Femoral neck dynamic triangular support system

Abstract

The present invention discloses a dynamic triangular support system for the femoral neck, belonging to the technical field of orthopedic implants. The system comprises a transverse tension screw, an oblique tension screw, and an external fixation plate for attachment to the outer side of the upper end of the femur. The upper and lower portions of the external fixation plate are respectively provided with a first nail hole for accommodating the transverse tension screw and a second nail hole for accommodating the oblique tension screw. In the present invention, the external fixation plate is relatively compact and can be minimally invasively implanted without opening the medullary cavity. The external fixation plate, oblique tension screw, and transverse tension screw can be combined to form a stable triangular support system with excellent anti-rotation effect.

Description

Technical Field

[0001] The present invention relates to the technical field of orthopedic implants, in particular to a dynamic triangular support system for the femoral neck. Background Art

[0002] Triangular support intramedullary nail system (such as Figure 1 ) and femoral neck dynamic anti-rotation systems (such as Figure 2 ) is the main method for treating proximal femoral fractures.

[0003] The triangular support intramedullary nail system includes a main nail for implantation into the femoral medullary cavity, an oblique tension screw passing through the upper part of the main nail, and a transverse tension screw passing through the top of the main nail and the oblique tension screw. Its advantages are stable fixation, the fulcrum is located at the intersection to shorten the lever arm, and the triangular area formed by the interlocking screws can prevent relative rotation between the broken femoral head and the femoral shaft. Its disadvantage is that the medullary cavity needs to be opened to implant the intramedullary nail, which causes serious damage to the surrounding soft tissue and the inside of the femur. When the pressure on the femoral head is too great, the transverse tension screw is accompanied by the oblique tension screw being withdrawn to the lower left, and the transverse tension screw is easily broken due to the full pressure.

[0004] The femoral neck dynamic anti-rotation system includes a dynamic rod and an anti-retraction screw. It is relatively small and can be minimally invasively implanted without opening the medullary cavity, causing minimal damage to the surrounding soft tissue and bone. However, due to the close distance between the dynamic rod and the anti-retraction screw, the triangular area formed is small, resulting in poor anti-rotation effect. In addition, the anti-retraction screw is completely fixed on the dynamic rod and cannot disperse stress, which can easily cause the dynamic rod to break due to stress concentration after surgery. The distal end of the femoral neck dynamic anti-rotation system uses a transverse fixation screw. Since it does not intersect with the fracture line, it can only assist in stabilizing the external fixation plate and has no actual fixation effect on the fracture line. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a femoral neck dynamic triangular support system which can be minimally invasively implanted and has a good anti-rotation effect.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A dynamic triangular support system for the femoral neck includes a transverse tension screw and an oblique tension screw, and also includes an external fixation plate for being attached to the outer side of the upper end of the femur. The upper and lower parts of the external fixation plate are respectively provided with a first nail hole for accommodating the transverse tension screw and a second nail hole for accommodating the oblique tension screw.

[0008] Furthermore, the first nail hole is provided with an internal thread, and the tail end of the transverse tension screw is provided with an external thread matching the internal thread.

[0009] Furthermore, a hollow positioning cylinder is provided on the inner side of the outer fixing plate, which is connected to the second nail hole and allows the oblique tension screw to pass through.

[0010] Furthermore, an annular boss is provided at the tail of the oblique tension screw, and an annular stop matched with the annular boss is provided on the inner side of the end of the hollow positioning cylinder.

[0011] Furthermore, the rod portion of the transverse tension screw includes a first rod portion located at the tail portion and a second rod portion located at the head portion, and the diameter of the first rod portion is greater than the diameter of the second rod portion.

[0012] Furthermore, the junction of the first rod portion and the second rod portion is a transition slope, and the oblique tension screw is provided with a platform and a nail hole, the nail hole is used to accommodate the transverse tension screw, and the platform is located on the side of the nail hole close to the external fixation plate.

[0013] Furthermore, the depth of the platform does not exceed the lowest point of the upper edge of the nail hole on the oblique tension screw for accommodating the transverse tension screw.

[0014] Furthermore, the nail hole on the oblique tension screw for accommodating the transverse tension screw includes at least two holes, and the at least two holes are arranged axially along the oblique tension screw and intersecting, and a protrusion is formed at the intersection position. The at least two holes are clearance-fitted with the transverse tension screw, and the protrusion is interference-fitted with the transverse tension screw.

[0015] Furthermore, the ratio of the lengths of the first rod portion to the second rod portion is 1:1 to 2:1, and / or the ratio of the diameters of the first rod portion to the second rod portion is 4:1 to 4:3.

[0016] Furthermore, the interference of the protrusion is 0.1 mm to 1 mm, and / or the nail hole on the oblique tension screw for accommodating the transverse tension screw is three holes arranged in an intersecting manner.

[0017] The present invention has the following beneficial effects:

[0018] The dynamic triangular support system for the femoral neck of the present invention includes an external fixation plate, a transverse tension screw, and an oblique tension screw for being attached to the outer side of the upper end of the femur. The external fixation plate is relatively small and can be implanted minimally invasively without opening the medullary cavity. The external fixation plate, the oblique tension screw, and the transverse tension screw can be combined into a stable triangular support system with a good anti-rotation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural diagram of a triangular support intramedullary nail system in the prior art;

[0020] Figure 2 It is a schematic structural diagram of a femoral neck dynamic anti-rotation system in the prior art;

[0021] Figure 3It is a structural schematic diagram of an embodiment of the dynamic triangular support system for the femoral neck of the present invention;

[0022] Figure 4 for Figure 3 Stereoscopic view of the mid-angle lag screw;

[0023] Figure 5 Schematic diagram of the coordination between the transition slope of the transverse tension screw and the platform of the oblique tension screw in the present invention, wherein (a) is an overall structural diagram and (b) is a partial enlarged diagram;

[0024] Figure 6 Schematic diagrams of the cooperation between the second rod portion of the transverse tension screw and the nail hole of the oblique tension screw in the present invention, wherein (a) is an overall structural diagram, and (b) is a view of the oblique tension screw from the A direction and also shows an enlarged view of the nail hole;

[0025] Figure 7 Schematic diagram of the femoral neck dynamic triangular support system of the present invention;

[0026] Figure 8 Schematic diagram of the structure of another embodiment of the dynamic triangular support system for the femoral neck of the present invention. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0028] The present invention provides a dynamic triangular support system for the femoral neck, such as Figure 3-8 As shown, it includes a transverse tension screw 1 and an oblique tension screw 2, and also includes an external fixation plate 3 for being attached to the outer side of the upper end of the femur (away from the side of the femoral head, including the intertrochanteric crest and the surrounding area), and the upper and lower parts of the external fixation plate 3 are respectively provided with a first nail hole 31 for accommodating the transverse tension screw 1 and a second nail hole 32 for accommodating the oblique tension screw 2.

[0029] When in use, first use a tool to hold the external fixation plate 3 and place it on the outer side of the upper end of the femur, then pass the oblique tension screw 2 through the second nail hole 32 on the external fixation plate 3 for accommodating the oblique tension screw 2, and then pass the transverse tension screw 1 through the first nail hole 31 on the external fixation plate 3 for accommodating the transverse tension screw 1 and the nail hole 22 on the oblique tension screw 2 for accommodating the transverse tension screw 1.

[0030] The dynamic triangular support system for the femoral neck of the present invention includes an external fixation plate, a transverse tension screw, and an oblique tension screw for being attached to the outer side of the upper end of the femur. The external fixation plate is relatively small and can be implanted minimally invasively without opening the medullary cavity. The external fixation plate, the oblique tension screw, and the transverse tension screw can be combined into a stable triangular support system with a good anti-rotation effect.

[0031] The fixation between the transverse tension screw 1 and the external fixation plate 3 can be carried out in various conventional ways in the art. However, in order to improve the firmness of the system, it is preferred that Figure 3 As shown, the first nail hole 31 of the external fixing plate 3 is provided with an internal thread, and the tail end of the transverse tension screw 1 is provided with an external thread matching the internal thread, so that the transverse tension screw 1 can be locked together with the external fixing plate 3 to improve the overall firmness.

[0032] The fixation between the oblique tension screw 2 and the external fixation plate 3 can also be carried out in various conventional ways in the art. However, in order to improve the firmness of the system, it is preferred that Figure 3 and Figure 8 As shown, the inner side of the external fixation plate 3 is provided with a hollow positioning tube 33 that is connected to the second nail hole 32 and through which the oblique tension screw 2 passes. This has the following advantages: first, it can improve the fixation strength between the external fixation plate 3 and the bone; second, it can prevent the tail end of the oblique tension screw 2 from protruding from the bone surface; third, it can also improve the fixation strength between the oblique tension screw 2 and the external fixation plate 3; fourth, it can restrain the oblique tension screw 2 to a certain extent, effectively reducing the shaking of the oblique tension screw 2; and fifth, it plays a certain guiding role during the implantation of the oblique tension screw 2, making the implantation direction more precise. Furthermore, to facilitate the connection and fixation of the oblique tension screw 2 and the hollow positioning tube 33, an annular boss 21 is provided at the tail end of the oblique tension screw 2, and an annular stop 331 is provided on the inner side of the end of the hollow positioning tube 33 to cooperate with the annular boss 21. By setting the annular boss 21 and the annular stop 331, the implantation depth of the oblique screw can be effectively controlled.

[0033] The inventors found during the research that Figure 7 As shown, after the product of the present invention is implanted in the human body, when the oblique nail is withdrawn due to the collapse of the fracture line M, the pressure transmitted by the femoral head will be pressed on the transverse nail. The pressure F exerted on the triangular support system of the femoral neck presses the femoral head downward, and the transverse nail and the oblique nail share the force F. When the oblique nail is withdrawn to the lower left due to excessive bearing force, the oblique nail presses the pressure on the transverse nail. The stress concentration points where the transverse nail bears the pressure are respectively the fulcrum Q at the position of the nail hole intersecting with the oblique nail and the fulcrum W at the position connected to the hole of the fixing plate. The lever arm L1 of the fulcrum Q is smaller than the lever arm L2 of the fulcrum W. The torque M=FL. When the pressure is the same, the torque of the fulcrum Q is smaller than the torque of the fulcrum W. Therefore, the closer the screw is to the external fixation plate, the greater the torque it bears and the easier it is to break.

[0034] In the present invention, Figure 3-8As shown, the transverse tension screw 1 can be designed with different diameters (variable diameter structure), that is, it includes a first rod portion 11 located at the tail (left end in the figure) and a second rod portion 12 located at the head (right end in the figure). The diameter D of the first rod portion 11 is larger than the diameter d of the second rod portion 12. Since the stress concentration of this product is mainly on the transverse tension screw 1, the diameter D of the first rod portion 11 is relatively thick, which can prevent the transverse tension screw 1 from breaking during use; the second rod portion 12 cooperates with the nail hole 22 of the oblique tension screw 2. The diameter d of the second rod portion 12 is relatively thin, which can reduce the diameter of the nail hole 22 that cooperates with it, and prevent the oblique tension screw 2 from breaking due to the position of the nail hole 22 being too thin. Therefore, the present invention can better prevent the transverse tension screw 1 and the oblique tension screw 2 from breaking. The present invention increases the diameter D of the transverse nail close to the external fixation plate without changing the diameter of the oblique nail hole, which can make the transverse nail stronger and less likely to break.

[0035] To increase the strength of the transverse tension screw 1 at the location where the diameter changes, the junction of the first rod 11 and the second rod 12 can be a transition bevel 13. Furthermore, when in use, the transition bevel 13 can be located at the nail hole 22 on the oblique tension screw 2 for accommodating the transverse tension screw 1. The oblique tension screw 2 can be provided with a platform 24 that cooperates with the transition bevel 13. The platform 24 can be located on the side of the nail hole 22 near the external fixation plate 3. The platform 24 can be formed by milling. After the first rod 11 is thickened, the weak point of the transverse tension screw 1 is located at the junction of the first rod 11 and the second rod 12. Pressure acts on the right end of the transverse tension screw 1. Therefore, by extending the length of the first rod 11 as much as possible, the force arm at the junction of the first rod 11 and the second rod 12 can be shortened, making the transverse tension screw 1 stronger and effectively preventing the transverse tension screw 1 from breaking. Since the device acts on the human body, due to the particularity of the application subject, the specifications and size need to be strictly controlled, and any changes in any place may have a huge impact. The setting of the platform 24 provides a certain avoidance space for the first rod 11, which can maximize the length of the first rod 11 within the limited nail placement space. It can not only effectively and appropriately extend the length of the first rod 11 and increase the pressure resistance of the transverse tension screw 1, but also will not cause changes in the size of the transverse tension screw 1 or even the entire system, thereby increasing the pressure resistance of the transverse tension screw 1 without affecting other performances of the entire product.

[0036] Specifically, if Figure 5 As shown in Figure (b), the transition bevel 13 of the cross nail shank is located near the left side of the cross nail, as shown by the dotted line in the figure, before the diagonal nail hole 22 is flattened. After the diagonal nail hole 22 is flattened, the transition bevel 13 of the cross nail shank can be extended to the right. The cross nail is prone to breaking at this location during use. Moving this location to the right can reduce the torque acting on this location and lower the risk of cross nail breakage.

[0037] It is understandable that, according to actual needs, the platform 24 and the transition slope 13 may not directly contact each other in the initial installation stage. A certain gap may be left between the two, or they may just overlap each other. During the later activities, the platform 24 will not cause too much reverse force on the transition slope 13, thereby preventing the lateral tension screw 3 from retreating.

[0038] The depth of the platform 24 is preferably not more than the lowest point of the upper edge of the nail hole 22 on the oblique tension screw 2 for accommodating the transverse tension screw 1. This will not weaken the position strength of the nail hole 22 of the oblique tension screw 2. At the same time, the length of the first rod 11 that cooperates with it can be extended as much as possible to make the transverse tension screw 1 stronger.

[0039] Optionally, the inclination angle of the transition slope 13 can be 30-60 degrees, specifically 30, 45, or 60 degrees. Within this range, the contact between the transition slope 13 and the platform 24 is more complete, resulting in a relatively larger contact area. This can appropriately increase the support provided by the oblique tension screw 2 on the transverse tension screw 1, thereby enhancing the overall system's compressive strength.

[0040] Taking into account the required strength of the transverse tension screw 1 and the space available for screw placement in the femur, the length ratio of the first shaft 11 to the second shaft 12 is preferably between 1:1 and 2:1, and the diameter ratio of the first shaft 11 to the second shaft 12 is preferably between 4:1 and 4:3. By limiting the length and diameter of the first and second shafts 11, 12, the strength of the transverse tension screw 1 can be fully maintained within the limited screw placement space. In practical applications, different ratio ranges can be selected based on the desired specifications. For example, the length ratio of the first and second shafts 11, 12 can be 1:1, 1.5:1, 2:1, etc., and the diameter ratio can be 4:1, 2:1, 4:3, etc.

[0041] The first rod portion 11 and the second rod portion 12 may be integral or detachably connected.

[0042] Furthermore, the nail hole 22 on the oblique tension screw 2 for accommodating the transverse tension screw 1 may include at least two holes, and the at least two holes are arranged axially along the oblique tension screw 2 and intersecting, and a protrusion 23 is formed at the intersection position. The at least two holes are clearance-matched with the transverse tension screw 1, and the protrusion 23 is interference-fitted with the transverse tension screw 1. In this way, the nail hole 22 is clearance-matched with the transverse tension screw 1 to ensure that the transverse tension screw 1 can pass through the nail hole 22; the protrusion 23 is interference-fitted with the transverse tension screw 1, so that the transverse tension screw 1 can support the oblique tension screw 2 and bear a certain pressure transmitted downward by the oblique tension screw 2. At the same time, the interference fit of the protrusion 23 with the transverse tension screw 1 can also effectively slow down the nail withdrawal phenomenon caused by the oblique tension screw 2 after surgery; when the pressure of the oblique tension screw 2 on the transverse tension screw 1 is too large, the transverse tension screw 1 slides over the protrusion 23 in the oblique tension screw 2 groove (i.e., the nail hole 22) and transitions from one hole to another, exchanging position transition for pressure reduction, reducing the borne pressure, and better preventing the transverse nail from breaking, while achieving dynamic support.

[0043] Taking into account factors such as force, the interference fit of protrusion 23 is preferably 0.1 to 1 mm, which can be adjusted based on the diameter of the screw and the amount of pressure transmitted by the femoral head. In the embodiment shown in the figure, the screw holes 22 on the oblique tension screw 2 for accommodating the transverse tension screw 1 are three intersecting holes. It should be understood that the implementer can adjust the number of intersecting holes as needed, increasing or decreasing them as appropriate, as long as the technical problem to be solved by the embodiment of the present invention is achieved.

[0044] exist Figure 8 In the illustrated embodiment, in order to ensure that the lower end of the external fixation plate 3 is in close contact with the side wall of the femur and prevent it from tilting up due to the withdrawal of the oblique tension screw 2 after surgery, a third nail hole 34 can be provided on the external fixation plate 3 below the second nail hole 32, and a distal transverse fixation screw 4 is provided in the third nail hole 34.

[0045] In summary, the present invention combines the advantages of the existing triangular support intramedullary nail system and the femoral neck dynamic anti-rotation system and optimizes the design. Specifically, based on the external fixation method of the femoral neck dynamic anti-rotation system, the power rod and the anti-retraction screw are combined into an oblique tension screw, and a slot is opened on the rod portion thereof. The upper end of the external fixation plate is extended and a first nail hole is added thereon. The distal transverse tension screw is moved to the proximal end, and the tip of the transverse tension screw passes through the nail hole of the oblique tension screw rod to fix the femoral head. The tail end of the transverse tension screw is threaded and cooperates with the internal thread of the first nail hole of the external fixation plate, thereby locking the transverse tension screw and the external fixation plate into one, forming a stable triangular support system composed of the external fixation plate, the oblique tension screw and the transverse tension screw, namely the femoral neck triangular support system.

[0046] The present invention combines the external fixation and minimally invasive features of the triangular support intramedullary nail system with the femoral neck dynamic anti-rotation system to design a triangular support system for the femoral neck. This system mainly consists of an external fixation plate, an oblique tension screw, a transverse tension screw, etc., forming a stable triangular support system, wherein the external fixation plate is the main connecting structure, the oblique tension screw passes through the second nail hole of the external fixation plate, the fracture line, etc., to connect the femoral head and the femoral shaft as one, and the tip of the transverse tension screw passes through the external fixation plate, the fracture line, and the nail hole of the oblique tension screw to connect the femoral head and the femoral shaft as one, and the transverse tension screw is locked to the external fixation plate through the external thread at the tail end. The oblique tension screw is non-lockingly connected to the external fixation plate, and has two or more continuous nail holes. There are protrusions between adjacent nail holes, and the spacing between the protrusions is smaller than the diameter of the second rod of the transverse tension screw through the nail hole position. The transverse tension screw can support the protrusions of the nail holes under a certain pressure to stabilize the oblique tension screw. However, when the pressure is too large, the rod of the transverse tension screw will pass through the protrusion on one nail hole and enter the next nail hole (at this time, the fracture line collapses, increasing the bone density at the fracture line position and improving the supporting force between bones). By changing position, the pressure is reduced, the load-bearing pressure is reduced, and the transverse tension screw is prevented from breaking.

[0047] Transverse tension screws are available in different diameters. The diameter D of the first rod is larger than the diameter d of the second rod. The first and second rods are connected by a transition surface. When the femoral head applies pressure to the right side of the transverse tension screw, the left side bears a greater torque due to the longer lever arm, making it easier to break at the same diameter. The screw hole on the oblique tension screw is milled flat, and the milling position does not exceed the lowest point of the screw hole edge, which will not affect the strength of the oblique tension screw (the lowest point of the screw hole is the thinnest, such as Figure 4 Flattening the hole (as shown in B in the figure) shifts the transition surface of the transverse tension screw to the right, increasing the length of the first shank. Increasing the diameter D and length of the first shank enhances the strength of the transverse tension screw without increasing its diameter.

[0048] The distal transverse fixation screw of the original femoral neck dynamic anti-rotation system can be removed ( Figure 3 ), or you can keep ( Figure 8 ), in the femoral neck triangular support system, the triangular support alone can stabilize the femoral neck fracture. Retaining the distal transverse fixation screw can make the lower end of the external fixation plate fit closely with the femoral side wall, preventing it from tilting up due to the withdrawal of the oblique tension screw after surgery.

[0049] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A dynamic triangular support system for the femoral neck, comprising a transverse tension screw and an oblique tension screw, characterized in that: It also includes an external fixation plate for being attached to the outside of the upper end of the femur, wherein the upper and lower parts of the external fixation plate are respectively provided with a first nail hole for accommodating the transverse tension screw and a second nail hole for accommodating the oblique tension screw; The rod portion of the transverse tension screw includes a first rod portion located at the tail portion and a second rod portion located at the head portion, the diameter of the first rod portion is greater than the diameter of the second rod portion, and the length ratio of the first rod portion to the second rod portion is 1:1 to 2:1; The junction of the first rod portion and the second rod portion is a transition inclined surface. The oblique tension screw is provided with a nail hole and a platform matching the transition inclined surface. The nail hole is used to accommodate the transverse tension screw. When in use, the transition inclined surface is located at the nail hole, and the platform is located on the side of the nail hole close to the external fixation plate.

2. The dynamic triangular support system for the femoral neck according to claim 1, characterized in that: The first nail hole is provided with an internal thread, and the tail end of the transverse tension screw is provided with an external thread matching the internal thread.

3. The dynamic triangular support system for the femoral neck according to claim 1, characterized in that: A hollow positioning cylinder is provided on the inner side of the outer fixing plate, which is connected with the second nail hole and is used for the oblique tension screw to pass through.

4. The dynamic triangular support system for the femoral neck according to claim 3, characterized in that: An annular boss is provided at the tail of the oblique tension screw, and an annular stop matched with the annular boss is provided on the inner side of the end of the hollow positioning cylinder.

5. The dynamic triangular support system for the femoral neck according to claim 1, characterized in that: The depth of the platform does not exceed the lowest point of the upper edge of the nail hole on the oblique tension screw for accommodating the transverse tension screw.

6. The dynamic triangular support system for the femoral neck according to claim 1, characterized in that: The ratio of the diameters of the first rod portion to the second rod portion is 4:1 to 4:

3.

7. The dynamic triangular support system for the femoral neck according to any one of claims 1 to 4, characterized in that: The nail hole on the oblique tension screw for accommodating the transverse tension screw includes at least two holes, and the at least two holes are arranged axially along the oblique tension screw and intersecting, with a protrusion formed at the intersection position. The at least two holes are clearance-fitted with the transverse tension screw, and the protrusion is interference-fitted with the transverse tension screw.

8. The dynamic triangular support system for the femoral neck according to claim 7, characterized in that: The interference fit of the protrusion is 0.1 mm to 1 mm, and / or the nail holes on the oblique tension screw for accommodating the transverse tension screw are three holes arranged in an intersecting manner.

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