Abstract:
A method of anchoring soft tissue to a suitable bone site, using a soft suture anchor, includes steps of disposing the soft suture anchor on a shaft of an inserter, and securing a proximal end of a tensioning suture limb, extending proximally from the soft suture anchor, to structure in a handle of the inserter, so that it is maintained in place at a first level of holding tension (T hold ). The inserter shaft is inserted into a bone hole at a desired procedural site, so that the soft suture anchor is positioned at a location where it is to be anchored. A further step involves actuating a control mechanism in the inserter handle to move the structure proximally to apply a second level of deployment tension (T load ) to the tensioning suture limb.

Description:
[0001]    This application claims the benefit under 35 U.S.C. 119(e) of the filing date of Provisional U.S. Application Ser. No. 61/948,543, entitled All-Suture Anchor with inserter, filed on Mar. 5, 2014, and of the filing date of Provisional. U.S. Application Ser. No. 62/094,866, entitled All-Suture Anchor with Inserter, filed on Dec. 19, 2014. Both of these prior applications are herein expressly incorporated herein by reference, in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    There are many soft-tissue to bone repair procedures, such as rotator cuff, SLAP and Bankart lesion repairs, or reconstruction of labral tissue to the glenoid rim, in which a surgeon needs to secure tissue in close contact with bone by implanting an anchor, pre-loaded with suture, into a hole drilled in the bone at the desired anchor location. Commonly, the anchor which the sutures are attached to is made of either plastic such as PEEK or metal such as Titanium or Stainless Steel. Such anchors function like a nail or screw to secure them into the bone. Floating sutures, loaded into the rigid anchor body, are then passed through soft tissue near the anchor and the soft tissue is compressed against the bone surface by tying the suture ends into a knot. When the soft tissue is directly compressed against a bony surface, the body&#39;s healing response will affix the soft tissue to the bone to complete the repair. In the case of an implant pulling out of the bone there is a piece of hard material from that implant floating inside the joint space. That piece of material could temporary or permanently be stuck within the joint, causing damage to the articulating surfaces. 
         [0003]    Many surgeons are beginning to favor using all-suture suture anchors over traditional suture anchors. One particular advantage of using an all-suture anchor is that it requires a smaller hole to be drilled to the bone. Preserving bone is preferred by surgeons. There are quite a few all-suture anchor designs on the market today intended to capture this trend. 
         [0004]    The JuggerKnot™, by Biomet, has its anchor configuration made of a section of #5-polyester suture. The loaded suture is inserted through the length of the #5 suture section of the anchor. The anchor is preloaded on an inserter at the middle point. The inserter pushes the anchor into a drilled hole in the bone until a desired position is reached. The inserter is then removed. Both suture limbs are lightly pulled to contract the anchor, expanding it laterally against the wall of the drilled hole. This design relies on the friction between the suture ball of the anchor and the bone. Depending upon the position inside the hole to which the anchor is deployed or set, anchor slippage may occur when higher tension applied on the anchor until the anchor may move to a harder bone surface such as the cortex. 
         [0005]    ConMed Linvatec also has introduced an anchor called the Y-Knot™. The anchor is very much the same construct as the Biomet JuggerKnot anchor in terms of design, but with different suture material. It uses high-strength suture for the anchor instead of polyester suture. The technique for using the anchor is also very similar as the company suggests in its own words: “Drill Pilot Hole, Insert Anchor, and Pull-to set.” Since the anchor designs and techniques are similar, the anchor shares the same weakness of relying on friction. Thus, slippage can occur, and pull out strength could not be adequate. 
         [0006]    Another similar anchor is from Stryker and is called Iconix™. The anchor is designed to have opening sections along the sheet portion, which claim to provide a bunching effect using targeted compression zones. The middle point of the anchor is also preloaded on an inserter and inserted into a pre-drilled hole. When deployed by applying tension on the pre-loaded suture limbs, instead of the whole section of the anchor expanding randomly within the hole, those opening sections on the anchor are intended to swing outward laterally up to 3 mm-4 mm. However, such claimed expansion dimensions are theoretical only, because the soft suture is not stiff enough to penetrate the hole to achieve such dimensions in practice. 
         [0007]    All of the foregoing anchors are offered in different sizes (defined by the size of the hole drilled into the bone) and are pre-loaded with different sizes and numbers of floating sutures. All of these anchors, as noted above, are similar in construction: a floating suture or sutures are passed through a tube of larger suture. There may be one or more windows cut in the tube to allow the construct to bend at certain locations, as well as to allow the floating sutures to pass between the inside and outside of the tube. All of the anchors are then loaded onto similar inserters meant to push the anchor into a tunnel drilled into the bone. The anchors are wrapped around the top of the inserter shaft and secured in a fork at the tip. The floating sutures are routed along the inserter shaft and are secured in a cleat in the inserter handle. 
         [0008]    Advantages of all-suture anchors that have resulted in their increased popularity in orthopedic procedures include: 
         [0000]    a) the need for a smaller bone tunnel, because all-suture anchors deploy and change shape inside the bone tunnel, meaning that the drilled hole can be smaller than for rigid anchors with similar strength. This results in less bone removal and the ability to place anchors closer together when necessary;
 
b) ease of revision, because if an all-suture anchor does not deploy correctly, or if the surgeon is not comfortable with the bone quality after drilling the bone tunnel, the small hole allows the practitioner to drill a slightly larger hole in the same location and to use a traditional rigid anchor. If the anchor is deployed, it is easy for the surgeon to drill through or remove the anchor in order to implant another one; and
 
c) patient safety. In some cases, anchors can back out or be pulled out of the bone by patient activity or re-injury. If the anchor is located in a joint space, such as in the glenoid, and it pulls out of the bone after surgery, the soft material will not damage the bone surfaces (such as the humeral bead) as can be the case with a rigid anchor.
 
         [0009]    All of the foregoing anchors are also deployed in similar manners. Once the anchor is placed at the bottom of the bone tunnel, the floating sutures are removed from the inserter handle and the inserter is removed. To deploy the anchor, the physician is required to pull on the floating sutures. This tension applied to the floating sutures pulls the anchor upwardly in the bone tunnel, and the friction between the anchor and the bone causes the anchor to change shape and expand to create an interference fit in the tunnel. In addition, the larger diameter of the anchor prevents it from pulling up through the smaller hole in the harder cortical bone near the surface. The floating sutures are then passed through soft tissue and the remaining procedural steps are identical to those of any other pre-loaded suture anchor. 
         [0010]    Currently available all-suture anchors require manual tensioning by the practitioner in order to deploy the anchor, as noted above. Often, to avoid anchor pullout in soft bone, the practitioner will pull gently on one suture limb, then pull on the other, and back and forth in like manner until the anchor is deployed. The amount of tension required to fully deploy the anchor depends upon the bone quality, as well as practitioner skill, training, and experience. At a minimum, this results in inconsistent tension applied to deploy the anchor. This, in turn, will lead to inconsistent performance, both in cyclic displacement and ultimate pull-out strength. If the practitioner is concerned about the bone quality and only pulls gently to deploy the anchor (to avoid pulling the anchor out), the anchor displacement under cyclic loading will be greater and the ultimate pullout force could be reduced. Another failure mode is the anchor not expanding properly and pulling out of the bone tunnel during practitioner tensioning. This can happen if the bone is very hard and the anchor cannot properly expand, or if the bone is very soft and the practitioner pulls hard enough to overcome the maximum pullout force of the anchor. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention comprises an all-suture anchor together with an inserter and drill guide to deploy the anchor in bone. The inserter is designed to pull a specific and consistent range of tension each time in order to deploy the anchor in a bone tunnel. The drill guide provides a large footprint at the surface of the bone around the drill hole to protect the bone during anchor deployment. 
         [0012]    The amount of force applied to deploy the anchor is very important to its post-operative performance. For example, if the anchor is deployed by pulling at a particular level of tension on the sutures (40 N in one particular example), it will expand and move to a certain position in the bone tunnel. The sutures are then passed through soft tissue and tied down to secure the tissue against the bone. During post-operative activity and rehabilitation by the patient (prior to tissue healing), forces are exerted on the soft tissue and transferred through the suture to the anchor. If these forces are below the deployment tension level (40 N in our example), the anchor will remain in the same position. However, if the anchor is exposed to loads higher than the deployment force, it is likely to be pulled toward the surface of the bone. This movement can cause slack in the suture and allow a gap to form between the tissue and the bone, resulting in a failed repair. If the anchor is deployed at 100N during surgery, for example, it will remain stable at loads below this value. If it is pulled with too much force during deployment (more than its maximum pull-out force in that bone), it may pull out, especially if the bone is very soft or very hard. 
         [0013]    Bench testing, cadaver testing, and the literature review have been used to determine the appropriate minimum load the anchor should withstand post-operatively. Several cyclic loading studies by Barber et al. Specify cyclic loading from 0 to 60N to simulate forces applied to the suture anchors post-operatively, prior to tissue healing. Mazzocca et al. Deemed a peak cyclic load of 100N (for a 3-anchor construct sharing the load) to be appropriate for rotator cuff testing. The present invention is designed to deploy the anchor with a minimum, preferably, of approximately 60N of tension so that the anchor will not move when exposed to this load post-operatively. This is more tension that a physician can easily apply by hand, especially with only one floating suture loaded in the anchor. 
         [0014]    Bench and cadaver testing were performed to determine the upper range of the tension with which to deploy the anchor. Applying too much tension can cause the anchor to pull out of the bone, especially in very soft or very hard bone. In very to soft bone, excessive tension can cause the deployed anchor to pull upwardly through the soft bone. In very hard bone, the anchor cannot displace bone to fully expand to a larger diameter inside the tunnel. If it is deployed with more tension that the compression fit can withstand, the anchor will slide out of the hole. One particular embodiment of the present invention was tested in a range of bone block densities that simulate a range from very soft to very hard bone, as well as human cadaver bones. An upper limit of approximately 150N was found to be appropriate for proper deployment across the range of bone densities. 
         [0015]    The inventive inserter utilizes a knob to turn a screw to apply tension to the floating sutures. This design provides a mechanical advantage and allows the inserter to pull more tension to deploy the anchor than a surgeon can reliably pull by hand to achieve the desired range of deployment tension (60-150N). 
         [0016]    Another important component of the present inventive system is the drill guide. Most suture anchors on the market utilize a drill guide to help locate and maintain the position of the drill on the bone surface as well as to guide the anchor into the hole at the same angle as the drilled hole. For the described all-suture anchor of the present invention, the drill guide plays an integral role and is designed to aid in the anchor deployment. Since the inserter pulls on the anchor with a significant amount of tension, the opposing reaction force pulls the inserter against the bone surface. If the anchor were deployed without a drill guide, in soft bone, the deployment forces would pull the anchor upwardly toward the surface of the bone and simultaneously pull the inserter shaft downwardly into the bone, and full tension would not be reached. Most drill guides are made from thin-walled tubing to keep the outer diameter as small as possible. However, this thin, knife-kike edge at the tip can create a cylindrical cut into the bone around the tunnel if forced into the bone. This can also happen if the practitioner mallets too hard. on the inserter handle. If the inserter handle bottoms out on the drill guide, subsequent malleting will drive the inserter and drill guide into bone and damage the surface. The drill guide used with the described anchor and inserter has a much thicker wall section at the tip that provides a larger surface area to resist the downward forces (applied by the inserter during anchor deployment or by the practitioner during malleting). This downward pressure from the drill guide tip also protects the bone from damage or breaking as the anchor is pulled upwardly during deployment. If the anchor is manually deployed and the practitioner pulls very hard to deploy the anchor, it will expand and the force is then transmitted to the bone above it. If the bone is weak, it could break and leave a large crater on the surface of the bone. In the inventive system, the drill guide helps to prevent this mode of failure. 
         [0017]    Another improvement relates to the construction of the anchor itself. Many anchor designs were built and tested to determine the construction that could be inserted into the smallest diameter and shortest hole depth, and at the same time expand consistently to have the lowest cyclic displacement and highest pull-out force. 
         [0018]    More particularly, in one aspect of the invention, there is disclosed a soft suture anchoring system which comprises a suture anchor fabricated entirely of soft material, comprising a length of suture having a plurality of loops disposed therein and further comprising a tensioning suture limb disposed along the suture anchor and extending from one end of the suture anchor. An inserter is also provided for inserting the suture anchor into a bone hole, wherein the inserter comprises a shaft for holding and deploying the suture anchor and a handle proximal to the shaft. The handle comprises a structure attachable to the tensioning suture limb for holding and maintaining the tensioning limb under a first level of holding tension (T hold ) sufficient to hold the tensioning suture limb in place, and a tensioning mechanism which moves the structure proximally to apply a second level of deployment tension (T load ) to the tensioning limb to expand a lateral dimension of the suture anchor in order to deploy the anchor. 
         [0019]    In one disclosed embodiment of the invention, the structure comprises a crossbar. The crossbar is connected to the shaft, so that the crossbar moves axially when the shaft moves axially. The tensioning mechanism comprises a knob connected to a proximal end of the shaft, wherein rotation of the knob causes the shaft to move axially in a proximal direction. Specifically, in one approach, the proximal end of the shaft comprises external threads and the knob comprises internal threads which are engaged with the external threads, wherein rotation of the knob causes the shaft to be rotatably retracted proximally into the knob because of the threaded engagement of the knob and the shaft. 
         [0020]    A pinching mechanism is provided for pinching the tensioning suture limb against the crossbar. In one embodiment of the invention, the pinching mechanism comprises a pinching pin disposed adjacent to the crossbar. The pinching pin may be positionally fixed, or it may be axially movable to adjust T hold  and T load  to a desired level. In illustrated embodiments of the invention, T load  is 60N-150N. However, in certain cases, using the axially movable pinching pin, the desired level of T hold  and T load  is lower than 60N. 
         [0021]    In the disclosed invention embodiments, the shaft comprises an inner shaft, and the inserter further comprises an outer shaft surrounding the inner shaft. 
         [0022]    In another aspect of the invention, there is disclosed an inserter system for a soft suture anchoring system, wherein the inserter includes a shaft for holding and deploying a soft suture anchor and a handle proximal to the shaft. The handle comprises a structure attachable to the tensioning suture limb for holding and maintaining the tensioning limb under a first level of holding tension (T hold ) sufficient to hold the tensioning suture limb in place, and a tensioning mechanism which moves the structure proximally to apply a second level of deployment tension (T load ) to the tensioning limb to expand a lateral dimension of the suture anchor in order to deploy the anchor. 
         [0023]    In one disclosed embodiment of the invention, the structure comprises a crossbar. The crossbar is connected to the shaft, so that the crossbar moves axially when the shaft moves axially. The tensioning mechanism comprises a knob connected to a proximal end of the shaft, wherein rotation of the knob causes the shaft to move axially in a proximal direction. Specifically, in one approach, the proximal end of the shaft comprises external threads and the knob comprises internal threads which are engaged with the external threads, wherein rotation of the knob causes the shaft to be rotatably retracted proximally into the knob because of the threaded engagement of the knob and the shaft. 
         [0024]    A pinching mechanism is provided for pinching the tensioning suture limb against the crossbar. In one embodiment of the invention, the pinching mechanism comprises a pinching pin disposed adjacent to the crossbar. The pinching pin may be positionally fixed, or it may be axially movable to adjust T hold  and T load  to a desired level. In illustrated embodiments of the invention, T load  is 60N-150N. However, in certain cases, using the axially movable pinching pin, the desired level of T hold  and T load  is lower than 60N. 
         [0025]    In the disclosed invention embodiments, the shaft comprises an inner shaft, and the inserter further comprises an outer shaft surrounding the inner shaft. 
         [0026]    In yet another aspect of the invention, there is disclosed a method of anchoring soft tissue to a suitable bone site, using a soft suture anchor. The method comprises steps of disposing the soft suture anchor on a shaft of an inserter, and securing a proximal end of a tensioning suture limb extending proximally from the soft suture anchor to structure in a handle of the inserter, so that it is maintained in place at a first level of holding tension (T hold ). The inserter shaft is inserted into a bone hole at a desired procedural site, so that the soft suture anchor is positioned at a location where it is to be anchored. A further step involves actuating a control mechanism in the inserter handle to move the structure proximally to apply a second level of deployment tension (T load ) to the tensioning suture limb. 
         [0027]    The invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying illustrative drawing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIGS. 1-9  are views illustrating the construction of a suture anchor according to a first embodiment of the invention; 
           [0029]      FIGS. 10-18  are views illustration the construction of a suture anchor according to a second embodiment of the invention; 
           [0030]      FIG. 19  is an isometric view of a suture anchor insertion system including an inserter constructed in accordance with the principles of the invention; 
           [0031]      FIG. 20  is an isometric view of a distal end of the inserter of  FIG. 19 ; 
           [0032]      FIG. 21  is a schematic cross-sectional view showing the use of the inserter system of  FIGS. 19-20  and/or  FIGS. 28-29  to insert a suture anchor into a bone tunnel; 
           [0033]      FIG. 22  is a schematic top view of the handle portion of the inserter of  FIGS. 19-20  and/or  FIGS. 28-29 , illustrating its inner mechanical features; 
           [0034]      FIG. 23  is a schematic side view of the handle portion shown in  FIGS. 21-22 ; 
           [0035]      FIGS. 24-27  are views illustrating the construction of a suture anchor according to a third embodiment of the invention; and 
           [0036]      FIGS. 28 and 29  are schematic views illustrating an alternative embodiment of the inserter handle of the present invention, which is similar in all respects to the embodiment illustrated in  FIGS. 22-23  except for the addition of an ability to adjust tension control of the inserter system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0037]    Referring now more particularly to the drawings, there is shown in  FIG. 1  a suture anchor  10  comprised entirely of a suture material, as well as a floating suture  12 . It should be noted, at this juncture, that the invention comprises an inserter that applies tension to the floating sutures of an all-suture anchor in order to expand it within the bone tunnel to produce an interference fit of the anchor with the walls of the bone tunnel. The construction of the anchor itself also helps to provide a strong and secure anchor point in the bone. There are two particularly preferred methods of constructing the anchor  10  that result in a large change between the aspect ratio of the non-deployed anchor and the deployed anchor. It is desirable for the anchor  10  to be short and think for the insertion step of the procedure so that it can fit into a shallow, small diameter hole. This results in the least volume of bone removed from the patient. During deployment, the anchor  10  should expand as much as possible to provide compression against the walls of the bone tunnel, and to prevent it from pulling through the small diameter hole in the cortical bone at the tunnel entrance. 
         [0038]    Thus,  FIG. 1  illustrates a first embodiment of a suture anchor  10  constructed in accordance with the principles of the present invention. This embodiment is a single-loaded anchor.  FIG. 2  illustrates an assembly fixture  14 , wherein a piece of size 2 suture  16  (anchor suture) is wrapped around pins  18  of the fixture  14 , as shown. As shown in  FIG. 3 , a cap  20  is placed on the fixture  14  and a needle  22  with a snare loop  24  on one end is pierced through the anchor suture  16 . Then, the assembly  26  is removed from the fixture, as shown in  FIG. 4 . 
         [0039]    Referring to  FIG. 5 , one free end of the floating suture  12  is passed back and forth through loops  28  formed between the suture  16  and the needle  22  in the previous step. As shown in  FIGS. 6 and 7 , one end of the anchor suture  16  is placed in the snare loop  24  and pulled back through the suture strand. 
         [0040]      FIG. 8  illustrates a step wherein the floating suture  12  has been pulled tight, and the ends of the anchor suture have been cut off to complete the anchor construct  10 . 
         [0041]    Now with reference to  FIG. 9 , a second embodiment of a suture anchor  10  constructed in accordance with the present invention is illustrated. This embodiment is a double-loaded anchor. This embodiment  10  is constructed as shown in  FIGS. 10-18 .  FIG. 10  illustrates a first step in the method of constructing the double-loaded anchor  10  of  FIG. 9 , wherein a needle  22  with a snare loop  24  on the end is passed through the core of a size 2 piece of suture  16  (anchor suture). The step is repeated with a second needle  30  having a snare loop  32  being passed through a second piece of suture  16 , as shown. In  FIG. 11 , the long end of second anchor suture  16  is placed into the snare loop  24 . The needle  22  is pulled to pull the suture end through the core of the second anchor suture  16 .  FIG. 12  illustrates the result of this step. Then, the long end of the first anchor suture  16  is placed in the snare loop  32  and pulled through the core of the second anchor suture  16 .  FIG. 13  illustrates the resulting anchor loop  33 . 
         [0042]    As shown in  FIG. 14 , to load the floating sutures  12 , the loop  33  is placed over a suture snare  34 . The anchor loop  33  is twisted in alternating directions around the suture snare  34 , as shown in  FIG. 15 . Referring to  FIG. 16 , one free end of a floating suture  12  and two ends of the suture loop  33  are passed through the suture snare  34 . The suture snare  34  is then pulled to pull the floating suture  12  and suture loop  33  through the loops in the anchor. 
         [0043]    A second floating suture end is then passed through the suture loop  33 , as shown in  FIG. 17 . The loop is pulled in the opposite direction to pull the second floating suture through the loops in the anchor. 
         [0044]    As represented in  FIG. 18 , the anchor suture ends are then trimmed to length, completing the assembly of the second embodiment of the suture anchor  10 . 
         [0045]    The two suture anchor embodiments  10  disclosed herein result in anchors that can be placed into a shallow, small diameter hole, and then when deployed by the inserter can be deployed into a large ball which is securely anchored in the bone tunnel. 
         [0046]    Now with reference to  FIGS. 19-23 , the inserter  36  of the present invention will be described. The inserter  36  has two primary functions. A first function is to deliver the anchor  10  into the bone tunnel, and a second function is to apply tension on the floating sutures  12  to deploy the anchor  10 . One embodiment of the inserter  36  is illustrated in  FIG. 19 , comprising several components required to deploy the anchor. The following describes the anchor  10  loaded with one floating suture. 
         [0047]    Inside the inserter  36 , which comprises an inner shaft  38  housed within an outer shaft  39 , as well as a handle  44  disposed at a proximal end of the outer shaft  39 , the floating suture ends are wrapped around a crossbar  46  ( FIG. 22 ). Wrapping the suture around the crossbar  46  provides friction in order to tension the floating suture  12  and deploy the anchor  10 . After wrapping around the crossbar  46 , the suture ends pass through a hole in the crossbar  46  and are compressed between a pinching pin  48  ( FIG. 23 ) and an inner diameter of a hole in the crossbar  46 . Compressing the sutures between the crossbar hole and the pinching pin  48  provides the small holding tension required to keep the sutures from slipping around the crossbar  46 . The crossbar works like a capstan used in sailing. The tension to deploy the anchor (T load ) is counteracted by the sum of: 1) the friction of the suture wrapped around the crossbar, and 2) the friction of the suture compressed by the pinching pin  48  (T hold ). The relationship of these opposing forces is described by Eytelwein&#39;s formula: 
         [0000]      T load =T hold e φμ   
         [0000]    where
       Φ=total angle swept around the Crossbar   μ=coefficient of friction between the suture and the crossbar materials
 
The design of the illustrated embodiment results in a range of T hold  to achieve the desired deployment tension T load  (60-150N). The sutures are wrapped two times (Φ=720°=2π radians) around the crossbar and the coefficient of friction is determined by the suture and crossbar materials. The size and length of the pinching pin  48 , as well as the hole diameter in the crossbar  46  were chosen to achieve a specific range of holding tension, T hold . The suture is pinched enough so that the minimum T hold  is high enough to result in a minimum T load  of 60N and the maximum T hold  is low enough to result in a maximum T load  of 150N. The suture will begin to slip between the crossbar and the pinching pin when enough force is applied, keeping T load  below the desired value.
       
 
         [0050]    Clearly, there are other methods of pinching the suture to provide the holding tension T hold , such as spring clips, suture cleats, and the like. The suture ends are then wrapped inside the handle in such a way to allow them to unwrap and pay out of the inserter smoothly as it is removed after deployment. 
         [0051]    After the inserter tip and anchor are inserted into the bone tunnel, the anchor is deployed by turning a knob  50  on the proximal end of the inserter  36 . The knob  50  has an internal screw thread  51  that engages with an external thread  51   a  on the proximal end of the inner shaft  38 . When the knob is rotated, the inner shaft is moved proximally. The inner shaft  38  also has a cross pin  52  that prevents it from rotating within the inserter  36  and pulls the crossbar  46  along with the inner shaft  38 . For the first 9 mm of travel, the inner shaft  38  tip is pulling out of the bone tunnel and out from between the two sides of the folded-over anchor. This allows the anchor to move proximally during deployment and provides space in the bone tunnel for the anchor to deploy. After the inner shaft  38  moves 9 mm, the cross pin  52  contacts the crossbar  46  and begins to pull it proximally in conjunction with the inner shaft. This travel of the crossbar pulls tension on the floating sutures  12  which enlarges the anchor and causes it to compress inside the bone tunnel. The inner shaft, and crossbar travel for an additional 16 mm, which results in 60-150N of tension (T load ) in the floating sutures. 
         [0052]    When the inner shaft reaches 20 mm of travel, the pinching pin  48  in the crossbar  46  contacts a smaller diameter fixed pin  54  in the handle  44  ( FIG. 23 ). As it travels from 20 to 25 mm, the pinching pin  48  is pushed out of the crossbar to release the holding tension (T hold ) on the suture ends. When the holding tension drops to zero, the tension on the floating sutures in the anchor (T load ) drops to zero and the sutures can slide and unwrap easily from the crossbar. At this point, the inserter is pulled proximally from the insertion site and the sutures unwrap and pay out of the inserter handle and deployment tube  42 . 
         [0053]    As noted above, the second anchor configuration  10  is loaded with two floating sutures  12 . In this case, two suture ends are routed up the deployment tube  42 , with two limbs on either side of the inner shaft  38 . One set of floating suture ends  12  are wrapped around the crossbar  46  and then routed through the handle  44  without capturing the ends with the pinching pin  48 . The other set of floating sutures are wrapped around the crossbar  46 , captured by the pinching pin  48 , and then routed through the handle  44 , as described previously. This allows one floating suture  12  to provide the tension required to deploy the anchor and pulls the other floating suture  12  along with the anchor  10  as it deploys. This helps to ensure proper deployment and ensures that both floating sutures  12  can slide easily within the anchor after it is deployed. 
         [0054]    An additional feature is provided in the handle  44  to assist the practitioner. In the event that the floating suture  12  ends become tangled and caught in the handle during payout, suture access slots  56  ( FIG. 23 ) are provided in the handle  44  to allow the practitioner to cut the suture ends with a scalpel. This leaves enough length of floating suture  12  for the practitioner to complete the procedure. Reviewing  FIG. 23 , which is a depiction of the handle portion  44  of the inserter  36 , the handle top  44   a  and handle bottom  44   b  are illustrated for clarity. 
         [0055]    Another consideration for the design of the inserter shaft  39  is the ability to pass through a curved drill guide. In order to reach some locations (i.e. low on the glenoid rim), and to provide an angle as close to perpendicular to the surface as possible, a drill guide  58  ( FIG. 21 ) with an approximately 25 degree curve is used. The inserter shaft  39  is flexible enough to pass through this curved guide. 
         [0056]    The drill guide  58  is designed to work in conjunction with the inserter  36  to deploy the anchor  10 . The large surface area at the distal tip of the drill guide  58  lowers the pressure exerted on the bone surface  60  during anchor deployment ( FIG. 21 ). There are, in certain embodiments, two sizes of drill guides for the two anchor configurations, though, of course, the inventive system contemplates the usage of more than two different anchor configurations with a corresponding number of suitable drill guides. The single-loaded anchor drill guide, in one illustrative embodiment, has a tip surface area of 8.65 mm 2 , compared to approximately 4.25 mm 2  for a typical drill guide tip, an approximate 2:1 ratio. This reduces the pressure on the bone by about one half for the same applied force and greatly reduces the risk of the tip cutting into the bone during anchor deployment or practitioner over-malleting. It also provides an opposing force over a large surface area on the bone surface, above the deploying anchor, to prevent the anchor from pulling out of the bone during tension. 
         [0057]    Another alternative suture anchor embodiment  10  is illustrated in  FIGS. 24-27 . This anchor is constructed by wrapping anchor suture around a pin and tying two alternative half-hitches  62  ( FIG. 25 ). The two limbs are then wrapped around another pin, and more half-hitches  62  are tied. The center loop  64  is wrapped around a larger pin to allow for easier loading onto the inserter inner shaft  38 . The floating suture or sutures are then passed through the loops  66  (created by the pins) to complete the construct. 
         [0058]    This anchor is constructed by forming a double loop of suture, then wrapping one of the free ends around the loop approximately twenty times. The loop is then tightened around two posts a distance apart by pulling both free ends. This creates a loop, similar to the anchor loop of the previous double-loaded anchor embodiment  10  of  FIGS. 10-18 , The remaining construction steps are the same as previously described—the anchor is wrapped around a snare with alternating twists and a floating suture is pulled through the openings to complete the construct. 
         [0059]    In the foregoing described embodiments of the inserter  36 , the crossbar  46  travels a fixed distance before the sutures are released, resulting in a predetermined tension range to deploy the anchor  10 . If desired, however, this distance—and therefore, the deployment tension—can be adjusted by the practitioner. For example, the practitioner may be concerned about deploying in very soft or poor bone quality, and may want to deploy the anchor with a lower tension. The lower pullout force can be compensated for by implanting more anchors or further restricting the patient&#39;s post-operative activity. An embodiment of this modified design is illustrated in  FIGS. 28 and 29 . In this embodiment, adjustable deployment tension requires an adjustable tension control knob or switch  68  that the user can adjust as desired. In  FIG. 28 , the adjustable tension control  68  serves as a backstop and determines the position of the fixed pin  54 . In this first position, the fixed pin  54  is in a proximal position a distance x from the control  68 , which in one illustrative embodiment is approximately 12 mm, and contacts the pinching pin  48  when the crossbar  46  reaches 20 mm of travel. The pinching pin  48 , and thus the deployment tension (T load ) is released when the crossbar travels 25 mm, in the illustrated example. This is the high deployment tension position (the same as in the fixed embodiment described above). 
         [0060]    However, when the adjustable tension control  68  is actuated to its second position, as shown in  FIG. 29 , a ramp  70  pushes the fixed pin distally, so that the fixed pin is in a distal position a distance y from the tension adjustment control  68 . In the same illustrative embodiment, this distance y is approximately 14 mm. In this position, the pinching pin  48  contacts the fixed pin when the crossbar  46  reaches 18 mm of travel. The pinching pin, and thus, the deployment tension (T load ), is released when the crossbar  46  travels 23 mm. This reduced travel results in a lower maximum tension (T load ) applied to the floating sutures to deploy the to anchor. 
         [0061]    The tension adjustment control  68  may have two positions, as illustrated, comprising a “hard bone” position and a “soft bone” position, or it may alternatively be infinitely adjustable. The same function may be achieved with a slider or any other actuator which changes the position of the fixed pin with respect to the crossbar and the pinching pin. 
         [0062]    In the foregoing embodiments, the maximum tension applied by the inserter is limited by the fit of the fixed pin inside the crossbar. The floating sutures are pinched between these two components. When the tension becomes too high, the sutures will slip, placing a limit on the holding tension. T hold , and thus, on the deployment tension T load . If a more precise maximum deployment force were desired, the deployment tension applied to the floating sutures could be limited by utilizing a compression spring between the cross pin and the crossbar. In such a design, when the tension in the floating sutures exceeds the force exerted by the spring at the given length, proximal movement of the cross pin would simply compress the spring and not continue to move the crossbar proximally. Because the crossbar would not move, the only additional tension applied to the floating sutures would be through the spring. By choosing the proper spring parameters (length, spring rate) and distances between the cross pin and crossbar, a maximum force may be applied to the crossbar by the cross pin (through the spring), resulting in a maximum tension applied to the suture to deploy the anchor. 
         [0063]    In the described inserter embodiments, the suture is wrapped around a round crossbar in order to pull considerable tension on the floating sutures. There are other methods, however, which may be used to secure the floating sutures, including spring clips, suture cleats, and the like. A pinching pin is provided to secure the suture ends. This pin is released automatically when the inner shaft moves the designed distance. This pin may be replaced by a simple suture cleat on the crossbar and rely on the user to release the holding tension manually. This would require the suture ends to be accessible outside the handle. 
         [0064]    Accordingly, although exemplary embodiments of the invention has been shown and described, it is to be understood that all the terms used herein are descriptive rather than limiting, and that many changes, modifications, and substitutions may be made by one having ordinary skill in the art without departing from the spirit and scope of the invention.