Abstract:
A catheter device that includes a double-threaded guidance wire that allows multiple use of a compliant cavity creation device (i.e., treatment of more than one level). The double-threaded guidance wire may be connected with the luer part of the device and a distal part of the balloon using a threaded engagement to avoid lengthening of the inner tube, avoid lengthening of the balloon, and to limit the plastic deformation of the system in axial direction. In other implementations, the double-threaded guidance wire may be reconnected to the distal part of the balloon with a distal thread of the double-threaded guidance wire in order to restore the nominal length.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/904,975 filed on Oct. 14, 2010, entitled: “DOUBLE THREADED GUIDANCE OR STIFFENING WIRE FOR MULTIPLE USE VERTEBRAL AUGMENTATION (VA) BALLOON,” which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    Osteoporosis is a disease that gradually weakens bones and causes them to become brittle. Left untreated, osteoporosis can progress painlessly until a bone breaks. In some cases, osteoporosis can cause compression fractures in the spine. This occurs when the bony block, or vertebral body, in the spine collapses. This causes severe pain, deformity, and loss of height. It can also lead to nerve compression. 
         [0003]    Until recently, doctors were limited in how they could treat osteoporosis-related spine fractures. For example, typical options included pain medications, bed rest, bracing or invasive spinal surgery. More recently, the vertebroplasty and kyphoplasty procedures have become available as therapeutic and preventive treatments for compression fractures. Vertebroplasty involves passing a bone needle slowly through the soft tissues of the back to deposit a small amount of orthopedic cement, called polymethylmethacrylate (PMMA) into the vertebral body. PMMA is a medical grade bone cement that has been used for many years in a variety of orthopaedic procedures. 
         [0004]    Kyphoplasty is a procedure that involves making small incisions and placing a catheter into the vertebral space where the fracture is located. A cavity is created inside the bone (e.g. drilled) and a balloon, called a bone tamp, is inserted. The balloon may be support by a guidance wire that is passed through a central lumen of the catheter. The balloon is then inflated with contrast medium until it expands to a desired height, deflated and removed. The balloon is used to expand and reposition the compressed bone, and to create a cavity for cement. The cavity created by the balloon may then be filled with PMMA, binding the fracture. Kyphoplasty substantially restores height to the spine, thus reducing deformity (also pain relief). 
         [0005]    However, the majority of the balloons utilized by kyphoplasty catheters are made of a ductile (compliant) material. Ductile materials initially undergo elastic (reversible) deformation, followed by plastic (permanent) deformation after reaching a yield point. Therefore, when the balloon is inflated in bone to reduce a fracture, it undergoes some permanent deformation (e.g., deformation of the inner tube and deformation of the balloon). As such, reinflation of the balloon will be biased. Reinserting the guidance wire would result in a non-supported distal balloon part because of the lengthening of the balloon that results from plastic deformation. Therefore, the balloon should not be reused. 
       SUMMARY 
       [0006]    Described herein is a tool that enables multiple use (i.e., reuse) of a catheter for example in a multi-level vertebral augmentation procedure. As described below, the tool may include a balloon catheter that may be a two (or more) lumen catheter. An outer lumen may be used for inflation of the balloon and an inside lumen for guiding a double-threaded guidance wire. A thread in the distal part of the guidance wire may be provided with outer diameter of the distal thread being less than the inner diameter of an inner tube of the catheter. The construction of the thread (i.e., outer diameter, inner diameter, flank lead, length) can be standard design (ISO, Metric) or any design allowing a locking mechanism. The counter piece (e.g., a distal threaded nut) for the distal thread of the guidance wire may be disposed inside the balloon of the catheter and connected to the inner tube. This nut can also be used as a radiopaque marker inside the balloon. 
         [0007]    The guidance wire may also have a proximal thread with an outer diameter greater than an outer diameter distal thread. The construction of the thread (e.g., outer diameter, inner diameter, flank lead, length) can be standard design (ISO, Metric) or any design allowing a locking mechanism. The counter piece (e.g., a proximal threaded nut) for the proximal thread of the guidance wire may be disposed inside a luer connector (e.g., a connector for balloon inflation) of the catheter and positioned coaxial to the inner tube. The length of the proximal threaded nut may be longer than the distal threaded nut to account for changes of the balloon catheter during inflation. 
         [0008]    In one implementation, the double-threaded guidance wire may remain connected to the balloon during inflation to prevent the balloon and the inner tube from lengthening, substantially avoiding plastic deformation in an axial direction. In another implementation, the double-threaded guidance wire may be removed from the tool during balloon inflation. Thereafter, the double-threaded guidance wire can be reinserted into the tool to connect to the thread in the balloon to restore the pre-inflation nominal balloon axial length and stiffness before inflation. Thus, after first use of the tool, it can be reinserted and used again, as the same catheter length and balloon length is preserved with only minor plastic deformation in axial direction. 
         [0009]    In some implementations, there is provided a reusable tool that includes a handle having a proximal thread. A catheter structure may be included that has an outer body and an inner body. The outer body may be connected to a fitting of the handle. An expandable structure may be connected to the outer body, where the expandable structure has a distal thread affixed within an interior thereof. A guidance wire maybe disposed within the inner body, where the guidance wire has a first threaded portion adapted to engage the proximal thread and a second threaded portion adapted to engage the distal thread. 
         [0010]    In other implementations, there is provided a reusable tool for treating a vertebral body. The tool may include a handle having an inflation port and a proximal thread. A dual-lumen catheter may be connected to a fitting of the handle and a balloon connected to the outer body. The balloon may have a distal thread affixed within an interior thereof. A guidance wire may be disposed within an inner lumen of the dual-lumen catheter, where the guidance wire has a first threaded portion adapted to engage the proximal thread in the handle and a second threaded portion adapted to engage the distal thread in the balloon. 
         [0011]    In yet other implementations, there is provided a tool for treating a vertebral body that includes a handle having an inflation port, a luer fitting and a proximal thread disposed with a body of the handle. A catheter body may be attached to the luer fitting of the handle. A balloon may be connected to the catheter body, where the balloon has a distal thread affixed within an interior thereof. The tool may further include a dual-threaded guidance wire having a first threaded portion adapted to engage the proximal thread and a second threaded portion adapted to engage the distal thread. 
         [0012]    In accordance with further implementations there is provided a method for treating bone with a tool having a catheter tube assembly. The method may include fixing a double-threaded guidance wire to a distal threaded nut of an inflatable structure, and deploying the inflatable structure inside a first location of the bone. The inflatable structure may be inflated to create a cavity within a treatment area of the bone, after which the inflatable structure is deflated and removed from inside the bone. The inflatable structure may then be reused and reinserted within the treatment area or inside a second location of the bone. 
         [0013]    This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended that this summary be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    To facilitate an understanding of and for the purpose of illustrating the present disclosure, exemplary features and implementations are disclosed in the accompanying drawings, it being understood, however, that the present disclosure is not limited to the precise arrangements and instrumentalities shown, and wherein similar reference characters denote similar elements throughout the several views, and wherein: 
           [0015]      FIG. 1  is a view of a reusable tool having an balloon structure; 
           [0016]      FIG. 2  is a cross-sectional view of a catheter tube assembly of the reusable tool of  FIG. 1 ; 
           [0017]      FIG. 3  is a view of the reusable tool of  FIG. 1  showing additional details of a double-threaded guidance wire; 
           [0018]      FIG. 4  is a cross-sectional view of a proximal threaded nut; 
           [0019]      FIG. 5  is a cross-sectional view of a distal threaded nut; 
           [0020]      FIG. 6  is a cross-sectional view of the double-threaded guidance wire; 
           [0021]      FIG. 7  illustrates an implementation to inflate the balloon structure with the double-threaded guidance wire attached thereto; 
           [0022]      FIG. 8  is operational flow diagram of exemplary processes that are performed as part of a procedure using the implementation of  FIG. 7 ; 
           [0023]      FIG. 9  illustrates an implementation to inflate the balloon structure where the double-threaded guidance wire is removed during inflation of the balloon structure and reinserted to withdraw the balloon structure; and 
           [0024]      FIG. 10  operational flow diagram of exemplary processes that are performed as part of a procedure using the implementation of  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Referring now to  FIGS. 1-6 , there is illustrated aspects of a reusable tool  100  that includes a double-threaded guidance or stiffening wire  112 . The tool  100  includes a catheter tube assembly  104  made from, e.g., metal or extruded plastic materials. In some implementations, the catheter tube may be generally flexible. The distal end of the catheter tube assembly  104  carries a balloon structure  106 , which is made, e.g., from a deformable plastic or other compliant material. In use, the balloon structure  106  is deployed and expanded inside bone, e.g., in a vertebral body, to compact cancellous bone and/or displace cortical bone. 
         [0026]    As best shown in  FIGS. 1 and 2 , the catheter tube assembly  104  includes an outer catheter body  108  and an inner catheter body  110 . The inner catheter body  110  extends through and beyond the outer catheter body  108  into the balloon structure  106 . The proximal ends of the inner catheter body  110  and the outer catheter body  108  are jointly coupled to the distal end of a luer fitting  114  on a y-shaped luer connector  102 , which serves as a handle for the tool  100 . 
         [0027]    As shown in  FIG. 1 , the proximal end of the inner catheter body  110  extends within the luer connector  102  beyond the coupled proximal ends of the outer catheter body  108 . The extended proximal end of the inner catheter body  110  is coupled to the luer connector  102  at a location proximal to an inflation port  120 . The distal end of the inner catheter body  110  extends beyond the distal end of the outer catheter body  108 . 
         [0028]    The balloon structure  106  is coupled at its proximal end to the distal end of the outer catheter body  108 . The balloon structure  106  is coupled at its distal end to the double-threaded guidance wire  112  that extends beyond the distal end of the inner catheter body  110 . The double-threaded guidance wire  112  is coupled at its proximal end to a rotatable luer cap  116 . 
         [0029]    As shown in  FIG. 2 , the interior diameter of the outer catheter body  108  is larger than the exterior diameter of the inner catheter body  110 . An interior passage  122  is thereby defined between them. In use, the interior passage  122  conveys a pressurized flowable medium, e.g., sterile water, radiopaque fluid, gas, or other flowable substance into the balloon structure  106 , to expand it. The inflation port  120  on the luer connector  102  (see, e.g.,  FIG. 1 ) serves, in use, to couple the interior passage  122  to the source of pressurized flowable medium (not shown). The inner catheter body  110  defines an interior lumen  124  within the interior passage  122 . The double-threaded guidance wire  112  extends through the interior lumen  124 . 
         [0030]    With reference to  FIGS. 1 and 3 , the luer cap  116  rotates about a proximal luer fitting  118  on the luer connector  102 . Twisting the luer cap  116  rotates the double-threaded guidance wire  112  within the inner catheter body  110 . The torque caused by twisting the luer cap  116  is transmitted to a first threaded portion  126  of the double-threaded guidance wire  112  that engages a proximal threaded nut  128  within the luer connector  102  (see, reference A). The proximal threaded nut  128  may be conical in shape to remain fixed against a pull force of the guidance wire  122  (described below), thus providing a form closure inside the luer connector  102 . The proximal threaded nut  128  may also be attached to the luer connector  102  by, e.g., glue, threads, a pin, etc., such that it remains secure. 
         [0031]    The torque is also transmitted to a second threaded portion  132  of the double-threaded guidance wire  112  that engages a distal threaded nut  130  within the balloon structure  106  (see, reference B). The distal threaded nut  130  may be used as a radiopaque marker inside the balloon structure  106 . A marker  134  may be provided that is fixed to a portion of the inner catheter body  110  that extends within the balloon structure  106 . The marker  134  may be a radiopaque marker viewed using plain film x-ray, fluoroscopic x-ray, MRI or CT scanning. 
         [0032]    The threads of the nuts  128  and  130 , and the guidance wire  112  can be designed both with a left-hand thread or both with a right-hand thread. The threads can also be designed in opposite direction (one left-hand thread and the other right-hand thread). The interaction of the double-threaded guidance wire  112 , proximal threaded nut  128 , distal threaded nut  130  and the balloon structure  106  is described below with reference to  FIGS. 7-10 . 
         [0033]    In some implementations, as shown in  FIG. 4 , the proximal threaded nut  128  may have a length of 15-40 mm. The diameter of the hole of the proximal threaded nut  128  may be approximately 1.6 mm. As shown in  FIGS. 3 and 5 , the distal threaded nut  130  may be inside the balloon structure  106  and have a length of 2-3 mm. The diameter of the hole of the distal threaded nut  130  may be approximately 1.0 mm. 
         [0034]    The material from which the balloon structure  106  is made may possess various physical and mechanical properties to optimize its functional capabilities to compact cancellous bone. Such properties may include the ability to expand in volume, the ability to deform in a desired way when expanding and assume a desired shape inside bone, and/or the ability to withstand abrasion, tearing, and puncture when in contact with cancellous and/or cortical bone. 
         [0035]    When compressing cancellous bone and/or creating a cavity, the expanded shape inside bone may be selected to optimize the formation of a cavity that, when filled with a selected material (e.g., PMMA, calcium phosphate, bone chips, etc.), provides support across the region of the bone being treated. In cases where the bone disease causing fracture is the loss of cancellous bone mass, as in osteoporosis, the selection of the shape of the balloon structure  106  inside bone may take into account the cancellous bone volume which should be compacted to achieve the desired therapeutic result. Another consideration for the selection of the shape of the balloon structure  106  is the amount that the targeted fractured bone region has been displaced or depressed. For example, the balloon structure  106  may have a predetermined length, such as 10 mm, 15 mm or 20 mm, selected based on the amount of displacement. The expansion of the balloon structure  106  inside a bone can elevate or push the fractured cortical wall back to or near its anatomic position occupied before fracture occurred. 
         [0036]    Referring now to  FIG. 7 , there is illustrated an implementation of the tool  100  wherein the double-threaded guidance wire  112  remains fixed to the balloon structure  106  during inflation of the balloon structure  106 .  FIG. 8  illustrates an associated operational flow diagram  300  of exemplary processes that are performed as part of a procedure using the tool  100  in such an implementation. At  302 , when the catheter tube assembly  104  of the tool  100  is delivered into a patient, the double-threaded guidance wire  112  is fixed to the distal threaded nut  130  of the balloon structure  106  (see, reference  200 ). In the delivered state, the balloon structure  106  may be folded such that the tool  100  has an axial length L. 
         [0037]    At  304 , the balloon structure  106  is then inflated with the double-threaded guidance wire  112  fixed to the distal threaded nut  130  (see, reference  202 ). The inflation of the balloon structure  106  may, e.g., compress or create a cavity within cancellous bone and/or elevate the cortical wall of the spine. As shown at  202 , the tool  100  substantially remains at the axial length L in the inflated state. 
         [0038]    At  306 , the balloon structure  106  is then deflated and the catheter tube assembly  104  may be removed at  308 . Because the double-threaded guidance wire  112  remains fixed to the balloon structure  106  through the threaded engagement of the second threaded portion  132  to the distal threaded nut  130 , the balloon structure  106  remains substantially at its original axial length L. 
         [0039]    At  310 , if the procedure using the tool  100  is completed, then the process ends  312 . However, if the procedure involves further balloon inflations, then at  310 , the catheter tube assembly  104  may be reused and reinserted (at  302 ) and the balloon structure  106  reinflated for subsequent use. Thus, the tool  100  may be reused either in the same vertebral body or another vertebral body in the same patient because the balloon structure  106  remains supported by the double-threaded guidance wire  112  and, as such, has a known size. 
         [0040]    Referring now to  FIG. 9 , there is illustrated an implementation wherein the double-threaded guidance wire  112  is removed from the balloon structure  106  during inflation of the balloon structure  106 .  FIG. 10  is an associated operational flow diagram  500  of exemplary processes that are performed as part of a procedure using the tool  100  in such an implementation. At  502 , when the catheter tube assembly  104  of the tool  100  is delivered into a patient, the double-threaded guidance wire  112  is fixed to the distal threaded nut  130  of the balloon structure  106  (see, reference  400 ). In the delivered state, the balloon structure  106  may be folded. 
         [0041]    At  504 , the double-threaded guidance wire  112  is removed, and the balloon structure  106  is then inflated at  506  (see, reference  402 ). The inflation of the balloon structure  106  compresses or creates a cavity within cancellous bone and/or elevates the cortical wall. The inflation of the expanding balloon structure  106  also expands the balloon structure  106  in the axial direction by an amount (designated by ΔL) to create an expansion area  136  that is unsupported. 
         [0042]    At  508 , the balloon structure  106  is then deflated and the double-threaded guidance wire  112  is reinserted into catheter tube assembly  104  at  510  (see, reference  404 ). For example, the double-threaded guidance wire  112  may be rotated such that the second threaded portion  132  engages the distal threaded nut  130  in the balloon structure  106 . As shown in reference  406 , the double-threaded guidance wire  112  is pulled back to engage the first threaded portion  126  within the proximal threaded nut  128 . As such, the length of the balloon structure  106  is restored to the original starting position, as indicated by the arrows and dashed lines. 
         [0043]    At  512 , the catheter tube assembly  104  may be removed. At  514 , if the procedure using the tool  100  is completed, then the process ends  516 . However, if the procedure involves further balloon inflations, then at  514 , the catheter tube assembly  104  may be reinserted (at  502 ) and the process repeats for the subsequent insertion(s). The tool  100  may be reused either in the same vertebral body or another vertebral body in the same patient. 
         [0044]    In the implementations above, the interaction of the double-threaded guidance wire  112 , proximal threaded nut  128  and distal threaded nut  130  locks the guidance wire  112  into a position such that the balloon structure  106  is returned to its original length after inflation. It is noted that any locking mechanism that returns the balloon structure  106  its original length after inflation may be used in the tool  100 . 
         [0045]    Although the distal threaded nut  130  has been described as being within the balloon structure  106 , the distal threaded nut may be either inside or outside of the balloon structure  106 . For example, the thread may be part of a rivet that is outside the balloon structure  106  and forms part of a tip of the balloon structure  106 . 
         [0046]    The subject matter described above is provided by way of illustration only and should not be construed as limiting. Various modifications and changes may be made to the subject matter described herein without following the example embodiments and applications illustrated and described, and without departing from the true spirit and scope of the present invention, which is set forth in the following claims.