Abstract:
A method of repairing a stifle, including a first stifle bone and a second stifle bone in engaged opposition to the first stifle bone. The method begins with screwing a first bone screw into the first stifle bone and screwing a second bone screw, having an aperture in its shank, into the second stifle bone. Next, a tension member is used to pull a suture loop, to engage a portion of the suture loop about the shank of the first bone screw. Then, the tension member is used to pull the suture loop through the aperture of the second bone screw and then into engagement about the shank of the second bone screw.

Description:
BACKGROUND 
     Currently, in the United States, many more cruciate ligament repair surgeries are performed on dogs than on people. Unfortunately, there is broad recognition that the available surgical procedures are sadly wanting in the degree to which the stifle (front knee joint of a dog) is repaired, and the durability of the repair. An improved technique and assembly for performing the technique is needed. 
     SUMMARY 
     The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements. 
     In a first separate aspect, the present invention may take the form of a repaired front stifle having a first stifle bone and a second stifle bone in opposed engagement to the first stifle bone, and having a first bone screw, having a head, and a shank fastened into the first stifle bone. A second bone screw having a head and a shank and having a through-hole in the shank, adjacent to the head, is fastened into the second stifle bone. Finally, a suture loop, is slidingly retained between the shaft of the first bone screw and the first stifle bone, and extends through the through-hole of the second bone screw and around the shank of the second bone screw. 
     In a second separate aspect, the present invention may take the form of a suture assembly that includes a suture loop, having a suture length comprised of woven material that is circular in cross-section, thereby defining a lumen. A tail of the suture length extends through the woven material to enter the lumen and is engaged within the lumen, thereby forming a loop. Further, a tension member is engaged to the suture loop. 
     In a third separate aspect, the present invention may take the form of a method of repairing a stifle, including a first stifle bone and a second stifle bone in engaged opposition to the first stifle bone. The method begins with screwing a first bone screw into the first stifle bone and screwing a second bone screw, having an aperture in its shank, into the second stifle bone. Next, a tension member is used to pull a suture loop, to engage a portion of the suture loop about the shank of the first bone screw. Then, the tension member is used to pull the suture loop through the aperture of the second bone screw and then into engagement about the shank of the second bone screw. 
     In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments are illustrated in referenced drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive. 
         FIG. 1  is a side view of a length of suture material, formed into a U, and to be used in a further part of the production of a suture assembly according to the present invention. 
         FIG. 2  is a side view of the material of  FIG. 10 , in a further step in the process of forming the length of suture material of  FIG. 10  into a portion of the suture assembly of the present invention. 
         FIG. 3  is an isometric view of a length of suture material and a lacing tool that is being used to form the suture material into a suture loop, which forms a portion of a suture assembly according to the present invention. 
         FIGS. 4-9  are isometric views of the elements of  FIG. 3 , in a series of further steps in the process of forming the suture assembly. 
         FIG. 10  is an isometric view of a final step in the production of one variant of a suture loop, which forms a part of a suture assembly according to the present invention. 
         FIG. 11  is an illustration of a stitching pattern used in part of suture assembly used in one embodiment of the present invention. 
         FIG. 12  is a side view of a length of suture material, formed into a U, and to be used in a further part of the production of a suture assembly according to the present invention. 
         FIG. 13  is a side view of the material of  FIG. 12 , in a further step in the process of forming the length of suture material of  FIG. 12  into a portion of the suture assembly of the present invention. 
         FIG. 14  is an isometric view showing a lancing tool arranging the suture of  FIG. 12 , so that it interlocks with the suture loop of  FIG. 11 . 
         FIG. 15  is an isometric view of a partially finished suture assembly, according to the present invention. 
         FIG. 16  is a side view of a finished suture assembly, according to the present invention. 
         FIG. 17  is a side view of two bone screws that are used in a method of repairing a cranial cruciate ligament, according to the present invention. 
         FIGS. 18A-18D  are successive steps in a cranial cruciate ligament repair surgery that utilizes the suture assembly of  FIG. 15 , and the screws of  FIG. 17 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Definitions 
     Bone screw: a screw having a head and an attached shank, and wherein the shank comes to a point at its end, to enable its introduction into bone. 
     Embodiments of the present invention are described below with reference to the above described figures. It is, however, expressly noted that the present invention is not limited to the embodiments depicted in the figures, but rather the intention is that modifications that are apparent to the person skilled in the art and equivalents thereof are also included. 
       FIG. 1  shows an open fiber  1  having two tails: a save tail  3  and a cut tail  2 . According to preferred embodiments, the fiber  1  is a biocompatible fiber, such as an ultra-high molecular weight polyethylene (UHMWPE) fiber, although suitable non-preferred materials can be used as well including polyester and POLYBLEND®, for example. Additionally, the fiber  1  is braided as opposed to being monofilamentous. Braided fibers are particularly advantageous in the teachings herein as they are stronger and define a lumen therein, which allows for the tails  3  and  2  to be threaded into the lumen as will be discussed in more detail below. 
     Referring to  FIG. 2 , an entry point  5  and an exit point  6  points can be designated along length of fiber  1  to define a middle section  9 . Save tail  3  includes all of fiber  1 , from exit point  6 , to the nearest end point, as shown. Table I can be utilized as an approximate guide to determine suitable lengths of the starting fiber  1 , save tail  3 , and middle section  9  based on the final loop size desired. For example if a 20 mm final loop size is desired, it would be advantageous to begin with a thread having a length of about 6 inches (152.4 mm), and to configure the thread such that the middle section is 35 mm in length and the save tail section is 40 mm in length. Loop size is measured from the largest inner diameter of the loop formed from fiber  1 , as described below. 
     
       
         
               
               
               
               
               
             
           
               
                 TABLE I 
               
               
                   
               
               
                 Loop 
                 Fiber 
                 Save Tail 
                 Middle Section 
                 Pre-Stretch 
               
               
                 Size 
                 Length 
                 Length 
                 Length 
                 Length 
               
               
                 (mm) 
                 (in) 
                 (mm) 
                 (mm) 
                 (mm) 
               
               
                   
               
             
             
               
                 15 
                 6 
                 40 
                 30 
                 ~13 
               
               
                 20 
                 6 
                 40 
                 35 
                 ~18 
               
               
                 25 
                 7 
                 40 
                 45 
                 ~23 
               
               
                 30 
                 8 
                 45 
                 60 
                 ~28 
               
               
                 35 
                 8 
                 50 
                 65 
                 ~33 
               
               
                 40 
                 10  
                 55 
                 75 
                 ~38 
               
               
                   
               
             
          
         
       
     
     As shown in  FIG. 2 , the fiber  1  is preferably fluffed at the entry  5  and exit  6  points to make it easier for a lacing tool  7  ( FIGS. 3-5 ) to be inserted through the middle section  9 . One end of the lacing tool  7  ( FIGS. 3-5 ) can include a handle to allow a user to position, guide, push, and pull the tool. The lacing tool  7  ( FIGS. 3-5 ) also includes a main body that is preferably substantially linear and having a diameter, or cross-section, small enough to thread through the fiber  1 . The end of the lacing tool  7  ( FIGS. 3-5 ) opposite of the handle can include a hinged barb  10  to allow for coupling to the fiber  1 . The hinge allows the barb  10  to have a lower profile when traversing through the inside of fiber  1  while minimizing the chance of snags. Other means for coupling to the fiber are readily contemplated and can non-exclusively include one or more barbs (hinged or unhinged) hooks, clamps (such that can be opened and closed by the handle) and the like, for example. Said means for coupling  10  preferably should not prevent or hinder the lacing tool  7  ( FIGS. 3-5 ) from being pushed into or pulled out of the inside of the fiber  1 . 
     As depicted in  FIGS. 3-5 , once the middle section  9  is defined, the barb  10  of the lacing tool  7  is pushed into the lumen of the fiber  1  at the fluffed entry point  5 . The barb  10  is pushed through the inside of the middle section  9  and guided outward through the fluffed exit point  6 . With reference to  FIGS. 4 and 5 , the cut tail  2  is then coupled to the barb  10  and configured to allow the lacing tool  7  and cut tail  2  to be pulled back into the middle section  9  at the exit point  6 . The barb  10  and coupled cut tail  2  are pulled out of the middle section  9  at the entry point  5 . As shown in  FIG. 6 , this step results in general loop shape with the cut tail section  2  being exposed out of the fiber  1  at the entry point  5 . The exposed cut tail  2  can be cut as close to the entry point  5  as possible, utilizing one or more of the following: scissors, knife, cutting instrument, thermal knife, and/or razor blade, and the like while avoiding cutting the external fiber near the entry point  5 . The remaining cut tail  2  can be retracted within the lumen of the fiber through the entry point  5 , as shown in  FIG. 7  by any suitable method, such as by manually or mechanically stretching the loop. One preferred method is to utilize needle holders to cinch the loop. For example, the closed jaws of needle holders or a scissor-like tool can be inserted into the loop then opened to stretch the loop. A preferred machine could be a force gauge. 
     Next, second entry  15  and exit  16  points ( FIG. 8 ) are defined along the fiber  1 . The second exit point  16  can preferably be positioned within close proximity to the end of the retracted cut tail  2  to minimize the amount of external fiber outside the loop lumen while still allowing for an internal overlap, or proximity, between the save tail and cut tail  2  and  3  within the lumen. These second entry  15  and exit  16  points can also be fluffed to allow for the lacing tool  7  to readily enter and exit the fiber  1 . After the second entry  15  and exit  16  points are defined, the barb  10  of the lacing tool  7  is pushed into the lumen of the fiber  1  at the fluffed second entry point  15 . The barb  10  is pushed through the inside of the fiber  1  and guided outward through the fluffed second exit point  16 . In one preferred embodiment, the assembly is essentially finished at this point, with the save tail being cut close to entry point  5 , to avoid having an unnecessary loose end. The reinforcing regions  20  and  21 , noted below and in  FIG. 10 , may then be applied, but simply to entry point  5  or to the location of cut end  2 . 
     The save tail  3  is then coupled to the barb  10  and configured to allow the lacing tool  7  and save tail  3  to be pulled back into fiber  1  at the second exit point  16 . The barb  10  and coupled save tail  3  can be pulled out of fiber&#39;s lumen at the second entry point  15 . As shown in  FIG. 9 , this step results with the save tail section  3  being exposed out of the fiber  1 . The exposed save tail  3  is preferably cut near the second entry point  15 , such that a small section of the save tail  3  is still exposed. Cutting can be done utilizing one or more of the following: scissors, knife, cutting instrument, thermal knife, and/or razor blade, and the like while avoiding cutting the external fiber near the second entry point  15 . 
     After the save tail  3  is initially cut, it is preferred to manually or mechanically expand the loop, thereby causing fiber  1  to contract in transverse dimension, so that it is in closer engagement with tails  2  and  3 . One preferred method is to utilize needle holders to cinch the loop. For example, the closed jaws of needle holders or a scissor-like tool can be inserted into the loop then opened to stretch the loop. A preferred machine could be a force gauge. The inner diameter of the loop can be measured to determine how close it is to the final desired size. If needed, the loop can be stretched using tools or machines prior to the stitching/securing steps described below. As a preferred example, the fiber loop can be manually or mechanically stretched to approximately 100 lbs. One type of suitable machine that can be used for this step is a force gauge. 
     In one preferred embodiment the stitching steps shown in  FIGS. 10 and 11  are not performed, with the natural engagement of the interior surface of fiber  1  with tails  2  and  3 , holding tails  2  and  3  in place. As shown in  FIG. 10 , a first stitching section  21  is defined by a section on the fiber  1  that encompasses the first exit point  6  where the cut tail  2  has entered into the lumen. As shown in  FIG. 10 , a second stitching section  20  is defined by a section on the fiber  1  that encompasses the ends of the cut tail  2  and the save tail  3 . It is important to note that the location of the first and second entry and exit points  5 ,  6 ,  15 , and  16  on the fiber  1  in  FIGS. 8-10  are non-limiting, as they can be positioned closer to each other or at different locations depending on the final size of the assembly. A needle  25  and thread  23 , such as UHMWPE thread, can be used to readily secure the first exit point  6  at the first stitching section  21  and the cut tail  2  and save tail  3  together at stitching section  20 . Additionally, other means for securing or reinforcing sections  20 ,  21 , besides stitching, can also readily be used. Non-exclusive examples, of securing or reinforcing means can include one or more adhesives, such as glue, heat setting, crimping. These means can be used by themselves or in conjunction with each other, or in conjunction with stitching. 
     After the first section  21 , having the first exit point  6  is stitched, or otherwise secured or reinforced, it is preferred to stitch or otherwise secure the second stitching section  20  where the cut tail  2  and save tail  3  overlap, or are otherwise in close proximity. According to one method, stitching using a needle  25  and thread  23 , such as an UHMWPE thread, can begin below the second entry point  15 , such that the stitching moves in an upwards direction towards the second entry point  15 . Alternatively, and as shown in  FIG. 10 , the stitching or reinforcing method can be started above the final section  20 .  FIG. 11  illustrates a preferred directional path of stitching along the fiber  1 . 
     If the stitching reaches a position adjacent and below or above the second entry point  15 , it is preferred to cut off the remaining exposed save tail  3  as close to the second entry point  15  as possible using any suitable cutting instrument, such as a razor blade, while not cutting, and thereby comprising the fiber  1 . Alternatively, this could be the first cut of the exposed save tail  3  as opposed to the second cut. The remaining save tail  3  can be retracted within the lumen of the fiber  1  through the second entry point  15  as shown in  FIG. 10 . The save tail  3  can be retracted into the fiber using any suitable method, such as by utilizing needle holders, as described above, or by other manual or mechanical methods of stretching the fiber loop. It is preferred that the save tail  3  is retracted within the lumen in close approximation, or on the same side of the loop, as the retracted cut tail  2 . More specifically, and as shown in  FIG. 10 , the save tail  3  and cut tail  2  are preferably aligned adjacent to each other to create an overlap of about ⅙-¼ of an inch depending on the final loop size desired (e.g., 15-60 mm). Additionally, the ends of the cut tail  2  and save tail  3  can be adjacent to each other, or alternatively there could be a small gap between the cut tail  2  and save tail  3 . 
     Once the save tail  3  is fully retracted within the lumen, and positioned overlapping or near the cut tail  2 , it is preferred to finalize the stitching in the second section  20 . Stitching, or otherwise securing, the cut tail  2  and save tail  3  together helps prevent fraying of the fiber  1 . As with the first section  21 , the second section  20  can be secured or reinforced utilizing other means besides thread and needles stitching. Non-exclusive examples, of securing means can include one or more adhesives, such as glue, heat setting or crimping. These means can be used by themselves or in conjunction with each other, or in conjunction with stitching. According to other embodiments, the save tail  3  can first be retracted within the lumen, and then stitching or securing of the second section  20  can begin. Stitching or securing of the second section  20  advantageously secures the cut tail  2  and save tail  3  together within the braid  1  and to the braided fiber  1 . 
     According to certain embodiments, the loop  22  can have only one stitched or reinforced section  20  or  21 , and no more. This single reinforced section can be the section shown in  21  that covers the first exit point  6 , where the cut tail  2  enters into the lumen of the fiber  1 . Under this embodiment, the ends of the cut tail  2  and save tail  3  would not be connected within the lumen of the fiber  1 . Alternatively, the single stitched or reinforced section can be the second section  20  that encompasses the cut tail  2  and save tail  3  junction within the lumen, without reinforcing the first exit point  6 . Additional embodiments include having one or more of the reinforced sections  20  and  21  to be doubly stitched. As noted previously, in a preferred embodiment, loop  22  has no reinforced section  20  or  21 , with the natural engagement of tails  2  and  3  within the lumen of suture material  1 , retaining tails  2  and  3 . 
     Alternative means of inserting the cut tail  2  and the save tail  3  into the lumen of the fiber  1  to achieve a similar final assembly are also readily contemplated herein. For example, a needle or other tool can be used to guide and insert the cut tail  2  and/or save tail  3  directly into the lumen of the fiber  1  without have the tool first being inserted into the lumen. According to alternative embodiments, the cut tail  2  and save tail  3  could be inserted within the lumen and left within, without having the ends first pulled out, cut, and retracted as described above. This could be done with the step of cinching/stretching out the loop, as described above. It is preferred that the cut tail  2  and save tail  3  are inserted substantially within the lumen, and not just their ends. More specifically, it is preferred that the entire circumference of the lumen, or substantially so, is occupied with either the cut tail  2  or save tail  3 , or both with respects to overlapping between the two. In a first preferred embodiment the suture loop  22  is made of USP-2 suture material and in a second preferred embodiment the suture loop is made of USP-5 material. 
     It is preferred that the assembly  22  is re-measured and re-stretched (e.g., at approximately 100 lbs.) if needed to achieve the final desired loop size. 
     Referring to  FIGS. 12-15 , after loop  22  is complete, construction of assembly  50  continues with a length of suture material  30 , in which an entry point  32  and an exit point  34  are defined and fluffed to facilitate entry and exit of lacing tool  7 . Next ( FIG. 14 ) suture  30  is extended through loop  22 , and lacing tool  7  is introduced into length  30  at entry point  32 , and out at exit point  34 , and captures a free end  36  of length  30 . Referring to  FIG. 15 , lacing tool is used to pull free end  36  through exit point  34  and entry point  32  to form a loop  38 , with a first portion  40  of length  30 , passing through a second portion  42  of length  30 . Assembly  50  is now essentially complete, with a further step in which stitching is used to fix portion  40  inside portion  42 , being performed in a preferred embodiment, and a loose end  44  being cut off. Referring to  FIG. 16 , at this point, assembly  50 , including loop  22  and eyelet-tail element  48  is complete. In an alternative preferred embodiment, eyelet-tail element  48  is replaced by another form of tension. In one embodiment wire is folded over a portion of loop  22  and used in the same manner as element  48 , in the method described below. In one embodiment this wire is made of nitinol. 
     Referring to  FIGS. 17 and 18A-18D , a veterinary surgery to implant loop  22 , so that it can absorb some of the stress normally born by the cranial (anterior) cruciate ligament is possible, using assembly  50 . A first bone screw  52  is introduced into the femur  54 , and a second bone screw  56 , having an aperture  57  in its shank, as shown is introduced into the tibia  58 . Eyelet-tail element  48  is used to pull loop  22  over the head of screw  52 , so that it is interposed between the head of screw  52  and femur  54 . Next, eyelet-tail element  48  is used to pull loop  22  through aperture  57 , then twist loop  22 , and extend a portion of it over the head of screw  56 , where it is interposed between this head and the tibia. Then screw  56  may be tightened to squeeze the interposed portion of loop  22  tightly between screw head and bone. Screw  52  may be tightened, but should be left loose enough so that loop  22  can slide about it. 
     While a number of exemplary aspects and embodiments have been discussed above, those possessed of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.