A microminiature surgical operating instrument

Abstract

The application relates to a microsurgical operating instrument, belonging to the field of medical instruments, which comprises a detachable outer rod assembly and a clamp head assembly, and an outer tube inner pull rod installed in the inner part of the outer rod assembly, the clamp head assembly comprises a clamp seat, a clamp seat inner pull rod and a clamp head, the clamp head is driven to open or close under the mechanical movement of the clamp seat inner pull rod, the outer rod assembly is detachably installed with the clamp seat, the outer tube inner pull rod is detachably installed with the clamp seat inner pull rod, and the outer rod assembly comprises a first outer tube and a reinforcing tube nested in the inner part of the first outer tube, the combination of the reinforcing tube and the outer tube realizes the rigidity and toughness of the micro rod instrument.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of medical devices, and particularly relates to a microminiature surgical operating device with a rod size of less than or equal to 3 mm. BACKGROUND

[0002] In traditional multi-pore endoscopic minimally invasive surgery, a plurality of puncture holes are inserted on the body surface, and a plurality of puncture devices are installed. Different instruments and endoscopes enter the body through different puncture devices to complete the surgery. In single-port laparoscopic surgery, for example, a single-port laparoscopic surgery is performed through the navel. Due to the chopstick effect and instrument fighting, the learning curve of single-port laparoscopic surgery is lengthened, so the prior art also proposes a "one plus one" surgical method, that is, in addition to the navel main incision for entering the related instruments, an additional puncture device incision is newly added. The newly added puncture device channel can enter some instruments to cooperate with the action in some special scenes during the operation to improve the operation efficiency. The prior art also proposes a more minimally invasive solution, that is, in addition to the existing single-port surgery navel main incision, a rod of an instrument with a size of not more than 2 mm is designed to be directly inserted into the human body, and then a 2-mm instrument rod is installed with a 5-mm forceps head to perform subsequent surgical operations. At this time, the incision caused by the 2-mm instrument rod is small, and no scar is left after the operation. However, the current 2-mm instrument has an inner pull rod inserted into the outer tube with a size of 1 mm, so the wall thickness of the 2-mm outer tube is in the range of 0.4-0.5 mm. The prior art solution usually adopts stainless steel materials such as 304 and 316, which are commonly used in the medical field to make medical instruments. The hardness of the material is 70-90 HRB, so the bending resistance is relatively low. When the instrument is used to pull and move related tissues with an angle during the operation, the instrument rod cannot support the normal use requirement due to the insufficient bending resistance. However, the thin-walled capillary tube will be brittle if the hardness is increased by heat treatment. At present, there is no mature solution for the 2-mm or so microminiature instrument to balance the rigidity and toughness, so the 3-mm instrument has been put into clinical use on the market, but there is still a risk of damage.

[0003] In addition, in the existing technical solutions, the detachable and combinable instruments have their working pliers with outer and inner threads that correspond to the outer and inner threads of the rod assembly. According to the thread design, the standard pitch of M2 thread is 0.4 mm (coarse thread) or 0.25 mm (fine thread), and the standard pitch of M1 thread is 0.25 mm (coarse thread) or 0.2 mm (fine thread). Taking an outer tube with an outer diameter of 2 mm and a wall thickness of 0.4~0.5 mm as an example, due to the thin wall thickness, a fine thread of 0.25 mm is usually adopted. The internal pull rod that drives the forceps head inside the outer tube has a diameter of 1 mm, and the M1 thread usually adopts a standard coarse external thread of 0.25 mm. It is usually a thread in the same direction, so it is a thread fit with the same pitch in the same direction. There is a problem with this solution. When the tissue volume or weight held by the forceps head is relatively large, the instrument head is blocked from rotating by the resistance of the tissue. If the drive wheel at the handle end rotates the instrument rod, it will be in the direction that loosens the threads of the instrument rod and the forceps head. This will cause the instrument head and the instrument rod to loosen or even fall off during the operation, resulting in functional failure and requiring reassembly.

[0004] Therefore, a better solution is urgently needed to address the two issues mentioned above: one is to balance rigidity and toughness, and the other is to prevent the instrument head from loosening during the rotation of the instrument rod during surgery. Summary of the Invention

[0005] To address the aforementioned problems, this invention discloses a miniature surgical instrument that features a separate design for the forceps head and the shaft. The forceps head is relatively large to meet usage requirements, while the shaft is smaller, resulting in a smaller puncture hole, less trauma, and faster postoperative recovery. Furthermore, an improved miniature surgical instrument is proposed to achieve a balance between rigidity and flexibility.

[0006] The specific technical solution is as follows: A miniature surgical instrument includes a detachable outer rod assembly and a forceps head assembly, as well as an inner pull rod installed through the outer tube inside the outer rod assembly. The forceps head assembly includes a forceps seat, an inner pull rod inside the forceps seat, and a forceps head. The forceps head is driven to open or close by the mechanical movement of the inner pull rod inside the forceps seat. The outer rod assembly is detachably installed with the forceps seat, and the inner pull rod inside the outer tube is detachably installed with the inner pull rod inside the forceps seat. The outer rod assembly includes a first outer tube and a reinforcing tube nested inside the first outer tube. A second outer tube and a third outer tube are respectively connected and installed at both ends of the first outer tube. The second outer tube and the third outer tube confine the reinforcing tube inside the first outer tube, axially limiting the reinforcing tube to ensure that it cannot be pulled out or rotated from the first outer tube. The hardness of the reinforcing tube is greater than that of the first outer tube. The inner pull rod inside the outer tube is a transmission rod that passes through the outer rod assembly; the inner pull rod inside the forceps seat is an internal pull rod that drives the opening and closing of the forceps head.

[0007] Furthermore, the hardness of the first outer tube is less than that of the reinforcing tube, with the hardness of the first outer tube being 70~90 HRB and the hardness of the reinforcing tube being 40~75 HRC.

[0008] Furthermore, the material of the first outer tube can be selected from 304 stainless steel, 316L stainless steel, etc., and the material of the reinforcing tube can be selected from titanium alloy, etc.

[0009] Furthermore, the second outer tube is detachably connected to the clamp seat.

[0010] Furthermore, the second outer tube includes an outer tube thread, the clamp seat includes a clamp seat thread, the second outer tube and the clamp seat are detachably connected through the threaded structure between the outer tube thread and the clamp seat thread, the distal end of the inner pull rod of the outer tube includes an inner pull rod thread, the inner pull rod of the clamp seat includes an inner pull rod thread, and the inner pull rod of the outer tube and the inner pull rod of the clamp seat are detachably installed through the threaded structure between the inner pull rod thread of the outer tube and the inner pull rod thread of the clamp seat.

[0011] Furthermore, the external tube thread and the internal tie rod thread of the clamp seat satisfy any of the following conditions: a) the thread directions are opposite, such as the external tube thread being left-handed and the internal tie rod thread being right-handed; b) the thread directions are the same but the pitches are not equal, such as the external tube thread pitch being M2×0.4 and the internal tie rod thread pitch being M1×0.3.

[0012] Furthermore, the two ends of the first outer tube are fixedly connected to the second and third outer tubes respectively by welding, bonding, or pin connection, or are detachably connected by threaded connection.

[0013] Furthermore, the diameter of the first outer tube is ≤3 mm.

[0014] Furthermore, the third outer tube includes a clamping block in the axial direction, and the proximal end of the inner pull rod of the outer tube includes an inner pull rod limiting surface. When the clamping block approaches and presses against the inner pull rod limiting surface, the inner pull rod of the outer tube does not rotate axially relative to the third outer tube and the first outer tube.

[0015] Furthermore, the region where the inner tie rod extends beyond the third outer tube includes a rotating boss, the diameter of which is larger than the diameter of the portion of the inner tie rod extending into the outer rod assembly.

[0016] A miniature surgical instrument assembly includes the aforementioned miniature surgical instrument and a handle assembly. The handle assembly includes a fixed handle side and a movable handle side. The proximal end of the third outer tube includes an outer tube groove. The fixed handle side includes an elastically retractable buckle. After the buckle is engaged with the outer tube groove, the outer rod assembly and the fixed handle side are fixedly connected. The proximal end of the inner pull rod of the outer tube includes a traction limiter. The movable handle side includes a handle groove. After the traction limiter is engaged with the handle groove, the inner pull rod of the outer tube and the movable handle side are fixedly connected.

[0017] A miniature surgical instrument kit includes a miniature surgical instrument as described above, and a cannula, wherein the inner hole of the cannula is in close sliding fit with the first outer tube, the cannula is a thin-walled capillary tube with a wall thickness ≤0.5 mm, the proximal end of the cannula includes a guide hole and a limiting large end, and the distal end includes a puncture tip.

[0018] The beneficial effects achievable through the above scheme include: by introducing a combination of inner and outer layers of materials with different hardness, the outer layer material is relatively soft, ensuring its toughness, while the inner layer material is harder and is contained and bound within the outer tough material. This not only improves the overall rigidity of the rod but also prevents the reinforcing tube of the inner hard material from bending and breaking, or even breaking off and falling into the body, thus providing a comprehensive protective effect. This scheme is particularly valuable in the field of micro-medical devices with an outer diameter of less than 3 mm.

[0019] Furthermore, the threaded connection between the instrument rod and the forceps head proposed in this invention adopts a design where the thread directions of the inner and outer connecting threads are opposite. This ensures that even when rotating the instrument head by turning the wheel at the handle end during surgery, the different thread directions create a mutual restraint that prevents the other from rotating. This avoids the risk of the instrument rod and head loosening and falling off due to rotating the instrument rod, as mentioned in the background art. Moreover, if the inner and outer threads are in the same direction but have different pitches, rotating the outer rod also achieves mutual restraint and prevents rotation of the two threads with different pitches. The threads can only be turned by independently rotating the inner and outer layers. However, due to the design of the clamping block and the inner pull rod limiting surface, the inner and outer layers cannot rotate independently when the clamping block and the inner pull rod limiting surface are pressed together. Therefore, the above-mentioned solution improves the safety and reliability of instrument use. Attached Figure Description

[0020] Figure 1 This is an assembly diagram of the rod portion of the ultra-miniature surgical instrument of this application;

[0021] Figure 2This is an exploded view of the rod portion of the miniature surgical instrument of this application;

[0022] Figure 3 This is a partial sectional view of the outer rod of the miniature surgical instrument of this application;

[0023] Figure 4 This is an overall center sectional view of the shaft portion of the miniature surgical instrument of this application;

[0024] Figure 5 A partial enlarged cross-sectional view (A) of the shaft portion of the miniature surgical instrument of this application;

[0025] Figure 6 This is a partial enlarged view of the cross-section of the rod portion of the miniature surgical instrument of this application (B section).

[0026] Figure 7 This is a partial enlarged cross-sectional view of the rod portion of the miniature surgical instrument of this application;

[0027] Figure 8 A schematic diagram of the miniature surgical instrument of this application with the handle attached;

[0028] Figure 9 Partial sectional view of the handle portion of the miniature surgical instrument of this application after the handle has been attached;

[0029] Figure 10 A schematic diagram of an instrument pack containing the microsurgical instruments of this application;

[0030] Figure 11 This is a center sectional view of the cannula inside the instrument package of this application;

[0031] Figure 12 This is a schematic diagram illustrating the clinical use of the device kit described in this application;

[0032] In the diagram: 1-Outer rod assembly; 2-Inner pull rod of outer tube; 3-Pliers head assembly; 4-Handle assembly; 5-Sleeve; 11-First outer tube; 12-Second outer tube; 13-Third outer tube; 14-Outer tube shoulder; 15-Locking cap; 16-Reinforcing tube; 17-Clamping block; 21-First inner pull rod; 22-Second inner pull rod; 31-Pliers seat; 32-Second pliers seat; 33-Inner pull rod of pliers seat; 34-Pliers head pin; 35-First pliers plate; 36-Second pliers plate; 37-Inner pull rod nut of pliers seat; 41-Handle fixed side; 42-Handle movable side; 4 3-Handle pivot; 44-Rotating wheel; 51-Limiting large end; 52-Guide hole; 53-Piercing tip; 54-Inner hole; 121-Outer tube thread; 122-Outer end face; 131-Inner end face; 141-First limiting surface; 151-Second limiting surface; 152-Locking cap internal thread; 211-Outer tube inner pull rod thread; 212-Pull rod tip; 221-Inner pull rod limiting surface; 222-Traction limiting; 223-Rotating boss; 311-Pliers seat internal thread; 371-Nut internal thread; 421-Handle slot; 441-Rotating wheel external thread. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings.

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] like Figure 1 , 2 As shown, a rod assembly of a miniature surgical instrument includes a detachable outer rod assembly 1 and a forceps assembly 3, and an inner pull rod 2 that penetrates and is installed inside the outer tube of the outer rod assembly 1. The outer rod assembly 1 includes a second outer tube 12, a first outer tube 11, and a third outer tube 13 connected in sequence. The second outer tube 12 includes an outer tube thread 121. The proximal end of the third outer tube 13 includes a protruding outer tube shoulder 14, which is located between the forceps assembly 3 and the second outer tube 12 and includes a locking cap 15 fitted on the outside of the third outer tube 13 and slidable axially along the outer wall of the third outer tube 13. Further reference... Figure 2As shown, the inner pull rod 2 of the outer tube includes a first inner pull rod 21 and a second inner pull rod 22. The distal end of the inner pull rod 2, i.e., the distal end of the first inner pull rod 21, includes an inner pull rod thread 211 and a pull rod tip 212 that can pierce skin tissue. The pull rod tip 212, due to its sharp end, can directly puncture the chest and abdominal wall. The proximal end of the inner pull rod 2, i.e., the proximal end of the second inner pull rod 22, includes an inner pull rod limiting surface 221 and a traction limiting surface 222. The inner pull rod 2 has a rotating boss 223. The diameter of the rotating boss 223 is larger than the diameter of the portion of the inner pull rod 2 that extends into the outer rod assembly 1, i.e., larger than the diameter of the second inner pull rod 22. The surface of the rotating boss 223 includes knurled threads, which facilitates hand-gripping and rotation of the inner pull rod 2, thus saving effort.

[0036] like Figure 3 The diagram shows a centerline cross-sectional view of the outer rod assembly, with enlarged schematic diagrams of the areas of the first outer tube 11, the second outer tube 12, and the third outer tube 13. Referring to the diagram, the first outer tube 11 is connected to the second outer tube 12 at its distal end and to the third outer tube 13 at its proximal end. A reinforcing tube 16 is installed inside the first outer tube 11. The outer end face 122 of the second outer tube 12 and the inner end face 131 of the third outer tube 13 confine the reinforcing tube 16 within the first outer tube 11, axially limiting its movement and ensuring it cannot be pulled out or rotated from the first outer tube. In a more preferred embodiment, the outer wall of the reinforcing tube 16 and the inner wall of the first outer tube 11 have a small gap fit, meaning they are in contact but do not affect their mutual axial sliding. The hardness of the first outer tube 11 is less than that of the reinforcing tube 16; the hardness of the first outer tube 11 is 70~90 HRB, and the hardness of the reinforcing tube 16 is 40~75 HRC. The first outer tube 11 is made of stainless steel 304 or 316L, and the reinforcing tube 16 is made of hard alloy, including titanium alloy. The first outer tube 11 is connected to the second outer tube 12 and the third outer tube 13 at both ends by a fixed connection, including welding, bonding, or pin connection, or a detachable connection, including threaded connection. The second outer tube 12 includes an outer tube thread 121. Further, the diameter of the first outer tube 11 is ≤3 mm.

[0037] By introducing the above-mentioned combination of inner and outer layers of materials with different hardness, the outer layer material is relatively soft, ensuring its toughness, while the inner layer material is harder and is contained and bound within the outer tough material. This not only improves the overall rigidity of the rod but also prevents the reinforcing tube of the inner hard material from bending and breaking, or even breaking off and falling into the body, thus providing a comprehensive protective effect. This solution is particularly valuable in the field of micro-medical devices with an outer diameter of less than 3 mm.

[0038] Figure 4, 5 Tables 6 and 7 show sectional views and enlarged partial views of multiple areas after the clamp head assembly has been installed. Further, as... Figure 5 As shown, the pliers assembly 3 includes a pliers base 31, a second pliers base 32, an inner pull rod 33 within the pliers base, and a pliers head pin 34. A pliers head, including a first pliers 35 and a second pliers 36, is mounted around the pliers head pin 34 as a pivot. The first pliers 35 and the second pliers 36 are driven to rotate around the pliers head pin 34 by the mechanical movement of the inner pull rod 33, thereby opening or closing the pliers head. An inner pull rod nut 37 with an inner hole is fitted to the end of the inner pull rod 33. The inner pull rod nut 37 includes an internal thread 371. The pliers base 31 includes an internal thread 311. The outer tube thread 121 of the second outer tube 12 is connected to the inner thread 311 of the clamp seat, and the outer tube inner thread 211 of the first inner pull rod 21 is connected to the inner thread 371 of the nut of the inner pull rod nut 37 of the clamp seat. Thus, the outer rod assembly 1 and the clamp seat 31 can be detachably installed, and the outer tube inner pull rod 2 and the clamp seat inner pull rod 33 can be detachably installed.

[0039] Figure 6 The diagram further details the fit between the first outer tube 11 and the third outer tube 13, as well as the schematic diagram showing the first inner tie rod 21 passing through the third outer tube 13 and the first outer tube 11.

[0040] like Figure 7 As shown, the outer tube shoulder 14 includes a first limiting surface 141, and the locking cap 15 includes a second limiting surface 151 and a locking cap internal thread 152. The locking cap 15 (sleeved on the outside of the proximal end of the third outer tube 13 and abutting against the outer tube shoulder 14) is axially fixed through the second limiting surface 151. The second inner pull rod 22 includes a traction limiting 222, a rotating boss 223, and an inner pull rod limiting surface 221 in sequence from the proximal end to the distal end. The third outer tube 13 includes a clamping block 17, which is fixedly connected to the third outer tube 13. Under the action of an external force in the axial direction, the clamping block 17 presses against the inner pull rod limiting surface 221 to prevent the second inner pull rod 22 from rotating relative to the third outer tube 13 along the axis, thereby realizing the synchronous rotation of the outer rod assembly 1 and the outer tube inner pull rod 2, and the rotational joint of the two is limited.

[0041] Based on this, the outer tube thread 121 of the second outer tube 12 and the inner tube thread 211 of the first inner pull rod 21 have opposite thread directions. For example, the outer tube thread is left-handed and the inner pull rod thread of the clamp seat is right-handed. This ensures that even when rotating the instrument head by turning the wheel at the end of the handle during the operation, the different thread directions inside and outside create a mutual resistance that prevents the other from rotating. This avoids the risk of the instrument rod and the head loosening their threads and falling off due to the rotating instrument rod mentioned in the background art.

[0042] Furthermore, if the outer tube thread 121 of the second outer tube 12 and the inner tube thread 211 of the first inner pull rod 21 are in the same direction, but their pitches are different (e.g., the outer tube thread pitch is M2×0.4, and the inner pull rod thread pitch is M1×0.3), then when rotating the outer rod, the two threads with different pitches can restrain each other and prevent rotation. The threads can only be turned by independently rotating the inner and outer layers. Therefore, this solution improves the safety and reliability of the instrument.

[0043] like Figure 8 , 9 As shown, a miniature surgical instrument includes the aforementioned miniature surgical instrument and a handle assembly 4. The handle assembly 4 includes a fixed handle side 41, a movable handle side 42, a handle shaft 43, and a rotating wheel 44. The movable handle side 42 can rotate along the handle shaft 43. The proximal end of the inner pull rod 2 of the outer tube includes a traction limit 222. The movable handle side 42 includes a handle slot 421. After the traction limit 222 is engaged with the handle slot 421, the inner pull rod 2 of the outer tube and the movable handle side 42 are fixedly connected. The rotating wheel 44 includes an external thread 441. The sliding locking cap 15 contacts and engages with the rotating wheel 44. The handle assembly is fixedly connected to the third outer tube 13 through the threaded engagement of the internal thread 152 of the locking cap and the external thread 441 of the rotating wheel 44. Rotating the movable handle side 42 pulls the inner pull rod 2 of the outer tube in an axial direction, thereby driving the forceps head to open and close.

[0044] like Figure 10 , 11 The illustrated miniature surgical instrument kit includes a miniature surgical instrument as described above, and a cannula 5. The inner hole 54 of the cannula 5 is tightly slidably fitted with the first outer tube 11. The cannula 5 is a thin-walled capillary tube with a wall thickness ≤0.5 mm. The proximal end of the cannula 5 includes a guide hole 52 and a limiting large end 51, and the distal end includes a puncture tip 53. Figure 10 The dashed line in the middle is the packaging sealing line.

[0045] likeFigure 12 As shown, after introducing the cannula 5, it can be percutaneously inserted into the abdominal wall first. Then, the first outer tube 11 enters the cannula 5 and slides axially along it. Because human skin tissue has a certain elasticity and adhesiveness, directly inserting or pulling the first outer tube 11 along the abdominal wall during surgery would be quite difficult, affecting the continuity of the surgery and increasing resistance. Therefore, introducing the cannula 5 makes the surgery smoother. However, limiting the wall thickness of the cannula, i.e., maximizing the limitation of the outer diameter of the cannula 5, reduces trauma to the abdominal wall.

[0046] In the figures of this invention, the same or similar reference numerals correspond to the same or similar components. In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the figure, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the figures are only for illustrative purposes and should not be construed as limiting this invention. For those skilled in the art, the specific meaning of the above-mentioned terms can be understood according to the specific circumstances.

[0047] It should be noted that when a component is referred to as being "connected" to another component, it can be directly connected to the other component or there may be an intermediate component; when a component is referred to as being "fixed" to another component, it can be directly fixed to the other component or there may be an intermediate component, which can be done by effective means such as bonding, welding, riveting, bolting, etc., which will not be listed in this application; when a component is referred to as being "movable" to another component, it can be done by rotation or sliding.

[0048] This application is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A miniature surgical instrument, characterized in that: The device includes a detachable outer rod assembly and a clamp head assembly, as well as an inner pull rod installed through the outer tube inside the outer rod assembly. The clamp head assembly includes a clamp seat, an inner pull rod inside the clamp seat, and a clamp head. The clamp head is driven to open or close by the mechanical movement of the inner pull rod inside the clamp seat. The outer rod assembly and the clamp seat are detachably installed, and the inner pull rod inside the outer tube and the inner pull rod inside the clamp seat are detachably installed. The outer rod assembly includes a first outer tube and a reinforcing tube nested inside the first outer tube. A second outer tube and a third outer tube are respectively connected and installed at both ends of the first outer tube. The second outer tube and the third outer tube confine the reinforcing tube inside the first outer tube, axially limiting the reinforcing tube to ensure that it cannot be pulled out or rotated from the first outer tube. The hardness of the reinforcing tube is greater than that of the first outer tube. This not only improves the overall rigidity of the rod but also prevents the inner hard material reinforcing tube from bending, breaking, or falling into the body, thus providing a comprehensive protective effect.

2. The miniature surgical instrument according to claim 1, characterized in that: The first outer tube material has a hardness of 70~90 HRB, and the reinforcing tube material has a hardness of 40~75 HRC.

3. The miniature surgical instrument according to claim 1, characterized in that: The second outer tube is detachably connected to the clamp seat.

4. The miniature surgical instrument according to claim 3, characterized in that: The second outer tube is detachably connected to the clamp seat. The second outer tube includes an outer tube thread, and the clamp seat includes a clamp seat thread. The second outer tube and the clamp seat are detachably connected through the threaded structure between the outer tube thread and the clamp seat thread. The distal end of the inner pull rod of the outer tube includes an inner pull rod thread, and the inner pull rod of the clamp seat includes an inner pull rod thread. The inner pull rod of the outer tube and the inner pull rod of the clamp seat are detachably installed through the threaded structure between the inner pull rod thread of the outer tube and the inner pull rod thread of the clamp seat.

5. The miniature surgical instrument according to claim 4, characterized in that: The external tube thread and the internal tie rod thread of the clamp seat meet any of the following conditions: a) the thread directions are opposite; b) the thread directions are the same but the pitches are not equal; the thread design with different internal and external directions or the thread design with the same internal and external directions but different pitches always has a mutual restraint between the internal and external to prevent the other from rotating, so as to avoid the instrument rod and the head from loosening their threads and falling off when rotating the instrument rod.

6. The miniature surgical instrument according to claim 1, characterized in that: The first outer tube is fixedly connected to the second and third outer tubes at both ends, including by welding, bonding, or pin connection, or is detachably connected including by threaded connection.

7. The miniature surgical instrument according to claim 1, characterized in that: The diameter of the first outer tube is ≤3 mm.

8. The miniature surgical instrument according to claim 1, characterized in that: The third outer tube includes a clamping block in the axial direction, and the proximal end of the inner pull rod of the outer tube includes an inner pull rod limiting surface. When the clamping block approaches and presses against the inner pull rod limiting surface, the inner pull rod of the outer tube does not rotate axially relative to the third outer tube and the first outer tube.

9. A miniature surgical instrument assembly, characterized in that: The invention includes a miniature surgical instrument as described in any one of claims 1-8, and a handle assembly. The handle assembly includes a fixed handle side and a movable handle side. The proximal end of the third outer tube includes an outer tube groove. The fixed handle side includes an elastically retractable buckle. After the buckle is engaged with the outer tube groove, the outer rod assembly and the fixed handle side are fixedly connected. The proximal end of the inner pull rod of the outer tube includes a traction limiter. The movable handle side includes a handle groove. After the traction limiter is engaged with the handle groove, the inner pull rod of the outer tube and the movable handle side are fixedly connected.

10. A miniature surgical instrument kit, characterized in that: The assembly includes a miniature surgical instrument as described in claim 9, and a cannula, wherein the inner bore of the cannula is in close sliding fit with the first outer tube, and the cannula is a thin-walled capillary tube with a wall thickness ≤0.5 mm.

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