Device for use in cutting threads

A device is provided for cutting threads, particularly curing surgery carried out using an endoscope. The device has a cutting member having at least one aperture extending therethrough of a size sufficient to permit the surgical thread to slide therethrough, the aperture having a thread-cutting edge. In use, the cutting member is located at the distal end of an endoscope.

This invention relates to a device for use in cutting threads. It is 
particularly for use in cutting threads during surgery, and, more 
particularly, in surgery carried out using an endoscope. A primary 
intended field of application of the invention is in surgery carried out 
using a flexible endoscope, though it is applicable also to surgery where 
a rigid endoscope is used. 
In conventional surgery, the threads used, for example, in forming sutures, 
are normally cut using scissors. However, this option may not be open to 
someone carrying out surgery down a flexible endoscope. In such surgery 
the surgical tools used are located at the distal end of the endoscope, 
and must normally be manipulated by control means extending down a channel 
in the endoscope. Manipulating conventional scissors in this way is at 
least difficult, and may be impossible. It is also known to use a 
guillotine, but no satisfactory guillotine is believed currently to exist 
for endoscopic use. 
According to the present invention there is provided a device for use in 
cutting a surgical thread, which comprises a cutting member having at 
least one aperture extending therethrough of a size sufficient to permit 
the surgical thread to slide therethrough, the aperture having a 
thread-cutting edge, and means for enabling the cutting member to be 
located at the distal end of an endoscope.

The thread cutter according to the present invention comprises a cutting 
member 3 mounted on the distal end of a flexible wire 4. By way of 
example, the wire 4 can be a 1 mm wire made of steel of a surgically 
acceptable type. In an alternative embodiment, the wire 4 may be replaced 
by a Bowden cable. The proximal end of the wire is fixed in a mounting 
member 5, which is of a suitable size and shape to be grasped by the 
surgeon during use of the thread cutter. The wire 4 is surrounded by a 
plastics tube 6 which is not connected either to the cutting member 3 or 
the mounting member 5, and in which the wire 4 is freely slidable. The 
tube 6 is preferably made of polytetrafluoroethylene, or other material 
having a low coefficient of friction, and is intended to enable the 
cutting member and its wire to be readily passed down the channel 2, and 
withdrawn therefrom. It must be kept in mind that, in practice, the 
endoscope 1, when in position in a patient, will have a number of bends in 
it, and care therefore needs to be taken to ensure that the cutting member 
and its wire can move freely along the channel 2, despite the presence of 
these bends. 
The cutting member 3 is provided with two apertures 7 which extend from the 
front face 8 to the side wall 9. The cutting member 3 is preferably 
cylindrical in shape, and the apertures 7 are preferably circular in 
cross-section. The apertures must be of such a size that a surgical thread 
can slide therethrough, and it has been found convenient to use apertures 
having a diameter of 0.6 mm. Where the apertures emerge through the side 
wall 9 the circular cross-section of the apertures will give rise to an 
opening which is elliptical in shape. The curved distal portion of each 
elliptical opening provides an arcuately curved cutting edge for cutting 
the thread, as will be explained further below. 
The drawings show an example of the use of the cutting device of the 
present invention, in which the surgeon has inserted a surgical thread 10 
through a U-shaped piece of a patient's tissue 11 and has tied a knot 12 
therein. The procedure used to do this has left the two thread tails 13 
extending through a passageway in the patient's body and out through a 
bodily opening. For example, if the thread has been inserted in the lining 
of the patient's stomach, the thread ends will extend through the 
patient's gullet and out through the mouth. 
The thread cutter is then inserted into the endoscope, so that the cutting 
member 3 is located outwardly of the distal end thereof, and the mounting 
member 5 is located outwardly of the proximal end. The thread ends 13 are 
then passed through respective ones of the apertures 7, and the endoscope, 
with the thread cutter therein, is then inserted through the patient's 
mouth, insertion being continued until the cutting member 3 is adjacent 
the knot 12, a fact which can be ascertained by observation through the 
viewing channel of the endoscope. During this insertion process the thread 
tails 13 slide through the apertures 7, with the free ends thereof always 
continuing to extend out of the patient's mouth. In this way, the position 
is reached which is shown in FIG. 1. 
The surgeon then pulls on the thread tails 13 to create a tension therein, 
whilst moving the thread cutting member away from the knot, and the 
endoscope towards the knot, as indicated by the respective arrows in FIG. 
2. This has the effect of forcing the thread tails 13 against the curved 
cutting edges which, as mentioned above, are formed at the proximal ends 
of the passages 7. The fact that these cutting edges are curved means that 
the thread tails 13 tend to remain approximately central with respect to 
the length of the cutting edges. If the cutting edges were straight, with 
the opening in which they were formed being, say, rectangular, there would 
be a tendency for the thread tails 13 to slip to one or other end of the 
cutting edge, and this might impede an effective cutting action. 
As shown in FIG. 3, the procedure just described has the effect of causing 
the thread tails 13 to be cut, and they can then be removed through the 
patient's mouth. The final result is shown diagrammatically in FIG. 4.