Endoscopic instrument which can be bent

[0002] The present invention relates to a bendable endoscopic instrument having outer and inner coaxial tubes which are linearly displaceable in opposite directions along a common axis to provide effective pivotal displacement of the instrument's distal end having a pivot axis offset from the common axis.

[0003] Endoscopic instruments are known in which the distal end as a unit is bendable or pivotable relative to the longitudinal axis of the instrument. By way of example, reference is made to the following prior art documents which are explicitly referred to in all other respects for an explanation of all the details and applications which are not described here in depth: U.S. Pat. Nos. 5,318,528; 5,330,502; 5,354,311; German Patent DE 42 43 715 A1; German Patent DE 43 24 254 C1.

[0004] At the distal end a functional element of any kind may be mounted. This functional element is so connected via a rod to an actuating element disposed at the proximal end that the angular position of the functional element, such as the jaws of forceps or scissors, may be adjusted relative to the distal end which is suitable for bending or pivoting as a unit.

[0005] The instruments known from the aforementioned prior art documents present the disadvantage that either the distal end is not bendable over a wide field of traverse, or that the instruments require a comparatively substantial space because a single linearly displaceable actuator travels a substantial axial distance in order to pivotally displace the bendable end in a desirable position. As a result, these instruments are not suitable for application on the vertebrae of young people, for instance.

[0006] Moreover, the known instruments are not easy to sterilise.

[0007] In accordance with the present invention it has now been detected that a particularly compact and at the same time stable endoscopic instrument is obtained when the axis of rotation of the distal end does not intersect with the longitudinal axis of the endoscope. With such an arrangement of the axis of rotation of the distal end, however, the problem arises that the position of the other element relative to the distal end pivotable as a unit varies as the angular position of the distal end relative to the longitudinal axis of the instrument varies. In accordance with the invention, therefore a compensating mechanism is provided which prevents a variation of the relative angular position of the other element, e.g. the jaws of forceps or scissors, when the distal end is bent or pivoted as a unit.

[0008] The inventive bendable instrument hence presents the advantage that the distal end may be pivoted over a wide field of movement—typically ±70 degrees and more—relative to the principal axis. And the instrument is yet so compact that it can be easily inserted into a standard-diameter trocar.

[0009] In another inventive embodiment which may or may not be combined with the the hollow cylinder which serves to transfer the pivoting movement of the distal end as a unit, is guided in a bayonet element on the distal side which is provided with a bayonet flange by which it may be inserted into a bayonet socket in an external tube.

[0010] This design ensures easy dismantling and excellent stability and safe guidance and, above all, a defined assembly of the instrument after cleaning or sterilisation in the disassembled state.

[0011] In accordance with still another improvement the rod has a flexible design in the bending region in a manner known per se. The rod may have a rectangular cross-sectional area in particular, with the narrow side of the rectangle being orthogonal on the pivoting axis.

[0012] In accordance with another aspect of the invention, the rod presents a cross-sectional area in the bending region which is smaller than that in the non-bent region, having a round cross-sectional area, particularly in the common manner.

[0013] Still another feature of this invention the rod closes the jaws of the forceps, scissors, etc. or varies the angular position of the other element from the home position in response to traction or pressure in a manner known per se. The configuration of the rod as tie rod presents the particular advantage that the rod may also consist of a cable (Claim 4) at least in the bending region.

[0014] The invention further discloses an actuator element is provided on the proximal side which when actuated causes the distal end to bend or pivot, respectively. This actuator element may be a set screw in particular which displaces, via a threaded engagement, a hollow cylinder arranged concentrically with the rod and which operates a pivoting element which varies the angular position of the distal end and is preferably fixedly connected to the distal end. The pivoting element and the hollow cylinder may be operatively connected to each other, particularly via a pin engaged in a groove.

[0015] A further improvement in accordance with the invention is that the set screw turns, via a threaded engagement, an intermediate element which displaces the hollow cylinder via different threads and the external tube in a suitable manner for compensation in terms of length. The thread for driving the hollow cylinder may be a left-hand thread and the length-compensating thread may be a right-hand thread. The set screw may be displaced in concentric relationship with the longitudinal axis or at an angle of 90° relative to the longitudinal axis.

[0016] In the preferred improvement the distal end or the distal head is provided for rotation about the longitudinal axis into several indexed positions or locking positions so that the surgeon is able to set certain important angular positions rapidly. It is moreover expedient to have a stop or the like on the handle which makes it possible to release the head for rotation or lock it in a certain position.

[0017] In another aspect of the invention the hollow cylinder presents two opposing elastic bulges in its proximal terminal zone, which are used for insertion into recesses of a complementary shape in a tube prevented from rotation. This protection of the hollow cylinder from rotation and hence an opening of the bayonet lock is achieved via the inserted rod which prevents the bulges of the hollow cylinder from resilient engagement and hence a rotation or disassembly of the instrument.

[0018] The inventive instrument may be used for the most different medical operations. Its application in surgical operations for coelioscopy or endoscopy, respectively on the vertebrae of young patients is particularly expedient, in which cases the introduction of the endoscopic instruments from the anterior side of the thorax is to be preferred because operations on the posterior section of the vertebrae, specifically in succession on several vertebrae, are then possible without the necessity to retract the instrument. The operations may be controlled from the region in the vicinity of the handle on account of the various rotational or pivoting movements.

[0019] In the following, the invention will be described in more details by exemplary embodiments, without restriction of the general inventive idea, with reference to the drawing, which is explicitly referenced in all other respects as far as the disclosure of all inventive details is concerned which are not explained thoroughly in the text. In the drawing:

[0020] FIG. 1ais a longitudinal sectional view taken through an inventive instrument;

[0021] FIGS. 1band 1cillustrate enlarged details of FIG. 1a,

[0022] FIGS. 2a,3 and 4 are each a cross-sectional view taken through the element illustrated in FIG. 1aat the locations a—a, b—b and c—c, and

[0023] FIG. 2bis a plan view on the sectional plane a—a.

[0024] An endoscopic instrument illustrated in FIG. 1 includes coaxially positioned an external tube 4 and an internal hollow cylinder 5 which extend along a center axis 2. As will be explained in detail hereinbelow, opposite axial displacement of the tube and the cylinder causes the distal end 1 of the instrument to move axially and rotatably to bring an engaging element 7 in at least one angular position, as shown in FIG. 1b.

[0025] Particularly, the distal end 1 includes a pivoting element 11 formed with a curved groove 12 and a bayonet flange 31, which detachably engages a bayonet socket 32 of the external tube 4 for axial displacement therewith. Due to the bayonet connection, the bayonet flange 31 is axially aligned with the external tube and the cylinder 5 during their displacement.

[0026] In accordance with the invention, the bayonet flange 31 and the pivoting element 11 are rotatably interconnected by means of a pin 1aextending along a rotation axis which is spaced radially from the longitudinal axis 2. As a consequence, the pivoting element and the bayonet flange 31 angularly move relative each other about the pin 1aupon applying an external torque. This is accomplished by a cam mechanism including the above-mentioned groove 12 and a pin 13 extending radially outwardly from the cylinder 5 and slidably engaging the groove.

[0027] The structure, as described above, allows the pin 13 to follow a curved path of the groove's surface as the cylinder 5 moves toward the distal end while the external tube 4 and the distal end are displaced toward a proximal end of the endoscopic instrument. As a result, the pivoting element 11 rotates relative to the rest of the structure about the pin 1ain at least one angular position. Critical to the invention is the fact that an axial stroke, at which both the tube 4 and the cylinder 5 are displaced, is relatively short compared to an instrument in which such pivotal displacement is caused by a single axially displaceable actuator.

[0028] A rod 6 is guided in the hollow cylinder 5, which is connected to an actuator element, e.g. two hand-pieces or a thumb-operated lever, which is disposed on the proximal side and not illustrated here. The operation of the actuator elements on the proximal side causes a variation of the angular position of the engaging element disposed on the distal side relative to the element pivotable as a unit, which engaging element is provided in the form of scissors in the embodiment illustrated here, without a restriction of the general inventive idea.

[0029] FIG. 1cillustrates a possibility of operation of the scissors jaws 71 and 72.

[0030] With the axis of rotation 1aof the distal end 1, which can be rotated or bent as a unit, not intersecting the longitudinal axis 2 of the endoscopic instrument, a pivoting or rotating movement would cause a variation of the angular position of the engaging element 7 provided on the distal side relative to the distal end 1.

[0031] In accordance with the invention therefore a compensating mechanism allowing the external tube and the hollow cylinder to have short axial displacement is provided.

[0032] A setting element is provided for adjustment of the angular position of the distal end 1, which is configured as a set screw 8 (FIG. 2a). FIG. 2bis a plan view on the actuating button 81 of the set screw 8. The set screw is connected via a thread connector to an intermediate element 9. The intermediate element 9 rotatable about the axis 2 due to actuation of the set screw 8 to axially displace the hollow cylinder 5 via a left-hand thread and the external tube 4 via a right-hand thread. The thread pitches are so dimensioned that the tube 4 and the cylinder 5 travel a short distance and bring the distal end 1 in a desirable angular position upon a fewer turns of the set screw 8. Pins are provided for operation of the hollow cylinder or the external tube, respectively, which are supported on respective bearing faces.

[0033] At its proximal end the hollow cylinder 5 is provided with two opposite elastic bulges 51 and 52 for protection from rotation. The cylinder can be inserted via these bulges 51 and 52 into recesses of a tube 10 of complementary shape. Upon reaching a desirable angular position of the distal end 1, the rod 6 can be pushed toward the distal end through the cylinder 5. The rod is sized to have differently sized segments of its outer surface with a relatively large surface pressing against the bulges 51 and 52 in order to displace them radially outwardly, as shown in FIG. 4, thereby arresting further axial displacement of the cylinder 5 which, thus, locks the pivoting element 11 along with the engaging element in a desirable angular position.

[0034] As shown in FIG. 4, the instrument has an outer annular sleeve 140 receiving an annular element 110 which has flat axial inner surfaces formed complimentary to flat surfaces of the external tube 4. Thus, rotation of the set screw 8 can impart only axial linear displacement to the tube 4.