Abstract:
In accordance with the present invention there is provided an obturator for penetrating body tissue which contains a handle and a shaft. The shaft has a proximal end attached to the handle and a distal end extending from it. The handle and shaft are formed from a single piece of molded polymer. A substantially rigid reinforcing member which is formed from a material having a greater rigidity than the molded polymer is disposed along the shaft.

Description:
FIELD OF THE INVENTION 
     This invention generally relates to surgical instruments; and more particularly, the invention relates to trocar devices for providing communication to the abdominal cavity. Trocar devices in accordance with the present invention include a substantially reinforced obturator shaft which adds rigidity to overcome unwanted deflection during penetration. 
     BACKGROUND OF THE INVENTION 
     A trocar is a surgical instrument that is used to gain access to the abdominal cavity. A trocar generally comprises two major components, a cannula and an obturator. In order to penetrate the skin, a small incision is made by the surgeon where the trocar is to be inserted. The distal end of the trocar is then inserted into the tissue. The obturator has a point or cutting edge at its distal end. By applying pressure against the proximal end of the obturator, the point is forced through the tissue until it enters a target location, such as the abdominal cavity. The cannula is inserted through the perforation made by the obturator and the obturator is withdrawn, leaving the cannula as an access to the abdominal cavity. 
     Because trocars included sharp blades, inadvertent tissue or organ puncture was a concern. One of the first technical challenges in connection with the design and manufacture of the trocar was the incorporation of features to enhance safety. Specifically, it was important to develop a safety trocar which could substantially lessen the possibility of unintentional tissue or organ puncture. A trocar which includes a safety shield on the obturator was developed to lessen the possibility of unintentional puncture. The shield is biased in an extended position to cover the penetrating tip of the obturator. When the surgeon desires to penetrate tissue with the trocar, the safety shield retracts and exposes the penetrating tip. The shield remains in the retracted position so long as pressure is continuously applied. When the surgeon fully punctures the body wall, the pressure is relieved and the safety shield returns to its extended position covering the penetrating tip. Therefore, inadvertent puncture of bodily tissue and organs within the body cavity can be avoided. An example of a trocar having a safety shield is disclosed in U.S. Pat. No. 5,709,671 issued to Stephens et al. on Jan. 20, 1998, which is hereby incorporated herein by reference. 
     While numerous trocars have been designed to prevent inadvertent puncture, there was still clearly room for improvement. Regardless of the safety mechanisms built into these instruments, there were concerns of accidental puncture to body organs. Therefore, other mechanisms for protecting tissues and organs from inadvertent puncture during surgery were developed. One such development in the design of trocars relates to the incorporation of visualization concurrently with penetration. An example of a patent which discloses a surgical penetration instrument adapted for visualization during penetration is U.S. Pat. No. 5,271,380 issued to Riek, et al. on issued Dec. 21, 1993, which is hereby incorporated herein by reference. This patent describes a penetrating instrument including a hollow, cylindrical sleeve and an imaging element attached to the sleeve at its distal end. In a preferred embodiment, it has a conical non-bladed penetrating tip to facilitate the advancement of the instrument into body tissue. The non-bladed obturator separates rather than cuts tissue while penetrating to gain access to a body cavity. In this way, the incorporation of a safety shield or another mechanism to protect tissue or organs from inadvertent puncture during insertion is unnecessary. 
     The advancement of the optical non-bladed obturator reduced safety concerns and inadvertent tissue punctures encountered with early trocars; however, there was still opportunity for improvement. The trocars in the prior art are constructed of a large number of elements requiring various techniques in assembling the optical non-bladed obturator, creating manufacturing challenges. For example, manufacturers assemble the obturator by gluing the penetrating tip on the shaft of the obturator, or by using other mechanical means known in the art. Not only is the large number of elements a challenge to assemble, there is also a significant cost associated with assembling all of these elements. 
     Many of the surgeons using the optical non-bladed obturator began using it without the aid of the imaging device. The surgeons found that they were comfortable performing the surgical procedures using tactile feed back. 
     This surgical preference and the desire to reduce manufacturing challenges and costs led to the development of a one-piece solid plastic non-bladed obturator. The one-piece solid plastic non-bladed obturator enabled the use of conventional plastic processing methods such as injection molding, thus reducing manufacturing and assembly costs. Using injection molding, the one-piece solid plastic obturator had a straight injected molded plastic shaft. However, tests showed that the force required to penetrate tissue was great enough to cause unwanted deflection of the molded obturator shaft, especially on small diameter devices. This flexibility would be problematic during tissue penetration. This invention overcomes the obturator shaft deflection problem. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is provided an obturator for penetrating body tissue which contains a handle and a shaft. The shaft has a proximal end attached to the handle and a distal end extending from it. The handle and shaft are formed from a single piece of molded polymer. A substantially rigid reinforcing member which is formed from a material having a greater rigidity than the molded polymer is disposed along the shaft. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a trocar assembly including the obturator of the present invention. 
     FIG. 2 is an exploded perspective view of the trocar showing the obturator and cannula separated. 
     FIG. 3 is a plan view of the obturator of the present invention. 
     FIG. 4 is an enlarged view of the penetrating tip of the obturator. 
     FIG. 5 is an enlarged view of the penetration tip, shown in FIG. 4 rotated 90°. 
     FIG. 6 is a cross-sectional view taken along line  6 — 6  of FIG. 5 of the preferred embodiment of the reinforced shaft of the obturator in the present invention. 
     FIG. 7 is a cross-sectional view taken along line  6 — 6  of FIG. 5 of a second, alternate embodiment of the reinforced shaft of the obturator in the present invention. 
     FIG. 8 is a cross-sectional view taken along line  6 — 6  of FIG. 5 of a third, alternate embodiment of the reinforced shaft of the obturator in the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference numerals are used in this description to designate the various components and elements of the instrument of this invention. Identical reference numerals designated in the various drawings refer to the identical element or component of the surgical penetration instrument. As used in this description, “proximal” or “proximally” refers to that portion of the instrument, component, or element which extends toward the user. Conversely, “distal” or “distally” refers to that portion of the instrument, component, or element which extends away from the user. 
     Referring to FIGS. 1 and 2, there is shown trocar  2  which incorporates obturator  20  and cannula  8  of the present invention. As illustrated in FIG. 2, obturator  20  is inserted into and through valve  10  and into sleeve housing  14  and sleeve  12 . During insertion, an internal valve (not shown) connected to valve lever  18  is opened. Seal  10  is preferably a septum valve which surrounds shaft  22  preventing any fluid or gas from escaping through cannula  8 . When shaft  22  is fully inserted into cannula  8 , hub  24  is secured to sleeve housing  14  by handle  26 . Penetrating tip  32  of obturator  20 , and a portion of the distal end of shaft  22 , extend distally from sleeve  12 . 
     In an actual surgical procedure utilizing the device of the present invention, a surgeon, using a scalpel, makes a small incision where trocar  2 , shown in FIG. 1, is to be positioned during the surgical procedure. The distal end of trocar  2  is then inserted into the tissue exposed by the small incision. After insertion into the tissue, trocar  2  is oscillated back and forth around its axis to facilitate penetration. Separators  34  and  36  on penetrating tip  32  help to separate tissue during oscillation to facilitate the advancement of trocar  2  into the abdominal cavity. 
     After penetration into the abdominal cavity is complete, obturator  20  is removed from cannula  8  by pressing buttons  51  and  52  (not shown) which releases handle  26  from sleeve housing  14 . When obturator  20  is removed an internal valve (not shown) connected to valve lever  18  closes preventing any fluid or gas from escaping cannula  8 . If desired, a pressurizing gas such as carbon dioxide can be selectively pumped through sleeve  12  via stopcock  16 . Surgical instruments, such as linear staplers, graspers, clip appliers, scopes etc. can now be inserted through cannula  8  to perform a procedure at the surgical site. 
     Referring again to FIGS. 1 and 2, cannula  8  includes sleeve  12  and sleeve housing  14 . Sleeve  12  extends distally from sleeve housing  14 . Sleeve housing  14  includes stopcock  16 , valve lever  18 , and seal  10 . 
     Obturator  20 , as shown in FIG. 3, has a shaft  22  having a proximal end  42  attached to handle  26 , and a distal end  44  extending therefrom. Handle  26  and shaft  22  are formed from single piece of molded polymer. Shaft  22  preferably includes a conical penetrating tip  32  which is integrally molded to shaft  22  at its distal end  44 . Tip  32  includes first and second separators  34  and  36  which extend outwardly from penetrating tip  32 . Handle  26  has a cap  46  attached to the proximal end  42  of shaft  22 . Cap  46  is snapped onto handle  26  and is secured thereon by an interference fit. 
     Referring now to FIGS. 4 and 5, penetrating tip  32  is molded integrally to shaft  22  at distal end  44 . Penetrating tip  32  has circular base  40  and blunt point  38  extending distally from base  40 . Base  40  is positioned adjacent to the distal end  44  of shaft  22 . First and second separators  34  and  36 , respectively, have generally straight, linear edge surfaces. Each first and second separator  34  and  36  extends longitudinally from adjacent to base  40  toward point  38  of penetrating tip  32 . First and second separators  34  and  36  are spaced about 180° from each other, and are positioned proximally to point  38 . 
     Referring again to FIG. 3, shaft  22  further includes a reinforcing member  30  disposed thereon. In the embodiment illustrated in FIG. 6, member  30  is a rigid reinforcing hollow tube made of stainless steel, titanium or any other suitable material known to those skilled in the art. Using manufacturing methods like injection molding, a polymer such as polycarbonate, or any other suitable polymer known to those skilled in the art, can be injected through member  30  wile forming shaft  22  and handle  26 . Other manufacturing methods, readily apparent to those skilled in the art, could also be used to make the present invention. 
     An alternate embodiment of the present invention is shown in FIG.  7 . In this embodiment, shaft  122 , similar to shaft  22 , includes a reinforcing member  130  disposed within the shaft  122 . Member  130  is a solid cylindrical rod made of a reinforcing material such as stainless steel, aluminum or any other material known to those skilled in the art. Using manufacturing methods like injection molding, shaft  122  and handle  126  (not shown) can be integrally molded as a single piece around member  130 . 
     FIG. 8 shows another alternate embodiment, similar to that shown in FIG. 7, wherein shaft  222  includes of a member  230  disposed therein. Member  230  is similar to member  130  but has a plus shaped cross-section. As will be appreciated by those skilled in the art, many other suitable cross-sectional configurations other than circular and plus, can be used in the present invention. 
     Although particular embodiments of the present invention have been shown and described, other embodiments will become apparent to those skilled in the art without departing form the spirit and scope of the present invention. The terms used in describing the invention are used in their descriptive sense and not as terms of limitations.