BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in greater detail, by way of example, with reference to the drawings, in which:
FIG. 1 shows a morcellating device provided with a depth stop positioned in a non-operational (stored) position;
FIG. 2 shows the morcellating device with its depth stop in an operational position;
FIG. 3 is a perspective view of the operational part of the depth stop of FIGS. 1 and 2;
FIG. 4 is a partially broken-away perspective view of a second form of depth stop;
FIG. 5 is a perspective view of a third form of depth stop; and
FIG. 6 is a perspective view of a fourth form of depth stop.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to the drawings, FIG. 1 shows a morcellating device 1 comprising a handle 2 and a cylindrical tube 3. The cylindrical tube 3 is hollow, and defines a lumen 4 therein. The distal end of the tube 3 is provided with an electrosurgical electrode assembly 5. A tissue-pulling device (not shown) is insertable into the tube 3 from the proximal end 6 thereof, the distal end of the tissue-pulling device extending in use beyond the electrode assembly 5 at the distal end of the tube 3 for gripping tissue and pulling the tissue against the electrode assembly to form a core of severed tissue within the tube. The morcellating device 1 and the tissue-pulling device are described in greater detail in the specification of our International patent application WO 2005/112806.
The morcellating device is provided with a depth stop 7 which can be fixed to the outer circumference of the tube 3 at any position along its length. FIG. 1 shows the depth stop 7 in its non-operational (stored) position, and FIG. 2 shows the depth stop in an operational position part way along the tube 3. The distal end of the depth stop 7 defines a shoulder 8 which limits the longitudinal insertion of the tube 3 into a patient's body.
FIG. 3 shows the operational part of the depth stop 7, being constituted by a collar 9 having a cam track 10 provided on its inner circumference. A cam 11, in the form of the short cylindrical rod, is positioned within the cam track 10. Rotation of the depth stop 7 relative to the tube 3 causes the rod 11 to move from a first position in which the rod is located in the deepest part of the cam track 10, to a second position in which the rod is positioned at the shallow end of the cam track. In the first position, the rod 11 does not contact the outer circumference of the tube 3, and so the depth stop 7 is freely movable longitudinally with respect to the tube. In the second position, the rod 11 tightly engages the outer circumference of the tube 3, thereby locking the depth stop 7 to the tube.
It will be apparent that the depth stop 7 can be moved from the stored position shown in FIG. 1 to any required position along the tube 3, merely by rotating the depth stop to move the rod 11 into its first position, moving the depth stop to the required position along the tube, and rotating the depth stop in the opposite direction to force the rod into tight engagement with the outer circumference of the tube.
FIG. 4 shows a second form of depth stop 21, this depth stop being constituted by a generally cylindrical inner member 22 and a tubular outer member 23. The inner and outer members 22 and 23 are formed with respective diametrical apertures 22a and 23a. The diameter of each of the apertures of 22a and 23a is slightly larger than the outer diameter of the cylindrical tube 3 of the morcellating device 1. A spring 24 is provided to bias the outer member 23 circumferentially with respect to the inner member 22. Thus, when the depth stop 21 is positioned over the cylindrical tube 3, the spring 24 biases the outer member 23 so as to move the aperture 23a out of alignment with the aperture 22a, thereby defining an aperture passing through the depth stop which is of a smaller diameter than the external diameter of the tube 3. In this position, therefore, the depth stop 21 will firmly grip the tube 3, thereby locking the depth stop to the tube.
In order to position the depth stop 21 at any given position along the tube 3, the outer member 23 is rotated relative to the inner member 22, to bring the apertures 22a and 23a into alignment, thereby permitting the depth stop to be moved freely longitudinally along the tube until it reaches a desired depth stop position. The outer member 23 is then released, so that the spring 24 rotates the outer member 23 to cause the apertures 22a and 23 to be misaligned, thereby locking the depth stop 21 to the tube. In this embodiment, the outer circumferential surface of the outer member 23 defines a shoulder for limiting the longitudinal insertion of the tube 3 into a patient's body.
FIG. 5 shows a further form of depth stop 31, this depth stop being formed in a V-shape and made of spring metal material. Each arm of the V-shaped depth stop 31 is formed with a respective aperture 32, 33, each of which has a diameter which is larger than that of the tube 3. The free ends of the arms of the V-shaped depth stop 31 are formed with rolled-over portions 34 to constitute finger-engageable members.
In use, the finger-engageable members 34 of the depth stop 31 are firmly gripped to move them towards one another. In this position, the apertures 32 and 33 can be slid over the end of the tube 3, and the depth stop can be moved freely along the tube. In order to lock the depth stop 31 at any desired position along the tube 3, it is necessary only to release the pressure on the finger-engageable members 34, which causes the apertures 32 and 33 to move out of alignment and into firm engagement with the tube. In this embodiment, the distal V-shaped arm of the depth stop 31 defines a shoulder for limiting the longitudinal insertion of the tube 3 into a patient's body.
FIG. 6 shows a fourth form of depth stop 41. This depth stop 41 is made of a spring metal wire having a central portion 42, constituted by two turns of the spring wire. The two turns define apertures 43 and 44. The end portions of the spring wire are bent over to form finger-engageable members 45.
In the position shown, the apertures 43 and 44 in the two central turns of the spring wire are define a central aperture which has a diameter less than that of the tube 3. Consequently, the depth stop 41 can be fixed to the tube 3. In order to allow the depth stop 41 to be positioned on the tube 3, it is necessary to press the two finger-engageable members 45 towards one another, so as to open up the apertures 43 and 44. The depth stop 41 can then be positioned on the tube 3 and can be moved freely therealong. By releasing the pressure on the finger-engageable members 45, the depth stop 41 can then be locked to the tube 3 in any desired position. In this embodiment, the finger-engageable members 45 define a shoulder for limiting the longitudinal insertion of the tube 3 into a patient's body.
It will be apparent that modifications could be made to the morcellating device described above. In particular, other forms of depth stop could be utilised in place of the particular embodiments described. Thus, any suitable form of stop could be used, provided it is constructed in such a manner that, in a first configuration, it defines an internal aperture that is larger than the exterior of the tube, whereby the stop can freely move longitudinally with respect to the tube; and, in a second configuration, it defines an internal aperture which is sized for frictional engagement with the exterior of the tube, whereby the stop can be fixed to the tube in any predetermined position therealong. In particular, the depth stop could be a simple friction-fit ring.
It will also be appreciated that the any one of the depth stops described above could be used with any other form of endoscopic surgical instrument, so that the invention is not restricted to the use of a depth stop for a morcellator.
Patent Application
20080065129
