Locking screw for locking compression steel plate

Abstract

The utility model provides a locking screw for locking a compression steel plate, which comprises a metal screw rod and a non-metal locking screw sleeve, the metal screw rod is made of metal materials, and the non-metal locking screw sleeve is made of non-metal materials. According to the utility model, the part of the locking screw, which forms the locking thread with the locking compression steel plate, is replaced by a non-metal material, so that the contact interface between the locking compression steel plate and the locking screw is changed into a metal-non-metal contact interface from a metal-metal contact interface under the condition that the fixing strength of the screw in the bone is not reduced; dangerous factors of metal cold welding are eliminated, the phenomenon of cold pressure welding / cold welding generated between metal due to too large screwing torque or fracture micro movement is avoided, meanwhile, it is still kept that the locking and pressurizing steel plate does not make contact with the bone, the effect of an internal fixing support is achieved, and under the condition that a patient is encouraged to do early exercise after an operation, the patient can be effectively prevented from being damaged. And the screw and the steel plate can still be smoothly separated during dismounting.

Description

Technical Field

[0001] The utility model relates to the technical field of orthopedic medical instruments, in particular to a locking screw used for locking a compression steel plate. Background Art

[0002] In the field of orthopedics, for patients with long bone shaft and end fractures, the internal fixation system consisting of a locking compression plate (LCP) and a locking head screw (LHS) has become the mainstream surgical option. In the case of stable fractures, it is also convenient for patients to carry out early rehabilitation exercises. Compared with traditional conservative treatment options, it greatly reduces the occurrence of joint stiffness and muscle atrophy. Figure 1 It is a schematic diagram of the fixing principle of the locking compression plate 91 and the locking screw 92. The screw segment 921 of the locking screw 92 is connected to the bone 93. The screw cap 922 of the locking screw is also connected to the locking compression plate 91 through a tapered thread. The screw cap 922 is vertically locked to the locking compression plate 91 instead of pressing the locking compression plate 91 on the bone surface, thereby achieving the effect of an "internal fixation bracket". The gap between the locking compression plate 91 and the bone surface can retain the blood supply to the fracture end as much as possible, which is beneficial to the healing of the fracture.

[0003] The materials of locking compression plates and locking screws are generally three kinds, namely stainless steel of ISO 5832-1 standard, 4B grade pure titanium of ISO 5832-2 standard and Ti-6Al-7Nb alloy of ISO 5832-11 standard. Although these materials have good biocompatibility and compatibility with MRI and other imaging, many patients hope to be able to remove the plates in the future. The timing of plate removal often depends on a comprehensive assessment of whether the fracture site is weight-bearing, fracture healing, patient bone density and patient age. According to experience, it is generally best to remove upper limb fractures in about one year and lower limb fractures in about one and a half years. Children should be removed relatively early and the elderly should be removed relatively later. In general, the removal of plates and screws is after the affected limb is weight-bearing. According to the principles of biomechanics, the micro-motion caused by such activities will further pressurize the threads between the locking screw and the locking compression plate.

[0004] According to relevant research statistics, among patients who have locked compression plates removed, more than 10% have difficulty removing the screws, and the probability of screw slippage exceeds 17%, a large part of which is due to cold welding between the metals in the locking area of ​​the screw and the plate. Such removal difficulties will not only increase the surgical time for removal, but also cause greater secondary trauma and an increased risk of postoperative infection. Removal after screw slippage often leads to more bone destruction. Therefore, it is necessary to propose a technical solution that can effectively prevent cold welding between the screw and the locking area of ​​the plate. Summary of the Invention

[0005] To overcome the deficiencies of the above-mentioned prior art, the purpose of the present utility model is to provide a locking screw for a locking compression plate.

[0006] To achieve the above purpose, the technical solution adopted by the present utility model to solve its technical problems is: a locking screw for a locking compression plate, including a metal screw rod and a non-metal locking nail sleeve. The material of the metal screw rod is a metal material, and the material of the non-metal locking nail sleeve is a non-metal material. The metal screw rod includes a screw rod head at the top and a screw rod section below the screw rod head. An external thread is provided on the outer periphery of the screw rod section. The non-metal locking nail sleeve is fixedly connected to the screw rod head. A tapered external thread is provided on the outer periphery of the non-metal locking nail sleeve, and the outer diameter of the upper end of the non-metal locking nail sleeve is larger than the outer diameter of the lower end.

[0007] Adopting the technical solution of the present utility model, the part of the locking screw that forms a locking thread with the locking compression plate is replaced with a non-metal material. Without reducing the internal fixation strength of the screw itself in the bone mass, the contact interface between the locking compression plate and the locking screw is changed from metal-metal to metal-non-metal, eliminating the risk factor of metal cold welding and avoiding the cold pressure welding / cold welding phenomenon between metals caused by excessive screwing torque or micro-movement of the fracture. At the same time, it still maintains that the locking compression plate does not contact the bone mass, achieving the "internal fixation bracket" function, which is beneficial for the screw and the plate to be separated smoothly when removed, even when encouraging the patient to perform early exercise after the operation.

[0008] Further, the material of the non-metal locking nail sleeve is polyetheretherketone (PEEK).

[0009] Adopting the above preferred scheme, PEEK has high tensile strength and high stress cracking strength, is very outstanding in fatigue resistance under alternating stress, has a small linear expansion coefficient, good dimensional stability, and implant-grade PEEK has excellent biocompatibility and no side effects.

[0010] Further, the material of the non-metal locking nail sleeve is carbon fiber reinforced polyetheretherketone (CF-PEEK).

[0011] Adopting the above preferred scheme can significantly enhance the mechanical properties of the non-metal locking nail sleeve.

[0012] Further, the screw rod head is provided with an annular groove with a lateral opening, and the non-metal locking nail sleeve is embedded in the annular groove.

[0013] Adopting the above preferred scheme can improve the bonding strength between the non-metal locking nail sleeve and the screw rod head.

[0014] Furthermore, the outer contour of the cross-section at the root of the annular groove on the head of the screw rod is a non-circular contour, and the inner ring of the non-metallic locking sleeve is provided with a hole structure that meshes with the non-circular contour at the root of the annular groove.

[0015] Furthermore, the outer contour of the cross-section at the root of the annular groove is a star-shaped contour with multiple angular points distributed at intervals, and the inner ring of the non-metallic locking sleeve is provided with a hole structure that meshes with the star-shaped contour at the root of the annular groove.

[0016] Furthermore, the outer contour of the cross-section at the root of the annular groove is a polygonal contour, and the inner ring of the non-metallic locking sleeve is provided with a hole structure that meshes with the polygonal contour at the root of the annular groove.

[0017] Adopting the above preferred solution further enhances the ability of the non-metallic locking sleeve to withstand torsional strength.

[0018] Furthermore, the top surface of the head of the metal screw rod is provided with an inwardly concave plum blossom-shaped or polygonal groove.

[0019] Adopting the above preferred solution, the docking card slot with the locking tool is arranged at the head end of the metal screw rod to ensure stable torque transmission.

[0020] Furthermore, the material of the metal screw rod is stainless steel, 4B grade pure titanium or Ti-6Al-7Nb alloy.

[0021] Adopting the above preferred solution has good biocompatibility and compatibility with nuclear magnetic resonance and other imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is a schematic diagram of the fixing principle of a locking compression plate and a locking screw in the prior art.

[0024] Figure 2 It is a perspective view of an embodiment of the locking screw of the present invention.

[0025] Figure 3 It is a cross-sectional view of an embodiment of the locking screw of the present invention.

[0026] Figure 4 It is a perspective view of an embodiment of the metal screw rod.

[0027] Figure 5It is the front view of an embodiment of a metal screw rod.

[0028] Figure 6 It is Figure 5 the sectional view taken along the A-A direction in

[0029] Figure 7 It is the top view of an embodiment of a metal screw rod.

[0030] The names of the corresponding components indicated by the numbers and letters in the figure:

[0031] 11 - Metal screw rod; 111 - Screw rod head; 1111 - Ring groove; 1112 - Star profile; 1113 - Plum blossom groove; 112 - Screw rod section; 113 - External thread; 12 - Non-metallic locking nail sleeve; 121 - Tapered external thread; 91 - Locking compression plate; 92 - Locking screw; 921 - Screw rod section; 922 - Screw cap; 93 - Bone. Specific embodiments

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0033] As Figure 2-7 shown, in one embodiment of the present invention: A locking screw for a locking compression plate includes a metal screw rod 11 and a non-metallic locking nail sleeve 12. The material of the metal screw rod 11 is a metal material, and the material of the non-metallic locking nail sleeve 12 is a non-metallic material. The metal screw rod 11 includes a screw rod head 111 at the top and a screw rod section 112 below the screw rod head. An external thread 113 is provided on the outer periphery of the screw rod section 112. The non-metallic locking nail sleeve 12 is fixedly connected to the screw rod head 111. A tapered external thread 121 is provided on the outer periphery of the non-metallic locking nail sleeve 12, and the outer diameter of the upper end of the non-metallic locking nail sleeve 12 is greater than the outer diameter of the lower end.

[0034] The beneficial effects of adopting the above technical solution are as follows: The part of the locking screw that forms a locking thread with the locking compression plate is replaced with a non-metallic material. Without reducing the internal fixation strength of the screw itself in the bone, the contact interface between the locking compression plate and the locking screw is changed from metal-metal to metal-non-metal, eliminating the risk factor of metal cold welding and avoiding the cold pressure welding / cold welding phenomenon between metals caused by excessive screwing torque or micro-movement of the fracture. At the same time, it still maintains that the locking compression plate does not contact the bone, achieving the function of an "internal fixation bracket", which is beneficial for the screw and the plate to be separated smoothly when removed while encouraging the patient to perform early exercises after the operation.

[0035] In some other embodiments of the present invention, the non-metallic locking nail sleeve 12 is made of a non-metallic material. The specific non-metallic material is not limited and can be selected from the prior art, and a non-metallic material with high physical properties and biocompatibility is selected.

[0036] In some other embodiments of the present invention, the material of the non-metallic locking nail sleeve 12 is selected as polyetheretherketone (PEEK). The beneficial effects of adopting the above technical solution are as follows: PEEK has high tensile strength and high stress cracking strength, is very prominent in fatigue resistance under alternating stress, has a small linear expansion coefficient and good dimensional stability, and implant-grade PEEK has excellent biocompatibility and no side effects.

[0037] In some other embodiments of the present invention, in order to enhance the mechanical properties of the non-metallic locking nail sleeve 12, the material can be further upgraded to carbon fiber reinforced polyetheretherketone (CF-PEEK).

[0038] As Figure 4 shown, in some other embodiments of the present invention, the screw rod head 111 is provided with a laterally open annular groove 1111, and the non-metallic locking nail sleeve 12 is embedded in the annular groove 1111. The beneficial effects of adopting the above technical solution are as follows: It improves the bonding strength between the non-metallic locking nail sleeve and the screw rod head.

[0039] In some other embodiments of the present invention, the outer contour of the root cross-section of the annular groove 1111 of the screw rod head 111 is a non-circular contour. The non-metallic locking nail sleeve 12 is attached to the annular groove 1111 of the screw rod head 111 by injection molding, and the inner ring of the non-metallic locking nail sleeve 12 is provided with a hole body structure meshing with the non-circular contour of the annular groove root. For example, as Figure 6As shown, the outer contour of the root section of the annular groove 1111 is a star-shaped contour 1112 with 8 sharp corners, and the inner ring of the non-metallic locking nail sleeve 12 is provided with a hole structure that meshes with the star-shaped contour at the root of the annular groove. Again, the outer contour of the root section of the annular groove 1111 is a polygonal contour, and the inner ring of the non-metallic locking nail sleeve 12 is provided with a hole structure that meshes with the polygonal contour at the root of the annular groove. The beneficial effect of adopting the above technical solution is: further enhancing the ability of the non-metallic locking nail sleeve to withstand torsional strength.

[0040] As Figure 7 shown, in some other embodiments of the present invention, the top surface of the screw rod head 111 of the metal screw rod 11 is provided with an inwardly concave plum blossom-shaped or polygonal groove. In Figure 7 shown is the plum blossom-shaped groove 1113. The beneficial effect of adopting the above technical solution is: the docking card slot with the locking tool is arranged at the head end of the metal screw rod to ensure the stable transmission of torque.

[0041] In some other embodiments of the present invention, the material of the metal screw rod 11 is selected from stainless steel, 4B grade pure titanium or Ti-6Al-7Nb alloy. The beneficial effect of adopting the above technical solution is: having good biocompatibility and compatibility with nuclear magnetic resonance and other imaging.

[0042] The above embodiments are only for illustrating the technical concept and characteristics of the present invention, and their purpose is to enable those of ordinary skill in the art to understand the content of the present invention and implement it, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A locking screw for locking a pressurized steel plate, characterized in that: It comprises a metal screw rod and a non-metallic locking nail sleeve, wherein the metal screw rod is made of metal material, and the non-metallic locking nail sleeve is made of non-metallic material. The metal screw rod comprises a screw rod head at the top and a screw rod section below the screw rod head, an outer circumference of the screw section is provided with an external thread, the non-metallic locking nail sleeve is fixedly connected to the screw rod head, an outer circumference of the non-metallic locking nail sleeve is provided with a conical external thread, and the outer diameter of the upper end of the non-metallic locking nail sleeve is greater than the outer diameter of the lower end.

2. The locking screw for locking a pressurized steel plate according to claim 1, characterized in that: The material of the non-metallic locking nail sleeve is PEEK.

3. The locking screw for locking a pressurized steel plate according to claim 1, characterized in that: The material of the non-metallic locking nail sleeve is CF-PEEK.

4. The locking screw for locking a pressurized steel plate according to claim 1, characterized in that: The head of the screw rod is provided with a side-opening annular groove, and the non-metallic locking nail sleeve is embedded in the annular groove.

5. The locking screw for locking a pressurized steel plate according to claim 4, characterized in that: The outer contour of the cross section of the root of the annular groove of the screw rod head is a non-circular contour.

6. The locking screw for locking a pressurized steel plate according to claim 5, characterized in that: The outer contour of the cross section of the root of the annular groove is a star-shaped contour with a plurality of sharp corners distributed at intervals.

7. The locking screw for locking a pressurized steel plate according to claim 5, characterized in that: The outer contour of the cross section of the root of the annular groove is a polygonal contour.

8. The locking screw for locking a pressurized steel plate according to claim 1, characterized in that: The top surface of the screw rod head of the metal screw rod is provided with a concave plum blossom-shaped or polygonal groove.

9. The locking screw for locking a pressurized steel plate according to claim 1, characterized in that: The metal screw rod is made of stainless steel, 4B grade pure titanium or Ti-6Al-7Nb alloy.

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