Surgery – Instruments – Cutting – puncturing or piercing
Utility Patent
1999-07-08
2001-01-02
Buiz, Michael (Department: 3731)
Surgery
Instruments
Cutting, puncturing or piercing
C606S170000
Utility Patent
active
06168605
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates, in general, to handheld surgical instruments and, more particularly, to a new and useful handheld surgical cutting instrument having scissor blade members formed with two arcs of curvature.
BACKGROUND OF THE INVENTION
Hand held surgical instruments are well known in the surgical community and have been used for centuries. Many of these instruments have been used for grasping, dissecting, cutting, ligating, or fastening objects to the body. Of interest are hand held surgical cutting instruments such as scissors that are used to cut tissue during a surgical procedure. Scissors are well known in the art and generally consist of a pair of blade members having inner opposed cutting edges that are co-operably connected about a common pivot member. Of special interest are hand held surgical cutting instruments that are adapted to operate laparoscopically, that is, in a minimally invasive surgical procedure wherein the surgery is performed through a small number of small diameter surgical access ports rather than through a large opening or incision within the patient.
In a typical laparoscopic surgery, the abdominal cavity is insufflated with an inert gas and surgical access ports are inserted into the patient. Laparoscopic scissors are inserted into the access ports and the surgical procedure is performed through these access ports. Laparoscopic surgery is sometimes referred to as “keyhole surgery” wherein the access ports are the “keyholes” through which the surgery is performed. As a consequence of the access port (“keyhole”) size, laparoscopic scissors are characterized by a pair of scissor-like handles, a small diameter elongated shaft that forms a gas tight seal with the access port, and a small scissors end effector that is operatively coupled with at least one of the handles. Many laparoscopic scissors are curved to provide better visibility during laparoscopic surgery and to provide an improved angle of attack for electrocautery.
Laparoscopic scissors instruments are frequently provided with an electrocautery pin that can be operatively coupled to a RF electrosurgical generator by a connector cable. The RF generator provides both a cutting and a coagulating RF waveform that can be applied to tissue with either the cutting edges of the blades (to reduce bleeders during cutting) or with the outside of the flat faces of the curved scissors blades during spot coagulation. As mentioned above, the angle of attack of the curved scissors blades provides a definite benefit over conventional straight scissors blades when performing spot coagulation.
Surgical scissors instruments face an exceptionally daunting task as they must provide a good clean cut in a wide variety of tissue types that can range from a “soft” tissue such as liver tissue, to a tough resilient tissue such as peritoneum or ligaments. During open and laparoscopic surgery, it is important to provide surgeons with scissors instruments that continuously provide good cutting action throughout the surgical procedure, and that the cutting action does not deteriorate with use. Instruments that do not exhibit good cutting action generally produce partial cuts. The portion of the tissue that is not cut is generally pinched between the blades and can become crushed or damaged. The portion of uncut tissue is frequently referred to as a “tissue tag”.
Two factors affect the cutting ability of a surgical scissors instrument—the sharpness of the cutting edges of the blade members and the ability to preload or bias the cutting edges of the blade members together. When the cutting edges are biased together, they produce a single moving point of cutting edge contact as the blades close. Like a dull knife, dull blade members have difficulty cutting tissue and frequently produce a partial cut. Even when the dull blade members are adequately biased together during the cutting stroke, the dull blade members can pinch or wedge uncut tissue between the blade members and splay or spread the blade member tips apart. Producing sharp scissors blades is well known in the art and future discussions will be limited to biasing the cutting edges together.
When the cutting edges of the blade members are not adequately biased together, the scissors blades easily splay or spread apart. When this happens, the moving point of contact between the cutting edges of the scissors blades is broken and the surgical scissors instrument may not cut. Holding the blade members together is well known in the art and has generally been addressed in the following three general ways: a) camming the blade members, b) forming the blade members with a longitudinal bow or bend, and c) holding or biasing the blades tightly together at the pivot member. These methods have been used singly and in combination.
Camming the blade members generally involves the addition of a cam surface proximal to the pivot member and on the inside surface of each blade member. The pivot member holds the blade members together and as the blade members close, the cam surfaces bias the portions of the blade members proximal to the pivot member apart and the portions of the blade members distal to the pivot member together. Thus, the proximal cam surfaces effectively bias the distal cutting edges of the blade members together to produce a single moving point of blade contact. Camming the blade members together is well known in conventional scissors art and was described by M. Parker et al. in U.S. Pat. No. 1,956,588. Parker et al. teaches the use of a pivot pin to hold the blade members together.
Whereas the cams used in the conventional scissors described by Parker et al. were indeed revolutionary, they were costly. William Hembling in his U.S. Pat. No. 4,420,884 described forming the blade members by progressively stamping sheet metal to produce a control cam proximal to the pivot member to bias the cutting edges together, and an arcuate blade cross section to produce the effect of hollow grinding. Hembling's invention described camming the blade members together in the manner of M. Parker et al. but at a much lower cost. The blade members were held together in the manner of Parker et al.
Although the use of cams to bias conventional non-surgical scissors together was historically well known, the use of cams in laparoscopic surgery was not. Charles Slater in his U.S. Pat. No. 5,320,636 describes the use of cams proximal to the pivot member to bias the distal cutting edges together. Slater also discloses progressive biasing wherein the greatest bias force is applied when the blade members are open and progressively less bias is applied as the blade members close.
Whereas camming the cutting edges of the blade members together did indeed provide a distal bias force on the cutting edges of the blade members, it was still possible to splay the distal ends of the blade members. This was especially noticeable on long blades formed from a thin material such as sheet metal. What was needed was a different method of biasing the blade members together that was more resistant to splaying and, if desired, used in combination with the cams described previously. Such a method is the application of a longitudinal bow or bend to at least one of the blade members. The longitudinal bend is applied to the blade distal to the pivot member and has little or no effect on biasing the proximal portion of the cutting edges together when the blade members are open. As the blade members are closed, the longitudinal bends generally bring a central and a distal portion of the cutting edges into contact. As the blades are closed, the bias force increases and rises to a maximum when the blades are fully closed. This effect is especially useful for long thin blades where as the blades are closed, the increasing bias force helps counteract the increasing deflection caused by the distally moving point of cutting edge contact. The blade members can be overbent, a term that is used to describe when the tip of one blade member is bent over or beyond the outside of the tip of t
Koch, Jr. Robert L.
Measamer John P.
Sambi Narinderjit S.
Buiz Michael
Ethicon Endo-Surgery Inc.
Lewis William
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