Abstract:
An innovative bone anchor and methods for securing connective tissue, such as tendons, to bone, which permit a suture attachment that lies entirely beneath the cortical bone surface. Advantageously, the suturing material between the connective tissue and the bone anchor is secured without the need for tying a knot. The suture attachment to the bone anchor involves the looping of a length of suturing material around a self-locking wedge block in the anchor, thereby avoiding an eyelet connection which requires a kot and which concentrates stress on a very small portion of the suturing material. Thus, failure rates are greatly decreased over conventional techniques, and the innovative procedures are significantly easier to perform than conventional techniques.

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 the rotator cuff to the humeral head, in order to repair the rotator cuff.  
           [0002]    It is an increasingly common problem for tendons and other soft, connective tissues to tear or to detach from associated bone. One such type of tear or detachment is a “rotator cuff” tear, wherein the supraspinatus tendon separates from the humerus, causing pain and loss of ability to elevate and externally rotate the arm. Complete separation can occur if the shoulder is subjected to gross trauma, but typically, the tear begins as a small lesion, especially in older patients.  
           [0003]    To repair a torn rotator cuff, the typical course today is to do so surgically, through a large incision. This approach is presently taken in almost 99% of rotator cuff repair cases. There are two types of open surgical approaches for repair of the rotator cuff, one known as the “classic open” and the other as the “mini-open”. The classic open approach requires a large incision and complete detachment of the deltoid muscle from the acromion to facilitate exposure. The cuff is debrided to ensure suture attachment to viable tissue and to create a reasonable edge approximation. In addition, the humeral head is abraded or notched at the proposed soft tissue to bone reattachment point, as healing is enhanced on a raw bone surface. A series of small diameter holes, referred to as “transosseous tunnels”, are “punched” through the bone laterally from the abraded or notched surface to a point on the outside surface of the greater tuberosity, commonly a distance of 2 to 3 cm. Finally, the cuff is sutured and secured to the bone by pulling the suture ends through the transosseous tunnels and tying them together using the bone between two successive tunnels as a bridge, after which the deltoid muscle must be surgically reattached to the acromion. Because of this maneuver, the deltoid requires postoperative protection, thus retarding rehabilitation and possibly resulting in residual weakness. Complete rehabilitation takes approximately 9 to 12 months.  
           [0004]    The mini-open technique, which represents the current growing trend and the majority of all surgical repair procedures, differs from the classic approach by gaining access through a smaller incision and splitting rather than detaching the deltoid. Additionally, this procedure is typically performed in conjunction with arthroscopic acromial decompression. Once the deltoid is split, it is retracted to expose the rotator cuff tear. As before, the cuff is debrided, the humeral head is abraded, and the so-called “transosseous tunnels”, are “punched” through the bone or suture anchors are inserted. Following the suturing of the rotator cuff to the humeral head, the split deltoid is surgically repaired.  
           [0005]    Although the above described surgical techniques are the current standard of care for rotator cuff repair, they are associated with a great deal of patient discomfort and a lengthy recovery time, ranging from at least four months to one year or more. It is the above described manipulation of the deltoid muscle together with the large skin incision that causes the majority of patient discomfort and an increased recovery time.  
           [0006]    Less invasive arthroscopic techniques are beginning to be developed in an effort to address the shortcomings of open surgical repair. Working through small trocar portals that minimize disruption of the deltoid muscle, a few surgeons have been able to reattach the rotator cuff using various bone anchor and suture configurations. The rotator cuff is sutured intracorporeally and an anchor is driven into bone at a location appropriate for repair. Rather than thread the suture through transosseous tunnels which are difficult or impossible to create arthroscopically using current techniques, the repair is completed by tying the cuff down against bone using the anchor and suture. Early results of less invasive techniques are encouraging, with a substantial reduction in both patient recovery time and discomfort.  
           [0007]    Unfortunately, the skill level required to facilitate an entirely arthroscopic repair of the rotator cuff 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 rotator cuff repair, this means that the knot bundle is left in the shoulder capsule where it is able to be felt by the patient postoperatively when the patient exercises the shoulder joint. So, 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. Consequently, because of the technical difficulty of the procedure, presently less than 1% of all rotator cuff procedures are of the arthroscopic type, and are considered investigational in nature.  
           [0008]    Another significant difficulty with current arthroscopic rotator cuff repair techniques are 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.  
           [0009]    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.  
           [0010]    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, airy and somewhat vascular interior of the bone). There is a clear demarcation between the cortical bone and cancellous bone, where 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° 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.  
           [0011]    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, ostensibly locking the device into the bone.  
           [0012]    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.  
           [0013]    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.  
           [0014]    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 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.  
           [0015]    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 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.  
           [0016]    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.  
           [0017]    An approach that includes bone attachment is described in U.S. Pat. No. 5,584,835 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.  
           [0018]    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 garrot the soft tissues or increase the tension in the sutures beyond the tensile strength of the material, breaking the sutures.  
           [0019]    A disclosure that incorporates bone attachment and eliminates knot tying is set forth in U.S. Pat. No. 5,702,397 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 ostensibly 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.  
           [0020]    What is needed, therefore, is a new approach for repairing the rotator cuff or fixing other soft tissues to bone, wherein suture tension can be adjusted and possibly measured, the suture resides completely below the cortical bone surface, there is no requirement for the surgeon to tie a knot to attach the suture to the bone anchor, and wherein the procedure associated with the new approach is better for the patient, saves time, is uncomplicated to use, and easily taught to practitioners having skill in the art.  
         SUMMARY OF THE INVENTION  
         [0021]    The present invention solves the problems outlined above by providing innovative bone anchor and connective techniques which permit a suture attachment which lies entirely beneath the cortical bone surface. In the present state of the art, the sutures which are passed through the tissues to be attached to bone typically are threaded through a small eyelet incorporated into the head of the anchor and then secured by tying knots in the sutures. Endoscopic knot tying is an arduous and technically demanding task. Therefore, the present invention discloses devices and methods for securing sutures to a bone anchor without the requirement of knot tying.  
           [0022]    In one embodiment, the suture legs, after having been placed into soft tissues to be anchored to bone, are threaded through the anchor and then through a floating wedge block located at the distal end of the anchor. The wedge block is configured such that it has a hollow lumen through the center, and a conically tapered outer surface. The distal end of the wedge block is the wider end of the cone, and the transition from the inside diameter created by the hollow lumen and the outside diameter created by the conical surface includes smooth radii for dressing the sutures threaded through the hollow lumen. The sutures are passed back around the outside of the wedge block such that they rest on the conical surface. They are then re-threaded in the opposite direction back through the anchor, exiting the anchor at the proximal end thereof. The anchor is then inserted into the bone, and secured. The distal end of the anchor is tapered to match the taper of the conical surface on the wedge block. When tension is placed on the legs of the suture passing back out of the anchor, the suture is drawn through the hollow center lumen, around the distal end of the wedge block, and back out of the anchor. This tension tends to cause the wedge block to force its way back up into the anchor body, and a means to prevent this may be employed. Such means may include any structure that selectively holds the wedge block separate from the anchor body.  
           [0023]    At this juncture, by pulling on the suture legs, any slack in the sutures is removed, and the soft tissues are drawn toward the anchor. When the soft tissues are in the desired orientation, relative to the bone to which they are to be attached, the structure holding the wedge block is removed, and the back tension on the sutures pulls the wedge block into the matching taper in the anchor body, maintaining the compressive force on the suture legs.  
           [0024]    In another embodiment, the wedge block may be adapted to have a U-shaped channel along one side of the wedge, and a tapered face along the opposite side of the wedge. The U-shaped channel communicates with the tapered face via a large radius surface that transitions and blends the channel face to the tapered face. The wedge is configured such that it may be placed inside of a hollow cylinder with a tapered face that protrudes into the interior of the cylinder and is configured to mate with the taper of the wedge. The wedge is adapted to permit two legs of the suture to be threaded through the anchor body, and along the U-shaped channel to the distal end of the anchor, wherein the sutures are drawn around the radiused surface and onto the tapered surface of the wedge on the opposite side. The sutures then pass back out of the proximal end of the anchor. As before, the suture legs may pass freely around the tapered wedge block until such time as tension in the bound legs pulls the wedge block back up into the tapered body of the anchor, and locks the suture in place.  
           [0025]    Thus, with the above-described suture locking system, suture failure rates are dramatically reduced over conventional techniques because of the increased radius over which the suture is loaded, and the inventive procedures are significantly easier to perform than conventional techniques because of the elimination of knot tying.  
           [0026]    More particularly, there is provided a bone anchor device for attaching connective tissue to bone, which comprises an outer body, and a lumen extending axially through the outer body. Inner walls which define the lumen in a proximal portion of the outer body extend inwardly relative to inner walls which define the lumen in a portion of the outer body distal to the proximal portion. A wedge member is advantageously disposed in a distal end of the lumen, distal to the inwardly extending lumen wall portion, which has outer walls that taper inwardly in a proximal direction therealong. The wedge member is axially movable in the lumen distal end.  
           [0027]    In one preferred embodiment, a lumen extends axially through the wedge member, for receiving a suture therein. The wedge member preferably comprises a distal end having a curved surface, and the tapered proximal surface of the wedge member and the inwardly extending lumen internal wall together define a tapered distal lumen which communicates with the lumen.  
           [0028]    A suture extends through the lumen and around the distal curved surface of the wedge member, and includes a free end extending proximally out of the bone anchor device and a bound end attached to soft tissue to be secured to the bone, wherein when the free end is placed in tension by a proximally directed force, the suture travels about the wedge member until increased tension on the bound end causes the suture to move the wedge member axially in a proximal direction, the proximal axial travel of the wedge member continuing until the proximal surface of the wedge member has moved into sufficient proximity to the inwardly extending internal lumen wall to pinch a length of the suture in the tapered distal lumen.  
           [0029]    In another aspect of the invention, there is provided a bone anchor device for attaching connective tissue to bone, which comprises an outer body and a lumen extending axially through the outer body. Inner walls which define the lumen taper in a proximal portion of the outer body extend inwardly relative to inner walls which define the lumen in a portion of the outer body distal to the proximal portion. A suture clamping member, consisting of a wedge member, is axially movable in the lumen.  
           [0030]    In still another aspect of the invention, there is provided a bone anchor device for attaching connective tissue to bone, which comprises an outer body having a lumen extending axially therethrough. Inner walls which define the lumen in a proximal portion of the outer body extend inwardly relative to inner walls which define the lumen in a portion of the outer body distal to the proximal portion. A suture clamping member comprising a wedge member is axially movable in the lumen distal portion. A suture extends through the lumen and around a distal surface of the wedge member, which includes a free end extending proximally out of the bone anchor device and a bound end attached to soft tissue to be secured to the bone. When the free end is placed in tension by a proximally directed force, the suture travels about the wedge member until increased tension on the bound end causes the suture to move the wedge member axially in a proximal direction, the proximal axial travel of the wedge member continuing until the proximal surface of the wedge member has moved into sufficient proximity to the inwardly extending internal lumen wall to pinch a length of the suture therebetween.  
           [0031]    In another aspect of the invention, there is provided a bone anchor device for attaching connective tissue to bone, which comprises an outer body having an open distal end, and a lumen extending axially through the outer body. Inner walls which define the lumen in a proximal portion of the outer body extend inwardly relative to inner walls which define the lumen in a portion of the outer body distal to the proximal portion. A suture clamping member having an outer surface is disposed in the lumen distal end and is axially movable therein. Advantageously, complementary engaging structure is disposed on each of the suture clamping member outer surface and the lumen inner surface for retaining the suture clamping member in the lumen distal end when the bone anchor device is not in a portion of bone. This complementary engaging structure preferably comprises a pin disposed on one of the suture clamping member outer surface and the lumen inner surface, and a recess for receiving the pin disposed on the other of the suture clamping member outer surface and the lumen inner surface.  
           [0032]    In yet another aspect of the invention, there is provided a bone anchor device for attaching connective tissue to bone, which comprises an outer body having an outer surface, and a lumen extending axially through the outer body. Inner walls which define the lumen in a proximal portion of the outer body extend inwardly relative to inner walls which define the lumen in a portion of the outer body distal to the proximal portion. A suture clamping member is disposed in the lumen distal portion and is axially movable therein. Additionally, at least one outwardly extendable rib is disposed on the outer body outer surface for anchoring the outer body into surrounding bone.  
           [0033]    In still another aspect of the invention, there is provided a bone anchor device for attaching connective tissue to bone, which comprises a distal wedge anchor portion comprising an outer body having an outer surface, on which a outwardly deployable anchoring element is situated. Additionally, a proximal driver portion is connected to the distal wedge anchor portion at a proximal end thereof, which includes an actuator for deploying the anchoring element outwardly. Advantageously, the connection between the proximal driver portion and the distal wedge anchor portion is releasable once the anchoring element has been deployed. In a preferred embodiment, this is accomplished because of a designed failure point in the connection between the proximal driver portion and the distal wedge anchor portion, so that upon deployment of the anchoring element outwardly, additional force may be applied to separate the driver portion from the anchor portion so that only the driver portion may be proximally removed from the patient&#39;s body.  
           [0034]    In yet another aspect of the invention, there is disclosed a method for securing connective tissue to bone, which comprises securing a first end of a length of suture to a portion of soft tissue to be attached to a portion of bone. A second end of the length of suture is threaded through a lumen in an outer body of a bone anchor device and about an axially movable suture clamping member disposed in a distal portion of the lumen. The outer body is placed in a blind hole disposed in the portion of bone, and the second end of the length of suture is pulled proximally, so that the suture travels about the axially movable suture clamping member and draws the first end of the length of suture toward the bone anchor device, thereby securing the portion of soft tissue snugly to the portion of bone. Advantageously, when the tension on the first end of the length of suture increases, as the portion of soft tissue is bound to the portion of bone, the suture clamping member is pulled proximally toward inwardly extending walls defining a portion of the lumen, thereby clamping a portion of the length of suture between the inwardly extending lumen walls and the suture anchoring device.  
           [0035]    Additional steps in the preferred method include anchoring the outer body in the blind hole, preferably by deploying ribs disposed on an outer surface of the outer body to an outwardly extended position, into surrounding cancellous bone, and cutting a portion of the suture second end to complete the procedure.  
           [0036]    In another aspect of the invention, there is disclosed a method for securing connective tissue to bone, which comprises securing a first end of a length of suture to a portion of soft tissue to be attached to a portion of bone, and threading a second end of the length of suture through a lumen in an outer body of a bone anchor device and about an axially movable suture clamping member disposed in a distal portion of the lumen. The bone anchor device is inserted into a blind hole disposed in the portion of bone, and a deployable anchoring member disposed on an outer surface of the outer body is extended outwardly to secure the bone anchor device in surrounding bone. Following this step, a driver portion of the bone anchor device is separated from the outer body and withdrawn from the patient&#39;s body. Then, the second end of the length of suture is pulled proximally, to secure the portion of soft tissue properly to the portion of bone and to anchor the suture in the outer body by moving the suture clamping member axially to a suture clamping position.  
           [0037]    In still another aspect of the invention, there is provided a bone anchor device for attaching connective tissue to bone, which comprises a body having a longitudinal axis, a distal end, and a proximal end. A surface on the body distal end slopes inwardly toward the longitudinal axis from a distal portion of the surface toward a proximal portion thereof. A suture anchoring member which is movable axially toward and away from sloping surface forms a part of the bone anchor device. The suture anchoring member s a distal end surface and opposing axial surfaces, wherein the distal end and opposing axial surfaces all comprise suture receiving surfaces for contacting suture material wrapped thereabout. In essence, this means that in use, a length of suture material will be wrapped about the suture anchoring member in such a manner that the length of suture material will be in physical contact with all of the distal end surface and opposing side surfaces. In preferred embodiments, one of the opposing axial surfaces is sloped so that a width of the suture anchoring member (i.e. a dimension of the suture anchoring member which is transverse to the longitudinal axis) tapers from a distal end to a proximal end thereof.  
           [0038]    As has been discussed supra, the sloped axial surface and the inwardly sloped body distal end surface together define a tapered distal lumen.  
           [0039]    Now, it is to be understood that the above described invention is particularly suited to locking sutures that have been passed through soft tissues and are to be anchored to bone. The creation of an anchor point within the bone is outside the scope of this invention, although many alternative methods of anchoring suture to bone are contemplated. For example, some currently preferred methods are discussed in U.S. patent application Ser. No. 09/616,802, entitled Method &amp; Apparatus for Attaching Connective Tissues to Bone Using a Suture Anchoring Device, filed on Jul. 14, 2000. The referenced application is commonly assigned with the present application, and is incorporated by reference in its entirety herein. Other prior art anchors, such as screws, moly bolts, and pop rivets may be adapted for use with the present invention as well.  
           [0040]    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 drawing.  
         BRIEF DESCRIPTION OF THE DRAWINGS  
         [0041]    [0041]FIG. 1 is a cross-sectional view of one embodiment of a portion of a bone anchor having a suture lock constructed in accordance with the principles of the present invention;  
           [0042]    [0042]FIG. 2 is a plan view of a second embodiment of a bone anchor having a suture lock similar to that shown in FIG. 1;  
           [0043]    [0043]FIG. 2A is a cross-sectional view taken along lines  2 A- 2 A of FIG. 2;  
           [0044]    [0044]FIG. 2B is a view taken along lines  2 B- 2 B of FIG. 2;  
           [0045]    [0045]FIG. 3 is a plan view similar to that of FIG. 2, illustrating a first step in a preferred method for using the embodiment of FIG. 2;  
           [0046]    [0046]FIG. 3A is a cross-sectional view taken along lines  3 A- 3 A of FIG. 3;  
           [0047]    [0047]FIG. 3B is a distal end view taken along lines  3 B- 3 B of FIG. 3;  
           [0048]    [0048]FIG. 4 is a plan view similar to that of FIG. 3, illustrating a second step in a preferred method for using the embodiment of FIG. 2;  
           [0049]    [0049]FIG. 4A is a cross-sectional view taken along lines  4 A- 4 A of FIG. 4;  
           [0050]    [0050]FIG. 4B is a distal end view taken along lines  4 B- 4 B of FIG. 4;  
           [0051]    [0051]FIG. 5 is a plan view similar to those of FIGS. 3 and 4, illustrating a third step in a preferred method for using the embodiment of FIG. 2;  
           [0052]    [0052]FIG. 5A is a cross-sectional view taken along lines  5 A- 5 A of FIG. 5;  
           [0053]    [0053]FIG. 6 is a plan view similar to those of FIGS.  3 - 5 , illustrating a fourth step in a preferred method for using the embodiment of FIG. 2;  
           [0054]    [0054]FIG. 6A is a cross-sectional view taken along lines  6 A- 6 A of FIG. 6;  
           [0055]    [0055]FIG. 6B is a view taken along lines  6 B- 6 B of FIG. 6;  
           [0056]    [0056]FIG. 6C is a cross-sectional view of one type of suture material which may be used in the present invention;  
           [0057]    [0057]FIG. 6D is a cross-sectional view illustrating the suture of FIG. 6C after it has been clamped and compressed by the wedge clamp of the present invention;  
           [0058]    [0058]FIG. 7 is a plan view similar to those of FIGS.  3 - 6 , illustrating a fifth step in a preferred method for using the embodiment of FIG. 2;  
           [0059]    [0059]FIG. 8 is a schematic view illustrating a first step in a preferred method for using a suture lock and bone anchor constructed in accordance with the present invention to repair a tom rotator cuff arthroscopically;  
           [0060]    [0060]FIG. 9 is an enlarged schematic view illustrating the distal end of the instrument shown in FIG. 8;  
           [0061]    FIGS.  10 - 14  are views similar to FIG. 9 illustrating sequential steps in the aforementioned method; and  
           [0062]    [0062]FIG. 15 is a schematic view similar to FIG. 8 illustrating the repaired rotator cuff at the conclusion of the aforementioned method. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0063]    Referring now more particularly to the drawings, there is shown in FIG. 1 a bone anchor  10  constructed in accordance with an embodiment of the present invention, comprising a body  12  which includes threads  14  on an outside surface thereof, a proximal lumen  16 , and a tapered distal lumen  18  that communicates with the proximal lumen  16 . A wedge body  20  includes a tapered end  22  and a lumen  24  through the wedge body  20 . The lumen terminates in a large blend radius  26  at the distal end of the wedge body  20 . A suture  28  which includes a bound leg  30  and a free leg  32  is threaded through the proximal lumen  16  and the wedge body lumen  24 , passes around the large blend radius  26 , and is redirected back through the proximal lumen  16 . The bound leg  30  is considered bound because in practice, this leg of the suture is “bound” to the soft tissues to be attached to bone by virtue of passing the sutures through the tissues using conventional suturing techniques known in the art. The free leg  32  is considered “free” because the surgeon, in practice, has control over this leg of the suture with his or her hands.  
         [0064]    In operation, as the surgeon pulls on the free leg  32  of the suture  28 , the bound leg  30  of the suture follows through the bone anchor until such time as the tissues binding in the bound leg  30  of the suture  28  creates a tension in the suture  28 . At this point, tension in the suture  28  tends to urge the wedge body  20  up into the tapered distal lumen  18 , pinching the suture  28  between the tapered distal lumen  18  and the tapered end  22  of the wedge body  20 . As the tension in the bound leg  30  of the suture  28  increases, the force on the wedge body  20  increases. In turn, the pinching force on the suture  28  also increases, creating a self-locking mechanism. The threads  14  on the exterior surface of the body  12  function to secure the bone anchor in surrounding bone material.  
         [0065]    Referring now to FIGS. 2, 2A, and  2 B, a second modified embodiment of the inventive bone anchor device  110  is illustrated, wherein like elements to those shown in FIG. 1 are designated by like reference numerals, preceded by the numeral “1”. The bone anchor device  110  comprises a distal wedge anchor portion  135  and a proximal driver portion  137 , which are secured together mechanically in a coaxial arrangement by crimped segments  139  or other suitable means. As in the FIG. 1 embodiment, the distal wedge anchor portion  135  includes a body  112  which comprises a proximal lumen  116 , a tapered distal lumen  118 , and a wedge body  120  having a tapered end  122  and a large blend radius  126 . A pin  141  may be disposed in a groove  142  on the wedge body  120 , which is complementary to a groove  143  on an interior surface of the body  112  of the distal wedge anchor portion  135 . When the pin  141  is disposed in the groove  142  and the groove  143 , it functions as a retainer to keep the wedge body  120  in position in the distal lumen  118  of the device  110 . This arrangement is particularly convenient when there is no suture threaded through the device, so that the device, though formed of separable elements, tends to remain unitary, thereby easing the already complicated job of the practitioner performing the repair procedure.  
         [0066]    A crimped flat  145  on the surface of the distal portion of the body  112  creates the progressive proximal tapering in the tapered distal lumen  118 , discussed supra in connection with the FIG. 1 embodiment, which is important to ensure that the suture becomes pinched between the wedge body  120  and the interior surface of the bone anchor body  112  in the tapered distal lumen  118  as the wedge body  120  moves proximally under tension, as will be described more fully hereinbelow.  
         [0067]    Also on the outer surface of the body  112  of the bone anchor portion  135  are a plurality of slots  147 , which are distributed in a spaced configuration about the entire circumference of the cylindrical body  112 . These slots  147  are illustrated as being disposed at an acute angle with respect to a longitudinal axis  149  of the instrument  110 , although in other preferred embodiments the slots are oriented parallel to the axis  149 . Such slots and their function are more fully described in U.S. patent application Ser. No. 09/616,802, which has already been expressly incorporated herein by reference. Their function will also be described in greater detail hereinbelow.  
         [0068]    Now with reference in particular to FIGS.  3 - 7 , a method for using the bone anchor device  110  of FIGS. 2, 2A, and  2 B to secure soft tissue to bone, for example, will be described. Initially, a suture  128 , and particularly a bound leg  130  of the suture  128 , is stitched in a suitable manner to a portion of soft tissue  151 , such as a tendon, which is to be secured to a bone (not shown). The stitching process may be accomplished by any known means, and any known suture stitch may be employed, the objective being to ensure a secure stitch so that the suture is not inadvertently separated from the tendon after completion of the repair procedure, necessitating reentry 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. Of course, as discussed supra, the preferred repair procedure discussed herein is an arthroscopic procedure, wherein an initial access incision is made to the repair site, such as a shoulder, and a trocar is inserted into the access incision to provide access to the repair site for surgical instruments as well as optical instruments. Preferably, a suturing instrument is inserted into the trocar to perform the aforementioned suturing step. Of course, the inventive devices may also be utilized in an open surgical procedure, if desired, wherein the sutures are manually placed.  
         [0069]    Once the suturing process is completed, a free end  132  of the suture  128  is removed proximally through the trocar from the patient&#39;s body, together with the suturing instrument. The free end  132  of the suture is then threaded through a lateral port  153  and then through the proximal lumen  116  of the bone anchor instrument  110  (FIGS. 3, 3A, and  3 B). It is threaded distally through the tapered distal lumen  118  and around the distal end surface (large blend radius)  126  of the wedge body  120 , then proximally back through the tapered distal lumen  118  and through the lumen  116  to the proximal end of the driver portion  137 . It is noted that, in this embodiment, the wedge body  120  does not include a wedge lumen, as in the FIG. 1 embodiment. Rather, the suture is threaded about the wedge body, so that it is in physical contact with the large blend radius  126 , as well as with each opposing side surface  154   a, b  (FIG. 4A) of the wedge body. However, the wedge body could be modified to include a wedge lumen, and the suture could be threaded therethrough, as in the FIG. 1 embodiment, if desired.  
         [0070]    Once the threading process is completed, the bone anchor instrument  110  is returned through the trocar (not shown) to the repair site, and the distal wedge anchor portion  135  is placed into a blind hole (not shown) which has been made, preferably by drilling, into the bone to which the soft tissue  151  is to be secured.  
         [0071]    With reference now to FIGS. 4, 4A, and  4 B, once the distal wedge anchor portion  135  is satisfactorily disposed within the bone (not shown), the driver portion is actuated to radially outwardly deploy a plurality of ribs  157  which comprise the portions of the body  112  which lie between the aforementioned spaced slots  147 . This procedure is more fully described in co-pending U.S. patent application Ser. No. 09/616,802, already incorporated herein by reference, but, essentially, the deployment is made by axially compressing the distal wedge anchor portion to thereby force the ribs  157  radially outward. In a preferred embodiment, wherein, as mentioned supra, the slots  147  lie at an angle with the longitudinal axis  149  of the device  110 , the resulting “petals” formed by the radially outwardly extending ribs  157  take on a semi-circular shape, with the “petals” overlapping one another to create an extraordinarily strong anchor body. The soft cancellous bone into which the anchor body is radially extended tends to flow between the “petals” as well, further strengthening the achieved anchoring effect both axially and radially. The anchor should be radially deployed beneath the cortical bone surface, so that it is virtually impossible to retract the distal wedge anchor portion from the bone proximally past the cortical outer surface thereof without breaking the native bone.  
         [0072]    A unique and important feature of the present invention is the provision of a stress point  159  in the junction between the distal wedge anchor portion  135  and the proximal driver portion  137 . The reason for this is that, once the driver portion has been utilized to position the wedge anchor portion, and then actuated to axially compress the wedge anchor portion, so that the anchor ribs  157  are radially extended, there is no more purpose for the driver portion. As mentioned supra, the wedge anchor portion  135  and driver portion  137  are mechanically joined by, for example, a plurality of crimped segments  139 , which create an interfering fit between the axially overlapping cylindrical bodies of each of the two portions  135 ,  137 . Of course, many other equivalent joinder means may be employed as well, and these means will be well known to those of ordinary skill in the art. In the presently preferred embodiment, however, the stress point  159  is co-located with the crimped segments  139 , and designed so that, as the compressing force is applied by the driver portion  137  to the wedge anchor portion  135 , to radially deform and extend the ribs  157 , when it reaches a level somewhat above the force level required to complete the anchor deployment, the stress point which is a pre-designed point of weakness or “failure point”, will break, physically separating the driver portion  137  from the anchor portion  135 . FIGS. 5 and 5A illustrate the device  110  after the driver portion  137  has been separated from the wedge anchor portion  135  and withdrawn proximally from the patient&#39;s body through the trocar (not shown).  
         [0073]    Thus, the wedge anchor portion  135  is now permanently deployed in the bone, to thereby securely anchor the suture  128  therein, and thus permanently secure the soft tissue  151  to the bone.  
         [0074]    With reference now to FIGS. 6, 6A, and  6 B, it will be seen that, once the distal anchor portion  135  is secured within the bone, it is time for the practitioner to pull the free ends  132  of the suture  128  proximally, to draw the soft tissue  151  toward the bone until it is snugly situated in desired proximity thereto, thereby creating a tight and secure connection between the soft tissue and the bone. As discussed supra, with respect to the FIG. 1 embodiment, the bound leg  130  of the suture follows through the bone anchor, about the wedge body  120 , until such time as the tissues  151  binding in the bound leg  130  of the suture  128  create a tension in the suture  128 . This will occur when the soft tissue  151  has been drawn toward the bone and is snugly situated with respect thereto. At this point, tension in the suture  128  tends to urge the wedge body  120  proximally, up into the tapered distal lumen  118 , as shown in FIG. 6A, pinching the suture  128  between an inwardly sloping surface  161  (FIG. 4A) on the body  112  and the sloping axial surface  154   a  on the tapered end  122  of the wedge body  120 , within the tapered distal lumen  118 . As the tension in the bound leg  130  of the suture  128  increases, the proximal force on the wedge body  120  increases. In turn, the pinching force on the suture  128  also increases, creating a self-locking mechanism.  
         [0075]    It may be helpful to discuss in some detail this self-locking suture mechanism. One of the significant advantages of this mechanism is its reversibility; i.e. its ability to permanently lock the bound end of the suture in position, but to permit continued adjustability of the suture loop by applying a tensile force to the free end of the suture. This is important, because a practitioner will often find that, during the course of a procedure, after the tendon/soft tissue  151  has been brought into what is believed to be a desired position relative to the bone to which it is being secured, and the suture has been locked into place to retain the tendon in that orientation, a further adjustment is necessary or desired to optimize the outcome. Using existing prior art solutions, though, wherein the suture is knotted into position and fixed at a particular length, it would be necessary to either forego the desired adjustment or, alternatively, to cut the suture and resuture the tendon. In some instances, it may be necessary to abandon the suture anchor, leaving the useless (and expensive) anchor in position, and locating a new anchor in the bone to re-suture the tendon.  
         [0076]    On the other hand, in the present invention, after the free end  132  has been pulled, as described above, sufficiently that a tension is created in the bound end  130  (due to approximation of the tendon  151  to the bone), and the suture  128  has been clamped in the tapered distal lumen  118 , only the bound end  130  is anchored in a fixed position. This ensures that the tendon is not movable relative to the bone after completion of the procedure, which, of course, is desirable. On the other hand, the free end  132  continues to be movable, to thereby permit adjustment of the size of the suture loop through the tendon  151 , which in turn permits adjustment or “fine tuning” of the position of the tendon  151  with respect to the bone.  
         [0077]    To understand this advantageous feature, it may be helpful to review in a bit more detail the functionality of the inventive device and method. Again with reference to FIGS.  2 - 6 B, it may be seen that, in the early procedural steps, both the free and bound suture legs are freely movable to slide the suture  128  about the free-floating anchor wedge  120 . However, once tension develops in the bound leg  130  as the tendon  151  approximates the bone, the wedge  120  is pulled proximally to clamp a length of the suture  128  within the tapered distal lumen  118 , as discussed in detail supra. Applying a tensile force to the bound leg at this juncture only enhances the clamping effect by proximally pulling the wedge  120  even more tightly against the clamped length of suture  128 . FIGS. 6C and 6D illustrate the effect of this clamping force on the clamped length of suture  128 , as observed by the inventor. In the case where #2 round suture is utilized, having a cross-sectional width of 0.023 inches, as shown in FIG. 6C, the clamping force exerted by the wedge block  120  against the clamped length of suture causes it to flatten and compress to a width of approximately 0.011 inches.  
         [0078]    On the other hand, now the free leg  132  of the suture  128  may continue to be manipulated to adjust the size of the suture loop at the bound end. Applying a tensile force to the free leg  132 , once the suture is clamped by the wedge  120 , causes the wedge  120  now to move again in a distal direction, thereby increasing the cross-sectional area of the tapered lumen  118 , so that the clamped length of suture may slide to adjust the positioning of the bound suture end. There are two apparent reasons for this response. One is that, when the free end  132  is pulled, the clamped length of suture  128  wants to straighten out, so that it pushes against the angled inner lumen wall which forms, in part, the tapered distal lumen  118 . Since this wall is fixed in position, a reactive force pushes against the tapered face of the wedge  120 , pushing it a modest distance distally. Another reason is that continued tension on the free end of the suture results in a return of the cross-sectional area of the clamped suture portion from a reduced flat cross-section to the original larger round cross-section. This rounding effect reduces the surface contact of the suture with the adjacent lumen walls (and resultant frictional interface), making it easier for the suture to slide through the tapered lumen. Also, the increased suture diameter pushes the wedge  120  a slight distance distally. The resultant larger tapered lumen permits free sliding of the suture  128  until a desired adjustment has been made, after which the tendon  151  is again clamped as explained supra.  
         [0079]    Now referring to FIG. 7, the final step in the sequence of permanently anchoring the soft tissue  151  to bone is illustrated, wherein, once the suture is locked in place by virtue of the proximal positioning of the wedge body  120  within the anchor portion  135 , the free end  132  is cut off near the proximal end of the anchor portion  135 , and the incision is closed. The free end  132  is only cut off after all final adjustments have been made, as discussed above, so that the tendon is precisely positioned as desired.  
         [0080]    FIGS.  8 - 15  illustrate a procedure similar to that shown in FIGS.  2 - 7 , but specifically adapted for repair of a patient&#39;s rotator cuff, arthroscopically. Accordingly, like elements to those illustrated in previous figures will be designated by the same reference numerals, preceded by the numeral “2”.  
         [0081]    Thus, there is shown in FIG. 8 a shoulder  261 , which comprises a humeral head  263 , including an outer cortical bone layer  265 , which is hard, and inner cancellous bone  267 , which is relatively soft. As is typically the case for rotator cuff injuries, in this instance the supraspinatus tendon  251  has become separated from the humeral head  263 , and the objective of the rotator cuff repair procedure is to reattach the tendon  251  to the humeral head  263 .  
         [0082]    Alternate rotator cuff repair procedures are also discussed in co-pending U.S. patent application Ser. No. 09/475,495, filed on Dec. 30, 1999, and entitled Method and Apparatus for Attaching Connective Tissues to Bone Using a Knotless Suture Anchoring Device, which is herein expressly incorporated by reference.  
         [0083]    To effect the rotator cuff repair, the practitioner will first create an incision in the patient&#39;s shoulder  261 , into which will be inserted a trocar  269 , as shown in FIG. 8. The trocar permits access to the procedural site for visualization instruments, as well as working instruments, and permits the procedure to be completed arthroscopically.  
         [0084]    Again, as in the embodiment shown in FIGS.  3 - 7 , once the trocar has been inserted, the first procedural step is to suture the tendon  251 , using desired techniques which are beyond the scope of this patent application, creating a bound suture end  230  (FIGS. 8 and 9). Once this suturing step is completed, as with the FIGS.  3 - 7  embodiment, the free end  232  (FIG. 9) of the suture  228  is removed proximally through the trocar from the patient&#39;s body, together with the suturing instrument (not shown). The free end  232  of the suture is then threaded through the proximal lumen  216  of the bone anchor instrument  210  through a lateral port  253 , distally through the tapered distal lumen  218  and around the large blend radius  226  of the wedge body  220 , then proximally back through the tapered distal lumen  218  and through the lumen  216  to the proximal end of a driver portion  237 . Once the threading process is completed, the bone anchor instrument  210  is returned through the trocar  269  to the repair site, and the distal wedge anchor portion  235  is placed into a blind hole  271  which has been made, preferably by drilling, into the bone  263  to which the soft tissue tendon  251  is to be secured.  
         [0085]    With reference now to FIG. 10, once the distal wedge anchor portion  235  is satisfactorily disposed within the bone  263 , beneath the cortical layer  265 , the driver portion  237  is actuated to radially outwardly deploy a plurality of ribs  257  to create a “flower” comprised of a plurality of “petals”, which have a diameter substantially larger than the diameter of the hole  271 , thereby preventing “backout” of the anchor portion  235  from the hole  271 . Although many different actuation mechanisms may be employed, the illustrated embodiment shows a handle portion  273  (FIG. 8) including a trigger  275 , which may be squeezed by the practitioner to axially compress the anchor portion  235  and thereby deploy the “flower” anchor. This procedure is the same as that employed in the FIGS.  3 - 7  embodiment.  
         [0086]    As in the FIGS.  3 - 7  embodiment, a stress point  259  is provided in the junction between the distal wedge anchor portion  235  and the proximal driver portion  237 . Referring now to FIG. 11, then, as in the prior embodiment, once the wedge anchor portion has been fully compressed to fully radially extend the anchor ribs  257 , the trigger  275  continues to be squeezed for a period of time to exert continuing axial compression force on the column of the wedge anchor portion  235 . This continued force application will cause the column to fail at its designed failure point, namely, the stress point  259 , so that the driver portion  237  becomes physically separated from the anchor portion  235 . As shown in FIG. 11, once the driver portion  237  is physically separated from the anchor portion  235 , it is withdrawn proximally through the trocar  269 , out of the patient&#39;s body. In FIG. 11, the driver portion  237  is shown partially withdrawn, and in FIG. 12 it is fully withdrawn. It is noted that, in this embodiment, a suture channel  277  is disposed coaxially about the driver portion  237 , as shown.  
         [0087]    Thus, the wedge anchor portion  235  is now permanently deployed in the bone  263 , to thereby securely anchor the suture  228  therein, and thus permanently secure the soft tissue  251  to the bone  263 .  
         [0088]    With reference now to FIGS. 12 and 13, it will be seen that, once the distal anchor portion  235  is secured within the bone  263 , it is time for the practitioner to pull the free end  232  of the suture  228  proximally, to draw the tendon  251  toward the bone  263  until it is snugly situated in desired proximity thereto, thereby creating a tight and secure connection between the tendon and the bone. As discussed supra, with respect to prior embodiments, the bound leg  230  of the suture follows through the bone anchor, about the wedge body  220 , until such time as the tendon  251  binding in the bound leg  230  of the suture  228  creates a tension in the suture  228 . At this point, tension in the suture  228  tends to urge the wedge body  220  proximally, up into the tapered distal lumen  218 , as shown in FIG. 12, pinching the suture  228  between the tapered distal lumen  218  and the tapered end  222  of the wedge body  220 . As the tension in the bound leg  230  of the suture  228  increases, the proximal force on the wedge body  220  increases. In turn, the pinching force on the suture  228  also increases, creating a self-locking mechanism.  
         [0089]    Now referring to FIG. 13, once the suture  228  is locked in place within the bone anchor portion  235 , the suture channel  277  is proximally withdrawn through the trocar  269 . Then, as shown in FIGS. 14 and 15, the excess suture material on the free leg  232  is cut off, the trocar is removed, and the incision is closed to complete the procedure.  
         [0090]    Accordingly, 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.