Tubular sheath protective insert

A surgical instrument having a protective distal insert is provided. The instrument generally comprises a tubular member containing a push rod which is axially movable within the tubular member by means of a proximal actuation handle. The tubular member is provided with a clevis at a distal end. End effectors provided with proximal tangs and cutting or gripping portions are coupled to the clevis and are further coupled to the push rod at the proximal tangs such that axial movement of the push rod is translated into rotational movement of the end effectors. Between the arms of the clevis a protective insert is provided. The protective insert is a relatively thin and elongate U-shaped member of Nylon, PTFE, or polyolefin, having a central portion provided with a central hole, and two arm portions. The push rod extends through the central hole and the insert is oriented such that arm portions are parallel to the push rod and are further aligned with the tangs of the end effectors, such that when the end effectors are opened and closed the tangs place their load on the arm portions of the insert. A thin insulative sheath extends over the distal end of the tubular member to the clevis. The protective insert protects the sheath from cracking and splitting caused by contact of the proximal tangs against the sheath.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates broadly to surgical instruments. More particularly, 
this invention relates to endoscopic and laparoscopic surgical instruments 
having end effectors. 
2. State of the Art 
Endoscopic surgery is widely practiced throughout the world today and its 
acceptance is growing rapidly. In general, endoscopic/laparoscopic surgery 
involves one or more incisions made by trocars where trocar tubes are left 
in place so that endoscopic surgical tools may be inserted through the 
tubes. A camera, magnifying lens, or other optical instrument is often 
inserted through one trocar tube, while a cutter, dissector, or other 
surgical instrument is inserted through the same or another trocar tube 
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 
with another surgical instrument; all under view of the surgeon via the 
optical instrument in place in the trocar tube. 
Various types of endoscopic surgical instruments are known in the art. 
These instruments generally comprise a metal tubular member containing a 
push rod which is axially movable within the tubular member by means of a 
proximal actuation handle. The tubular member is provided with a clevis at 
a distal end. End effectors having a proximal tang, a lateral bore, and a 
distal cutting or gripping portion, are coupled to the clevis at the 
lateral bores and are further coupled to the push rod at the tangs such 
that axial movement of the push rod is translated into rotational or 
pivotal movement of the end effectors. The cutting or gripping portions 
may take the form of scissors, grippers, cutting jaws, forceps, and the 
like. Extending over the tubular member from the proximal actuation handle 
to the clevis is a thin sheath, providing a smooth low friction surface 
for the tubular member from the proximal actuation handle to the clevis. 
On cautery-type instruments the sheath is typically FEP, providing an 
insulative cover for the metal tubular member of the instrument. 
The distal end of a prior art instrument is shown in FIG. 1. As the end 
effectors 1a, 1b are rotated from an open position to a closed position, 
the tangs 2a, 2b of the end effectors tend to move outward beyond the 
diameter of the clevis 3 and place a load on the sheath 4 at diametrically 
opposed locations 5a, 5b. It is believed that the load causes high stress 
at the two opposed locations. Repeated rotation of the end effectors 
creates sufficient stress to crack and split the sheath at the locations 
5a, 5b, reducing the insulative integrity of the sheath. In addition, 
sharp edges can result at the cracks and splits which arguably may cause 
injury on the patient in which the instrument is used and may hinder axial 
movement of the distal end of the instrument through an endoscope or 
trocar tube. 
SUMMARY OF THE INVENTION 
It is therefore an object of the invention to provide a means for 
preventing the sheath on the tube of an endoscopic or laparoscopic 
instrument from cracking and splitting. 
It is another object of the invention to provide a means for distributing 
the load of the tangs of the end effectors of an endoscopic or 
laparoscopic instrument more evenly across the distal end of the sheath. 
In accord with these objects which will be discussed in detail below, a 
surgical instrument having a protective distal insert is provided. The 
instrument generally comprises a tubular member containing a push rod 
which is axially movable within the tubular member by means of a proximal 
actuation handle. The tubular member is provided with a clevis at a distal 
end. A pair of end effectors each having a proximal tang and a distal 
portion are pivotally coupled to the clevis and are further coupled to the 
push rod at the proximal tangs. Axial movement of the push rod is 
translated into rotational movement of the end effectors. Between the arms 
of the clevis a protective insert is provided. The protective insert is a 
relatively thin and elongate U-shaped member of Nylon, Teflon, or 
polyolefin, having a central portion provided with a central hole, and two 
arm portions. The push rod extends through the central hole and the insert 
is oriented such that arm portions are parallel to the push rod and are 
further aligned with the tangs of the end effectors, such that when the 
end effectors are opened and closed the tangs engage the insert. A cautery 
connector is provided at the proximal actuation handle and coupled to the 
push rod. A thin insulative sheath extends over the tubular member from 
the proximal actuation handle to the clevis. 
It will be appreciated that when the end effectors are rotated on the 
clevis, the tangs of the end effectors will exert a load against the 
insert, and the insert will distribute the load. As a result, the sheath 
is less likely to crack and split. 
Additional objects and advantages of the invention will become apparent to 
those skilled in the art upon reference to the detailed description taken 
in conjunction with the provided figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Turning now to FIG. 2, a surgical instrument 10 is shown. The surgical 
instrument includes a proximal actuation handle assembly 12, a tubular 
member 14 having a lumen 16, a push rod 18 extending through the lumen, 
and an end effector assembly 20. The proximal actuation handle assembly 12 
includes a fixed handle portion 22 and a lever 24 pivotally coupled to the 
fixed handle portion by a pivot pin 26. The tubular member is preferably a 
rigid tube, but may also be a flexible coil. The proximal end of the 
tubular member 14 is fixedly coupled to the handle portion 22. The distal 
end of the tubular member is provided with a clevis 28. As is described in 
more detail below, a protective insert 30 is provided between the arms of 
the clevis 28. An insulative sheath 32, preferably made of FEP, extends 
over the tubular member from the proximal actuation handle to the clevis 
28, including covering the protective insert 30. A cautery connector 31 is 
provided on the proximal actuation handle and further coupled to the push 
rod 18. The push rod 18 is coupled at its proximal end to the lever 24 by 
a set screw 34 or other mechanism in a known manner and is provided at its 
distal end with a coupling means 35 for coupling to the end effector. It 
will be appreciated that the axial movement of the push rod 18 relative to 
the tubular member 14 is effected by pivotal movement of the lever 24 
relative to the fixed handle portion 22. 
Turning to FIGS. 3 and 4, the end effector assembly 20 is seen to generally 
include two end effectors 36a, 36b. The two end effectors 36a, 36b are 
each provided with a mounting bore 38a, 38b, a proximal tang 40a, 40b, and 
a blade portion 42a, 42b. The end effectors 36a, 36b are each rotatably 
mounted at the mounting bore 38a, 38b on an axle or clevis pin 44 between 
the arms 45a, 45b of the clevis 28. The proximal tang 40a, 40b of each end 
effector defines a hole 47a, 47b which is coupled by a link 48a, 48b to 
one of two holes 50a, 50b provided in diagonally opposed sides of the 
coupling means 35. The protective insert 30 is preferably a relatively 
thin U-shaped piece of Nylon, PTFE, or polyolefin. The protective insert 
30 is provided with a central portion 54 and two elongate arm portions 
56a, 56b. The central portion 54 defines a through hole 58, through which 
the push rod 18 extends, and the central portion 54 is further oriented 
perpendicular to the axle 44 and perpendicular to the push rod. As such, 
the arm portions 56a, 56b extend over the coupling means 35 and between 
the arms 45a, 45b of the clevis 28. 
By way of an example, and not byway of any limitation on the scope of this 
invention, an insert for a 5 mm curved blade scissors may be dimensioned 
such that it has an approximately 1.000 inch total length, an 
approximately 0.096 inch width, and an approximately 0.069 inch diameter 
through hole. The thickness of the material used can be approximately 
0.005 inches. 
Referring to FIG. 2 through 5, it will be appreciated that axial movement 
of the push rod 18 relative to the tubular member 14 in a distal direction 
will result in the coupling means 35 moving closer to the axle 44, and 
thereby push the links 48a, 48b and proximal tangs 40a, 40b outward to 
effect an opening of the end effector 20, whereby the blade portions 42a, 
42b scissor apart from each other (FIG. 5). Likewise, axial movement of 
the push rod relative to the tubular member in a proximal direction will 
effect a closing of the end effector (FIG. 4). 
Referring to FIG. 5, the function of the insert 30 is particularly 
illustrated. As the tangs 40a, 40b are moved outward to scissor the blade 
portions 42a, 42b apart from each other, the tangs make point contact with 
the insert 30. The insert 30 distributes the load of the contact forces 
along the length and width of the insert. Consequently, as the insert 
further distributes the load to the sheath, the stress received at any one 
point along the sheath is reduced. In addition, the protective insert acts 
to reinforce the sheath at the locations of tang contact. By reducing the 
stress at any one point on the sheath and by reinforcing the sheath the 
likelihood of the sheath cracking and splitting is reduced. 
There have been described and illustrated herein several embodiments of a 
surgical instrument having a protective insert. While particular 
embodiments of the invention have been described, it is not intended that 
the invention be limited thereto, as it is intended that the invention be 
as broad in scope as the art will allow and that the specification be read 
likewise. Thus, while a particular actuation handle has been disclosed, it 
will be appreciated that other actuation handles could likewise be used, 
such as a handle and spool arrangement, as disclosed in co-owned U.S. Pat. 
No. 5,133,727, or a rack and pinion handle, as disclosed in co-owned U.S. 
Pat. No. 5,478,350, each of which is hereby incorporated herein in their 
entireties. Furthermore, while the described instrument is shown to have 
cautery ability, it will be appreciated that instruments not having 
cautery ability but supplied with a sheath may also take advantage of the 
protective insert, as described. Also, while Nylon, Teflon and polyolefin 
have been disclosed as preferred materials for the protective insert, it 
will be recognized that other materials which act to distribute the load 
of the tangs across a larger surface area may also be used. Moreover, 
while the instrument has been described and illustrated with respect to 
end effectors having curved scissors blade portions, it will be 
appreciated that end effectors having other scissors blades, forceps, 
clamps, or other useful configurations could be used as well. Furthermore, 
while the instrument has been described as having two rotatable end 
effectors, it will be understood that an instrument having a single 
rotatable end effector can be similarly used. In addition, while the 
clevis is shown distinct from the tubular member, it will be appreciated 
that the clevis may be integral with the tubular member. It will therefore 
be appreciated by those skilled in the art that yet other modifications 
could be made to the provided invention without deviating from its spirit 
and scope as so claimed.