Retrievable expandable intervertebral fusion cage assembly

Abstract

The present application relates to intervertebral fusion holder and catcher medical instrument technical field, specifically a kind of holder and catcher expandable intervertebral fusion instrument assembly, including intervertebral fusion and catcher, intervertebral fusion includes inner support block and outer expansion block, the outer expansion block includes four strip blocks, four strip blocks are divided into left lower strip block, left upper strip block, right upper strip block, right lower strip block, the cross section of four strip blocks is L type, four L type strip blocks are mutually buckled and arranged to form the outer expansion block whole with support cavity, left lower strip block and left upper strip block, left lower strip block and left upper strip block between are equipped with left and right connecting rod, left upper strip block and right upper strip block between, left lower strip block and right lower strip block between are equipped with upper and lower connecting rod, support cavity is inserted into inner support block by catcher, inner support block is equipped with the clamping hole of cooperation connection with catcher, with simple structure, stable after distraction, high strength after distraction, easy to implant and other advantages.

Description

Technical Field

[0001] This invention relates to the field of medical device technology for holding and retrieving interbody fusion devices, specifically a simple, stable, and high-strength retrieving expandable interbody fusion device assembly that is easy to implant. Background Technology

[0002] As is well known, spinal degenerative changes are common in orthopedic clinics, including intervertebral disc degeneration, spinal stenosis, spondylolisthesis, and compression of the spinal cord or nerve roots. Surgical treatment is often necessary to completely relieve the compression, restore the physiological curvature of the spine, and ensure spinal stability. Other patients with spinal deformities, trauma, tumors, those undergoing revision surgery, and those with infections may also require interbody fusion to stabilize the lumbar segments. Interbody fusion devices are effective for these spinal diseases, are simple to operate, convenient to use, have a high fusion rate, and do not have the complications associated with bone grafting fusion. They are now widely used in clinical practice.

[0003] In actual use, due to the excessive pressure on the fusion device in the vertical direction, and the fact that the left and right connecting rods on both sides of the fusion device are in a vertical state, the stress on the left and right connecting rods and the connecting posts on the fusion device will increase during the pressure process, eventually leading to the failure of the connecting posts and the left and right connecting rods, and thus the failure of the entire fusion device. At the same time, the existing interbody fusion devices are used in conjunction with the holding device, which has problems with low stability and poor holding effect during the opening process. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a simple, stable, strong, and easy-to-implant removable interbody fusion device assembly.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] An assembly for holding and expanding an interbody fusion device includes an interbody fusion device and a holder. The interbody fusion device comprises an inner support block and an outer expansion block. The outer expansion block includes four strip-shaped blocks: a lower left strip block, an upper left strip block, an upper right strip block, and a lower right strip block. The four strip blocks have L-shaped cross-sections and are interlocked to form an outer expansion block assembly with a supporting cavity. After interlocking, the outer expansion block has external meshing teeth on its upper and lower sides. Left and right connecting rods are provided between the lower left and upper left strip blocks, and between the lower left and upper left strip blocks. The upper and lower ends of the left and right connecting rods are respectively connected to the lower left and upper left strip blocks. The upper left strip block is hinged to the upper right strip block. Upper and lower connecting rods are provided between the upper left and upper right strip blocks and between the lower left and lower right strip blocks. The left and right ends of the upper and lower connecting rods are respectively hinged to the upper left and upper right strip blocks and the lower left and lower right strip blocks. An inner support block is inserted into the support cavity through a holder. The inner support block opens the four strip blocks after they are limited and rotated by the upper and lower connecting rods and the left and right connecting rods. The front end of the inner support block has an arc-shaped guide head. The inner support block has a snap-fit ​​hole that connects with the holder. The middle part of the left and right connecting rods is set as an elastic arc plate that bends outward. The left and right sides of the inner support block have protruding support ribs that support the upper and lower strip blocks.

[0007] The inner support block of the present invention is provided with internal meshing teeth at both ends. The inner wall of the L-shaped strip block is provided with fusion anti-detachment teeth that cooperate with the internal meshing teeth. In the fusion anti-detachment teeth, the single tooth of the internal meshing teeth is inclined to the rear side, and the single tooth of the fusion anti-detachment teeth is inclined to the front side. The internal meshing teeth and the fusion anti-detachment teeth are meshed and fixed together.

[0008] The left and right connecting rods of the present invention are provided with left and right clearance grooves on the strip blocks corresponding to the upper and lower ends of the strip blocks, and connecting posts are provided in the left and right clearance grooves. Connecting rings are provided at the upper and lower ends of the left and right connecting rods respectively. The upper and lower ends of the left and right connecting rods are connected to the connecting posts through the connecting rings to achieve the hinge connection between the left and right connecting rods and the strip blocks.

[0009] The upper and lower connecting rods of the present invention are provided with upper and lower clearance grooves on the strip blocks corresponding to the left and right ends, and connecting posts are provided in the upper and lower clearance grooves. Connecting rings are provided at the upper and lower ends of the upper and lower connecting rods respectively. The upper and lower connecting rods are hinged to the strip blocks by inserting the connecting rings into the connecting posts at the left and right ends of the upper and lower connecting rods.

[0010] The front end of one of the strip blocks (lower left, upper left, upper right, and lower right) described in this invention is provided with a baffle. The baffle is perpendicularly connected to the strip block, and the baffle is provided with a connecting screw hole for connecting a gripper.

[0011] The inner support block of the present invention has an inner locking single tooth on each of its left and right rear ends. The inner wall of the L-shaped strip block is provided with a lateral anti-detachment tooth group that cooperates with the inner locking single tooth. When the inner support block moves forward, the inner locking single tooth is inserted into the lateral anti-detachment tooth group in sequence to achieve anti-detachment locking.

[0012] The holder of the present invention includes a screw, an inner sleeve, an outer sleeve, a knob, and a locking block. The front end of the outer sleeve is provided with a snap-fit ​​connector that engages with the inner support block in the fusion device. The inner sleeve is located inside the outer sleeve and is slidably connected to the outer sleeve without rotation. The rear end of the inner sleeve extends out of the outer sleeve and is threadedly connected to the knob. The rear end face of the inner sleeve is provided with a fixing tooth. The screw is inserted into the inner sleeve, the front end of the screw extends out of the outer sleeve, and the rear end of the screw extends out of the inner sleeve and is provided with a locking block. The front end face of the locking block is provided with a locking tooth that engages with the fixing tooth. The screw, inner sleeve, and outer sleeve are locked without rotation by the engagement of the locking tooth and the fixing tooth.

[0013] The screw of the present invention has at least two ball grooves along the screw axis at its rear end. The locking block has a ball mounting hole, and a ball, a spring and a sealing cover are provided in the ball mounting hole. The ball is connected to the sealing cover by the spring and the sealing cover is fixed on the ball mounting hole.

[0014] The screw of the present invention is provided with a guide profile, and the locking block is provided with a guide groove surface that cooperates with the guide profile. The screw can slide without rotating within the locking block through the cooperation of the guide profile and the guide groove surface.

[0015] The screw of the present invention has an interface at its rear end that is connected and mated with a quick-change handle, and the screw is connected to the quick-change handle through the interface.

[0016] The snap-fit ​​connector at the front end of the outer tube of the present invention includes at least two snap-fit ​​springs. The snap-fit ​​springs are distributed in the circumferential direction of the end of the outer tube. The rear end of the snap-fit ​​springs is connected to the outer tube. The outer side of the front end of the snap-fit ​​springs is provided with a protruding snap-fit ​​head. The snap-fit ​​of the inner support block is realized by the cooperation between the snap-fit ​​head and the snap-fit ​​springs.

[0017] The present invention, due to the above-mentioned structure, has the advantages of simple structure, stability after expansion, high strength after expansion, and easy implantation. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the combined structure of the external expansion block of the present invention, wherein 1-1 is the front view after combination, and 1-2 is the top view after combination. Figure 1-3 This is the right view after the combination.

[0019] Figure 2This is a schematic diagram of the internal support block of the present invention, wherein 2-1 is a perspective view, 2-2 is a front view, 2-3 is a top view, and 2-4 is a right view.

[0020] Figure 3 This is a schematic diagram of the structure of the intervertebral fusion device of the present invention when it is spread out, wherein 3-1 is the front view, 3-2 is the top view, and 3-3 is the right view.

[0021] Figure 4 yes Figure 3 The diagram shows the structure of the left and right connecting rods, where 4-1 is the front view and 4-2 is the top view.

[0022] Figure 5 This is a schematic diagram of the structure of the outer extension block of the present invention, wherein 5-1 is a schematic diagram of the lower left strip block, 5-2 is a schematic diagram of the upper left strip block, 5-3 is a schematic diagram of the upper right strip block, and 5-4 is a schematic diagram of the lower right strip block.

[0023] Figure 6 This is a schematic diagram of the structure of the holder for holding the interbody fusion device in this invention.

[0024] Figure 7 yes Figure 6 A schematic diagram of the inner sleeve.

[0025] Figure 8 yes Figure 6 A schematic diagram of the locking block.

[0026] Figure 9 yes Figure 6 A schematic diagram of the middle screw.

[0027] Figure 10 yes Figure 6 A schematic diagram of the structure of the inner and outer jacket. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings:

[0029] As shown in the attached figure, a device assembly for holding and expanding an interbody fusion device includes an interbody fusion device and a holder. The interbody fusion device comprises an inner support block 8 and an outer expansion block 30. The outer expansion block 30 includes four strip-shaped blocks: a lower left strip block 1, an upper left strip block 2, an upper right strip block 3, and a lower right strip block 4. The cross-section of each strip block is L-shaped. The four L-shaped strip blocks are interlocked to form an outer expansion block 30 with a supporting cavity. After interlocking, the outer expansion block 30 has external meshing teeth 5 on its upper and lower sides. Left and right connecting rods 6 are provided between the lower left strip block 1 and the upper left strip block 2, and between the lower left strip block 1 and the upper left strip block 2. The upper and lower ends of the left and right connecting rods 6 are respectively connected to the lower left strip block 1 and the upper left strip block 2, and the lower right strip block 3. Strip block 1 and upper left strip block 2 are hinged together. Upper and lower connecting rods 7 are provided between upper left strip block 2 and upper right strip block 3, and between lower left strip block 1 and lower right strip block 4. The left and right ends of the upper and lower connecting rods 7 are respectively hinged to upper left strip block 2 and upper right strip block 3, lower left strip block 1 and lower right strip block 4. An inner support block 8 is inserted into the support cavity through a holder. The inner support block 8 opens the four strip blocks after they are limited and rotated by the upper and lower connecting rods 7 and the left and right connecting rods 6. The front end of the inner support block 8 has an arc-shaped guide head. The inner support block 8 has a snap-fit ​​hole that connects with the holder. The middle part of the left and right connecting rods 6 is set as an elastic arc plate that bends outward. The left and right sides of the inner support block 8 have protruding support ribs 9 that support the upper and lower strip blocks.

[0030] Because the left and right connecting rods are designed as elastic arc plates, when the outer expansion block receives pressure from the vertical direction, the inner support block deforms. The pressure is released onto the elastic arc plate through its elastic expansion, thus preventing deformation of the connecting column connected to the elastic arc plate. Furthermore, the pressure from the upper and lower surfaces falls between the upper and lower end faces of the outer expansion block and the inner support block, increasing the stress area and reducing the possibility of deformation of the inner support block. Therefore, the strength and stability of the entire structure can be maintained. Moreover, because the inner support block is equipped with support ribs, which support the outer sides of the strip blocks on the upper and lower sides, the support area is increased, resulting in greater overall structural strength and higher stability of the fusion device.

[0031] Furthermore, the inner support block is provided with internal meshing teeth 31 at both ends, and the inner wall of the L-shaped strip block is provided with fusion anti-detachment teeth 32 that cooperate with the internal meshing teeth 31. The fusion anti-detachment teeth 32 have one tooth of the internal meshing teeth 31 tilted to the rear side and one tooth of the fusion anti-detachment teeth 32 tilted to the front side. The internal meshing teeth 31 and the fusion anti-detachment teeth 32 are meshed together and fixed as a whole.

[0032] As mentioned above, the inner meshing teeth 31 on the upper and lower sides of the inner support block mesh with the fusion anti-detachment teeth 32 on the strip block, thus integrating the inner support block with the expanded outer extension block. This can prevent the inner support block from detaching and further increase the stability of the support between the inner support block and the outer extension block.

[0033] Furthermore, the upper and lower ends of the left and right connecting rods 6 are respectively provided with left and right clearance grooves 11 on the corresponding strip blocks, and a connecting post is provided in the left and right clearance grooves 11. The upper and lower ends of the left and right connecting rods 6 are respectively provided with connecting rings 13. The upper and lower ends of the left and right connecting rods 6 are connected to the connecting post by inserting the connecting rings 13 into the connecting post to realize the hinge connection between the left and right connecting rods 6 and the strip blocks.

[0034] Furthermore, the upper and lower connecting rods 7 are provided with upper and lower clearance grooves 12 on the strip blocks corresponding to the left and right ends, and connecting posts are provided in the upper and lower clearance grooves 12. The upper and lower ends of the upper and lower connecting rods 7 are provided with connecting rings 13. The upper and lower connecting rods 7 are hinged to the strip blocks by inserting the connecting rings 13 into the connecting posts.

[0035] Furthermore, a baffle 14 is provided at the front end of one of the strip blocks 1 (lower left), 2 (upper left), 3 (upper right), and 4 (lower right). The baffle 14 is perpendicularly connected to the strip block, and a connecting screw hole is provided on the baffle 14 for connecting the gripper.

[0036] Furthermore, the rear ends of the left and right sides of the inner support block are respectively provided with inner locking single teeth 33, and the inner wall of the L-shaped strip block is provided with a lateral anti-detachment tooth group 34 that cooperates with the inner locking single teeth 33. When the inner support block moves forward, the inner locking single teeth 33 are inserted into the lateral anti-detachment tooth group 34 in sequence to achieve anti-detachment locking. The inner locking single teeth 33 of the inner support block and the lateral anti-detachment tooth group 34 mesh with each other, further playing the role of preventing detachment.

[0037] Furthermore, the holder includes a screw 15, an inner sleeve 16, an outer sleeve 17, a knob 18, and a locking block 19. The front end of the outer sleeve 17 is provided with a snap-fit ​​connector that engages with the inner support block 8 in the fusion device. The inner sleeve 16 is located inside the outer sleeve 17. The inner sleeve 16 is slidably connected to the outer sleeve ring without rotation. The rear end of the inner sleeve 16 extends out of the outer sleeve 17 and is threadedly connected to the knob 18. The rear end face of the inner sleeve 16 is provided with a fixing tooth 20. The screw 15 is inserted into the inner sleeve 16. The front end of the screw 15 extends out of the outer sleeve 17. The rear end of the screw 15 extends out of the inner sleeve 16 and is provided with a locking block 19. The front end face of the locking block 19 is provided with a locking tooth 21 that engages with the fixing tooth 20. The screw 15, the inner sleeve 16, and the outer sleeve 17 are locked without rotation by the engagement of the locking tooth 21 with the fixing tooth 20.

[0038] Furthermore, the rear end of the screw 15 is provided with at least two ball grooves 22 along the axis of the screw 15, and the locking block 19 is provided with a ball mounting hole 23. The ball mounting hole 23 is provided with a ball, a spring and a sealing cover. The ball is connected to the sealing cover by the spring and the sealing cover is fixed on the ball mounting hole 23.

[0039] Furthermore, the screw 15 is provided with a guide profile 24, and the locking block 19 is provided with a guide groove surface 25 that cooperates with the guide profile 24. The screw 15 is connected to the locking block 19 by sliding without rotating through the cooperation of the guide profile 24 and the guide groove surface 25.

[0040] Furthermore, the rear end of the screw 15 is provided with an interface 26 that connects and cooperates with the quick-change handle, and the screw 15 is connected to the quick-change handle 27 through the interface 26.

[0041] Furthermore, the snap-fit ​​connector at the front end of the outer sleeve 17 includes at least two snap-fit ​​springs 28. The snap-fit ​​springs 28 are distributed in the circumferential direction at the end of the outer sleeve 17. The rear end of the snap-fit ​​springs 28 is connected to the outer sleeve 17. The outer side of the front end of the snap-fit ​​springs 28 is provided with a protruding snap-fit ​​protrusion 29. The snap-fit ​​of the inner support block 8 is realized by the cooperation between the snap-fit ​​protrusion 29 and the snap-fit ​​springs 28. After the screw is inserted, the snap-fit ​​springs can be opened and snapped into the groove on the outer expansion block. After the screw is pulled out, they can be retracted inward, disengaged from the groove, and pulled out.

[0042] In use, the following steps are taken: First, insert the snap-fit ​​connector of the outer sleeve 17 into the inner support block 8 to hold the inner support block 8. Then, use the screw 15 to tighten the screw thread on the outer expansion block 30. At this time, the outer sleeve 17 can be rotated to adjust whether the direction of the inner support block 8 is aligned with the cavity direction of the outer expansion block (before the locking block 19 and the fixing teeth 20 of the inner sleeve 16 engage, the inner and outer sleeves 17 can rotate relative to the screw 15 simultaneously. Because the inner and outer sleeves 17 are flat, they can only move back and forth and cannot rotate relative to each other). After alignment, the locking block 19 is pushed forward from the rear ball groove 22 of the screw 15 to the front ball groove 22, so that the locking block 19 engages with the fixing teeth 20 of the inner sleeve 16, thereby locking the screw 15 and the inner and outer sleeves 17 so that they cannot rotate relative to each other. Rotate the knob 18, knob 1 8. Advance the outer sleeve 17 along the thread of the inner sleeve 16, thereby pushing the inner support block 8 into the outer expansion block 30. The internal meshing teeth on the inner support block are engaged with the fusion anti-disengagement teeth on the outer expansion block. Rotate the screw 15 in the opposite direction to separate the screw 15 from the outer expansion block 30. Pull out the screw 15. The inner sleeve 16 is in a hollow state, and bone grafting can be performed on the expandable fusion device through the hollow hole. The materials of the inner support block 8 and the connecting rod can be titanium alloy (Ti6Al4V), Peek (polyether ether ketone), ultra-high molecular weight polyethylene, etc., which are close to the elastic modulus of bone and are easy to fuse with human bone. When in use, the product fusion device block and connecting rod are made of titanium alloy, and the pushing block can be made of Peek (polyether ether ketone); the product fusion device block and connecting rod are made of Peek (polyether ether ketone), and the pushing block can be made of titanium alloy, etc., in combination. Alternatively, the product fusion block and connecting rod can be made of titanium alloy, while the propulsion block can be made of ultra-high molecular weight polyethylene; or the product fusion block and connecting rod can be made of Peek (polyether ether ketone), while the propulsion block can be made of ultra-high molecular weight polyethylene, etc. In particular, the left and right connecting rods 6 of this patent are elastic arc plates, so they can form a connection between fusion units and at the same time buffer the pressure borne by the fusion unit after implantation. Moreover, the inner support block 8 has support ribs 9 on both sides, which can effectively support the fusion unit and relieve the pressure borne by the fusion unit. The holder of this patent is used in conjunction with the fusion unit of this patent. The outer tube of the holder is fixed on the inner support block, and the screw is fixed on the outer expansion block. It pushes the inner support block into place by pushing the outer tube. The pushing process is stable and the fusion unit will not be displaced due to the knob force generated by the rotation of the screw. Moreover, due to the above structure, this invention has the advantages of simple structure, stability after expansion, high strength after expansion, and easy implantation.

Claims

1. A device assembly for retrieving an expandable interbody fusion cage, comprising an interbody fusion cage and a retrieval device, characterized in that... The intervertebral fusion device includes an inner support block and an outer expansion block. The outer expansion block comprises four strip blocks: a lower left strip block, an upper left strip block, an upper right strip block, and a lower right strip block. The four strip blocks have an L-shaped cross-section and are interlocked to form an outer expansion block assembly with a supporting cavity. After interlocking, the outer expansion block has external meshing teeth on its upper and lower sides. Left and right connecting rods are provided between the lower left and upper left strip blocks, and between the lower right and upper right strip blocks. The upper and lower ends of the left and right connecting rods are respectively connected to the lower left and upper left strip blocks, and the lower right and upper right strip blocks. The upper strip blocks are hinged together. Upper and lower connecting rods are provided between the upper left and upper right strip blocks, and between the lower left and lower right strip blocks. The left and right ends of the upper and lower connecting rods are respectively hinged to the upper left and upper right strip blocks, and the lower left and lower right strip blocks. An inner support block is inserted into the support cavity via a holder. The inner support block opens the four strip blocks after they are limited and rotated by the upper and lower connecting rods and the left and right connecting rods. The front end of the inner support block has an arc-shaped guide head, and the inner support block has a snap-fit ​​hole for connection with the holder. The middle part of the left and right connecting rods is a flexible arc-shaped plate that bends outwards. The inner support block has protruding support ribs on its left and right sides to support the upper and lower strip blocks. The holder includes a screw, an inner sleeve, an outer sleeve, a knob, and a locking block. The front end of the outer sleeve has a snap-fit ​​connector that engages with the inner support block in the fusion device. The inner sleeve is located inside the outer sleeve and is slidably connected to the outer sleeve without rotation. The rear end of the inner sleeve extends out of the outer sleeve and is threadedly connected to the knob. The rear end face of the inner sleeve has fixing teeth. The screw is inserted into the inner sleeve, with the front end of the screw extending out of the outer sleeve and the rear end of the screw extending out of the inner sleeve and having a locking block. The front end face of the locking block has... The locking teeth mesh with the fixed teeth to achieve non-rotation locking of the screw, inner sleeve, and outer sleeve. The rear end of the screw has at least two ball grooves along the screw axis. The locking block has a ball mounting hole, in which a ball, a spring, and a sealing cap are installed. The ball is connected to the sealing cap via the spring, and the sealing cap is fixed to the ball mounting hole. The front end of one of the lower left strip block, upper left strip block, upper right strip block, and lower right strip block has a baffle plate, which is perpendicularly connected to the strip block. The baffle plate has a connecting screw hole for connecting a gripper.

2. The device assembly for holding and expanding interbody fusion device according to claim 1, characterized in that... The inner support block is provided with internal meshing teeth at both ends. The inner wall of the L-shaped strip block is provided with fusion anti-detachment teeth that cooperate with the internal meshing teeth. The fusion anti-detachment teeth have individual teeth in the internal meshing teeth that are inclined to the rear side and individual teeth in the fusion anti-detachment teeth that are inclined to the front side. The internal meshing teeth and the fusion anti-detachment teeth are meshed together and fixed as a whole.

3. The device assembly for holding and expanding interbody fusion device according to claim 1, characterized in that... The upper and lower ends of the left and right connecting rods are respectively provided with left and right clearance grooves on the corresponding strip blocks. A connecting post is provided in the left and right clearance grooves. A connecting ring is provided at the upper and lower ends of the left and right connecting rods respectively. The upper and lower ends of the left and right connecting rods are connected to the connecting post through the connecting rings to achieve the hinge connection between the left and right connecting rods and the strip blocks.

4. The device assembly for holding and expanding interbody fusion device according to claim 1, characterized in that... The upper and lower connecting rods are provided with upper and lower clearance grooves on the corresponding strip blocks at their left and right ends, and connecting posts are provided in the upper and lower clearance grooves. Connecting rings are provided at the upper and lower ends of the upper and lower connecting rods, and the upper and lower connecting rods are hinged to the strip blocks by inserting the connecting rings into the connecting posts at their left and right ends.

5. The device assembly for holding and expanding interbody fusion device according to claim 1, characterized in that... The inner support block has internal locking teeth on its left and right rear ends respectively. The inner wall of the L-shaped strip block has a lateral anti-detachment tooth group that cooperates with the internal locking teeth. When the inner support block moves forward, the internal locking teeth are inserted into the lateral anti-detachment tooth group in sequence to achieve anti-detachment locking.

6. The device assembly for holding and expanding interbody fusion device according to claim 1, characterized in that... The screw has a guide profile, and the locking block has a guide groove that mates with the guide profile. The screw slides within the locking block without rotating, thanks to the mate between the guide profile and the guide groove. The rear end of the screw has an interface that mates with the quick-change handle. The screw is connected to the quick-change handle through the interface.

7. The device assembly for holding and expanding interbody fusion device according to claim 1, characterized in that... The snap-fit ​​connector at the front end of the outer tube includes at least two snap-fit ​​springs, which are distributed in the circumferential direction at the end of the outer tube. The rear end of the snap-fit ​​spring is connected to the outer tube, and the outer side of the front end of the snap-fit ​​spring is provided with a protruding snap-fit ​​head. The snap-fit ​​of the inner support block is achieved by the cooperation between the snap-fit ​​head and the snap-fit ​​spring.

Images