Seal members for surgical trocars

#This invention generally relates to surgical instruments; and more particularly, the invention relates to surgical trocar assembly devices for providing communication into an anatomical cavity. The trocar assembly devices in accordance with the present invention include an improved seal member that is able to maintain sealing engagement during off-centering or radial motion of elongate surgical instruments extending therethrough.

#A trocar assembly is a surgical instrument that is used to gain access to a body cavity. A trocar assembly generally comprises two major components, a trocar tube and an obturator. The trocar tube having the obturator inserted therethrough is directed through the skin to access a body cavity through the tube in which laparoscopic or arthroscopic surgery and endoscopic procedures are to be performed. In order to penetrate the skin, the distal end of the trocar tube is placed against the skin which has been cut with a scalpel. The obturator has a sharp point or cutting edge at its distal end. By applying pressure against the proximal end of the obturator, the sharp point is forced through the skin until it enters the body cavity. The trocar tube is inserted through the perforation made by the obturator and the obturator is withdrawn, leaving the trocar tube as an accessway to the body cavity. Examples of trocar assembly devices are disclosed in U.S. Pat. No. 4,535,773.

#The proximal end portion of the trocar tube is typically adjoined by a housing that defines a chamber having an open distal end portion that communicates with the interior lumen defined by the trocar tube. An obturator and other elongate surgical instruments or tools axially extend into and are withdrawn from the trocar tube through the proximal end portion of the chamber. It is the present practice to provide the chamber with a sealing means, such as a sealing grommet or gasket, through which the obturator or other instruments extend. The sealing means seals against the outer surface of the inserted instruments and thereby prevents fluids and insufflation gas from leaving or entering the body cavity through the trocar tube.

#A more complete appreciation of this invention, and many of the attendant advantages thereof will be readily apparent as the same becomes better understood by reference to the following detailed description, when considered in conjunction with the accompanying drawings, in which like reference numerals indicate the same or similar components, wherein:

#FIG. 1 is a cross-sectional view taken through a trocar assembly device that includes a seal member constructed in accordance with a preferred embodiment of the invention;

#FIG. 2 is a cross-sectional view of the trocar assembly shown in FIG. 1 through a plane that is oriented 90.degree. from the plane through which FIG. 1 is taken;

#Referring to FIGS. 1-3, an exemplary trocar assembly 10 is shown that includes a seal member constructed in accordance with the invention as disclosed in copending U.S. patent application Ser. No. 07/779,040, which disclosure is incorporated herein by reference. The particular construction of the trocar assembly does not form a part of the invention. Trocar assembly 10 includes an outer trocar tube 12 and an inner trocar tube 14. Inner trocar tube 14 is extendable through outer trocar tube 12.

#Outer trocar tube 12 defines an interior lumen 16 and has an open proximal end portion 18 and an open distal end portion 20. The inner diameter of trocar tube 12 at its distal end of distal end portion 20 is preferably in the range from about 15.0 mm to about 50.0 mm, and most preferably in the range from about 30.0 mm to about 40.0 mm. The proximal end portion 18 of outer trocar tube 12 is of increased dimensions to form a handle or housing portion 22 defining a chamber 24. The opening in the proximal end of the housing is defined by ring portion 25.

#Inner trocar tube 14 defines an interior lumen 26 and has an open proximal end portion 28 and an open distal end portion 30. The inner diameter of trocar tube 14 at the distal end of its distal end portion 30 is preferably in the range from about 5.0 mm to about 15.0 mm, and most preferably in the range from about 10.0 mm to about 12.0 mm. For reasons that will hereinbelow become more apparent, trocar tube 14 has an intermediate portion 31 that has an increased diameter such that the outer surface thereof slidingly contacts the inner surface of outer trocar tube 12. The inner diameter of the proximal end portion 28 of trocar tube 14 is substantially equal to the inner diameter of distal end portion 30. The distal end portion 30 extends distally beyond the distal end of trocar tube 12 and tapers inwardly as it extends towards the distal end thereof. The outer surface of distal end portion 30 preferably has square toothed helical threads 32 formed thereon.