Clip appliers are quite well known in the surgical community and are used to ligate a blood vessel, a duct, or a portion of body tissue during surgery. Clip appliers have a pair of movable opposed jaws for holding and forming a ligation clip therebetween. The vessel is ligated or occluded when the ligating clip is crushed or formed on the vessel by the closing of the jaws. After clip formation, the jaws are opened, and the instrument must be reloaded for the next ligation. Initially, clip appliers required the manual reloading of a clip every time the instrument was fired.
The manual reloading process was time consuming and bothersome to surgeons, and the need for a multiple clip applier having both a clip forming mechanism to form a clip, and a multiple clip feeding mechanism that would repeatably feed a clip into the open jaws was recognized. The combination of a feeding and a forming mechanism was revolutionary and numerous examples of these multiple clip appliers exist in today's market. One such applier is the Ligaclip.TM. MCM30 multiple clip applier from Ethicon Endo-Surgery, Cincinnati, Ohio.
Of the multiple clip appliers that exist in today's market, there is a type of clip applier that may be considered as "automatic". The automatic clip applier is characterized as having a clip pusher and a jaw closure cam tube that move in opposite directions as the instrument is fired. Such a device was described by Deniega in U.S. Pat. No. 4,598,771 wherein a clip feeding mechanism moves proximally and a clip forming mechanism moves distally to close the clip located between the jaws. Once the clip is formed, the motions are reversed to load a new clip within the jaws. Additional multiple clip appliers are described in Green et al. U.S. Pat. Nos. 5,030,226 and 5,197,970, Stefanchik et al. U.S. Pat. No. 5,171,249, Hughett et al. U.S. Pat. No. 5,171,247, Burbank et al. U.S. Pat. Nos. 5,431,668, and Reissue No. Re. 35,525 by Stefanchik et al..
A Green et al. U.S. Pat. No. 5,541,149 describes the use of a pair of handles that are attached to the feeding and forming mechanism by a series of links in a similar manner to that taught by Burbank et al. The feeding mechanism has a clip pusher for pushing a clip into the open jaws and the forming mechanism has a camming member for closing the jaws upon the clip. The Green et al. '149 patent teaches when the handles are closed, the clip pusher moves proximally to pick up a clip and the camming member moves distally to close the jaws. As the handles are released, the camming member moves proximally to open the jaws, and the clip pusher moves distally to feed a clip in the jaws. Once the clip is fed into the jaws, the clip pusher remains in the distal most position (behind the jaws).
In many of the prior art multiple clip appliers, the positioning of the clip pusher at the distal most position is done to hold the jaws in the open position to prevent accidental closure of the jaws and to prevent proximal migration of the clip when exposed to tissue loads. In such appliers, the feeding and forming mechanisms require precise timing and coordinated movement of components to operate. For example, as the handles are initially closed, the clip pusher must first be retracted out of the jaw area or the jaws will collide with the clip pusher as they close.
This need for precise timing and control has resulted in the need for complex mechanical designs in many of the prior art clip appliers. The complexities of the components and the requirements for precision has increased the cost of the clip appliers. What is needed is a method of eliminating the requirement for precisely timed simultaneous motion of the feeding and the forming mechanisms as the handles are closed. This would reduce the precision of the components, eliminate the potential crushing of the clip pusher, and reduce costs.
It is an object of the present invention to eliminate the need for simultaneous opposed motion of the clip pusher with the forming system as the handles are closed. It is an additional object of the present invention to have the clip pusher place a clip into the open jaws of the instrument as the jaws open, and to retract the clip pusher into the shaft of the instrument when the handles are fully open. These actions eliminate the timing issues associated with clip appliers that require simultaneous motion of the clip pusher and the forming mechanism as the handles are closed.
Presently, there is no known multiple clip applier that can provide the surgeon with the improvements and benefits described above.