Internal fixation screw for orthopedics department, screw taking-out device and taking-out method

Abstract

The invention discloses an orthopedic internal fixation screw, a screw taking-out device and a screw taking-out method. The screw comprises a stud and a nut, the stud is provided with a first-stage rod body and a second-stage rod body, the nut is provided with a first groove type, a shaft rod and a second groove type are arranged above the second-stage rod body, and the first-stage rod body is provided with a threaded through groove. The thread through groove part is provided with an internal thread and a shaft rod external thread to form a thread connection structure, and the thread pitch is different from that of the stud external thread. A tension spring, a locking block and other structures are further arranged. The screw taking-out device comprises a shaft seat, a screw tap, a first-stage screwdriver, a second-stage screwdriver, an elastic telescopic component and the like, and the wrench is used for driving the shaft seat to rotate. The screw is reasonable in structural design, the contact stress of sclerotin and threads can be uniformly distributed when the screw is screwed in, the resistance change is stable when the screw is taken out, and damage to surrounding tissues and sclerotin is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to an orthopedic internal fixation screw, a screw removal device and a removal method thereof. Background Art

[0002] Internal fixation is a surgical procedure used to treat fractures, dislocations or certain bone diseases by implanting metal or other material devices (such as plates, screws, pins, wires, intramedullary nails, etc.) into the body to fix bones or joints in order to promote fracture healing or restore the stability of the bone structure.

[0003] Orthopedic internal fixation screws currently have a variety of specifications and models, aiming to improve surgical accuracy, reduce surgical trauma, enhance screw stability and speed up patient recovery, such as by increasing screw diameter and length, improving screw structure design, using screw reinforcement materials, etc. to improve screw fixation strength. For example,

[0004] Chinese patent publication number: CN105167835A, relates to a locking screw, including a nail cap and a nail rod, on which a nail cap thread and a nail rod thread are respectively provided, the nail cap thread matches the threaded hole on the locking plate, the nail cap thread is a double-headed tapered variable lead thread, the lead of the nail cap thread changes from small to large from the nail rod to the nail cap, and the axial displacement difference is generated between the starting end thread and the ending end through the lead change of the screw rotation. To eliminate the play gap between the screw and the locking plate thread along the axial direction of the screw, increase the self-locking force of the screw to prevent loosening, and ensure the necessary stability of the locked internal fixation, so that a certain degree of enhancement is achieved in the fixation. However, when removing the internal fixation screw, due to the change in the thread lead and the close combination with the bone, it is necessary to overcome a large resistance, thereby generating a large force on the surrounding bone, which is easy to cause the healed bone to be damaged, causing the local bone to bear excessive pressure, and then causing bone damage.

[0005] Chinese patent publication number: CN111184563A, relates to a fracture internal fixation screw, including a screw body and a screw cap, characterized in that the screw body and the screw cap both include a metal part and an absorption part, the absorption part is a biodegradable material absorption part or a biodegradable material and an inorganic material blend absorption part, the metal part and the absorption part are fixedly connected as an integral structure, and the absorption part at least wraps a part of the metal part. Made of degradable biomedical materials such as PLA and magnesium alloy, it has the advantage of not requiring secondary surgery for removal, but there are problems of high failure rate and possible rejection reaction.

[0006] Therefore, designing an orthopedic internal fixation screw that can provide stable and reliable effects during the fixation phase and reduce bone damage to the patient during removal has become an important research direction in the current orthopedic field. Summary of the invention

[0007] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide an orthopedic internal fixation screw with a reasonable structural design, aiming to effectively solve the problems of unstable fixation effect of the existing internal fixation screws during use and easy bone damage during removal.

[0008] The technical solution adopted by the present invention to solve the above-mentioned problem is: an orthopedic internal fixation screw, including a stud and a nut, the stud includes a primary rod body and a secondary rod body, the nut is arranged at the end of the primary rod body and has a first groove type, a shaft rod is arranged above the secondary rod body, and a second groove type is opened at the end of the shaft rod, the primary rod body has a threaded through groove adapted to the sliding and threaded connection of the shaft rod, the threaded through groove passes through the stud and the nut, and the cross-section of the threaded through groove is smaller than the first groove type of the nut.

[0009] Preferably: the end of the threaded through groove away from the nut is provided with a partial internal thread, and the outer surface of the shaft rod close to the secondary rod body is provided with an external thread compatible with the internal thread structure to form a threaded connection structure, and the pitch of the threaded connection structure is different from the pitch of the external thread of the stud, and the external thread of the stud includes a first thread segment arranged on the outside of the primary rod body and a second thread segment arranged on the outside of the secondary rod body, and the pitch of the second thread segment is the same as that of the first thread segment.

[0010] Preferably, the pitch of the threaded connection structure increases gradually and continuously from the stud nut to the stud head, and the pitch of the initial segment is the same as the first thread segment.

[0011] Preferably, the threaded connection structure adopts a sawtooth thread, and the working surface of the sawtooth thread faces the pressure side.

[0012] Preferably: a tension spring is passed through the threaded through groove, and a shoulder structure is provided at the intersection of the nut and the stud. The shoulder structure makes the cross-section of the threaded through groove at the nut smaller than the cross-section at the primary rod body. The tension spring is arranged between the shoulder and the end of the shaft rod, one end of which is fixedly connected to the end of the shaft rod, and the other end is rotatably connected to the shoulder. The tension spring pulls the shaft rod so that the external thread of the shaft rod contacts the internal thread of the threaded through groove.

[0013] Preferably: the threaded through groove is symmetrically provided with a locking block on the inner wall of the primary rod body, the end of the shaft rod is provided with a locking head, the outer side of the locking head is provided with an arc-shaped locking groove that is slidably adapted to the locking block, the locking groove includes a locking section and an unlocking section, the unlocking section is open at the end face of the locking head and is provided with a corner at the transition with the locking section, and the locking section is provided with a flat cutoff end.

[0014] The present invention also provides a screw removal device for the above-mentioned orthopedic internal fixation screw, comprising a shaft seat for driving the screw to rotate, one end of the shaft seat is connected and fixed with a tap, and the other end is connected with a primary knife batch adapted to the first groove of the primary rod body and a secondary knife batch adapted to the second groove of the secondary rod body, the primary knife batch is sleeved on the outside of the secondary knife batch and the secondary knife batch extends out of the primary knife batch, and the outer diameter of the secondary knife batch is smaller than the inner diameter of the through groove at the nut;

[0015] The first-level knife batch is slidably connected to the shaft seat through an elastic telescopic component. The elastic telescopic component includes a plurality of guide rods circumferentially arranged on the first-level knife batch and a compression spring sleeved on the outside of the guide rod. The guide rod is slidably connected and adapted with a corresponding slide groove opened on the shaft seat, and both ends of the compression spring are respectively connected and fixed to the shaft seat and the first-level knife batch.

[0016] Preferably: it also includes a wrench for driving the shaft seat to rotate, the wrench includes a lever, the lever is provided with a mounting hole for fixing the shaft seat, two ends of the lever are respectively provided with a gripping end and a threaded end, the threaded end is penetrated by a tapered rod, an end of the tapered rod away from the threaded end is sleeved with a threaded sleeve, the threaded sleeve is threadedly connected to the threaded end of the lever, one end of the tapered rod passing through the threaded end and extending out of the mounting hole is provided with a clamping block, and the other end is provided with a push block adapted to the inner end surface contour of the threaded sleeve, the tapered rod sleeve is provided with a reset spring, the reset spring is located between the threaded end of the lever and the push block, and the reset spring pushes the push block to fit tightly against the inner end surface of the threaded sleeve after the threaded sleeve is connected to the lever.

[0017] Preferably: a limit groove is provided at the threaded end of the lever, a through hole is provided at the tapered rod, a pin is passed through the through hole, both ends of the pin are slidably connected and adapted to the limit groove, and the tapered rod moves axially along the lever within the length of the limit groove without rotating.

[0018] Compared with the prior art, the present invention has the following advantages and effects:

[0019] The present invention divides the screw into a primary rod body and a secondary rod body through a unique structural design. The primary rod body and the secondary rod body are connected and adapted through a threaded connection structure, which includes an external thread of a shaft rod arranged at the end of the secondary rod body and an internal thread of a threaded through groove arranged on the primary rod body. A nut is arranged at the end of the primary rod body away from the secondary rod body, wherein a part of the internal thread arranged at one end of the threaded through groove away from the nut is adapted to the external thread arranged on the outer surface of the secondary rod, and the formed threaded connection structure has a unique pitch design. Among them, the external thread of the stud includes a first thread segment arranged on the outside of the primary rod body and a second thread segment arranged on the outside of the secondary rod body, and the pitch of the second thread segment is the same as that of the first thread segment. First, in the process of screwing the screw into the bone, the uniform distribution of the contact stress between the bone and the external thread of the stud can be ensured. Since the pitch of the two segments of the thread is consistent, there will be no local uneven force caused by the pitch difference during the entire screwing process, thereby ensuring that the combination between the screw and the bone is more stable and firm. Secondly, from the perspective of clinical application, the same pitch makes it easier for doctors to grasp the screw-in depth and force during the operation, reducing the complexity of the operation caused by the pitch change and reducing the surgical risk. In addition, during the removal of the screws after the fracture heals, the design of the same pitch makes the resistance change during removal relatively stable, reducing the risk of secondary damage to the surrounding tissues and bones, which is beneficial to the patient's recovery. At the same time, a layer of anti-debris film is provided at the first groove of the screw, and the threaded groove below the anti-debris film is filled with gel, which can prevent human tissue from invading the threaded groove, reduce the aging of the secondary rod body (the second groove at the upper end of the shaft), and enable the secondary cutter to penetrate into the threaded groove and effectively cooperate with the second groove, which is helpful for the removal of the screw. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a stereoscopic diagram of an orthopedic internal fixation screw according to embodiment 1 of the present invention.

[0021] Figure 2 It is a cross-sectional view of an orthopedic internal fixation screw according to embodiment 1 of the present invention.

[0022] Figure 3 It is a schematic diagram of the use of an orthopedic internal fixation screw according to Example 1 of the present invention.

[0023] Figure 4 It is a schematic structural diagram of the left-handed threaded connection structure of Example 1 of the present invention.

[0024] Figure 5 It is a schematic diagram of the pitch marking of the threaded connection structure of Example 1 of the present invention.

[0025] Figure 6 It is a schematic structural diagram of the lock groove of the shaft rod lock head in embodiment 1 of the present invention.

[0026] Figure 7 It is a schematic structural diagram of the shaft seat of the screw removal device in Example 2 of the present invention.

[0027] Figure 8 It is a schematic structural diagram of the elastic telescopic component of Example 2 of the present invention.

[0028] Fig. 9 It is a cross-sectional view of the shaft seat of the screw removal device according to embodiment 2 of the present invention.

[0029] Fig.10 It is a schematic diagram of the structure of the screw removal device wrench according to embodiment 2 of the present invention.

[0030] Fig.11 It is a schematic diagram of a wrench mounting hole fixing shaft seat in embodiment 2 of the present invention.

[0031] Fig.12 It is a schematic diagram of the use of the screw removal device in embodiment 3 of the present invention.

[0032] Fig.13 It is a partially enlarged schematic diagram of an orthopedic internal fixation screw according to Example 3 of the present invention.

[0033] Fig.14 It is a schematic diagram of the principle of opening a new threaded hole at the second groove of the tap in Example 3 of the present invention.

[0034] Figure numbers: stud 11, nut 12, primary rod body 13, secondary rod body 14, first groove type 15, shaft rod 16, second groove type 17, threaded through groove 18, threaded connection structure 21, first thread segment 22, second thread segment 23, tension spring 24, shoulder structure 25, locking block 31, locking head 32, locking groove 33, locking segment 34, unlocking segment 35, corner 36, cut-off end 37, shaft seat 41, tap 42, primary cutter batch 43, secondary cutter batch 44, elastic telescopic component 51, guide rod 5 2, compression spring 53, slide groove 54, adjusting knob 61, movable sleeve 62, fixed sleeve 63, annular groove 64, retaining ring 65, wrench 7, lever 71, mounting hole 711, gripping end 712, threaded end 713, limiting groove 714, tapered rod 72, clamping block 721, push block 722, through hole 723, screw sleeve 73, return spring 74, pin 75, fixed section 81, inclined surface 82, arc surface 83, anchor point 84, anti-debris film 85, gel 86, steel plate 87, sleeve 88, connecting spring 89. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0036] Embodiment 1:

[0037] See also Figure 1and Figure 2 In this embodiment, an orthopedic internal fixation screw includes a stud 11 and a nut 12. The stud 11 includes a primary rod body 13 and a secondary rod body 14. The nut 12 is arranged at the end of the primary rod body 13 and has a first groove 15. A shaft 16 is arranged above the secondary rod body 14, and a second groove 17 is provided at the end of the shaft 16. The primary rod body 13 has a threaded through groove 18 adapted for sliding and threaded connection with the shaft 16. The threaded through groove 18 runs through the stud 11 and the nut 12, and the cross-section of the threaded through groove 18 is smaller than the first groove 15 of the nut 12.

[0038] Specifically, in this embodiment, the stud 11 is composed of a primary rod body 13 and a secondary rod body 14 that are slidably connected. The nut 12 is disposed at the end of the primary rod body 13 and is provided with a first groove 15. The end of the shaft rod 16 above the secondary rod body 14 is provided with a second groove 17, which is convenient for cooperation with the installation tool. The threaded through groove 18 provided on the primary rod body 13 and adapted for threaded connection with the shaft rod 16 runs through the stud 11 and the nut 12, and the cross section of the threaded through groove 18 is smaller than the first groove 15 of the nut 12, so that the installation tool can pass through the first groove 15 of the nut 12 and then cooperate with the second groove 17 of the shaft rod 16 along the threaded through groove 18, so as to realize the separate installation of the secondary rod body 14. First, after confirming the drilling depth S through the secondary rod, drill into the primary rod body 13 to expose its nut 12. Assuming that the drilling depth of the primary rod body 13 is a fixed value S1, the length of the secondary rod is C2, and the adjustment range of the extension length S2 of the shaft rod 16 relative to the threaded through groove 18 is between F1 and F2 (i.e., F1<S2<F2), the drilling depth of the screw S=S1+C2-S2, and its range is S1+C2-F2<S<S1+C2-F1, which is suitable for the situation where multiple bone fragments are formed due to comminuted fracture of the bone end, see Figure 3 The bone fragments on one side are fixed to the main bone trunk by the primary rod body 13, and the bone fragments on the other side are fixed to the main bone trunk by the secondary rod body 14. At the same time, multiple groups of screws can be nailed in to achieve all-round fixation of the fracture site.

[0039] In this embodiment, the part of the internal thread set at one end of the threaded through groove 18 away from the nut 12 is adapted to the external thread set on the outer surface of the secondary rod body 14, and the formed threaded connection structure 21 has a unique pitch design. Among them, the external thread of the stud 11 includes a first thread segment 22 set on the outside of the primary rod body 13 and a second thread segment 23 set on the outside of the secondary rod body 14, and the pitch of the second thread segment 23 is the same as the first thread segment 22. First, in the process of screwing the screw into the bone, the uniform distribution of the contact stress between the bone and the external thread of the stud 11 can be guaranteed. Since the pitch of the two sections of the thread is consistent, there will be no local uneven force caused by the difference in pitch during the entire screwing process, thereby ensuring that the combination between the screw and the bone is more stable and firm. Secondly, from the perspective of clinical application, the same pitch makes it easier for doctors to grasp the screwing depth and strength of the screw during operation, reducing the complexity of the operation caused by the pitch change and reducing the risk of surgery. In addition, during the screw removal process after fracture healing, the design of the same pitch makes the resistance change during removal relatively smooth, reducing the risk of secondary damage to surrounding tissues and bones, and is beneficial to the patient's recovery.

[0040] See also Figure 5 Specifically, the external thread (the first thread segment 22 and the second thread segment 23) of the stud 11 in this embodiment is right-handed, and the pitch of the threaded connection structure 21 gradually increases from the nut 12 of the stud 11 to the head of the stud 11, and the pitch of the initial segment is the same as the first thread segment 22. The pitch of the initial segment is D, and the subsequent pitches are 1.1D, 1.2D, 1.3D, ..., respectively. The pitch of the external thread of the stud 11 is also D. The threaded connection structure 21 (relative to the direction in which the shaft 16 is screwed into the threaded through groove 18) can be left-handed or right-handed, see Figure 1 and Figure 2 .

[0041] See also Figure 4 When the threaded connection structure 21 is left-handed, by screwing the primary rod body 13 in the forward direction, the shaft rod 16 is screwed into the threaded through groove 18 through the threaded connection structure 21. Since the pitch of the threaded connection structure 21 gradually increases with the increase of the screwed-in length of the shaft rod 16, the pitch of the second thread segment 23 is constant, that is, the speed at which the second rod body is screwed into the bone remains unchanged, so that the screwing-in speed of the shaft rod 16 is gradually greater than the screwing speed of the second rod body. At this time, the shaft rod 16 is subjected to axial forces on both sides, one side is the connection between the bone and the second thread segment 23 of the second rod body, and the other side is the threaded connection structure 21 of the shaft rod 16 and the threaded through groove 18 of the first rod body. The two connections are tightened by the shaft rod 16 to form a pre-tightening force for locking and fixing.

[0042] Similarly, see Figure 2When the threaded connection structure 21 is right-handed, the first-stage rod body 13 is screwed forward so that the shaft rod 16 and the threaded groove 18 are about to be screwed in, that is, when the thread surface of the threaded connection structure 21 is just screwed in, the second-stage rod body 14 can be screwed back slightly by screwing it in the reverse direction, and then the first-stage rod body 13 is screwed forward to screw part of the shaft rod 16 into the threaded groove 18. The axial preload force generated by the shaft rod 16 tightens the first rod body and the second rod body against each other, and the bone is squeezed inward by the thread surfaces on both sides (the first thread segment 22 and the second thread segment 23), thereby increasing the friction and bite force between the thread and the bone, making the screw more firmly anchored in the bone or joint.

[0043] In this embodiment, the displacement difference generated during the screw locking process can eliminate the play gap between the screw and the bone thread along the axial direction of the screw, increase the self-locking force of the screw to prevent loosening, and ensure the necessary stability of locked internal fixation. The pitch of the first thread segment 22 is equal to the pitch of the second thread segment 23, so that the nailing speed of the first rod body and the nailing speed of the second rod body are synchronized, ensuring the relative gap between the external thread of the screw and the bone joint surface, and retaining the blood supply of the bone joint surface. The threaded connection structure 21 adopts a serrated thread, and the working edge of the serrated thread is close to a rectangular straight edge, which can be used to withstand unidirectional axial force. During the bone healing process, it can effectively bear the axial tension of the fracture site and reduce the loosening or deformation of the screw. At the same time, the design of the rectangular straight edge increases the contact area between the thread and the bone tissue, disperses the stress, and reduces the damage to the bone tissue caused by excessive local pressure.

[0044] In this embodiment, a tension spring 24 is inserted into the threaded through groove 18, and a shoulder structure 25 is provided at the intersection of the nut 12 and the stud 11 of the threaded through groove 18. The shoulder structure 25 makes the cross section of the threaded through groove 18 at the nut 12 smaller than the cross section at the primary rod body 13. The tension spring 24 is provided between the shoulder and the end of the shaft rod 16, which can prevent the shaft rod 16 from coming out of the threaded through groove 18. One end of the tension spring 24 is connected and fixed to the end of the shaft rod 16, and the other end is rotatably connected to the shoulder, so that when the shaft rod 16 is rotated and adjusted, the tension of the tension spring 24 is not affected. At the same time, the rotation connection also reduces the twisting damage of the tension spring 24 caused by screwing the primary rod body 13 or the secondary rod body 14 alone. In addition, under the tension of the tension spring 24, the tension spring 24 pulls the shaft rod 16 so that the external thread of the shaft rod 16 contacts the internal thread of the threaded through groove 18. During long-term use of the screw for fixation, even if the threaded connection structure 21 is slightly worn, the tension of the tension spring 24 can compensate for the gap caused by the wear and maintain the fastening performance between the external thread of the shaft 16 and the internal thread of the threaded groove 18, thereby extending the service life of the screw and providing a more stable and lasting fixation guarantee for the healing of fractures.

[0045] See also Figure 6In this embodiment, the shaft 16 of the stud 11 in the initial state extends outward to the longest state. At this time, the shaft 16 is locked in the threaded groove 18. On the one hand, it can prevent the shaft 16 from sliding in the threaded groove 18 and causing wear during storage and transportation of the screw. On the other hand, it can allow medical staff to observe whether the external thread of the shaft 16 is worn before use. Specifically, the threaded groove 18 is symmetrically provided with a locking block 31 on the inner wall of the primary rod body 13, and a locking head 32 is provided at the end of the shaft 16. The locking head 32 is slidably adapted to the non-internal thread section of the threaded groove 18 and an arc-shaped locking groove 33 is slidably adapted to the locking block 31 on its outer side. The locking groove 33 includes a locking section 34 and a unlocking section 35. The unlocking section 35 is open at the end face of the locking head 32 and is provided with a corner 36 at the transition point with the locking section 34. The locking section 34 is provided with a flat cutoff end 37. In this embodiment, the locking block 31 and the locking groove 33 are arranged counterclockwise, and the second threaded section 23 is a positive thread (right-handed), so when the secondary rod body 14 is rotated and drilled in the positive direction (clockwise), the locking head 32 is always at the cut-off end 37 of the locking groove 33, and remains locked. Only when the locking head 32 rotates in the opposite direction (counterclockwise) relative to the threaded through groove 18, the locking block 31 can be disengaged from the locking groove 33. Specifically, the locking head 32 first slides from the cut-off end 37 along the locking section 34 to the corner 36, at which time the tension spring 24 is stretched. When the locking head 32 continues to slide until it slides out of the corner 36, under the tension of the tension spring 24, the locking head 32 slides along the unlocking section 35 and finally disengages from its open position, thereby unlocking the shaft rod 16. Through the design of the locking structure, the doctor can realize synchronous drilling and fixing of the primary rod body 13 and the secondary rod body 14 by only using the installation tool in conjunction with the second groove 17 to screw forward (clockwise) when the shaft 16 is not unlocked, thereby improving the efficiency of the screw fixing operation. In addition, the secondary rod body 14 and the primary rod body 13 can be screwed forward (clockwise) in sequence when the shaft 16 is unlocked, and the secondary rod body 14 and the primary rod body 13 are fixed twice in succession, which can reduce the resistance during a single drilling into the affected area (fracture site), and correspondingly reduce the pressure applied by the doctor to the screw, which helps to more accurately control the screw fixing process and avoid damage to surrounding tissues due to excessive pressure.

[0046] Embodiment 2:

[0047] See also Figure 7 - Fig. 9The present invention also provides a screw removal device for the above-mentioned orthopedic internal fixation screw, comprising a shaft seat 41 for driving the screw to rotate, one end of the shaft seat 41 is connected and fixed with a tap 42, and the other end is connected with a primary knife batch 43 adapted to the first groove type 15 of the primary rod body 13 and a secondary knife batch 44 adapted to the second groove type 17 of the secondary rod body 14, the primary knife batch 43 is sleeved on the outside of the secondary knife batch 44 and the secondary knife batch 44 extends out of the primary knife batch 43, and the outer diameter of the secondary knife batch 44 is smaller than the inner diameter of the through groove at the nut 12;

[0048] The first-level knife batch 43 is slidably connected to the shaft seat 41 through an elastic telescopic component 51. The elastic telescopic component 51 includes a plurality of guide rods 52 circumferentially arranged on the first-level knife batch 43 and a compression spring 53 sleeved on the outside of the guide rods 52. The guide rods 52 are slidably connected and adapted with corresponding slide grooves 54 opened on the shaft seat 41. The two ends of the compression spring 53 are respectively connected and fixed to the shaft seat 41 and the first-level knife batch 43.

[0049] Specifically, in this embodiment, an adjusting knob 61 for adjusting the length of the primary knife batch 43 is provided. The adjusting knob 61 includes a movable sleeve 62 that is rotatably sleeved on the outside of the shaft seat 41 and a fixed sleeve 63 that is fixed on the outside of the primary knife batch 43. The internal thread of the movable sleeve 62 is connected and adapted to the external thread of the fixed sleeve 63. The inner side of the movable sleeve 62 is provided with an annular groove 64. The outer side of the shaft seat 41 is provided with a retaining ring 65. The movable sleeve 62 does not detach from the shaft sleeve when rotating. By rotating the movable sleeve 62 to adjust the thread engagement length between it and the fixed sleeve 63, the length of the compression spring 53 of the elastic telescopic component 51 after being compressed is changed, and the length of the primary knife batch 43 is adjusted, thereby changing the extension length of the secondary knife batch 44 relative to the primary knife batch 43. Specifically, in this embodiment, the initial length of the primary knife batch 43 is L1, and the length of the secondary knife batch 44 is fixed to L2. At this time, the extension length L3 of the secondary knife batch 44 relative to the primary knife batch 43 is L2-L1. The adjustment knob 61 drives the length of the elastic telescopic component 51 to change by ΔL, so that the length of the primary knife batch 43 becomes L1'=L1+ΔL. At this time, the extension length of the secondary knife batch 44 relative to the primary knife batch 43 is L3'=L2-L1'=L3-ΔL. Therefore, the extension length of the secondary knife batch 44 relative to the primary knife batch 43 can be changed by adjusting the length of the elastic telescopic component 51, so as to realize the switching between the primary knife batch 43 and the secondary knife batch 44.

[0050] See also Fig.10 and Fig.11The screw removal device in this embodiment also includes a wrench 7 for driving the shaft seat 41 to rotate. The wrench 7 includes a lever 71, the lever 71 is provided with a mounting hole 711 for fixing the shaft seat 41, and the two ends of the lever 71 are respectively provided with a gripping end 712 and a threaded end 713, the threaded end 713 is penetrated by a tapered rod 72, and the end of the tapered rod 72 away from the threaded end 713 is sleeved with a screw sleeve 73, the screw sleeve 73 is threadedly connected with the threaded end 713 of the lever 71, and the end of the tapered rod 72 that passes through the threaded end 713 and extends out of the mounting hole 711 is provided with a clamping block 721, and the other end is provided with a push block 722 adapted to the inner end surface contour of the screw sleeve 73, the tapered rod 72 is sleeved with a reset spring 74, the reset spring 74 is located between the threaded end 713 of the lever 71 and the push block 722, and the reset spring 74 pushes the push block 722 to be close to the inner end surface of the screw sleeve 73 after the screw sleeve 73 is connected to the lever 71. The threaded end 713 of the lever 71 is provided with a limit groove 714, and the tapered rod 72 is provided with a through hole 723, through which a pin 75 is passed, and the end of the pin 75 is slidably connected and adapted to the limit groove 714, and the tapered rod 72 moves axially along the lever 71 within the length range of the limit groove 714 and does not rotate. The extension length of the clamping block 721 relative to the mounting hole 711 can be adjusted by rotating the screw sleeve 73. For example, increasing the extension length of the clamping block 721 is used. Specifically, the screw sleeve 73 is manually driven to rotate, and the threaded engagement length between the screw sleeve 73 and the threaded end 713 of the lever 71 increases. The inner end surface of the screw sleeve 73 pushes the push block 722 of the tapered rod 72. At this time, the reset spring 74 contracts, and the clamping block 721 of the tapered rod 72 extends toward the mounting hole 711, which can be used to fix the shaft seat 41 in the mounting hole 711.

[0051] When assembling the wrench 7, firstly, the reset spring 74 needs to be inserted from the clamping block 721 end of the conical rod 72, and then the clamping block 721 end of the conical rod 72 is inserted into the threaded end 713 of the lever 71, so that the through hole 723 of the conical rod 72 is aligned with the limiting groove 714, and then the pin 75 is inserted, and then the screw sleeve 73 is connected to the threaded end 713 of the lever 71. The shaft seat 41 can also be installed on the wrench 7 for use, so it needs to be fixed. Firstly, the shaft seat 41 needs to be partially inserted into the mounting hole 711 of the wrench 7, and the screw sleeve 73 is rotated to push the push block 722 of the conical rod 72, and the clamping block 721 of the conical rod 72 is pushed toward the shaft seat 41, and the shaft seat 41 is fixed under the clamping of the inner wall of the mounting hole 711 and the clamping block 721.

[0052] Specifically, in the present embodiment, the shaft seat 41 includes a fixed section 81 with a hexagonal cross-section, and a slope 82 with an angle not exceeding 90° is provided on the side of the mounting hole 711 relative to the clamping block 721, and a curved surface 83 is provided on the side where the clamping block 721 extends out, and the end of the clamping block 721 is an M-shaped tooth structure, and the hexagonal cross-section of the fixed section 81 is clamped by the angle of the slope 82 and the M-shaped tooth structure of the clamping block 721. The hexagonal cross-section design makes it less likely for the shaft seat 41 to rotate when subjected to the torque applied by the wrench 7, thereby improving the clamping stability of the wrench 7 on the shaft seat 41.

[0053] Embodiment 3:

[0054] The present invention also provides a method for removing the orthopedic internal fixation screw described in Example 1 and the screw removal device described in Example 2, see Fig.12 , specifically including the following steps:

[0055] S1, install the screws. When performing orthopedic internal fixation surgery, first determine the drilling position of the screws through imaging examinations such as X-rays and CT scans and actual observations during the operation, and use positioning components (such as Kirschner wires, guides, navigation templates, positioning drill sleeves, etc.) to ensure that the screws can effectively fix the fracture site. Then, drive the tap 42 along the screw drilling direction in the target area by rotating the wrench 7. Then, under the screwing action of the secondary knife batch 44 and the primary knife batch 43 of the shaft seat 41, screw the secondary rod body 14 and the primary rod body 13 of the stud 11 into the screw hole in turn. During the screwing process, always pay attention to the direction and position of the screws to avoid unnecessary damage to the surrounding nerves, blood vessels and tissues;

[0056] Specifically, to achieve the secondary rod body 14 and the primary rod body 13 being screwed into the screw hole in sequence, the length of the primary knife group 43 can be adjusted by adjusting the knob 61, so that the length of the primary knife group 43 is reduced and the extension length of the secondary knife group 44 is increased, so that when the secondary knife group 44 cooperates with the second groove type 17, the primary knife group 43 has not yet contacted the first groove type 15. Under the locking of the shaft rod 16 and the threaded through groove 18, the secondary knife group 44 is rotated to drive the secondary rod body 14 to drill into the screw hole until the secondary rod body 14 drills into the required depth, and the length of the primary knife group 43 is reduced again by using the adjusting knob 61, and the primary knife group 43 is rotated in the reverse direction to unlock the shaft rod 16, and then the primary knife group 43 is rotated forward to drive the primary rod body 13 to drill into the screw hole.

[0057] S2, locking screw, after using the primary knife batch 43 to screw the primary rod body 13 forward to a suitable position for preliminary fixing, use the secondary knife batch 44 to screw the secondary rod body 14 forward, so that the external thread of the shaft rod 16 contacts and cooperates with the internal thread of the threaded through groove 18. Continue to screw the secondary rod body 14, so that the shaft rod 16 is screwed into the threaded through groove 18. Since the pitch of the threaded connection structure 21 there is greater than the pitch of the external thread of the stud 11 (the second threaded section 23 of the secondary rod body 14), the axial displacement at the second threaded section 23 is greater than the axial displacement of the threaded connection structure 21 at the shaft rod 16 and the threaded through groove 18, so that the shaft rod 16 is subjected to axial tension, and the locking between the primary rod body 13 and the secondary rod body 14 is achieved.

[0058] At this time, make sure the screws are tightened to a moderate degree, which can stabilize the fracture ends without causing excessive pressure on the bones. At the same time, reconfirm the position and fixation effect of the screws through X-rays or other imaging equipment;

[0059] S3, remove the screw. When it is necessary to remove the screw, first reversely screw the secondary rod body 14 to screw the external thread of the shaft rod 16 out of the internal thread of the threaded groove 18, and release the locking state between the primary rod body 13 and the secondary rod body 14. Then screw the primary rod body 13 and the secondary rod body 14 out of the screw hole simultaneously or sequentially. In the process of removing the screw, be careful to avoid secondary damage to the bones and surrounding tissues. After removing the screw, clean and suture the wound to promote the patient's recovery. Due to the aging phenomenon of the screw, especially the second groove type 17 of the second rod body with a smaller size, the bone healing is relatively slow, and the threaded groove 18 may be worn or filled with human tissue after long-term retention in the body. It is necessary to use a tap to open the internal thread of the second rod body. The external thread of the tap 42 in this embodiment is opposite to the external thread of the screw, which is left-handed. When drilling, the internal thread is opened counterclockwise by the wrench 7 and the second rod body is removed with the help of the tap 42.

[0060] In addition, to prevent the debris generated during the opening of new threads from falling into the body, when using a screw extraction device, refer to Fig.13 A layer of anti-debris film 85 is provided at the first groove 15 of the screw, and the threaded groove 18 below the anti-debris film 85 is filled with gel 86, which can also prevent the invasion of human tissue, so that the secondary knife batch 44 can penetrate into the threaded groove 18 and effectively cooperate with the second groove 17, which is helpful for the removal operation of the screw.

[0061] Similarly, when the first groove 15 of the first rod body is aged and worn, a tap 42 with a larger specification than the tap 42 used to open the second groove 17 can be replaced to open a new threaded hole at the first groove 15. Fig.14, the screw can also be used to fix the fracture plate 87. At this time, a sleeve 88 can be arranged outside the tap 42, and the sleeve 88 is filled with gel 86. The gel 86 is used to capture the debris generated when the new threaded hole at the first groove 15 is opened. At the same time, the sleeve 88 can prevent the debris from spreading. In addition, the sleeve 88 in this embodiment is transparent and made of transparent material, which is convenient for observing the opening process of the new thread. Specifically, the sleeve 88 is fixed to the connection root of the tap 42 and the shaft seat 41 through the connecting spring 89. When opening the threaded hole, the pressure generated by the contraction of the connecting spring 89 causes the sleeve 88 to be sleeved on the outside of the nut 12 and close to the surface of the steel plate 87, effectively preventing the escape of debris.

[0062] The above contents described in this specification are merely examples of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, as long as they do not deviate from the contents of the present specification or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. An orthopedic internal fixation screw, comprising a stud and a nut, characterized in that: The stud includes a primary rod body and a secondary rod body, the nut is arranged at the end of the primary rod body and has a first groove, an axle is arranged above the secondary rod body, and a second groove is arranged at the end of the axle, the primary rod body has a threaded through groove adapted to the sliding and threaded connection of the axle, the threaded through groove passes through the stud and the nut, and the cross-section of the threaded through groove is smaller than the first groove of the nut.

2. An orthopedic internal fixation screw according to claim 1, characterized in that: The threaded through groove is provided with a partial internal thread at one end away from the nut, and the outer surface of the shaft rod close to the secondary rod body is provided with an external thread compatible with the internal thread structure to form a threaded connection structure. The pitch of the threaded connection structure is different from the pitch of the external thread of the stud. The external thread of the stud includes a first thread segment arranged on the outside of the primary rod body and a second thread segment arranged on the outside of the secondary rod body, and the pitch of the second thread segment is the same as that of the first thread segment.

3. An orthopedic internal fixation screw according to claim 2, characterized in that: The pitch of the threaded connection structure increases gradually and continuously from the stud nut to the stud head, and the pitch of the initial section is the same as the first thread section.

4. The orthopedic internal fixation screw according to claim 3, characterized in that: The threaded connection structure adopts a sawtooth thread, and the working surface of the sawtooth thread faces the pressure side.

5. The orthopedic internal fixation screw according to claim 4, characterized in that: A tension spring is passed through the threaded through groove, and a shoulder structure is provided at the intersection of the nut and the stud. The shoulder structure makes the cross section of the threaded through groove at the nut smaller than the cross section at the primary rod body. The tension spring is arranged between the shoulder and the end of the shaft rod, one end of which is fixedly connected to the end of the shaft rod, and the other end is rotatably connected to the shoulder. The tension spring pulls the shaft rod so that the external thread of the shaft rod contacts the internal thread of the threaded through groove.

6. The orthopedic internal fixation screw according to claim 5, characterized in that: The threaded through groove is symmetrically provided with a locking block on the inner wall of the primary rod body, the end of the shaft rod is provided with a locking head, the outer side of the locking head is provided with an arc-shaped locking groove that is slidably adapted to the locking block, the locking groove includes a locking section and an unlocking section, the unlocking section is open at the end face of the locking head and is provided with a corner at the transition with the locking section, and the locking section is provided with a flat cutoff end.

7. A screw removal device for an orthopedic internal fixation screw according to any one of claims 1 to 6, characterized in that: It includes a shaft seat for driving the screw to rotate, one end of the shaft seat is connected and fixed with a tap, and the other end is connected with a primary knife batch adapted to the first groove of the primary rod body and a secondary knife batch adapted to the second groove of the secondary rod body, the primary knife batch is sleeved on the outside of the secondary knife batch and the secondary knife batch extends out of the primary knife batch, and the outer diameter of the secondary knife batch is smaller than the inner diameter of the through groove at the nut; The first-level knife batch is slidably connected to the shaft seat through an elastic telescopic component. The elastic telescopic component includes a plurality of guide rods circumferentially arranged on the first-level knife batch and a compression spring sleeved on the outside of the guide rod. The guide rod is slidably connected and adapted with a corresponding slide groove opened on the shaft seat, and both ends of the compression spring are respectively connected and fixed to the shaft seat and the first-level knife batch.

8. A screw removal device according to claim 7, characterized in that: It also includes a wrench for driving the shaft seat to rotate, the wrench includes a lever, the lever is provided with a mounting hole for fixing the shaft seat, two ends of the lever are respectively provided with a gripping end and a threaded end, the threaded end is penetrated by a tapered rod, the end of the tapered rod away from the threaded end is sleeved with a threaded sleeve, the threaded sleeve is threadedly connected to the threaded end of the lever, one end of the tapered rod extending through the threaded end and extending out of the mounting hole is provided with a clamping block, the other end is provided with a push block adapted to the inner end surface contour of the threaded sleeve, the tapered rod sleeve is provided with a reset spring, the reset spring is located between the threaded end of the lever and the push block, and the reset spring pushes the push block to fit tightly against the inner end surface of the threaded sleeve after the threaded sleeve is connected to the lever.

9. A screw removal device according to claim 8, characterized in that: The threaded end of the lever is provided with a limiting groove, the tapered rod is provided with a through hole, a pin is passed through the through hole, both ends of the pin are slidably connected and adapted to the limiting groove, and the tapered rod moves axially along the lever within the length of the limiting groove without rotating.

10. A method for removing a screw from a screw removal device according to claim 9, characterized in that: The steps include: S1, installing the screw, first determine the drilling position of the screw by using the positioning component, then drive the tap to open an anchor point in the target area along the screw drilling direction by rotating the wrench, and then screw the secondary rod body and the primary rod body of the stud into the screw hole in sequence under the screwing action of the secondary knife batch and the primary knife batch of the shaft seat; S2, locking screw, use the first-level screwdriver to screw the first-level rod body forward to fix the position, use the second-level screwdriver to screw the second-level rod body forward to make the external thread of the shaft rod contact and cooperate with the internal thread of the threaded groove, continue to screw the second-level rod body to pull the shaft rod, and lock the first-level rod body and the second-level rod body through the threaded connection structure; S3, remove the screw, and reversely rotate the secondary rod body to screw the external thread of the shaft out of the internal thread of the threaded groove. Then screw the primary rod body and the secondary rod body out of the screw holes simultaneously or sequentially.

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