1. Field of the Invention
This invention relates to a novel surgical stapling instrument, particularly useful in intralumenal anastomosis and characterized in affording semi-disposable properties. This invention particularly relates to a surgical stapling instrument employed in placing two or more evenly spaced, laterally aligned rows of staples in an internal organ during a surgical procedure.
Such instruments generally comprise two elongate jaw members, respectively affording a staple holder and an aligned anvil for closing the staples. The staple holder is designed to afford at least two rows of spaced staples on either side of a longitudinal opening in the anvil member. A slider assembly including a knife is provided to move longitudinally along the jaw members to eject and close staples while severing the tissue by passage of the knife through the longitudinal opening in the anvil member.
It is noted at the outset that the prior art sometimes uses the term "pusher bar" to describe what is herein referred to as the "slider assembly." We further note that the term "pusher bar" is herein used to describe a component of the disclosed invention that is distinctive from the "slider assembly."
2. Description of Related Art
In earlier prior art instruments, the staple holders, associated anvil members, and slider and knife assemblies have typically been constructed of disposable plastic materials and low-cost metals. Frame members of the instruments have been made of more durable materials suitable for sterilizing so that the instruments could be available for repeated use. By way of example, one instrument of this type is disclosed in U.S. Pat. No. 3,499,591, the disclosure of which is incorporated herein by reference.
More recent prior art instruments have been designed to be wholly disposable. This eliminates the need for repeated sterilization and insures that the instrument is ready for use without concern for necessary preparatory steps. Inasmuch as the instrument is to be discarded after one surgical operation, its design typically employs readily available, low-cost materials of construction to achieve an economically attractive result.
In such stapling instruments, large forces are generated when the tissue is clamped between the jaws, the staples are made to pass through the tissue, and the staples are closed in contact with aligned depressions in the anvil. These forces are of such a magnitude as to typically cause vertical separation and lateral distortion of the jaws and thus affect correct staple closure. Such forces become a primary concern when lighter materials are used, as, for example, in the design of the disposable instrument.
Earlier prior art instruments were designed to provide that the knife blade was an integral part of the sterilizable instrument so that the knife blade was resused when the unit was reloaded with staples for future use. With time, the knife blade became dulled by the repeated stapling procedures so that cuts were no longer as clean as with an unused blade.
More recent prior art, providing fully disposable surgical staplers, as suggested by U.S. Pat. No. 4,429,695, does not provide for replacement of the staple holder. Accordingly, the instrument must be abandoned after one firing process even though the operative surgical procedure may call for more staples or for more than one stapling operation. The need for a second instrument in a single patient's operation leads to more expensive procedures.
Further, support shoes which are carried by the slider and knife assemblies to provide vertical and lateral support to the jaws regularly encounter friction forces that make pushing difficult and do not permit the smooth, sliding action helpful to successful stapling procedure.
Recent prior art instrument designs generally require the use of a knife blade because the support shoes are connected to a plate member which passes through the tissue and thus must follow behind the knife blade. The support shoes in these prior art instruments restrain the jaws from vertical separation and lateral distortion.
In the prior art, the slider assembly (sometimes referred to as the "pusher bar" in the prior art) is designed to provide a thumb tab projecting laterally outward from between the upper and lower frame members on only one side of the instrument so that the propulsion of the pusher bar is effected by one hand laterally displaced from the longitudinal movement of the pusher bar. This action may place disorienting strains on the normal movement of the slider assembly and the instrument and may also affect the placement of the staples in the tissue.
There remains a need for an improved surgical stapler instrument, employing economic materials of construction, which can provide for the affording of sufficient staples to complete a patient's surgical operation, for the minimization of forces tending to hinder proper operation of the instrument, and for more convenient manipulation during the surgical operation procedure. Additionally, there remains a need for making the inclusion of a knife unit optional, as a matter of economy where one is not needed.