Flexible surgical tool with integrated bearing assembly

Abstract

The present disclosure relates to a surgical tool (1) and a surgical instrument (15), wherein the tool (1) is designed to be inserted into an instrument shaft (16, 17) of the surgical instrument (15) and has the following: a distal tool tip (2), a tool shaft (3, 4, 5) extending proximally from the distal tool tip (2) and having a distal bearing portion (3) and a drive portion (5) proximal thereto, which is designed to positively engage a drive shaft (20) of the surgical instrument (15), and a bearing bushing (8) mounted on the distal bearing portion (3) and having a bearing coupling element (10) for releasably coupling to an instrument shaft (16, 17) of the surgical instrument (15).

Description

[0001] Flexible surgical tool with integrated bearing assembly

[0002] Description

[0003] Technical area

[0004] The present disclosure relates to a surgical instrument and a surgical tool mounted or mountable therein.

[0005] In surgical techniques, it is advantageous to angle the distal section of a medical hand instrument's shaft. This allows operations to be performed in confined spaces, for example, during spinal surgery.

[0006] State of the art

[0007] In the field of surgical robots, instruments that allow for the angulation of the distal tip have long been known. This allows for precise movement of the instruments in very tight spaces. However, these instruments do not involve angulation of rotating tools. One example of this is the "Da Vinci" surgical robot from Intuitive Surgical.

[0008] Various articulating medical devices are available on the market. For example, the company Human Xtensions has developed an articulating forceps. A surgeon can use handheld robotic instruments to translate "rough" hand movements into delicate movements at the instrument tip. With this instrument, the instrument tip can be angled over a flexible area that extends over a length of approximately 20 mm. The flexible area is supported by a type of plastic stent. Adjustment is achieved using wire strands that run past the outside of the stent. The disadvantages here are the length of the bending area and the very flexible tip. This flexibility is due to the plastic stent and the wire strands. There are also already manufacturers of articulating milling handpieces / medical hand instruments.These are primarily used for endoscopic procedures on the spine and enable minimally invasive techniques as well as easy processing of hard-to-reach structures in this area. The joint constructions of these milling handpieces have a rather open design and allow for a certain degree of angulation flexibility. This means that pressure on the milling tip slightly changes the angle. Furthermore, these milling handpieces only allow angulations of up to 36°. One example of this is the milling handpiece from Joimax.

[0009] High-speed milling handpieces / medical hand instruments with angled shafts also exist. Thanks to interchangeable shafts, a handpiece can be selected from three variants: 0°, 7.5°, and 15°. The biggest disadvantage is the large bending radius used to achieve the angled position. This requires considerable space and limits the range of motion in the surgical field. Furthermore, the angle cannot be adjusted intraoperatively. Due to the fixed angle, endoscopic work with angled shafts is not possible, as they cannot be inserted into the straight working channel of the endoscope. Furthermore, the maximum angle of 15° is not particularly large.

[0010] Milling cutters with angled heads are known from DE 10 2017 010 033 A1 and US 10 178 998 B2. Both solutions are implemented using fork joints.

[0011] Summary of Revelation

[0012] The present disclosure is based on the object of reducing or avoiding disadvantages of the prior art. In particular, a surgical tool and / or a surgical instrument and / or an associated system is to be provided that is simple and cost-effective and enables precise guidance at high rotational speeds. The object underlying the invention is achieved by a surgical tool, a surgical instrument, and an associated system according to the features of the independent claims. Advantageous embodiments are the subject of the subclaims and are described in more detail later.

[0013] More precisely, the object is achieved by a surgical tool which is designed to be inserted into an instrument shaft of a surgical instrument. The tool has a distal tool tip, such as a drill or milling cutter. Furthermore, the tool has a tool shaft which extends from the distal tool tip in the proximal direction and has a distal bearing section and a drive section arranged proximally thereto. The drive section is designed for positive engagement with a drive shaft of the surgical instrument. Furthermore, the tool has a bearing bush which is mounted on the distal bearing section and a bearing coupling element for releasably coupling to an instrument shaft, in particular a distal instrument shaft section, of the surgical instrument.

[0014] In other words, a surgical tool is provided for integration into a surgical instrument, in particular into a handpiece / handheld instrument, with an integrated bearing assembly. The tool has a tool head or a tool tip, which is adapted, for example, for processing human tissue, bone, etc., and a tool shaft, at the distal end of which the tool head / tool ​​tip is arranged. The tool shaft is adapted to be inserted into an instrument shaft of a surgical instrument, in particular a hand instrument, (from a distal direction) and coupled therein to a drive provided by the instrument for driving the tool tip / tool ​​head.Furthermore, the tool has a bearing element / bearing bushing which is fastened (in particular directly) proximally from the tool head / tool ​​tip to the tool shaft and which can be fastened together with the tool on / in the instrument shaft. More precisely, the surgical tool, in particular the tool shaft and the bearing bushing, is designed to be inserted into a distal end of the instrument shaft. In particular, the bearing bushing is mounted axially fixedly on the bearing section of the tool shaft when not inserted into the surgical instrument. In other words, the bearing bushing is preferably at least axially fixedly connected to the bearing section of the tool shaft when the tool is present individually, i.e. when it is not inserted into the instrument shaft.The bearing bush preferably has a larger diameter than the entire tool shank proximal to the bearing bush, preferably than an entire section of the tool proximal to the bearing bush. In particular, the bearing bush has a larger diameter than the drive section of the tool shank. Furthermore, the entire bearing bush is preferably arranged distally of the drive section. The bearing bush preferably has an inner ring which is connected to the bearing section in a substantially axially and rotationally fixed manner. Further preferably, the bearing bush has an outer ring which is rotatable (and, apart from a bearing play, axially fixed) to the inner ring. The bearing coupling element is preferably provided on the outer ring, in particular on a radial outer surface of the outer ring. The tool preferably has a seal, in particular in the form of a cover disk, at a distal end of the bearing bush or distal to the bearing bush.This can, in particular, reduce or prevent the penetration of dirt and / or fluid into the bearing bush and the instrument shaft. Preferably, only the tool tip and, if applicable, a seal are arranged distally of the bearing bush. Preferably, apart from a seal, if applicable, no components are arranged distally of the bearing bush that directly interact with the instrument shaft located radially outside of it.

[0015] Such tools and instruments enable high rotational speeds at low temperatures, as well as precise positioning of the tool tip / head, which always has a constant projection beyond the distal end of the instrument shaft. The special tool design enables precise tool guidance, trouble-free operation, and optimized tool coupling in the instrument housing. Furthermore, the tool is particularly easy to assemble and disassemble.

[0016] The tool shaft preferably also has a flexibly flexible and torsionally rigid flex section, which is arranged between the bearing section and the drive section. This enables an angulation of the tool tip with respect to the tool shaft and the instrument shaft while simultaneously ensuring precise positioning of the tool and extremely smooth running. The flexible part or the flex section ensures that the tool can be operated both in a reversible position and in an angled position (e.g. 45°) and can transmit torque. For example, the flex section can be connected to the bearing section at its distal end, for example via a fork or receptacle of the bearing section. Alternatively or additionally, the flex section can be connected to the drive section at its proximal end, for example via a fork or receptacle of the drive section.A section of the bearing section that is thickened in the area of ​​the fork or holder can also serve as a radial shoulder for the bearing bush.

[0017] In particular, an angle of 30-60°, preferably at least 45°, of the tool tip relative to the tool shaft is provided. Furthermore, because the curvature of the flexible section is determined from the outside by an angle of the instrument shaft, only a small axial length is required for the angle.

[0018] Such a flexible section can be provided, for example, by a special braiding of individual strands. The flexible section can have a torque strand, in particular with multiple layers of alternating winding direction. This means that the flexible section can have a first sleeve made of individual strands or individual fibers wound in a first direction and a second sleeve (firmly connected to it) made of individual strands or individual fibers wound in a second direction. This allows for clockwise and counterclockwise rotation without the strand untwisting and self-destruction. In particular, the drive section and / or the bearing section are designed to be flexurally and torsionally rigid, for example, rod- or tubular. This enables particularly precise coupling to the drive of the instrument and particularly good bearing via the bearing bush.

[0019] Furthermore, the surgical tool is in particular a tool that is driven in a rotating manner, in particular a milling or drilling tool.

[0020] It is advantageous if the bearing bushing has a proximal end face that forms a stop surface for engagement with the instrument shaft, particularly in its distal shaft section. This makes it possible to precisely define the position of the tool tip relative to the instrument shaft, ensuring a constant projection of the tool tip beyond a distal end of the instrument shaft for all adjustable angles of the tool tip relative to the tool shaft. Furthermore, the stop surface provided proximally on the bearing bushing prevents a corresponding load from being transferred to the flexible section when the tool tip is loaded, which would then be compressed or subjected to excessive stress during operation.

[0021] The bearing coupling element preferably forms a radial recess or a radial projection on or in a peripheral wall of the bearing bush. For example, a radial recess can be provided in the form of a circumferential groove. A suitable counter-coupling element or a locking mechanism (for example with a locking body in the form of a ball pressure element) can be provided radially on the inside of the instrument shaft in order to engage with or lock the radial recess or the radial projection, for example in the manner of a click connection. This enables particularly quick and easy assembly and, in particular, simple determination of the position of the bearing bush on the instrument shaft in the axial direction. The housing of the bearing bush ensures safe and easy insertion of the tool into the shaft during the coupling process.

[0022] More preferably, the bearing bush provides a single-row, even more preferably a double-row, rolling bearing with one or two rolling bearings (a miniature rolling bearing / ball bearing). The rolling bearing can comprise deep groove ball bearings or angular contact ball bearings, the latter offering the advantages of better load-bearing capacity and simpler assembly. This makes it particularly suitable for high speeds while maintaining a low tool temperature. In the case of a double-row rolling bearing, particularly smooth running and a particularly low tool temperature are achieved, and the risk of the tool tipping can be significantly minimized. This makes the tool particularly stable, and the flex section is subjected to very little stress.

[0023] In particular, in a double-row rolling bearing arrangement, the bearing bush has a radially inner spacer bush and / or a preload element, which determine the axial position of the two rolling bearing rings relative to one another. This means that the spacer bush can be arranged between the individual bearings and bear against them, for example, on their inner rings, in order to position them relative to one another. The preload element can be a wave spring washer, for example, and can be inserted between one of the bearings and a housing section of the bearing bush. Thus, the preload element can preload the corresponding adjacent bearing outwards in the axial direction with respect to the other bearing. This allows component tolerances to be compensated, the service life of the bearings or bearing bush can be increased, and the noise level can be reduced.Preferably, the bearing bush, in particular on its distal side, can have a cover disk which protects a correspondingly adjacent one of the bearings from mechanical damage and, if applicable, from the penetration of a liquid (in the case of an embodiment as a sealing disk).

[0024] The bearing bush is preferably mounted in the axial direction between the bearing section and the distal tool tip, e.g., between a first circumferential step of the bearing section and a second circumferential step of the distal tool tip. For example, the distal tool tip can be screwed to the bearing section. For example, the distal tool tip can form an internal thread that is screwed onto an external thread of the bearing section. This eliminates the need for additional elements to fasten the bearing bush to the tool shank. Optionally, the bearing section can be connected (in one piece) to the tool tip. The bearing bush can be fastened to the bearing section using a screw nut or similar.

[0025] It has proven advantageous if the drive section forms at least one engagement section extending in the axial direction, in particular a profiled shaft section, such as a hexagonal profile. A section extending in the axial direction, in particular with a cross-sectional profile that is constant along the axial direction, enables longitudinal displacement between the drive section and the drive shaft, which can occur, for example, due to the angling of the flex section. A profiled shaft section is also particularly well suited to absorbing a drive torque. Thus, in the coupled state, the tool can be positively connected to a tube (the drive shaft), which can be driven by a motor in the instrument / handpiece / instrument handle.The tube can be firmly connected to the engagement holder, which, for example, has a hexagonal geometry, over which the entire tool can be rotated and, for example, a milling head can remove material.

[0026] Preferably, the length of the engagement section corresponds at least to a maximum displacement distance of a proximal end of the flexible section at its maximum curvature. Thus, at any degree of angulation of the tool tip relative to the tool shaft, an overlap and thus a torque transmission between the engagement section and an engagement receptacle of the drive shaft, with which the engagement section interacts, can be ensured. In other words, a displacement / change in length can occur in the proximal region of the tool. The reason for this is the fixation between the distal end of the instrument shaft and the tool via the bearing bush, as well as a changed tool guidance in the angled state and a resulting change in the bending line of the flexible section.Appropriate length compensation in the proximal area is achieved by the length (extension in the axial direction) of the driven engagement section / profile shaft section / hexagon. In other words, the engagement section and the engagement receptacle are designed such that they can be moved essentially freely relative to one another in the axial direction / without stopping. The resulting reduction in the driven length of the engagement section amounts to a few millimeters and can be taken into account in the overall length of the engagement section to ensure reliable torque transmission.

[0027] Advantageously, the drive section forms a proximal centering end, in particular a centering tip with beveled side walls or a beveled peripheral wall. This enables easy insertion of the drive section into the drive shaft, since the centering end can compensate for misalignments therebetween. More preferably, the centering end forms a profile section, in particular with a three-sided pyramid shape, which is designed for rotationally position-determined engagement with a counter-profile section of the surgical instrument. A profile section of the proximal centering end is to be understood as a section having a profile (i.e., a shape that is not continuously rotationally symmetrical) that is at least partially aligned in the axial direction.This ensures that the profile section can only be connected to a matching counter profile section in one (or a certain number of) specific rotational / turning positions.

[0028] Alternatively or additionally, the object underlying the present disclosure is achieved by a surgical instrument having an instrument shaft which is distally open and designed to receive a surgical tool according to one of the preceding claims. The instrument shaft has a distal instrument shaft section in which a counter-coupling element or a locking mechanism is provided, which is designed for releasable coupling to the bearing coupling element of the surgical tool. In particular, the locking mechanism is a spring-biased or pre-stressable locking mechanism. This means that it can have an engagement element which is connected to the distal instrument shaft section via a spring element and which is pre-stressable or can be pre-stressed by the spring element, in particular radially inward.Furthermore, the instrument shaft has a proximal instrument shaft portion which has a drive shaft designed for positive engagement with the drive portion of the surgical tool.

[0029] In particular, it is a surgical instrument or handpiece with a fully integrated rotating mechanism.

[0030] Preferably, the counter-coupling element / locking mechanism comprises a spring-mounted engagement element / locking body. Such a locking mechanism can be connected to the bearing bush in the manner of a click connection and thus provide tactile and / or audible feedback upon completion of the insertion of the tool into the instrument. This means that the tool is ready for use when the axial fixation of the tool has taken place at the end of the coupling process.

[0031] Further preferably, the distal instrument shaft section and the proximal instrument shaft section are angled relative to one another. In particular, the distal instrument shaft section and the proximal instrument shaft section are beveled on mutually facing end faces and are rotatable relative to one another to achieve an angling of the instrument shaft. Preferably, a gear train for rotating the distal instrument shaft section relative to the proximal instrument shaft section is arranged radially outside, in particular spaced apart from, the tool shaft and / or the drive shaft.

[0032] It has also proven advantageous if the drive shaft forms a distal centering receptacle, particularly in the form of a funnel with beveled side walls. This further improves centering / compensation of alignment errors when inserting the tool (the drive section) into the instrument (into the drive shaft). The centering receptacle preferably extends from a hollow shaft, initially radially outwards, and then, in a funnel-like manner, diagonally in the proximal and radially outwards direction. This ensures that the funnel geometry is at a radial distance from the drive section. Thus, a coupling area between the flexible section and the drive section, which may be thicker than the drive section, can be moved longitudinally in the area of ​​the funnel geometry / centering receptacle without it coming into contact with the funnel. This enables a longitudinally compact design of the tool and instrument.In other words, the funnel component is positioned / dimensioned in such a way that a proximal socket of the flex section has sufficient space to deflect and the tool is guided into the drive geometry / engagement receptacle during the coupling process.

[0033] An axial space is expediently formed in the proximal instrument shaft section distal to the drive shaft to ensure the longitudinal movement of the proximal socket / coupling area of ​​the flexible section with the drive section. For this purpose, it is advantageous if a drive train / gear train for angling the instrument shaft is formed radially outside or radially spaced from the tool shaft, for example, having a ring gear surrounding the axial space / axial space.

[0034] In particular, the entire drive shaft is arranged in the proximal instrument shaft section and optionally in a proximal handle of the surgical instrument. Furthermore, when the tool is fully mounted on the instrument, the entire bearing section can be arranged in the distal instrument shaft section and / or the entire drive section can be arranged in the proximal instrument shaft section.

[0035] Advantageously, the drive shaft forms a longitudinally extending engagement receptacle, in particular a profiled hollow shaft section, for engagement with the drive section or its engagement section. Preferably, a length of the engagement receptacle corresponds at least to a displacement distance of a proximal end of the flexible section at its maximum curvature. Preferably, a length of the engagement section of the tool and a length of the engagement receptacle of the instrument are coordinated such that they overlap even when the flexible section is maximally or minimally curved.

[0036] It is further preferred if a distal pin is accommodated in the drive shaft so as to be axially displaceable and rotationally fixed, said pin forming a counter-profile section at its distal end for rotationally position-determined engagement with the profile section of the surgical tool. The counter-profile section is designed to match the profile section in such a way that it can only (fully) engage with the profile section in one or more specific orientations. For example, the counter-profile section is a negative form of the profile section or has contact surfaces distributed in the circumferential direction for contact with surfaces of the profile section. If the rotationally symmetrical tool is coupled in the instrument shaft, it is brought into the correct position (rotational position) via such a pin. In particular, it is advantageous to hold the tool on the bearing bush, since the tool shaft can then rotate freely.Due to the interaction / guidance of the profile section and the counter profile section, the tool rotates into the correct position (is correctly aligned) so that, for example, the engagement section (e.g., the hexagon profile) is aligned to match the engagement receptacle (e.g., a hexagon socket profile). This simplifies the coupling process and brings the tool (especially in the area of ​​the funnel) into the correct position, largely preventing misalignment of the engagement section with the engagement receptacle and jamming between them.

[0037] A spring element can expediently be provided in the drive shaft proximal to the distal pin, which is adapted to preload the distal pin in the distal direction. If the tool is not coupled to the instrument, this can ensure that the distal pin or a distal end thereof is held in the region of the funnel or even further distally in order to enable early alignment of the engagement section with the engagement receptacle. The spring element thus guides the distal pin. The spring / spring element has, in particular, a very low spring rate (is a very soft spring) in order to enable easy insertion of the tool and also not to place excessive strain on the flexible section. The spring can be a mechanical spring, for example a coil spring, or for example a pneumatic spring.

[0038] Furthermore, a proximal pin can preferably be provided proximal to the spring element, which pin is received (in particular in a rotationally fixed manner) in the drive shaft and supports the spring element proximally. More preferably, the distal pin, the proximal pin and the spring element form a coupling aid and are connected to one another in a rotationally fixed manner (e.g. welded / glued). The proximal pin and / or the distal pin can have a tool holder, e.g. an adjustment slot, at its / their respective proximal end. The tool holder(s) is / are accessible at least during assembly of the instrument, for example using a screwdriver. Thus, this tool holder(s) is / are provided for adjusting a rotational alignment of the counter profile section relative to the engagement holder of the drive shaft or to the engagement section of the tool.

[0039] In particular, the surgical instrument is a hand instrument having a proximal handle element for gripping by a user, from which the instrument shaft extends distally.

[0040] Alternatively or additionally, the object underlying the present disclosure is achieved by a system comprising a surgical tool described above and a surgical instrument described above.

[0041] Character description

[0042] The present invention is described below using a preferred embodiment. However, these are merely illustrative in nature and are not intended to limit the scope of the present invention.

[0043] Fig. 1 shows a surgical tool according to a first embodiment of the present disclosure at the bottom and the surgical tool without a bearing bush mounted thereon at the top.

[0044] Fig. 2 shows a detailed view of a flex section of the surgical tool shown in Fig. 1.

[0045] Fig. 3 shows a bearing bushing of the surgical tool shown in Fig. 1. Fig. 4 shows a longitudinal section through the surgical tool shown in Fig. 1.

[0046] Fig. 5 shows the surgical tool shown in Fig. 1 mounted in a surgical instrument according to an embodiment of the present disclosure, in a straight-aligned state (top) and in an angled state (bottom).

[0047] Fig. 6 shows a view of a proximal instrument shaft portion of the instrument shown in Fig. 5.

[0048] Fig. 7 shows a coupling aid of the instrument shown in Fig. 5 in a state in which the tool shown in Fig. 1 is not mounted (top) and in a state in which the tool is mounted (bottom).

[0049] Fig. 8 illustrates a coupling process between the tool shown in Fig. 1 and the instrument shown in Fig. 5.

[0050] Fig. 9 illustrates a setting of the clutch aid shown in Fig. 7.

[0051] Fig. 1 shows on the left a surgical tool 1 according to a first embodiment of the present disclosure. The tool 1 has a distal tool tip 2, e.g. a milling head. A tool shank extends proximally from the tool tip 2. The tool shank has a bearing section 3 connected (directly) to the tool tip, which in turn is connected (directly) to a more proximal flex section 4, which is connected (directly) to a most proximal drive section 5. The drive section 5 has an engagement section 6, which is exemplary designed as a hexagonal profile. A proximal end of the drive section 5 forms a centering end 7, more precisely, a centering tip with a profile section in the shape of a longitudinally extending pyramid. The bearing section 3 carries a bearing bush 8, which is described in more detail below with reference to Fig. 3. At the top of Fig.1, the surgical tool is shown without the bearing bushing 8. It can be seen that the bearing section 3 forms a section with a reduced diameter, which is delimited proximally by a radial step of the bearing section 3 and distally by a radial projection of a proximal end of the tool tip 2. The bearing bushing 8 is attached to the reduced diameter section on the right in the illustration.

[0052] Fig. 2 shows a detailed view of a flex section 4 of the surgical tool 1 shown in Fig. 1. The flex section 4 has two radial layers. A radially inner layer is formed by fibers / strands wound around a longitudinal axis of the tool 1 in a first winding direction. A radially outer layer is formed by fibers / strands wound around the longitudinal axis of the tool 1 in a second winding direction, opposite to the first winding direction.

[0053] Fig. 3 shows a bearing bush 8 of the surgical tool 1 shown in Fig. 1. The bearing bush 8 has a housing 9, which forms a radial outer wall of the bearing bush 8. A circumferential groove is formed in the radial outer wall as an engagement element or as a bearing coupling element 10. At each end of the housing 9, a ball groove bearing 11 (in short: bearing) is mounted in the housing 9. One of the bearings 11 (the proximally arranged one) is fixedly connected to the housing 9, while the other bearing 11 (the distally arranged one) is floatingly mounted therein. Between a housing shoulder of the housing 9 and the floatingly mounted bearing 11, a preloading element 12 in the form of a wave spring washer is arranged, which preloads the corresponding bearing 11, in particular its outer ring, in the axial direction outwards (in the assembled state towards the tool tip).Between the bearings 11, in particular adjacent to their inner rings, a spacer bushing 13 is provided, which determines an axial position of the bearings 11 relative to one another. Opposite the spacer bushing 13, on an outer side of the bearing bush 8, a cover disk 14 is mounted on the bearing 11 aligned distally on the tool 1, which cover disk covers and / or seals a gap between the inner and outer rings of the respective bearing 11. Fig. 4 shows a longitudinal sectional view through the surgical tool 1 shown in Fig. 1. It can be seen that the ends of the flex section 4 are each received in receptacles formed at the proximal end of the bearing section 3 and at the distal end of the drive section 5, respectively. It can also be seen that the bearing bush 8 is fixed in its position in the axial direction by radial shoulders formed by the tool tip 2 and the bearing section 3, respectively.

[0054] Fig. 5 shows the surgical tool 1 shown in Fig. 1, which is mounted in a surgical instrument 15 according to an embodiment of the present disclosure, in a straightened / extended state (top) and in an angled state (bottom). The instrument 15 has a proximal (instrument) shaft section 16 and a distal (instrument) shaft section 17, whose mutually facing end faces extend obliquely with respect to the longitudinal axis and are connected to one another via a rotation mechanism such that rotating the proximal and distal shaft sections 16, 17 relative to one another results in angling thereof, as shown in the lower illustration.

[0055] The tool 1 is axially fixed in position relative to the instrument 15 via the bearing bush 8. The bearing bush 8 or the proximal deep groove ball bearing 11 forms a stop surface on its proximal end face, with which the bearing bush 8 rests against a housing of the distal shaft section 17. The housing of the distal shaft section 17 further accommodates a locking mechanism with a spring-loaded slide 18, which preloads a locking body 19 radially inward for engagement in the engagement element or the bearing coupling element 10 or the groove of the bearing bush 8. The engagement of the locking body 19 in the engagement element or the bearing coupling element 10 also fixes the position of the bearing bush 8 relative to the distal shaft section 17 in the distal direction.

[0056] The flexible section 4 extends from the bearing section 3 to the drive section 5 through the instrument shaft 16, 17 and, if necessary (see lower illustration), follows an angle between the proximal and distal shaft sections 16, 17. A proximal end of the flexible section 4 is connected to the drive section 5 in the region of an axial space / axial space (for example, within a ring gear of the rotary mechanism). The drive section 5, in particular its engagement section 6, is received in a form-fitting and axially displaceable manner in an engagement receptacle 21 of the drive shaft 20. The engagement receptacle 21 is designed to complement the engagement section 6, for example, in the form of a hexagon socket profile.

[0057] A distal end of the drive shaft 20 forms a funnel-shaped centering receptacle 22, which initially extends radially outward to provide a radial distance between one of the engagement receptacles 21 and the drive section 5, so that a radially thickened coupling region, at which the flexible section 4 and the drive section 5 are connected, is displaceable within the centering receptacle 22. The centering receptacle 22 then extends radially widening in the distal direction to form an insertion aid for the drive section 5 during assembly of the tool 1.

[0058] As can be seen when comparing the lower and upper illustrations, when the instrument 15 is bent, the axial position of the tool 1 in the distal shaft section 17 remains constant. However, due to the bending of the flexible section 4 or its slipping in the radial direction during the bent, a proximal end of the tool shifts. In particular, the coupling area shifts within the centering recess 22 and the axial space, and the engagement section 6 of the drive section 5 shifts within the engagement recess 21 of the drive shaft 22.

[0059] Fig. 6 shows a view of a proximal instrument shaft section 16 of the instrument shown in Fig. 5, in which the tool 1 is not mounted. Thus, the engagement receptacle 21 of the drive shaft 22, designed here as an exemplary hexagon socket, can be seen.

[0060] Fig. 7 shows a coupling aid of the instrument shown in Fig. 5 in a state in which the tool shown in Fig. 1 is not mounted (top) and in a state in which the tool is mounted (bottom). The coupling aid has a distal pin 23, a spring element 24 mounted or fastened in a rotationally fixed manner at its proximal end, and a proximal pin 25, which in turn is mounted or fastened in a rotationally fixed manner at its proximal end. The distal and proximal pins 23, 25 as well as the spring element 24 are received in the drive shaft 20. The drive shaft 20 can be made up of several parts. The distal pin 23 is arranged so as to be rotationally fixed and axially displaceable relative to the drive shaft 20. Preferably, the proximal pin 25 and the spring element 24 are also arranged so as to be rotationally fixed therein. The spring element 24 preloads the distal pin 23 in the distal direction.As a result, its distal end protrudes from the drive shaft 20, as explained in more detail below, when the tool 1 is not mounted and the spring element 24 is not compressed, as can be seen in the upper illustration in Fig. 7. When the tool 1 is mounted, the distal pin 23 is pushed back in the proximal direction by the drive section 5 of the tool 1 and the spring element 24 is compressed, as can be seen in the lower illustration in Fig. 7.

[0061] Fig. 8 illustrates a coupling process between the tool shown in Fig. 1 and the instrument shown in Fig. 5. In the uppermost illustration (labeled "A"), the tool shaft is inserted into the instrument shaft, but the bearing bush 8 is still outside the instrument shaft. The centering end 7 of the drive section 5 is inserted into the funnel-shaped centering receptacle 22 and is centered by it or guided to the engagement receptacle 21. At the entrance to the engagement receptacle 21, the distal end of the distal pin 23 is arranged, which forms a counter-profile section 26 for receiving and aligning the profile section 7 of the drive section 5. The counter-profile section is aligned with the engagement receptacle 21 of the drive shaft 20 in such a way that when the profile section 7 is inserted into the counter-profile section 26, as shown in illustration "B", the engagement section 6 of the drive section 5 engages the engagement receptacle 21 of the drive shaft.

[0062] 20 is aligned.

[0063] Subsequently, as shown in illustration “C” in Fig. 7, the drive section 5 pushes the distal pin 23 in the proximal direction and the engagement section 6 of the drive section of the tool 1 is inserted into the engagement receptacle

[0064] 21 of the drive shaft 20 of the instrument 15. At the same time, the bearing bush 8 slides into the distal shaft section 17 of the instrument 15. In the lower illustration "D", the tool 2 is finally fully inserted into the instrument 15. The bearing bush 8 comes to rest in the proximal direction on the housing of the distal shaft section 17 and the locking body 19 is secured in the engagement element or bearing coupling element 10 of the bearing bush 8. The tool 1 is thus fully mounted in the instrument 15.

[0065] Fig. 9 illustrates an adjustment of the coupling aid shown in Fig. 7. More specifically, a proximal end of the proximal pin 25 is shown, on which a slot-shaped tool holder 27 is provided, shown here as an example. An adjustment tool 28 can be inserted into the tool holder during assembly of the instrument in order to align the proximal pin 25, together with the spring element 24 connected thereto in a rotationally fixed manner, and the distal pin 23, more precisely its counter-profile section, with the engagement receptacle 21 of the drive shaft 20. If necessary, a tool holder for adjusting the distal pin 23 can also be provided directly on the distal pin 23.

[0066] List of reference symbols

[0067] Tool

[0068] Tool tip / heads

[0069] Storage section

[0070] Flex section

[0071] Drive section

[0072] Intervention section

[0073] Centering / tip / profile section

[0074] Bearing bush

[0075] Bearing bush housing

[0076] Bearing coupling element / engagement element / groove

[0077] Bearings / deep groove ball bearings

[0078] Preload element / wave spring washer

[0079] spacer bushing

[0080] Cover plate

[0081] instrument

[0082] Proximal (instrument) shaft section

[0083] Distal (instrument) shaft section

[0084] Locking slide (locking mechanism)

[0085] Locking body / spring-loaded engagement element (locking mechanism)

[0086] drive shaft

[0087] Intervention recording

[0088] Centering mount

[0089] Distal pin

[0090] spring element

[0091] Proximal pin

[0092] Counter profile section

[0093] Tool holder

Claims

Claims 1. Surgical tool (1) designed to be inserted into an instrument shaft (16, 17) of a surgical instrument (15), comprising a distal tool tip (2), a tool shaft (3, 4, 5) extending proximal from the distal tool tip (2) and comprising a distal bearing section (3) and a proximal drive section (5) designed to engage positively with a drive shaft (20) of the surgical instrument (15), and a bearing bushing (8) which is axially fixed on the distal bearing section (3) in a state not inserted into the surgical instrument (15) and comprises a bearing coupling element (10) for detachable coupling with an instrument shaft (16, 17) of the surgical instrument (15).

2. Surgical tool (1) according to claim 1, wherein the tool shaft (3, 4, 5) further comprises a bend-flexible and torsionally stiff flex section (4) which is arranged between the bearing section (3) and the drive section (5).

3. Surgical instrument (1 ) according to one of claims 1 and 2, wherein the bearing bushing (8) has a proximal end face which forms a stop surface for placement in the instrument shaft (16, 17).

4. Surgical instrument (1) according to one of claims 1 to 3, wherein the drive section (5) forms at least one engagement section (6) extending in the axial direction, in particular a profile shaft section.

5. Surgical tool (1 ) according to claim 4, wherein a length of the engagement section (6) corresponds to at least a maximum axial displacement distance of a proximal end of tool shaft (3, 4, 5) at its maximum curvature.

6. Surgical instrument (1) according to any one of claims 1 to 5, wherein the drive section (5) forms a proximal centering element (7), in particular a centering tip with beveled side walls.

7. Surgical tool (1) according to claim 6, wherein the centering element (7) forms a profile section, in particular with a pyramidal profile, which is designed for rotationally determined intervention with a counter-profile section (26) of the surgical instrument (15), in particular a distal pin (23) of the instrument (15).

8. Surgical instrument (15) comprising an instrument shaft (16, 17) which is distally open and designed to receive a surgical tool (1) according to one of the preceding claims, a distal instrument shaft section (17) in which a spring-loaded or pre-loadable locking mechanism (18, 19) is provided, which is designed for releasable coupling with the bearing coupling element (10) of the surgical tool (1), and a proximal instrument shaft section (16) which has a drive shaft (20) designed for positive engagement with the drive section (5) of the surgical tool.

9. Surgical instrument (15) according to claim 8, wherein the drive shaft (20) forms a distal centering receptacle (22), in particular in the form of a funnel with beveled side walls.

10. Surgical instrument (15) according to one of claims 8 and 9, wherein an axial space is formed in the proximal instrument shaft section (16) distal to the drive shaft (20).

11. Surgical instrument (15) according to one of claims 8 to 10, wherein the drive shaft (20) forms a longitudinally extending engagement receptacle (21), in particular a profiled hollow shaft section, for engagement with the drive section (5).

12. Surgical instrument (15) according to one of claims 8 to 11, wherein a distal pin (23) is axially displaceable and rotationally fixed in the drive shaft (20), which at its distal end forms a counter-profile section (26) for rotationally determined engagement with the profile section (7) of the surgical tool (1).

13. Surgical instrument () according to one of claims 8 to 12, wherein a spring element (24) is provided in the drive shaft (20) proximal to the distal pin (23), which is adapted to pre-tension the distal pin (23) in the distal direction.

14. Surgical instrument (15) according to one of claims 8 to 13, wherein a proximal pin (25) is provided proximal to the spring element (24), which is received in the drive shaft (20) and is rotationally fixed to the distal pin (23), and which has a tool receptacle (27) at its proximal end for adjusting a rotational alignment of the counter profile (26) with respect to the drive shaft (20).

15. System comprising a surgical tool (1) according to one of claims 1 to 7 and a surgical instrument (15) according to one of claims 8 to 14.

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