Surgery – Instruments – Cutting – puncturing or piercing
Patent
1996-10-25
1998-09-01
Buiz, Michael
Surgery
Instruments
Cutting, puncturing or piercing
604169, A61B 1734
Patent
active
058004513
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns a trocar system having a flexible trocar tube defining a lumen, a trocar plunger and a valve mechanism formed at the end of the trocar tube facing away from the patient through the valve housing of which the trocar plunger can be inserted into the trocar tube.
These types of trocar systems are known in the art from DE-OS 43 12 147. These trocar systems comprise an obturator made from rust-free steel or from another rigid material and a cannula made from plastic, such as PTFG, polyurethane or PVC. The cannula made from this type of plastic has an open proximal and open distal end and is flexible to facilitate the introduction of a curved surgical instrument through the cannula into the body cavity without having to increase its inner diameter.
Known in the art from DE-OS 41 34 655 is an atraumatic cannula having a mandrin with an outer cross section and a shaft with an inner cross section which are tapered in the vicinity of the shaft tip such that, when introducing the cannula into the tissue, the pressure on the mandrin facilitates contact between its tapering and the tapering of the shaft to "carry" same and cause stretching thereof while avoiding displacement of its material.
The trocar system in accordance with DE-OS 43 12 147 is fundamentally suitable for the introduction of a curved operation instrument into a hollow body region. However, the operation instrument can cause back and forth motion or displacement of the trocar tube within the tissue. For this reason it is necessary for the trocar tube to be securely anchored in the tissue, in particular, when very strongly curved instruments are introduced.
It is therefore the underlying purpose of the invention to further improve conventional flexible trocar systems in such a fashion that the anchoring of the trocar tube within the tissue is improved and to also guarantee the possible introduction of strongly curved instruments into the trocar tube.
SUMMARY OF THE INVENTION
This purpose is achieved in accordance with the invention in that the trocar tube is stretchable with respect to the axial length and the trocar tube is tapered at the end next to the patient, the taper interlockingly engaging a circular step or a conical section at the tip of the trocar plunger.
The taper is formed in such a fashion that it is capable of close interlocked seating in the tip region of the trocar plunger. In this fashion the tapering engages a circular step or a conical section at the tip of the trocar plunger. The interlocking connection can accept axial forces acting in opposition to the pushing and positioning direction of the trocar tube. A flange is formed at the end of the trocar tube facing away from the patient which can seat in the valve housing. The flange can be strengthened by inlays in the flange material or by support rings and is held within the valve housing in an axially non-displaceable fashion. In further embodiments of the invention, it would also be possible for the trocar tube to be held within the valve housing in a rotatable manner.
A trocar configured in accordance with this technical teaching has the advantage that the trocar tube can be pretensioned at the trocar plunger in a defined fashion. It is therefore possible to prevent an unacceptable excessive stretching of the trocar tube. In the event that the trocar tube is pretensioned it can, for example, be connected in a detachable fashion to the trocar plunger via the valve housing. Towards this end, the trocar tube is supported on the circular step of the trocar plunger and is preferentially attached at the other side to the trocar plunger via the end in proximity to the machine. In the event that the trocar plunger shaft is thinner than its tip, it is possible for the trocar plunger to easily slide within the trocar tube until the tip of the trocar plunger interlocks with the trocar tube taper.
An additional advantage of a trocar configured in accordance with the invention is that the cross section of the trocar tube is reduced when
REFERENCES:
patent: 3717151 (1973-02-01), Collett
patent: 5147316 (1992-09-01), Castillenti
patent: 5350393 (1994-09-01), Yoon
patent: 5603702 (1997-02-01), Smith et al.
Buess Gerhard
Jakoubek Franz
Krauter Joachim
Melzer Andreas
Buiz Michael
Truong Kevin
Vincent Paul J.
Willy Rusch AG
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