Lag screw and femoral intramedullary nail

Abstract

The present invention provides a tension screw and a femoral intramedullary nail, belonging to the technical field of orthopedic implants. The tension screw comprises a nail body and a sleeve, one end of the sleeve being sleeved onto the nail body. The nail body comprises a main body and a truncated cone, a step being provided between the truncated cone and the main body, and an elastic ring sleeved on the truncated cone. The elastic ring can abut against the step. When not subject to external force, the inner diameter of the elastic ring is greater than the diameter of the small end of the truncated cone, and the thickness of the elastic ring is greater than the gap between the sleeve and the large end of the truncated cone. The outer surface of the elastic ring is provided with multiple rows of first teeth, and the inner wall of the sleeve is provided with multiple rows of second teeth, and the first and second teeth are capable of meshing. When the nail body is subjected to an oblique downward force, the elastic ring contracts under the pressure of the second teeth of the sleeve and slides obliquely downward with the nail body. When the nail body is subjected to an oblique upward force, the elastic ring is restricted by the second teeth of the sleeve and cannot move, and the nail body slides obliquely upward until the elastic ring is squeezed by the sleeve and the large end of the truncated cone.

Description

Technical Field

[0001] The present invention belongs to the technical field of orthopedic implants, and in particular relates to a lag screw and a femoral intramedullary nail. Background Art

[0002] Femoral intramedullary nailing is the preferred treatment option for intertrochanteric fusion of the femoral shaft. Typically, a femoral intramedullary nail consists of a main nail, a lag screw, a locking nail, and a cap. The lag screw is typically in the form of a blade, a screw, or a parent-child nail. During surgery, after the lag screw is implanted, it is impossible to apply pressure to the fracture site. Lag screw penetration is a common problem, and the lag screw and main nail cannot be forcefully fixed after surgery. This is especially true if the fracture site shortens after surgery and cannot be pressurized properly. This prolongs the healing time of the fracture site, causing malunion and reducing the patient's quality of life.

[0003] Conventional femoral intramedullary nails have a simple structure and are unstable in the body. Postoperatively, the lag screw often cuts out of or penetrates the femoral head, or the lag screw retreats, causing the patient to undergo a second surgery and increasing pain. Summary of the Invention

[0004] In view of this, the present invention aims to provide a lag screw, which can achieve slight reciprocating movement between the femoral head and the fracture suture, thereby promoting fracture healing.

[0005] The present invention further provides a femoral intramedullary nail having the above-mentioned lag screw, which is beneficial to promoting fracture healing.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] A lag screw comprising:

[0008] A nail body and a sleeve, wherein one end of the sleeve is sleeved on the nail body, the nail body comprises a main body and a truncated cone, a step is provided between the truncated cone and the main body, an elastic ring is sleeved on the truncated cone, the elastic ring can abut against the step, and when not subject to external force, the inner diameter of the elastic ring is larger than the diameter of the small end of the truncated cone, the thickness of the elastic ring is larger than the gap between the sleeve and the large end of the truncated cone, the outer surface of the elastic ring is provided with multiple rows of first teeth, the inner wall of the sleeve is provided with multiple rows of second teeth, and the first teeth and the second teeth can mesh;

[0009] When the nail body is subjected to a downward oblique force, the elastic ring contracts under the squeezing of the second teeth of the sleeve and slides obliquely downward together with the nail body. When the nail body is subjected to an upward oblique force, the elastic ring is restricted by the second teeth of the sleeve and cannot move, and the nail body slides obliquely upward until the elastic ring is squeezed tightly by the sleeve and the large end of the frustum.

[0010] As a preferred solution of the above-mentioned tension screw, it also includes an activation rod, which is coaxially arranged in the sleeve, one end of the activation rod abuts against the end face of the frustum of the nail body, and the outer wall of the activation rod at the other end is threadedly connected to the inner wall of the sleeve.

[0011] As a preferred solution of the above-mentioned tension screw, the activation rod includes a nut, and the outer wall of the activation rod below the nut is provided with a first threaded section, and the first threaded section is connected to the thread on the flange provided on the inner wall of the sleeve.

[0012] As a preferred solution of the above-mentioned tension screw, a limiting tube is provided in one end of the sleeve, the inner wall of the limiting tube is provided with at least one first plane, the nail body is provided with a second plane that fits with the first plane, and the limiting tube is sleeved on the nail body.

[0013] As a preferred solution of the above-mentioned tension screw, the sleeve includes a distal section, a middle section and a proximal section connected in sequence, the distal section is provided with a tail ring, the tail ring can rotate relative to the distal section, the end face of the tail ring is provided with a circle of third teeth, the side wall of the sleeve is provided with a threaded through hole, the threaded through hole is threadedly connected with an anti-backoff pin, and the thread of the anti-backoff pin is provided with a fourth tooth, and the third teeth are engaged with the fourth teeth.

[0014] As a preferred solution of the above-mentioned tension screw, the outer diameter of the tail ring is the same as the outer diameter of the middle section of the sleeve.

[0015] As a preferred solution of the above-mentioned tension screw, the distal section includes an introduction part, an intermediate part and a connecting part arranged in sequence, the diameter of the intermediate part is smaller than the diameters of the introduction part and the connecting part, and the inner wall of the tail ring is provided with an anti-slip structure that can extend into the intermediate part.

[0016] As a preferred solution of the above-mentioned tension screw, the anti-slip structure is a protrusion with an internal thread, the introduction part is provided with an external thread, and when the tail ring is connected to the distal section, the protrusion is introduced into the middle part through the introduction part.

[0017] As a preferred solution of the above-mentioned tension screw, the anti-slip structure is a foldable elastic member. When the elastic member cooperates with the introduction part, the elastic member is in a folded state. When the elastic member enters the middle part through the introduction part, the elastic member is in an expanded state.

[0018] A femoral intramedullary nail comprises a main nail and the aforementioned lag screw.

[0019] Beneficial effects of the present invention:

[0020] The tension screw of the present invention has an elastic ring provided between the sleeve and the frustum. When the femoral head is subjected to an oblique downward force, the nail body is forced to move obliquely downward, pressing the femoral head downward until the fractured bone suture is closed. When the femoral head is subjected to an oblique upward force, the nail body moves obliquely upward along with the femoral head for a certain distance until the elastic ring is squeezed by the sleeve and the large end of the frustum. The tension screw no longer stretches and the nail body will not move obliquely upward infinitely. Therefore, the tension screw can realize a micro-motion function, which is beneficial to the healing of fractures. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 This is a schematic structural diagram of a lag screw according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic structural diagram of a nail body according to an embodiment of the present invention;

[0024] Figure 3 This is a schematic structural diagram of an elastic ring according to an embodiment of the present invention;

[0025] Figure 4 for Figure 1 A partial enlarged view of point A in the middle;

[0026] Figure 5 This is a schematic structural diagram of the tail ring and the anti-backoff pins in accordance with an embodiment of the present invention;

[0027] Figure 6 Schematic diagram of the structure of the anti-backoff nail in the embodiment of the present invention;

[0028] Figure 7 A schematic longitudinal cross-sectional view of the tail ring in an embodiment of the present invention;

[0029] Figure 8 Schematic diagram of the structure of the sleeve in an embodiment of the present invention;

[0030] Figure 9 This is a schematic structural diagram of an activation rod in an embodiment of the present invention;

[0031] Figure 10 This is a schematic diagram of the structure of the activation rod and the nail body in the embodiment of the present invention;

[0032] Figure 11 Schematic diagram of the structure of the limiting tube in an embodiment of the present invention;

[0033] Figure 12 Schematic diagram of the structure of the main nail in the embodiment of the present invention;

[0034] Figure 13 Schematic diagram of the structure of the main nail and the tension screw in the embodiment of the present invention.

[0035] In the picture:

[0036] 1. Nail body; 11. Main body; 12. Cone; 13. Second plane;

[0037] 2. Sleeve; 21. Distal section; 211. Introduction section; 212. Intermediate section; 213. Connecting section; 22. Middle section; 23. Proximal section; 221. Second tooth; 222. Flange; 223. Threaded through hole;

[0038] 3. Elastic ring; 31. First tooth;

[0039] 4. Activation rod; 41. Nut; 42. First thread segment;

[0040] 5. Limiting tube; 51. First plane; 52. Pin;

[0041] 6. Tail ring; 61. Third tooth; 62. Slot; 63. Anti-slip structure;

[0042] 7. Anti-retraction nail; 71. Fourth tooth;

[0043] 8. Main nail; 81. First interlocking hole; 82. Second interlocking hole; 83. Third interlocking hole. DETAILED DESCRIPTION

[0044] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0045] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0046] like Figure 1-3As shown, this embodiment provides a lag screw comprising a body 1 and a sleeve 2. The sleeve 2 is sleeved over the body 1. The body 1 comprises a main body 11 and a truncated cone 12, with a step provided between the truncated cone 12 and the main body 11. The sleeve 2 comprises a distal section 21, a middle section 22, and a proximal section 23, which are connected in sequence. An elastic ring 3 is sleeved on the frustum 12, and the elastic ring 3 can abut against the step. When not subject to external force, the inner diameter of the elastic ring 3 is larger than the diameter of the small end of the frustum 12, and the thickness of the elastic ring 3 is larger than the gap between the sleeve 2 and the large end of the frustum 12. The outer surface of the elastic ring 3 is provided with multiple rows of first teeth 31, and the inner wall of the sleeve 2 is provided with multiple rows of second teeth 221, and the first teeth 31 and the second teeth 221 can engage with each other; when the nail body 1 is subjected to an oblique downward force, the elastic ring 3 contracts under the extrusion of the second teeth 221 of the sleeve 2, and slides obliquely downward together with the nail body 1. When the nail body 1 is subjected to an oblique upward force, the elastic ring 3 is restricted by the second teeth 221 of the sleeve 2 and cannot move. The nail body 1 slides obliquely upward until the elastic ring 3 is squeezed tightly by the sleeve 2 and the large end of the frustum 12.

[0047] In the tension screw of this embodiment, since an elastic ring 3 is provided between the sleeve 2 and the frustum 12, when the femoral head is subjected to an oblique downward force, the nail body 1 is forced to move obliquely downward, pressing the femoral head downward until the fractured bone suture is closed. When the femoral head is subjected to an oblique upward force, the nail body 1 moves obliquely upward along with the femoral head for a certain distance until the elastic ring 3 is squeezed by the sleeve 2 and the large end of the frustum 12. The tension screw no longer stretches, and the nail body 1 will not move obliquely upward infinitely. Therefore, the tension screw can realize a micro-motion function, which is beneficial to the healing of fractures.

[0048] like Figure 3 As shown, the elastic ring 3 is a wavy annular structure, and its diameter can expand or shrink when subjected to external force.

[0049] like Figure 4-7As shown, the distal section 21 is fitted with a tail ring 6, which is rotatable relative to the distal section 21. A circle of third teeth 61 is formed on the end surface of the tail ring 6. The sidewall of the cannula 2 is provided with a threaded through-hole 223. Specifically, the threaded through-hole 223 is located in the middle section 22 of the cannula 2, extending through both the inner and outer walls of the cannula 2. An anti-backout pin 7 is threadedly connected to the threaded through-hole 223. Fourth teeth 71 are provided on the threads of the anti-backout pin 7, and the third teeth 61 engage with the fourth teeth 71. Rotating the tail ring 6 drives the anti-backout pin 7, thereby enabling axial movement of the anti-backout pin 7 along the threaded through-hole 223. When the lag screw is implanted, the tail ring 6 can be rotated to remove the anti-backout pin 7 from the threaded through-hole 223, preventing the lag screw from backing out. When the lag screw is used in conjunction with the main nail 8, the anti-backout pin 7 can be screwed into the main nail 8. When the lag screw is directly engaged with the femur, the anti-backout pin 7 can be screwed into the bone. When the tension screw is to be removed, the tail ring 6 is rotated in the opposite direction, and the tail ring 6 drives the anti-backward pin 7 to rotate in the opposite direction, and the anti-backward pin 7 can be retracted into the threaded through hole 223. The anti-backward pin 7 of this embodiment can be rotated directly without the use of other external surgical instruments to connect with the anti-backward pin 7, thereby achieving the anti-backward function.

[0050] In this embodiment, the outer diameter of the tail ring 6 is the same as the outer diameter of the middle section 22 of the sleeve 2, which can avoid the integrity of the outer surface of the tension screw.

[0051] In this embodiment, a plurality of slots 62 are further provided on the tail ring 6 , and the operating tool is connected to the slots 62 of the tail ring 6 for operation.

[0052] In this embodiment, if Figure 8 As shown, the distal section 21 of the cannula 2 includes an introduction portion 211, an intermediate portion 212, and a connecting portion 213, which are arranged in sequence. The diameter of the intermediate portion 212 is smaller than the diameters of the introduction portion 211 and the connecting portion 213. The inner wall of the tail ring 6 is provided with an anti-slip structure 63 that can extend into the intermediate portion 212. The anti-slip structure 63 ensures that the tail ring 6 can be mounted on the distal section 21 without slipping and can rotate on the distal section 21.

[0053] like Figure 7 As shown, the anti-slip structure 63 is a protrusion with an internal thread, and the introduction portion 211 is provided with an external thread. When the tail ring 6 is connected to the distal section 21 , the protrusion is introduced into the middle portion 212 through the introduction portion 211 .

[0054] In other embodiments, the anti-slip structure 63 is a foldable elastic member. When the elastic member cooperates with the introduction portion 211, the elastic member is in a folded state. When the elastic member enters the middle portion 212 through the introduction portion 211, the elastic member is in an expanded state. The elastic member can be an elastic sheet with one end connected to the middle portion of the inner wall of the tail ring 6, and the other end can be opened at a certain angle to the inner wall of the tail ring 6 when not subject to external force. When squeezed by the sleeve 2, it can be compressed and folded into the receiving groove of the inner wall of the tail ring 6, so that the tail ring 6 can be smoothly installed in the distal section 21 of the sleeve 2. Since the diameter of the middle portion of the distal section 21 is small, the elastic member opens after entering the middle portion 212 and abuts against the side wall of the middle portion, thereby preventing the tail ring 6 from falling out of the distal section 21. Of course, the elastic member can also have other structural forms.

[0055] like Figure 9 and Figure 10 As shown, the tension screw of this embodiment also includes an activation rod 4, which is coaxially arranged in the sleeve 2, and one end of the activation rod 4 abuts the end face of the frustum 12 of the nail body 1, and the outer wall of the activation rod 4 at the other end is threadedly connected to the inner wall of the sleeve 2. Specifically, the activation rod 4 includes a nut 41, and the outer wall of the activation rod 4 below the nut 41 is provided with a first threaded section 42, and the first threaded section 42 is threadedly connected to the flange 222 provided on the inner wall of the sleeve 2. The activation rod 4 is threadedly connected to the sleeve 2, so that the activation rod 4 can be fixed relative to the sleeve 2, thereby supporting the nail body 1 and avoiding relative sliding between the nail body 1 and the sleeve 2 during the implantation operation.

[0056] like Figure 11 As shown, a limiting tube 5 is disposed within one end of the sleeve 2. The inner wall of the limiting tube 5 is provided with at least one first flat surface 51. The nail body 1 is provided with a second flat surface 13 that aligns with the first flat surface 51. The limiting tube 5 is sleeved onto the nail body 1. The limiting tube 5 is connected to the proximal end 23 of the sleeve 2 via a pin 52. This limiting tube 5 prevents relative rotation between the nail body 1 and the sleeve 2. Specifically, the inner wall of the limiting tube 5 is provided with two opposing and parallel first flat surfaces 51. Accordingly, the nail body 1 is provided with two opposing and parallel second flat surfaces 13.

[0057] like Figure 12 and Figure 13 As shown, this embodiment provides a femoral intramedullary nail, including a main nail 8 and the above-mentioned lag screw.

[0058] The main nail 8 is a hollow structure. A first interlocking hole 81 and a second interlocking hole 82 are provided at the proximal end of the main nail 8, and a third interlocking hole 83 is provided at the distal end of the main nail 8. The first interlocking hole 81 is used to install a tension screw, the second interlocking hole 82 is used for screwing in the anti-backoff nail 7, and the third interlocking hole 83 is used to install a locking nail.

[0059] A locking nail is detachably installed in the third interlocking hole 83, which can lock the main nail 8 to the femoral shaft. A tail cap is detachably installed on the top of the main nail 8, which can prevent soft tissue from growing into the main nail 8 and facilitate the removal operation when the main nail 8 needs to be removed.

[0060] During the implantation process, the main nail 8 can be implanted into the femoral medullary cavity through a preset guide needle. The corresponding tension screw is selected and implanted according to the fracture site and the patient's femoral anatomical morphology. During the implantation of the tension screw, one end of the activation rod 4 abuts against the end face of the frustum 12 of the nail body 1. The activation rod 4 is threadedly connected to the inner wall of the sleeve 2, which can maintain the stability between the nail body 1 and the sleeve 2. The nail body 1 is implanted into the femoral head, and the activation rod 4 is removed. The anti-backoff nail 7 can be driven by rotating the tail ring 6 to lock the nail into the second interlocking hole 82 of the main nail 8, eliminating the step of using external instruments for operation. It is convenient, fast, time-saving and labor-saving. Then, the distal locking nail is implanted to lock the main nail 8 with the femoral shaft, and the normal anatomical morphology of the proximal femoral neck and femoral head is maintained with the help of the strong cortical bone of the shaft. Finally, the tail cap 4 is assembled on the main nail 8 to prevent soft tissue from growing into the main nail 8 and to facilitate the removal operation when the main nail 8 needs to be removed.

[0061] After surgery, the lag screw body 1 and sleeve 2 are in contact with each other via the first flat surface 51 and the second flat surface 13, effectively preventing relative rotation between the body 1 and sleeve 2. Therefore, the body 1 and the main nail 8 do not rotate relative to each other, ensuring fracture healing. Furthermore, after the lag screw is implanted, micro-movement of the fractured femoral head due to gravity or human tension can be achieved through the body 1, sleeve 2, and elastic ring 3, facilitating fracture healing.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A tension screw, characterized in that: include: A nail body (1) and a sleeve (2), wherein one end of the sleeve (2) is sleeved on the nail body (1), and the nail body (1) comprises a main body (11) and a truncated cone (12), wherein a step is provided between the truncated cone (12) and the main body (11), and an elastic ring (3) is sleeved on the truncated cone (12), and the elastic ring (3) can abut against the step. When not subjected to external force, the inner diameter of the elastic ring (3) is larger than the diameter of the small end of the truncated cone (12), and the thickness of the elastic ring (3) is larger than the gap between the sleeve (2) and the large end of the truncated cone (12). The outer surface of the elastic ring (3) is provided with a plurality of rows of first teeth (31), and the inner wall of the sleeve (2) is provided with a plurality of rows of second teeth (221), and the first teeth (31) and the second teeth (221) can mesh; When the nail body (1) is subjected to an oblique downward force, the elastic ring (3) contracts under the pressure of the second teeth (221) of the sleeve (2) and slides obliquely downward together with the nail body (1); when the nail body (1) is subjected to an oblique upward force, the elastic ring (3) is restricted by the second teeth (221) of the sleeve (2) and cannot move, and the nail body (1) slides obliquely upward until the elastic ring (3) is squeezed tightly by the sleeve (2) and the large end of the frustum (12); The sleeve (2) comprises a distal section (21), a middle section (22) and a proximal section (23) connected in sequence, the distal section (21) is sleeved with a tail ring (6), the tail ring (6) can rotate relative to the distal section (21), the end face of the tail ring (6) is provided with a circle of third teeth (61), the side wall of the sleeve (2) is provided with a threaded through hole (223), the threaded through hole (223) is threadedly connected with an anti-backoff pin (7), the thread of the anti-backoff pin (7) is provided with a fourth tooth (71), and the third tooth (61) and the fourth tooth (71) are meshed with each other; The distal section (21) comprises an introduction portion (211), an intermediate portion (212), and a connecting portion (213) arranged in sequence, the diameter of the intermediate portion (212) being smaller than the diameters of the introduction portion (211) and the connecting portion (213), and the inner wall of the tail ring (6) is provided with an anti-slip structure (63) capable of extending into the intermediate portion (212); The anti-slip structure (63) is a foldable elastic member. When the elastic member cooperates with the introduction portion (211), the elastic member is in a folded state. When the elastic member enters the middle portion (212) through the introduction portion (211), the elastic member is in an expanded state.

2. The lag screw according to claim 1, characterized in that: It also includes an activation rod (4), which is coaxially arranged in the sleeve (2), one end of the activation rod (4) abuts against the end surface of the frustum (12) of the nail body (1), and the outer wall of the activation rod (4) at the other end is threadedly connected to the inner wall of the sleeve (2).

3. The lag screw according to claim 2, characterized in that: The activation rod (4) comprises a nut (41), and the outer wall of the activation rod (4) below the nut (41) is provided with a first threaded section (42), and the first threaded section (42) is threadedly connected to a flange (222) provided on the inner wall of the sleeve (2).

4. The lag screw according to claim 1, wherein: A limiting tube (5) is provided in one end of the sleeve (2), and the inner wall of the limiting tube (5) is provided with at least one first plane (51). A second plane (13) that fits the first plane (51) is provided on the nail body (1), and the limiting tube (5) is sleeved with the nail body (1).

5. The lag screw according to claim 1, wherein: The outer diameter of the tail ring (6) is the same as the outer diameter of the middle section (22) of the sleeve (2).

6. The lag screw according to claim 1, characterized in that: The anti-slip structure (63) is a protrusion provided with an internal thread, and the introduction portion (211) is provided with an external thread. When the tail ring (6) is connected to the distal section (21), the protrusion is introduced into the middle portion (212) through the introduction portion (211).

7. A femoral intramedullary nail, comprising a main nail (8), characterized in that: Also included is the lag screw according to any one of claims 1 to 6.

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