MEDICAL DECOUPLING INSTRUMENT

Description

[0001] The present invention relates to a medical decoupling instrument for decoupling a medical insertion instrument from a pedicle screw. State of the art

[0002] Pedicle screws are primarily used for dorsal stabilization of the spine in cases of fractures, tumors, inflammation, deformities, and degenerative instabilities using transpedicular screw fixation. Pedicle screws are placed in the pedicles of adjacent vertebrae, creating an angularly stable connection between the axially stacked pedicle screws and an axially extending longitudinal member / rod. The pedicle screws and longitudinal members form a vertebral stabilization system.

[0003] For this purpose, a pedicle screw typically has an axial, shaft-like external threaded section, to which a so-called tulip or receiving sleeve is attached on the screw head side. This forms a U-shaped slotted / tunneled receiving sleeve with an internal thread, with the two radially opposite longitudinal slots each defining a slot gap of a predetermined width. The longitudinal support / rod is inserted transversely into the parallel longitudinal slots and secured by a locking element, for example, in the form of a grub screw, threaded nut, or setscrew, which is screwed into the internal thread.

[0004] There are basically two basic types of pedicle screws: monoaxial and polyaxial pedicle screws. In the case of a monoaxial pedicle screw, the externally threaded section / shaft and the tulip / receiving sleeve are formed as a single piece. A polyaxial pedicle screw, on the other hand, has an externally threaded shaft manufactured as a separate component with a usually spherical or (semi-)spherical screw head, which is encompassed by the receiving sleeve / tulip in a relatively pivotable manner and, at the same time, is engaged behind in the transition area between the head and shaft. In this way, after the externally threaded shaft has been countersunk into the pedicle canal of a vertebra, the receiving sleeve / tulip can be pivoted and / or rotated relative to it in order to achieve a desired position and orientation essentially independent of the orientation of the shaft. The undercut prevents the receiving sleeve / tulip from being pulled off the shaft head.

[0005] Pedicle screws are inserted or anchored by a surgeon into the pedicle canal of a vertebra. The surgeon uses, among other things, a so-called insertion instrument, also referred to as a "downtube." The insertion instrument may, for example, have two coupling arms at its distal end. On the radially inner side of these, locking structures, such as locking lugs, are formed. These can be engaged with corresponding counter-locking structures formed on the receiving sleeve / tulip of the pedicle screw.

[0006] If the surgeon wishes to decouple the insertion instrument from the pedicle screw after the pedicle screw has been screwed / anchored, a decoupling instrument, also known as a "removal key," is required. The decoupling instrument is generally inserted into the insertion instrument and spreads the insertion instrument, particularly the coupling arms of the insertion instrument (defined elastic deformation), thus enabling the decoupling.

[0007] From the state of the art (see Fig. 1 to Fig. 4 ), for example, a decoupling instrument is known which can be inserted into an insertion instrument. Fig. 4 shows, for example, an upper section of the insertion instrument into which the decoupling instrument is inserted.

[0008] The decoupling instrument known from the state of the art (see in particular Fig. 1 to 3) basically has a hollow cylinder / sleeve-like component with a proximal handle section. A cylindrical rod is accommodated in the hollow cylinder / sleeve-like component, which has an engagement element at its distal end, which is intended to engage positively with a pedicle screw (see especially the lower section in Fig. 2). At the proximal end of the cylindrical rod, an engagement pin is attached / fastened, which is received in a slotted slot provided in the hollow cylindrical / sleeve-like component. When the cylindrical rod is positively engaged with the pedicle screw, the engagement pin allows a rotation of the hollow cylindrical / sleeve-like component by approximately 90°. The slotted slot or slot extends in the circumferential direction of the hollow cylindrical / sleeve-like component. At the distal end of the hollow cylindrical / sleeve-like component, an oval engagement section is provided (see especially the upper section in Fig. 2If the hollow cylindrical / sleeve-like component is rotated by approximately 90° from its initial / zero position, the oval engagement section of the decoupling instrument can decouple the insertion instrument, particularly by spreading the coupling arms of the insertion instrument. The decoupling instrument can generally be used for both coupling and decoupling pedicle screws.

[0009] The state of the art, which consists of the Fig. 1 to 4 This approach has the fundamental disadvantage that the hollow cylinder / sleeve-like component and the cylindrical rod must be manually aligned before inserting the decoupling instrument into the insertion instrument. Furthermore, the positive fit at the distal end between the pedicle screw and the decoupling instrument can complicate decoupling.

[0010] US 2014 / 371756 A1 discloses a medical insertion instrument for inserting a pedicle screw with integrated decoupling functionality. The insertion instrument has an engaging end at the distal end of a shaft, which can be engaged with a recess provided in a pedicle screw. Proximal to the engaging end, the insertion instrument has an engaging element with flexible spring elements that can be engaged with the tulip of the pedicle screw. A spring is provided between a proximal end surface of the engaging element and a sleeve. The sleeve can be pressed against a shoulder of the pedicle screw. In this state, the insertion instrument can be decoupled from the pedicle screw or withdrawn.

[0011] US 2009 / 234395 A1 discloses a medical instrument in which, when a lever is actuated, a pin moves forward in an inclined or curved slot, causing a rotational movement of the actuating elements. This allows a pedicle screw to be held firmly in place.

[0012] US 2014 / 222081 A1 discloses a retractor and a reducer, the reducer having a spiral-shaped guide. A rod is guided to a pedicle screw via a rotating movement of the reducer. Brief description of the invention

[0013] Against this background, the object of the present invention is to avoid or at least mitigate the disadvantages of the prior art. In particular, a medical decoupling instrument for decoupling a medical insertion instrument from a pedicle screw is to be provided, which can be easily coupled to the medical insertion instrument and provides secure decoupling (in particular, the medical insertion instrument is elastically deformed in a defined manner).

[0014] This object is achieved by a medical decoupling instrument according to claim 1 and a medical device according to claim 7. Advantageous embodiments and further developments are claimed in the subclaims and / or are explained below. In the following, the terms "proximal" and "distal" are used in such a way that "proximal" means closer to the user / surgeon, and "distal" means farther from the user / surgeon.

[0015] The invention initially relates to a medical decoupling instrument for decoupling a medical insertion instrument from a pedicle screw, in particular by spreading the medical insertion instrument, with: a shaft / rod and a sleeve arranged around a (in particular cylindrical) section of the shaft / rod, which sleeve is designed for defined, in particular rotation-proof, coupling to the medical insertion instrument, wherein the shaft / rod (for decoupling the medical insertion instrument from the pedicle screw) is rotatable with respect to the sleeve, and wherein the medical decoupling instrument is designed to move the shaft / rod and the sleeve independently and automatically into a defined starting position / zero position.

[0016] The medical decoupling instrument according to the invention thus provides a defined zero position / starting position, and preferably no manual alignment of the shaft and sleeve is necessary. In other words, the shaft and sleeve of the medical decoupling instrument according to the invention are automatically aligned with each other for insertion / introduction into the medical insertion instrument.

[0017] The medical decoupling instrument further comprises a spring, in particular a spiral spring / compression spring, which is arranged between a support surface provided on the shaft and the sleeve and is configured to move the shaft and sleeve into the defined starting position / zero position via its spring force. In particular, the sleeve has a support surface for the spring at its distal end.

[0018] The shaft has a pin-shaped / pin-shaped projection at the portion around which the sleeve is arranged, the sleeve has a slotted slot / slot, and the pin-shaped projection of the shaft is received / arranged in the slotted slot of the sleeve in such a way that the slotted slot defines a rotation range / rotatability (angular range) of the shaft with respect to the sleeve.

[0019] The gate extends obliquely, i.e., it extends both in the circumferential direction and in the axial direction of the sleeve, so that a first end of the gate is arranged closer to a distal end of the sleeve than a second end of the gate.

[0020] It is particularly advantageous if, in the defined starting position, the pin-shaped projection of the shaft is pressed against the first end of the guide by the spring. In other words, the spring preferably applies a compressive force to the sleeve in such a way that the pin-shaped projection / pin / pin of the shaft is in the original position / starting position / zero position at the first end of the guide.

[0021] Advantageously, the sleeve's slotted guide allows approximately a 90° rotation of the shaft. In other words, the slotted guide extends approximately 90° from the first end to the second end in the circumferential direction.

[0022] A preferred embodiment is characterized in that the slotted guide has a recess / notch / trough at its second end (in the axial direction toward the distal end of the sleeve) so that the pin-shaped projection of the rod can be pressed into the recess via the spring. This allows a user / surgeon to receive tactile feedback when the medical insertion instrument is decoupled from the pedicle screw.

[0023] It is expedient if the sleeve has pin-shaped / pin-shaped projections for defined coupling to the medical insertion instrument, which projections are in particular diametrically opposite and extend radially outwards.

[0024] The pin-shaped projections are preferably designed such that they can be brought into engagement with the medical insertion instrument in such a way that the sleeve is held in the medical insertion instrument in a circumferentially rotationally secure manner.

[0025] Furthermore, it is advantageous if the shaft has a proximal engagement portion which is cylindrical with a non-circular cross-section or oval-cylindrical in shape and is in particular configured to be engaged with / spread open the medical insertion instrument for torque transmission.

[0026] Preferably, a portion of the shaft has a pressure piece configured to generate / apply a compressive force radially outward, in particular to press against the medical insertion instrument. In particular, the pressure piece is designed or configured such that it can exert a compressive force radially outward against the medical insertion instrument, thereby preventing the medical decoupling instrument from accidentally slipping out.

[0027] Advantageously, the shaft has a proximal gripping portion that is substantially cylindrical in shape with a round / circular or non-circular cross-section. Preferably, the proximal gripping portion is grooved or has a plurality of elongated recesses / depressions extending in the axial direction, which are particularly evenly spaced / distributed in the circumferential direction, for improved gripping (and twisting) of the shaft by a user / surgeon.

[0028] Preferably, a first cylindrical section adjoins the proximal grip section, which is provided at a proximal end of the shaft, in the axial direction. The first cylindrical section of the shaft is in particular the section of the shaft around which the hollow cylindrical sleeve is arranged, and thus the section of the shaft which has the radially outwardly extending pin-shaped / cylindrical projection. The first cylindrical section of the shaft preferably has a round / circular cross-section. The pin-shaped projection of the shaft arranged on the first cylindrical section is preferably received in the slotted guide of the sleeve.

[0029] It is advantageous if a second cylindrical section of the shaft adjoins the first cylindrical section of the shaft in the axial direction. The second cylindrical section has, in particular, a round / circular cross-section. Preferably, a diameter of the second cylindrical section is larger than a diameter of the first cylindrical section. The support surface for the spring is advantageously provided / formed at a proximal end of the second cylindrical section. The pressure piece is preferably provided on the second cylindrical section of the shaft.

[0030] It is expedient if the second cylindrical section is adjoined in the axial direction by a third cylindrical section, which in particular has a round / circular cross-section and whose diameter is preferably smaller than the diameter of the second cylindrical section. This section does not necessarily have to be round, as long as the diameter / greatest width is not larger than the diameter of the second cylindrical section at any point.

[0031] Advantageously, the third cylindrical section is adjoined in the axial direction by the distal engagement section, which is provided / arranged at a distal end of the shaft.

[0032] Furthermore, the invention relates to a medical device comprising at least the above-described medical decoupling instrument and a medical insertion instrument.

[0033] The medical decoupling instrument is preferably designed to decouple the medical insertion instrument from the pedicle screw.

[0034] The decoupling is advantageously realized in that the medical decoupling instrument is configured to decouple the medical insertion instrument, in particular two diametrically opposed coupling arms of the insertion instrument extending parallel in the axial direction from a pedicle screw.

[0035] Preferably, the coupling arms of the insertion instrument each have a locking structure at their distal ends, which can be brought into engagement with a counter-locking structure which is formed on a receiving sleeve / tulip of a polyaxial or monoaxial pedicle screw.

[0036] It is expedient if the non-circular, distal engagement section of the medical decoupling instrument is designed to be brought into engagement with the coupling arms of the medical insertion instrument by twisting the shaft, in particular to decouple the coupling arms from the pedicle screw.

[0037] It is further advantageous if the peg-shaped projections of the sleeve are accommodated in the medical insertion instrument in a rotationally secure manner. For this purpose, the medical insertion instrument preferably has two diametrically opposed, axially extending V-shaped or U-shaped recesses at its proximal end, which accommodate the peg-shaped projections of the sleeve and hold them in a rotationally secure manner.

[0038] In other words, the invention relates to a (medical) decoupling instrument ("Removal Key") which contains a shaft, a sleeve and a (compression) spring mechanism.

[0039] The shaft has a pin / tenon, the sleeve has a slot / oblong hole and the pin / tenon of the shaft is received in the slot / oblong hole of the sleeve in such a way that the sleeve and shaft can be rotated relative to each other.

[0040] The shaft has a non-circular shape at its distal end, by means of which a (medical) insertion instrument ("downtube") can be spread to decouple the insertion instrument from a pedicle screw.

[0041] In addition, the shaft contains a pressure piece or a locking mechanism that holds the decoupling instrument in the insertion instrument.

[0042] The spring mechanism is arranged between the shaft and the sleeve in such a way that it ensures that the sleeve is always / automatically / automatically / in a zero position / defined starting position, so that the decoupling instrument can be inserted into the insertion instrument without prior manual turning / alignment.

[0043] The sleeve's slot allows the shaft to be rotated at a predefined angle, preferably approximately 90° clockwise, and can provide tactile feedback for uncoupling / spreading the insertion instrument via a small recess at one end of the slot. However, this recess is not essential for the slot's function.

[0044] Unintentional slipping of the decoupling instrument from the insertion instrument is prevented by the pressure piece or the locking mechanism, the recess in the slotted guide, and the contact between the decoupling instrument and the insertion instrument at the distal end.

[0045] To decouple the two instruments (decoupling instrument and insertion instrument), the decoupling instrument (its shaft) can be turned back, preferably by 90° counterclockwise (assisted by the spring force), so that the sleeve is again in the zero position / defined starting position for the next application.

[0046] This provides a decoupling instrument that provides a defined zero position and automatic alignment, does not require a positive fit between itself and the implant / pedicle screw, and preferably also provides tactile feedback for decoupling. A defined opening of the insertion instrument is ensured by the guide and the instrument alignment (alignment of shaft and sleeve) achieved by the (compression) spring. Short description of the characters

[0047] The invention is further explained below with the aid of figures. They show: Fig. 1 is a sectional view of a decoupling instrument known from the prior art; Fig. 2 is an isometric detailed view of a lower portion of the decoupling instrument of Fig. 1 ; Fig. 3 an isometric detailed view of an upper portion of the decoupling instrument of Fig. 1; Fig. 4 an isometric view of the decoupling instrument inserted into an insertion instrument of Fig. 1 ; Fig. 5 an isometric view of the medical device according to the invention comprising the decoupling instrument according to the invention and an insertion instrument; Fig. 6 an isometric view of the decoupling instrument according to the invention; Fig. 7 a first isometric detailed view of the decoupling instrument of Fig. 5 ; and Fig. 8 a second isometric detailed view of the decoupling instrument of Fig. 5 . Detailed description

[0048] The figures are merely schematic and serve solely to clarify the invention. Identical elements are designated by the same reference numerals.

[0049] Fig. 5 shows a medical device 2, which comprises (among other things) a medical decoupling instrument 4 and a medical insertion instrument 6.

[0050] The insertion instrument 6 has a main body 8. This forms an upper receiving section 10, among other things for the decoupling instrument 4. In the area of ​​the upper receiving section 10, the insertion instrument 6 has two V-shaped and U-shaped recesses 12 extending in the axial direction, which are designed to receive corresponding engagement structures provided on the decoupling instrument 4. Furthermore, the insertion instrument 6 has an inner (internal) threaded section 14 in the area of ​​the upper receiving section 10, which is designed to receive, in particular for screwing in, another instrument (not shown) of the medical device 2. For example, the inner threaded section 14 can accommodate a so-called insert pusher, which serves to fix a polyaxiality in a polyaxial pedicle screw (by pressing on an "insert").

[0051] Two diametrically opposed coupling arms 16, extending parallel in the axial direction, adjoin the upper receiving section 10 of the main body 8. The coupling arms 16 have locking structures at their distal ends, in particular locking lugs 18, which can generally be brought into engagement with counter-locking structures formed on a receiving sleeve / tulip of a polyaxial or monoaxial pedicle screw (not shown). The insertion instrument 6 further comprises a locking sleeve 20, which is arranged around the main body 8 in a transition region 22 between the upper receiving section 10 and the coupling arms 16.

[0052] The insertion instrument 6 is fundamentally configured to receive a pedicle screw, in particular a receiving sleeve / tulip of the pedicle screw, on its locking lugs 18. In a first release position of the locking sleeve 20, the coupling arms 16 have a suitable elasticity / flexibility to receive the pedicle screw, in particular the counter-locking structures of the pedicle screw, via their locking lugs 18. By rotating the locking sleeve 20 from the first release position to a second locking position, the main body 8 is pulled axially upward with respect to the locking sleeve 20. As a result, the coupling arms 16 are fixed by the locking sleeve 20, so that the pedicle screw is held firmly and securely by the insertion instrument 6.

[0053] If a surgeon / user wishes to decouple the insertion instrument 6 from the pedicle screw after the pedicle screw has been screwed / anchored, they must move the locking sleeve 20 from the second locking position to the first release position (by rotating the locking sleeve 20). Furthermore, the surgeon / user inserts the decoupling instrument 4 into the insertion instrument 6. Using the decoupling instrument, the coupling arms 16 of the insertion instrument 6 can be spread / pushed radially outward, thereby detaching the pedicle screw from the insertion instrument 6.

[0054] The medical decoupling instrument 4 according to the invention is in Fig. 6 , Fig. 7 and Fig. 8 presented in more detail.

[0055] The decoupling instrument 4 basically comprises a shaft / rod 24, a sleeve 26 and a spring 28.

[0056] The shaft 24 has a proximal grip portion 30 at its proximal end. In the preferred example shown, the proximal grip portion 30 is oval-cylindrical (cylindrical shape with an oval cross-section) and has a plurality of axially extending, circumferentially evenly spaced / distributed elongated recesses 32, which serve to improve the gripping of the shaft 24 by a user / surgeon.

[0057] A first cylindrical section 34 with a round / circular cross-section adjoins the proximal handle section 30 in the axial direction of the shaft 24. The first cylindrical section 34 has a pin-shaped projection 36 extending radially outward.

[0058] Adjoining the first cylindrical section 34 in the axial direction of the shaft 24 is a second cylindrical section 38 with a round / circular cross-section. The second cylindrical section 38 has a larger diameter than the first cylindrical section 34. A pressure piece or locking mechanism 40 is provided / arranged on the second cylindrical section 38. The pressure piece 40 generates a compressive force radially outward and can thus press against the insertion instrument 6, preventing the decoupling instrument 4 from accidentally slipping out. Another locking mechanism can also prevent the decoupling instrument 4 from accidentally slipping out.

[0059] A third cylindrical section 42, preferably with a round / circular cross-section, adjoins the second cylindrical section 38 in the axial direction of the shaft 24. The third cylindrical section 42 has a diameter equal to or smaller than that of the second cylindrical section 38.

[0060] Adjoining the third cylindrical portion 42 in the axial direction of the shaft 24 is a distal engagement portion 43, which forms the distal end of the shaft 24. The distal engagement portion 43 is cylindrical with a non-circular cross-section.

[0061] The sleeve 26 of the decoupling instrument 4 is basically hollow-cylindrical and arranged around the first cylindrical section 34 of the shaft 24. The sleeve 26 has a slot / elongated hole 44 in which the pin-shaped projection 36 provided on the shaft 24 is received or guided. The slot 44 defines a rotation range of the shaft 24 with respect to the sleeve 26. In particular, the slot 44 of the sleeve 26 allows approximately a 90° rotation of the shaft 24. The sleeve 26 has two pin-shaped projections 45, which are diametrically opposed to one another and extend radially outward. The pin-shaped projections 45 of the sleeve 26 are provided to be received in the V-shaped or U-shaped recesses 12 of the insertion instrument 6, so that the sleeve 26 is held in the insertion instrument 6 in a rotationally secure manner.

[0062] The spring 28 is a spiral spring or a compression spring and is arranged between a support surface 46 (for the spring 28) formed at a proximal end of the second cylindrical portion 38 of the shaft 24 and a contact surface 48 (for the spring 28) formed at a distal end of the sleeve 26.

[0063] The slotted guide 44 of the sleeve 26 extends obliquely, i.e. it extends both in the circumferential direction and in the axial direction of the sleeve 26. This means that a first end 50 of the slotted guide 44 is arranged closer to a distal end of the sleeve 26 than a second end 52 of the slotted guide 44. The slotted guide 44, which is particularly Fig. 7 or Fig. 8 The resulting shape of the link 44 can also be mirrored (design for left-handers).

[0064] The spring 28 applies a compressive force to the sleeve 26 and presses the sleeve 26 axially upward. As a result, the peg-shaped projection 36 of the shaft 24 is automatically or independently pressed against the first end 50 of the slotted guide 44. When the peg-shaped projection 36 of the shaft 24 is located at the first end 50 of the slotted guide / the elongated hole 44, this represents a defined starting position / zero position / original position. In this defined starting position, the sleeve 26 and the shaft 24 are arranged relative to one another such that, when the peg-like projections 45 of the sleeve 26 are received in the V-shaped recesses 12 of the insertion instrument 6 and held securely against rotation, the non-circular distal engagement section 43 of the shaft 24 is arranged with respect to the coupling arms 16 of the insertion instrument 6 such that the coupling arms 16 are not spread apart.In other words, the shaft / rod 24 and the sleeve 26 of the decoupling instrument 4 are automatically aligned with each other for insertion / introduction into the insertion instrument 6.

[0065] When the decoupling instrument 4 is inserted into the insertion instrument 6, the sleeve 26 (the peg-shaped projections 45 of the sleeve 26) is held securely against rotation in the V-shaped or U-shaped recesses 12 of the insertion instrument 6. A user / surgeon can now rotate the shaft 24 with respect to the sleeve 26 by approximately 90° by turning the proximal handle section 30 clockwise until the peg-shaped projection 36 of the shaft 24 is located at the second end 52 of the slotted guide / elongated hole 44. In this position, the oval-shaped distal engagement section 43 of the shaft 24 spreads the coupling arms 16 of the insertion instrument 6, thus decoupling the insertion instrument 6 from the pedicle screw.

[0066] As is particularly evident from Fig. 8 As can be seen, the slotted guide / elongated hole 44 can have a recess / notch / trough 54 at its second end 52. However, it is also conceivable that the recess 54 is not provided. When the peg-shaped projection 36 of the shaft 24 at the second end 52 of the slotted guide 44 slides or falls or is received into the recess 54, that is to say, in particular, is pressed into the recess 54 by the spring 28, a user / surgeon is given tactile feedback which indicates to the user / surgeon that the insertion instrument 6 is decoupled from the pedicle screw.

[0067] In this position, unintentional slipping out of the decoupling instrument 4 is prevented by the pressure piece 40, which presses against the insertion instrument 6 from the inside, the recess 54 on the link 44, and the contact between the decoupling instrument 4 and the insertion instrument 6 at their distal end.

[0068] To decouple the two instruments (decoupling instrument 4 and insertion instrument 6), the decoupling instrument 4 can be turned back 90° counterclockwise (assisted by the spring force) so that the sleeve 26 is again in the zero position / starting position for the next application. List of reference symbols

[0069] 2Medical-technical arrangement 4Decoupling instrument 6Insertion instrument 8Main body 10Upper receiving section 12V-shaped recess 14Inner threaded section 16Coupling arm 18Locking lug 20Locking sleeve 22Transition area 24Shaft / rod 26Sleeve 28Spring 30Proximal handle section 32Elongated recess 34First cylindrical section 36Peg-shaped projection (of the shaft / rod) 38Second cylindrical section 40Pressure piece 42Third cylindrical section 43Distal engagement section 44Link / elongated hole 45Peg-shaped projection (of the sleeve) 46Support surface 48Contact surface 50First end 52Second end 54Depression / notch / trough

Claims

1. A medical decoupling instrument (4) for decoupling a medical insertion instrument (6) from a pedicle screw, comprising: a shaft (24) and a sleeve (26) which is arranged around a portion (34) of the shaft (24), said sleeve (26) being configured for defined coupling to the medical insertion instrument (6), wherein the shaft (24) is rotatable with respect to the sleeve (26), and wherein the medical decoupling instrument (4) is configured to move the shaft (24) and the sleeve (26) self-actingly and automatically into a defined initial position; wherein the medical decoupling instrument (4) further comprises a spring (28) which is arranged between a support surface (46), which is provided on the shaft (24), and the sleeve (26) and is configured to move the shaft (24) and the sleeve (26) into the defined initial position via its spring force; wherein the shaft (24) has a peg-shaped projection (36) at the portion (34) around which the sleeve (26) is arranged, the sleeve (26) has a motion link (44), and the peg-shaped projection (36) of the shaft (24) is received in the motion link (44) of the sleeve (26) such that the motion link (44) defines a range of rotation of the shaft (24) with respect to the sleeve (26); characterized in that the motion link (44) runs obliquely, i.e. extends both in the circumferential direction and the axial direction of the sleeve (26), such that a first end (50) of the motion link (44) is arranged closer to a distal end of the sleeve (26) than a second end (52) of the motion link (44).

2. The medical decoupling instrument (4) according to claim 1, wherein, in the defined initial position, the peg-shaped projection (36) of the shaft (24) is pressed against the first end (50) of the motion link (44) by the spring (28).

3. The medical decoupling instrument (4) according to claim 1 or 2, wherein the motion link (44) has a depression (54) at its second end (52) such that the peg-shaped projection (36) of the shaft (24) can be pressed into the depression (54) via the spring (28).

4. The medical decoupling instrument (4) according to one of the preceding claims, wherein the sleeve (26) has peg-shaped projections (45) for defined coupling to5. The medical decoupling instrument (4) according to one of the preceding claims, wherein the shaft (24) has a distal engagement portion (43) that is cylindrically shaped with a non-circular cross-section.

6. The medical decoupling instrument (4) according to one of the preceding claims, wherein a portion (38) of the shaft (24) has a push piece or an engagement mechanism (40) that is configured to apply a push force radially outward.

7. A medical assembly (2) comprising at least the medical decoupling instrument (4) according to one of the preceding claims and a medical insertion instrument (6).