Abstract:
Apparatus for securing an object to bone, the apparatus comprising: an anchor, the anchor comprising: a body comprising an opening for receiving a filament therein; and a locking element movably mounted to the body for selectively locking the filament to the body; and an inserter for deploying the anchor in bone, the inserter comprising: a handle; an overtube extending distally from the handle; a carriage movably mounted to the handle; a shaft movably mounted within the overtube and connected to the carriage and releasably connected to the body of the anchor, the shaft being hollow; and a rod movably mounted within the shaft and connected to the locking element.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATIONS 
       [0001]    This patent application: 
         [0002]    (1) is a continuation-in-part of pending prior U.S. patent application Ser. No. 13/830,501, filed Mar. 14, 2013 by Pivot Medical, Inc. and Jeremy Graul et al. for METHOD AND APPARATUS FOR ATTACHING TISSUE TO BONE, INCLUDING THE PROVISION AND USE OF A NOVEL KNOTLESS SUTURE ANCHOR SYSTEM (Attorney&#39;s Docket No. FIAN-8687), which patent application in turn:
       (A) is a continuation-in-part of pending prior U.S. patent application Ser. No. 13/642,168, filed Dec. 26, 2012 by Chris Pamichev et al. for METHOD AND APPARATUS FOR RE-ATTACHING THE LABRUM TO THE ACETABULUM, INCLUDING THE PROVISION AND USE OF A NOVEL SUTURE ANCHOR SYSTEM (Attorney&#39;s Docket No. FIAN-70 PCT US), which patent application in turn claims benefit of:
           (i) prior International (PCT) Patent Application No. PCT/US2011/021173, filed Jan. 13, 2011 by Pivot Medical, Inc. and Chris Pamichev et al. for METHOD AND APPARATUS FOR RE-ATTACHING THE LABRUM TO THE ACETABULUM, INCLUDING THE PROVISION AND USE OF A NOVEL SUTURE ANCHOR SYSTEM (Attorney&#39;s Docket No. FIAN-70 PCT), which in turn claims benefit of:
               (a) prior U.S. Provisional Patent Application Ser. No. 61/326,709, filed Apr. 22, 2010 by Chris Pamichev et al. for METHOD AND APPARATUS FOR RE-SECURING THE LABRUM TO THE ACETABULUM, INCLUDING THE PROVISION AND USE OF A NOVEL SUTURE ANCHOR SYSTEM (Attorney&#39;s Docket No. FIAN-55 PROV); and   (b) prior U.S. patent application Ser. No. 12/839,246, filed Jul. 19, 2010 by Chris Pamichev et al. for METHOD AND APPARATUS FOR RE-ATTACHING THE LABRUM TO THE ACETABULUM, INCLUDING THE PROVISION AND USE OF A NOVEL SUTURE ANCHOR SYSTEM (Attorney&#39;s Docket No. FIAN-4655), which in turn claims benefit of:
                   (1) prior U.S. Provisional Patent Application Ser. No. 61/271,205, filed Jul. 17, 2009 by Chris Pamichev et al. for METHOD AND APPARATUS FOR RE-SECURING THE LABRUM TO THE ACETABULUM, INCLUDING THE PROVISION AND USE OF A NOVEL NANO TACK SYSTEM (Attorney&#39;s Docket No. FIAN-46 PROV); and   (2) prior U.S. Provisional Patent Application Ser. No. 61/326,709, filed Apr. 22, 2010 by Chris Pamichev et al. for METHOD AND APPARATUS FOR RE-SECURING THE LABRUM TO THE ACETABULUM, INCLUDING THE PROVISION AND USE OF A NOVEL SUTURE ANCHOR SYSTEM (Attorney&#39;s Docket No. FIAN-55 PROV);   
                   
               
           (B) is a continuation-in-part of pending prior U.S. patent application Ser. No. 13/538,378, filed Jun. 29, 2012 by Andrew Lantz et al. for METHOD AND APPARATUS FOR RE-ATTACHING THE LABRUM TO THE ACETABULUM, INCLUDING THE PROVISION AND USE OF A NOVEL SUTURE ANCHOR SYSTEM (Attorney&#39;s Docket No. FIAN-74A), which patent application in turn claims benefit of prior U.S. Provisional Patent Application Ser. No. 61/502,621, filed Jun. 29, 2011 by Andrew Lantz et al. for FORCE-LIMITING (FORCE-CONTROLLING) DELIVERY MECHANISMS FOR THE CONTROLLED DELIVERY OF THE SUTURE ANCHOR (Attorney&#39;s Docket No. FIAN-74A PROV);   (C) claims benefit of prior U.S. Provisional Patent Application Ser. No. 61/644,129, filed May 8, 2012 by Jeremy Graul et al. for METHOD AND APPARATUS FOR RE-ATTACHING THE LABRUM TO THE ACETABULUM, INCLUDING THE PROVISION AND USE OF A NOVEL SUTURE ANCHOR SYSTEM (Attorney&#39;s Docket No. FIAN-86 PROV); and   (D) claims benefit of prior U.S. Provisional Patent Application Ser. No. 61/718,997, filed Oct. 26, 2012 by Pivot Medical, Inc. and Jeremy Graul et al. for METHOD AND APPARATUS FOR RE-ATTACHING THE LABRUM TO THE ACETABULUM, INCLUDING THE PROVISION AND USE OF A NOVEL SUTURE ANCHOR SYSTEM (Attorney&#39;s Docket No. FIAN-87 PROV); and       
 
         [0012]    (2) claims benefit of pending prior U.S. Provisional Patent Application Ser. No. 61/915,004, filed Dec. 12, 2013 by Pivot Medical, Inc. and Jeremy Graul for METHOD AND APPARATUS FOR ATTACHING TISSUE TO BONE, INCLUDING THE PROVISION AND USE OF A NOVEL KNOTLESS SUTURE ANCHOR SYSTEM (Attorney&#39;s Docket No. FIAN-102 PROV). 
         [0013]    The eleven (11) above-identified patent applications are hereby incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0014]    This invention relates to surgical methods and apparatus in general, and more particularly to surgical methods and apparatus for treating a hip joint and other anatomy. 
       BACKGROUND OF THE INVENTION 
     The Hip Joint in General 
       [0015]    The hip joint is a ball-and-socket joint which movably connects the leg to the torso. The hip joint is capable of a wide range of different motions, e.g., flexion and extension, abduction and adduction, medial and lateral rotation, etc. See  FIGS. 1A ,  1 B,  1 C and  1 D. 
         [0016]    With the possible exception of the shoulder joint, the hip joint is perhaps the most mobile joint in the body. Significantly, and unlike the shoulder joint, the hip joint carries substantial weight loads during most of the day, in both static (e.g., standing and sitting) and dynamic (e.g., walking and running) conditions. 
         [0017]    The hip joint is susceptible to a number of different pathologies. These pathologies can have both congenital and injury-related origins. In some cases, the pathology can be substantial at the outset. In other cases, the pathology may be minor at the outset but, if left untreated, may worsen over time. More particularly, in many cases, an existing pathology may be exacerbated by the dynamic nature of the hip joint and the substantial weight loads imposed on the hip joint. 
         [0018]    The pathology may, either initially or thereafter, significantly interfere with patient comfort and lifestyle. In some cases, the pathology can be so severe as to require partial or total hip replacement. A number of procedures have been developed for treating hip pathologies short of partial or total hip replacement, but these procedures are generally limited in scope due to the significant difficulties associated with treating the hip joint. 
         [0019]    A better understanding of various hip joint pathologies, and also the current limitations associated with their treatment, can be gained from a more thorough understanding of the anatomy of the hip joint. 
       Anatomy of the Hip Joint 
       [0020]    The hip joint is formed at the junction of the leg and the torso. More particularly, and looking now at  FIG. 2 , the head of the femur is received in the acetabular cup of the hip, with a plurality of ligaments and other soft tissue serving to hold the bones in articulating relation. 
         [0021]    More particularly, and looking now at  FIG. 3 , the femur is generally characterized by an elongated body terminating, at its top end, in an angled neck which supports a hemispherical head (also sometimes referred to as “the ball”). As seen in  FIGS. 3 and 4 , a large projection known as the greater trochanter protrudes laterally and posteriorly from the elongated body adjacent to the neck of the femur. A second, somewhat smaller projection known as the lesser trochanter protrudes medially and posteriorly from the elongated body adjacent to the neck. An intertrochanteric crest ( FIGS. 3 and 4 ) extends along the periphery of the femur, between the greater trochanter and the lesser trochanter. 
         [0022]    Looking next at  FIG. 5 , the hip socket is made up of three constituent bones: the ilium, the ischium and the pubis. These three bones cooperate with one another (they typically ossify into a single “hip bone” structure by the age of 25 or so) in order to collectively form the acetabular cup. The acetabular cup receives the head of the femur. 
         [0023]    Both the head of the femur and the acetabular cup are covered with a layer of articular cartilage which protects the underlying bone and facilitates motion. See  FIG. 6 . 
         [0024]    Various ligaments and soft tissue serve to hold the ball of the femur in place within the acetabular cup. More particularly, and looking now at  FIGS. 7  and  8 , the ligamentum teres extends between the ball of the femur and the base of the acetabular cup. As seen in  FIGS. 8 and 9 , a labrum is disposed about the perimeter of the acetabular cup. The labrum serves to increase the depth of the acetabular cup and effectively establishes a suction seal between the ball of the femur and the rim of the acetabular cup, thereby helping to hold the head of the femur in the acetabular cup. In addition to the foregoing, and looking now at  FIG. 10 , a fibrous capsule extends between the neck of the femur and the rim of the acetabular cup, effectively sealing off the ball-and-socket members of the hip joint from the remainder of the body. The foregoing structures (i.e., the ligamentum teres, the labrum and the fibrous capsule) are encompassed and reinforced by a set of three main ligaments (i.e., the iliofemoral ligament, the ischiofemoral ligament and the pubofemoral ligament) which extend between the femur and the perimeter of the hip socket. See, for example,  FIGS. 11 and 12 , which show the iliofemoral ligament, with  FIG. 11  being an anterior view and  FIG. 12  being a posterior view. 
       Pathologies of the Hip Joint 
       [0025]    As noted above, the hip joint is susceptible to a number of different pathologies. These pathologies can have both congenital and injury-related origins. 
         [0026]    By way of example but not limitation, one important type of congenital pathology of the hip joint involves impingement between the neck of the femur and the rim of the acetabular cup. In some cases, and looking now at  FIG. 13 , this impingement can occur due to irregularities in the geometry of the femur. This type of impingement is sometimes referred to as cam-type femoroacetabular impingement (i.e., cam-type FAI). In other cases, and looking now at  FIG. 14 , the impingement can occur due to irregularities in the geometry of the acetabular cup. This latter type of impingement is sometimes referred to as pincer-type femoroacetabular impingement (i.e., pincer-type FAI). Impingement can result in a reduced range of motion, substantial pain and, in some cases, significant deterioration of the hip joint. 
         [0027]    By way of further example but not limitation, another important type of congenital pathology of the hip joint involves defects in the articular surface of the ball and/or the articular surface of the acetabular cup. Defects of this type sometimes start out fairly small but often increase in size over time, generally due to the dynamic nature of the hip joint and also due to the weight-bearing nature of the hip joint. Articular defects can result in substantial pain, induce and/or exacerbate arthritic conditions and, in some cases, cause significant deterioration of the hip joint. 
         [0028]    By way of further example but not limitation, one important type of injury-related pathology of the hip joint involves trauma to the labrum. More particularly, in many cases, an accident or sports-related injury can result in the labrum being torn away from the rim of the acetabular cup, typically with a tear running through the body of the labrum. See  FIG. 15 . These types of labral injuries can be very painful for the patient and, if left untreated, can lead to substantial deterioration of the hip joint. 
       The General Trend Toward Treating Joint Pathologies Using Minimally-Invasive, and Earlier, Interventions 
       [0029]    The current trend in orthopedic surgery is to treat joint pathologies using minimally-invasive techniques. Such minimally-invasive, “keyhole” surgeries generally offer numerous advantages over traditional, “open” surgeries, including reduced trauma to tissue, less pain for the patient, faster recuperation times, etc. 
         [0030]    By way of example but not limitation, it is common to re-attach ligaments in the shoulder joint using minimally-invasive, “keyhole” techniques which do not require large incisions into the interior of the shoulder joint. By way of further example but not limitation, it is common to repair torn meniscal cartilage in the knee joint, and/or to replace ruptured ACL ligaments in the knee joint, using minimally-invasive techniques. 
         [0031]    While such minimally-invasive approaches can require additional training on the part of the surgeon, such procedures generally offer substantial advantages for the patient and have now become the standard of care for many shoulder joint and knee joint pathologies. 
         [0032]    In addition to the foregoing, in view of the inherent advantages and widespread availability of minimally-invasive approaches for treating pathologies of the shoulder joint and knee joint, the current trend is to provide such treatment much earlier in the lifecycle of the pathology, so as to address patient pain as soon as possible and so as to minimize any exacerbation of the pathology itself. This is in marked contrast to traditional surgical practices, which have generally dictated postponing surgical procedures as long as possible so as to spare the patient from the substantial trauma generally associated with invasive surgery. 
       Treatment for Pathologies of the Hip Joint 
       [0033]    Unfortunately, minimally-invasive treatments for pathologies of the hip joint have lagged far behind minimally-invasive treatments for pathologies of the shoulder joint and the knee joint. This is generally due to (i) the constrained geometry of the hip joint itself, and (ii) the nature and location of the pathologies which must typically be addressed in the hip joint. 
         [0034]    More particularly, the hip joint is generally considered to be a “tight” joint, in the sense that there is relatively little room to maneuver within the confines of the joint itself. This is in marked contrast to the shoulder joint and the knee joint, which are generally considered to be relatively “spacious” joints (at least when compared to the hip joint). As a result, it is relatively difficult for surgeons to perform minimally-invasive procedures on the hip joint. 
         [0035]    Furthermore, the pathways for entering the interior of the hip joint (i.e., the natural pathways which exist between adjacent bones and/or delicate neurovascular structures) are generally much more constraining for the hip joint than for the shoulder joint or the knee joint. This limited access further complicates effectively performing minimally-invasive procedures on the hip joint. 
         [0036]    In addition to the foregoing, the nature and location of the pathologies of the hip joint also complicate performing minimally-invasive procedures on the hip joint. By way of example but not limitation, consider a typical detachment of the labrum in the hip joint. In this situation, instruments must generally be introduced into the joint space using an angle of approach which is offset from the angle at which the instrument addresses the tissue. This makes drilling into bone, for example, significantly more complicated than where the angle of approach is effectively aligned with the angle at which the instrument addresses the tissue, such as is frequently the case in the shoulder joint. Furthermore, the working space within the hip joint is typically extremely limited, further complicating repairs where the angle of approach is not aligned with the angle at which the instrument addresses the tissue. 
         [0037]    As a result of the foregoing, minimally-invasive hip joint procedures are still relatively difficult to perform and hence less common in practice. Consequently, many patients are forced to manage their hip pain for as long as possible, until a resurfacing procedure or a partial or total hip replacement procedure can no longer be avoided. These procedures are generally then performed as a highly-invasive, open procedure, with all of the disadvantages associated with highly-invasive, open procedures. 
         [0038]    As a result, there is, in general, a pressing need for improved methods and apparatus for treating pathologies of the hip joint. 
       Re-Attaching the Labrum of the Hip Joint 
       [0039]    As noted above, hip arthroscopy is becoming increasingly more common in the diagnosis and treatment of various hip pathologies. However, due to the anatomy of the hip joint and the pathologies associated with the same, hip arthroscopy is currently practical for only selected pathologies and, even then, hip arthroscopy has generally met with limited success. 
         [0040]    One procedure which is sometimes attempted arthroscopically relates to the repair of a torn and/or detached labrum. This procedure may be attempted when the labrum has been damaged but is still sufficiently healthy and capable of repair. The repair can occur with a labrum which is still attached to the acetabulum or after the labrum has been deliberately detached from the acetabulum (e.g., so as to allow for acetabular rim trimming to treat a pathology such as a pincer-type FAI) and needs to be subsequently re-attached. See, for example,  FIG. 16 , which shows a normal labrum which has its base securely attached to the acetabulum, and  FIG. 17 , which shows a portion of the labrum (in this case the tip) detached from the acetabulum. In this respect it should also be appreciated that repairing the labrum rather than removing the labrum is generally desirable, inasmuch as studies have shown that patients whose labrum has been repaired tend to have better long-term outcomes than patients whose labrum has been removed. 
         [0041]    Unfortunately, current methods and apparatus for arthroscopically repairing (e.g., re-attaching) the labrum are somewhat problematic. The present invention is intended to improve upon the current approaches for labrum repair. 
         [0042]    More particularly, current approaches for arthroscopically repairing the labrum typically use apparatus originally designed for use in re-attaching ligaments to bone. For example, one such approach utilizes a screw-type anchor, with two lengths of suture extending therefrom, and involves deploying the anchor in the acetabulum above the labrum           re-attachment site. After the anchor has been deployed, one length of suture is passed either through the detached labrum or, alternatively, around the detached labrum. Then that length of suture is tied to the other length of suture so as to secure the labrum against the acetabular rim. See  FIG. 18 . 
         [0043]    Unfortunately, suture anchors of the sort described above are traditionally used for re-attaching ligaments to bone and, as a result, tend to be relatively large, since they must carry the substantial pull-out forces normally associated with ligament reconstruction. However, this large anchor size is generally unnecessary for labrum re-attachment, since the labrum is not subjected to substantial forces, and the large anchor size typically causes unnecessary trauma to the patient. 
         [0044]    Furthermore, the large size of traditional suture anchors can be problematic when the anchors are used for labrum re-attachment, since the suture anchors generally require a substantial bone mass for secure anchoring, and such a large bone mass is generally available only a substantial distance up the acetabular shelf. In addition, the large size of the suture anchors generally makes it necessary to set the suture anchor a substantial distance up the acetabular shelf, in order to ensure that the distal tip of the suture anchor does not inadvertently break through the acetabular shelf and contact the articulating surfaces of the joint. However, labral re-attachment utilizing a suture anchor set high up into the acetabular shelf creates a suture path, and hence a labral draw force, which is not directly aligned with the portion of the acetabular rim where the labrum is to be re-attached. As a result, an “indirect” draw force (also known as “eversion”) is typically applied to the labrum, i.e., the labrum is drawn around the rim of the acetabulum rather than directly into the acetabulum. See  FIG. 18 . This can sometimes result in a problematic labral re-attachment and, ultimately, can lead to a loss of the suction seal between the labrum and femoral head, which is a desired outcome of the labral re-attachment procedure. Using suture anchors of a smaller size allows the suture anchor to be set closer to the rim of the acetabulum, which can help reduce this effect. See  FIG. 18A . 
         [0045]    In addition to the foregoing, suture anchors of the sort described above require that a knot be tied at the surgical site in order to secure the labrum to the acetabulum. This can be time-consuming and inconvenient to effect. More particularly, and as noted above, the suture anchor typically has a suture connected thereto so that two lengths of suture extend from the suture anchor and are available to secure the labrum to the acetabulum (which receives the suture anchor). One or both of the two lengths of suture are passed through or around the labrum and then knotted to one another so as to secure the labrum to the acetabulum. However, it can be time-consuming and inconvenient to form the knot at the surgical site, given the limited access to the surgical site and the restricted work space at the surgical site. 
         [0046]    Accordingly, a new approach is needed for arthroscopically re-attaching the labrum to the acetabulum. 
       SUMMARY OF THE INVENTION 
       [0047]    The present invention provides a novel method and apparatus for re-attaching the labrum to the acetabulum. 
         [0048]    Among other things, the present invention provides a novel knotless suture anchor system which may be used to re-attach the labrum to the acetabulum, and/or to attach other tissue to bone. 
         [0049]    In one preferred form of the present invention, there is provided a knotless suture anchor wherein a loop of suture is passed through the labrum (or other tissue) and its two free ends are slidably connected (e.g., slidably threaded through) the knotless suture anchor. After the knotless suture anchor is advanced into the acetabulum (or other bone) and the loop of suture is tensioned so as to hold the labrum (or other tissue) in place against the acetabulum (or other bone), the knotless suture anchor is reconfigured so as to lock the loop of suture to the knotless suture anchor and hence secure the labrum (or other tissue) to the acetabulum (or other bone). 
         [0050]    In one form of the present invention, there is provided apparatus for securing a first object to a second object, the apparatus comprising: 
         [0051]    an elongated body having a distal end, a proximal end, and a lumen extending between the distal end and the proximal end, the lumen comprising a distal section and a proximal section, the distal section of the lumen having a wider diameter than the proximal section of the lumen; 
         [0052]    a window extending through the side wall of the elongated body and communicating with the lumen, the window being disposed in the vicinity of the intersection between the distal section of the lumen and the proximal section of the lumen and being sized to receive a first object therein; 
         [0053]    an elongated element extending through the lumen of the elongated body, the elongated element comprising a proximal end and a distal end; and 
         [0054]    a locking element mounted to the distal end of the elongated element and disposed in the distal section of the lumen; 
         [0055]    whereby, when the elongated body is disposed in a second object, and a first object extends through the window, and the locking element is thereafter moved proximally, proximal movement of the locking element causes the elongated body to capture the first object to the elongated body, whereby to secure the first object to the second object. 
         [0056]    In another form of the present invention, there is provided apparatus for securing a first object to a second object, the apparatus comprising: 
         [0057]    an elongated body having a distal end, a proximal end, and a lumen extending between the distal end and the proximal end; 
         [0058]    a window extending through the side wall of the elongated body and communicating with the lumen, the window being sized to receive a first object therein; 
         [0059]    a locking element disposed in the lumen, the locking element having a larger proximal end and a smaller distal end; 
         [0060]    whereby, when the elongated body is disposed in a second object, and a first object extends through the window, and the locking element is thereafter moved distally, distal movement of the locking element captures the first object to the elongated body, whereby to secure the first object to the second object. 
         [0061]    In another form of the present invention, there is provided a method for securing a first object to a second object, the method comprising: 
         [0062]    providing apparatus comprising:
       an elongated body having a distal end, a proximal end, and a lumen extending between the distal end and the proximal end, the lumen comprising a distal section and a proximal section, the distal section of the lumen having a wider diameter than the proximal section of the lumen;   a window extending through the side wall of the elongated body and communicating with the lumen, the window being disposed in the vicinity of the intersection between the distal section of the lumen and the proximal section of the lumen and being sized to receive a first object therein;   an elongated element extending through the lumen of the elongated body, the elongated element comprising a proximal end and a distal end; and   a locking element mounted to the distal end of the elongated element and disposed in the distal section of the lumen;       
 
         [0067]    extending the first object through the window; 
         [0068]    positioning the elongated body in the second object; and 
         [0069]    moving the locking element proximally, such that proximal movement of the locking element causes the elongated body to capture the first object to the elongated body, whereby to secure the first object to the second object. 
         [0070]    In another form of the present invention, there is provided a method for securing a first object to a second object, the method comprising: 
         [0071]    providing apparatus comprising:
       an elongated body having a distal end, a proximal end, and a lumen extending between the distal end and the proximal end;   a window extending through the side wall of the elongated body and communicating with the lumen, the window being sized to receive a first object therein;   a locking element mounted to the distal end of the elongated element and disposed in the lumen, the locking element having a larger proximal end and a smaller distal end;       
 
         [0075]    extending the first object extends through the window; 
         [0076]    positioning the elongated body in the second object; and 
         [0077]    moving the locking element distally, such that distal movement of the locking element captures the first object to the elongated body, whereby to secure the first object to the second object. 
         [0078]    In another form of the present invention, there is provided apparatus for securing an object to bone, said apparatus comprising: 
         [0079]    an anchor, said anchor comprising:
       a body comprising an opening for receiving a filament therein; and   a locking element movably mounted to said body for selectively locking said filament to said body; and       
 
         [0082]    an inserter for deploying said anchor in bone, said inserter comprising:
       a handle;   an overtube extending distally from said handle;   a shaft movably mounted within said overtube and releasably connected to said body of said anchor, said shaft being hollow; and   a rod movably mounted within said shaft and connected to said locking element;       
 
         [0087]    wherein at least a portion of said shaft is flexible. 
         [0088]    In another form of the present invention, there is provided apparatus for securing an object to bone, said apparatus comprising: 
         [0089]    an anchor, said anchor comprising:
       a body comprising an opening for receiving a filament therein; and   a locking element movably mounted to said body for selectively locking said filament to said body; and       
 
         [0092]    an inserter for deploying said anchor in bone, said inserter comprising:
       a handle;   an overtube extending distally from said handle;   a carriage movably mounted to said handle;   a shaft movably mounted within said overtube and connected to said carriage and releasably connected to said body of said anchor, said shaft being hollow; and   a rod movably mounted within said shaft and connected to said locking element.       
 
         [0098]    In another form of the present invention, there is provided apparatus for securing an object to bone, said apparatus comprising: 
         [0099]    an anchor, said anchor comprising:
       a body comprising an opening for receiving a filament therein; and       
 
         [0101]    an inserter for deploying said anchor in bone, said inserter comprising:
       a handle;   an overtube extending distally from said handle, wherein the distal end of said overtube is curved;   a carriage movably mounted to said handle; and   a shaft movably mounted within said overtube and connected to said carriage and releasably connected to said body of said anchor, said shaft being hollow and at least a portion of said shaft being flexible.       
 
         [0106]    In another form of the present invention, there is provided a method for securing an object to bone, said method comprising: 
         [0107]    providing apparatus comprising:
       an anchor, said anchor comprising:
           a body comprising an opening for receiving a filament therein; and   a locking element movably mounted to said body for selectively locking said filament to said body; and   
           an inserter for deploying said anchor in bone, said inserter comprising:
           a handle;   an overtube extending distally from said handle;   a shaft movably mounted within said overtube and releasably connected to said body of said anchor, said shaft being hollow; and   a rod movably mounted within said shaft and connected to said locking element;   wherein at least a portion of said shaft is flexible;   
               
 
         [0117]    forming a hole in the bone; and 
         [0118]    using the inserter to insert the anchor into the hole formed in the bone. 
         [0119]    In another form of the present invention, there is provided a method for securing an object to bone, said method comprising: 
         [0120]    providing apparatus comprising:
       an anchor, said anchor comprising:
           a body comprising an opening for receiving a filament therein; and   a locking element movably mounted to said body for selectively locking said filament to said body; and   
           an inserter for deploying said anchor in bone, said inserter comprising:
           a handle;   an overtube extending distally from said handle;   a carriage movably mounted to said handle;   a shaft movably mounted within said overtube and connected to said carriage and releasably connected to said body of said anchor, said shaft being hollow; and   a rod movably mounted within said shaft and connected to said locking element;   
               
 
         [0130]    forming a hole in the bone; and 
         [0131]    using the inserter to insert the anchor into the hole formed in the bone. 
         [0132]    In another form of the present invention, there is provided a method for securing an object to bone, said method comprising: 
         [0133]    providing apparatus comprising:
       an anchor, said anchor comprising:
           a body comprising an opening for receiving a filament therein; and   
           an inserter for deploying said anchor in bone, said inserter comprising:
           a handle;   an overtube extending distally from said handle, wherein the distal end of said overtube is curved;   a carriage movably mounted to said handle; and   a shaft movably mounted within said overtube and connected to said carriage and releasably connected to said body of said anchor, said shaft being hollow and at least a portion of said shaft being flexible;   
               
 
         [0141]    forming a hole in the bone; and 
         [0142]    using the inserter to insert the anchor into the hole formed in the bone. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0143]    These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein: 
           [0144]      FIGS. 1A-1D  are schematic views showing various aspects of hip motion; 
           [0145]      FIG. 2  is a schematic view showing bone structures in the region of the hip joint; 
           [0146]      FIG. 3  is a schematic anterior view of the femur; 
           [0147]      FIG. 4  is a schematic posterior view of the top end of the femur; 
           [0148]      FIG. 5  is a schematic view of the pelvis; 
           [0149]      FIGS. 6-12  are schematic views showing bone and soft tissue structures in the region of the hip joint; 
           [0150]      FIG. 13  is a schematic view showing cam-type femoroacetabular impingement (i.e., cam-type FAI); 
           [0151]      FIG. 14  is a schematic view showing pincer-type femoroacetabular impingement (i.e., pincer-type FAI); 
           [0152]      FIG. 15  is a schematic view showing a labral tear; 
           [0153]      FIG. 16  is a schematic view showing a normal labrum which has its base securely attached to the acetabulum; 
           [0154]      FIG. 17  is a schematic view showing a portion of the labrum detached from the acetabulum; 
           [0155]      FIG. 18  is a schematic view showing a suture anchor being used to re-attach the labrum to the acetabulum; 
           [0156]      FIG. 18A  is a schematic view showing another suture anchor being used to re-attach the labrum to the acetabulum; 
           [0157]      FIGS. 19 and 20  are schematic views showing a novel knotless suture anchor system formed in accordance with the present invention; 
           [0158]      FIGS. 21-25  are schematic views showing the knotless suture anchor of the knotless suture anchor system shown in  FIGS. 19 and 20 , and the distal end of the inserter of the knotless suture anchor system shown in  FIGS. 19 and 20 ; 
           [0159]      FIGS. 26 and 27  are schematic views showing the handle of the inserter of the knotless suture anchor system shown in  FIGS. 19 and 20 ; 
           [0160]      FIG. 28  shows portions of the knotless suture anchor system (i.e., the suture anchor, inserter and suture threader) shown in  FIGS. 19 and 20 ; 
           [0161]      FIGS. 28A ,  29  and  30  show a suture loaded into the knotless suture anchor system shown in  FIGS. 19 and 20 , wherein  FIG. 30  is a cutaway view of  FIG. 29 ; 
           [0162]      FIGS. 31-36  are schematic views showing the knotless suture anchor of the knotless suture anchor system shown in  FIGS. 19 and 20  securing a suture to bone, wherein  FIG. 36  is a cutaway view of  FIG. 35 ; 
           [0163]      FIGS. 37-48  are schematic views showing an alternative form of knotless suture anchor system formed in accordance with the present invention, wherein  FIGS. 37 ,  38 ,  41 ,  42 ,  43 ,  44 ,  47  and  48  comprise side views, and  FIGS. 39 ,  40 ,  45  and  46  comprise top views; 
           [0164]      FIGS. 49-52  are schematic views showing the knotless suture anchor system of  FIGS. 37-48  securing a suture to bone (whereby to secure a labrum to bone); 
           [0165]      FIGS. 53-56  are schematic views showing the knotless suture anchor system of  FIGS. 37-48 , wherein the shaft carrying the knotless suture anchor is formed with a flexible construction (note that suture S is omitted from  FIGS. 53-55  for the sake of clarity); 
           [0166]      FIGS. 57-71  are schematic views showing another form of knotless suture anchor system formed in accordance with the present invention, wherein the shaft is carried by a slidable inner carriage (note that in  FIGS. 66 ,  68  and  70 , the outer shell of the inserter handle is removed in order to expose internal elements of the inserter handle); and 
           [0167]      FIGS. 72-75  are schematic views showing the knotless suture anchor system of  FIGS. 57-71  deploying a knotless suture anchor in bone. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Knotless Suture Anchor System 
       [0168]    Looking first at  FIGS. 19 and 20 , there is shown a novel knotless suture anchor system  5  formed in accordance with the present invention. Knotless suture anchor system  5  generally comprises a knotless suture anchor  10 , an inserter  15  for inserting knotless suture anchor  10  in bone, and a suture threader  20  for threading a suture through knotless suture anchor  10  (and inserter  15 ) before the knotless suture anchor is deployed in bone. 
         [0169]    Looking next at  FIGS. 21-25 , knotless suture anchor  10  generally comprises a body  25 , a locking element  30  for radially expanding the body and securing a suture (not shown in  FIGS. 21-25 ) to the body, and a pull rod  35  for moving locking element  30  proximally relative to body  25 , whereby to simultaneously (i) radially expand the body so as to secure knotless suture anchor  10  to bone, and (ii) secure a suture to the body so as to secure that suture to knotless suture anchor  10  (and hence to the bone within which the knotless suture anchor is secured). 
         [0170]    More particularly, and still looking now at  FIGS. 21-25 , body  25  comprises a distal end  40  terminating in a distal end surface  45 , a proximal end  50  terminating in a proximal end surface  55 , and a stepped bore  60  extending from distal end surface  45  to proximal end surface  55 . Stepped bore  60  comprises a distal section  65  having a wider diameter, and a proximal section  70  having a narrower diameter. Distal section  65  preferably has a relatively smooth interior wall, and proximal section  70  preferably has a textured interior wall, e.g., threads  72 . A shoulder  75  is formed at the intersection of distal section  65  and proximal section  70 . 
         [0171]    Body  25  of knotless suture anchor  10  has a generally cylindrical outer surface  80  which may include ribs (or other bone-engaging elements)  85 . Ribs (or other bone-engaging elements)  85  may have various configurations, either identical to or varied from one another, and/or may be regularly or irregularly spaced, as will hereinafter be discussed. Body  25  also includes a side opening  90  which extends radially through the side wall of body  25  so as to connect stepped bore  60  with the region outside of the body  25  of knotless suture anchor  10 . Side opening  90  is preferably located in the vicinity of shoulder  75 . In one preferred form of the invention, side opening  90  extends from a region distal to shoulder  75  to a region approximately even with, or proximal to, shoulder  75 . A portion of generally cylindrical outer surface  80  is recessed as shown at  95  (i.e., to accommodate a suture extending alongside the outer surface of the body), and the proximal end  50  of body  25  is reduced in diameter as shown at  100  so as to form an annular shoulder  105 . Note that the axis of stepped bore  60  is off-center from the axis of outer surface  80  ( FIG. 25 ) so as to strengthen the side wall of body  25  at  95  while still minimizing anchor diameter. 
         [0172]    Still looking now at  FIGS. 21-25 , locking element  30  comprises an elongated body  110  having an enlarged distal end  115  which includes a thin flange  120  and terminates in a distal end surface  125 , a proximal end  130  which terminates in a proximal end surface  135 , and a stepped bore  140  which extends from distal end surface  125  to proximal end surface  135 . Note that thing flange  120  has a larger diameter than enlarged distal end  115 , and enlarged distal end  115  has a larger diameter than the portion of locking element  30  which is proximal to enlarged distal end  115 . Proximal end  130  of locking element  30  is preferably tapered, e.g., in the manner shown in  FIGS. 22 and 24 , whereby to facilitate advancement of locking element  30  into proximal section  70  of stepped bore  60  of body  25 , as will hereinafter be discussed. In one form of the present invention, proximal end  130  of locking element  30  includes a weakened section  132 , preferably formed by a circumferential groove  133 , whereby to allow the proximalmost portion of locking element  30  to separate from the remainder of locking element  30 , as will hereinafter be discussed. Stepped bore  140  comprises a distal section  145  and a proximal section  150 , with distal section  145  having a larger diameter than the diameter of proximal section  150 , and with proximal section  150  having a smaller diameter than the diameter of distal section  145 . A shoulder  155  is formed at the intersection of distal section  145  and proximal section  150 . Locking element  30  has a generally cylindrical outer surface  160  which may include ribs (or other surface profile elements)  165 . Ribs (or other surface profile elements)  165  may have various configurations, either identical to or varied from one another, and/or may be regularly or irregularly spaced, as will hereinafter be discussed. 
         [0173]    Locking element  30  is sized so that (i) the diameter of its generally cylindrical outer surface  160  is less than the diameter of distal section  65  of stepped bore  60  of body  25 , and (ii) the diameter of its flange  120  at the distal end of the locking element is larger than the diameter of distal section  65  of stepped bore  60  of body  25 , such that cylindrical outer surface  160  of locking element  30  can be received in distal section  65  of stepped bore  60  of body  25 , but flange  120  at the distal end of locking element  30  cannot normally be received in distal section  65  of stepped bore  60  of body  25 . Furthermore, locking element  30  is sized so that when its flange  120  is seated against end surface  45  of body  25 , proximal end surface  135  of locking element  30  is disposed distal to at least the proximalmost portion of side opening  90  in body  25  and, preferably, distal to the entire side opening  90  in body  25 . In one preferred form of the invention, the diameter of generally cylindrical outer surface  160  of locking element  30  is approximately equal to, or somewhat larger than, the diameter of proximal section  70  of stepped bore  60  of body  25 . As a result, when one or more sutures are disposed within distal section  65  of stepped bore  60  (i.e., when one or more sutures extend through proximal section  70  of stepped bore  60 , through distal section  65  of stepped bore  60  and out of side opening  90 , as will hereinafter be discussed), proximal movement of locking element  30  into proximal section  70  of stepped bore  60  of body  25  simultaneously causes (i) the creation of an interference fit between the generally cylindrical outer surface  160  of locking element  30 , the one or more sutures extending through proximal section  70  of stepped bore  60  and the inner wall of proximal section  70  of stepped bore  60 , and (ii) radial expansion of body  25 . Thus it will be seen that proximal movement of locking element  30  into proximal section  70  of stepped bore  60  of body  25  causes radial expansion of the body so as to secure knotless suture anchor  10  to a surrounding bone, and captures the suture within the proximal section  70  of stepped bore  60 , whereby to secure the suture to the knotless suture anchor  10  (and hence to the bone within which the knotless suture anchor  10  is secured). Furthermore, distal end  115  of locking element  30  has a diameter which is smaller than distal section  65  of stepped bore  60 , but distal end  115  of locking element  30  has a diameter which is larger than proximal section  70  of stepped bore  60 . As a result, distal end  115  of locking element  30  will stop proximal movement of locking element  30  when distal end  115  abuts shoulder  75  of body  25 . 
         [0174]    It will be appreciated that, when locking element  30  is moved proximally into proximal section  70  of stepped bore  60  of body  25 , thin flange  120  (located at the distal end of locking element  30 ) will engage distal end surface  45  of body  25  and thereafter collapse (or bend) so that thin flange  120  is able to enter distal section  65  of stepped bore  60 . By remaining engaged against distal end surface  45  of body  25  until a sufficient proximal force is applied to pull rod  35 , thin flange  120  helps to prevent the unintentional actuation of knotless suture anchor  10  by requiring the application of a force to pull rod  35  above a pre-determined threshold force (i.e., the pre-determined force at which thin flange  120  collapses, or bends) in order to permit movement of locking element  30  proximally (whereby to actuate knotless suture anchor  10 ). Note that thin flange  120  also helps secure knotless suture anchor  10  on inserter  15  during delivery of the knotless suture anchor to the surgical site. This is of significance since, unlike knotted suture anchors which are typically delivered through a guide which provides mechanical support to the knotted suture anchor during delivery, knotless suture anchors are typically delivered without the benefit of such mechanical support and hence are subjected to more forces which can dislodge the knotless suture anchor from the inserter during delivery to the bone site and into the bone hole. 
         [0175]    Looking now at  FIGS. 21-27 , pull rod  35  comprises an elongated body  170  having a distal end  175  terminating in an enlarged head  180 , and a proximal end  185  terminating within the handle  190  of inserter  15 , as will hereinafter be discussed in further detail. Elongated body  170  of pull rod  35  is sized to pass through proximal section  150  of bore  140  of locking element  30 , and enlarged head  180  of pull rod  35  is sized to seat in distal portion  145  of bore  140  of locking element  30 , such that pulling proximally on elongated body  170  of pull rod  35  will cause locking element  30  to move proximally. 
         [0176]    It should also be appreciated that enlarged head  180  of pull rod  35  comprises a proximal surface  191  which extends circumferentially around the distal end of pull rod  35  at the junction of (or transition between) elongated body  170  and enlarged head  180 . Proximal surface  191  of enlarged head  180  may comprise a fillet or chamfer, such that when a sufficient proximal force (i.e., a proximal force above a set threshold force) is applied to pull rod  35 , enlarged head  180  can move proximally into bore  140  of locking element  30 , as will hereinafter be discussed. 
         [0177]    Looking now at  FIGS. 19-27 , inserter  15  generally comprises a shaft  195  having a distal end  200  terminating in distal end surface  205 , a proximal end  210  terminating in a proximal end surface  215 , and a bore  220  extending therebetween. Distal end  200  of shaft  195  comprises a counterbore  225  which is sized so as to receive the proximal end  50  of body  25  of knotless suture anchor  10 , in a male/female connection, with distal end surface  205  of shaft  195  being seated against annular shoulder  105  of body  25 . Note that the proximal end  50  of body  25  of knotless suture anchor  10  is not round ( FIG. 25 ), and the cross-section of counterbore  225  is also not round, so as to resist twisting motions of suture anchor  10  vis-a-vis inserter  15 . A side opening  227  extends radially through the side wall of shaft  195  so as to connect bore  220  with the region outside the shaft. Preferably side opening  227  in shaft  195  is aligned with side opening  90  in knotless suture anchor  10 . 
         [0178]    The proximal end  210  of shaft  195  is secured to handle  190 . Handle  190  comprises a lever  230  which is rotatably mounted to handle  190  via a pivot pin  235 . The proximal end  185  of pull rod  35  is secured to lever  230  such that when lever  230  is activated (i.e. squeezed towards handle  190 ), pull rod  35  is moved proximally, whereby to move locking element  30  proximally, as will hereinafter be discussed. A finger-to-finger engagement is provided at  232 ,  233  so as to prevent accidental activation of lever  230 . Preferably pull rod  35  is set with a small amount of tension (that is below the threshold force that is required to retract locking element  30 ) so as to help hold suture anchor  10  on the distal end of inserter  15 . 
         [0179]    Looking next at  FIGS. 19 ,  20  and  28 , suture threader  20  is provided for threading a suture through knotless suture anchor  10  (and inserter  15 ) before the knotless suture anchor is deployed in bone. In one preferred form of the invention, suture threader  20  is pre-mounted to shaft  195  of inserter  15 , with the suture threader having a portion threaded through inserter  15  and knotless suture anchor  10  so as to facilitate threading a suture (or multiple sutures) through the knotless suture anchor  10  and through inserter  15 ; see  FIGS. 19 and 28 . More particularly, suture threader  20  preferably comprises a body  240  having clamping arms  245  extending therefrom. Clamping arms  245  are configured to releasably secure body  240  of suture threader  20  to shaft  195  of inserter  15 . A wire shaft  250  extends distally from body  240 , and a collapsible, diamond-shaped capture element  255  is secured to the distal end of wire shaft  250 . In a preferred embodiment, the wire shaft  250  and diamond-shaped capture element  255  are formed out of a single, thin Nitinol wire having its two terminal ends secured to body  240 . Prior to use, suture threader  20  has its diamond-shaped capture element  255  collapsed radially inwardly, and it is passed through side opening  227  of shaft  195 , along bore  220  of shaft  195  of inserter  15 , along proximal portion  70  of stepped bore  60  of body  25  of knotless suture anchor  10 , and out side opening  90  of body  25  of knotless suture anchor  10 , whereupon diamond-shaped capture element  255  re-expands to its erected shape, e.g., in the manner shown in  FIGS. 19 and 28 . 
       Using the Knotless Suture Anchor System to Secure Suture to Bone 
       [0180]    In use, the suture which is to be secured to a bone by means of knotless suture anchor  10  is first passed through the tissue which is to be secured to the bone, next the suture is passed through diamond-shaped capture element  255  of suture threader  20 , and then suture threader  20  is pulled rearwardly on shaft  195  of inserter  15 , towing the suture with it, until the suture has been pulled through side opening  90  of knotless suture anchor  10 , along proximal portion  70  of stepped bore  60  of body  25  of knotless suture anchor  10 , along bore  220  of shaft  195  of inserter  15 , and out side opening  227  in shaft  195  of inserter  15 . See  FIGS. 29 and 30 , which show an exemplary suture S threaded through body  25  of knotless suture anchor  10  and shaft  195  of inserter  15 . It should be appreciated that, although a single suture strand is depicted in the figures, in a preferred embodiment, two strands of suture are threaded through body  25  of knotless suture anchor  5  and shaft  195  of inserter  15 . 
         [0181]    Thereafter, and looking now at  FIGS. 29-36 , in order to secure the suture S to a bone, inserter  15  is used to advance knotless suture anchor  10  and suture S into a hole H ( FIGS. 29 and 30 ) formed in a bone B. Suture S may then be tensioned so as to adjust the position of the tissue relative to the bone. This can be accomplished by pulling on the free ends of the suture S, either independently or together. Sufficient tension will overcome any friction in the suture path and reduce the distance from the tissue to the knotless suture anchor  10  (and hence to the bone). Then the lever  230  is moved toward handle  190 , whereby to force pull rod  35  proximally. This action causes locking element  30  to move proximally ( FIGS. 31 and 32 ) so as to simultaneously (i) expand body  25  of knotless suture anchor  10  within the hole formed in the bone, whereby to secure knotless suture anchor  10  to the bone, and (ii) capture suture S between locking element  30  and the side wall of proximal portion  70  of stepped bore  60  of body  25  of knotless suture anchor  10 , whereby to secure suture S to body  25  of knotless suture anchor  10 . Further proximal movement of pull rod  35  (by way of moving lever  230  further towards handle  190 ) causes the enlarged head  180  of pull rod  35  to force its way through proximal portion  150  of stepped bore  140  of locking element  30  ( FIG. 33 ). It should be appreciated that, in order to impart a sufficient proximal force to locking element  30  so as to move locking element  30  proximally, while still permitting enlarged head  180  to force its way through bore  140  of locking element  30  when a sufficient proximal force is applied to pull rod  35 , enlarged head  180  needs to be larger in diameter than the diameter of proximal section  150  of bore  140  but not so large that it cannot be pulled through the bore  140  when sufficient proximal force is applied. It has been found that, with a bore  140  having a diameter of approximately 0.0135 inches, an enlarged head  180  having a diameter of approximately 0.0250 inches will provide adequate “interference” between enlarged head  180  and shoulder  155  so as to provide sufficient resistance to entering bore  140  when a proximal force less than the maximum proximal force (i.e., partial activation force) is applied ( FIG. 32 ). At the same time, such a configuration permits the enlarged head  180  to enter bore  140  ( FIG. 33 ) when a sufficient proximal force (i.e., full activation force) is applied to pull rod  35  (and hence to enlarged head  180 ). 
         [0182]    In other words, with the present invention, the force required to pull locking element  30  proximally so as to lock suture S to the suture anchor, and so as to expand the body of the suture anchor, is less than the force required to draw pull rod  35  through locking element  30  so as to disengage pull rod  35  from locking element  30 —this ensures that pull rod  35  is not disengaged from locking element  30  until locking element  30  has locked suture S to the suture anchor and expanded the body of the suture anchor. Furthermore, the force required to draw pull rod  35  through locking element so as to disengage pull rod  35  from locking element  30  is less than the force required to pull locking element  30  through the proximal end of body  25  of the knotless suture anchor  10  (due to the fact that distal end  115  of locking element  30  is sufficiently larger than proximal section  150  of bore  140 )—this ensures that pull rod  35  disengages from locking element  30  and locking element  30  is never pulled through the proximal end of body  25  of the knotless suture anchor  10 . In other words, the force required to pull locking element  30  through proximal end of body  25  is greater than the force required to draw pull rod  35  through locking element so as to disengage pull rod  35  from locking element  30  (i.e., the full activation force). 
         [0183]    In addition, the shape of proximal surface  191  of enlarged head  180  of pull rod  35  also influences the proximal force at which enlarged head  180  will enter into, and begin moving through, bore  140  in locking element  30 . In a preferred form of the invention, proximal surface  146  of enlarged head  180  comprises a fillet of approximately 0.005 inches (or a chamfer of approximately 45 degrees). 
         [0184]    Further proximal movement of pull rod  35  (i.e., by way of moving lever  230  even further towards handle  190 ) causes pull rod  35  to completely pull enlarged head  180  through bore  140  and out of the proximal end of locking element  30  ( FIG. 34 ). 
         [0185]    As noted above, locking element  30  comprises a weakened section  132  located at the proximal end of locking element  30 . As enlarged head  180  encounters weakened section  132 , the weakened section will separate from locking element  30 , allowing a proximal portion of locking element  30  to detach from the locking element and be removed from the anchor by pull rod  35  ( FIG. 34 ). At this point, inserter  15  can be removed from the hole H in bone B (see  FIGS. 35 and 36 ), leaving the knotless suture anchor  10  secured in the hole H in the bone B, and with the suture S secured to the knotless suture anchor and emanating from the bone hole H, whereby to secure the suture (and hence the tissue which the suture S has been passed through) to the bone B. 
       Additional Constructions 
       [0186]    In some cases the suture anchor may be subjected to transverse forces as it is advanced towards, and/or inserted into, the bone hole. This is particularly true where the suture anchor must be advanced through a tight corridor (e.g., such as in arthroscopic surgery), or along a tortuous path (e.g., such as when being advanced to a labral repair site within the hip), since in these situations the suture anchor may accidentally bump into intervening structures and/or the suture anchor may need to turn along a curved sheath during insertion. When this occurs, the suture anchor may be damaged and/or moved out of alignment with its inserter, etc., which can result in ineffective anchor placement in the bone. 
         [0187]    Accordingly, in another embodiment of the present invention, and looking now at  FIGS. 37-48 , means are provided to shield and mechanically support knotless suture anchor  10  as it is advanced towards, and/or inserted into, the bone hole. More particularly, in this form of the invention, inserter  15  comprises a retractable sheath  310  which is co-axial with, and external to, the aforementioned inserter shaft  195 . Inserter  15  also comprises an overtube  315 . In this form of the invention, shaft  195  is secured to handle  190  ( FIG. 42 ), retractable sheath  310  is coaxially mounted about shaft  195  and spring-biased in a distal direction by a compression spring  320 , and overtube  315  is coaxially mounted about retractable sheath  310  and secured to handle  190 . Preferably, when retractable sheath  310  is under the influence of compression spring  320 , the distal end surface  325  of retractable sheath  310  is disposed proximal to the distal end of knotless suture anchor  10 , but distal to the proximal end of knotless suture anchor  10  (see  FIGS. 38 and 40 ). More preferably, the distal end of retractable sheath  310  is located between the midpoint of knotless suture anchor  10  and the distal end of knotless suture anchor  10 . In this way, retractable sheath  310  can cover, and hence protect, the major length of knotless suture anchor  10  as the knotless suture anchor is advanced to the surgical site, but still expose the distal end of knotless suture anchor  10  so as to facilitate insertion of the knotless suture anchor into a bone hole. See  FIGS. 37-42 . However, when retractable sheath  310  is forced proximally, against the power of compression spring  320 , knotless suture anchor  10  is completely exposed. See  FIGS. 43-48 . Preferably retractable sheath  310  and overtube  315  have distal markings  326  and  327 , respectively, which provide indication of anchor depth. For example, when markings  326  and  327  align, the anchor is at the preferred depth. Additionally, retractable sheath  310  preferably has a slot  311  extending from its distal end (see  FIGS. 40 and 46 ) to allow suture to pass from within retractable sheath  310  (i.e., from knotless suture anchor  10  and/or shaft  195 ) to outside retractable sheath  310 . Slot  311  is preferably rotationally aligned with side opening  90  in knotless suture anchor  10  and opening  227  in the side wall of shaft  195 . 
         [0188]    In use, and looking now at  FIGS. 49-52 , retractable sheath  310  is initially disposed in its distal position, i.e., compression spring  320  actively pushes the proximal end of retractable sheath  310  away from handle  190 , so that retractable sheath  310  covers the majority of the length of knotless suture anchor  10 , but leaves the distal tip of the knotless suture anchor  10  exposed for easy locating into a bone hole H. Thereafter, when knotless suture anchor  10  is to be deployed into the bone hole H, the knotless suture anchor  10  is advanced (e.g., through an arthroscopic cannula) to the surgical site, with retractable sheath  310  covering, and protecting, the knotless suture anchor  10  during such advancement. Overtube  315  prevents retractable sheath  310  from prematurely retracting while the knotless suture anchor  10  is being delivered to the bone site. For example, the knotless suture anchor  10  may be passed through a cannula with an elastomeric septum; the septum, being grip-like in nature, will tend to grip the retractable sheath  310  and, consequently, retract the retractable sheath, thus removing some or all of the protection it was providing to the knotless suture anchor  10 . Overtube  315  provides protection against this occurrence as the septum will bear against the overtube  315  (it being the outermost surface) instead of retractable sheath  310 . Then the exposed distal tip of knotless suture anchor  10  is placed into bone hole H ( FIGS. 49 and 50 ), with the distal end of retractable sheath  310  contacting the outer surface of the bone B. In this position, retractable sheath  310  contacts the outer surface of the bone B about the perimeter of the bone hole H and provides additional mechanical support against any transverse forces that may be applied to the knotless suture anchor  10  from the inserter  15 , for example, if there is a misalignment between the arthroscopic portal and the axis of the bone hole H. The knotless suture anchor  10  is then advanced into the bone hole H. This is done by moving inserter  15  distally. As inserter  15  moves distally, shaft  195  advances the knotless suture anchor  10  into the bone hole H while the engagement of retractable sheath  310  with the outer surface of the bone B causes the retractable sheath  310  to remain stationary relative to the bone B. See  FIGS. 51 and 52 . Under this action, the power of compression spring  320  is overcome and the advancing handle  190  moves shaft  195  distally within retractable sheath  310 . In other words, pushing handle  190  distally moves shaft  195  distally, while compression spring  320  allows retractable sheath  310  to remain seated on the outer surface of the bone B and retract into the advancing handle  190 . During advancement of knotless suture anchor  10  into the bone hole H, retractable sheath  310  continues to provide mechanical support to the knotless suture anchor  10  as the knotless suture anchor  10  is pressed further into the bone hole. In this manner, retractable sheath  310  protects and supports knotless suture anchor  10  during delivery into the bone hole H. 
         [0189]    In a preferred embodiment, retractable sheath  310  and overtube  315  are formed out of biocompatible materials such as stainless steel. In an alternative embodiment, retractable sheath  310  is formed out of a transparent polymer. In this embodiment, a distal marking  328  ( FIG. 44 ) on the shaft  195  can be visualized through the transparent retractable sheath  310  to provide visual indication of anchor depth. 
         [0190]    In another embodiment, the spring  320  may be sufficiently strong so as to overcome inadvertent retraction of retractable sheath  310  during delivery; hence, in this form of the invention, overtube  315  may be omitted. 
       Forming Shaft  195  With a Flexible Construction 
       [0191]    In some situations it can be advantageous to form shaft  195  with a flexible construction. By way of example but not limitation, inserter  15  may sometimes approach the bone hole at an angle to the longitudinal axis of the bone hole. Where this occurs, and where shaft  195  is rigid, the rigid nature of shaft  195  can cause knotless suture anchor  10  to resist tracking the orientation of the bone hole during insertion of the knotless suture anchor into the bone hole. This can put additional stress on knotless suture anchor  10 , and/or on the connection between knotless suture anchor  10  and shaft  195 , and/or on other components of knotless suture anchor system  5  (e.g., it can put additional stress on pull rod  35 ). 
         [0192]    To this end, and looking now at  FIGS. 53-56 , shaft  195  may be formed so as to be flexible, so that if inserter  15  approaches bone hole H at an angle to the longitudinal axis of the bone hole ( FIG. 53 ), shaft  195  can flex so as to allow knotless suture anchor  10  to track the orientation of the bone hole during insertion of the knotless suture anchor into the bone hole ( FIGS. 54 and 55 ). Various approaches may be used to form shaft  195  so that it is flexible, e.g., shaft  195  may be formed out of a flexible material (e.g., a superelastic material such as Nitinol) and/or shaft  195  may be provided with a series of laser cuts  400  ( FIG. 55 ) so as to render the shaft flexible. 
         [0193]    It will be appreciated that, in this form of the invention, pull rod  35  is also formed so as to be flexible. 
       Inserter Having Shaft  195  Carried By a Slidable Inner Carriage 
       [0194]    As noted above, in some cases the knotless suture anchor (e.g., knotless suture anchor  10 ) may be subjected to transverse forces as the knotless suture anchor is advanced towards, and/or inserted into, bone hole H. This is particularly true where knotless suture anchor  10  must be advanced through a tight corridor (e.g., such as during arthroscopic surgery), and/or along a tortuous path (e.g., such as when the knotless suture anchor is being advanced to a labral repair site within the hip joint), since in these situations (as well as in others) knotless suture anchor  10  may accidentally bump into intervening structures, and/or knotless suture anchor  10  may need to pass through a curved sheath during advancement to the insertion site. When this occurs, knotless suture anchor  10  may be damaged, and/or moved out of alignment with its inserter, etc., either of which can result in ineffective anchor placement in the bone. This is particularly true where the size of knotless suture anchor  10  and its associated inserter are quite small (e.g., where knotless suture anchor  10  is approximately 2.8 mm in diameter). 
         [0195]    Accordingly, with the construction shown in  FIGS. 37-48 , inserter  15  includes the aforementioned retractable sheath  310  which is coaxial with, and external to, the inserter shaft  195 . This retractable sheath  310  is coaxially mounted about shaft  195  and is spring-biased in a distal direction by the compression spring  320 . As a result of this construction, retractable sheath  310  covers at least a portion of knotless suture anchor  10  as the knotless suture anchor is advanced to the insertion site, however, when handle  190  is thereafter used to push the knotless suture anchor into the bone, engagement of retractable sheath  310  with the outer surface of the bone causes the retractable sheath  310  to retract into handle  190 . In this way, retractable sheath  310  protects and supports the knotless suture anchor  10  during delivery to the bone hole, but does not interfere with insertion of the knotless suture anchor  10  into the bone hole. 
         [0196]    In addition, with the construction shown in  FIGS. 37-48 , it has been found desirable to provide the aforementioned overtube  315 , where overtube  315  is coaxially mounted about retractable sheath  310  and inserter shaft  195 . Overtube  315  prevents retractable sheath  310  from prematurely retracting while the knotless suture anchor  10  is being delivered to the insertion site. By way of example but not limitation, the knotless suture anchor  10  may be passed through a cannula having an elastomeric septum; if the retractable sheath  310  were not protected by overtube  315 , the septum, being grip-like in nature, could tend to grip retractable sheath  310  and, consequently, prematurely retract the retractable sheath  310 , thus removing some or all of the protection the retractable sheath  310  provides to the knotless suture anchor  10  during advancement to the insertion site. Overtube  315  provides protection against this occurrence as the septum will bear against overtube  315  (since it provides the outermost surface of the assembly) instead of bearing against retractable sheath  310 . 
         [0197]    It will be appreciated that the construction shown in  FIGS. 37-48  essentially provides an inserter comprising the handle  190 , the inserter shaft  195  fixed to handle  190 , the spring-biased retractable sheath  310  slidably mounted to handle  190 , and the overtube  315  fixedly mounted to handle  190 . 
         [0198]      FIGS. 57-71  show an alternative construction for supporting and protecting knotless suture anchor  10  during approach and insertion into bone. More particularly, with the construction shown in  FIGS. 57-71 , there is provided an inserter handle  405  having an overtube  315  fixedly mounted thereto and extending distally therefrom. Overtube  315  is preferably curved (as shown in FIGS.  57  and  62 - 71 ) so as to enable curved (angled) delivery of knotless suture anchor  10 . This can be beneficial when the desired angle of the bone hole differs from the access angle through the intervening tissue to the bone site. For example, in repairing the hip labrum, it is desirable to create a bone hole (and subsequently deliver an anchor) at an angle which tilts away from the acetabular cup. This angulation of the bone hole reduces the chance that the bone hole (and the subsequent anchor delivery) will penetrate into the acetabular cup surface. 
         [0199]    Overtube  315  preferably comprises at least one tooth  410  at its distal end for engaging bone. Whereas the retractable sheath  310  discussed above supports anchor delivery to the bone hole, retractable sheath  310  does not engage the bone in such a way as to withstand transverse loads that may be imparted to knotless suture anchor  10  and/or to inserter shaft  195  during delivery of the knotless suture anchor into the bone hole, i.e., retractable sheath  310  is spring biased and, as such, cannot be, for example, pressed into the bone to securely engage the bone. Because the retractable sheath  310  cannot withstand transverse forces, knotless suture anchor  310  and/or inserter shaft  195  can be subjected to transverse forces during anchor insertion when the angle of the bone hole differs from the access angle through the intervening tissue to the site of the bone hole; this may result in ineffective anchor delivery and/or damage to the anchor and/or inserter shaft. The overtube  315 , with at least one tooth  410  at its distal end for securely engaging bone, can withstand transverse forces that may be imparted during anchor delivery. This may occur when the angle of the bone hole differs from the access angle through the intervening tissue to the site of the bone hole (as previously discussed). This may also occur when overtube  315  is curved; in this construction (and as shown in  FIGS. 62-75 ), an impact force applied to driver head  425  of inserter  15  for delivery of anchor  10  into the bone hole causes flexible inserter shaft  195  to contact the inside surface of overtube  315  and impart distal- and transverse-directed forces to overtube  315 . As a result, the overtube  315  may impart distal- and transverse-forces against the bone surface; the at least one tooth  410  at the distal end of overtube  315  acts to securely engage overtube  315 , and hence inserter  15 , with the bone such that the forces imparted by overtube  315  against the bone surface will not cause the distal end of overtube  315  to shift on the bone surface, which could lead to ineffective placement of knotless suture anchor  10  and/or damage to knotless suture anchor  10  and/or inserter shaft  195 . In addition, with the construction in  FIGS. 62-75 , since the axis of impact differs from the bone hole location, transverse forces can act on overtube  315  as it contacts the bone. Overtube  315  also comprises a distal slot  415  ( FIG. 58 ) so as to enable passage of suture S from knotless suture anchor  10  through overtube  315 . Distal slot  415  extends to the distal end of overtube  315  so as to enable suture S to freely slide out of overtube  315  when the knotless suture anchor  10  is disengaged from inserter shaft  195 . 
         [0200]    Inserter shaft  195  is slidably disposed within overtube  315 . Inserter shaft  195  is preferably flexible at its distal end (i.e., along the length extending along the curve of overtube  315 ). This can be accomplished by forming inserter shaft  195  out of a flexible material (e.g., a superelastic metal such as Nitinol) or by forming a series of laser cuts  400  in inserter shaft  195  (as can be seen in  FIG. 69 ) so as to render inserter shaft  195  flexible. The distal end of inserter shaft  195  releasably carries knotless suture anchor  10  in the manner previously described. 
         [0201]    The proximal end of inserter shaft  195  is fixedly attached to a slidable inner carriage  420  ( FIGS. 66 ,  68  and  70 ) which is movably mounted within inserter handle  405 . Slidable inner carriage  420  is moved relative to inserter handle  405  by applying force to a driver head  425  which is exposed at the proximal end of inserter handle  405 . Thus, by moving driver head  425  distally (e.g., by striking driver head  425  with a mallet), slidable inner carriage  420  is moved distally, whereby to move inserter shaft  195  (and hence knotless suture anchor  10 ) distally. 
         [0202]    In one preferred form of the invention, a removable stop  427  is releasably secured to driver head  425 . Removable stop  427  prevents driver head  425  from being inadvertently driven distally, and hence prevents slidable inner carriage  420 , inserter shaft  195  and knotless suture anchor  10  from being inadvertently driven distally. However, when removable stop  427  is removed from driver head  425 , the driver head (and hence slidable driver carriage  420 , inserter shaft  195  and suture anchor  10 ) may be moved distally. 
         [0203]    And in one preferred form of the invention, slidable inner carriage  420  comprises one or more projections  428 , and inserter handle  405  comprises one or more resilient fingers  429 , whereby to permit slidable inner carriage  420  to move distally within inserter handle  405  but prevent slidable inner carriage  420  from moving proximally within inserter handle  405 . More particularly, in this form of the invention, projections  428  and resilient fingers  429  form a ratchet-type mechanism for ensuring substantially one-way movement of slidable inner carriage  420  relative to inserter handle  405 . As a result, when driver head  425  is moved distally (and hence slidable inner carriage  420  is moved distally), projections  428  and resilient fingers  429  cooperate to prevent slidable inner carriage  420  from thereafter returning substantially proximally. As the one or more projections  428  encounter the one or more fingers  429 , there is resistance against slidable inner carriage  420  moving distally within inserter handle  405 . In other words, when one or more resilient fingers  429  encounter one or more projections  428 , a threshold force is required to flex resilient finger(s)  429  sufficiently for projection(s)  428  to pass under resilient finger(s)  429  and thus allow slidable inner carriage  420  to move distally within inserter handle  405 . In one embodiment, when slidable inner carriage  420  is in its proximal position ( FIG. 66 ), a resilient finger  429  is adjacent to a projection  428  so as to create a force which must be overcome before slidable inner carriage  420  advances distally. This feature can be advantageous, for example, so that as the inserter  15  is advanced to the bone site, any inadvertent distal pressure or force on the driver head  425  and/or actuation lever  430  will not advance the slidable inner carriage  420  (and hence advance knotless suture anchor  10  further out of the overtube  315 ). 
         [0204]    Slidable inner carriage  420  includes an actuation lever  430  which is pivotally connected to slidable inner carriage  420 . Actuation lever  430  is connected to the proximal end of pull rod  35  for actuating knotless suture anchor  10  once the knotless suture anchor is inside bone hole H, whereby to bind suture S to knotless suture anchor  10  and secure the knotless suture anchor to the bone. It will be appreciated that pull rod  35  extends through inserter shaft  195  for connection to actuation lever  430 . 
         [0205]    The construction shown in  FIGS. 57-71  may be used in the following manner. First, a bone hole (e.g., a bone hole H) is created in the bone. Bone hole H is preferably created by passing a drill bit or punch through a curved guide and into the bone. The drill bit or punch and the curved guide are then removed from the surgical site. Next suture S is passed through the tissue that is to be secured to the bone. Then suture S is threaded through knotless suture anchor  10 . More particularly, the inserter and knotless suture anchor are initially in the position shown in  FIGS. 57-59 , i.e., with slidable inner carriage  420  positioned within inserter handle  405  so that knotless suture anchor  10  is substantially shielded, yet slightly exposed, at the distal end of overtube  315 , and so that driver head  425  is spaced from the proximal end of inserter handle  405 . Removable stop  427  is removed from driver head  425  ( FIGS. 60 and 61 ) and suture S is threaded through knotless suture anchor  10  using suture threader  20  in the manner previously described ( FIGS. 62-67 ). Then inserter handle  405  is used to advance knotless suture anchor  10  (still substantially shielded within overtube  315 ) to the insertion site (i.e., bone hole H). Distal end of anchor  10  may be used to help locate bone hole H. Inserter  15  is then rotated to the desired direction of curved delivery; for example, for hip labral repair, the curvature of inserter  15  would typically be directed away from the acetabular cup. The exposed distal end of the anchor  10  is placed into bone hole H by manual manipulation of inserter handle  405 . Anchor  10  is inserted into bone hole H until the distal end of overtube  315  contacts bone. Tooth  410  on the distal end of overtube  315  is then engaged with bone. See  FIG. 72 . With overtube  315  sufficiently engaged with bone, driver head  425  is moved distally (e.g., by striking the driver head  425  with a mallet), whereby to move slidable inner carriage  420  distally, whereby to move flexible inserter shaft  195  distally, whereby to advance knotless suture anchor  10  out of overtube  315  and into bone hole H ( FIGS. 68 ,  69  and  73 ). Suture S is then tensioned to adjust the position and/or tension of the tissue relative to knotless suture anchor  10  (and hence the bone). Then actuation lever  430  is activated, whereby to bind suture S to knotless suture anchor  10  and secure the tissue to the bone ( FIGS. 70 ,  71  and  74 ). Then the inserter is withdrawn from the insertion site by withdrawing inserter handle  405  proximally, leaving knotless suture anchor  10  deployed in bone hole H. See  FIG. 75 . 
         [0206]    Thus it will be seen that with the construction shown in  FIGS. 57-71 , overtube  315  is fixed to inserter handle  405 , and the driver head  425  is used to move slidable inner carriage  420  distally, whereby to advance flexible inserter shaft  195  distally out of overtube  315 , whereby to insert knotless suture anchor  10  into bone hole H. Thus, overtube  315  protects and supports knotless suture anchor  10  during advancement to the insertion site and, by engaging the bone surface, resists transverse forces that otherwise would be subjected onto the knotless suture anchor  10  and/or inserter shaft  195 . 
         [0207]    In an alternative embodiment, overtube  315  is formed in a straight configuration. In this embodiment, inserter shaft  195  may be flexible or may be substantially rigid (i.e., it can omit features such as laser cuts  400  that provide flexibility to inserter shaft  195 ). 
         [0208]    In yet another alternative embodiment, knotless suture anchor  10  does not require actuation to lock suture S to the knotless suture anchor. For example, suture S may be locked by being squeezed or pressed between the body  25  of knotless suture anchor  10  and the side of bone hole H. Thus, the act of pressing knotless suture anchor  10  into bone hole H locks suture S to body  25  of knotless suture anchor  10 . In this form of the invention, there is no need for actuation lever  430  or pull rod  35 . 
       Use of the Novel Knotless Suture Anchor System for Other Tissue Re-Attachment 
       [0209]    It should be appreciated that knotless suture anchor system  5  may also be used for re-attaching other soft tissue of the hip joint, or for re-attaching tissue of other joints, or for re-attaching tissue elsewhere in the body. In this respect it should be appreciated that knotless suture anchor system  5  may be used to attach soft tissue to bone or soft tissue to other soft tissue, or for attaching objects (e.g., prostheses) to bone or other tissue. 
       Modifications of the Preferred Embodiments 
       [0210]    It should be understood that many additional changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the present invention, may be made by those skilled in the art while still remaining within the principles and scope of the invention.