This invention broadly relates to laparoscopic surgical devices. More particularly, the invention relates to laparoscopic surgical scissor instruments where the scissor end effectors are uniformly comprised of a cobalt based alloy and are formed by casting.
The laparoscopy procedure has recently become a widely practiced surgical procedure. A laparoscopy procedure typically involves incising through the navel and through the abdominal wall for viewing and/or operating on the ovaries, uterus, gall bladder, bowels, appendix, although more recently, incisions and insertion of trocar tubes have been made in different areas of the abdomen and even in the chest cavity. Typically, trocars are utilized for creating the incisions. Trocar tubes are left in place in the abdominal wall so that laparoscopic surgical tools may be inserted through the tube. A camera or magnifying lens is often inserted through the largest diameter trocar tube (e.g. 10 mm diameter) which is generally located at the navel incision, while a cutter, dissector, or other surgical instrument is inserted through a similarly sized or smaller diameter trocar tube (e.g. 5 mm diameter) for purposes of manipulating and/or cutting the internal organ. Sometimes it is desirable to have several trocar tubes in place at once in order to receive several surgical instruments. In this manner, organ or tissue may be grasped with one surgical instrument, and simultaneously may be cut or stitched with another surgical instrument; all under view of the surgeon via the camera in place in the navel trocar tube.
The laparoscopic tools of the prior art are primarily reusable stainless steel tools. The use of stainless steel for surgical instruments started in the early 1900's. Recently, almost all surgical scissor type instruments, including laparoscopic scissors, use stainless steel exclusively. One reason for the broad usage of stainless steel which contains about 11-27% (and typically 12-18%) chromium, is that stainless steel is generally hard and highly resistant to corrosion. Stainless steel however, is not easily castable into small precision components. Thus, if an attempt is made to cast stainless steel parts such as precision end effectors for laparoscopic tools, invariably the stainless steel parts require finishing; i.e., buffing and polishing to remove imperfections. Also, while stainless steel is a hard material as represented by standard indentation tests, it is subject to scratching, and the narrow grooves resulting from scratching are disadvantageously the site of potential contamination. A further disadvantage of stainless steel end effectors is that they tend to break or nick upon the inadvertent cutting of surgical staples.
Recently, as disclosed in U.S. Pat. Nos. 5,133,727 and 5,192,298, investment cast bronze end effectors have been utilized to great advantage. However, because bronze is a relatively soft alloy, the use of investment cast bronze as end effector scissor elements is not advantageous.