Abstract:
Disclosed herein are devices for use through a cannula to create cavities within interior body regions. When deployed, the distal end of several such devices extend beyond the distal end of the catheter and can then be selectively curved into a shaped compression surface that, when articulated, creates a void within the interior body. This compression surface may then be withdrawn back into the cannula for removal and to make way for bone cement that, in certain instances, may be introduced through the same cannula.

Description:
BACKGROUND 
     Certain diagnostic or therapeutic procedures require the formation of a cavity in an interior body region. These cavity-forming procedures can be used to treat cortical bone which due to osteoporosis, avascular necrosis, cancer, or trauma, for example, may be fractured or prone to compression fracture or collapse and which, if not successfully treated, can lead to deformities, chronic complications, and an overall adverse impact upon the quality of life for the patient. 
     Vertebroplasty is where a medical-grade bone cement (such as polymethylmethacrylate, a.k.a., PMMA) is injected percutaneously via a catheter into a fractured vertebra. In this procedure, the bone cement is injected with enough pressure to enable the cement to compress and displace cancellous bone tissue. However, the direction and containment of the injected cement can be difficult to control since the space the bone cement will ultimately occupy is ill-defined, self-forming, and highly-dependent upon the internal composition of the cancellous bone in the vicinity of the injection. 
     To provide better bounding and control over injected bone cement, other procedures utilize devices for first forming cavities within the cancellous bone (and, accordingly, other interior body regions) prior to injecting bone cement into such a cavity. For example, some devices may utilize an expandable body or balloon that is deployed into the interior body region to form a cavity in, for example, cancellous bone tissue. These expandable body devices effectively compress and displace the cancellous bone to form an interior cavity that then receives a filling material intended to provide renewed interior structural support for cortical bone. However, the effectiveness of expandable or inflatable devices can still be negatively impacted by the internal composition of the cancellous bone in the vicinity of their use—unbeknownst to the surgeon performing the procedure because of a lack of tactile feedback—and removing the expandable or inflatable device may be difficult in certain applications of such processes. 
     SUMMARY 
     Various embodiments disclosed herein pertain to devices to create cavities within interior body regions. When deployed though a cannula emplaced into cancellous bone, for example, the distal end of the device can be extended beyond the distal end of the catheter and then be selectively curved into various shaped compression surfaces that, when rotated about a longitudinal axis, creates a void within the interior body. This extended compression surface can then be withdrawn back into the cannula for complete removal from the cannula, and a void filler such as bone cement may then be introduced into the void. For certain embodiments, this bone cement may be introduced through the same cannula used by the cavity creation device. 
     More specifically, certain embodiments disclosed herein are directed to an articulated tip assembly for creating a cavity in a body, the articulated tip assembly comprising a coil enclosure having a proximal end and a distal end (the coil enclosure being curvable), a shaft coupler coupled to the proximal end of the coil enclosure, a plurality of interconnecting curving elements enclosed within the coil enclosure and movably coupled to the shaft coupler, and a tip coupled to the distal end of the coil enclosure and coupled to the plurality of interconnecting curving elements. 
     Other implementations are directed to a device for creating a cavity in an interior body, the device comprising an articulated tip assembly, a shaft coupled to the articulated tip assembly, a lever assembly coupled to the shaft, and an off-center cable coupled to the articulated tip assembly and the lever assembly such that variable action of the lever assembly causes the articulated tip assembly to selectively curve, wherein rotation of the device causes the articulated tip assembly to rotate within the interior body. Yet other embodiments are directed to methods for creating a cavity in a target body using an articulated cavity creator, the method comprising inserting an articulated tip assembly into the target body, curving and rotating the articulated tip assembly, and then withdrawing the articulated tip assembly. 
     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 to be used to limit the scope of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1A  is a perspective view of an articulated cavity creator representative of various embodiments disclosed herein; 
         FIG. 1B  is a side view of the articulated cavity creator of  FIG. 1A ; 
         FIG. 1C  is a bottom view of the articulated cavity creator of  FIGS. 1A and 1B ; 
         FIG. 1D  is a exploded perspective view of the articulated cavity creator of  FIGS. 1A ,  1 B, and  1 C; 
         FIG. 2A  is an exploded perspective view of an exemplary tip assembly comprising the distal end of an articulated cavity creator representative of several embodiments disclosed herein; 
         FIG. 2B  is a side view of the exemplary tip assembly of  FIG. 2A  in a curved configuration; 
         FIG. 3A  is a perspective view of a cavity creator tip representative of various embodiments disclosed herein; 
         FIG. 3B  is a cross-sectional top view of the cavity creator tip of  FIG. 3A ; 
         FIG. 3C  is a side view of the cavity creator tip of  FIGS. 3A and 3B ; 
         FIG. 3D  is a proximal end view of the cavity creator tip of  FIGS. 3A ,  3 B, and  3 C; 
         FIG. 4A  is a perspective view of a cavity creator curving element representative of various embodiments disclosed herein; 
         FIG. 4B  is a distal end view of the cavity creator curving element of  FIG. 4A ; 
         FIG. 5A  is a perspective view of a cavity creator shaft coupler representative of various embodiments disclosed herein; 
         FIG. 5B  is a side view of the cavity creator shaft coupler of  FIG. 5A ; 
         FIG. 6  is a side view of a cavity creator coil enclosure representative of various embodiments disclosed herein; 
         FIG. 7A  is an exploded perspective view of an exemplary lever assembly of an articulated cavity creator representative of several embodiments disclosed herein; 
         FIG. 7B  is an exposed side view of the exemplary lever assembly of  FIG. 7A ; 
         FIG. 8A  is side view of an exemplary rotation shaft of an articulated cavity creator representative of several embodiments disclosed herein; 
         FIG. 8B  is a cross-sectional view of the exemplary rotation shaft of  FIG. 8A ; 
         FIG. 9  is an exploded perspective view of an exemplary tensioner assembly comprising the proximal end of an articulated cavity creator representative of several embodiments disclosed herein; 
         FIG. 10A  is a perspective view of a cavity creator tensioner representative of various embodiments disclosed herein; 
         FIG. 10B  is a cross-sectional top view of the cavity creator tensioner of  FIG. 10A ; 
         FIG. 10C  is a partially-cross-sectional side view of the cavity creator tensioner of  FIGS. 10A and 10B ; 
         FIG. 10D  is a distal end view of the cavity creator tensioner of  FIGS. 10A ,  10 B, and  10 C; 
         FIG. 11A  is a perspective view of a cavity creator tension knob representative of various embodiments disclosed herein; 
         FIG. 11B  is a side view of the cavity creator tension knob of  FIG. 11A ; 
         FIG. 11C  is a cross-sectional side view of the cavity creator tension knob of  FIGS. 11A and 11B ; 
         FIG. 11D  is a proximal end view of the cavity creator tension knob of  FIGS. 11A ,  11 B, and  11 C; 
         FIG. 12A  is a perspective view of a maximum cavity creatable utilizing certain embodiments of the cavity creator disclosed herein; 
         FIG. 12B  is a side view of the maximum cavity of  FIG. 12A  further including the tip assembly of  FIG. 2  in position within the interior body; and 
         FIG. 12C  is an operational flow diagram illustrating a method for creating the cavity illustrated in  FIGS. 12A and 12B  utilizing certain embodiments of the cavity creator disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     Certain terminology is used in the following description for convenience only and is not limiting. The words “right”, “left”, “lower”, and “upper” designate direction in the drawings to which reference is made. The words “inner”, “outer” refer to directions toward and away from, respectively, the geometric center of the described feature or device. The words “distal” and “proximal” refer to directions taken in context of the item described and, with regard to the instruments herein described, are typically based on the perspective of the surgeon using such instruments. The words “anterior”, “posterior”, “superior”, “inferior”, “medial”, “lateral”, and related words and/or phrases designate preferred positions and orientation in the human body to which reference is made. The terminology includes the above-listed words, derivatives thereof, and words of similar import. 
     In addition, various components may be described herein as extending horizontally along a longitudinal direction “L” and lateral direction “A”, and vertically along a transverse direction “T”. Unless otherwise specified herein, the terms “lateral”, “longitudinal”, and “transverse” are used to describe the orthogonal directional components of various items. It should be appreciated that while the longitudinal and lateral directions are illustrated as extending along a horizontal plane, and that the transverse direction is illustrated as extending along a vertical plane, the planes that encompass the various directions may differ during use. Accordingly, the directional terms “vertical” and “horizontal” are used to describe the components merely for the purposes of clarity and illustration and are not meant to be limiting. 
       FIG. 1A  is a perspective view of an articulated cavity creator  100  representative of various embodiments disclosed herein.  FIG. 1B  is a side view of the articulated cavity creator  100  of  FIG. 1A .  FIG. 1C  is a bottom view of the articulated cavity creator  100  of  FIGS. 1A and 1B .  FIG. 1D  is a exploded perspective view of the articulated cavity creator  100  of  FIGS. 1A ,  1 B, and  1 C. 
     Referring to  FIGS. 1A ,  1 B,  1 C, and  1 D (collectively referred to herein as “FIG.  1 ”), an articulated cavity creator (“ACC”) may comprise a tip assembly  200 , an intra-catheter shaft  300 , a lever assembly  400 , a rotation shaft  500 , and a tensioner assembly  600 , each operatively coupled in order from distal end to proximal end of the ACC as shown in  FIG. 1 . The ACC further comprises an off-center cable  120  and a midline cable  140 . The off-center cable  120  is fixedly coupled to the lever assembly  400  at its proximal end, passes longitudinally through the intra-catheter shaft  300 , and is fixedly coupled to the tip assembly  200  at its distal end. The midline cable  140 , in contrast, is effectively doubled-backed on itself with both ends  142  and  144  fixedly coupled to the tip assembly  200  and passing longitudinally through the intra-catheter shaft  300 , the lever assembly  400 , the rotation shaft  500 , and operationally coupling a rotational component  602  of the tensioner assembly  600  at its bend  146 . Each of these components and theirs functions are described in greater detail herein. 
       FIG. 2A  is an exploded perspective view of an exemplary tip assembly  200  comprising the distal end of an articulated cavity creator  100  representative of several embodiments disclosed herein.  FIG. 2B  is a side view of the exemplary tip assembly  200  of  FIG. 2A  in a curved configuration. 
     Referring to  FIGS. 2A and 2B  (collectively referred to herein as “FIG.  2 ”), the tip assembly  200  may comprise a cavity creator tip  210 , a plurality of interconnecting curving elements  230 , a coil enclosure  250 , and shaft coupler  260  for coupling to the intra-catheter shaft  300 . As shown in  FIG. 2B , the proximal end  212  of the tip  210 , the curving elements  230 , and the distal end  264  of the shaft coupler  260  are movably coupled and enclosed within the hollow created by the coil enclosure  250 , thereby exposing the distal end  214  of the tip  210  beyond the distal end  254  of the coil enclosure  250 , as well as exposing the proximal end  262  of the shaft coupler  260  beyond the proximal end  252  of the coil enclosure  250 . Moreover, in several alternative embodiments the coil enclosure  250  may be replaced with other enclosures such as a sheath or a series of rings, for example, and that such alternative enclosures may be constructed of any of several suitable materials, including but not limited to rubber, latex, plastic or nitinol. 
     Further shown in  FIG. 2B  is the distal end of the doubled-back midline cable  140  running on both sides of the tip assembly  200  (one strand shown, the other strand behind and obstructed from view), both ends of which are fixedly coupled to the tip  210  and run down concurrent lateral channels (highlighted in other illustrations) on each side of the tip  210 , the curving elements  230 , and the shaft coupler  260 , and thereby pass through the hollow of the coil enclosure  250  and through the intra-catheter shaft  300 . This midline cable  140  provides the tension necessary to hold the tip  210 , the curving elements  230 , and the shaft coupler  260  movably coupled and enclosed within the hollow created by the coil enclosure  250 . Through the application of even tension by both strands of the midline cable  140 , curving of the tip assembly  200  in a vertical (up-and-down) direction is achievable as disclosed herein. 
     Also shown in  FIG. 2B  is the distal end of the off-center cable  120  fixedly coupled to the tip  210  and running down a top channel (highlighted in other illustrations) of the tip  210 , the curving elements  230 , and the shaft coupler  260 , and thereby passing through the hollow of the coil enclosure  250  and the intra-catheter shaft  300 . This off-center cable  120  provides variable tension on the top side of the tip assembly  200  causing the tip  210 , the curving elements  230 , and the shaft coupler  260  to together movably curve against the coil enclosure  250  (as shown) in various curved configurations depending on the amount of variable tension applied by the off-center cable  120 . As such, the curving elements  230  within tip assembly  200  cooperate to approximate a curved shape. Further, the tip assembly  200  may form such a curved shape around any object that the tip assembly  200  encounters as the off-center cable  120  is tensed along the top side of the tip assembly  200 . 
     The aforementioned curvable motions and restrictions of the tip assembly  200  are further complimented by the shaping of the proximal end  212  of the tip  210 , both ends of the curving elements  230 , and the distal end  264  of the shaft coupler  260 , which help assist curving of the tip assembly  200  in a vertical direction and help prevent curving in a horizontal direction. This shaping is discussed in greater detail later herein. 
       FIG. 3A  is a perspective view of a cavity creator tip  210  representative of various embodiments disclosed herein.  FIG. 3B  is a cross-sectional top view of the cavity creator tip  210  of  FIG. 3A .  FIG. 3C  is a side view of the cavity creator tip  210  of  FIGS. 3A and 3B .  FIG. 3D  is a proximal end view of the cavity creator tip  210  of  FIGS. 3A ,  3 B, and  3 C. 
     Referring to  FIGS. 3A ,  3 B,  3 C, and  3 D (collectively referred to herein as “FIG.  3 ”), the cavity creator tip  210  (or simply “tip”) comprises a partial curving element  222  corresponding to the proximal end  212  and a head  224  corresponding to the distal end  214 . The partial curving element  222  further comprises two lateral channels  216 , one oriented to each side of the tip  210 , as well as a top channel  220  oriented to the top of the tip  210 . These channels  216  and  220  proceed through the head  224  to open at the distal end of the tip  210  as shown in the illustrations, and for certain embodiments these distal endpoints for the channels  216  and  220  at the head  224  may comprise fastening or welding points for fixedly coupling the both ends  142  of the doubled-back midline cable  140 , as well as the distal end of the off-center cable  120 , to the tip  210 . The head  224  may also comprise a distal edge  226  that is vertically flat (as shown) or, in other embodiments, may be formed to provide a rounded edge or an edge of some other form or shape. The head also comprises a stop surface  228  for engaging but not passing into the distal end of the coil enclosure  250 . 
     The partial curving element  222 , insertable into the distal end of the coil enclosure  250 , further comprises a partially-cylindrical convex proximal male end  202  for operatively coupling to a corresponding partially-cylindrical distal female end of a curving element  230  to facilitate curving of the tip assembly  200  in a vertical direction and help prevent curving in a horizontal direction (the partially-cylindrical shape being curved in the vertical direction but flat in the horizontal direction). Similarly, the two lateral channels  216  each comprise a slope surface  218  to allow curving of a tip assembly  200  in a vertical “up” direction (but not in a vertical “down” direction) against each strand of the midline cable  140  running through said lateral channels  216 . 
       FIG. 4A  is a perspective view of a cavity creator curving element  230  representative of various embodiments disclosed herein.  FIG. 4B  is a distal end view of the cavity creator curving element  230  of  FIG. 4A . 
     Referring to  FIGS. 4A and 4B  (collectively referred to herein as “FIG.  4 ”), each such curving element  230  comprises two lateral channels  216 , one oriented to each side of the curving element  230 , as well as a top channel  220  oriented to the top of the curving element  230 . The curving element  222  further comprises a partially-cylindrical convex proximal male end  202  and a partially-cylindrical concave proximal female end  204 . The proximal male end  202  is shaped to operatively couple with the corresponding distal female end  204  of either another curving element  230  or shaft coupler  260 . Conversely, the distal female end  204  is shaped to operatively couple with the corresponding proximal male end  202  of either another curving element  230  or the distal end  212  of the tip  210  accordingly. 
     Both the proximal male end  202  and the distal female end  204  of the curving element  230  facilitate curving of the tip assembly  200  in a vertical direction and help prevent curving in a horizontal direction (the partially-cylindrical shape being curved in the vertical direction but flat in the horizontal direction). Similarly, the two lateral channels  216  each comprise a slope surface  218  to allow curving of a tip assembly  200  in a vertical “up” direction (but not in a vertical “down” direction) against each strand of the midline cable  140  running through said lateral channels  216 . 
       FIG. 5A  is a perspective view of a cavity creator shaft coupler  260  representative of various embodiments disclosed herein.  FIG. 5B  is a side view of the cavity creator shaft coupler  260  of  FIG. 5A . 
     Referring to  FIGS. 5A and 5B  (collectively referred to herein as “FIG.  5 ”), the shaft coupler  260  comprises a partial curving element  222 ′ corresponding to the distal end  262 , a collar  266  centrally located, and an insertion component  268  corresponding to the proximal end  264 . The shaft coupler  260  further comprises two lateral channels  216 , one oriented to each side of the shaft coupler  260 , as well as a top channel  220  oriented to the top of the shaft coupler  260 , where all three channels run from the proximal end  262  to the distal end  264  of the shaft coupler  260 . 
     The partial curving element  222 ′, insertable into the proximal end of the coil enclosure  250 , further comprises a partially-cylindrical concave distal female end  204  for operatively coupling to a corresponding partially-cylindrical proximal male end  202  of a curving element  230  to facilitate curving of the tip assembly  200  in a vertical direction and help prevent curving in a horizontal direction (the partially-cylindrical shape being curved in the vertical direction but flat in the horizontal direction). The collar  266  comprises a first stop surface  272  for engaging but not passing into the distal end of the intra-catheter shaft  300 , as well as a second stop surface  274  for engaging but not passing into the proximal end of the coil enclosure  250 . The insertion component  268 , in turn, is insertable into the distal end of the intra-catheter shaft  300  and, for certain embodiments, may be fastening or welded to said intra-catheter shaft  300 . 
       FIG. 6  is a side view of a cavity creator coil enclosure  250  representative of various embodiments disclosed herein. The coil enclosure  250  is both compressible relative to the longitudinal direction as shown, as well as curvable relative from the longitudinal direction as shown. The proximal end  252  of the coil enclosure  250  operatively couples with the second stop surface  274  of the shaft coupler  260 , and the distal end  254  of the coil enclosure  250  operatively couples with the stop surface  228  of the tip  210 . The helical body  258  of the coil enclosure  250  forms a hollow  256  extending from the distal end  254  to the proximal end  252  of the coil enclosure  250  and effectively encloses the proximal end  212  of the tip  210 , the plurality of interconnecting curving elements  230 , and the distal end  264  of the shaft coupler  260  that comprise the tip assembly  200 . The tip assembly  200 , in turn, couples to the distal end of the intra-catheter shaft  300 , and the midline cable  140  and the off-center cable  120  fixedly coupled to the tip  210  pass through the tip assembly  200  and through the intra-catheter shaft  300  to the lever assembly  400  in the case of the off-center cable  120 , and through the lever assembly  400  and the rotation shaft  500  to the tensioner assembly  600  in the case of both strands of the midline cable  140 . 
       FIG. 7A  is an exploded perspective view of an exemplary lever assembly  400  of an articulated cavity creator  100  representative of several embodiments disclosed herein.  FIG. 7B  is an exposed side view of the exemplary lever assembly  400  of  FIG. 7A  (with the left body  422  of the lever pivot  420  removed). 
     Referring to  FIGS. 7A and 7B  (collectively referred to herein as “FIG.  7 ”), the lever assembly  400  comprises a receiver  410 , a lever pivot  420  (comprising a left body  422  and a right body  424 ) a lever  430 , and a lever spring  440 . Also shown for reference are the proximal end of the intra-catheter shaft  300  and the distal end of the rotation shaft  500 . 
     The distal end of the receiver  410  is coupled to the intra-catheter shaft  300 , while the proximal end of the receiver  410  is coupled to the distal end  448  of the lever pivot  420 . The lever pivot  420  is also movably coupled to the lever  430  via a pivot pin  428  where the pivot pin  428  is coupled at each end to the left body  422  and right body  424  of the lever pivot  420  and passes through the pivot channel  432  of the lever  430  to couple with the lever  430 . In various embodiments, pivot pin  428  may be fixedly coupled to the lever pivot  420 , the lever  430 , or neither (i.e., movably coupled to both). The lever spring  440  comprises a proximal end  442  operatively coupled to a boss  501  of the rotation shaft  500 , and a distal end  444  operatively coupled to a proximal surface  434  of the lever  430 . 
     As further illustrated in  FIG. 7B , the midline cable  140  (one strand visible and the other strand obscured behind the visible strand) passes through the receiver  410 , the lever  430 , and the lever spring  440 . The off-center cable  120  passes through the receiver  410  and is fixedly connected to the lever  430 . In certain embodiments, as illustrated, the off-center cable  120  may be fixedly attached to a threaded coupling rod  122  that then screws through a channel  438  in the lever  430  and is affixed in position with a washer and nut combination  124 . 
     The lever spring  440  exerts pressure against the lever  430  to maintain the lever  430  in a longitudinally forward position (in the distal direction) which, in turn, keeps the tip assembly  200  in an uncurved orientation. However, pressure applied to the pressure surface  436  of the lever  430  causes the lever to pivot longitudinally backward (in the proximal direction) which, in turn, causes the tip assembly  200  to curve about an axis. (The motion of the tip assembly  200  thus carves a narrow path through, for example, cancellous bone.) 
       FIG. 8A  is side view of an exemplary rotation shaft  500  of an articulated cavity creator  100  representative of several embodiments disclosed herein.  FIG. 8B  is a cross-sectional view of the exemplary rotation shaft  500  of  FIG. 8A . 
     Referring to  FIGS. 8A and 8B  (collectively referred to herein as “FIG.  8 ”), the rotation shaft  500  comprises a proximal end  502  for operationally coupling to a tensioner assembly  600  as well as a distal end  504  (e.g., a groove) for fixedly coupling to a lever assembly  400 . The rotation shaft  500  also comprises a central channel  510  through which the midline cable  140  passes. The proximal end  502  further comprises two coupling slots  512  to movably couple the tensioner (not shown) of the tensioner assembly  600  (described in more detail below). The rotation shaft  500  enables an operator (such as a surgeon) to rotate (or “twist”) the entire articulated cavity creator  100  and, in turn, rotate (or “spin”) the tip assembly  200  in a manner that, coupled with the variable curving ability provided by the lever assembly  400 , carves out a cavity within, for example, cancellous bone. 
       FIG. 9  is an exploded perspective view of an exemplary tensioner assembly  600  comprising the proximal end of an articulated cavity creator  100  representative of several embodiments disclosed herein. As illustrated, the tensioner assembly  600  comprises a tensioner  620 , a midline pin  640 , and a tension knob  650 . Also shown for reference is the proximal end  502  of the rotation shaft  500 , said proximal end comprising the two coupling slots  512  to movably couple the tensioner  620 . 
       FIG. 10A  is a perspective view of a cavity creator tensioner  620  representative of various embodiments disclosed herein.  FIG. 10B  is a cross-sectional top view of the cavity creator tensioner  620  of  FIG. 10A .  FIG. 10C  is a partially-cross-sectional side view of the cavity creator tensioner of  FIGS. 10A and 10B .  FIG. 10D  is a distal end view of the cavity creator tensioner of  FIGS. 10A ,  10 B, and  10 C. 
     Referring to  FIGS. 10A ,  10 B,  10 C, and  10 D (collectively referred to herein as “FIG.  10 ”), the tensioner  620  comprises a tension head  622  fixedly coupled to a threaded shaft  632  for engaging the tension knob  650 . The tension head  622  further comprises a pin hole  624 , a cable return cavity  626 , and two slotting edges  628 . The two slotting edges  628  slidably engage the two coupling slots  512  of the rotation shaft  500 , thus preventing rotation of the tensioner  620  within the rotation shaft  500  while also ensuring that the tensioner perfectly rotates along with the rotation shaft  500  when it is rotated. 
     In operation, the proximal end of the doubled-back midline cable  140 , comprising a 180-degree turn in the cable, is inserted into cable return cavity  626  and the midline pin  640  is introduced through the pin hole  624  to hold the midline cable  140  in place (as shown in  FIG. 10D ). In this manner, the midline cable  140 , being movable along the proximal rounded surface of the midline pin  640 , provides even tension throughout the entire device to the tip assembly  200 . 
       FIG. 11A  is a perspective view of a cavity creator tension knob  650  representative of various embodiments disclosed herein.  FIG. 11B  is a side view of the cavity creator tension knob  650  of  FIG. 11A .  FIG. 11C  is a cross-sectional side view of the cavity creator tension knob  650  of  FIGS. 11A and 11B .  FIG. 11D  is a proximal end view of the cavity creator tension knob  650  of  FIGS. 11A ,  11 B, and  11 C. 
     Referring to  FIGS. 11A ,  11 B,  11 C, and  11 D (collectively referred to herein as “FIG.  11 ”), the tension knob  650  comprises a twist body  652  having a proximal end  654  and a distal end  656  and a threaded hole  658  running from the proximal end  654  to the distal end  656 . The distal end  656  abuts against the proximal end  502  of the rotation shaft  500  but is still able to rotate. The threaded hole  658  engages the threaded shaft  632  of the tensioner  620  enabling the tension knob  650  to draw the tensioner  620  back in a proximal direction by rotably turning the tension knob  650  in one direction (e.g. clockwise) and thereby increase the tension on the midline wire  140 . Conversely, by rotably turning the tension knob  650  in the opposite direction (e.g., counterclockwise), the threaded shaft  632  of the tensioner  620  is pushed forward in the distal direction and decreases tension on the midline wire  140 . 
       FIG. 12A  is a perspective view of a maximum cavity  702  creatable utilizing certain embodiments of the articulated cavity creator  100  disclosed herein.  FIG. 12B  is a side view of the maximum cavity of  FIG. 12A  further including the tip assembly  200  of  FIG. 2  in position within the interior body.  FIG. 12C  is an operational flow diagram illustrating a method  740  for creating the cavity illustrated in  FIGS. 12A and 12B  utilizing certain embodiments of the cavity creator disclosed herein. 
     Referring to  FIGS. 12A ,  12 B, and  12 C (collectively referred to herein as “FIG.  12 ”), the method  740  comprises, at  742 , inserting a catheter into a target location such as an interior body (e.g., a region of cancellous bone). At  744 , inserting the articulated cavity creator  100  through the catheter such that the tip assembly  100  extends beyond the distal end of the catheter and into the target region. At  746 , the tip assembly  200  is curved and straightened by action of the lever  430  in combination with the articulated cavity creator  100  being rotated via the rotation shaft  500 . For example, in one approach, the tip assembly  100  might be incrementally curved through its range of motion (from straight to maximally curved), moving the tip  210  no more than its width with each increment, and at each increment rotating the rotation shaft  500  at least a full 360-degrees. In another approach, the rotation shaft might be rotated incrementally through a full rotation (360-degrees), rotating the tip  210  with each increment no more than the tip&#39;s  210  width in each increment position (such as when curved perpendicular to the intra-catheter shaft  300 ), and at each increment engaging the lever  430  to move the tip assembly  200  through its full range of motion from straight to maximally curved and back. At  738 , the articulated cavity creator  100  is removed. 
     It should be noted that specific features of the various embodiments disclosed herein can be performed manually by user-applied forces or, alternately, utilizing specialized motors. For example, the rotation and curving of the device to form a cavity can be performed manually by a surgeon who rotates the device via the rotation shaft and also curves the device by action of the lever assembly. Conversely, the rotation and/or the curving of the tip assembly can be performed by motorized components that may utilize, in certain implementations, microprocessors or other guidance systems to coordinate the rotation and curving motions to optimally form the cavity within the target body. 
     As will be readily appreciated by those of skill in the art, the various components described herein can be formed from a variety of biocompatible materials, such as cobalt chromium molybdenum (CoCrMo), titanium and titanium alloys, stainless steel or other metals, as well as ceramics or polymers. A coating may be added or applied to the various components described herein to improve physical or chemical properties, such as a plasma-sprayed titanium coating or Hydroxypatite. Moreover, skilled artisans will also appreciate that the various components herein described can be constructed with any dimensions desirable for implantation and cavity creation. 
     In addition, the various embodiments disclosed herein may be adapted for use in virtually any interior body region where the formation of a cavity within tissue is required for a therapeutic or diagnostic purpose. While several embodiments are herein described with regard to treating bones, other embodiments can be used in other interior body regions as well. In addition, it is also anticipated that certain embodiments could be used for purposes other than medical, such as construction, manufacturing, and excavation, among others; accordingly, nothing herein is intended to limit application of the various embodiments to purely medical uses. 
     Accordingly, 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.