Surgery – Instruments – Cutting – puncturing or piercing
Reexamination Certificate
2000-06-30
2001-06-26
Truong, Kevin (Department: 3731)
Surgery
Instruments
Cutting, puncturing or piercing
C606S180000
Reexamination Certificate
active
06251120
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a medical instrument for removing tissue in the human or animal body, having a tubular shaft that has at least one window in the region of its distal end, having a cutting element that is arranged in the shaft in the region of the window and is connected to a drive shaft, extending in the shaft, by way of which the cutting element can be driven rotationally about its longitudinal axis, the shaft having at least one bending point, and the drive shaft terminating proximally from the bending point and being connected to the cutting element through the bending point by way of at least one flexible element.
An instrument of this kind is known from U.S. Pat. No. 5,320,635. An instrument of this kind, which is also referred to as a rotary cutting instrument or a shaver, is used in minimally invasive surgery to remove tissue in the human or animal body. For that purpose, the distal end of the shaft is guided through an incision into the surgical area in which the tissue that is to be removed is located. For removal of the tissue, the cutting element is caused to rotate, via the drive shaft, by way of an external or internal motor. A blade configured on the cutting element coacts in cutting fashion, during rotation, with an edge of the window of the shaft also configured as a blade, by the fact that the blades of the cutting element pass by the blades on the window at each revolution.
In addition to instruments that have a continuous straight shaft, instruments of this type are also known whose shaft has a bending point in the region of the distal end, i.e. the shaft is curved in the region of its distal end. Because of the curved configuration of the shaft, it is possible to remove portions of tissue in the body that are inaccessible or difficult to access with a straight shaft. In orthopedics, for example, portions of tissue around joint structures can be removed therewith.
In the case of an instrument having a curved shaft, there arises the problem of transferring the rotation of the inherently rigid drive shaft, through the bending point or curvature of the shaft, to the cutting element; this is problematic because the longitudinal axis and thus the rotation axis of the cutting element, and the longitudinal axis and thus the rotation axis of the drive shaft, enclose an angle that differs from zero.
In the case of the instrument known from the aforementioned U.S. Pat. No. 5,320,635, the rotation transfer through the bending point is brought about in that the drive shaft, configured as a tubular shaft, is equipped, in the region arranged in the bending point, with circumferentially delimited indentations introduced perpendicular to the longitudinal axis in the manner of a bellows, thus making possible flexibility of the drive shaft in this region. Provision is also made for the drive shaft to be made of a flexible plastic at least in this region.
A disadvantage of this configuration, however, is that the slits introduced into the drive shaft can constitute defined break points, since as it rotates, the drive shaft is exposed in the bending region to continuously alternating bending directions. This configuration of the drive shaft, in particular in the case of a miniaturized configuration of the instrument with a thin shaft, is moreover complex in terms of manufacturing and cost, since the slits must be of very fine-scale configuration and suitable tools must be used for the purpose.
A further rotational cutting instrument is known from DE-A-43 23 756. With this instrument, the drive shaft is interrupted in the region of the bending point of the shaft, the respective adjacent ends of the rigid shaft parts being connected via one or more universal joints. The universal joints have two articulation axes orthogonal to one another.
This known type of rotation transfer from the drive shaft to the cutting element again results in a complex design for the instrument. With miniaturized configurations of the instrument in particular, the universal joints must also be of miniaturized configuration. The manufacture of such miniaturized universal joints is, however, laborious.
Also known, from U.S. Pat. No. 5,669,926, is a rotary cutting instrument in which the drive shaft is connected to the cutting element, through a bending point of the tubular shaft, via a flexible coil, the coil having the same diameter as the drive shaft. This type of rotation transfer through a bending point is also associated with increased outlay for manufacture of the drive shaft.
DE 43 02 912 A1 discloses a rotary cutting instrument in which the drive shaft is constructed of gimbal elements in a curvature region of the tubular shaft.
A similar configuration of the drive shaft in the region of a bend in the tubular shaft, by arranging gimbal elements one behind another and in mutual engagement, is known from U.S. Pat. No. 5,755,731.
A drive shaft similar to the configuration of the drive shaft described in the aforementioned U.S. Pat. No. 5,320,635 is known in the case of a rotary cutting instrument disclosed in U.S. Pat. No. 5,620,447.
Lastly, U.S. Pat. No. 5,529,580 discloses a rotary cutting instrument in which the rotation transfer from the drive shaft through a bend in the tubular shaft to the cutting element is accomplished by an element similar to a helical spring.
All the aforementioned known types of flexible configuration of the drive shaft in the region of the bend in the shaft have the disadvantage of being complex in terms of design and production engineering.
It is therefore the object of the invention to develop an instrument of the kind cited initially in such a way that rotation transfer from the drive shaft to the cutting element through the at least one bending point is made possible with little complexity in terms of design.
SUMMARY OF THE INVENTION
According to the present invention this object is achieved by a medical instrument for removing tissue, comprising:
a tubular shaft having a distal end and having at least one window in a region of said distal end, said shaft further having at least one bending point;
a cutting element arranged in said shaft in a region of said window;
a drive shaft extending in said shaft and connected to said cutting element for driving said cutting element rotationally about a longitudinal axis of said cutting element, said drive shaft terminating proximally from said bending point and being connected to said cutting element through said bending point by way of at least one flexible element,
wherein said at least one flexible element is configured as a wire element whose diameter is less than a diameter of said drive shaft, and which is attached to at least one of said drive shaft and said cutting element eccentrically with respect to a longitudinal center axis thereof.
Instead of the rotation transfer from the drive shaft to the cutting element provided for in the existing art, by way of a configuration of the drive shaft equipped with indentations or by way of universal joints, in the case of the instrument according to the present invention the rotation transfer is thus brought about by way of at least one flexible wire element that connects the drive shaft to the cutting element. A connection of this kind by way of at least one flexible wire element is very simple in terms of design, so that the instrument according to the present invention can be manufactured economically with little technical complexity. In addition, because of the eccentric attachment of the two wire element ends to the drive shaft on the one hand and to the cutting element on the other hand, a rotation transfer with a favorable torque transfer is achieved. The flexible wire element furthermore has the advantage that it adapts to the curved profile of the bending point of the shaft and is thus suitable for any radius of curvature of the bending point. The wire element can be attached to the drive shaft and to the cutting element at the same angular position in each case, i.e. without a circumferential offset, or at angular positions
Karl Storz GmbH & Co. KG
St. Onge Steward Johnston & Reens LLC
Truong Kevin
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