CN114983625A

CN114983625A - Adjustable nasolacrimal duct support and implanting device thereof

Info

Publication number: CN114983625A
Application number: CN202210590379.0A
Authority: CN
Inventors: 贾亮; 陶海; 白芳
Original assignee: Third Medical Center of PLA General Hospital
Current assignee: Third Medical Center of PLA General Hospital
Priority date: 2022-05-26
Filing date: 2022-05-26
Publication date: 2022-09-02
Anticipated expiration: 2042-05-26
Also published as: CN114983625B

Abstract

The invention discloses an adjustable nasolacrimal duct bracket and an implanting device thereof, comprising a nasolacrimal duct bracket and an implanting device; the nasolacrimal duct bracket is detachably connected with the implanting device; the nasolacrimal duct stent comprises a first stent and a second stent; the second bracket is arranged outside the first bracket; arranging an expansion structure used for changing the pipe diameter of a second stent between the first stent and the second stent; the expansion structure comprises a supporting structure and a locking structure; the supporting structure is connected with the locking structure; the imbedding device comprises a loader, an adjusting device and a pushing structure; the adjusting device is arranged inside the loader; the pushing structure is arranged inside the adjusting device.

Description

Adjustable nasolacrimal duct support and implanting device thereof

Technical Field

The invention belongs to the technical field of medical instruments, and particularly relates to an adjustable nasolacrimal duct stent and an implanting device thereof.

Background

The artificial nasolacrimal duct stent implantation is a new therapy for treating dacryocystitis by implanting an artificial nasolacrimal duct through an interventional therapy technology, and belongs to a minimally invasive therapy method. The technology is suitable for treating chronic dacryocystitis, nasolacrimal passage obstruction, nasolacrimal passage stenosis, and nasal cavity dacryocystitis reocclusion. The technique expands nasolacrimal duct from nasal cavity in a retrograde manner without operation and pain during operation. Hospitalization is not needed, and daily life and work are not affected. The nasolacrimal duct stent is made of a novel artificial heart valve material, so that rejection reaction is avoided, the nasolacrimal duct stent does not need to be taken out after operation, and the nasolacrimal duct stent can be kept for life, so that the curative effect is ensured. Has the following advantages:

1. the operation is simple, safe and time-saving, and the patient does not need to be in hospital;

2. the bleeding is less, the pain is less, and the patient can tolerate the pain;

3. the original anatomical position is not changed, and the artificial nasolacrimal duct can be inserted again or changed into other methods after being blocked;

4. no skin incision is made, and no scar is left on the surface of the skin;

5. has wide operation indication and definite curative effect.

However, the nasolacrimal duct stent used at present has a fixed caliber, which makes it difficult to implant and remove. Similarly, it is difficult to adapt to various patient needs.

The invention aims at the problems and provides an adjustable nasolacrimal duct bracket and an implanting device thereof.

Disclosure of Invention

In order to overcome the problems of the background art, the invention provides an adjustable nasolacrimal duct stent and an implanting device thereof.

An adjustable nasolacrimal duct bracket and an implanting device thereof, which comprises a nasolacrimal duct bracket and an implanting device; the nasolacrimal duct bracket is detachably connected with the implanting device; the nasolacrimal duct stent comprises a first stent and a second stent; the second bracket is arranged outside the first bracket; arranging an expansion structure used for changing the pipe diameter of a second stent between the first stent and the second stent; the expansion structure comprises a supporting structure and a locking structure; the supporting structure is connected with the locking structure; the imbedding device comprises a loader, an adjusting device and a pushing structure; the adjusting device is arranged inside the loader; the pushing structure is arranged inside the adjusting device.

Further, the supporting structure is arranged on the outer side wall of the first support and connected with the first support.

Further, the supporting structure is fixedly connected with the second support.

Further, the first bracket comprises an inner tube and a first fixing structure; the inner tube is integrally connected with the first fixing structure.

Further, the second bracket includes an external unit; the number of the external units is A, and A is more than 2.

Further, the external unit is slidably connected to an adjacent external unit.

Further, the supporting structure is rotatably connected with the locking structure.

Further, adjusting device is connected with the transport structure rotation.

Furthermore, a second limiting structure is arranged at one end of the pushing structure; the second limiting structure is connected with the pushing structure.

Furthermore, the second limiting structure is detachably connected with the locking structure.

The invention has the beneficial effects that: the nasolacrimal duct bracket is changed in a large range, the function of adjusting the pipe diameter is added, the implantation and the taking-out operation are carried out after the nasolacrimal duct bracket is reduced, and the operation is convenient and fast; meanwhile, the requirements of various patients can be met, the pipe diameter of the nasolacrimal duct support can be freely adjusted, and the firmness of the nasolacrimal duct support in the body of the patient is improved.

Drawings

FIG. 1 is a schematic structural view of the overall structure of the present invention;

FIG. 2 is a schematic structural view of the nasolacrimal duct stent of the present invention;

fig. 3 is a cross-sectional view of the nasolacrimal duct stent of the present invention;

FIG. 4 is a schematic view of a second stent in accordance with the present invention connected to an expanded configuration;

FIG. 5 is a schematic structural view of a first bracket according to the present invention;

FIG. 6 is a schematic structural view of a second bracket according to the present invention;

FIG. 7 is a schematic view of the structure of an external unit according to the present invention;

FIG. 8 is a top view of an external unit according to the present invention;

FIG. 9 is a cross-sectional view of an outer unit in the present invention;

FIG. 10 is a schematic view of a support structure according to the present invention;

FIG. 11 is a schematic structural view of a locking structure according to the present invention;

FIG. 12 is a cross-sectional view of a locking structure of the present invention;

FIG. 13 is a schematic illustration of the structure of a deployment device in accordance with certain embodiments of the present invention;

FIG. 14 is a schematic diagram of the structure of an adjustment device in some embodiments of the invention;

FIG. 15 is a schematic diagram of a push mechanism according to some embodiments of the present invention;

in the figure, 1, a first bracket; 11. an inner tube; 12. a first fixed structure; 13. a second fixed structure; 2. a second bracket; 21. an external unit; 211. a first sliding structure; 212. a second sliding structure; 213. a first limit structure; 3. an expanded configuration; 31. a support structure; 311. a first supporting unit; 312. a first positioning structure; 313. a second positioning structure; 32. a locking structure; 321. locking the sleeve; 322. a first adjustment structure; 323. a third positioning structure; 4. a loader; 5. an adjustment device; 51. adjusting the sleeve; 52. a second adjustment structure; 53. a first connecting structure; 6. a pushing structure; 61. a push rod; 62. a second limiting structure; 63. and a third adjustment structure.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below by specific embodiments, and it is obvious that the embodiments described are only a part of the embodiments of the present invention, rather than all embodiments, and other advantages and efficacies of the present invention can be easily understood by those skilled in the art from the disclosure of the present specification. The present invention can be implemented or applied by other different specific embodiments, and the features in the following embodiments and embodiments can be combined with each other without conflict, and all other embodiments obtained by a person of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.

An adjustable nasolacrimal duct stent and an insertion device thereof as shown in fig. 1-3, comprising a nasolacrimal duct stent and an insertion device; the nasolacrimal duct bracket is arranged in the imbedding device and is detachably connected with the imbedding device; the nasolacrimal duct stent is implanted into the lacrimal duct of a patient by using the implanting device, and can be taken out by using the implanting device when taken out.

The nasolacrimal duct bracket comprises a first bracket 1 and a second bracket 2; the second bracket 2 is arranged outside the first bracket 1; an expansion structure 3 for changing the pipe diameter of the second stent 2 is arranged between the first stent 1 and the second stent 2; the expansion structure 3 comprises a support structure 31 and a locking structure 32; the support structure 31 is connected to a locking structure 32. In some embodiments of the present application, the support structure 31 is rotatably connected with the locking structure 32.

The second rack 2 comprises external units 21, the number of external units 21 being A, A > 2. Preferably A > 10. The outer unit 21 is slidably connected to the adjacent outer unit 21.

One end of the first bracket 1 is provided with a first fixing structure 12, and the first fixing structure 12 is fixedly connected with the first bracket 1; the first fixing structure 12 is exposed to the outside of the second bracket 2. The outer side wall of the first fixing structure 12 is smooth and solid. If the outer side wall of the first fixing structure 12 is provided with a cavity, the newly-grown granulation tissue can easily grow into the cavity, and the difficulty in the taking-out process is increased. In some embodiments of the present application, the first fixation structure 12 is a spherical hollow shell; alternatively, the first fixing structure 12 is a square hollow shell

The imbedding device comprises a loader 4, an adjusting device 5 and a pushing structure 6, wherein the adjusting device 5 is arranged inside the loader 4; the pushing structure 6 is arranged inside the adjusting device 5, and the adjusting device 5 is rotatably connected with the pushing structure 6.

The nasolacrimal duct stent can be made of different materials and types of materials, such as completely degradable materials, partially degradable materials and completely non-degradable materials. The nasolacrimal duct bracket made of different materials is selected according to the state of illness of a patient so as to achieve the purpose of treating different types of diseases.

In some embodiments of the present application, a drug coating or drug coating is disposed on the exterior of the nasolacrimal duct stent to reduce local inflammatory reactions and reduce proliferation of granulation tissue.

The manner of connection of the second stent 2 to the expandable structure 3 as shown in fig. 4; the inner side wall of the second bracket 2 is fixedly connected with the outer side wall of the supporting structure 31. In some embodiments of the present application, the second stent 2 is heat-fused to the expansion structure 3. Alternatively, the second stent 2 is bonded to the stent 3 using glue.

A first bracket 1 as shown in fig. 5; it comprises an inner tube 11 and a first fixed structure 12; the inner tube 11 is integrally connected to a first fixed structure 12. In some embodiments of the present application, the first fixation structure 12 is made of an elastic material and is configured to be inserted into the patient's lacrimal passage. Alternatively, the first fixation structure 12 is a mushroom-like head structure. Alternatively, the first fixing structure 12 is a hollow triangular structure. Preferably, the inner tube 11 is a hollow tubular structure.

In some embodiments of the present application, the first bracket 1 further comprises a second fixing structure 13 for defining the relative position of the first bracket 1 and the support structure 31. The second fixing structure 13 is fixedly connected with the inner tube 11,

in other embodiments of the present application, the first bracket 1 further includes an external thread for connecting with the locking structure 32, the external thread is disposed at an end of the inner tube 11 far away from the first fixing structure 12, and the external thread is fixedly connected with the inner tube 11. To facilitate mounting of the support structure 31, the external thread is recessed, i.e. the maximum outer diameter of the external thread is smaller than or equal to the outer diameter of the inner tube 11.

An external unit 21 as shown in fig. 6-9; the external unit 21 is fixedly connected to the support structure 31; the locking structure 32 pushes the supporting structure 31 to move, the supporting structure 31 drives the external unit 21 to move along the radial direction of the second bracket 2, and the supporting structures 31 are connected in a sliding mode, so that the pipe diameter of the second bracket 2 is changed.

The external unit 21 includes a first sliding structure 211, a second sliding structure 212, and a first limiting structure 213; the first sliding structure 211 is arranged on a side wall of the second sliding structure 212, and the first sliding structure 211 is fixedly connected with the second sliding structure 212; the first sliding structure 211 and the second sliding structure 212 are not in the same plane, and an included angle between the first sliding structure 211 and the second sliding structure 212 is α, where α is (a-2) × 180 °/a. The first limiting structures 213 are respectively arranged at two ends of the second sliding structure 212, and the first limiting structures 213 are fixedly connected with the second sliding structure; the first sliding structure 211 and the second sliding structure 212 are both rectangular plate-shaped structures; the first limiting structure 213 is a "J" shaped plate structure, and the short side of the first limiting structure 213 is fixedly connected with the second sliding structure 212; a sliding groove is formed between the second limiting structure 62 and the first sliding structure 211, the sliding groove is matched with the first sliding structure 211, and the sliding groove is connected with the first sliding structure 211 on the adjacent external unit 21 in a sliding manner. Meanwhile, the first limiting structure 213 limits the sliding direction of the first sliding structure 211, so that the first sliding structure 211 can only slide inside the sliding slot. The plurality of external units 21 are connected with each other to form a hollow tubular structure having a polygonal cross section, and the length of the cross section side and the cross section area of the hollow tubular structure can be freely adjusted. That is, the first sliding structure 211 slides relative to the second sliding structure 212 of the adjacent external unit 21, and the external units 21 cooperate with each other to change the cross section of the second support 2 into a polygon with adjustable side length, so as to adjust the pipe diameter of the second support 2 by adjusting the side length of the cross section of the second support 2. The number of sides of the cross-sectional polygon of the second stent 2 is controlled by the number of external units 21, i.e., the number of sides of the cross-sectional polygon is also a. The larger the number of sides of the cross-sectional polygon, the closer to a circle.

The supporting structure 31 shown in fig. 10 includes a first supporting unit 311, a first positioning structure 312 and a second positioning structure 313; the first supporting unit 311 is made of an elastic material, and under the condition of no external force interference, the first supporting unit 311 is a strip-shaped plate structure with a large radian, the included angle of two ends of the first supporting unit is beta, and the beta is less than 160 degrees; deformation occurs under the interference of external force, and the external force can be restored to the original shape after disappearance. The first supporting unit 311 has one end fixedly connected to the first positioning structure 312, the other end fixedly connected to the second positioning structure 313, and the middle portion fixedly connected to the external unit 21. The first positioning structure 312 is connected to the second fixing structure 13, and the first positioning structure 312 is disposed on a side of the second fixing structure 13 away from the first fixing structure 12. The number of the first supporting units 311 is B, and B is a. In some embodiments of the present application, a middle portion of the first supporting unit 311 is fixedly connected with an inner sidewall of the first sliding structure 211. Optionally, the first supporting unit 311 is connected with the first sliding structure 211 in a hot-melting manner; or the first supporting unit 311 is adhered to the first sliding structure 211 by glue. In some embodiments of the present application, the first positioning structure 312 is thermally fused to the second fixing structure 13; or the first positioning structure 312 and the second fixing structure 13 are glued.

In some embodiments of the present application, a positioning ring is disposed on an end surface of the second positioning structure 313 away from the first supporting unit 311, and the positioning ring is used to fix a relative position between the second positioning structure 313 and the locking structure 32, so as to prevent the second positioning structure 313 from being separated from the locking structure 32 during use.

The second fixing structure 13 is fixedly connected with the inner tube 11, the first supporting unit 311 is fixedly connected with the outer unit 21, the first positioning structure 312 is connected with the second fixing structure 13, and the second positioning structure 313 is rotatably connected with the locking structure 32. The locking structure 32 and the second fixing structure 13 fix the support structure 31 from two opposite directions in a straight line. The distance between the locking structure 32 and the second fixing structure 13 is reduced, the first supporting unit 311 bends under the driving of its own elasticity, and pushes the second sliding structure 212 and the first sliding structure 211 of the adjacent external unit 21 to slide with each other, so that the second stent 2 is expanded; the distance between the locking structure 32 and the second fixing structure 13 is enlarged, the first supporting unit 311 is gradually extended under the driving of an external force, and the second sliding structure 212 and the first sliding structure 211 of the adjacent external unit 21 are pulled to slide with each other, so that the second bracket 2 is contracted.

The locking structure 32 shown in fig. 11-12, which includes a locking sleeve 321, a first adjustment structure 322 and a third positioning structure 323; the locking sleeve 321 is a circular tubular structure, the locking sleeve 321 is arranged outside the inner tube 11, the locking sleeve 321 is inserted into the inner tube 11, and the inner diameter of the locking sleeve 321 is larger than the outer diameter of the inner tube 11.

The first adjustment structure 322 is disposed on an outer sidewall of the locking sleeve 321, and the first adjustment structure 322 is integrally connected with the locking sleeve 321. The cross section of the first adjusting structure 322 is a hollow regular polygon, which is convenient for rotating the locking sleeve 321, and prevents the difficulty in rotating the locking sleeve 321 due to the fact that the outer wall of the locking sleeve 321 is too smooth, which leads to difficulty in operating the expansion structure 3.

The third positioning structure 323 is disposed on an end surface of the locking sleeve 321, the third positioning structure 323 is fixedly connected to the locking sleeve 321, and the third positioning structure 323 is rotatably connected to the second positioning structure 313. Preferably, a positioning cabin adapted to the positioning ring is disposed inside the third positioning structure 323, and the positioning cabin is slidably connected to the positioning ring.

In some embodiments of the present application, internal threads are provided on the inner sidewall of the locking sleeve 321 distal to the third positioning structure 323, which internal threads mate with external threads on the inner tube 11. The locking structure 32 is rotated to move the locking structure 32 along the inner tube 11 away from or close to the second fixing structure 13, so as to deform the supporting structure 31 and drive the second stent 2 to expand or contract.

The inserting device shown in fig. 13 comprises a loader 4, an adjusting device 5 and a pushing structure 6, wherein the adjusting device 5 is arranged inside the loader 4; the pushing structure 6 is arranged inside the adjusting device 5, and the adjusting device 5 is rotatably connected with the pushing structure 6. In some embodiments of the present application, the cartridge 4 is a circular tubular structure, the adjustment device 5 is a circular tubular structure, and the pushing structure 6 is a circular cylindrical structure; the inner diameter of the loader 4 is larger than the outer diameter of the adjusting device 5, and the inner diameter of the adjusting device 5 is larger than the outer diameter of the pushing structure 6.

The adjusting device 5 shown in fig. 14 comprises an adjusting sleeve 51 and a second adjusting structure 52, wherein the second adjusting structure 52 is arranged on an end face of the adjusting sleeve 51, and the adjusting sleeve 51 is fixedly connected with the second adjusting structure 52; preferably, the adjustment sleeve 51 is integrally connected to the second adjustment structure 52. The adjusting sleeve 51 is a circular tubular structure, and the second adjusting structure 52 is a circular tubular structure with a regular polygon inner wall. The second adjustment structure 52 is adapted to the first adjustment structure 322, and the movement of the locking structure 32 on the inner tube 11 is controlled by rotating the first adjustment structure 322 using the second adjustment structure 52.

In some embodiments of the present application, an end of the adjusting sleeve 51 away from the second adjusting structure 52 is provided with a first connecting structure 53 for connecting with the pushing structure 6; the first connecting structure 53 is fixedly connected with the adjusting sleeve 51; preferably, the first connecting structure 53 is integrally connected with the adjusting sleeve 51. The adjusting sleeve 51 is of a circular tubular structure, and the outer diameter of the adjusting sleeve 51 is equal to that of the adjusting sleeve 51; the inner diameter of the adjustment sleeve 51 is smaller than the inner diameter of the adjustment sleeve 51; the inner diameter of the adjustment sleeve 51 is larger than the outer diameter of the push structure 6.

The pushing structure 6 shown in fig. 15 comprises a pushing rod 61, a second limiting structure 62 and a third adjusting structure 63; the pushing rod 61 is of a circular tubular structure; the third adjusting structure 63 is disposed inside the push rod 61, and the third adjusting structure 63 is threadedly coupled to the push rod 61. The second limiting structure 62 is arranged at one end of the pushing rod 61 far away from the third adjusting structure 63, the second limiting structure 62 is located on the side wall of the pushing rod 61, and the second limiting structure 62 is fixedly connected with the pushing rod 61.

In some embodiments of the present application, the second limiting structure 62 is a cylindrical air bag, the cylindrical air bag is communicated with the inner channel of the second limiting structure 62, and a sealing structure is disposed on the connecting surface of the third adjusting structure 63 and the second limiting structure 62. Rotating the third adjusting structure 63 to enable the third adjusting structure 63 to extend into the pushing rod 61, and extruding air in the pushing rod 61 into the columnar air bag to enable the columnar air bag to expand; the third adjusting structure 63 is reversed to withdraw the third adjusting structure 63 from the pushing rod 61, and the air in the columnar air bag is squeezed into the pushing rod 61 to contract the columnar air bag.

The application method comprises the following steps:

1) dilating the punctum, and dilating the punctum by a punctum dilator;

2) probing the lacrimal passage by using an empty lacrimal passage probe through the lacrimal canaliculus and the lacrimal sac according to the conventional method;

3) inserting a guide wire, inserting the thin end of the guide wire into the inferior nasal passage through the hollow lacrimal probe, and taking out the guide wire from the anterior nostril to the inferior nasolacrimal passage by using a guide wire hook;

4) retrograde dilated nasolacrimal duct

4-1) firstly, a guide wire is penetrated from the tip of the dilator and the dilator is sent into the nasal cavity, then the guide wire is wound on the middle finger or the index finger of the left hand and the right hand, the guide wire is tensioned, and the left middle finger or the index finger is pressed on the lacrimal sac part to protect the lacrimal sac;

4-2) expanding the nasolacrimal duct from the inferior nasal passage in a reverse way along the guide wire by using the lacrimal duct expander until the expander crosses the blocked nasolacrimal duct to reach the lacrimal sac and senses whether the expander is expanded in place or not, and withdrawing the expander core rod after the expander core rod is confirmed to be in place;

5) bracket for sending into nasolacrimal duct

5-1) inserting the second limiting structure 62 into the inner tube 11, rotating the third adjusting structure 63 to enable the third adjusting structure 63 to extend into the pushing rod 61, and extruding air in the pushing rod 61 into the second limiting structure 62 to enable the second limiting structure 62 to expand and be firmly fixed in the inner tube 11;

5-2) connecting the second limit structure 62 with the locking structure 32, rotating the second limit structure 62, and driving the second bracket 2 to contract through the supporting structure 31;

5-3) inserting the nasolacrimal duct stent into the loader 4, keeping the first fixing structure 12 away from the adjusting device 5, simultaneously drawing the first fixing structure 12, and completely placing the nasolacrimal duct stent into the loader 4;

5-4) inserting a guide wire into one end of the loader 4 far away from the pushing structure 6, sending the nasolacrimal duct bracket into the lacrimal sac along the outer sleeve of the dilator, pressing the pusher after the nasolacrimal duct bracket is sent to the position, slowly withdrawing from the outer sleeve of the lacrimal passage dilator, and then rotating the adjusting device 5 to change the outer diameter of the second bracket 2 so as to adapt to the lacrimal passage of the patient;

5-5) reversing the third adjustment structure 63 to retract the second stop structure 62 and remove the pushing structure 6 and adjustment device 5 from the patient's lacrimal passage;

6) determining the position of the artificial nasolacrimal duct, observing whether the nasolacrimal duct is placed in place by using a nostril snooping device, and if the position is placed too high or too low, taking out the nasolacrimal duct bracket to place again until the placement is satisfied;

7) the guide wire is withdrawn.

The above description of the embodiments is only for the understanding of the present invention. It should be noted that modifications could be made to the invention without departing from the principle of the invention, which would also fall within the scope of the claims of the invention.

Claims

1. An adjustable nasolacrimal duct bracket and an implanting device thereof, which comprises a nasolacrimal duct bracket and an implanting device; it is characterized in that the nasolacrimal duct bracket is detachably connected with the imbedding device; the nasolacrimal duct stent comprises a first stent and a second stent; the second bracket is arranged outside the first bracket; arranging an expansion structure used for changing the pipe diameter of a second stent between the first stent and the second stent; the expansion structure comprises a supporting structure and a locking structure; the supporting structure is connected with the locking structure; the imbedding device comprises a loader, an adjusting device and a pushing structure; the adjusting device is arranged inside the loader; the pushing structure is arranged inside the adjusting device.

2. The adjustable nasolacrimal duct stent and insertion device thereof of claim 1, wherein the support structure is disposed on an outer sidewall of the first stent, and the support structure is connected to the first stent.

3. The adjustable nasolacrimal duct stent and the insertion device thereof of claim 2, wherein the support structure is fixedly connected to the second stent.

4. The adjustable nasolacrimal duct stent and the insertion device thereof of claim 2, wherein the first stent comprises an inner tube and a first fixation structure; the inner tube is integrally connected with the first fixing structure.

5. The adjustable nasolacrimal duct stent and the insertion device thereof of claim 3, wherein the second stent comprises an outer unit; the number of the external units is A, and A is more than 2.

6. The adjustable nasolacrimal duct stent and the insertion device thereof of claim 5, wherein the outer unit is slidably connected to an adjacent outer unit.

7. The adjustable nasolacrimal duct stent and the insertion device thereof of claim 1, wherein the support structure is rotatably connected with the locking structure.

8. An adjustable nasolacrimal duct stent and an insertion device thereof according to any one of claims 1-7, wherein the adjustment device is rotatably connected with the pushing structure.

9. The adjustable nasolacrimal duct stent and the insertion device thereof of claim 8, wherein one end of the pushing structure is provided with a second limiting structure; the second limiting structure is connected with the pushing structure.

10. The adjustable nasolacrimal duct stent and the insertion device thereof of claim 9, wherein the second limiting structure is detachably connected with the locking structure.