Cam-controlled knife for surgical instrument

A surgical instrument may include a knife moveable from a stowed position completely within said surgical instrument to a cutting position in which at least part of the knife is positioned outside the surgical instrument. The surgical instrument may also include at least two cam slots, a cam pin extending from the knife into the cam slots, at least two guide slots that are substantially linear and are spaced apart from said cam slots, and a guide pin extending from the knife into the guide slots. In some embodiments, the cam slots are shaped to cause the knife to move from the stowed position to the cutting position as the knife is urged proximally.

FIELD OF THE INVENTION

The invention generally relates to surgical staplers and stapling.

BACKGROUND

An endocutter is a surgical tool that staples and cuts tissue to transect that tissue while leaving the cut ends hemostatic. An endocutter is small enough in diameter for use in minimally invasive surgery, where access to a surgical site is obtained through a trocar, port, or small incision in the body. A linear cutter is a larger version of an endocutter, and is used to transect portions of the gastrointestinal tract. A typical endocutter receives at its distal end a disposable single-use cartridge with several rows of staples, and includes an anvil opposed to the cartridge. During actuation of an endocutter, the cartridge fires all of the staples that it holds. In order to deploy more staples, the endocutter must be moved away from the surgical site and removed from the patient, after which the old cartridge is exchanged for a new cartridge. The endocutter is then reinserted into the patient. However, it can be difficult and/or time-consuming to located the surgical site after reinsertion. Further, the process of removing the endocutter from the patient after each use, replacing the cartridge, and then finding the surgical site again is tedious, inconvenient and time-consuming, particularly where a surgical procedure requires multiple uses of the endocutter.

In order to overcome these difficulties, Cardica, Inc. of Redwood City, Calif. has developed a true multi-fire endocutter that is capable of firing multiple times without the need to utilize single-use-cartridges. That endocutter is described in, for example, U.S. patent application Ser. No. 12/263,171, filed on Oct. 31, 2008; and U.S. patent application Ser. No. 12/436,101, filed on May 5, 2009 (the “Endocutter Documents”), which are hereby incorporated by reference in their entirety. The Endocutter Documents, among other items, disclose a knife or cutter used to cut tissue before, during and/or after stapling of tissue.

The use of the same reference symbols in different figures indicates similar or identical items.

DETAILED DESCRIPTION

Referring toFIG. 1, a knife2is held within a surgical instrument4in a first, stowed position. The surgical instrument4may be the staple holder of an endocutter such as described in the Endocutter Documents, the anvil or staple holder of an anastomosis stapler such as described in U.S. Pat. No. 7,285,131, which is hereby incorporated by reference in its entirety, or any other suitable surgical instrument. The knife2may have a cutting edge6that in the first, stowed position is oriented at least partially upward. The knife2may include a first aperture8and a second aperture10located above and spaced apart from the first aperture8. A first pin12may extend into or through the first aperture8, and a second pin14may extend into or through the second aperture10. Advantageously, the knife2is rotatable about the second pin14. Alternately, the second pin14may be fixed to the knife2. The second pin14may extend to and be movable longitudinally by a drive bar or other feature as set forth in the Endocutter Documents. The first pin12may simply extend into a cam slot20defined in the surgical instrument4, and thus may be fixed to the knife2, or rotatable relative to the first aperture8.

The cam slot20may have any suitable path for controlling the knife2. As one example, the distal end of the cam slot20may be generally longitudinal, and generally parallel to and spaced a first distance apart from a lower surface24of the surgical instrument4, and the proximal end of the cam slot20may be generally longitudinal, and generally parallel to and spaced a second distance apart from a lower surface24of the surgical instrument4, where the second distance is greater than the first distance. Between those ends of the cam slot, a ramp26may extend upward in the proximal direction. Alternately, the cam slot20, rather than being linear, may define a closed two-dimensional path, such that return of the knife2to the first, stowed position is accomplished along a different path than the motion of the knife2away from the first, stowed position. The second pin14may move generally longitudinally along a guide slot22. As shown inFIGS. 1-3, the guide slot22is linear, and thus does not cam the knife2relative to the surgical instrument4. However, the guide slot22could be configured to cam the knife2relative to the surgical instrument4, such as by introducing nonlinearity to the guide slot22, and if so the guide slot22may be characterized as a cam slot20.

The second pin14may be pulled longitudinally and proximally along the guide slot22during actuation of the surgical instrument4, such as by a drive bar. As the second pin14moves proximally, the first pin12follows along in the proximal second of the cam slot20. When the second pin14encounters and runs up the ramp26, the knife2rotates about the second pin14, due to the decrease in spacing between the guide slot22and the cam slot20. That is, the knife2must rotate about the second pin14due to the fact that the second pin14is constrained to remain in the guide path22and the first pin12is constrained to remain in the cam path20. As the knife2rotates, the cutting edge6moves out of the stowed position, and moves out of the surgical instrument4to a second, cutting position. Such motion may cut tissue placed adjacent to the surgical instrument4. As the second pin14continues to be pulled proximally, the cutting edge6moves proximally along the surgical instrument4, incising tissue as it slides. The second pin14is moved along the guide path22until the travel of the knife2is complete. The knife2may then be returned to the initial, stowed position simply by reversing the direction of travel of the second pin14toward the distal direction.