Abstract:
Bone anchor implantation devices and methods for their use are disclosed. The bone anchor implantation devices and methods find particular application in maintaining or improving urinary continence by suspending or stabilizing the bladder neck. The devices and methods simplify procedures for suspending or stabilizing the bladder neck and further reduce their invasiveness.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. Pat. application Ser. No. 08/744,439 filed on Nov. 8, 1996. U.S. Pat. No. 6,053,936. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a bone anchor implantation device for use in maintaining or improving urinary continence. 
     BACKGROUND OF THE INVENTION 
     Urinary incontinence is a widespread problem in the United States and throughout the world. Urinary incontinence affects people of all ages and can severely impact a patient both physiologically and psychologically. 
     In approximately 30% of the women suffering from urinary incontinence, incontinence is caused by intrinsic sphincter deficiency (ISD), a condition in which the valves of the urethral sphincter do not properly coapt In approximately another 30% of incontinent women, incontinence is caused by hypermobility, a condition in which the muscles around the bladder relax, causing the bladder neck and proximal urethra to rotate and descend in response to increases in intraabdominal pressure. Hypermobility may be the result of pregnancy or other conditions which weaken the muscles. In an additional group of women with urinary incontinence, the condition is caused by a combination of ISD and hypermobility. 
     In males, urinary incontinence may be the consequence of post radical prostatectomy, which can destroy the valves of the urethral sphincter. 
     In addition to the conditions described above, urinary incontinence has a number of other causes, including birth defects, disease, injury, aging, and urinary tract infections. 
     Numerous approaches for treating urinary incontinence are available. For example, several procedures for stabilizing and/or slightly compressing the urethra so as to prevent the leakage of urine have been developed. The stabilizing or compressive force may be applied directly by sutures passing through the soft tissue surrounding the urethra or, alternatively, may be applied by means of a sling suspended by sutures. In many procedures bone anchors are inserted into the pubic bone or symphysis pubis in order to anchor the sutures to the bone. The present invention simplifies such procedures and firther reduces their invasiveness. 
     SUMMARY OF THE INVENTION 
     The present invention relates to devices and methods for inserting anchors, such as bone anchors, into a bone or tissue. 
     One aspect of the present invention is a bone anchor implantation device comprising an elongated member having a first end and a second end. A bone anchor is releasably engaged to the elongated member in the vicinity of the first end. A protective sheath is mounted over the bone anchor. The protective sheath is axially movable relative to the bone anchor such that the bone anchor is exposed from the sheath as the bone anchor is pressed into a bone by the elongated member. 
     In one embodiment of the present invention, the device for inserting a bone anchor into bone comprises a first handle and a second handle. The first handle has a releasably-attached bone anchor at a first end of the first handle. The bone anchor extends from the first handle. The second handle is adjacent to the first handle. The second handle has a cannula extending therefrom at a first end of said second handle such that the bone anchor is located within the cannula. The first and second handles are movable with respect to each other to effect extension of the bone anchor out of the cannula. 
     In one aspect of this embodiment, the first handle has an inserter shaft attached to the first end of the first handle. The inserter shaft has a proximal end and a distal end and is adapted to releasably engage a bone anchor. The second handle has a proximal end and a distal end and is hingedly attached to the first handle. The cannula has a proximal end, a distal end, and a central bone extending therethrough. The cannula is aligned with the inserter shaft such that the inserter shaft is inside the central bone of the cannula and is extendable and retractable therefrom. 
     In another aspect of this embodiment, the device further comprises a biasing member disposed between the first handle and the second handle. The biasing member applies a force biasing the first handle and the second handle apart. The biasing member may comprise a spring disposed between the first handle and the second handle. 
     In yet another aspect of this embodiment, the device is adapted for transvaginal insertion of a bone anchor. 
     The device may further comprise a locking mechanism for locking the device in a position in which the inserter shaft is fully retracted in the cannula. 
     In one version of the device, the locking mechanism also locks the device in a position in which the inserter shaft is fully extended from the cannula. 
     Preferably, the inserter shaft has a pair of longitudinal grooves therein for receiving a suture. 
     In a further preferred embodiment, the cannula has a pair of longitudinal slots therein for receiving a suture. Preferably, the grooves in the inserter shaft and the slots in the cannula are aligned and coextensive. 
     In a preferred version of the device the inserter shaft and the cannula are curved. 
     Alternatively, the inserter shaft and the cannula are straight. 
     Preferably, the inserter shaft is at an angle of approximately 90° relative to the first handle and the cannula is at an angle of approximately 90° relative to the second handle. 
     In one version of the device, a hinge is disposed between the proximal end of the first handle and the proximal end of the second handle. 
     Preferably, the distal end of the cannula has a sharp point adapted for piercing tissue. 
     In yet another aspect of the device, a protective cap is located at the distal end of the cannula. 
     Another aspect of the invention is a method for inserting a bone anchor into a bone. One stop of the method comprise positioning an inserter device against tissue overlying the bone. The inserter device has a first handle having a releasably-attached bone anchor extending therefrom at a first end of the first handle. A second handle is located adjacent to the first handle. The second handle has a cannula extending therefrom at a first end of the second handle and the bone anchor is located within the cannula. Another step of the method comprises inserting the cannula through tissue overlying the bone. A further step of the method comprises moving the first handle and the second handle with respect to each other to force the bone anchor out of the cannula and into the bone. 
     In one aspect of the method, the bone anchor is implanted transvaginally into the pubic bone. Preferably, the bone anchor is implanted in posterior pubic bone. In a further preferred embodiment of the method the bone anchor is implanted lateral to the symphysis pubis and cephalad to the inferior edge of the pubic bone. 
     Preferably, at least one bone anchor is implanted on either side of the urethra. 
     The method may further comprise compressing or stabilizing the bladder neck with a suture attached to the bone anchor. In addition, the method may further comprise the steps of creating an opening in the tissue between the vaginal wall and the urethra, positioning a sling in the opening, and compressing or stabilizing the bladder neck with the sling using sutures connected between the sling and the bone anchors. 
     In one version of the method, two bone anchors are implanted on each side of the urethra. In this version, one bone anchor on each side of the urethra may be located lateral to the symphysis pubis and cephalad to the inferior edge of the pubic bone. The second bone anchor may be located on the cephalad aspect of the ramus. 
     Yet another aspect of the present invention is a device for inserting a bone anchor into a bone comprising a handle, a shaft, and a bone anchor mount for releasably engaging a bone anchor. The handle has a proximal end and a distal end. The shaft has a first end and a second end. The first end of the shaft is connected to the distal end of said handle. The bone anchor mount is connected to the second end of the shaft and oriented toward the handle so that the bone anchor may be inserted by applying a retrograde force to the bone anchor. 
     The device may further comprise a protective sheath connected to said bone anchor mount for isolating said bone anchor from contact with tissue prior to implantation of said bone anchor into a bone. 
     Preferably, the shaft is hook shaped. 
     In one aspect of the device, the bone anchor mount comprises an outer cylinder, an inner cylinder, and a tapered bone anchor receptacle for releasably engaging a bone anchor. The inner cylinder is rigidly connected to the outer cylinder and extends proximally therefrom. The bone anchor receptacle is rigidly connected to said inner cylinder and extends proximally therefrom. 
     In one aspect of the device, the outer cylinder has a cavity therein. 
     In a further aspect of the device, the outer cylinder has a distal end and a proximal end. An annular shoulder is located at the proximal end of the outer cylinder. The inner cylinder is connected to the outer cylinder within the cavity of the outer cylinder. 
     In one version of the device, the protective sheath comprises a first telescoping cylinder, a second telescoping cylinder, and a spring. The first telescoping cylinder has a proximal end, a distal end and a lumen extending therethrough. A first shoulder is located at the distal end of the first telescoping cylinder and a second shoulder is located at the proximal end of the first telescoping cylinder. The second telescoping cylinder has a proximal end, a distal end and a lumen extending therethrough. A first shoulder is located at the distal end of the second telescoping cylinder and a second shoulder is located at the proximal end of the second telescoping cylinder. The first shoulder of the first telescoping cylinder engages the shoulder of the outer cylinder. The second shoulder of the first telescoping cylinder engages the first shoulder of the second telescoping cylinder. The spring is disposed between the second shoulder of the second telescoping cylinder and the outer cylinder, whereby the first and second telescoping cylinders are movable between a first position in which they are extended from the outer cylinder thereby covering the bone anchor, and a second position in which they are retracted in the cavity of the outer cylinder, thereby exposing the bone anchor. 
     Another aspect of the present invention is a method for inserting a bone anchor releasably engaged to a bone anchor implantation device into a bone comprising the steps of locating a bone anchor implantation site on the bone and applying a retrograde force to the bone anchor to implant the bone anchor into the bone. 
     Yet another aspect of the present invention is a method for inserting a bone anchor releasably engaged to a bone anchor implantation device into a bone comprising the steps of locating a bone anchor implantation site on the bone and pulling the bone anchor implantation device to implant the bone anchor into the bone. Preferably, the pulling step comprises applying a retrograde force to the bone anchor implantation device. Preferably, the locating and implanting steps are accomplished transvaginally. 
     Preferably, the pulling step utilizes a bone anchor implantation device comprising a handle, a shaft, and a bone anchor mount for releasably engaging a bone anchor. The handle has a proximal end and a distal end. The shaft has a first end and a second end. The first end of the shaft is connected to the distal end of said handle. The bone anchor mount is connected to the second end of the shaft and oriented toward the handle so that the bone anchor may be inserted by applying a retrograde force to the bone anchor. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of the bone anchor implantation device. 
     FIG. 2 is an exploded view of the anchor implantation device. 
     FIG. 3 is a cross-sectional view of the distal end of the cannula showing the protective cap therein taken along line  3 — 3  of FIG.  2 . 
     FIG. 4 is a cross-sectional view of the bone anchor implantation device of FIG. 1 taken along line  4 — 4  of FIG.  1 . 
     FIG. 5 is a cross-sectional view of the bone anchor implantation in its locked configuration. 
     FIG. 6 is a plan view of an alternate embodiment of the bone anchor implantation device having a keyhole-shaped bore in the second handle. 
     FIG. 7 is a cross-sectional view taken along line  7 — 7  of the alternate embodiment shown in FIG. 6 locked in the position in which the inserter shaft is fully extended from the cannula. 
     FIG. 8 is a cross-sectional view of the alternate embodiment of FIG. 6 locked in the position in which the inserter shaft is fully reacted within the cannula. 
     FIG. 9 is a cross-sectional view of the distal end of the inserter shaft in the cannula showing location of the bone anchor implantation site by sliding the cannula along the endopelvic fascia 
     FIG. 10 is a cross-sectional view of the distal end of the inserter shaft and the cannula showing the inserter shaft penetrating the protective cap near the distal end of the cannula. 
     FIG. 11 is a cross-sectional view of the distal ends of the inserter shaft in the cannula showing the bone anchor being driven into the bone. 
     FIG. 12 shows the bone anchor with sutures extending therefrom after implantation into the bone. 
     FIG. 13 is a side view of a bone anchor implantation device having a hooked shaft. 
     FIG. 14 is an enlarged side view of a distal portion of the bone anchor implantation device taken along line  14 — 14  of FIG. 13 showing the internal structure of the bone anchor mount. 
     FIG. 15 is a perspective view of the bone anchor mount. 
     FIG. 16 is a cross sectional view of the bone anchor mount of FIG. 15 taken along line  16 — 16 . 
     FIG. 17 is a schematic view showing the interior structure of the handle an alternate embodiment of the bone anchor implantation device inserted into the vagina with the proximal end of the second telescoping cylinder contacting the pubic bone. 
     FIG. 18 is an enlarged view of the shaft of the alternate embodiment of the bone anchor implantation device illustrated in FIG.  17 . 
     FIG. 19 is a cross sectional view of the shaft of the bone anchor implantation device shown in FIG. 18 taken along line  19 — 19  of FIG.  18 . 
     FIG. 20 is a schematic view showing the interior structure of the handle of an alternate embodiment of the bone anchor implantation device illustrated in FIG. 17 inserted into the vagina showing the implantation of a bone anchor into the pubic bone and the compression of the spring. 
     FIG. 21 is a side view of the bone anchor implantation device of FIG. 13 showing a protective sheath contacting the pubic bone. 
     FIG. 22 is a side view of the bone anchor implantation device of FIG. 13 showing the bone anchor implanted into the pubic bone. 
     FIG. 23 is a cross sectional view of the bone anchor mount and protective sheath when the protective sheath is contacting the pubic bone. 
     FIG. 24 is a cross sectional view of the bone anchor mount and the protective sheath when the bone anchor is being implanted into the pubic bone. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention relates to a device for affixing a suture-carrying anchor to bone. It also relates to methods for improving or maintaining a patient&#39;s urinary continence in which bone anchors are inserted transvaginally into the posterior portion of the pubic bone or symphysis pubis and devices for use in such methods. As used herein, the terms “transvaginally” or “transvaginal access” refer to access through the vaginal introitus or from within the vagina, as opposed to access from the patient&#39;s abdominal side. 
     As will be described in more detail below, the methods and devices of the present invention drive a bone anchor with at least one suture attached thereto through the vaginal wall and into the posterior portion of the pubic bone or symphysis pubis. Preferably, at least one bone anchor is driven into the pubic bone on either side of the urethra. However, one of skill in the art will appreciate that a single bone anchor may also be used. The sutures attached to the bone anchors extend through the vaginal wall and may then be attached to the endopelvic fascia, the vaginal wall, a sling, or other material to stabilize and/or slightly compress the urethra, thereby improving or maintaining the patient&#39;s urinary continence. 
     TWO HANDLE BONE ANCHOR IMPLANTATION DEVICE 
     In one embodiment, the anchor implantation device has a first handle having an inserter shaft attached thereto. The inserter shaft is adapted to releasably engage or attach to a bone anchor. A second handle is hingedly attached to the first handle and has a cannula attached thereto. The cannula has a central bore extending therethrough. The cannula is aligned with the inserter shaft such that the inserter shaft is inside the central bore of the cannula and is extendable from and retractable in the cannula. Preferably, a biasing member is disposed between the first handle and the second and biases the first handle and the second handle apart. 
     FIGS. 1 and 2 provide a plan view and an exploded view of an anchor implantation device  10  for introducing a bone anchor  22  transvaginally and driving it into the pubic bone or symphysis pubis. The device comprises a first handle  12  having a proximal end  14 , a central region  16 , and a distal end  18 . The first handle  12  may be made of any relatively firm material, including plastic or metal. Preferably, the first handle  12  is made of plastic, aluminum, stainless steel, or titanium. However, those skilled in the art will appreciate that a wide range of other materials may also be employed. 
     The first handle  12  may be configured in any of a variety of shapes compatible with vaginal insertion. Preferably, the first handle  12  is rectangular. However, those skilled in the art will appreciate that a variety of configurations may be employed, such as a handle which tapers towards the distal end, and the present invention contemplates the use of any handle configuration compatible with vaginal insertion. 
     The dimensions of the first handle  12  are also compatible with vaginal insertion. The first handle  12  may be from about 4 inches to about 8 inches in length, about 0.25 inches to about 1.25 inches in width, and about 0.05 inches to about 0.5 inches in height. Preferably, the first handle  12  is about 5 inches to about 7 inches in length, about 0.5 inches to about 1 inch in width, and about 0.1 inches to about 0.3 inches in height. More preferably, the first handle  12  is has a length of 6 inches, a width of 0.75 inches and a height of 0.2 inches 
     An inserter shaft  20  adapted for releasably engaging a bone anchor  22  is located near the distal end  18  of the first handle  12 . A variety of bone anchors can be used. Preferably, an anchor such as that described in published PCT application WO 95/16399, entitled “Method and Apparatus for Securing Soft Tissues, Tendons, and Ligaments to Bone,” filed Jun. 22, 1993, the disclosure of which is incorporated herein by reference, is used. 
     The inserter shaft has a distal end  24 , a central region  26 , and a proximal end  28 . Preferably, the inserter shaft extends at an angle of about 90° from the first handle  12 . 
     The inserter shaft  20  may be made of any of a variety of materials, including steel, stainless steel, aluminum, titanium, and plastic, but is preferably made of stainless steel. Additionally, the inserter shaft  20  may have a variety of cross sectional shapes including rectangular, hexagonal, or triangular but preferably the inserter shaft  20  has a circular cross section. 
     The inserter shaft  20  may be located from about 0.05 inches to about 0.5 inches from the distal end  18  of the first handle  12 . Preferably, the inserter shaft  20  is located from about 0.1 inches to about 0.3 inches from the distal end  18 . More preferably, the inserter shaft  20  is located 0.2 inches from the distal end  18  of the handle. 
     The length of the inserter shaft  20  is consistent with transvaginal delivery of the releasable bone anchor  22 . Thus, the inserter shaft  20  may be from about 0.5 inches to about 1.5 inches long. Preferably, the inserter shaft  20  is from about 0.75 inches to about 1.25 inches in length. More preferably, the inserter shaft  20  is 1 inch in length. 
     Preferably, the proximal end  28  and the central region  26  of the inserter shaft  20  have an equal cross sectional area, which is larger than the cross sectional area of the bone anchor  22  and distal end  24 . Thus, a shoulder  17  is formed at the junction between the central region  26  of the inserter shaft and the distal region of the inserter shaft. The shoulder  17  acts as a stop which will not penetrate the cortical shell of the bone. 
     The diameter of the inserter shaft is dependent upon the size of the bone anchor. In embodiments in which the inserter shaft  20  is cylindrical, the diameter of the proximal end  28  and central region  26  of the inserter shaft is from about 0.1 inches to about 0.3 inches, and that of the distal end  24  is from about 0.04 inches to about 0.2 inches. Preferably, the diameter of the proximal end  28  and central region  26  of the inserter shaft is from about 0.15 inches to about 0.25 inches, and that of the distal end  24  is from about 0.07 inches to about 0.11 inches. More preferably, the diameter of the proximal end  28  and central region  26  of the inserter shaft is 0.2 inches and that of the distal end  24  is 0.09 inches. 
     Preferably, the inserter shaft  20  is curved as shown in FIGS. 1 and 2. As will be appreciated by those of skill in the art, the inserter shaft  20  may also be straight. In those embodiments in which the inserter shaft  20  is curved, the radius of curvature of the inserter shaft  20  is the distance between the pivot point of the hinge and the center of the inserter shaft. The radius of curvature of the inserter shaft  20  may be from about 3.5 inches to about 7.9 inches. Preferably, the radius of curvature of the inserter shaft  20  is from about 4.7 inches to about 6.9 inches. More preferably, the radius of curvature of the inserter shaft  20  is 5.8 inches. 
     The distal end  24  of the inserter shaft  20  is adapted to releasably engage a bone anchor  22 . In one embodiment, the bone anchor  22  is housed within a notch  30  at the distal end  24  of the inserter shaft, and frictionally engages the inner wall of the distal end  24  of the inserter shaft. However, it will be appreciated by those of skill in the art that the inserter shaft  20  may releasably engage the bone anchor  22  through a variety of means other than that described above, and such means are specifically contemplated by the present invention. 
     The distal end  24  of the inserter shaft may be hollow or solid and has a complementary shape to the proximal end of the bone anchor  22  to permit the bone anchor  22  to frictionally engage the distal end  24  of the inserter shaft. For example, the distal end  24  of the inserter shaft and the proximal end of the bone anchor may be square, rectangular, pentagonal, triangular or hexagonal in cross section. Preferably, the distal end  24  of the inserter shaft and the proximal end of the bone anchor are cylindrical. However, those skilled in the art will appreciate that numerous shapes may be employed, and the present invention specifically contemplates any such shape. 
     The central region  26  of the inserter shaft has a pair of grooves  32  therein for receiving a suture  54  attached to the bone anchor as illustrated in FIGS. 1 and 2. Preferably, the grooves  32  in the inserter shaft are coextensive with slots  34  in the outer cannula and are aligned with the slots  34 . 
     The device also comprises a second handle  36  hingedly connected to the first handle  12  and having a proximal end  38 , a central region  40 , and a distal end  42 . The second handle  36  may be fabricated from any of the materials discussed above with regard to the first handle  12 . Additionally, the second handle  36  may have any of the dimensions and shapes discussed above with regard to the first handle  12 . The preferred materials, dimensions, and shapes for the second handle  36  are the same as those discussed above with regard to the first handle  12 . 
     The second handle  36  has a cannula  44  positioned near its distal end  42  aid fixed within a bore  11  in the second handle by screws  13 . The cannula  44  has a proximal end  46 , a central region  48 , and a distal end  50 , with a central bore  52  running through its entire length. Preferably, the cannula  44  extends at an angle of about 90° from the second handle  36 . 
     The cannula  44  may be fabricated from any of the materials described above with regard to the inserter shaft  20 . Preferably, the. cannula  44  is made of stainless steel. 
     The cannula  44  may have any of the shapes discussed above with regard to the inserter shaft  20 . Preferably, the shape of the cannula  44  is the same as that of the inserter shaft  20 . 
     The cannula  44  is located approximately the same distance from the distal end  42  of the second handle as the inserter shaft  20  is from the distal end  18  of the first handle and the central bore  52  of the cannula has an inner diameter larger than the outer diameter of the inserter shaft  20 . In this way, the inserter shaft  20  extends into the central bore in the cannula as depicted in FIG.  1 . The inserter shaft  20  is extendable and retractable relative to the cannula  44 . 
     Preferably, the cannula  44  has two oppositely disposed slots  34  therein through which the suture  54  attached to the bone anchor passes. These slots reduce the possibility of the suture  54  becoming tangled. Preferably, the slots  34  in the cannula are aligned with and coextensive with the grooves  32  in the inserter shaft. 
     Alternatively, the sutures can be contained within the cannula and extend out another portion of the device such as the first handle  12 . 
     Preferably, the distal end  50  of the cannula has a sharp tip  56  to facilitate its use in piercing tissue. 
     As illustrated in FIGS. 1 and 2, in the embodiments in which the inserter shaft  20  is curved, the cannula  44  is preferably also curved in the same arc as the inserter shaft  20 . By curving the cannula  44 , the diameter of the cannula  44  can be reduced in comparison with embodiments in which the inserter shaft and the cannula are not curved. Thus, in the embodiments in which the inserter shaft  20  and cannula  44  are curved, the inner diameter of the cannula  44  is from about 0.1 inches to about 0.25 inches and the outer diameter of the cannula  44  is from about 0.14 inches to about 0.31 inches. Preferably the inner diameter of the cannula  44  is from about 0.15 inches to about 0.2 inches. In a highly preferred embodiment, the inner diameter of the cannula is 0.170 inches, the wall is about 0.02 inches, and the outer diameter is about 0.210 inches. These dimensions also apply to the devices in FIGS. 5 and 6 in which the inserter shaft and the cannula are also curved. 
     In a preferred embodiment, the cannula  44  has a protective cap  58  inside the central bore  52  and located at the distal end  50  of the cannula, as shown in FIGS. 2 and 3. The protective cap  58  may be made of a variety of materials, such as plastic, thermoplastic elastomers, PET, PETG, rubber material, vinyl, latex, acrylic, thermoset rubbers and silicone. Preferably, the protective cap  58  is made of silicone or plastic. 
     The internal protective cap  58  acts to shield the bone anchor  22  from contamination, e.g., from contact with microorganisms in the vagina which could cause infection if introduced into the pubic bone during implantation of the bone anchor. In one embodiment, the protective cap  58  has a vertical slit  60  and a horizontal slit  62  therein which intersect to form a cross. Alternatively, the protective cap  58  has slits three slits which intersect to form a Y. 
     In one embodiment, the slits  60  and  62  penetrate entirely through the material of the protective cap  58 , thereby dividing the protective cap into discrete segments. Preferably, the slits  60  and  62  are scored in the material of the protective cap  58  but do not extend entirely therethrough. 
     The slits  60  and  62  permit the bone anchor  22  to move through the protective cap  58  during implantation. In embodiments in which the slits  60  and  62  penetrate entirely through the material of the protective cap  58 , the bone anchor  22  forces the segments of the protective cap  58  to separate as the bone anchor  22  is extended through the protective cap  58 . The protective cap  58  remains in contact with the external surface of the bone anchor  22  as it is inserted into the bone, thereby shielding the bone anchor from contact with potentially infectious microorganisms in the vaginal wall. 
     The operation of the protective cap  58  in embodiments in which the slits  60  and  62  are scored in the protective cap is identical to that described above. However, in such embodiments, the tip of the bone anchor  22  pierces the material of the protective cap  58  as the bone anchor  22  is extended, thereby causing the protective cap  58  to separate into segments along the scores. 
     The proximal ends of the first and second handles,  14  and  38  respectively, are hingedly connected to permit them to move towards and away from one another. Any suitable type of hinge can be used, for example, this can be accomplished using a hinge  64  similar to that commonly found on doors as shown in FIGS. 1 and 2. Alternatively, a piece of rubber may be interposed between the first and second handles at their proximal ends  14  and  38  and secured thereto by bolts extending into holes in each of the handles. Those skilled in the art will appreciate that other means of hingedly connecting the first and second handles may be employed, and the present invention specifically contemplates embodiments in which such other hinging mechanisms are employed. 
     The first handle  12  and the second handle  36  are biased apart. In one embodiment, the biasing force is provided by a spring  66 , as discussed below. The spring  66  can be metal, resilient polymer, pneumatically driven, or of any other suitable design. However, those skilled in the art will appreciate that a number of other structures can be employed to achieve the same biasing effect. The present invention specifically contemplates such other means of biasing the handles apart. 
     When sufficient force is applied to the distal ends of the first and second handles ( 18  and  42 ) to overcome the resistance of the spring, the distal ends ( 18  and  42 ) of the first and second handles move closer together. In the position in which the distal ends of the first and second handles are maximally separated, the inserter shaft  20  and bone anchor  22  thereon are fully retracted inside the cannula  44 . As increasing force is applied to the handles and the distal ends approach one another, the inserter shaft  20  and bone anchor  22  thereon emerge from the distal end  50  of the cannula. At the point where the distal ends ( 18  and  42 ) of the first and second handles are touching, the inserter shaft  20  and bone anchor  22  thereon are maximally extended from the distal end  50  of the cannula. 
     At the point of maximum extension, the length of the inserter shaft  20  extending from the cannula  44  is from about 0.05 inches to about 0.8 inches. Preferably, at the position of maximum extension, the length of the inserter shaft  20  extending from the cannula  44  is about 0.1 inches to about 0.5 inches. More preferably, the length of the inserter shaft  20  extending from the cannula  44  at the position of maximum extension is 0.2 inches. 
     In the above embodiment, the bone anchor  22  is inserted in the bone by manually moving the inserter shaft  20  axially through the bore  52  in the cannula until the inserter shaft and bone anchor  22  thereon extend from the cannula  44 . However, those skilled in the art will appreciate that approaches other than manually moving the inserter shaft may also be used to implant the bone anchor into the bone. For example, the bone anchor  22  can be forced into the bone by applying sufficient pneumatic pressure through the inserter shaft to eject the bone anchor from the inserter shaft with sufficient force to implant the bone anchor in the bone. Alternatively, the bone anchor may be driven into the bone by a spring mechanism. 
     Preferably, the device further comprises a locking mechanism for locking the device in the position in which the inserter shaft is fully retracted within the cannula in order to avoid accidental insertion of the bone anchor into tissue. As those skilled in the art will appreciate, a variety of locking structures may be used to achieve such locking. 
     One exemplary locking mechanism is shown in FIG.  2 . The locking mechanism comprises a locking plate  15  slidably mounted over the first handle  12  and having a bore  68  therein The locking plate  15  is separated from the first handle  12  by a spacer  70  having an internally threaded bore  72  therein which is aligned with the bore  68  in the locking plate. The first handle  12  has an elongate hole  74  therein having a proximal end  75  and a distal end  77 . A locking screw  76  extends through the elongate hole  74  in the first handle and the bores  72 . 68  in the spacer  70  and locking plate  15 . The locking screw  76  is secured to the locking plate  15  by a nut  78 . 
     The second handle  36  has a bore  80  therethrough having a diameter larger than that of the head of the locking screw  76 . In the unlocked position, the bore  80  can be aligned with the locking screw  76  as shown in FIG. 4 thereby permitting the first handle  12  and the second handle  36  to be squeezed together such that the inserter shaft  20  extends from the cannula  44 . 
     As illustrated in FIG. 5, in the locked position, the locking plate  15  is positioned at the proximal end  75  of the elongate hole  74  in the first handle. In this position, the locking screw  76  is disposed between the first and second handles such that the head of the screw abuts the inner side of the second handle  36 , thereby preventing the first handle  12  and the second handle  36  from being squeezed together. 
     In an alternate embodiment, the bone anchor implantation device  110  may have a dual position lock permitting the device to be locked in a position in which the inserter shaft  120  is fully retracted within the cannula  144  or in a position in which the inserter shaft  120  is fully extended from the cannula  144 . In this embodiment, illustrated in FIG. 6 the bore  180  of the second handle  136  is keyhole shaped. The narrower part  121  of the keyhole shaped bore is sufficiently narrow to prevent the head of the locking screw  176  from passing therethrough. As illustrated in FIG. 7, when the locking plate  115  is positioned at the proximal end  175  of the elongate bore in the first handle, the head of the locking screw  176  is over the narrow part  121  of the keyhole shaped aperture  180 . As shown in FIG. 7, in this position the inner side of the head of locking screw  176  contacts the outer side of the second handle. The device is locked in the position in which the inserter shaft and bone anchor thereon are fully extended. 
     When the locking plate  115  is positioned at the distal end  177  of the elongate bore in the first handle, the head of locking screw  176  is aligned with the wide portion  123  of the keyhole shaped bore. The locking plate  115  can then be returned to the proximal end  175  of the elongate hole, such that the head of the locking screw  176  is disposed between the first handle  112  and the second handle  136  and the head of the locking screw  176  abuts the inner side of the second handle  136 , as shown in FIG.  8 . In this position the inserter shaft  120  is fully retracted and the first handle  112  and the second handle  136  cannot be squeezed together. 
     The above locking mechanisms may be used in the embodiments where the inserter shaft and cannula are straight. As those skilled in the art will appreciate, a variety of other locking structures may be used to achieve such dual position locking. Such other locking mechanisms are specifically contemplated by the present invention. 
     In the embodiments described above, the force biasing the two handles apart is preferably provided by a spring  66  disposed between two depressions  82  and  84  in the first handle  12  and the second handle  36 . In the embodiments described above, the spring  66  is located in the central regions  16  and  40  of the first and second handles. However, those skilled in the art will appreciate that the location of the spring is not critical to the operation of the present invention. Additionally, it will be appreciated that biasing members other than a spring may be employed to bias the handles apart. 
     Using the present bone anchor implantation device, the bone anchor is transvaginally introduced into the pubic bone as follows. 
     After making an incision in the anterior vaginal wall, the endopelvic fascia is accessed using techniques well known to those of skill in the art, such as with a conventional retractor. A Foley catheter may be introduced to assist in locating the bladder neck. The bone anchor implantation device is inserted into the vaginal introitus and the first desired site for bone anchor implantation is located by digital palpation of the urethra, pubic symphysis or other anatomical landmark or other techniques known to those of ordinary skill in the art. The device is locked in the position in which the inserter shaft is fully retracted during this procedure. 
     Once the desired site for bone anchor implantation is located, the sharp tip  56  on the distal end of the cannula is driven through the endopelvic fascia  17 . The pointed end of the cannula can also be employed to locate the desired implantation site by inserting the device into the vaginal introitus and through the incision, piercing the endopelvic fascia, and moving the cannula along the pubic bone  19  to the desired implantation site, as shown in FIG.  9 . 
     The device is then unlocked from the position in which the inserter shaft  20  is fully retracted. In the embodiment having a single position lock, the first and second handles ( 12  and  36 ) are pressed together with enough pressure to extend the inserter shaft  20  out of the cannula  44  and drive the bone anchor  22  into the posterior portion of the bone  19 . Alternatively, in the embodiment having a dual position lock, the device is locked in the position in which the inserter shaft  120  is fully extended from the cannula  144  and manual pressure is applied to drive the bone anchor  122  into the posterior portion of the pubic bone  19 . 
     As shown in FIG. 10, when the first and second handles are squeezed towards one another, the inserter shaft moves towards the bone  19 . The bone anchor  22  pierces the protective cap  58  which separates as the bone anchor  22  passes therethrough. The protective cap  58  shields the bone anchor  22  from contact with the vaginal tissue. 
     As shown in FIG. 11, when the inserter shaft  20  is extended beyond the distal tip of the cannula  56 , the bone anchor contacts the bone  19  and is driven therein. 
     The inserter shaft  20  is then retracted into the cannula  44 , leaving the bone anchor  22  implanted in the bone  19  with the attached suture  54  extending through the wound in the vaginal wall and the endopelvic fascia as shown in FIG.  12 . 
     The above site location and bone anchor implantation procedure is repeated to implant a second bone anchor on the opposite side of the urethra from the first bone anchor. 
     In one embodiment, the sutures are attached to a needle, looped back through the vaginal wall, and attached to tissue such as the endopelvic fascia or the vaginal wall so as to bias the tissue surrounding the urethra towards the urethra. The biasing force compresses or stabilizes the bladder neck thereby maintaining or improving urinary continence. 
     Alternatively, the sutures attached to the bone anchors can be attached to a sling which compresses or stabilizes the bladder neck. In such procedures, an incision is made midline to the urethra. An opening or pocket for receiving the sling is created in the tissue between the urethra and the upper vaginal wall. The bone anchor implantation device is inserted through the incision, into the pocket, and through the endopelvic fascia to contact the pubic bone. At least one bone anchor is inserted into the pubic bone on each side of the urethra. The sling is introduced into the opening or pocket and attached to the sutures. The tension on the sling provided by the sutures is adjusted to provide the appropriate biasing force to the urethra. 
     Example 1 describes one method of using the present bone anchor implantation device to compress or stabilize the bladder neck with sutures. It will be appreciated that the bone anchor implantation device can be used with other methods in which sutures compress or stabilize the bladder neck. 
     EXAMPLE 1 
     Compression or Stabilization of the Bladder Neck with Sutures 
     The bone anchor implantation device can be used in incontinence treatments in which the bladder neck is compressed or stabilized with sutures. A Foley catheter is inserted into the urethra to indicate its location. An incision is then made through the anterior vaginal wall, preferably approximately 1 cm lateral to midline and adjacent to the bladder neck. The vaginal wall is retracted to allow access to the endopelvic fascia. The bone anchor implantation device, having a bone anchor with sutures attached thereto releasably engaged with the inserter shaft, is introduced through the opening in the vaginal wall with the device locked in the position in which the inserter shaft is fully retracted within the cannula, and the sharp point is pressed through the fascia to contact the posterior pubic bone. Preferably, the anchor implantation site is located lateral to the symphysis pubis and cephalad to the inferior edge of the pubic bone. The anchor implantation site is located by palpating the inferior rim of the pubic bone and the symphysis pubis, moving laterally until the lower border of the obturator foremen is located. Preferably, the anchor is located from about 0.5 to 4 cm lateral to the symphysis pubis and from about 0.5 to 3 cm cephalad to the inferior edge. More preferably, the anchor implantation site is located approximately 1 cm lateral to the symphysis pubis and 1 cm cephalad to the inferior edge of the pubic bone. In addition, the anchor implantation site can be located on the pubic ramus. 
     The locking mechanism of the bone anchor implantation device is then placed in the unlocked position, and the two handles are squeezed together such that the inserter shaft is in the extended position. Alternatively, for devices having a dual position locking mechanism, the bone anchor may be exposed by locking the device in the position in which the inserter shaft is fully extended from the cannula. In either case, the anchor is driven into the pubic bone using manual pressure and opposing thumb pressure on the external pubic section if necessary. 
     The bone anchor implantation device is withdrawn, leaving the two free ends of the anchored suture exiting the endopelvic fascia  17 . A device such as a Mayo needle is then attached to one free end of the anchored suture and a “bite of fascia” is taken adjacent to the bladder neck. Preferably, the entry and exit points of the suture are adjacent to the bladder neck approximately 0.5 cm lateral to the urethra. This step is then repeated with the other free end of the suture, and the two ends are tied together. The vaginal wall incision is then closed. 
     Alternatively, the entry and exit points of the suture can be made as illustrated in FIG. 13 a  of copending U.S. application Ser. No. 08/042,739 filed Apr. 5, 1993, issued as U.S. Pat. No. 5,611,515. the disclosure of which is incorporated herein by reference. 
     The above procedure is then repeated on the opposite side of the urethra to complete the bladder neck suspension. The sutures are then appropriately tensioned. Appropriate tension is confirmed using well known means such as cystoscopy or a standard Q tip test. 
     EXAMPLE 2 
     Example 2 describes use of the bone anchor implantation device in a procedure in which the bladder neck is compressed or stabilized with a sling. However, it will be appreciated that the bone anchor implantation device can be used with other methods in which the bladder neck is compressed or stabilized with a sling. 
     Double Anchor Placement: for Sling or Bolster Procedure 
     The bone anchor implantation device can also be used in incontinence treatments in which the bladder neck is compressed or stabilized using a sling. Preferably, in such procedures two bone anchors are placed on either side of the urethra. However, one of ordinary skill in the art will appreciate that one or more than two bone anchors per side can be used. The procedure is performed as follows. 
     A Foley catheter is inserted into the urethra to indicate its location. Starting adjacent to the bladder neck on either side of the urethra, a 1 cm incision is made through the anterior vaginal wall approximately 1 cm lateral to and parallel to the midline of the urethra. The vaginal wall is retracted to allow access to the endopelvic fascia  17 . Blunt dissection is used to tunnel under the urethra and form a pocket for the sling. 
     The bone anchor implantation device is introduced through the opening in the vaginal wall with the device locked in the position in which the inserter shaft is fully retracted within the cannula, and the sharp point of the cannula is pressed through the fascia  17  near the distal end of the vaginal wall incision closer to the bladder neck, to contact the posterior aspect of the pubic bone. Preferably, the first anchor implant site is located lateral to the symphysis pubis and cephalad to the inferior edge of the pubic bone. More preferably, the first anchor implant site is located approximately 1 cm lateral to the symphysis pubis and 1 cm cephalad to the inferior edge of the pubic bone. 
     The locking mechanism of the bone anchor implantation device is then placed in the unlocked position, and the two handles are squeezed together to expose the anchor. Alternatively, for devices having a dual position locking mechanism, the bone anchor may be exposed by locking the device in the position in which the inserter shaft is fully extended from the cannula The anchor is driven into the pubic bone using manual pressure and opposing thumb pressure on the external pubic region if necessary. 
     The bone anchor implantation device is withdrawn leaving the two free ends of suture exiting the endopelvic fascia. 
     The above bone anchor implantation procedure is repeated to introduce a second anchor on the same side of the urethra as the first anchor. The second anchor implant site is located by palpating the obturator foremen in the pelvis just cephalad to the ramus. For implantation of the second anchor, the fascial tissue near the proximal end of the vaginal wall incision farther from the bladder neck is pierced. The second anchor is implanted on the superior (cephalad) aspect of the ramus. 
     The bone anchor implantation device is removed as before trailing the two free ends of each suture from the vaginal wall incision. 
     The above procedures for implantation of the first and second anchors are repeated on the opposite side of the urethra. 
     The sling is then positioned in the pocket under the urethra The free ends of suture from the two anchors on each side of the urethra are then tied to the corresponding corners of the sling. The sutures are then tied off with the appropriate amount of tension to suspend or stabilize the bladder neck. The vaginal wall incisions are then closed on each side. 
     Alternatively, the above procedure can also be utilized in techniques in which only a single bone anchor is inserted on either side of the urethra. Preferably, in such procedures the anchor implantation site is located approximately 1 cm lateral to the symphysis pubis and 1 cm cephalad to the inferior edge of the pubic bone. More preferably, the anchor implantation site is located approximately 1 cm lateral to the symphysis pubis and 1 cm cephalad to the inferior edge of the pubic bone. 
     Bone Anchor Implantation Device with Hooked Shaft 
     In another embodiment, the anchor implantation device of the present invention has a hooked shaft with a bone anchor mount for releasably engaging a bone anchor on the distal end of the shaft. This embodiment reduces the amount of force required to drive the bone anchor into the bone by utilizing the patient&#39;s body weight to provide an opposing force. 
     In this embodiment, the anchor implantation device comprises a handle, a hooked shaft secured to the handle and a bone anchor mount adapted to releasably engage a bone anchor attached to the distal end of the shaft. The bone anchor mount generally points toward the handle, such that the user can drive the bone anchor into the bone by simply pulling back on the handle and using the patient&#39;s body weight to provide an opposing force. Preferably, the longitudinal axis of the bone anchor mount is aligned with the longitudinal axis of the handle. Preferably, a protective sheath is attached to the bone anchor mount such that the bone anchor releasably engaged to the bone anchor mount is enclosed within the protective sheath and isolated from tissue contact during placement of the device. 
     A representative anchor implantation device having a hooked shaft is shown in FIG.  13 . As illustrated in FIG. 13, the anchor implantation device  210  has a handle  212  having a proximal end  214  and a distal end  216 . The handle  212  may be made of a variety of materials, such as plastic or metal. 
     The shaft  220  may be made of a variety of materials such as stainless steel engineering plastics, fiber-bearing components, or other materials. Preferably, the shaft is made of stainless steel. 
     In the embodiment of the bone anchor implantation device shown in FIG. 13, shaft  220  comprises a straight proximal section  222 , a first generally curved section  224  distal to the straight proximal section, a second generally curved section  226  distal to the first curved section, a third generally curved section  228  distal to the second curved section, and a fourth generally curved section  230  distal to the third curved section. However, one of skill in the art would appreciate that the shaft could also comprise a series of straight segments angled relative to one another to form a hook. 
     The straight proximal section  222  of the shaft  220  has an annular shoulder  232  which abuts the distal end  216  of the handle. The straight proximal section  222  passes through a lumen (not shown) extending through the handle. The proximal end of the straight proximal section  222  has a threaded bore which is adapted to receive a screw  236  which secures the shaft  220  to the handle. If desired, a washer (not shown) may be placed between the proximal end  214  of the handle and the screw  236 . 
     While one means of securing the shaft  220  to the handle  212  was described above, those skilled in the art will appreciate that a variety of other means may be employed. For example, a plastic handle may be formed over the shaft such that the shaft is integral with the handle. 
     The straight proximal section  222  of the shaft  220  may be from about 3 inches to about 6 inches in length. Preferably, the straight proximal section  222  is from about 4 inches to about 5 inches in length. More preferably, the straight proximal section  222  is about 4.5 inches in length. 
     The handle  212  defines an axis at the proximal end of the anchor implantation device  210 , and then moving distally from the handle  212  the shaft  220  first curves away from the axis of the handle and then back toward the axis of the handle  212 . The distal end of the shaft  220  preferably is located in the vicinity of the axis of the handle  212 . In some preferred embodiments, the shaft  220  at the distal end can be generally perpendicular to the axis of the handle or can actually be curving back toward the handle  212 . Preferably, the distance from the distal end of the handle  212  to the tip of the tapered bone anchor receptacle  246  measured along the longitudinal axis of the handle  212  is about 3⅜ inches. Preferably, the distance from the distal end of the handle  212  to the distal end of the bone anchor mount  238  is about 4 inches. Preferably, the distance of a line perpendicular to the longitudinal axis of the handle  212  extending from the bottom of the third curved section  228  is about 2 inches. 
     Referring to FIGS. 13-16, a bone anchor mount  238  is attached to the distal end  240  of the fourth curved section  230  of the shaft  220 . The bone anchor mount  238  may be oriented at an angle from about 60° to about 120° relative to the distal end  240  of the fourth curved section. Preferably, the bone anchor mount  238  is oriented at an angle from about 80° to about 100° relative to the distal end  240  of the fourth curved section. More preferably, the bone anchor mount  238  is oriented at an angle of approximately 90° relative to the distal end  240  of the fourth curved section, as illustrated in FIG.  13 . 
     The bone anchor mount comprises an outer cylinder  242 , an inner cylinder  244 , and a tapered bone anchor receptacle  246  for releasably engaging a bone anchor  248 . As was the case with the two handle bone anchor implantation device discussed above, a variety of bone anchors can also be used with the bone anchor implantation device having a hooked shaft. Preferably, the bone anchor used with the hooked shaft device is the bone anchor disclosed in the above incorporated published PCT application WO 95/16399. 
     In any event, it is preferred that the bone anchor mount  238  and the bone anchor receptacle  246  are oriented so that the bone anchor  248  is pointed in the general direction of the handle  212 . In one preferred embodiment, the axis of the bone anchor  248  is generally aligned with the axis of the handle  212 , with the bone anchor pointed toward the handle  212 . 
     The bone anchor mount  238  may be fabricated from the same materials as the shaft  220  and may be attached to the shaft  220  by a variety of methods known to those skilled in the art, such as brazing. As best shown in FIG. 15 the distal end  250  of the outer cylinder  242  has a pair of holes  252  therein sized to accommodate a suture  254 . 
     The outer cylinder  242  may have a diameter from about 0.18 inches to about 0.6 inches. Preferably, the outer cylinder  242  has a diameter from about 0.25 inches to about 0.5 inches. More preferably, the outer cylinder  242  has a diameter of about 0.375 inches. 
     As best shown in the cross section of FIG. 16, the outer cylinder  242  has a cavity  258  formed therein, creating a cup in the proximal region of the outer cylinder  242 . The proximal end  260  of the outer cylinder  242  has an annular shoulder  262  thereon. 
     The inner cylinder  244  is connected to the outer cylinder  242  and extends into the cavity  258  as best shown in FIG.  16 . The inner cylinder  244  may be connected to the outer cylinder  242  in a variety of ways known to those skilled in the art. For example, the inner cylinder  244  may be fused to the outer cylinder  242 . As best shown in FIG. 15, the inner cylinder  244  has grooves  264  therein adapted to accommodate the suture  254 . 
     A tapered bone anchor receptacle  246  extends from the proximal end  266  of the inner cylinder  244 . The tapered bone anchor receptacle  246  has grooves  268  therein adapted to accommodate the suture  254 . 
     The tapered bone anchor receptacle  246  may extend from the proximal end  266  of the inner cylinder  244  by a distance of from about 0.3 inches to about 0.7 inches. Preferably, the tapered bone anchor receptacle  246  extends from the proximal end  266  of the inner cylinder  244  by a distance of from about 0.4 inches to about 0.6 inches. More preferably, the tapered bone anchor receptacle  246  extends from the proximal end  266  of the inner cylinder  244  by a distance of about 0.5 inches. 
     The distal end  270  of the tapered bone anchor receptacle  246  preferably has a width smaller than that of the proximal end  266  of the inner cylinder  244 . This configuration produces a shoulder  272  which may serve as a depth stop to ensure that the bone anchor  248  is driven into the bone to the desired depth. 
     The distal end  270  of the tapered bone anchor receptacle  246  may be from about 0.08 inches to about 0.12 inches in width. Preferably, the distal end  270  of the tapered bone anchor receptacle  246  is from about 0.09 inches to about 0.110 inches in width. More preferably, the distal end of the tapered bone anchor receptacle  246  is 0.1 inches in width. 
     The proximal end  274  of the tapered bone anchor receptacle  246  may be from about 0.110 inches to about 0.15 inches in width. Preferably, the proximal end  274  of the tapered bone anchor receptacle  246  is from about 0.12 inches to about 0.14 inches in width. More preferably, the proximal end  274  of the tapered bone anchor receptacle  246  is 0.13 inches in width. 
     The proximal end  274  of the tapered bone anchor receptacle  246  may have a variety of cross sectional shapes adapted to releasably engage the bone anchor  248 . For example, the proximal end  274  of the tapered bone anchor receptacle  246  may be square, rectangular, pentagonal, triangular or hexagonal in cross section. 
     As depicted in FIGS. 14-16, the tapered bone anchor receptacle  246  may have a notch  276  therein in which the bone anchor  248  is releasably seated. 
     Alternatively, the outer cylinder, inner cylinder, and tapered bone anchor receptacle may be a single integral component. 
     Preferably, the bone anchor implantation device has a protective sheath connected to the bone anchor mount which protects the point of the bone anchor from tissue contact during placement of the device and also protects the bone anchor from contacting potentially infectious microorganisms. 
     One embodiment of the protective sheath  278  is shown in FIGS. 13-16. In this embodiment, the protective sheath  278  comprises a first telescoping cylinder  280  and a second telescoping cylinder  282 . A spring  284  biases the first telescoping cylinder  280  and the second telescoping cylinder  282  to a position in which they extend from the outer cylinder  242  and cover the bone anchor  248 . 
     The first and second telescoping cylinders  280 ,  282  may be made of a variety of materials such as stainless steel or plastic. Preferably, the first and second telescoping cylinders  280 ,  282  are made of stainless steel. 
     The first telescoping cylinder  280  has a lumen  286  extending therethrough. The first telescoping  280  cylinder has a first shoulder  288  which engages shoulder  262  on the outer cylinder  242  and a second shoulder  290  which engages a first shoulder  292  on the second telescoping cylinder  282 . 
     The second.telescoping cylinder  282  has a first shoulder  292  which engages the second shoulder  290  on the first telescoping cylinder  280  as described above. A second shoulder  294  is located at the proximal end of the second telescoping cylinder  282  and engages the spring  284 . The second telescoping cylinder  282  also has a lumen  296  extending therethrough which is in fluid communication with the lumen  286  of the first telescoping cylinder  280  and the cavity  258  in the outer cylinder  242 . 
     The inner diameter of the first telescoping cylinder  280  is slightly larger than the outer diameter of the of the second telescoping cylinder  282  such that the second telescoping cylinder  282  can retract inside the first telescoping cylinder  280 . The first telescoping cylinder  280  and the second telescoping cylinder  282  can retract inside the cavity  258  of the outer cylinder  242 . 
     The first telescoping cylinder  280  may be from about 0.2 inches to about 0.3 inches in length, with an inner diameter of from about 0.27 inches to about 0.33 inches and an outer diameter of about 0.3 inches to about 0.36 inches. Preferably, the first telescoping cylinder  280  is from about 0.23 inches to about 0.27 inches in length, with an inner diameter of from about 0.29 inches to about 0.31 inches and an outer diameter of about 0.32 inches to about 0.34 inches. More preferably, the first telescoping cylinder  280  is about 0.25 inches in length, with an inner diameter of about 0.3 inches and an outer diameter of about 0.33 inches. 
     The second telescoping cylinder  282  may be from about 0.2 inches to about 0.3 inches in length, with an inner diameter of from about 0.22 inches to about 0.31 inches and an outer diameter of about 0.25 inches to about 0.35 inches. Preferably, the second telescoping cylinder  282  is from about 0.23 inches to about 0.27 inches in length, with an inner diameter of from about 0.24 inches to about 0.29 inches and an outer diameter of about 0.27 inches to about 0.33 inches. More preferably, the second telescoping cylinder  282  is about 0.25 inches in length, with an inner diameter of about 0.27 inches and an outer diameter of about 0.3 inches. 
     As illustrated in FIGS. 14-16, a spring  284  biases the first and second telescoping cylinders  280  and  282  towards a position in which the first telescoping cylinder  280  and the second telescoping cylinder  282  are extended from the outer cylinder  242 . 
     An alternative embodiment of the bone anchor implantation device  310  is shown in FIGS. 17-20. 
     As illustrated in FIGS. 17 and 18, the shaft  320  has a generally straight proximal section  399 , a first generally bent section  397 , a generally straight median section  395 , a second bent section  393 , a generally curved section  391 , and a distal generally straight section  389 . 
     The straight proximal section  399  may be from about 3.0 inches to about 6.0 inches in length. Preferably, the straight proximal section  399  is from about 4.0 inches to about 5.0 inches in length. More preferably, the straight proximal section  399  is about 4.5 inches in length. 
     The first bent section  397  may be from about 1.0 inches to about 3.0 inches in length. Preferably, the first bent section  397  is from about 1.5 inches to about 2.5 inches in length. More preferably, the first bent section  397  is about 2 inches in length. 
     The first bent section  397  may bend at an angle of from about 35° to about 55° relative to the straight proximal section  399 . Preferably, the first bent section  397  bends at an angle of from about 40° to about 50° relative to the straight proximal section  399 . More preferably, the first bent section  397  bends at an angle of about 45° relative to the straight proximal section  399 . 
     The straight median section  395  may be from about 2 inches to about 4 inches in length. Preferably, the straight median section  395  is from about 2.5 inches to about 3.5 inches in length. More preferably, the straight median section  395  is about 3 inches in length. 
     The second bent section  393  may be from about 0.5 inches to about 2.5 inches in length. Preferably, the second bent section  393  is from about 1.0 inches to about 2.0 inches in length. More preferably, the second bent section  393  is about 1.5 inches in length. 
     The second bent section  393  may bend at an angle of from about 125° to about 145° relative to the straight median section  395 . Preferably, the second bent section  393  bends at an angle of from about 130° to about 140° relative to the straight median section  395 . More preferably, the second bent section  393  bends at an angle of about 135° relative to the straight median section  395 . 
     The curved section  391  may curve through an arc of from about 70° to about 110° with a radius from about 0.2 inches to about 0.6 inches. Preferably, the curved section curves  391  through an arc of from about 80° to about 100° with a radius from about 0.3 inches to about 0.5 inches. More preferably, the curved section  391  curves through an arc of about 90° with a radius of 0.4 inches. 
     The distal straight section  389  may be from about 0.5 inches to about 0.9 inches in length. Preferably, the distal straight section  389  is from about 0.6 inches to about 0.8 inches in length. More preferably, the distal straight section  389  is about 0.7 inches in length. 
     The shaft  320  has a lumen extending therethrough. The lumen may have a diameter from about 0.03 inches to about 0.07 inches and the shaft  320  may have an outer diameter from about 0.2 inches to about 0.3 inches. Preferably, the lumen has a diameter from about 0.04 inches to about 0.06 inches and the shaft  320  has an outer diameter from about 0.24 inches to about 0.26 inches. More preferably, the lumen has a diameter of about 0.05 inches and the shaft  320  has an outer diameter of about 0.250 inches. 
     Preferably, the shaft  320  has an insert  387  therein with a lumen  385  extending therethrough as best illustrated in the cross section of FIG.  19 . The insert  387  may be made of a variety of materials such as stainless steel or plastic. 
     The insert  387  has an outer diameter approximately. that of the diameter of the lumen in the shaft such that the insert  387  fits snugly within the lumen of the shaft. The insert  387  may have an outer diameter from about 0.2 inches to about 0.3 inches. Preferably, the insert  387  has an outer diameter from about 0.21 inches to about 0.27 inches. More preferably, the insert  387  has an outer diameter of about 0.23 inches. 
     The insert  387  has a lumen  385  extending therethrough having a diameter large enough to accommodate a suture  354 . The diameter of the lumen  385  may be from about 0.02 inches to about 0.100 inches. Preferably, the diameter of the lumen  385  is from about 0.04 inches to about 0.08 inches. More preferably, the diameter of the lumen  385  is about 0.06 inches. 
     As illustrated in FIGS. 17,  18  and  20 , the shaft  320  has a bore therein which is large enough to permit the suture  354  to exit from the shaft  320 . In the embodiment shown in FIGS. 17,  18  and  20 , the bore is located in the straight median section  395  at a position in which it is located outside of the patient&#39;s body when the bone anchor  348  has been inserted into the patient&#39;s bone. However, those skilled in the art will appreciate that the bore may be located in other locations such as the first bent section  397 . 
     As illustrated in FIGS. 17 and 20, the shaft  320  extends through a lumen  383  in the handle  312 . The lumen  383  has a narrow distal section  381  having a diameter slightly larger thin the outer diameter of the shaft  320  and a wider proximal section  373  adapted to receive a spring  371 . 
     The shaft  320  passes through the interior of the spring  371  as depicted in FIGS. 17 and 20. The distal end of the spring  371  contacts the distal end of the wider proximal section  373  of the lumen. The proximal end of the spring contacts a plug  369 . The plug  369  has a lumen through which the shaft  320  passes and a bore adapted to receive a screw  367 . The screw  367  passes through the bore in the plug  369  and a bore in the shaft  320  which is aligned with the bore in the plug, thereby securing the shaft  320  to the plug  369 . 
     The resistance of the spring  371  is selected to be equal to the force with which the bone anchor  348  is to be driven into the bone. For example, where the bone anchor  348  is to be driven into the bone by applying 20 pounds of force, the spring  371  is a 20 pound spring. The spring indicates when the desired amount of force has been applied because the user can sense when the spring has been completely compressed. 
     The spring  371  may have a resistance of from about 5 to about 35 pounds. Preferably, the spring  371  has a resistance from about 15 to about 25 pounds. More preferably, the spring  371  has a resistance of 20 pounds. 
     Those skilled in the art will appreciate that the anchor implantation device shown in FIGS. 13-16 may also be adapted to include a force indicating spring in the handle. 
     As illustrated in FIGS. 17,  18  and  20 , a bone anchor mount  338  and a protective sheath  378  as described above with respect to the embodiment of FIGS. 13-16 are attached to the end of the distal straight section  389 . 
     The hooked bone anchor implantation devices  210 ,  310  are used as follows. An incision in the anterior vaginal wall is made as described above. The site for bone anchor implantation is located by palpation as described above. 
     The hooked bone anchor implantation device  210 ,  310  is inserted into the vagina as shown in FIGS. 17 and 21 with the patient in the lithotomy position and the surgeon located between the patient&#39;s legs. The shaft  220 ,  320  is inserted through the incision and the and the protective sheath  278 ,  378  is positioned such that the proximal end of the second telescoping cylinder  282 ,  382  contacts the pubic bone  219 ,  319  as shown in FIGS. 17,  21 , and  23 . At this time, the first and second telescoping cylinders  280 ,  380 ,  282 ,  382  are biased to a position in which they extend from the outer cylinder  242 ,  342  to cover the bone anchor. The bone anchor is inserted into the bone by applying a retrograde force to the bone anchor. The retrograde force can be applied in a number of ways as will be apparent to one of skill in the art. Preferably, the bone anchor is implanted by pulling the handle. For example, the handle may be pulled in a retrograde direction (toward the user) to implant the anchor as shown in FIGS. 20 and 22. As the device is pulled in a retrograde motion, the first and second telescoping cylinders  280 ,  282 ,  380 ,  382  retract inside the cavity  258 ,  358  of the outer cylinder as shown in FIGS. 20,  22  and  24  and the bone anchor  248 ,  348  is driven into the pubic bone  219 ,  319 . Because the patient&#39;s body weight provides an opposing force, the user need only apply a small amount of force, such as 10-20 pounds, in order to drive the bone anchor  248 ,  348  into the bone  219 ,  319 . The device  210 ,  310  is then pushed away from the implanted anchor to disengage the device from the anchor. The device is then removed from the vagina, leaving the bone anchor  248 ,  319  in the bone  219 ,  319  with the suture extending therefrom. The bladder neck is then compressed, suspended or stabilized using the suture(s) extending from the bone anchor(s) as described above. 
     As shown in FIG. 20, in the device  310  having a spring  371  inside the handle  312 , the spring  371  is compressed when the handle is pulled in a retrograde direction to drive the bone anchor into the bone. In this embodiment, the user can detect when the spring  371  has been completely compressed, or compressed by a predetermined amount, indicating that the desired amount of force for driving the bone anchor into the bone has been applied. 
     Although this invention has been described in terms of certain preferred embodiments, other embodiments which will be apparent to those of ordinary skill in the art in view of the disclosure herein are also within the scope of this invention. Accordingly, the scope of the invention is intended to be defined only by reference to the appended claims.