Patent Publication Number: US-2012041462-A1

Title: Apparatus for forming hole in spongelike bone

Description:
TECHNICAL FIELD 
     The present invention relates generally to an apparatus for forming a hole in a spongelike bone and, more particularly, to a structure of a catheter and an expansible structure that is coupled to an upper portion of the catheter structure. 
     BACKGROUND ART 
     A spinal curvature restoration procedure is an operating procedure wherein a damaged vertebra is restored to its original height and angle in a kyphosis, and then a bone filler is injected into the damaged vertebra to stabilize it. This operation is generally performed percutaneously, and the restoration of the height and angle of the vertebra is done by intravertebral expansion based on the pressure of liquid or a mechanical method up to now. 
     A typical apparatus used in the spinal curvature restoration procedure is made up of a needle and a wire pin, a cannula and an expander, and a cement filler and a pusher. Here, depending on whether or not a balloon catheter is used, spinal curvature restoration procedures are divided into a typical restoration procedure and a balloon restoration procedure. 
     Making reference to the balloon restoration procedure in detail, an elongated special tube is inserted into a compression curvature region. A balloon is inserted into the region through the tube, and then is expanded up to a normal height of the vertebra. Then, the balloon is removed, and the hole formed by the removal of the balloon is filled with bone cement. 
     An example of the apparatus for forming the hole used in the above-mentioned procedure is disclosed in Korean Patent No. 10-0793005. As shown in  FIG. 1 , such an apparatus  76  includes: a catheter tube  78  that has a proximal end  80 , a distal end  82 , a first lumen  88 , and a second lumen  94 ; an expansible structure  86  such as a balloon that is supported on the distal end of the catheter  78 , has a tip, and communicates with the first lumen  88  of the catheter  78 ; and a probe  96  that is removably inserted into the second lumen of the catheter tube  78 . The second lumen  94  in a tool  76  that is extended to the tip of the expansible structure  86  through the first lumen  88  of the catheter tube. 
     However, since the tool  76  forming the hole includes the first lumen  88 , the second lumen  94 , and the probe  96 , it has a very complicated structure that makes the cost of production high. Further, since the probe  96  made of metal extends to the tip of the expansible structure  86 , there is a fear that bringing the metal probe into contact with a human body will cause problems when the expansible structure  86  bursts. Thus, a method capable of solving this problem is being sought out. 
     Further, as shown in  FIG. 7 , the expansible structure (e.g. the balloon) that has been generally used in the related art is formed of an elastomer having a single composition, and there is always a chance that it will burst during an operation. When the expansible structure (e.g. the balloon) is burst, a fragment of the expansible structure (e.g. the balloon) may remain in the bone without being recollected in addition to the problem that the metal probe is brought into contact with the human body. As a result, the operation may be delayed, which increases the pain of a patient. Accordingly, a study into improving this problem is required. 
     DISCLOSURE 
     Technical Problem 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an objective of the present invention is to provide an apparatus for forming a hole in a spongelike bone, which simplifies the structure of a conventional apparatus for forming a hole in a spongelike bone with its functionality maintained without a change, and which is a very economical apparatus. 
     Another objective of the present invention is to provide an apparatus for forming a hole in a spongelike bone, in which the diameter of a catheter tube is remarkably reduced by the structural simplification as described above. 
     Yet another objective of the present invention is to provide an expansible structure (e.g. a balloon) which improves a conventional expansible structure having a mono-layer structure so as to have a multi-layer structure including a reticular structure, thereby minimizing a bursting possibility, and which is used to form a hole in a human body in which the position and expanded shape of the balloon can be monitored without using a marker of platinum and an expensive contrast medium depending on a material of the reticular structure. 
     Technical Solution 
     In order to accomplish the above objectives, the present invention provides an apparatus for forming a hole in a spongelike bone, which includes: a catheter tube; an expansible structure coupled to a front end of the catheter tube; a hub having a fitting coupled to a rear end of the catheter tube; and a probe, wherein the catheter tube includes the probe and one lumen surrounding the probe, both of which are disposed inside the catheter tube, and the probe is fixed to the hub or a rear cap of the hub at a rear end thereof and comes into contact with an inner front end of the expansible structure at a front end thereof. 
     Here, the front end of the catheter tube may extend to the inner front end of the expansible structure, and the extension part of the catheter tube may include at least one fluid inflow and outflow hole. 
     Further, the expansible structure may have a balloon shape and be formed by coating a reticular structure formed of a polymer or metal material with a polymer. 
     In order to accomplish the above objectives, the present invention provides an expansible structure used in an apparatus for forming a hole in a spongelike bone, which has a balloon shape and is formed by coating a reticular structure formed of a polymer or metal material with a polymer. 
     Advantageous Effects 
     According to the present invention, the apparatus for forming a hole in a spongelike bone is improved and made into a simple structure by removing a tube structure forming a conventional second lumen, thereby providing easy production, convenient usage, and high economical benefits. 
     Further, the diameter of the catheter tube is reduced by the structural simplification as described above, and thus an insertion hole which is formed in a human body as part of an operation to make way for the apparatus can be reduced in size. Thus, the effect of reducing the pain of a patient and the effect of facilitating the operation are provided. 
     Further, the catheter tube extends to the inner front end of the expansible structure (e.g. the balloon), and the fluid inflow and outflow hole is formed in the extension part of the catheter tube. Thereby, it is possible to feed and recollect fluid into and from the expansible structure in a rapid, easy manner. Thus, the inventive apparatus provides the effects of cutting back on operating time and facilitating the operation. 
     According to the present invention, the expansible structure is improved so as to have a multi-layer structure of the reticular structure formed of a polymer or metal material and the polymer coating the reticular structure, so that it is allowed to minimize a possibility of being burst in the human body. Further, when the reticular structure is formed of a metal material, the reticular structure itself is displayed on an X-ray monitor. As such, it is easy to check position and expanded shape of the balloon, and thus a higher precision operation is possible. Further, since it is unnecessary to separately use the marker made of platinum and the expensive contrast medium, the expansible structure is very economical. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIGS. 1 and 2  show a conventional apparatus for forming a hole in a spongelike bone; 
         FIG. 3  shows an apparatus for forming a hole in a spongelike bone according to an embodiment of the present invention; 
         FIG. 4  shows a probe integrally formed with a hub in the apparatus for forming a hole in a spongelike bone according to the embodiment of the present invention; 
         FIG. 5  shows an extension part of a catheter tube in the apparatus for forming a hole in a spongelike bone according to the embodiment of the present invention; 
         FIG. 6  shows the extension part of the catheter tube and the probe integrally formed with the hub in the apparatus for forming a hole in a spongelike bone according to the embodiment of the present invention; 
         FIG. 7  shows a conventional expansible structure having only elastomer layer used to form the hole in a human body, wherein  FIG. 7(   a ) is for the expansible structure before expansion and  FIG. 7(   b ) is for the expansible structure after expansion; 
         FIG. 8  shows a reticular structure constituting an inventive expansible structure used to form the hole in the human body; 
         FIG. 9  is a photograph of the reticular structure constituting the inventive expansible structure used to form the hole in the human body, wherein  FIG. 9(   a ) is for the reticular structure knitted with fibriform polymer wires, and  FIG. 9(   b ) is for the reticular structure knitted with metal wires; 
         FIG. 10  shows the metal wire having a tensile spring shape forming the reticular structure used in the inventive expansible structure, wherein  FIG. 10(   a ) is of the metal wire before expansion, and  FIG. 10(   b ) is of the metal wire after expansion; 
         FIG. 11  shows the inventive expansible structure used to form the hole in the human body, wherein  FIG. 11(   a ) is the expansible structure before expansion, and  FIG. 11(   b ) is the expansible structure after expansion; and 
         FIG. 12  shows a partial cross section of the inventive expansible structure. 
     
    
    
     BRIEF DESCRIPTION OF SYMBOLS USED IN DRAWINGS 
       
     
       
         
           
               
               
             
               
                   
               
             
            
               
                  10: catheter tube 
                 11: lumen 
               
               
                  12: extension part of catheter tube 
                 13: fluid inflow and outflow hole 
               
               
                  14: fibriform polymer or metal wire 
               
               
                  15: expansion allowance 
                 16: metal wire having tensile 
               
               
                   
                 spring shape 
               
               
                  20: probe (or support rod) 
                 21: marker 
               
               
                  30: hub 
                 31: fitting 
               
               
                  40: hub rear cap 
                 50: expansible structure 
               
               
                  51: reticular structure 
                 52: polymer for coating 
               
               
                 100: apparatus for forming hole in 
               
               
                 spongelike bone 
               
               
                   
               
            
           
         
       
     
     BEST MODE 
     Reference now should be made to the different drawings, throughout which the same reference numerals are used to designate the same or similar components. The detailed descriptions of known functions and constructions unnecessarily obscuring the subject matter of the present invention will be avoided below. 
     As shown in  FIGS. 3 and 4 , the present invention is directed to an apparatus  100  for forming a hole in a spongelike bone, which includes a catheter tube  10 , an expansible structure  50  coupled to a front end of the catheter tube, a hub  30  having a fitting  31  coupled to a rear end of the catheter tube, and a probe  20 . The catheter tube  10  is made up of the probe (also called a “support rod”)  20  and one lumen  11  surrounding the probe, both of which are disposed inside the catheter tube. The probe  20  is fixed to the hub  30  or a rear cap  40  of the hub at a rear end thereof, and comes into contact with an inner front end of the expansible structure  50  at a front end thereof. 
     Further, as shown in  FIGS. 5 and 6 , the present invention is directed to an apparatus  100  for forming a hole in a spongelike bone, in which the front end of the catheter tube extends to the inner front end of the expansible structure  50 , and the extension part  12  of the catheter tube has at least one fluid inflow and outflow hole  13 . 
     In the present invention, since the catheter tube  10  is provided therein with only one lumen  11 , it is possible for the catheter tube  10  to be configured to have a smaller diameter than a conventional catheter tube. Thus, a hole formed in a human body for the purpose of the operation can be reduced in diameter, so that the catheter tube  10  can provide the effect of reducing the pain of a patient and the effect of getting the patient to rapidly recover following the operation. 
     The extension part  12  of the catheter tube may be formed in a structure where a diameter thereof is smaller than that of the catheter tube  10  from the hub  30  to a portion coupled with the expansible structure  50 . The structure of the catheter tube extension part  12  facilitates the insertion of the expansible structure  50  into an operating region in the event of an operation. 
     The desired number of fluid inflow and outflow holes  13  formed in the catheter tube extension part  12  ( FIG. 5 ) may be selected after taking into consideration the flow rate of fluid that flows in and out through the lumen  11  inside the catheter tube  10 . The fluid inflow and outflow hole  13  is not substantially limited to its shape as long as it does not hinder the fluid from flowing in and out. When the fluid inflow and outflow hole  13  is formed at an end of the extension part  12 , this provides the effect of more easily recollecting the fluid contained in the inner front end of the expansible structure  50 . 
     A front end of the catheter tube extension part  12  may be formed to be blocked. 
     The catheter tube extension part  12  may be attached with at least one marker  21 , the position of which can be detected, for instance, by X-rays. For example, the markers  21  may be attached to respective portions of the catheter tube extension part  12  which are located at an entrance portion and the front end of the expansible structure  50 . 
     As a material of the catheter tube  10 , any material may be used as long as the catheter tube can move forward through the cannula instrument. For example, the catheter tube may be made using a surgical grade plastic material having excellent flexibility, such as vinyl, nylon, polyethylene, ionomer, polyurethane, polyethyleneterephthalate (PET), or the like. Further, a harder material may be selected to enhance rigidity and manipulability. 
     The lumen formed in the catheter tube  10  communicates with the expansible structure  50  and the fitting  31 . The fitting  31  serves to connect the lumen to a fluid source, for instance, a sterilized salt water source or a radiopaque contrast medium source. 
     The probe  20  is fixed to the rear cap  40  of the rear end of the hub  30 , and is inserted through a passage in the hub  30  and the lumen  11  inside the catheter tube to the front end of the expansible structure  50 . If necessary, the probe  20  may be formed in a separable structure. 
     As shown in  FIGS. 4 and 6 , the probe  20  may, however, be integrally formed with the hub  30  or fixed to the hub  30  by an adhering method. 
     As material for the probe  20 , metal materials or polymers such as plastics which are available for medical use may be used without restriction. Among them, the material of the probe  20  may be selected in consideration of strength required for the probe  20 , physical properties required for integration with the hub  30 , adhesion to the hub  30 , and so on. It is particularly preferable that the probe  20  be made of polymer, because it is possible to avoid problems that are caused by direct contact of the probe of metal with the human body even if the expansible structure  50  were to burst. 
     The probe  20  functions to keep the expansible structure  50  linear at a distal end of the catheter until the catheter  100  runs through the cannula instrument to reach a target tissue region. Once the expansible structure  50  leaves the cannula instrument to be placed inside the bone, the probe  20  can be extracted. Thereby, it is possible to increase flexibility of the catheter tube  10 , and to easily manipulate the expansible structure  50  in the bone. 
     The probe  20  may have a linear shape, or another shape where its end region can be bent at a desired point of time by providing a previously formed memory. In the case of providing the memory, the probe  20  is in the linear shape by overcoming the memory when kept in the cannula instrument. As the probe  20  leaves the cannula instrument to move into a target region, the end region of the probe  20  is bent by the previously formed memory, so that a major axis of the expansible structure  50  is shifted. In this case, a direction of the expansible structure  50  may be changed by the probe  20  that is previously bent in the expansible structure  50 , and the anatomical alignment with the target region is made more excellent. 
     A part of the probe  20 , which extends to the inside of the expansible structure  50 , may be attached with at least one marker  21 , the position of which can be detected, for instance, by X-rays. For example, the markers  21  may be attached to respective portions that are located at the entrance portion and the front end of the expansible structure  50 , within the part of the probe  20  which extends to the inside of the expansible structure  50 . 
     For the apparatus  100  for forming a hole in a spongelike bone according to the present invention, a variety of types of expansible structures  50  may be used. Particularly, the expansible structure  50  having a balloon shape may be used. As the balloon-shaped expansible structure  50 , ones known in the related art may be used without restriction. However, to reduce the possibility of being burst in the human body, one formed by coating a reticular structure  51  formed of polymer or metal with a polymer  52 , as shown in  FIG. 8  can be used. When the reticular structure  51  is formed of metal, the reticular structure itself is displayed on an X-ray monitor. As such, it is easy to check the position and expanded shape of the balloon, and thus a higher precision operation is possible. Further, due to this advantage, it is unnecessary to separately use the marker made of platinum and the expensive contrast medium, so that economical benefits are provided. The expansible structure  50  will be described below in greater detail. 
     Further, as shown in  FIGS. 8 through 12 , the present invention is directed to the expansible structure  50  used in the apparatus  100  for forming a hole in a spongelike bone, in which the polymer  52  is coated on the reticular structure  51  formed of polymer or metal. 
     In the present invention, the reticular structure  51  refers to a structure in which a plurality of holes are formed by a crossed polymer or metal material regardless of a structure, and should be genetically interpreted. For example, the reticular structure  51  may include a structure manufactured by crossing several fibriform polymer or metal wires, or a structure manufactured by knitting the fibriform polymer or metal wires in the form of a knitted fabric. 
     However, in the present invention, since the reticular structure formed of the polymer or metal material should be expanded when the balloon is expanded, it is preferable to use the reticular structure manufactured by knitting the fibriform polymer or metal wires in the form of a knitted fabric, as shown in  FIG. 8 . This is because, when the reticular structure is knitted with the fibriform polymer or metal wires, expansion allowances  15 , which allow the reticular structure  51  to be expanded when the balloon is expanded, are generated between loops, so that the balloon can expand smoothly. 
     Here, the method used to adjust the expansion allowances  15  may be a knitting method. 
       FIGS. 8(   a ) and  8 ( b ) show tubular reticular structures  51  knitted by different methods. It can be seen from the state where the fibriform polymer or metal wires  14  are knitted to form the reticular structure  51  that the expansion allowances  15 , which allow the reticular structure  51  to be expanded when the expansible structure  50  is expanded, are formed between the loops. 
     A photograph shown in  FIG. 9  is an actual photograph of the reticular structure  51  used in the present invention.  FIG. 9(   a ) is a photograph of the reticular structure  51  formed of the fibriform polymer, and  FIG. 9(   b ) is a photograph of the reticular structure  51  knitted with the metal wires. In the photographs, a member located below the reticular structure  51  is a polymer  52  tube for coating, and is used to coat the inside of the reticular structure  51  when the reticular structure  51  is formed in a balloon shape. 
     In the present invention, when the reticular structure  51  is formed of a metal material, the metal wires forming the reticular structure preferably have the shape of a tensile spring  16 , as shown in  FIG. 10 . This is because it is possible to secure the expansion allowances  15  by the knitting method as described above, but when the metal wires having the shape of the tensile spring  16  are used, the reticular structure may be more smoothly expanded and contracted when the balloon is expanded and removed. Thus, when the reticular structure  51  is manufactured using the metal wires having the shape of the tensile spring  16 , there is no fear of the expansible structure  50  including such a reticular structure  51  being destroyed during the operation. Further, since the reticular structure itself is displayed on the X-ray monitor, it is easy to check the position and expanded shape of the expansible structure  50 , and thus a higher precision operation is possible. Further, since the expansible structure  50  is contracted and reduced in volume when removed, it is easily removed. 
     In the present invention, the kind of metal material used for the reticular structure  51  is not substantially restricted. However, since the metal material is used in the human body, it is preferable to use a material suitable for medical use such as stainless steel. 
     A diameter of the metal wire used as the metal material is not substantially restricted. However, the diameter of the metal wire should be suitable to form the expansible structure. For example, the diameter of the metal wire may range from about 0.001 mm to about 0.1 mm. Further, when the metal wire has the tensile spring shape, the diameter of the metal wire may range from about 0.005 mm to about 0.3 mm. 
     In the present invention, the reticular structure  51  may be knitted with one strand of the fibriform polymer or metal wires or two or more strands of the fibriform polymer or metal wires. Here, to manufacture the reticular structure in a firm structure, the reticular structure is preferably knitted with one strand of the fibriform polymer or metal wires. 
     In the expansible structure  50  of the present invention, a kind of the polymer that is used to form the reticular structure  51  is not substantially restricted. However, a polymer having excellent strength and elongation is preferable. For example, elastomer, Peek®, silicon, latex, or the like may be used. The elastomer may include nylon, polyurethane, polyethylene, polypropylene, polystyrene, and so on. Among them, the Peek® is a polymer material that has been proven to not be harmful to the human body and that is thought to be one of thermoplastic materials exhibiting the highest functionality, and is currently used as an implant material in connection with a spine (see the website http://www.victrex.com). Particularly, as the polymer material used to form the reticular structure  51 , nylon, Peek®, polyurethane, or the like may be used. 
     In the present invention, as the polymer  52  that coats and seals the reticular structure, a typical material used in the related art may be used without a restriction, and a polymer having excellent strength and elongation is preferable. For example, elastomer, Peek®, silicon, latex, or the like may be used. The elastomer may include nylon, polyurethane, polyethylene, polypropylene, polystyrene, and so on. 
     In the present invention, as the polymer used to form the reticular structure  51  and the polymer  52  used to coat and seal the reticular structure  51 , a homogeneous or heterogeneous polymer may be used. 
     In the present invention, when the reticular structure  51  is formed of the polymer, a ratio of tensile strength of the polymer  52  for coating the reticular structure to that of the polymer used to form the reticular structure  51  is 1:0.5 to 1:10, preferably 1:1.0 to 1:3.0. If the tensile strength of the polymer used to form the reticular structure  51  is 0.5 times less than that of the polymer  52  for coating the reticular structure, it is difficult to sufficiently obtain the desired effects. In contrast, if the tensile strength of the polymer used to form the reticular structure  51  is 10 times more than that of the polymer  52  for coating the reticular structure, only the polymer  52  for coating the reticular structure is elongated (expanded), and thus there is a chance of increasing the danger of bursting. Thus, the tensile strength of the polymer  52  for coating the reticular structure and the tensile strength of the polymer used to form the reticular structure  51  are selected in consideration of the characteristics of the respective polymers, and preferably are within a proper range on the basis of the predicted behaviors of the respective polymers when the balloon is expanded. 
       FIG. 11  shows an example of the expansible structure  50  of the present invention, wherein  FIG. 11(   a ) shows the shape before expansion, and  FIG. 11(   b ) shows the shape after expansion. In  FIG. 11(   a ), the expansion allowances  15  allow the reticular structure  51  to be expanded so that the balloon is expanded to a predetermined size when fluid flows into the expansible structure  50 . 
     In the expansible structure  50  of the present invention, a laminated structure in which the polymer  52  for coating the reticular structure is coated on the reticular structure  51  formed of the polymer or metal material is as shown in  FIG. 12 . In detail, the laminated structure may include a structure in which the polymer  52  for coating the reticular structure is coated on an outer surface of the reticular structure  51  as in  FIG. 12(   a ), a structure in which the polymer  52  for coating the reticular structure is coated on outer and inner surfaces of the reticular structure  51  to form a sandwich structure as in  FIG. 12(   b ), and a structure in which the polymer  52  for coating the reticular structure is coated on an inner surface of the reticular structure  51  as in  FIG. 12(   c ). 
     The method of manufacturing the expansible structure  50  of the present invention is not substantially restricted. For example, a known method of manufacturing a hose including a reticular structure may be used for reference. For example, the reticular structure is primarily knitted with the fibriform polymer or metal wires on an outer surface of a tube, which has been primarily extruded using a polymer material such as elastomer, using a knitting machine (see  FIG. 9 ). Then, the knitted reticular structure is secondarily coated with a polymer material such as elastomer, and is cut into a proper size and formed into balloon shape. Thereby, the expansible structure  50  of the present invention is finished. 
     The inventive balloon used to form a hole in a human body may be applied to various fields. For example, the inventive balloon may be very useful for a balloon catheter used for the balloon treatment of vertebral compression fractures. 
     Although the embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.