Abstract:
A method for impacting a suture anchor into bone comprises providing an implantable suture anchor and providing an impactor device for impacting the suture anchor into the bone. The suture anchor is coupled to a distal portion of the impactor device. Positioning the suture anchor engages the anchor with the bone at an implantation site, and powering the impactor device impacts the suture anchor thereby implanting the suture anchor into the bone. The frequency of impaction is less than 20 KHz. The impactor device is then decoupled from the suture anchor, and the impactor device may be removed from the implantation site.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present application is a non-provisional of, and claims the benefit of priority of U.S. Provisional Patent Application No. 61/108,420 (Attorney Docket No. 020979-003900US), filed Oct. 24, 2008, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present disclosure relates to medical devices, systems and methods, and more specifically to methods, systems and devices used for anchoring suture and delivery of suture anchors. 
         [0004]    Soft tissue such as tendons, ligaments and cartilage are generally attached to bone by small collagenous fibers which are strong, but which nevertheless still can tear due to wear or disease. Examples of musculoskeletal disease include a torn rotator cuff as well as a torn labrum in the acetabular rim of a hip joint or the glenoid rim in a shoulder joint. 
         [0005]    Thus, treatment of musculoskeletal disease may involve reattachment of torn ligaments, tendons or other tissue to bone. This may require the placement of suture anchors in the humeral head for reattachment of a torn rotator cuff, placement of suture anchors in the acetabular or glenoid rim for reattachment of the torn labrum, placement of tacks to attach labral tissue to the glenoid rim, placement of screws in the vertebral bodies to attach cervical plates for spinal fusion, placement of screws in small joint bones for stabilizing reduced fractures, etc. A suture anchor is a device which allows a suture to be attached to tissue such as bone. Suture anchors may include screws or other tubular fasteners which are inserted into the bone and anchored in place. After insertion of the anchor, the tissue to be repaired is captured by a suture, the suture is attached to the anchor (if not already pre-attached), tension is adjusted, and then the suture is often knotted so that the tissue is secured in a desired position. 
         [0006]    Delivery of a suture anchor to a treatment site can be time consuming and challenging to undertake in the tight space encountered during endoscopic surgery and sometimes even in conventional open surgery. In most surgical procedures, a pilot hole is drilled at the implantation site prior to screwing in the device. In other cases a self-tapping device tip is used to screw in the device without a pilot hole. Alternatively, ultrasonic energy has been proposed in embedding bone anchors in bony tissue without pre-drilling a pilot hole. These methods of implanting a device in bone tissue, while commonly used in surgery today, are not optimal. Pre-drilling a pilot hole prior to placing the device requires the surgeon to exchange tools through the cannula and to locate the pilot hole after introducing the implant in the arthroscopic field. Self-tapping devices are limited to use at sites with the appropriate thickness of cortical bone. Ultrasonic energy based devices are susceptible to large energy losses with minor changes in device configuration, and rely on ultrasonic energy sources which can be expensive. It would therefore be desirable to provide a suture anchor system that provides easy access to the treatment site and that can easily and accurately deliver a suture anchor to a desired location. 
         [0007]    In a particular application, treating musculoskeletal disease in a hip joint can be especially challenging. The hip joint is a deep joint surrounded by a blanket of ligaments and tendons that cover the joint, forming a sealed capsule. The capsule is very tight thereby making it difficult to advance surgical instruments past the capsule into the joint space. Also, because the hip joint is a deep joint, delivery of surgical instruments far into the joint space while still allowing control of the working portions of the instrument from outside the body can be challenging. Additionally, the working space in the joint itself is very small and thus there is little room for repairing the joint, such as when reattaching a torn labrum to the acetabular rim. Thus, the suture anchor tool must be small enough to fit in the limited space. Moreover, when treating a torn labrum, the suture anchor must be small enough to be inserted into the healthy rim of bone with adequate purchase, and the anchor also must be short enough so that it does not protrude through the bone into the articular surface of the joint (e.g. the acetabulum). Thus, the anchor delivery instrument must also be able to hold and deliver suture anchors having a small diameter and small length. 
         [0008]    Therefore, it would be desirable to provide improved suture anchors and suture anchor delivery instruments that overcome some of the aforementioned challenges. Such suture anchors and delivery instruments are preferably suited to arthroscopic procedures, and in particular labral repair in the hip. At least some of these objectives will be met by the disclosure described below. 
         [0009]    2. Description of the Background Art 
         [0010]    Patents disclosing suture anchoring devices and related technologies include U.S. Pat. Nos. 7,566,339; 7,390,329; 7,309,337; 7,144,415; 7,083,638; 6,986,781; 6,855,157; 6,770,076; 6,767,037; 6,656,183; 6,652,561; 6,066,160; 6,045,574; 5,810,848; 5,728,136; 5,702,397; 5,683,419; 5,647,874; 5,630,824; 5,601,557; 5,584,835; 5,569,306; 5,520,700; 5,486,197; 5,464,427; 5,417,691; and 5,383,905. Patent publications disclosing such devices include U.S. Patent Publication Nos. 2009/0069845; 2008/0188854; and 2008/0054814. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    The current invention comprises surgical devices and methods to treat various soft tissue and joint diseases, and more specifically relates to suture anchors and suture anchor delivery instruments used in the treatment of bone, cartilage, muscle, ligament, tendon and other musculoskeletal structures. 
         [0012]    In a first aspect of the present invention, a method for impacting a suture anchor into bone comprises providing an implantable suture anchor, and providing an impactor device for impacting the suture anchor into the bone. The suture anchor is coupled to a distal portion of the impactor device. Positioning the suture anchor engages the suture anchor with the bone at an implantation site, and powering the impactor device impacts the suture anchor thereby implanting the suture anchor into the bone. The frequency of impaction is less than 20 KHz. The impactor device is decoupled from the suture anchor and then the impactor device is removed from the implantation site. 
         [0013]    The suture anchor may pass through adjacent musculoskeletal tissues and may attach the adjacent musculoskeletal tissues to the bone. The adjacent musculoskeletal tissues may comprise bony tissues or soft tissues. The suture anchor may include one or more lengths of suture. Powering of the impactor device may comprise pneumatically, electrically, mechanically, or magnetically actuating the impactor device. The impactor device may impact the anchor when powered so as to linearly, rotationally, or linearly and rotationally drive the suture anchor into the bone. The frequency of impaction may be less than 1 KHz. The impaction may have an amplitude of 1,000 micrometers or less per impact. 
         [0014]    The method may further comprise expanding a portion of the suture anchor radially outward so as to firmly engage the suture anchor with the bone. The suture anchor may comprise a plurality of fingers, and expanding a portion of the suture anchor may comprise releasing a constraint from the fingers so as to allow the fingers to radially expand outward. The impactor device may comprise an elongate tubular shaft and the step of decoupling may comprise advancing the suture anchor axially away from a distal portion of the shaft. The method may also comprise cooling the suture anchor or the implantation site with a fluid. 
         [0015]    In another aspect of the present invention, a suture anchor delivery system comprises an implantable suture anchor having a longitudinal axis and a plurality of fingers circumferentially disposed therearound. The fingers have a constrained configuration and an unconstrained configuration. In the constrained configuration the fingers are substantially parallel with the longitudinal axis, and in the unconstrained configuration, the fingers expand radially outward. The system also includes an impactor device for impacting the suture anchor into bone. The suture anchor is releasably coupled to a distal portion of the impactor device. 
         [0016]    In a further aspect, the invention provides a suture anchor formed of shape memory material and having an unbiased configuration adapted to securely fix the anchor in bone or other tissue. The suture anchor is deformable into a configuration adapted for delivery into the bone or tissue, from which it may be released so that it returns toward its unbiased configuration thereby anchoring the anchor in the bone or tissue. In various embodiments, the anchor may have in its unbiased configuration a plurality of resilient fingers that extend radially outward, a curved shape formed around a transverse axis, two or more wings that flare outwardly in the proximal direction, or two or more longitudinal divisions defining a plurality of axial elements that bow or deflect outwardly. Other structures are disclosed herein. 
         [0017]    In another aspect, the invention provides a suture anchor having a tapered tip adapted for being driven into bone, with or without a pre-drilled hole, a shaft extending proximally from the tip, and a means for attaching a suture to the shaft. The tip, the shaft, or both are cross-shaped in cross section. 
         [0018]    The suture anchor may comprise a textured outer surface to allow for bone ingrowth. The suture anchor may also comprise a length of suture coupled thereto. The impactor device may impact the suture anchor at a frequency of less than 20 KHz, or at a frequency of less than 1 KHz. the impactor device may comprise an actuation mechanism for impacting the suture anchor that is pneumatically, electrically, magnetically, or mechanically actuated. The impactor device may impact the suture anchor and drive the anchor into the bone or other tissue in a linear, rotational, or linear and rotational manner. The impactor device may impact the suture anchor with an impaction having an amplitude of 1,000 micrometers or less per impact. The system may further comprise a cooling system for cooling the impactor device and suture anchor during impaction. The cooling system may comprise a cooling fluid. 
         [0019]    These and other embodiments are described in further detail in the following description related to the appended drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a sectional view of an anchor loaded in the distal end of an anchor driver and placed through a cannula. 
           [0021]      FIG. 2  is a sectional view of a flat anchor loaded into the distal end of an anchor driver with a stabilization sleeve. 
           [0022]      FIG. 3  is a sectional view of a round anchor loaded into the distal end of an anchor driver with a tubular profile. 
           [0023]      FIG. 4  is a sectional view of the body of a pneumatic powered impactor. 
           [0024]      FIG. 5  is a sectional view of the body of a electromechanically powered impactor. 
           [0025]      FIG. 6  is a sectional view of the body of an impactor with a rotary mechanism. 
           [0026]      FIG. 7  is an example of an anchor. 
           [0027]      FIGS. 8A-8D  are examples of anchors. 
           [0028]      FIGS. 9A-9B  are examples of anchor in a constrained and deployed configuration. 
           [0029]      FIGS. 10A-10B  are examples of a device for sutureless attachment of tissue to bone in a constrained and deployed configuration. 
           [0030]      FIGS. 11A-11B  are examples of a curved anchor in a constrained and deployed configuration. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    The devices and methods disclosed herein address at least some of the limitations of current methods of implanting devices into bony tissue. The method involves driving the device into bony tissue by impaction whereby, an impactor drives the implant into bone at frequencies between 10 and 20 KHz, preferably between 20 and 1000 Hz, most preferably between 30 and 500 Hz; and at amplitudes of 100 to 1000μ, preferably 200-750μ, most preferably 300-500μ. The implantable device may be loaded into the distal end of the impactor such that the distal end of the impactor and the attached device may be introduced into an arthroscopic field through a cannula. 
         [0032]      FIG. 1 , shows a sectional view of implant  103  loaded into an impactor  102  and introduced through a cannula  103 . Implant  101  is located at the distal end of impactor assembly  102 . The assembly  102  is introduced down the bore of cannula  103  and placed in the proximity of bony structure  104 . Having been placed at the surface of bony structure  104  the impactor  102  is energized and the implant  101  is driven into the bone. Channel  105  extends transversely through the implant  103  and allows a suture to be secured thereto. During the impaction period, contact between the tip of the device and the bony tissue is maintained manually by the surgeon. 
         [0033]    In one exemplary embodiment the implant is impacted into the bone by application of force onto the proximal surface of the implant. Referring to  FIG. 2 , implant  201  is impacted by impactor member  202 . This allows the implant  201  to be constructed with substantially consistent cross sections. Sleeve  203  can move relative to the implant  201  and impactor member  202  while remaining concentric and serves to stabilize and guide the implant  201  while the implant  201  is being impacted into the bone. 
         [0034]    In another embodiment the implant is configured with a stepped shoulder region  303  along the length of the body suitable for applying impaction force.  FIG. 3  shows a cross sectional view of anchor  301  which has a round cross section and interfaces with the distal end of the impactor  302 . The distal end of the impactor  302  is generally round and hollow. The distal end of the impactor  302  which interfaces with the anchor device  301  could be of varying length to enable introduction through cannulas used to access joint spaces in the shoulder, knee, hip etc. The impactor  302  may also be loaded with multiple devices. 
         [0035]    At the frequencies utilized during deployment of anchors, the amount of energy loss by heat dissipation is low. However, the distal end of the impactor may optionally be designed to circulate cold fluid to regulate the temperature of the impactor tip and the implant. Other forms of cooling well know in the art may also be used in conjuction with the impactor. 
         [0036]    The frequency and amplitude of the impactor may be adjusted to optimize the implantation process depending on the size of the implant, the design of the implant, as well as the properties of bone at the implant site, etc. 
         [0037]    In another embodiment, the impactor is powered by compressed gas which is commonly available in operating rooms.  FIG. 4  shows a cutaway view of one embodiment of a pneumatic driver used for placing devices in bony tissue. Shuttle element  401  is cycled back and forth based on air pressure by selectively pressurizing and releasing pressure in chamber  402  through the cyclic motion of shuttle  401  relative to ports  403  and  404 . As the shuttle moves port  403  is selectively covered or uncovered causing the shuttle to reverse direction based on the action of spring  405  which rebounds shuttle  401  back into the depressurized chamber  402 . At one end of the shuttle travel, the shuttle impacts active element  406  which is in contact with the proximal end of the device  407  thereby transmitting the energy from the shuttle  401  to the device  407  with each cycle. At the end of the cycle, the spring  408  returns the active element  406  back to its original position. Those skilled in the art will appreciate that the system shown in  FIG. 4  is an exemplary system and the same effect could be accomplished with a variety of pressured driving mechanisms. 
         [0038]    In another embodiment, the impactor could be designed to operate using a mechanical shuttle mechanism driven by an electromagnetic field.  FIG. 5  shows a sectional view of an instrument used for driving devices into bony tissue. Shuttle element  501  may be composed of any ferromagnetic material and is cycled back and forth based on the magnetic field created by a coil  502  which is connected to a signal generator capable of generating alternating current. At one end of the shuttle travel, the shuttle impacts active element  503  which is in contact with the proximal end of the device  504  thereby transmitting the energy from the shuttle to the device with each cycle. Those skilled in the art will appreciate this system shown in  FIG. 5  is an exemplary system and the same effect could be accomplished with a variety of electromechanical driving mechanisms. 
         [0039]    In another embodiment, the impactor could be designed to operate using mechanical means whereby rotary motion is converted to linear motion.  FIG. 6  shows a sectional view of an instrument used for driving devices into bony tissue. Cable driven cam  601  is designed with a circular ramp  602  that interfaces with mating ramp  603  that is part of shuttle  605  that does not rotate due to pin  604  and slot in  603 . Rotation of ramp  602  causes mating ramp  603  to move in a reciprocating fashion which is transmitted to the active element  606  which in turn imparts its energy to implant  608 . Shuttle  605  returns to its original position once ramps  602  and  603  have disengaged via the force applied by spring  607 . This allows active element  606  to return due to the force applied by spring  608 . Those skilled in the art will appreciate this system shown in  FIG. 6  is an exemplary system and the same effect could be accomplished with a variety of mechanisms that convert rotational motion into reciprocating motion. 
         [0040]    In all the embodiments described above, by altering the pressure, current, rotational speed etc., the frequency and amplitude of the impactor can be varied to enable the surgeon to select settings that are appropriate for various tissue properties (e.g.; cortical bone, cancellous bone, etc.) 
         [0041]    In addition to the embodiments described above, the impactor may have linear and rotational motion combined to create a reciprocating twisting motion. By creating a reciprocating twisting motion, devices may be driven in more securely into bony tissue, thereby increasing the stability of the implanted device. The amount of twisting motion may be varied based on the specific design and dimensions of the device.  FIG. 7  illustrates an exemplary embodiment of a suture anchor device  702  having a pointed distal tip  706  and a main shaft  704 . Both the main shaft  704  and the distal tip  706  have a twisted, helical-like configuration so that the anchor will rotate as it is being driven into the bone by an impactor having a reciprocating twisting motion. 
         [0042]    The impaction method has advantages that are not limited to a particular device design. For example, the implant may be cylindrical, flat, or a have a variety of other cross sections. Additionally the cross section may change along the length of the implant.  FIGS. 8A-8D  show a variety of anchor devices that may be useful in this application. The implant may be threaded or plain.  FIG. 8A  shows an anchor with a tip  801  which has a triangular pointed tip while the shank  802  has a substantially round cross section. Shank  802  has a hole  803  that passes through the shank allowing for attachment of a suture.  FIG. 8B  shows an anchor  810  having a rectangular cross section  812  resulting in a generally flat configuration.  FIG. 8C  shows an anchor  816  with a cross section generally described as a hollow tube and a suture S coupled thereto. In the embodiment shown in  FIG. 8C , wings or fingers  804  and  805  are active elements that deploy once the implant is released from the delivery instrument. For example wings or fingers  804 ,  805  may be fabricated from a superelastic material like Nitinol, spring temper stainless steel, a resilient polymer, or the wings may be fabricated from a shape memory alloy, such that once the anchor  816  is advanced from the delivery instrument and the wings  804 ,  805  become unconstrained, they spring open, radially outward. The wings help secure the anchor  816  into bone or other tissue. In alternative embodiments, the wings  804 ,  805  may be deformed into the flared radially outward position to help secure the anchor into the bone. For example, a plunger may be advanced into the center of the anchor thereby causing the wings  804 ,  805  to flare outward.  FIG. 8D  shows an anchor  814  with a tip  814 A and a shank  814 B having a generally X-shaped or cross-shaped cross section that may inserted into bone using the techniques described herein. In the embodiment shown, both the tip and the shank of anchor  814  have a cross-shape cross-section, although in other embodiments just the tip or just the shank may have a cross-shape. shank  814 B has a transverse hole through which a suture may be threaded. Other means of attachment of the suture to the shank may also be used. 
         [0043]    Additionally, the implant and driver could be designed such that a loaded implant constrained by the driver is placed at the implantation site. Following placement, the implant recovers to a pre-determined shape that enhances the anchoring of the implant in the bony tissue.  FIG. 9A  shows a cylindrically shaped tubular expandable anchor  906  in its loaded (constrained) condition. The anchor comprises a plurality of axially oriented slits  905  that form a plurality of axially oriented elements  901 . Element  901  is an active element that can be constrained to the profile of the non active portion of the implant  902 . Element  901  is replicated in a circular pattern around the periphery of the implant  906 . Conically shaped nosecone  903  is distal to the end of the driver instrument (not illustrated) while the shank is composed of active elements and non active portions  901  and  902  respectively. The anchor  906  is constrained in the delivery instrument.  FIG. 9B  shows the same anchor  906  in its deployed configuration after being released and unconstrained from the delivery instrument (not illustrated). Elements  901  are self-expanding and thus have moved to an expanded position to lock the anchor into the bony tissue. The elements  901  may be fabricated from self-expanding materials such as superelastic nitinol, shape memory alloys, spring temper metals, resilient polymers, or other resilient materials. Expansion element  901  causes a shortening of the overall anchor  906  length. In the case where there is a preloaded suture or soft tissue fixation element attached to  901 , this shortening of the anchoring element can be used as a tensioning means for the soft tissue fixation element. Tensioning the soft tissue fixation would provide improved coaptation of the soft tissue to the bone, and improve the repair. The degree of foreshortening can be programmed into the device by modifying one or a combination of the diameter of the distal driving (pointed) element of  901 , the length of the shaft of  901 , the diameter of the shaft of  901 , and the specific design of the cutouts  905  of  901 . 
         [0044]    Change in the implant after implantation could be based on the expansion of the body of the anchor as shown in  FIG. 9B  or by deployment of a fixation member from the body of the anchor as shown in  FIG. 8C . A combination of the expansion of the body of the anchor and deployment of members from the body could also be used. Expansion of the anchor could include mechanical means of expanding the anchor from a first configuration to a second configuration based on the malleability of the material or could be achieved through the use of self-expanding or shape memory materials. Deployment of fixation members may be achieved through various means including shape memory and mechanical means. The implants may include one or more sutures. The body of the implant may have holes to allow for bony in-growth into or across the implant. The surface of the implant may be textured or porous to allow for bone in-growth to enhance long term anchoring of the implant. The implant may be hollow to allow for bony in-growth within the implant. An advantage of using a hollow implant is the entrapment of the bone particles from the implantation site within the implant during impaction. 
         [0045]    An additional embodiment of the current invention is an anchor configured to provide for fixation of tissue directly to the bone adjacent to the anchor location.  FIG. 10A  shows the anchor in a constrained configuration for delivery. Active elements  1001  are constrained in this undeployed state in the distal end of the driver (not illustrated) while nosecone  1002  may be exposed beyond the distal end of the driver.  FIG. 10B  shows the same anchor after it has been placed in bony tissue and the anchor has been deployed from the delivery instrument so that it is unconstrained. Active elements  1001  include a plurality of fingers that are axially aligned with the longitudinal axis of the anchor when constrained, and expand radially outward when unconstrained. The elements spread out and allow for the capture of tissue between the fingers and the bone or other tissue into which the anchor is disposed. Nosecone  1002  is affixed into bony tissue. By varying different parameters of element  1001  which may include but are not limited to the thickness, material, heat treating, and radius of curvature of the deployed device, it will be possible to change the force of apposition between the two tissues to be fixed. This design also provides a degree of self-adjustment, allowing different tissue thicknesses to be attached to underlying bone by a single device without requiring a suture. By having a radius of curvature which changes along the length of the active elements  1001  rather than a constant radius of curvature, the device can be programmed to provide approximately the same force of apposition for a range of tissue thicknesses to the underlying bone with the same device design. This allows a surgeon to use a single cartridge-loaded device to place a number of anchors without device exchange. 
         [0046]    Element  1001  may be made from a resorbable material such as PLLA, collagen, highly crosslinked hyaluronic acid or the like. While some of these materials may be processed and formed to self-deploy as described above, many require secondary steps after placement to deform them into a fixation shape. As an example, when element  1001  is made from PLLA, a secondary step may include application of heat to element  1001  to plastically deform it into the desired final configuration. Once the heat source is removed, the PLLA or other plastically deformable material remains in its final shape and position. In other embodiments, the elements  1001  may be fabricated from self-expanding material like nitinol, spring temper metals, or resilient polymers. The elements may also be made from shape memory materials including metal alloys like nitinol or shape memory polymers. 
         [0047]    Additionally, elements  1001  and  1002  may be two separate elements, with element  1001  being placed on top of the tissue to be fixed, and  1002  being driven down through element  1001  and into the underlying bone, fixing element  1001  and tissue to be fixed. In this embodiment, element  1001  may be slotted as shown, or it may be configured more like a washer or grommet shape. 
         [0048]    In another embodiment both the portion of the anchor located in bony tissue and the anchor portion in the adjacent tissue may be configured with both elements being active. 
         [0049]    In yet another embodiment, an anchor  1102  may be constructed with a generally curved profile as shown in  FIG. 11A .  FIG. 11B  shows the anchor  1102  once it is loaded into a delivery system  1103  which constrains it to a generally straight profile within a constraining sleeve  1101  that is part of the driver. As the anchor  1102  is deployed from the constraining sleeve  1101  into the bone, it advances along a curved profile into the implantation site. 
         [0050]    The implants described in this invention could be made from metals like stainless steel, titanium, nitinol, etc., as well as resorbable and non-resorbable polymers like PLLA, PEEK etc. Implants may also be composites of two or more materials. 
         [0051]    The method, devices and implants described above could be used in a variety of applications including any application that requires an implant to be anchored into bony tissue. For example, placement of bone anchors in the humeral head for reattachment of a torn rotator cuff, placement of bone anchors in the acetabular or glenoid rim for reattachment of the torn labrum, placement of tacks to attach labral tissue to the glenoid rim, placement of screws in the vertebral bodies to attach cervical plates for spinal fusion, placement of screws in small joint bones for stabilizing reduced fractures, for treating stress urinary incontinence with a bone-anchored pubovaginal sling, placement of plates in cranio-facial reconstruction, fixation of fractures, etc. 
         [0052]    While the device and implants are designed to be used preferably in arthroscopic or minimally invasive procedures, they could also be utilized in open or mini-open surgical procedures. 
         [0053]    The implants in this invention may be loaded into a delivery device (e.g. a tube) which can be attached to the distal end of the impactor. The loaded delivery device may be designed to be introduced through a standard arthroscopic cannula and may contain one or more implants, thereby enabling the implantation of multiple implants without removing the delivery tool from the arthroscopic field. The delivery device may have features like a slit to enable manipulation of sutures attached to the implant. Alternatively, the sutures may pass through the body of the delivery device and be accessible through the proximal end of the cannula. 
       EXAMPLE 1 
       [0054]    An impactor device was fabricated similar to the device shown in  FIG. 4 . Air pressure was used to cycle a metal shuttle that impacts the active member at the distal end of the impactor. A cylindrical anchor (proximal diameter=1.5 mm, body diameter=2 mm) with a conical distal tip (length of anchor=6 mm), was loaded into the distal tip of the impactor. A #2 braided polyester suture was attached to the anchor via a hole through the minor diameter of the anchor. The distal tip of the active member had an OD of 2 mm and ID of 1.5 mm, and a slit to allow for egress of the suture. The impactor anchor assembly was connected to 90 psi compressed air. The distal end of the assembly was placed in contact with fresh cadaveric bovine cortical and cancellous bone. An air supply valve was opened and the anchors were driven into the bony tissue with ease. The pullout strength of the anchors were assessed subjectively and indicated good fixation of the anchors. The anchors were then carved out of the bony tissue and the surrounding tissue was examined for gross damage. There was no sign of thermal necrosis or other damage at the implantation site. 
         [0055]    While the above detailed description and figures are a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. The various features of the embodiments disclosed herein may be combined or substituted with one another. Therefore, the above description should not be taken as limiting in scope of the invention which is defined by the appended claims.