushed into the cavity  73 , the wing members  72  are forced to deflect and expand outwardly. The wing members  72  deploy and grip into the bone. 
         [0088]    The amount of deflection may be characterized by, amongst other things, the difference in outer diameter (D 7 ) of the bone locking structure between states, namely, the undeployed first state versus the deployed second state. An exemplary outer diameter (D 7 ) of the proximal end when undeployed ranges from 0.160 to 0.180 inch and more preferably is about 0.160 inch. When deployed, the outer diameter D 7  may expand to 0.240 to 0.260 inch or more. Consequently, the percent expansion in Area (A) ranges from 100 to 165%. 
         [0089]    Additionally, as mentioned above, the degree or expansion is affected by bone quality. The wings tend to expand to a greater degree in softer bone. This is an advantage over static or fixed barbed anchor designs in which the diameter of the anchoring structure is fixed/constant irrespective of the bone quality. 
         [0090]    The bone anchor structure is also shown having a base and distal aperture  75 . Distal aperture  75  is sized to cooperate with the plug component  16 . In particular, distal aperture  75  has a size and shape to receive the intermediate section  44  of the plug member  16 . The distal aperture  75  is held fixed and against stop surface  48  of the plug component  16  so that further axial movement of the wings is prohibited as the sleeve is urged into cavity  73 . 
         [0091]    The distal end opening  75  remains constant. An exemplary distal end inner diameter (D 9 ) ranges from 0.110 to 0.120 inch. 
         [0092]    The bone locking component  14  may also comprise one or more openings or windows  76  to aid in providing space or room for the sutures. For example, window  76  is sized to carry or guide multiple sutures along the anchor body towards the distal end. 
         [0093]    Barbs or ridges  80  are shown on the deflecting members  72 . The ridges serve to grip the bone tissue. The change in height (or step) of the barbs or ridges ranges from 0.030 to 0.050 inch. 
         [0094]    The illustration of the ridges is intended for example only. The suture anchor of the present invention may incorporate a number of features or structures to achieve a bone lock including, for example, assuming a larger profile using a variety of anchoring means such as expansion ribs, moly-bolts, rivets, wings, and other mechanisms. Variations are within the scope of the device and methods described herein. Additionally, variations include anchoring structures that do not fully encircle the anchor body, namely, partial or discontinuous ridges, ribs, and other structures. Also, the above mentioned size ranges and shapes are intended as exemplary only and the invention is not intended to be so limited except as recited in the appended claims. 
         [0095]    Anchor Implantation Using Instrument 
         [0096]      FIGS. 6-9  illustrate a suture anchor being implanted. As shown, sutures  28 , 29  may be previously stitched, connected to or looped through tissue  150  and loaded within anchor  132  (e.g., routed through the anchor using a snare) and instrument  128 . Instrument  128  may also have lateral aperture or opening  140 , located at the distal portion of the instrument but proximal to anchor wings  164 , operable to allow passage of sutures  28 ,  29  from the instrument to the anchor. Sutures  28 , 29  may extend distally from aperture  140  within anchor  132 , through eyelet, to the tissue  150 , and return proximally along the same path and may be connected with a portion of the instrument handle (e.g., arms  172 ), to assist in managing the sutures  28 , 29  during insertion and tensioning. 
         [0097]    The stitching process may be accomplished by any known means, and any known suture stitch may be employed. A stitch is desirably secured so that the suture is not inadvertently separated from the tendon after completion of the repair procedure, necessitating re-entry to the surgical site. In preferred approaches, the suture is attached to the soft tissue using a “mattress stitch,” which is well known in the art as being a particularly secure stitch which is unlikely to fail postoperatively. 
         [0098]    Anchor  132  may then be brought into contact against the underlying bone  100 . The bone tissue  100  may be that of a shoulder, which comprises a humeral head, including an outer cortical bone layer  167 , which is hard, and inner cancellous bone  169 , which is relatively soft. As is typically the case for rotator cuff injuries, in this instance the supraspinatus tendon  150  has become separated from the humeral head. It is desirable to reattach the tendon  150  to the humeral head. Alternative rotator cuff repair procedures are also discussed in U.S. Pat. No. 6,524,317, and entitled “Method and Apparatus for Attaching Connective Tissues to Bone Using a Knotless Suture Anchoring Device”, which is hereby incorporated by reference in its entirety. 
         [0099]    Now with reference to  FIG. 7 , the proximal end of the instrument  128  or handle  130  may be tapped, e.g., by using a mallet, to drive the suture anchor  132  into the bone at a depth of, for example, approximately 6 mm. If viewed through an arthroscope, primary anchor  132  may be driven into the underlying bone  100  until an anchor depth indicator  112  (e.g., a colored marking or gradation) is visible just above or at the bone  100 . Depth indicator  112  is a visual indicator to the user that the appropriate depth for anchor insertion has been reached. This may indicate that the anchor wings  164  have been inserted at the correct depth. Insertion to the cortical layer  167  is important to ensure anchoring structure  164 ′ gains good purchase on the bone. 
         [0100]    Next, tension is applied to the free legs  28  until the tendon  150  has been drawn toward the anchor as shown in  FIG. 8 , and is positioned for an anatomically proper repair and otherwise snugly situated with respect thereto. Non-limiting examples of threshold distances between the tissue  150  and the proximal end of the anchor range from 2-8 mm and more preferably 3-6 mm. The suture may be drawn by hand, by instrument, or a combination thereof. 
         [0101]    With suture anchor  132  at a suitable depth, and the tissue in a desired position, the anchor wings  164  may be deployed within the bone  100 , to lock the position of anchor  132  and to prevent anchor  132  from being pulled out of the bone  100 . A die or driver member (not shown) of the instrument may push sleeve  174  distally and into the cavity of the anchoring structure, deflecting the wings  164 ″ radially outward and into the bone. 
         [0102]    Such action may be carried out in a number of ways. For example, a knob  168  shown in  FIG. 6  may be linked to a driver or die member which, when turned, allows driver member to be advanced relative to the shaft. Advancing the driver member advances sleeve. The driver member may be advanced, for example, by pushing on it. Alternatively, a knob may be linked to a driver surface which is ratcheted distally, incrementally moving sleeve  174 . Handles having various actuation mechanisms for deploying anchors are described in, e.g., U.S. Patent Publication Nos. 2008/0051836; 2009/0069823; and 2010/0191283, each of which is hereby incorporated by reference in its entirety. 
         [0103]    Anchor  132  may then be released from instrument  128 , which may be achieved by a variety of mechanical means as described above. For example, the components may be operable to have a weakness or failure point that fractures or disconnects upon application of a force or torque. Some methods for this release are described in U.S. Pat. No. 6,585,730, which is hereby incorporated by reference in its entirety. Additionally, the anchor may be implanted in other manners, and without a sophisticated instrument as described above. 
         [0104]      FIG. 9  shows a deployed anchor  100  situated within the bone  100  after release from the anchoring system. A first section of the suture  182  is secured within the anchor while a second section  184  is wedged between the cavity wall and an exterior of the anchor wings  164 ″. In this variation, the suture loops from a first side of the anchor to a second side via a suture opening located in a tip portion of the locking plug. The suture is locked in several places: a) the suture is compressed between the anchor body shaft and the sleeve member; (b) the suture is compressed between the perpendicular stop surface of the body and the distal edge of the sleeve; and (c) the suture is compressed between the bone wall and the outer surface of the wing members. This so-called tri-lock provides safeguards against failure. 
       Alternative Embodiments 
       [0105]      FIGS. 10A-10D  show an alternative embodiment of a suture anchor component and in particular, an alternative embodiment of a locking plug  210 . The locking plug  210  shown in  FIGS. 10A-10D  is similar to that shown above except that tip  212  includes ridges  214 . The dimensions of the ridges are characterized by a ridge height h r  ranging from 0.005 to 0.015 inch and a ridge length l r  ranging from 0.030 to 0.050 inch. The ridges  214  aid in gripping bone as the locking plug is inserted (or pounded) into bone. 
         [0106]      FIGS. 11A-11C  show an alternative embodiment of a suture anchor assembly  300 . The anchor  300  is similar to the anchors described above except that sleeve  302  includes a ridged section  304 . With reference to  FIG. 11B , the sleeve  302  is pushed distally by a driver member  306  along anchor plug member  316 . In particular, driver  306  includes a push surface  322  which contacts proximal end of sleeve  302  to urge sleeve distally.  FIG. 11C  shows the ridged section of sleeve registered in the window  308  between the wings  312  and  314 . The ridges  304  of sleeve supplement the bone locking to secure the anchor in the bone. 
         [0107]    Methods for Securing Tissue 
         [0108]      FIG. 12  is a flowchart showing the steps of a medical procedure for securing connective tissue to bone. This procedure includes the steps of securing a bound limb of a length of one or more sutures to a portion of connective tissue (e.g., the rotator cuff tendon) to be attached to a portion of bone (e.g., the humeral head), using any method deemed suitable to the clinician (Step  410 ). 
         [0109]    Step  420  states to load the length of suture through a suture anchor device. The suture anchor device may be temporarily attached to an insertion instrument shaft distal end, having an opening to provide a passage for the length of suture to gain access to the suture anchor device as described herein. The shaft distal end may also have a driver to deploy an anchoring element, disposed at the proximal end of the anchoring device. 
         [0110]    Next, the suture anchor is inserted into a portion of bone, deep enough so that the anchor device proximal end is in the cancellous bone region. A marker or indicator may be present on the shaft distal end to aid in proper anchor placement. This step may be performed by hammering or pounding in the anchor with a mallet ( 430 ). 
         [0111]    Step  440  states to apply tension to the free end of the length of suture so as to draw the bound limb of the length of suture toward the suture anchor device, thereby drawing the connective tissue closer to the anchor. The free end of the suture is drawn until the portion of connective tissue is snugly secured to the portion of bone. 
         [0112]    The free suture ends may then be tied to a portion of the handle (or otherwise managed) to maintain tension for the next step. 
         [0113]    Step  450  states to deploy the bone locking structure. This is preferably performed by pushing on the sleeve component with a driver of the insertion instrument so as to urge the sleeve into the annular space or cavity formed between the anchor plug component and the bone anchoring structure. The wings of the bone anchoring structure are deflected radially outward (flare outward) and into the tissue. 
         [0114]    In embodiments, step  450  simultaneously locks the suture and detaches the inserter from the anchor body. In particular, the sleeve compresses the suture against the plug member, thereby locking the suture. The distal end of the sleeve pushes against stop surface  48  of the anchor body  16  causing the anchor body to detach along at a predetermined region such as engineered notch  55 . In embodiments, an engineering notch between the anchor body and the end of the insertion instrument shaft breaks or shears at a predetermined force which is greater than the force necessary to deploy the sleeve. 
         [0115]    Step  460  states to retract the insertion device. This may be carried out manually or semi automatically. First, the free ends of the suture are disconnected from the handle. Then, the handle is withdrawn. 
         [0116]    In embodiments, the sacrificial region between the anchor plug and the end of the insertion instrument shaft breaks or shears at a predetermined force which is less than the force necessary to pull out the embedded anchor. 
         [0117]    The suture ends may then be trimmed close to the proximal end of the embedded anchor. 
         [0118]      FIGS. 13A and 13B  show another anchor  510  deployed in a bone. The anchor is shown having an offset or tilt angle (β). The tissue side of the sutures  512  engage the anchor  510  at the distal end section, namely, the distal tip eyelet  514 . Tension, applied to the tissue or bound side of the sutures, induces a shift or off-axis force to the anchor (rather than pull out the anchor axially). The angle or degree of toggle (Beta) desirably ranges from 0 to 15 degrees and more preferably is between 5 and 10 degrees. Tension on the bound suture limb may be applied manually by the surgeon, or may result from exercise and use of the tendon post operation. 
         [0119]    Without being bound to theory, the toggle or tilt from the first position  520  to the second position  522  is different than most other anchors having the sutures extend through and down the center of the anchor. When the sutures extend down the center of the anchor, tension from the tissue (or repeated use of the tissue) acts to pull out the anchors. In the present embodiment shown in  FIGS. 13A and 13B , tension or strain on the anchor acts to toggle or tilt the anchor, further embedding the anchor in the bone. 
         [0120]    Although an exemplary embodiment of the invention has been shown and described, it is to be understood that all the terms used herein are descriptive rather than limiting, and that many changes, modifications, and substitutions may be made by one having ordinary skill in the art without departing from the spirit and scope of the invention. In particular, it is noted that the procedures, while oriented toward the arthroscopic repair of the rotator cuff, are applicable to the repair of any body location wherein it is desired to attach or reattach soft tissue to bone, particularly using an arthroscopic procedure.