referring now to fig1 - 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 . as best shown in fig1 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 . as shown in fig1 , 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 . 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 . as shown in fig2 , 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 ., fig1 ) 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 . with reference to fig1 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 . 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 . 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 fig7 - 10 . in some implementations , as shown in fig4 , 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 fig3 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 . 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 . 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 . referring now to fig7 , 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 . fig8 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 . 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 . 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 . 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 . referring now to fig9 , 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 . fig1 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 . 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 . 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 . 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 . 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 . 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 . 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 .