Over the years various surgical instruments for joining tissue have been developed. Most instruments have been developed utilizing metal staples for joining the tissue. The metal staples are relatively rigid, have their legs sharpened to readily penetrate the tissue, and once penetrated may then be crimped into a clinched position to hold the tissue together as is well known in the art. Instruments of this type are more fully disclosed and described in U.S. Pat. Nos. 3,080,564, 3,079,606, 2,891,250, 3,589,589, 4,207,898 and 4,351,466.
Generally, the instruments comprise a movable member or jaw and a stationary member or jaw. The movable jaw usually carries the metal staples and the stationary jaw carries an anvil which clinches or bends the legs of the staple that pass through the tissue. In use, the tissue is placed between the jaws, the jaws brought to the appropriate gap and the staples driven through the tissue and clinched to set the staple. A major problem with these instruments is the use of the metal staple. While metal staples provide desired hemostatsis in the joining of the tissue, they remain in the tissue and can disrupt future diagnostic techniques such as X-ray diagnosis, computer axial tomography, nuclear magnetic resonance, and the like. To eliminate this problem, it has been found desirable to develop instruments which can place non-metallic fasteners. These are fasteners made from biologically absorbable or non-absorbable polymeric materials. Examples of such non-absorbable polymeric materials would be the polyolefins, polyesters, and the like. Examples of the absorbable polymeric materials would be the polymers and copolymers of glycolide, lactide, dioxanone, etc. These polymeric materials do not have the dead-bend morphology of a metal and, hence, they cannot be clinched in the same manner as a metal staple. To use these polymers, the fasteners are designed as two-piece fasteners. This means one piece of the fastener is placed on one side of the tissue to be joined and the second piece of the fastener is placed on the other side of the tissue to be joined. One piece of the fastener is a U-shaped staple which has legs which are caused to penetrate the tissue. On the opposite side of the tissue is the second fastener piece or receiver which is a member used to engage the legs to interlock therewith after the legs have penetrated the tissue and, hence, join the tissue together.
As can be appreciated this major change in design and configuration of fasteners causes a number of problems. First, the fasteners must be designed to be sufficiently sharp and strong to penetrate the tissue or in certain instances some means must be used with the fastener to assist the fastener in penetrating the tissue. Also, the fasteners must be designed to develop some interlocking between the two pieces.
These differences cause various types of forces to be used when joining the tissue together, and these forces are different from the forces required when joining tissue using metallic fasteners and in some instances considerably greater forces are required. Also, when utlizing the two-piece fasteners, alignment between the two fasteners is critical. As can be appreciated, when applying these fasteners the instrument must hold the pieces until one piece has penetrated the tissue and the opposite piece is interengaged and locked on to the penetrating portion of the other fastener. Once this is accomplished the instrument must then release both pieces preferably simultaneously. An object of the present invention is to provide an instrument that has a stationary jaw and a movable jaw which may be easily and readily aligned when placed on opposite sides of tissue to be joined. It is also an object of the present invention to provide an instrument that releasably holds both staples and receivers in a manner to allow their ready placement in tissue to join tissue together. It is a further object of the present invention to provide a suitable instrument which can accept and control the various forces required when placing two-piece non-metallic fasteners. Further objects and purposes of the present invention will be readily apparent from the following detailed description.