Separable economically partially disposable flexible biopsy forceps

A biopsy forceps having a disposable cable formed by helically wound wire with distal and proximal ends. The helically wound wire forms a passage therethrough from the distal to the proximal end. The biopsy forceps includes a reusable forceps instrument assembly which has a control wire passing through the passage. A pair of sharpened jaws are located at the end of the control wire and are joined to a jaw mount by means of pivot. The jaw mount includes a socket for selective coupling and uncoupling to the distal end of the helically wound wire, by rotating the distal end of the helically wound wire into or out of the socket so that the helically wound wire of the support cable can be uncoupled from the jaw mount and discarded, while the forceps assembly, including the jaw mount together with the control wire and pivotally mounted jaws can be removed as an entire assembly and resterilized for use with another support cable.

FIELD OF THE INVENTION 
Biopsy forceps with a flexible support cable, a jaw mount on the support 
cable with jaws, and a control wire to operate the jaws. The expensive jaw 
mount and jaws, and the control wire are readily removable from the 
support cable so the cable can be discarded, and the more expensive mount, 
jaws and control wire, may be cleaned and reused. Only the less expensive 
support cable need be replaced. 
BACKGROUND OF THE INVENTION 
Biopsy forceps for endoscopic usage characteristically include a pair of 
pivotally mounted jaws mounted at the distal end of a tubular support 
member. Rigid instrument constructions utilize a rigid tube for supporting 
the jaws. Flexible constructions utilize a flexible tubular cable for 
supporting the jaws. 
Rigid instruments of this type tend to be more expensive, and are intended 
to be re-used. They are designed for this, and are rather easily cleaned 
and sterilized for their next use. 
However, flexible instruments involve a different set of problems, one of 
which is the near impossibility of cleaning such instruments, especially 
when the jaw mount is permanently attached to the support cable. The 
internal dimensions and clearances are very small, and because the cables 
are tightly wound helical springs, it is impractical to reach the inside 
of the support cable to clean it. As a consequence, flexible biopsy 
forceps are usually discarded after a single use. The mount, the jaws, and 
the control wire are the greatest part of the cost of the instrument. The 
support cable is not very expensive, but the jaws are quite expensive 
because they are small, held to close tolerances, and have sharpened 
cutting edges. 
Accordingly, if an arrangement can be made such that the jaw mount can 
readily be removed and replaced, then it along with the jaws and control 
wire which are attached to it can easily be cleaned. Then the inexpensive 
support cable can be discarded and replaced with a new clean one. The 
expensive parts of the instrument are thereby saved and re-used. The only 
cost for re-use is the small expense of a new support cable. 
As simple as this objective sounds, it has not heretofore been attained 
because of the difficulty of removably attaching the mount to the 
resilient spring-wound support cable. The spring cannot be threaded, and 
it is impractical to form internal threads in the small jaw mount. 
Accordingly, the jaw mounts have been permanently affixed, such as by 
crimping, which prevents the mount from being removed and re-used. Such an 
instrument is not re-usable because it cannot be cleaned. 
It is an object of this invention to take advantage of an inherent property 
of the support cable to enable a jaw mount to be removably mounted to a 
helically-formed support cable, and then be applied readily to another 
one. 
BRIEF DESCRIPTION OF THE INVENTION 
A biopsy forceps according to this invention includes a flexible tubular 
support cable with an internal passage. The support cable has a proximal 
end and a distal end. 
A jaw mount is mounted to the support cable at its distal end. It supports 
a pair of pivoted jaws having sharp cutting edges that are moved toward 
and away from one another by a control wire. The control wire passes 
through the passage in the support cable. It connects to the jaws at the 
distal end. 
The support cable and control wire are attached to actuation means such as 
a scissor type grip, or a thumb loop and handle. Both are well-known means 
for moving a control wire in a support cable. 
According to this invention, the support cable is a tightly wound helical 
spring. It is made of a suitable metal, and of such dimensions that it can 
readily bend to conform to bends in a cavity into which it is inserted, 
such as the colon. Inherently, its outer surface has a helically shaped 
groove and crest, much like a helical thread. Because the support cable is 
inherently springy in the sense of deflectibility, it can be compressed 
radically (lengthening slightly to enable this), and will exert a 
spring-back force against a body tending to compress it. 
It follows that if the mount has a tubular socket whose internal diameter 
is suitable smaller than the outermost diametrical dimension of the 
support cable's convolutions, and can be placed over them, then the jaw 
mount will be reliably retained. 
The nearest known approach to this arrangement is to place the end of the 
support cable in a socket in the jaw mount with a net fit or an over-size 
fit, and crimp it in place. This destroys the jaw mount for re-use. 
According to this invention, the socket makes an interference fit with the 
convolutions, and is placed over them by means of rotating it around the 
cable's axis so that the convolutions tend to "thread" their way into the 
socket even though the socket has no threads. In fact, it is cylindrical. 
Removal is the reverse--the mount is simply turned in the opposite 
direction. 
Accordingly the jaws, jaw mount, and control wire, which are readily 
cleaned, can be re-used indefinitely, requiring only a new support cable 
each time. The instrument is taken apart to be cleaned and the jaw mount 
can readily be applied to a new support cable. 
The above and other features of this invention will be fully understood 
from the following detailed description and the accompanying drawings, in 
which:

DETAILED DESCRIPTION OF THE INVENTION 
A biopsy forceps 10 according to this invention includes a support cable 
11. The support cable has a distal end 12 and a proximal end 13. The 
support cable is a flexible metal helically wound wire structure having 
coil convolutions 15 with a groove 16 between adjacent convolutions, and a 
curved crest 17 at the maximum diameter of the convolutions. The 
convolutions abut each other closely, but they are not attached to one 
another. The support cable can lengthen, and its diameter can be reduced. 
In this invention, the diameter is reduced, and the support cable 
lengthens locally and slightly to enable it. 
A jaw mount 20 has a socket with an internal wall 21. Wall 21 is 
cylindrical, although it may also have a short bell-mouth section 22 or 
internal bevel to provide a lead-in for the cable. The diameter 23 of the 
cylindrical portion is smaller than the maximum diameter 24 of the 
convolutions of the support cable. 
Jaws 30, 31 are hingedly mounted to the jaw mount. They have respective 
sharp cutting edges 32, 33, which when brought against or past each other 
will cut the specimen loose. For this purpose each has a respective lever 
arm 34, 35 connected to a control wire 40. The control wire extends 
through the passage in the support cable. 
The instrument is assembled by inserting the control wire into the passage. 
Then, when the socket of the jaw mount reaches the distal end of the 
support cable, it is rotated while being axially pressed over the distal 
end. This will slightly compress the coiled structure, and the cable 
passes along the support cable very much like a threaded movement, except 
that there is no thread. 
Retention of the jaw mount is quite reliable, because of the substantial 
spring-back force exerted radially by the convolutions against the inside 
wall of the jaw mount. The amount of compression varies with the 
dimensions and characteristics of the support cable. A cable having an 
external diameter of about 2 mm, will generally be compressed 
diametrically by about 5%, the support cable being a wound stainless steel 
wire. The dimensions of the mount will be selected so its outer diameter 
will be about equal to that of the support cable. Often the support cable 
will have a coating 41 (FIG. 3) of Teflon or some other plastic. It will 
be stripped from the cable over the inserted length. The outer diameter of 
the mount and of the layer will be approximately equal. 
Accordingly, a flexible biopsy forceps can be provided whose most expensive 
parts can be cleaned, and which requires the replacement only of a 
relatively inexpensive length of cable when it is to be cleaned and 
reused. 
This invention is not to be limited by the embodiment shown in the drawings 
and described in the description, which is given by way of example and not 
of limitation, but only in accordance with the scope of the appended 
claims.