Surgery – Instruments – Suture – ligature – elastic band or clip applier
Reexamination Certificate
2000-05-25
2002-08-27
Milano, Michael J. (Department: 3731)
Surgery
Instruments
Suture, ligature, elastic band or clip applier
C606S208000
Reexamination Certificate
active
06440144
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a medical instrument, comprising:
an elongated shaft having a distal end and a proximate end;
a movable tool disposed at said distal end of said shaft;
a handle disposed at said proximal end of said shaft;
a force transmitting element extending along said shaft and movable in a first and an opposite second movement direction, said force transmitting element being operatively interconnected between said tool and said handle for converting a movement of said handle into a movement of said tool.
An instrument of this kind is known from DE 43 03 544 A1.
This known instrument is an applicator for applying hemostatic clips. Although the present invention is described hereinafter using the example of a clip applicator of this kind, the invention is nevertheless not limited to a medical instrument in the form of such a clip applicator, but rather can also be used with other instruments, as will be described below.
A clip applicator generally has, at the distal end of the shaft, a tool in the form of two jaw parts that are preloaded resiliently into a spread position. The two jaw parts can be pressed together, by advancing a sleeve, out of their spread position into a closed position. The sleeve is joined to an force transmitting element in the form of a push bar that in turn is joined at the proximal end to the movable grip element of the handle of the instrument. The V-shaped or U-shaped clips are arranged in the shaft, serially one behind another, in a magazine. By way of an advance mechanism, the particular clip located closest to the jaw parts is slid between the spreadapart jaw parts. Actuation of the handle moves the force transmitting element (and thus the sleeve) axially in the distal direction, thus pushing the jaw parts together out of their spread position and thereby closing the clip that is located between the jaw parts by deformation.
Clips of this kind are used, for example, to close off blood vessels or for surgical sutures.
When a clip applicator of this kind is used, the problem arises that the clip currently located between the jaw parts can fall out of the jaw parts if, during the operation of closing the jaw parts, the handle is released or the manual force for actuation of the handle is reduced before the clip has been completely closed onto the corresponding tissue or onto the vessel. In particular if the handle is preloaded by spring force into its starting position, the result of releasing the handle during the closing operation would be that the force transmitting element would move back into its starting position; as a result, the jaw parts would open, so that the clip, not yet closed, would fall out of the jaw parts. If a clip is lost in a patient's body, this can have devastating consequences if the loss is not noticed.
This problem cannot be eliminated even if defined click-stop positions, for example by way of a toothed rack, are provided on the handle or the force transmitting element, since the jaw parts can open at least a little way, corresponding to the distance between two click-stop positions, when the handle is released, so that in this instance as well the clip that is located between the jaw parts and is not completely closed can fall out. The surgeon must therefore continuously take care, during the closing operation, not to reduce his manual force on the handle so as not to interrupt the closing operation before the clip is completely closed.
The problem described above occurs, however, not only specifically with a clip applicator but also with other medical instruments in which a movable tool is present that can be moved back and forth in two opposite directions. Such an instrument can, for example, be a forceps for grasping tissue, which has two jaw parts that are closed so as to grasp tissue between the jaw parts for removal from the body. What occurs here is the comparable problem that the jaw parts can open again when the handle is released, so that the tissue being grasped can fall out as the forceps is withdrawn from the body; this must absolutely be avoided as long as the jaw parts are still in the body. Further examples of instruments in which similar problems occur are needle holders and sponge holders.
It is therefore an object of the invention to develop an instrument of the kind cited initially in such a way in the event of a reduction in manual force during actuation of the handle, or in the event the handle is released, the movable tool cannot unintendedly move back opposite to the actuation direction.
SUMMARY OF THE INVENTION
According to the present invention, this object is achieved in the case of the instrument cited initially in that steplessly acting locking means coact with said force transmitting element for steplessly locking the movement of said force transmitting element in said first movement direction, whereas said locking means allow free movement of said force transmitting element in said opposite second movement direction.
Because of the steplessly operating locking means provided according to the present invention, the at least one movable tool can be immobilized in any desired position so as not to move opposite to the actuation direction, while the actuation direction is not impeded. If the handle is released or if there is any reduction in manual force, the tool remains in the position most recently attained. In the case of a clip applicator, because of the stepless locking system the jaw parts cannot unintendedly open again if the handle is released or if there is a reduction in manual force, thus preventing the clip located between the jaw parts from falling out if the clip is not yet applied in completely closed fashion to the vessel or tissue. In the case of a grasping forceps as well, any loss of the grasped tissue inside the body is prevented. The same is true for a needle holder or sponge holder. Because the locking means coact with the force transmitting element, an additional result is an advantageously simple design of the locking mechanism. The force transmitting element remains stationary in any axial position and thus, as soon as the handle is no longer being actuated, also immobilizes the tool in the position it has just reached.
In a preferred embodiment, the locking means are configured so that they coact with the force transmitting element with clamping force in the locked direction.
This feature is advantageous because it makes possible, in a physically simple fashion, a locking system for the movement of the force transmitting element in the locking direction that operates reliably and steplessly, i.e. acts at any desired point in the movement travel of the force transmitting element.
In a further preferred embodiment, the locking means can be brought into engagement with the force transmitting element by spring force.
The advantage here is that the preloading of the locking means by the spring force makes possible reliable automatic engagement with the force transmitting element.
In a further preferred embodiment, means are provided for disengaging the locking means from the force transmitting element in order to move the force transmitting element back in the first movement direction previously locked by the locking means.
The means for disengaging the locking means thus result in cancellation of the locking effect of the locking means, so that the force transmitting element can be moved back into its starting position, after which the instrument is once again ready for the next actuation.
It is particularly preferred in this context if the means for disengaging the locking means are moved along with the force transmitting element, and in a predefined first position coact automatically with the locking means in order to disengage the latter.
It is advantageous in this context that the unlocking of the force transmitting element is also derived automatically from the movement of the force transmitting element, with no need for a manual action in order to unlock the force transmitting element. The predetermined first positi
Ho (Jackie ) Tan-Uyen T.
Karl Storz GmbH & Co. KG
Milano Michael J.
St. Onge Steward Johnston & Reens LLC
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