Abstract:
An apparatus is disclosed for introducing surgical instruments into a body cavity. The apparatus includes a series of interconnected segments configured to pivot relative to one another allowing an end effector to be steered into position. The apparatus is also capable of achieving a rigidized state wherein the interconnected segments are in high frictional contact with one another providing a stable platform for the manipulation of tissue. Tensile elements are attached to the end effector and a control member such that an operator may use the same control member to both rigidize the instrument and also to thereafter control the end effector.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of and priority to U.S. Provisional Patent Application No. 61/031,374, filed Feb. 26, 2008, the entire disclosure of which is incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates generally to flexible steerable instruments, such as steerable catheters and/or probes which are remotely operated in endoscopic, endoluminal and laparoscopic procedures. In particular, the disclosure relates to a system and related methods for rigidizing a flexible steerable instrument and manipulating a distal tool on the rigidized instrument. 
         [0004]    2. Background of Related Art 
         [0005]    Surgical procedures such as laparoscopic, arthroscopic, and endoscopic procedures in general are termed minimally invasive at least in part because the incision required is relatively small, perhaps one inch in length or less. Small incisions are preferred because they are inherently less traumatic to the body tissue and subject internal organs to only a minimum of exposure to the contaminants in the outside atmosphere. Thus, small incisions enable shorter hospital stays and faster recoveries with less pain and scarring than is common with the larger incisions required for conventional surgery. 
         [0006]    Endoscopic surgery is possible due in part to the availability of instruments designed specifically for this purpose. One such type of instrument, which may also be used for endoluminal procedures, is a flexible steerable instrument which may have a tool assembly (e.g., grasping jaws, cutting tools, camera, suction attachment, etc.) attached at the distal end. These instruments may be navigated and steered inside the patient&#39;s body using controls disposed on a proximal end of the instrument as the instrument is advanced into a body cavity such as the patient&#39;s bowel. Once in position, it is often desirable to maintain the particular position achieved by the instrument to facilitate tissue manipulation using the tool assembly. 
         [0007]    Conventional flexible steerable instruments include two or more segments configured to pivot and/or swivel relative to each other. One or more tensile elements are coupled to the distal segment to allow the segments to be drawn into high frictional contact with one another thereby rigidizing the instrument. One drawback of the conventional flexible steerable instruments is that once rigidized the tensile elements are ineffective for controlling the distal tool. Any further manipulation of the tensile elements tends to alter the position achieved by the instrument. Therefore, to control the tool additional components must be incorporated increasing the cost, complexity and even the overall size of the instrument, which for example, can detract from the attendant advantages of endoscopic surgery. Accordingly, a need exists for a carrier apparatus including tensile elements adapted to both rigidize the apparatus and also to manipulate a surgical tool. 
       SUMMARY 
       [0008]    The present disclosure describes a surgical apparatus for insertion into a body cavity. The apparatus includes an elongated flexibly body with an end effector disposed at a distal end of the body and a control member at a proximal end of the body. At least one pair of tensile elements is connected to the end effector such that a general tension applied to the pair of tensile elements tends to shift the instrument from a flexible condition to a rigid condition, while a differential tension applied to the pair of tensile elements tends to cause motion in the end effector. The motion in the end effector may be used to steer the apparatus into position and to manipulate tissue. 
         [0009]    In some embodiments the elongated body may include a series of interconnected segments adapted to pivot relative to one another to give the instrument flexibility at least at a distal portion of the instrument. The segments may assume a substantially spherical shape with a concave surface on one end which interfaces with a convex surface on a neighboring segment. Each segment may include a cavity or throughbore which in combination with the cavities and throughbores in the remaining segments forms a central channel through all the segments. The segments may be forced into a high frictional contact by a general tension in the tensile elements to rigidize the apparatus. The general tension may be transmitted through the end effector and a support member connected to a leading segment to cause the high frictional contact that rigidizes the apparatus. The control member and the end effector may include a bell crank, which is connected to the tensile elements such that a pivotal movement of one bell crank effects corresponding pivotal movement in the other bell crank. 
         [0010]    A method of operation is also disclosed. The distal end of an instrument may be inserted into a body cavity of a patient. An operator may steer the distal end of the instrument into a body lumen using a control member, rigidize a portion of the instrument, and thereafter manipulate the distal end of the instrument using the same control member used to steer the instrument into position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the detailed description of the embodiments given below, serve to explain the principles of the disclosure. 
           [0012]      FIG. 1A  is a perspective view of a flexible steerable instrument according to one illustrative embodiment of the disclosure; 
           [0013]      FIG. 1B  is a bottom partial-cross sectional view of a proximal portion of the flexible steerable instrument shown in  FIG. 1A  further depicting a handle; 
           [0014]      FIG. 1C  is a view similar to  FIG. 1B  depicting the proximal bell crank moved to an alternate position with respect to the handle; 
           [0015]      FIG. 2  is a top partial-cross-sectional view of the flexible steerable instrument shown in  FIG. 1A  depicting the instrument in a relaxed condition; 
           [0016]      FIG. 3  is an enlarged view of the area of detail identified in  FIG. 2 ; 
           [0017]      FIG. 4  is a partial perspective view with parts separated of a central portion of the flexible steerable instrument shown in  FIG. 1A  depicting interfacing surfaces of the instrument; 
           [0018]      FIG. 5  is a view similar to  FIG. 2  depicting the instrument in a relaxed condition and biased to the right with respect to an operator; 
           [0019]      FIG. 6  is a view similar to  FIG. 2  depicting the instrument in a relaxed condition and articulated to the left with respect to an operator; 
           [0020]      FIG. 7  is a view similar to  FIG. 2  depicting the instrument in a rigid condition and articulated to the left with respect to an operator; and 
           [0021]      FIG. 8  is an enlarged view of the area of detail identified in  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0022]    Embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. In the drawings and in the description that follows, the term “proximal,” as is traditional, will refer to the direction toward the operator or a relative position on the surgical device or instrument that is closer to the operator, while the term “distal” will refer to the direction away from the operator or relative position of the instrument that is further from the operator. 
         [0023]    Referring initially to  FIG. 1A , a flexible steerable apparatus  10  includes an elongated flexible carrier body  12  comprising a plurality of interconnected segments  14  including a leading segment  16  and a trailing segment  18 . Each segment  14  is configured to pivot relative to neighboring segments  14  allowing the apparatus to assume a linear configuration ( FIG. 2 ), a serpentine path ( FIG. 1A ) or any configuration therebetween. A support member  20  is fixedly attached between the leading segment  16  and a distal bell crank  22  such that no relative motion between these components is readily achieved. In other embodiments, the support member  20  may be allowed to pivot with respect to the leading segment  16 . An end effector  23 , which may be supported on or by of formed integrally with distal bell crank  22  is located at a distal end of the apparatus. End effector  23  may include a variety of implements such as grasping jaws, cutting tools, camera, suction attachments etc. Distal bell crank  22  is pivotally attached to support member  20  such that pivotal motion of bell crank  22  about independent pivot  24  may be achieved as indicated by the arrows marked “A.” Generally, a bell crank is a mechanism characterized for changing motion about a 90 degree angle. Here, distal bell crank  22  assumes a general T-shape. Alternatively, other configurations are envisioned. 
         [0024]    Tensile elements such as tensile members  26 ,  28  are pivotally attached at one end to distal bell crank  22  at attachment points  30  which are substantially spaced radially outwardly of independent pivot  24 . Tensile members  26 ,  28  are slidably disposed through bores  32  in each of the segments  14 . An opposite end of each tensile member  26 ,  28  is pivotally attached to a control member, which may include a proximal bell crank  34 , at attachment points  36 . Tensile members  26 ,  28  may be formed from wires which are substantially inelastic, or alternatively, an elastic material may be used to bias segments  14  into a light contact with one another. 
         [0025]    Proximal bell crank  34  is configured to pivot about independent pivot  38  as indicated by arrows marked “B.” Proximal bell crank  34  is also configured for longitudinal motion with respect to trailing segment  18  as indicated by arrow “C.” Some type of connecting member, may be incorporated to connect the trailing segment  18  to the proximal bell crank  34  that allows the proximal bell crank  34  to slide in the direction of arrow “C” thereby separating the proximal bell crank  34  from the trailing segment  18 . The connecting mechanism may include an elongated component which supports the proximal bell crank  34  at a position spaced from the trailing segment  18  and allows the proximal bell crank  34  to pivot and move axially in relation to the elongated component. For example, a suitable connecting member may include a handle  35  having a slot  37  as depicted in  FIG. 1B . Handle  35  allows for proximal bell crank to move, for example, in the directions of arrows “B” and “C” to assume to position depicted in  FIG. 1C . 
         [0026]    Now with reference to  FIGS. 2 and 3 , steerable instrument  10  is shown in partial cross section to reveal further characteristics. As shown, segments  14  are arranged in a linear fashion such that steerable instrument  10  assumes a straight path. A space  40  between each segment  14  indicates that the tensile members  26 ,  28  are in limited tension and carrier body  12  is in a flexible state where the segments  14  may pivot relative to one another. Each segment  14  includes a central through bore  42 . In combination, the through bores  42  define a central channel  44  through the carrier body  12 . Central channel  44  may provide a conduit through which various devices such as, for example camera equipment may be passed. 
         [0027]    As best seen in  FIG. 4 , each segment  14  has a generally spherical shape with a concave surface  46  on its proximal side and a convex surface  48  on its distal side. The segments  14  mechanically interface with one another by mating the concave surface  46  of one segment with the convex surface  48  of the immediately proximal segment  14 . This allows the segments  14  to pivot with respect to each other in a ball-joint fashion. In other embodiments, the segments  14  may have, for example, a generally cylindrical shape with the concave and convex surfaces  46 ,  48  retained on the proximal and distal ends to allow for ball-joint mating. The segments  14  may be formed from medical grade materials such as stainless steel, thermoplastics, titanium or the like. 
         [0028]    Now with reference to  FIGS. 5 through 8  the operation of steerable apparatus  10  will be described. The apparatus may be advanced into a body cavity such as the bowel of a patient in a distal direction such that the distal bell crank  22  with a tool supported on or formed integrally therewith is disposed within the body cavity. The proximal bell crank  34  remains outside the patient where it may be handled by an operator such as a clinician. The clinician may impart a force on proximal bell crank  34  as indicated by arrow “D” in  FIG. 5 . This causes the proximal bell crank  34  to pivot about independent pivot  38  drawing tensile member  26  in a proximal direction thus increasing the tension in tensile member  26  while relaxing the tension in tensile member  28 . The resulting differential tension in tensile members  26 ,  28  causes the flexible carrier body  12  to curve in the direction of the greater tension as the segments  14  pivot relative to one another. Also, this differential tension causes distal bell crank  22  to pivot about independent pivot  24  as represented by arrow “E.” Likewise, the clinician may impart a force on proximal bell crank  34  in the direction of arrow “F” ( FIG. 6 ) to cause the flexible carrier body  12  to curve in the opposite direction and the distal bell crank  22  to pivot in the direction of arrow “G” ( FIG. 6 ). In this way, the clinician may steer the apparatus  10  as it is advanced through the body cavity to a satisfactory position. 
         [0029]    Once the apparatus  10  has achieved a satisfactory position, the clinician may rigidize the carrier body  12 , i.e. increase the friction between segments  14  to maintain the position and configuration of the carrier body  12 , by imparting a force on the proximal bell crank  34  in the direction of arrow “H” depicted in  FIG. 7 . This causes the proximal bell crank  34  to move in a proximal direction with respect to trailing segment  18 . This motion is first carried through tensile members  26 ,  28 , establishing a general tension therein, to distal bell crank  22 , and then on to support member  20 , on to leading segment  16  and finally on to each successive segment  14  until trailing segment  18  which remains in place. Again, trailing segment  18  is held in place due to a connection mechanism (not shown). This relative motion causes the segments  14  to converge in the direction indicated by arrows “J” as each is drawn toward trailing segment  18 . This convergence creates high frictional forces between the interfacing concave  46  and convex  48  surfaces of segments  14  that rigidize the carrier body  12 . In this rigidized condition, the carrier body  12  will maintain its position and configuration providing a relatively stable platform for the manipulation of tissue. The stabilization allows for greater forces to be developed for pushing, pulling, twisting or general manipulation of targeted tissue. 
         [0030]    Once the apparatus  10  has achieved a rigidized condition, the proximal bell crank  34  may be further pivoted in either direction to cause a corresponding pivot in the distal bell crank  22 . Because the distal bell crank  22  is not subject to the high frictional forces associated with the segments  14 , it will be free to pivot upon an application of a differential tension in tensile members  26 ,  28 . The general tension in tensile members  26 ,  28  that causes the carrier body  12  to assume a rigid condition is defined by the position of proximal bell crank  34  in the direction of arrow “C” ( FIG. 1A ) or “H” ( FIG. 7 ). This general tension is not substantially diminished when, for example, a differential tension is applied by pivoting the proximal bell crank  34 . In this way, an operator may manipulate an end effector of an instrument in a rigid condition using the same control member in the same manner as in steering the instrument into position when in a flexible condition. 
         [0031]    Other embodiments are envisioned in which multiple pairs of tensile elements similar to tensile members  26 ,  28  may be used to both rigidize the carrier body  12  and manipulate an end effector or distal tool. For example, a second pair of tensile elements (not shown) may be placed at a 90 degree angle from tensile members  26 ,  28  to establish an X-Y or multiple-degree-of-freedom steering system when attached to the end effector. A second pivot may be substantially orthogonal to pivot  24  to accommodate such a steering system. Yet another pair of tensile elements could cause a rotation at the distal end. Also, additional tensile members (not shown) may be incorporated to operate end effectors such as graspers, scissors, biopsy pincers and the like. Furthermore, these conventional types of end effectors may be coupled to an end effector such as distal bell crank  22  to allow some degree of motion once the apparatus has achieved a rigid condition. 
         [0032]    Although the foregoing disclosure has been described in some detail by way of illustration and example, for purposes of clarity or understanding, certain changes and modifications may be practiced within the scope of the appended claims.