Abstract:
A balloon catheter can include an actively steerable element for adjusting the configuration of the balloon after placement at a target location. By coupling the actively steerable element to the balloon, any articulation of the actively steerable element will also re-configure the position of the balloon, thereby enabling greater control over procedures that make use of such a balloon catheter. The active steering capability can also enhance the material manipulation capabilities of the balloon catheter, and enable operations and actions that are not possible with a non-steerable balloon catheter.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a system and method for performing a surgical procedure, and in particular, to an articulating balloon catheter. 
       BACKGROUND OF THE INVENTION 
       [0002]    A minimally invasive procedure is a medical procedure that is performed through the skin or an anatomical opening. In contrast to an open procedure for the same purpose, a minimally invasive procedure will generally be less traumatic to the patient and result in a reduced recovery period. 
         [0003]    However, there are numerous challenges that minimally invasive procedures present. For example, minimally invasive procedures are typically more time-consuming than their open procedure analogues due to the challenges of working within a constrained operative pathway. In addition, without direct visual feedback into the operative location, accurately selecting, sizing, placing, and/or applying minimally invasive surgical instruments and/or treatment materials/devices can be difficult. 
         [0004]    For example, for many individuals in our aging world population, undiagnosed and/or untreatable bone strength losses have weakened these individuals&#39; bones to a point that even normal daily activities pose a significant threat of fracture. In one common scenario, when the bones of the spine are sufficiently weakened, the compressive forces in the spine can cause fracture and/or deformation of the vertebral bodies. For sufficiently weakened bone, even normal daily activities like walking down steps or carrying groceries can cause a collapse of one or more spinal bones. A fracture of the vertebral body in this manner is typically referred to as a vertebral compression fracture. Other commonly occurring fractures resulting from weakened bones can include hip, wrist, knee and ankle fractures, to name a few. 
         [0005]    Fractures such as vertebral compression fractures often result in episodes of pain that are chronic and intense. Aside from the pain caused by the fracture itself, the involvement of the spinal column can result in pinched and/or damaged nerves, causing paralysis, loss of function, and intense pain which radiates throughout the patient&#39;s body. Even where nerves are not affected, however, the intense pain associated with all types of fractures is debilitating, resulting in a great deal of stress, impaired mobility and other long-term consequences. For example, progressive spinal fractures can, over time, cause serious deformation of the spine (“kyphosis”), giving an individual a hunched-back appearance, and can also result in significantly reduced lung capacity and increased mortality. 
         [0006]    Because patients with these problems are typically older, and often suffer from various other significant health complications, many of these individuals are unable to tolerate invasive surgery. Therefore, in an effort to more effectively and directly treat vertebral compression fractures, minimally invasive techniques such as vertebroplasty and, subsequently, kyphoplasty, have been developed. Vertebroplasty involves the injection of a flowable reinforcing material, usually polymethylmethacrylate (PMMA—commonly known as bone cement), into a fractured, weakened, or diseased vertebral body. Shortly after injection, the liquid filling material hardens or polymerizes, desirably supporting the vertebral body internally, alleviating pain and preventing further collapse of the injected vertebral body. 
         [0007]    Because the liquid bone cement naturally follows the path of least resistance within bone, and because the small-diameter needles used to deliver bone cement in vertebroplasty procedure require either high delivery pressures and/or less viscous bone cements, ensuring that the bone cement remains within the already compromised vertebral body is a significant concern in vertebroplasty procedures. Kyphoplasty addresses this issue by first creating a cavity within the vertebral body (e.g., with an inflatable balloon) and then filling that cavity with bone filler material. The cavity provides a natural containment region that minimizes the risk of bone filler material escape from the vertebral body. An additional benefit of kyphoplasty is that the creation of the cavity can also restore the original height of the vertebral body, further enhancing the benefit of the procedure. 
         [0008]    Conventional kyphoplasty systems use balloon catheters that can be inflated to a desired size by the physician. Inflation is performed once the balloon catheters are placed within the bone (typically using a transpedicular approach). Therefore, the final positioning and configuration of the actual balloons is defined solely by the placement of the balloon catheter. However, in some instances, the as-placed position of the balloon may not be optimal for the procedure (e.g., configuring the balloon such that inflation occurs towards the anterior of the vertebral body can enhance the mechanical advantage provided by the balloon during inflation). Unfortunately, conventional balloon catheters do not allow such “post-placement” repositioning of the balloon. 
         [0009]    Accordingly, it is desirable to provide surgical tools and techniques that enable adjustment of placement in-situ. 
       SUMMARY OF THE INVENTION 
       [0010]    By incorporating an actively steerable element into a balloon catheter, repositioning of the balloon can be beneficially performed after the balloon catheter has been inserted into the target surgical location. 
         [0011]    In one embodiment, a balloon catheter can include an elongate shaft coupled to a balloon, a steering mechanism extending along the shaft and positioning a steerable element into or adjacent the balloon, and an actuator for articulating the steerable element. In various embodiments, the steering mechanism can be positioned within the elongate shaft, and can optionally be placed within an inner catheter within the elongate shaft. In various other embodiments, the steering mechanism can be positioned adjacent to the elongate shaft. 
         [0012]    Manipulation of the actuator articulates the steerable element such that the configuration of the balloon is changes. In doing so, the positioning/placement of the balloon during a surgical procedure can be adjusted as desired by the physician to achieve a desired outcome. 
         [0013]    In various embodiments, an actively steerable balloon catheter can be used in a kyphoplasty procedure to allow adjustment the positioning and/or placement of the balloon within the vertebral body. In so doing, the procedure can be performed using a unilateral approach while still providing proper bone filler material placement for good structural support. However, in other embodiments, the actively steerable balloon catheter can be used in conventional bilateral procedures, or other surgical procedures. 
         [0014]    As will be realized by those of skilled in the art, many different embodiments of an balloon catheter incorporating active steering capabilities, along with systems, kits, and/or methods of using such a balloon catheter according to the present invention are possible. Additional uses, advantages, and features of the invention are set forth in the illustrative embodiments discussed in the detailed description herein and will become more apparent to those skilled in the art upon examination of the following. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIGS. 1A-1B  show an exemplary balloon catheter that incorporates a steering element for in-situ balloon positioning. 
           [0016]      FIGS. 2A-2B  show an exemplary steering element for use in a balloon catheter. 
           [0017]      FIG. 3  shows a kit that includes a balloon catheter that incorporates a steering element for in-situ balloon positioning. 
           [0018]      FIGS. 4A-4F  show an exemplary kyphoplasty procedure using an expandable bone tamp incorporating a steering element for in-situ balloon positioning. 
           [0019]      FIG. 5  shows a flow diagram for performing a surgical procedure using an in-situ steerable balloon catheter. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    By incorporating an actively steerable element into a balloon catheter, repositioning of the balloon can be beneficially performed after the balloon catheter has been inserted into the target surgical location. 
         [0021]      FIG. 1A  shows a cross-section of an embodiment of a balloon catheter  100  that can be used in a surgical procedure, such as balloon kyphoplasty. Balloon catheter  100  includes a shaft  110 , an inflatable structure (e.g., balloon)  120 , a steering mechanism  130 , an actuator  140  for controlling steering mechanism  130 , and a connector  150 . Inflatable structure  120  can be formed from a compliant (e.g., latex), semi-compliant (e.g., polyurethane), or non-compliant (e.g., nylon) material. Although depicted as a single-chamber “peanut”-shaped balloon for exemplary purposes, balloon  120  can have any shape and/or construction (e.g., a spherical balloon, a multi-chamber balloon, or a balloon with internal or external shaping/reinforcing features, among others). 
         [0022]    Inflatable structure  120  is coupled to a distal end  110 -D of shaft  110 , and connector  150  is coupled to a proximal end  110 -P of shaft  110 . Connector  150  includes a port  150 A (e.g., a Luer lock connection) for receiving inflation material (e.g., saline solution or contrast solution) for inflating balloon  120 . Note that in various embodiments, connector  150  can include any number of any type of ports. 
         [0023]    Steering mechanism  130  includes a steerable element  132  and a shaft  131  that couples steerable element  132  to actuator  140 . Steerable element  132  can be configured into a variety of shapes (i.e., articulated) by actuator  140  without any external restraint, and is therefore “actively” steerable (in contrast to a passive structure like a bent shape-memory wire that can only be straightened by being placed in an external sleeve or sheath). 
         [0024]    Note also that minimally invasive procedures such as kyphoplasty are typically performed under fluoroscopy, so that the physician can at least have some visual indication of the surgical activity within the patient. Therefore, in some embodiments, optional radiopaque markers  132 M can be placed at various locations on steerable element  132  to facilitate positioning of balloon catheter  100  in the patient. In various other embodiments, steerable element  132  can be formed from, or can include, radiopaque material(s). 
         [0025]    Because steerable element  132  extends into balloon  120  such that reconfiguration of steerable element  132  by actuator  140  (e.g., as shown in  FIG. 1B ) also changes the shape of balloon  120 . In various embodiments, steerable element can be coupled to a distal end  120 -D of balloon  120  (or any other location on the inside or outside of balloon  120 ). In various other embodiments, balloon catheter  100  can include an optional inner catheter  111  within shaft  110 , with the distal end of inner catheter  111  being coupled to the distal end  120 -D of balloon  120 . Steerable element  132  could then be positioned within, or outside of, inner catheter  111  within balloon  120  to provide steering control over balloon  120 . In various other embodiments, inner catheter  111  could accept a stiffening stylet or guidewire (not shown for simplicity), with steering mechanism  130  either sharing the space within inner catheter  111  or being positioned outside of inner catheter  111 . Finally, in various other embodiments, steerable element  132  can simply extend into balloon  120  with its distal end  132 -D completely unattached. 
         [0026]      FIGS. 2A and 2B  show an exemplary embodiment of steering mechanism  130 , in which steerable element  132  includes a series of slots  132 S formed in shaft  131 . A cable  132 C is attached to the distal end  132 -D of steerable element  132  and runs slidably through shaft  131  to actuator  140 . Actuator  140  includes a spindle  142  mounted on a thumbwheel  141 , with cable  132 C attached to spindle  142 . 
         [0027]    Rotating thumbwheel  141  as shown in  FIG. 2B  winds cable  132 C around spindle  142 , thereby causing slotted steerable element  132  to curl away from the longitudinal axis of shaft  131 . Slots  132 S determine the direction of curvature for steerable element  132 . In one embodiment, shaft  131  includes features  131 F (e.g., flanges, a collar, ribs, or extensions, among others) that facilitate rotation of steering mechanism (in various other embodiments, such features can be placed elsewhere on balloon catheter  100 ). 
         [0028]    In various embodiments, shaft  131  can be formed from shape-memory material (e.g., Nitinol) so that once cable  132 C is allowed to unspool from spindle  142  (e.g., by releasing or unlocking thumbwheel  141 ), steerable element  132  returns to its original (straight) configuration. In various other embodiments, cable  132 C can be selected to have sufficient axial rigidity to “push” steerable element  132  back into a straight configuration. In various other embodiments, steering mechanism  130  can include multiple cables to control the configuration of steerable element  132 . For example, in one embodiment, steering mechanism  130  can include a second cable in opposition to cable  132 S to flex steerable element  132  back to a straight condition (or even to curve in a different direction). 
         [0029]    Note that while steering mechanism  130  is depicted as having steerable element  132  formed as a slotted shaft for exemplary purposes, steerable element  132  can have any construction that provides active steering capability at steerable element  132 . For example, in various embodiments, steerable element  132  could include a flexible sleeve over a flexible internal member between parallel control cables, such that each cable pulls the flexible member in a different direction. In various other embodiments, steerable element  132  could include a coil of wire surrounding a relatively rigid core that pushes distally to flex the coil. Various other embodiments will be readily apparent. 
         [0030]      FIG. 3  shows a diagram of a kit  300  for use in performing a surgical procedure (e.g., balloon kyphoplasty) as described in greater detail below. Kit  300  includes a balloon catheter  100  that includes an actively steerable element  132  (e.g., as described above with respect to  FIGS. 1A-1B ,  2 A- 2 B). In various embodiments, kit  300  can further include optional additional instruments  301 , such as a cannula  304  sized to receive balloon catheter  100 , an introducer, guide pin, drill, curette, and/or access needle, among others (only cannula  404  is shown for simplicity). In various other embodiments, kit  300  can further include optional directions for use  302  that provide instructions for using balloon catheter  100  and optional additional instruments  301  (e.g., instructions for performing a balloon kyphoplasty procedure using balloon catheter  100  and optional additional instruments  301 ). 
         [0031]      FIGS. 4A-4F  show an exemplary kyphoplasty procedure using a balloon catheter  100  that incorporates an actively steerable element  132  (as described with respect to  FIGS. 1A-1B ). Note that while a unilateral procedure (i.e., use of a single balloon catheter) is depicted for exemplary purposes, in various other embodiments any number of balloon catheters  100  can be used. In some embodiments, actively steerable balloon catheter  100  can be used with conventional (i.e., not actively steerable) balloon catheters. 
         [0032]      FIG. 4A  shows cross-sectional transverse view of a portion of a human vertebral column having a vertebra  400 . Vertebra  400  has collapsed due to a vertebral compression fracture (VCF) that could be the result of osteoporosis, cancer-related weakening of the bone, and/or physical trauma. The resulting abnormal curvature of the spine caused by such a fracture can lead to severe pain and further fracturing of adjacent vertebral bodies. 
         [0033]    In  FIG. 4A , a cannula  410  is positioned within fractured vertebra  400 , thereby providing an access path to the target surgical location, which in this case is the cancellous bone structure  400 -C within vertebra  400 . Typically, cannula  410  would be docked into the exterior wall of vertebral body  400  (via either a transpedicular or extrapedicular approach) using a guide needle and/or dissector, after which a drill or other access tool (not shown) could be used to create a path further into cancellous bone  400 -C. However, any other method of cannula placement can be used. Balloon catheter  100  is inserted into cannula  410  to position balloon  120  within cancellous bone  400 -C. 
         [0034]    Then, as shown in  FIG. 4B , actuator  140  is used to change the configuration of steerable element  132 , in this example causing steerable element  132  to curve inward and away from the exterior wall of vertebral body  400 . Consequently, balloon  120  is similarly repositioned by steerable element  132 . 
         [0035]    In some embodiments, a curette or other mechanical tool can be used to break up or scrape away a portion of cancellous bone  400 -C prior to the insertion of balloon catheter  100  into vertebral body  400 . In this manner, the resistance encountered by steerable element  132  as it moves within vertebral body  400  can be minimized. 
         [0036]    However, besides providing greater positional control over balloon  120 , the active steering functionality of steerable element  132  can also provide force generation capabilities that are significantly greater than would be possible from passive shaping elements (e.g., a wire with a preformed bend positioned within balloon  120 ). Therefore, in various embodiments, balloon catheter  100  itself can be used to scrape, cut, and/or compact cancellous bone  400 -C through the articulation of steerable element  132 . 
         [0037]    Note that while the placement and positioning of balloon  120  is described as a sequential two-step process (i.e., insert balloon catheter  100  into vertebra  300  and then articulate steerable element  132 ) for exemplary purposes, any number and sequence of placement and positioning steps can be performed. For example, in one embodiment, balloon  120  could be placed in cancellous bone, steerable element  132  could be articulated, balloon catheter  100  could be moved further into cannula  410 , and steerable element  132  could be articulated again. In various other embodiments, balloon catheter  100  could be moved further inward or outward relative to cannula  410  concurrently with the articulation of steerable element  132 . 
         [0038]    One balloon  120  is positioned as desired by steerable element  132 , balloon  120  can be inflated as shown in  FIG. 4C . This inflation can be performed by injecting an inflation fluid P (e.g., saline solution or contrast solution, among others) through connector  150 . Then, when balloon  120  is deflated (inflation fluid P removed) as shown in  FIG. 4D , a well-defined cavity  425  remains within cancellous bone  400 -C. 
         [0039]    Balloon catheter  100  can then be removed from vertebral body  400  by straightening steerable element  132  using actuator  140 , or by simply allowing balloon  120  and steerable element  132  to be straightened as they are pulled through cannula  410 , or by a combination of both. 
         [0040]    Then, as shown in  FIG. 4E , cavity  450  is filled with bone filler material  460  (e.g., PMMA) delivered by a nozzle  450  inserted through cannula  410 . Bone filler material  460  can be expressed from nozzle  450  by any type of material delivery system, such as a syringe, plunger, and/or a hydraulic system among others. Note that while a nozzle having a side port is depicted for exemplary purposes, in various other embodiments, any type of delivery nozzle can be used (e.g., a open-ended nozzle or a multi-port nozzle, among others). 
         [0041]    Once the filling operation is complete, delivery nozzle  450  and cannula  410  are removed from vertebra  400  (and the patient&#39;s body) as shown in  FIG. 4F . Upon hardening, bone filler material  460  provides structural support for vertebra  400 , thereby substantially restoring the structural integrity of the bone and the proper musculoskeletal alignment of the spine. Note that steerable element  132  of balloon catheter  100  allows bone filler material  460  to be delivered to a structurally advantageous location (e.g., towards the medial region of vertebral body  400 ) using a unilateral approach. This can beneficially reduce patient trauma compared to a typical bilateral kyphoplasty procedure while still providing the desired outcome. 
         [0042]      FIG. 5  shows a flow diagram of a process for performing a surgical procedure such as kyphoplasty using a balloon catheter incorporating an actively steerable element (as described with respect to  FIGS. 1A-1B ). In a PLACE CANNULA(S) step  510 , one or more cannulas is positioned within a patient to provide a path to a target surgical location (e.g., as described with respect to  FIG. 4A ). 
         [0043]    Then, in an INSERT STEERABLE BALLON CATHETER(S) step  520 , one or more balloon catheters with an actively steerable element (e.g., as described with respect to  FIGS. 1A-1B ) is placed within the patient through the cannula(s) (e.g., as described with respect to  FIG. 4A ). 
         [0044]    Next, in an ARTICULATE BALLOON CATHETER(S) IN-SITU step  530 , the steerable element in each steerable balloon catheter can articulated to reposition the balloon catheter balloon (e.g., as described with respect to  FIG. 4B ). The balloon catheter(s) is (are) then inflated (e.g., as described with respect to  FIG. 4C ) in an INFLATE BALLOON CATHETER(S) step  540 , with the steerable element at least partially controlling the inflation profile of the balloon. Note that in various embodiments, steps  530  and  540  can be performed any number of times, and in various orders, including simultaneously. 
         [0045]    Then, in REMOVE BALLOON CATHETER(S) step  550 , the balloon(s) are deflated and removed from the patient (e.g., as described with respect to  FIG. 4D ). Note that in some embodiments, steerable element can be articulated during this operation to simplify the removal process. 
         [0046]    Finally, in a PERFORM ADDITIONAL SURGICAL OPERATIONS step  560 , operations not involving the balloon catheter(s) can be performed to complete the procedure. For example, after removal of the balloon catheter from a bone, filler material can be delivered to the cavity formed by the balloon catheter (e.g., as described with respect to  FIGS. 4E-4F ). 
         [0047]    Note that although the use of a balloon catheter incorporating an actively steerable steering element is described herein with respect to a kyphoplasty procedure for exemplary purposes, in various other embodiments, the steerable balloon catheter can be used in any other procedure that would benefit from such articulating capabilities. 
         [0048]    For example, in some embodiments, a balloon catheter could be used to treat a long bone fracture. The steerable element could then allow the balloon to be optimally aligned in the long bone regardless of the particular access path used to initially place the balloon within the bone. 
         [0049]    In various other embodiments, a steerable balloon catheter could be used to assess the open space within a vertebral disc. To treat back pain, a spinal fusion procedure is sometimes performed in which adjacent vertebrae are fused together. As part of the procedure, a portion of the intermediate disc nucleus material is removed for placement of an implant to assist the fusion. A balloon catheter with steerable element could be used immediately after the nucleus removal operation to determine the size and/or shape of the resulting nuclear space, with the steerability of the balloon catheter enabling optimized positioning for this diagnostic operation. Various other procedures that could benefit from an actively steerable balloon catheter will be readily apparent. 
         [0050]    While various embodiments of the invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art having the benefit of this disclosure would recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the invention. Additionally, certain steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. Thus, the breadth and scope of the invention should not be limited by any of the above-described embodiments, but should be defined only in accordance with the following claims and their equivalents. While the invention has been particularly shown and described with reference to specific embodiments thereof, it will be understood that various changes in form and details may be made.