Abstract:
A system for repairing separated body tissues includes a tensioning device comprising two proximal handles for grasping, a pair of movable distal tensioning tips, a pivot between the proximal handle and distal tensioning tips, and suture holding clamps proximal to the tensioning tips. The tensioning device is used in conjunction with a buckle with lock bars and a tensioning tab for securing and tensioning suture. The tensioning tab is provided to secure the lock bar in its first position until tension on the suture exceeds a predetermined level.

Description:
This application claims the benefit under 35 U.S.C. 119(e) of the filing date of Provisional U.S. Application Ser. No. 61/982,265, entitled Tensioning Device for Dynamic Suture System, filed on Apr. 21, 2014, which application is expressly incorporated herein by reference, in its entirety. 
     Additionally, this application is related to U.S. Published Patent Application No. 2013/0184720, U.S. Pat. No. 8,414,599, U.S. Pat. No. 8,613,755, U.S. Pat. No. 8,303,591, U.S. Published Patent Application No. 2014/0018804, U.S. Pat. No. 8,579,901, U.S. Pat. No. 8,715,297, U.S. Pat. No. 8,668,696, and U.S. Published Patent App. No. 2011/0313435, all of which are commonly assigned and expressly incorporated herein, by reference, in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention is related to the general surgical repair of separated body tissues, and more particularly to internally fixating and stabilizing such body tissues, specifically bones. 
     In the present state of the art, there are a number of systems available to repair biological tissues separated in surgery or by injury. These products serve to approximate and stabilize the tissues so that healing may commence and provide compression in the interface to promote anatomical heal of tissue. With the correct amount of compression applied to the interface of the tissue portions to be joined, signals are sent to the tissue, thus allowing the tissue to remodel in proper anatomical position. The amount of compression applied to the tissue interface needs to be appropriate to the type of tissue that is being healed. 
     Twisted wires are typically used to keep bone fragments together so they may heal. Twisted wires only hold tension as long as the twisted wire pair remains stable. Often the wires untwist too soon, thus failing to keep the bone fragments together so that they may heal. Wires can also cut into bone fragments, allowing them to separate so that healing is difficult. 
     When it is necessary to access the thoracic cavity for a medical procedure, for example, it is required to cut the sternum into two pieces using a sternal saw. Once the procedure is completed within the thoracic cavity, the sternum must be repaired. For such repairs, it is known to use a dynamic compression device. Some of the drawbacks of this typical device, and others which are used include the fact that bulky spring materials used in such devices, while occupying substantial space, often do not store much energy. Some use polymer elastic bands, while others use coiled springs. Additionally, wires are sometimes used to wrap the bones into position in compression with one another. However, wires can have sharp ends that can damage adjunctive tissues. Knot stacks in suture can interfere with the natural movement of surrounding tissues. Another disadvantage of these prior art dynamic compression devices is that current banding systems that incorporate a biasing mechanism to achieve dynamic compression put the biasing mechanism in line with the band or suture. This practice competes with precious space at the healing site. Bands of suture are used to approximate tissues so that they may heal. It is desirable to obtain the best purchase possible on the tissue, so that the binding mechanics offered by the suture may be utilized. The best purchase is optimized by ensuring that the suture has the greatest contact area with the tissue. If a biasing mechanism is interfering with this concept, the biasing mechanism may diminish the suture&#39;s ability to hold the tissues together. 
     In addition, the current banding systems have stiff bands that are not compliant with bony undulations. Flat sutures are used, but are tedious to tie and do not hold reliably. 
     The banding systems of the present invention are therefore attractive for use in sternal closure because they offer some distinct advantage over twisted wires commonly used in the procedure. 
     Bands address the issues wires have, as noted in the following discussion. A band, by definition, is wide. In being wide, a band distributes its forces over a wider surface area. This inhibits the band from digging into the bone. In being wide, a band also affords a larger cross-sectional area, whereby more material may be realized, thus presenting the opportunity to offer as much strength in the construct as is necessary to hold the bone fragments together. As such, bands address two main weaknesses of twisted wires. These weaknesses are: digging into the bone fragments being held together, and not having sufficient cross sectional area. 
     However, with respect to bands, their strength is accompanied by stiffness, as mentioned elsewhere herein. The larger cross-section of the band significantly increases the stiffness of the band. While stiffness and rigidity are good attributes in the sense that they can stabilize the bone union, these attributes can also prevent the band from following the contours of the bone when inserted. This can lead to capturing tissues underneath the band that ultimately destabilize the union as the tissues continue and disappear over time. 
     Binding the band ends together can also impose some problems. Generally this binding involves a mechanism on the band end that interfaces with holes or slots or contours on the other band end. This creates a tensioning system that is incremental in nature. As in the twisted wire systems, this mechanical interface of the two ends id the weakest link in the banding system. This mechanical interface becomes conductive to fine tuning the tension, so this is problematic. Flat sutures have been used to tie tissues together, but the residual tension supplied in such a knotted structure is insufficient for optimum healing. There is a lot of fuss and time associated with trying to keep and hold a desirable tension with these sutures. What is needed is an attachment means that provides variable tensioning. 
     Another problem associated with banding systems is that their tension holding capabilities are not sufficient for the environment in which they operate. Tension holding ability can be increased or enhanced by increasing friction at the binding interface of the band. What is needed however is a banding system with the ability to hold tension by selectively increasing friction at the binding interface during locking and/or after locking without increasing friction while tensioning. 
     What is needed, therefore, are improved devices and techniques for holding two tissue portions in a state of compression and tension that address and overcome these shortcomings in an innovative way. 
     SUMMARY OF THE INVENTION 
     The present invention solves the problems outlined above by providing a mechanized tensioning system for consistently and evenly applying a prescribed predetermined level of tension to the suture, at which point the suture is clamped in place with a buckle. 
     More particularly, there is provided a tensioning device comprising two proximal handles for grasping, a pair of movable distal tensioning tips, a pivot between the proximal handle and distal tensioning tips, and suture holding clamps proximal to the tensioning tips. 
     The tensioning device is used in conjunction with a buckle that includes a lock bar and tensioning tab for securing and tensioning suture, the tension tab is provided to secure the lock bar in its first position until tension on the suture exceeds a predetermined level. 
     In one particular aspect of the invention, there is provided a tensioning device for tensioning suture bands having free ends fastenable using a buckle, which comprise a pair of proximal handles for grasping and applying tension, a pair of movable tensioning tips disposed distally to the handles, a spring disposed between the handles for biasing the handles to a desired state, a pivot joining the handles and the tensioning tips so that they are pivotally connected, and suture holding clamps disposed between the tensioning tips and the handles. The combination may also comprise suture guides on a proximal end of each handle for holding and managing excess suture length. The handles for grasping and applying tension are shaped in such a way as to provide mechanical advantage for various hand sizes and holes for lighting device, which also aid in the use of suture clamps. The movable tensioning tips are smooth and round to provide free movement of the band and also include raised sides to prevent band slippage. The spring may preferably comprise a leaf spring and is positioned between the handles with screws in such a way as to provide easy access for cleaning and sufficient force to return handle to original state. 
     The pivot is positioned in such a way as to provide a desired amount of leverage and travel of the movable tensioning tips, when the handle is squeezed to cause the tensioning tips to move outwardly. The suture holding clamps are disposed between the tensioning tips and the handles and comprise a holder and a toggle clamp. The toggle clamp includes a cam with serrations for gripping suture band and a handle with sufficient length to provide leverage for clamping. 
     The holder includes a smooth surface for the toggle clamp to rotate on, a feature to stop toggle rotation, and a threaded feature for securing a precision shoulder screw. The suture guides on the proximal ends of the handles comprise narrow slots with chamfer lead in features to assist in positioning the bands within the narrow slots. The suture holding clamps disposed between the tensioning tips and handles comprise narrow suture holder slots, thumbscrews for clamping, and suture guide pins. 
     The suture holding clamps disposed between the tensioning tips and handles may comprise suture holder slots, thumbscrews, movable jaws for clamping, and suture guide pins, or may alternatively comprise toggle clamps with dual support toggle clamp holder, and suture guide pins. In yet another embodiment, the suture holding clamps comprise toggle clamps with toggle clamp holder, and suture guide pins. 
     The tensioning tips comprise pivots, and tensioning leaf springs to control the amount of tension the tensioning device can deliver. 
     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 drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front isometric view of one embodiment of a tensioning device constructed in accordance with the principles of the present invention, including an illustration of a buckle and a band on the sternum; 
         FIG. 2  is a front isometric view of the distal end of the tensioning device of  FIG. 1 ; 
         FIG. 3  is a front isometric view of the tensioning device of  FIGS. 1 and 2  shown in the closed position; 
         FIG. 4  is a front isometric view of the distal end of tensioning device of  FIGS. 1-3  in the closed position; 
         FIG. 5  is a rear isometric view of the tensioning device of  FIGS. 1-4  in the closed position; 
         FIG. 6  is a front isometric view of the tensioning device of  FIGS. 1-5  in the open position; 
         FIG. 7  is a front isometric view of the distal end of the tensioning device of  FIGS. 1-6  in the open position; 
         FIG. 8  is a front isometric view of a modified embodiment of the tensioning device of the present invention, using alternate suture holding clamps with thumbscrew, suture guides, and suture guide pins; 
         FIG. 9  is a front isometric view of the tensioning device of  FIG. 8 ; 
         FIG. 10  is a front isometric view of another modified embodiment of the tensioning device of the present invention, using alternate suture holding clamps with toggle clamps, dual support toggle clamp holder, and suture guide pins; 
         FIG. 11  is a front isometric view of still another modified embodiment of the tensioning device of the present invention, using alternate suture holding clamps with toggle clamps, toggle clamp holder, and suture guide pins. 
         FIG. 12  is a front isometric view of yet another modified embodiment of the tensioning device of the present invention, with pivoting tensioning tips and springs for force control, shown with buckle, band, and no tensioning tab; 
         FIG. 13  is a front isometric view of the distal end of the tensioning device of  FIG. 12 ; 
         FIG. 14  is a front isometric view of still another modified embodiment of the tensioning device of the present invention, with pivoting tensioning tips and springs for force control; 
         FIG. 15  is a front isometric view of the distal end of the tensioning device of  FIG. 14 , with pivoting tensioning tips and springs for force control, distal end; 
         FIG. 16  is a front isometric view of yet another embodiment of the tensioning device of the present invention; and 
         FIG. 17  is a front isometric view of the distal end of the tensioning device of  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring more particularly to the drawings, there is shown in  FIGS. 1-7  a first embodiment of a tensioning system  10  constructed in accordance with the principles of the present invention. The system or device  10  comprises two proximal handles  12 , for grasping and applying tension, a pair of movable distal tensioning tips  14  disposed distally to the handles, and a leaf spring  16  disposed between the handles  12  which are biased for returning the handles to their original state. The handles  12  and tensioning tips  14  are pivotally joined together by a pivot pin  18 . Suture holding clamps  20  are disposed on the device  10  between the handle portions  12  and the tensioning tips  14 , proximal to the tensioning tips, as shown. Suture guides  22  are disposed on the proximal end of handles  12  for holding and managing excess suture length (suture  23 ). The pivot  18  is positioned in such a way as to provide the right amount of leverage and travel of the movable tension tips  14 . When the handles  12  are squeezed, the tensioning tips  14  move outwardly. 
     Advantageously, the handles  12  are shaped in such a way as to provide mechanical advantage for various hand sizes and include apertures for accommodating a lighting device, which also aid in the use of the suture clamps. 
     The movable tensioning tips  14 , as illustrated, are round and smooth, for providing free movement of the band. This is best shown in  FIGS. 2 and 7 . The tips  14  comprise a recessed center portion  24  for accommodating the band, and raised side walls  26  defining the recessed center portion  24  for preventing band slippage. 
     The leaf spring  16  is positioned between the handles  12 , as shown in the drawings, using screws  28 , or other suitable fasteners, in order to provide easy access for cleaning and sufficient force to return the handle to its original state. 
     In the  FIGS. 1-7  embodiment, the suture holding clamps  20  include a proximal thumb flange or actuator  30  for pivoting the clamp  20  between open and clamping positions about pivot screws  32 . 
       FIGS. 8 and 9  illustrate a modified embodiment of the invention, wherein like elements are identified by like reference numerals to those used in  FIGS. 1-7 . In this embodiment, however, the suture holding clamp  20  comprises a thumbscrew  34 , suture guides  36 , and suture guide pins  38 . 
     In  FIGS. 10 and 11 , two additional modified embodiments are illustrated, wherein, once again, like elements are identified by like reference numerals to those used in  FIGS. 1-9 . In  FIG. 10 , the suture holding clamps  20  have been modified, so that they comprise suture guide pins  38 , and the clamp  20  comprises a toggle clamp including a toggle actuator  40  for selectively clamping suture within a suture clamping channel  42 .  FIG. 11  is similar, but includes different constructional details for the suture holding clamps. 
       FIG. 12  illustrates yet another modified embodiment of the inventive device  10 , wherein, again, like elements are identified by like reference numerals. In this embodiment, a second spring  42  is disposed between the tensioning tips  14  in order to provide force control for the tensioning system.  FIG. 13  is an enlarged view of the distal end of  FIG. 12 .  FIGS. 14 and 15  illustrate the  FIG. 12-13  embodiment without the sternum and suture buckling system in place. 
       FIGS. 16 and 17  illustrate still another modified embodiment of the present inventive device  10 . In this embodiment, as in the  FIGS. 1-2 and 12-13  embodiments, the embodiment is shown in conjunction with the application for which it has been particularly adapted. That application is in connection with a sternal bone  44  which has been separated for the purpose of performing a surgical procedure, and is now being joined together using a suture band  46 , wherein the band is to remain in place about the bone until natural healing takes place. A buckle  48  is utilized to join the free suture ends together, and to adjust the tension on those suture ends. A buckle system of the type shown herein is shown and disclosed in much greater detail in commonly assigned U.S. Published Patent App. No. 2013/0184720, which has already been expressly incorporated herein by reference, in its entirety. 
     Thus, in practice, the suture band  46  is positioned as desired around the bone  44  to be repaired, and is then tensioned to tighten the band around the bone in order to secure the bone in proper position, and to ensure that the band will remain in tension during the entire healing process, by ensuring that the implant follows the bone as it shrinks during healing. During this tensioning step, a lock bar (not shown) in the buckle remains in an unactuated position, permitting free movement of the suture band  46  through the gap in the buckle  48  as the tensioning proceeds. When a predetermined tensioning force is applied to the suture band  46 , the friction forces restraining the lock bar are overcome, and the lock bar breaks free from its restraint, moving to a locking position. This locks the buckle in place, preventing further movement of the suture band  46 . 
     In practice, it is difficult to manage the required amount of force to clamp the suture in place using manual techniques. Thus, the tensioning system shown and described herein assists in applying a consistent and required tension level. As shown, the band  46  passes around each tensioning tip  14 , as shown. To retain the suture band in place, it is seated in the tensioning tip recessed center portion  24 , between raised side walls  26 . The suture bands  46  then extend through the suture holding clamps  20  and along the handles  12  exit the tensioning device through suture guides  22  as suture free ends  23 . No threading is necessary. The closed position of the tensioning device  10  occurs when the handles  12  are spaced apart, and the movable tensioning tips are in close proximity ( FIGS. 1-5 , for example). The open position is shown in  6 - 9 , for example. 
     When it is desired to apply a tensioning force to the two suture band ends disposed about each of the tensioning tips  14  and over the device  10 , the suture holding clamps  20  are actuated to clamp the suture band  46  in place on either side of the device, and the handles are squeezed together to move the device to its open position, with the tensioning tips in their spaced apart orientation. This movement causes tension to be applied to the suture band  46  in the vicinity of the buckle  48 . When the suture is tensioned as desired, the buckle is fastened, after which the suture holding clamps  20  can be released, and the handles  12  permitted, by action of the leaf spring  16 , to return the tensioner to its relaxed closed position. Then, the suture ends may be trimmed, as desired. 
     Accordingly, although exemplary embodiments of the invention have 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, which is to be limited only in accordance with the following claims.