Abstract:
A bone anchor and methods for securing soft tissue, such as tendons, to bone, permits a suture attachment that lies entirely beneath the cortical bone surface. The suturing material between the soft tissue and the bone anchor is secured without the need for tying a knot, thus avoiding what is, for arthroscopic procedures, an extremely demanding and difficult task. A knotless anchor for fixation of soft tissues to bone includes a bone lock in the form of a screw, and a suture lock in the form of a plug which is movable into a lumen.

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 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.  
         [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 the reluctance of physicians 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. 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 greatly compromised.  
         [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]     The use of screws for the creation of the attachment point in the bone is well known in the art. Two patents among many that illustrate the broad application of screw shaped constructs are U.S. Pat. No. 5,851,219 to Goble et al and U.S. Pat. No. 6,117,162 to Schmieding et al. These two patents focus on particular aspects of suture anchors such as self tapping threads, or the shape of the threads, or a particular shape or configuration of the driving means. A common feature of these two patents, and indeed the majority of patents in the art of bone screw anchors is the inclusion of an eyelet for accommodation of the suture.  
         [0021]     A screw anchor that does not use an eyelet is disclosed in U.S. Pat. No. 5,571,139 to Jenkins, Jr. wherein a cannulated or hollow screw anchor is disclosed. This anchor uses a stepped internal channel that will accommodate lengths of suture, but is small enough not to allow a knot placed in the suture to migrate through the anchor. Although this anchor does not use an eyelet, it still requires the creation of knots in the suture to lock the tissues in place.  
         [0022]     Another screw anchor patent that discloses a knotless approach is U.S. Pat. No. 6,159,235 to Kim. One of the unique features of this anchor is the ability to rotate the anchor body to insert the screw while keeping the suture from wrapping up around the anchor. However, in looking at the embodiment described, a couple of problems are clear. The suture clamping area due to the geometry required by the ring and journal construction is somewhat limited, and it is expected that construction would cause a stress riser in the suture such that the suture would consistently break at the ring at a relatively low tension. Also, because the screw needs to be driven further into the bone in order to lock the suture, tension on the cuff will be increased as the screw is tightened. Although it may be that the locking ring and journal may be massaged to accomplish reasonable knot pull strength, the issue of tension is unavoidable. It may be mitigated with training and experience, but the fact remains that excess tension would be a common failure mode.  
         [0023]     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 anchor 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  
       [0024]     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.  
         [0025]     In particular, the present invention includes further improvements to the novel suture locking mechanism disclosed in co-pending U.S. patent application Ser. No. 09/781,793, entitled Method &amp; Apparatus for Attaching Connective Tissues to Bone Using a Knotless Suture Anchoring Device, filed on Feb. 12, 2001, and presently allowed. The referenced application is commonly assigned with the present application, and is expressly incorporated by reference in its entirety herein.  
         [0026]     As previously discussed, knot tying in arthroscopic procedures is an extremely demanding and difficult task. Elimination of this step in the performance of, for example, an arthroscopic rotator cuff repair, while still showing the advantages of using suture for attachment to the cuff, streamlines and simplifies the procedure. Advantageously, therefore, a knotless anchor is disclosed for fixation of soft tissues to bone, including a bone lock in the form of a screw, as well as a suture tensioning mechanism and a suture locking mechanism.  
         [0027]     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 utilizing a screw construct is within 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. Pat. No. 6,582,453, and in U.S. Pat. No. 6,547,800. The referenced patents are both commonly assigned with the present application, and are expressly incorporated by reference, each in their entirety, herein. Other prior art anchors, such as moly bolts, and pop rivets may be adapted for use with the present invention as well.  
         [0028]     More particularly, there is disclosed a knotless suture anchor apparatus for anchoring a length of suture with respect to a body cavity. This apparatus comprises an anchor body having an anchoring structure for fixing the anchor body within a body cavity. The anchoring structure comprises a threaded surface which is rotatable to engage adjacent bone. A suture tensioning mechanism for accommodating and tensioning the length of suture is also provided. Additionally, a suture locking mechanism for locking the length of suture in place, once it has been tensioned to a desired level, forms a part of the disclosed apparatus.  
         [0029]     Preferably, the threaded surface is disposed on a distal end of the anchoring structure, and the anchoring structure further comprises a shaft extending proximally from the threaded surface. The proximal end of the shaft is connected to a handle. The shaft preferably comprises an inner, tubular shaft, and the anchoring structure further comprises an outer shaft disposed about the inner shaft. The outer shaft is proximally removable from its position disposed about the inner shaft after the threaded surface is engaged in the adjacent bone.  
         [0030]     It should further be noted that the suture tensioning mechanism is structurally integrated with the anchoring structure, and is deployed after the threaded surface is engaged in the adjacent bone and after portions of the anchoring structure have been withdrawn. A snare loop is preferably employed for snaring the length of suture and threading it through the suture tensioning mechanism. Moreover, the suture tensioning mechanism comprises a rotatable knob which is operably connected to a ratchet and pawl system. The suture locking mechanism comprises a locking lever for actuating a rotatable cable capture plate.  
         [0031]     In another aspect of the invention, there is disclosed a knotless suture anchor apparatus for anchoring a length of suture with respect to a body cavity, which comprises an anchor body having a screw-type anchoring structure for fixing the anchor body within a body cavity. The screw-type anchoring structure comprises a threaded surface on a distal end thereof which is rotatable to engage adjacent bone, wherein the anchoring structure further comprises a shaft extending proximally from the threaded surface. A handle is connected to a proximal end of the shaft. The apparatus further comprises a suture tensioning mechanism for accommodating and tensioning the length of suture, and a suture locking mechanism for locking the length of suture in place once it has been tensioned to a desired level.  
         [0032]     In still another aspect of the invention, there is disclosed a method of securing soft tissue with respect to a body cavity without knots, which comprises a step of passing a length of suture through soft tissue so that a loop of suture material is embedded in the soft tissue resulting in two free ends, and a second step of threading the two free ends of the length of suture through an anchor body. The method further comprises an additional step of engaging a distal end of the anchor body with adjacent bone to fix the anchor body in place within the body cavity, tensioning the length of suture to approximate the soft tissue to the bone as desired; and locking the length of suture in position after it has been tensioned as desired.  
         [0033]     In a preferred approach, the threading step includes snaring the length of suture. Moreover, a portion of the anchor body is removed after the engaging step.  
         [0034]     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  
       [0035]      FIG. 1A  is a partial sectional view through the left shoulder of a human as seen from the front showing the use of a minimally invasive soft tissue to bone attachment system of the present invention;  
         [0036]      FIG. 1B  is an enlarged sectional view taken within the circle denoted  1 B in  FIG. 1A ;  
         [0037]      FIGS. 2A-2D  are enlarged sectional views of the use of the soft tissue to bone attachment system of  FIG. 1A  to reattach a rotator cuff tendon;  
         [0038]      FIG. 3  is a perspective view of one embodiment of a suture anchoring device constructed in accordance with the principles of the present invention;  
         [0039]      FIG. 4  is a perspective view from the opposite side of the device shown in  FIG. 3 , with portions removed to illustrate a first step in the inventive method;  
         [0040]      FIG. 5  is a perspective view similar to  FIG. 4 , illustrating a second step in the inventive method;  
         [0041]      FIG. 6  is a perspective view similar to  FIG. 5 , illustrating a third step in the inventive method;  
         [0042]      FIG. 7  is a cross-sectional view of the device shown in  FIGS. 3-6 , illustrating further details of its construction;  
         [0043]      FIG. 8  is a partial perspective view of a distal section of the handle portion of the device shown in  FIGS. 3-7 , illustrating constructional details of the suture tensioning system;  
         [0044]      FIG. 9  is a perspective view of the entire handle portion of the device shown in  FIGS. 3-8 , illustrating a first step for tensioning the suture;  
         [0045]      FIG. 10  is a perspective view similar to  FIG. 9 , illustrating a second step for tensioning the suture;  
         [0046]      FIG. 11  is a perspective view similar to  FIG. 10 , illustrating a third step for tensioning the suture;  
         [0047]      FIG. 12  is a perspective view of the device shown in  FIGS. 3-11 , illustrating a step of completing the inventive procedure by removing the bone anchor applying and suture tensioning mechanism from the procedural site;  
         [0048]      FIG. 13  is a perspective view of a second embodiment of a suture anchoring device constructed in accordance with the principles of the present invention;  
         [0049]      FIG. 14  is a perspective view of the embodiment of  FIG. 13 , illustrating a first step in the inventive method;  
         [0050]      FIG. 15  is a perspective view of the embodiment of  FIGS. 13 and 14 , after the bone anchoring device has been removed, illustrating suture management techniques in accordance with the invention;  
         [0051]      FIG. 16  is a perspective view of the embodiment of  FIGS. 13-15 , after a suture tensioning apparatus has been introduced into the procedural site;  
         [0052]      FIG. 17  is a top view of the suture tensioning mechanism of the embodiment of  FIGS. 13-16 ;  
         [0053]      FIG. 18  is a perspective view of the embodiment of  FIGS. 13-17 , illustrating a suture tensioning step of the invention;  
         [0054]      FIG. 19  is a perspective view of the suture tensioning mechanism of  FIG. 17 ;  
         [0055]      FIG. 20  is a perspective view of the embodiment of  FIGS. 13-19 , illustrating a further suture tensioning step of the invention;  
         [0056]      FIG. 21  is a perspective view similar to  FIG. 20  of the embodiment of  FIGS. 13-20 , illustrating yet a further suture tensioning step of the invention;  
         [0057]      FIG. 22  is a perspective view similar to  FIG. 21  of the embodiment of  FIGS. 13-20 , illustrating a final suture tensioning step of the invention;  
         [0058]      FIG. 23  is a perspective view of an implant adapted to be delivered by the mechanisms described above;  
         [0059]      FIG. 24  is a perspective view of the implant of  FIG. 23 , from a different orientation; and  
         [0060]      FIGS. 25A, 25B , and  25 C are cross-sectional views, taken sequentially, of the implant shown in  FIGS. 23 and 24 , illustrating the functional aspects of the structure. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0061]     The present invention provides an improved knotless suture anchor apparatus for anchoring a length of suture with respect to a body cavity. In the exemplary embodiment described herein, the apparatus is used to anchor a length of suture to a bone structure, specifically the humeral bone of the human shoulder. The length of suture is desirably looped through soft tissue, such as a rotator cuff tendon, to approximate and fix the soft tissue with respect to the body cavity (e.g., bone structure). It should be understood, however, that the suture anchor apparatus may be utilized to secure a length of suture to body cavities other than in a bone structure, and may even be used to anchor the suture outside of a body cavity, merely to a predetermined location within the body. In this regard, the preferred apparatus includes an anchor body within which the length of suture may be anchored without knots. If the anchor body is to be implanted within the body cavity, a screw anchor is provided for securing the anchor body therein.  
         [0062]     As mentioned, 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. The invention permits minimally invasive surgeries on such injuries and greatly facilitates rapid and secure fixation of the rotator cuff tendon to the humeral head. 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.  
         [0063]      FIGS. 1A-1B  and  2 A- 2 D are cross-sectional views through the left shoulder of a human as viewed from the front and illustrate the use of an exemplary suture anchor system  20  for repairing a rotator cuff tendon injury. The rotator cuff tendon  22  is shown in its natural position overlying the bulbous humeral head  24  of the humerus bone  26 . In rotator cuff injuries, the tendon  22  partially or completely separates from its attachment point to the humeral head  24 , which point of attachment is typically located along an angled shelf, the greater tuberosity  28 . In minimally invasive surgeries to repair the rotator cuff injury, the surgeon threads one or more sutures through the rotator cuff tendon  22  and anchors them to the greater tuberosity  28 . The suture anchor system  20  of the present invention facilitates this latter step of anchoring the sutures to the greater tuberosity  28 .  
         [0064]     With reference first to  FIG. 1A , a generally tubular trocar  30  provides a conduit through the soft tissue of the shoulder for the suture anchor system  20  of the present invention. Typically, the surgeon makes an incision or stab wound through the outer dermal layers of sufficient size to permit passage of the trocar  30  through skin and the deltoid muscle into proximity with the humeral head  24 . Various trocars and techniques for creating the approach passageway are known and may be utilized with the present invention. In addition, more than one incision and conduit may be necessary to perform the several suturing and anchoring steps.  
         [0065]     After establishing one or more direct conduits to the humeral head  24 , the surgeon passes a length of suture through the soft tissue of the rotator cuff tendon  22  so that a loop  32  of suture material is embedded therein, as seen in  FIG. 1B . The two free ends  34   a ,  34   b  of the length of suture are withdrawn from the patient and coupled to the suture anchor system  20 . The specifics of this coupling and subsequent manipulation of the two free ends of the suture will be described more fully below. For the purpose of explaining the exemplary method of use, it is sufficient to understand that the two free ends  34   a ,  34   b  pass into a lumen at the distal end of the suture anchor system  20  and extend through the lumen in a proximal direction to a proximal end of the system to enable fixation or pulling of the suture ends. As seen in  FIG. 1B , the two free ends  34   a ,  34   b  are shown projecting from a proximal end of the system.  
         [0066]     The exemplary system  20  as illustrated is particularly suitable for anchoring a suture to a body cavity, specifically the humeral head  24  as shown. When anchoring sutures to such a bone structure, a conventional technique is to first form a blind hole or cavity  40  through the cortical layer  42  and into the soft cancellous matter  44 , as seen in  FIGS. 1A-1B  and  2 A- 2 D. The surgeon then inserts a suture anchor  46  into the cavity  40  and screws it in such that it cannot be removed from the cavity.  
         [0067]     The suture anchor  46  performs two functions: anchoring itself within the body cavity and anchoring the sutures therein. In the disclosed embodiment, the former function is accomplished using a screw-type anchoring structure  48  ( FIG. 3 ) located on the distal end of the suture anchor  46 . The anchoring structure  48  will be described in more detail hereinbelow, but briefly, it functions to retain the suture anchor  46  within the cavity  40 . In this manner, the suture anchor  46  is prevented from being removed from the cavity  40  by the anchoring structure  48 . The present invention illustrates a particular anchoring structure  48 , although any similar expedient will work.  
         [0068]     The second function of the suture anchor  46  is the anchoring or fixation of the suture with respect to the suture anchor itself, without the use of knots. Desirably, the particular manner of anchoring the suture with respect to the suture anchor  46  permits easy adjustment of the length of suture between the suture anchor and the loop  32  formed in the soft tissue. This adjustment allows the surgeon to establish the proper tension in the length of suture for effective repair of the soft tissue; reattachment of the rotator cuff tendon  22  in the illustrated embodiment. In this regard,  FIG. 2D  shows the fully deployed suture anchor  46  after the free ends  34   a ,  34   b  have been placed in tension and locked within the suture anchor. Although not shown, the remaining steps in the procedure involve withdrawing the tube from the surgical site and severing the free ends  34   a ,  34   b  close to the suture anchor  46 .  
         [0069]     Now, with reference especially to  FIGS. 3-12 , a first embodiment of the present invention will be described. In  FIG. 3  there is shown a suture anchoring device  50  which comprises a handle actuator  52  attached to an outer tubular shaft  54 . An inner tubular shaft  55  is disposed within the outer tubular shaft  54 . The screw-type anchor  48  is attached to a distal end of the inner shaft  55 . The handle actuator  52  is adapted for both inserting the bone anchor  48  and for tensioning the suture  34 , using suture cinching knob  56 , in a manner to be discussed below.  
         [0070]     Now with reference in particular to  FIG. 4 , the handle actuator  52  is illustrated. The device  50  is located as desired within the blind hole or cavity  40  in the bone  26  ( FIGS. 1-2 ). Then, a screw-type anchoring structure  48  is turned to become fixedly engaged with the bone  26 . The screw-type anchoring structure  48  comprises a distal pointed end  84  and a proximal shaft  86 , on the surface of which are a plurality of threads  88 , such that the structure  48  resembles a conventional screw. To fixedly engage the structure  48  and the bone  26 , therefore, the practitioner locates the anchoring structure  48  so that the distal end  84  is directly adjacent to the desired bone anchoring location. The handle  52  is then rotated in a clockwise direction, causing the attached shafts  54 ,  55  and screw shaft  86  to follow, so that the anchor  46  is advanced into the bone as the threads  88  are engaged therein. The mechanism is similar to that by which a screwdriver is rotated to engage a wood screw into a piece of wood. In the course of turning the anchor  46 , a slot  72 , which serves to allow the suture  32  to exit the interior of the shaft  54 , is aligned so that the slot  72  is facing the tissue to be repaired.  
         [0071]     The handle actuator  52  comprises a snare tab  58 , to which is secured a snare loop  60 , which is actually more visible in  FIG. 5 . The next step in the procedure, once the suture loop  32  has been attached to the soft tissue  22 , is to thread the suture  32  through the device  50 . To accomplish this, the free ends  34   a ,  34   b  of the suture loop  32 , which is attached to the soft tissue  22  (not shown in  FIG. 4 ), are threaded through the snare tab  58  and attached snare loop  60  in a downward direction illustrated by the arrow  62 . Then, as shown in  FIG. 5 , the snare tab  58  is lifted upwardly in a direction illustrated by arrow  64  to also lift upwardly an attached snare  66 , which is connected to the snare tab  58 . As shown in  FIG. 6 , the snare  66  and snare loop  60  are pulled in a generally upward and proximal direction illustrated by arrow  68 , thus pulling the suture free ends  34   a ,  34   b  into the lumen  70  of the tubular shaft  55  and down into the suture anchor  46 . Further, by pulling on the snare  66 , the suture ends  34  are pulled back out of the suture anchor.  
         [0072]     As noted by viewing  FIGS. 5-7 , the suture  32  is disposed within a lumen  70  ( FIG. 7 ) in the inner tubular shaft  55 . A slot  72  in the outer shaft  54 , and a like slot in the inner shaft  55  (not shown), allow the suture  32  to be threaded into the suture anchor  46 . The suture then extends proximally through the handle actuator  52 , as shown, within an upper slot  74 , which is continuous with the slot  72 , as shown in  FIG. 5 . A suture anchor insertion knob  76  is disposed on the handle actuator  52 , and includes a slot  80 , which is arranged to align with the slots  72  and  74 . Thus, the continuous slots  72 ,  80 , and  74  permit ready insertion of the suture  32  into the lumen of the tube  55  and the interior of the handle actuator  52 , as shown particularly in  FIG. 7 .  
         [0073]     In  FIG. 7 , which is a cross-sectional view illustrating the path of the suture  32  through the device  50 , it can be seen that the suture cinching knob  56  ( FIG. 6 ) is operatively connected to a suture cinch wheel  82 , through which the suture  32  is disposed. The suture cinching function will be described in more detail hereinbelow.  
         [0074]     Now, with the suture anchoring device fixedly anchored within the bone cavity  40  by means of the above described engagement of bone anchor  46  and adjacent bone  26 , and further with the suture attached to the soft tendon  22 , and threaded through the suture anchoring device  50 , the practitioner is free to tension the suture  32  as desired in order to approximate the tendon  22  to the adjacent bone.  
         [0075]      FIG. 8  illustrates the suture cinching mechanism which forms a part of the handle  52 . As discussed above, opposed suture cinching knobs  56  operate together to actuate the cinch wheel  82  ( FIG. 7 ) and an associated ratchet  90  and ratchet pawl  92 . To cinch the suture  32  about the cinch wheel  82 , the cinching knobs  56  are rotated in a clockwise direction, as illustrated by the arrow  94 . As the ratchet  90  is rotated in concert with the cinching knobs  56 , thus cinching the suture in order to tension it and therefore approximate the tendon  22  to the bone  26 , the pawl  92  sequentially engages each tooth  96  on the ratchet  90  to prevent the ratchet from reversing. When the suture is cinched to a desired level, the pawl  92 , through its engagement with a then corresponding tooth  96 , will maintain the suture cinching mechanism in the desired position, to maintain the suture tension.  
         [0076]     Now with particular reference to  FIGS. 7 and 9 - 11 , there are illustrated, in sequence, structure and steps for locking the suture in place once it has been tensioned to a desired level, as described above. The handle  52  comprises at its proximal end a recess  98  which extends entirely therethrough and is open on both sides. As shown particularly in  FIG. 9 , a suture locking mechanism  100  is disposed within the recess  98 . The suture locking mechanism  100  comprises a rotatable cable capture plate  102 , which rotates responsive to the actuation of a rotatable suture locking lever  104 . A suture lock cable  106  extends into the recess  98 , as shown, and has a stop member  108  disposed on its proximal end. The suture lock cable  106  extends distally through the handle  52  and the lumen  70  of the tubular shaft  55 , as shown in  FIG. 7 . It is attached at its distal end to the bone anchor  48 . To lock the suture  32  in place, the suture locking lever  104 , which is normally stowed in a closed position against the handle  52 , as shown, for example, in  FIG. 3 , is released and rotated in the direction indicated by an arrow  110  ( FIG. 9 ). Rotation of the suture locking lever  104  results in a corresponding rotation of the cable capture plate  102 . As shown in  FIG. 10 , the lever  104  continues to be rotated about the handle  52 , in the direction of arrow  112 , so that the cable capture plate  102  rotates as well, to the position shown, wherein it is distal to the stop member  108 . When the lever  104  is fully circumferentially rotated, once again to its closed position against the handle  52 , the cable capture plate  102  is engaged with the stop member  108 , as shown in  FIG. 11 , to lock the cable  106  in place.  
         [0077]     The action of locking the cable  106  in place, as illustrated in  FIG. 11 , functions to place the cable in tension, wherein it tends to move toward the center of the lumen  70  ( FIG. 7 ).  
         [0078]     Once the suture is locked in place, the practitioner can remove the apparatus  50 , including all but the inner shaft  55 , by depressing a ratchet release button  114  ( FIGS. 8 and 12 ), and withdrawing the handle  52  proximally.  
         [0079]     A second embodiment of the inventive apparatus is illustrated in  FIGS. 13-22 . In this embodiment, a primary difference is that separate bone anchor and suture tensioning devices are utilized. Thus, as shown in  FIGS. 13 and 14 , there is provided a bone anchor installation tool  114 , which comprises a handle  116 , a shaft  118  extending distally from the handle  116 , and a screw-type bone anchor  120  disposed on a distal end of the shaft  118 . A suture lock cable  122  having a stop member  124  disposed on a proximal end thereof extends from the proximal end of the handle  116 . A snare loop  126  and a length of suture  128  are both attached to the bone anchor  120  and extend proximally through the shaft  118  and handle  116 , as illustrated. As in the prior embodiment, the anchor  120  is located adjacent to a desired bone location, within the bone cavity  40  ( FIGS. 1-2 ), and the handle  116  is rotated in a clockwise fashion to insert the bone anchor  120  into the adjacent bone. Then, the suture loop  32 , previously attached to the soft tissue  22 , is threaded through the shaft  118 .  
         [0080]     Once the bone anchor  120  is disposed in the desired bone, the device  114  is withdrawn from the procedural site, as shown in  FIG. 15 , leaving only the bone anchor  120  and attached suture  128 , snare loop  126 , and cable  122 , as shown, wherein the suture loop  32  from the soft tissue  22  is disposed in the snare loop  126 . The next step in the inventive procedure is to tension the suture loop  32 , as desired, to approximate the soft tissue  22  to the bone  26 . In order to accomplish the tensioning step, a suture tensioning apparatus  130  is inserted into the procedural site, and engaged with the suture  32 , as shown in  FIG. 16 . The apparatus  130  comprises a handle portion  132 , and a tensioning device  134 , which comprises a housing  136  and suture cinching knobs  138 . Distally of the suture tensioning housing  136  is a tubular shaft  140  having a slot  142  on an upper end thereof. The suture  32  and cable  122  are inserted into the tubular shaft through the slot  142 , as shown.  FIG. 17  shows the tensioning device  134  from the top, wherein the suture loop  32  has been inserted into the housing  136 , through an accommodating aperture  144 .  
         [0081]     As shown in  FIG. 18 , the cable  122  has been extended proximally from a proximal end of the suture tensioning housing  136 , through a cylinder  146 , and then through a post  148  which is disposed on a first handle  150  of the handle portion  132 . As can be seen by a comparison of  FIGS. 16 and 18 , the first handle  150  has been pivotably moved apart from a second handle  152  in  FIG. 18 , to permit the post  148  to be in alignment with the cable  122 .  
         [0082]      FIG. 19  illustrates the same housing  136  as is illustrated in  FIG. 17 , but one of the tensioning knobs.  138  has been removed in  FIG. 19  for clarity, thereby revealing a suture tensioning mechanism  154  which is very similar to that employed in the embodiment of  FIGS. 3-12 , including, for example, a ratchet  156  and a ratchet pawl  158 . As shown, the suture  32  has been threaded through the suture tensioning mechanism  154 , about a suture cinch wheel (not shown), in much the same manner as in the first embodiment. Once the suture has been tensioned, as desired, using the suture cinching knobs  138 , in the same manner as in the prior embodiment, then, as shown in  FIG. 21 , the handle  150  is pivoted downwardly to a location adjacent to the handle  152 , thereby pulling the cable  122  proximally, and causing it to clamp the suture  32  within the shaft  140 , between the cable  122  and lumen walls, as is the case with the prior embodiment. Then, as shown in  FIG. 22 , the device  130  may be withdrawn from the procedural site.  
         [0083]     The figures above illustrate the delivery and actuation mechanisms associated with the installation and deployment of a specially designed implant for fixation of soft tissues to bone. This unique implant has been adapted to a screw body for excellent holding power in soft cancelleous bone. Although there are many features of this implant that are similar to that disclosed in U.S. patent application Ser. No. 09/781,793, already incorporated by reference in the present application, there are new features specific to the suture locking mechanism that will be described by referring to the figures below.  
         [0084]     Referring now to  FIGS. 23 and 24 , there may be seen a knotless suture anchor  168  similar in structure to suture anchor  46  in  FIG. 1B , comprising an anchor body  170 , a lumen  172  through anchor body  170 , screw threads  174 , suture locking plug  176 , and suture lock cable  178 . The suture anchor  170  further comprises a nose  180 , pulley  182 , which is disposed in holes  184   a, b,  and a hex drive  186 . As previously described, the hex drive  186  is used to screw the suture anchor  168  into, for instance, bone for the purpose of creating a suture attachment point. The screw threads  174  accomplish the task of retaining the suture anchor  168  in the cancelleaous portion of the bone, although the threads may also bear upon the underside of the cortical surface.  
         [0085]     The suture locking plug  176  includes a tapered nose  188 , a body  190 , a tapered locking surface  192 , a weld hole  194 , and a travel stop  196 . A suture lock cable  178  is inserted into the locking plug  176  such that the distal end of the suture lock cable  178  is visible through the weld hole  194 . These two structures, the suture lock cable  178  and locking plug  176  may be joined together via a weld in the weld hole  194  by laser welding or other suitable means. The mechanism for joining these two structures is not critical, as they may be joined in any manner sufficient to allow the plug  176  to be pulled by the cable  178  with a force sufficient to lock sutures, and to allow the two structures to disassociate from each other to allow the deployment system to be withdrawn from the operative site. Such methods may include welding adhesive bonding, insert molding, overmolding, and similar known approaches.  
         [0086]     Referring now to  FIGS. 25A, 25B , and  25 C, there is seen a sequence of cross-sectional views of the suture anchor  168 , illustrating the suture locking function of the present invention. These figures include a suture strand  198  that is disposed in the lumen  172  and around the pulley  182 . It is to be understood that the suture strand  198  is representative of one or more suture strands that may be threaded into the suture anchor  168 , and that the structure is not limited to accepting just a single strand. In fact, in the exemplary embodiment, two strands of suture are disposed within the suture anchor  168 . However, a single strand is illustrated herein for clarity.  
         [0087]     Now with reference particularly to  FIG. 25A , there is clearance between the walls of the lumen  172  and the suture strand  198  that allow the suture strand  198  to move freely within the lumen  172  and around the pulley  182 . In this configuration, the suture may be tensioned as previously described to approximate the soft tissues to be repaired to the bone or other tissues. By pulling on the suture lock cable  178 , the locking plug  176  is forced to follow into the lumen  172 . The tapered nose  188  facilitates leading the suture locking plug  176  into the lumen  172  as the suture lock cable is pulled. It may be seen in  FIG. 25B  that the tapered locking surface  192  is in intimate contact with the suture strand  198 , and fills the lumen  172  such that a frictional lock between the lumen  172 , the plug  176 , and the suture  198  is created. The tapered locking surface  192  is tapered in order to accommodate dimensional tolerances in the diameter of the suture  198  and the lumen  172 .  
         [0088]     As may be seen by referring to  FIG. 25C , the suture lock cable is no longer attached to the plug  176 . This is a result of the frictional force created between the lumen  172 , the plug  176 , and the suture  198  overcoming the tensile strength of the attachment, for example the weld described above, between the suture lock cable  178  and the suture plug  176 . When the cable  178  and plug  176  are disassociated, the deployment means described previously may be removed from the operative site, leaving the knotless suture anchor  168  and suture  198  in place, securing the tissues. The travel stop  196  is disposed on the plug  176  to prevent the plug  176  from being pulled completely through the lumen  172  in the event that the frictional lock does not generate sufficient force to break the attachment of the suture lock cable  178  to the suture plug  176 .  
         [0089]     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.