One-way sliding growth rod capable of being adjusted in vitro

Abstract

The invention relates to the technical field of orthopedic medical instruments, in particular to an in-vitro adjustable one-way sliding growth rod which comprises a near-end sleeve, a far-end sleeve, a buckle component, a spring driving component and a detachable pre-bending rod, a linear sliding groove is formed in the inner sleeve wall of the far-end sleeve, and a linear sliding strip is formed on the outer wall of the near-end sleeve; one part of the near-end sleeve is sleeved with an inner cylinder of the far-end sleeve, the inner cylinder of the far-end sleeve is provided with the spring driving component, the outer wall of the far-end sleeve is provided with a buckle component, the two ends of the sliding growth rod are connected with detachable pre-bending rods respectively, and the buckle component internally comprises a buckle shell, a limiting component and a one-way sliding component; the performance of the growth rod can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of orthopedic medical devices, and particularly to a unidirectional sliding growth rod with external adjustment. Background Art

[0002] A growth rod is an orthopedic device used to treat Early-Onset Scoliosis (EOS) in children. Since the bones of children with EOS are still in the developmental process, traditional surgical treatment methods such as spinal fusion may affect the normal growth of the spine. Although existing growth rod systems (such as MAGEC, VEPTR) can reduce the number of surgeries, they still have problems such as material fatigue, insufficient adjustment accuracy, and limited biocompatibility. Traditional titanium alloys (such as Ti-6Al-4V) may cause potential biotoxicity due to the presence of aluminum and vanadium, and their high elastic modulus is likely to lead to the stress shielding effect. In addition, it is difficult to achieve precise forming of complex internal structures (such as anti-rotation chutes) with existing processes.

[0003] Some progress has been made in the design and application of current growth rods, which are mainly divided into traditional growth rod systems and dynamic growth rods. Traditional growth rods (such as the VEPTR system, etc.) usually adopt a fixed metal rod and are extended regularly through surgery. Its advantage is to provide stable correction force, but the disadvantages are that multiple surgical adjustments are required, and it may cause a large burden on the spine during the growth process. Dynamic growth rods (such as the MAGEC growth rod), on the other hand, achieve non-invasive extension through an internal magnetic mechanism or mechanical device, thus reducing the number of surgeries. Patients can drive the extension of the growth rod through an external device during regular examinations; however, although dynamic growth rods reduce the need for surgery, they still face technical challenges such as growth control and force adjustment.

[0004] Although existing growth rod systems can provide a corrective effect for EOS patients and promote the growth of the spine, they still face many challenges: Growth control problem: The growth adjustment methods of existing systems are relatively single, and it is difficult to adjust the traction force in real time according to the growth rate and spinal curvature of different patients. Long-term stability and durability: The materials and connection methods of the growth rod need to have sufficient strength and corrosion resistance to adapt to the changing needs during the growth process of children. High frequency of surgery and intervention: Although dynamic growth rods reduce the number of surgeries, regular interventions are still required to adjust the length and position of the device, which may affect the quality of life of patients. Difficulty in personalized treatment: The spinal conditions of each patient are different, and it is usually difficult for existing systems to perform precise personalized treatment, resulting in differences in treatment effects. Insufficient biocompatibility of traditional materials, and there are risks in long-term implantation. Existing processes cannot meet the high-precision manufacturing requirements of complex structures. The adjustment mechanism relies on invasive operations, and the burden on patients is large. Summary of the Invention

[0005] In view of the above problems, the present invention provides an externally adjustable unidirectional sliding growth rod, which solves the technical problems of inaccurate and inflexible adjustment methods of growth rods in the prior art.

[0006] The present invention provides an externally adjustable unidirectional sliding growth rod, including: a proximal sleeve 2, a distal sleeve 6, a snap component 5, a spring drive component 9, a safety buckle 3, and a detachable pre-bent rod 1. A linear chute 4 is provided on the inner cylindrical wall of the distal sleeve 6, and a linear slide bar is formed on the outer wall of the proximal sleeve 2. A part of the proximal sleeve 2 is sleeved inside the inner cylinder of the distal sleeve 6, and the linear slide bar and the linear chute 4 are matched. A snap component 5 is provided on the outer wall of the distal sleeve 6;

[0007] The length of the inner cylinder of the distal sleeve 6 is greater than the length of the part of the proximal sleeve 2 extending into the inner cylinder of the distal sleeve 6, so that a reserved space is formed in the inner cylinder of the distal sleeve 6. The spring drive component 9 is arranged in the reserved space, and both ends of the spring drive component 9 are respectively connected to the end of the inner cylinder of the distal sleeve 6 and the end of the part of the proximal sleeve 2 extending into the inner cylinder of the distal sleeve 6;

[0008] One end of the part of the proximal sleeve 2 that does not extend into the inner cylinder of the distal sleeve 6 is connected to the detachable pre-bent rod 1, and the detachable pre-bent rod 1 is connected to the end opposite to the end where the distal sleeve 6 and the proximal sleeve 2 are sleeved.

[0009] Preferably, the snap component 5 includes a snap housing, a limiting component 10, and a unidirectional sliding component 11. A snap through hole is provided on the outer wall of the distal sleeve 6. The snap housing is fixed on the outer wall of the distal sleeve 6 and covers the snap through hole to limit the movement range of the limiting component 10 and the unidirectional sliding component 11. A limiting groove 8 is provided on the outer wall of the proximal sleeve 2. The limiting component 10 is connected inside the snap housing through a rotating shaft. The rotating shaft is along the tangent direction of the outer wall of the distal sleeve 6. A spring is connected between the limiting component 10 and the snap housing. The spring is arranged perpendicular to the outer wall of the distal sleeve 6. The elastic force of the spring enables the limiting component 10 to rotate through the snap through hole and fit into the limiting groove 8, thereby restricting the relative sliding of the proximal sleeve 2 and the distal sleeve 6.

[0010] Preferably, the unidirectional sliding component 11 is a spherical ball. A conical groove is provided inside the snap housing. The spherical ball is arranged in the conical groove. The conical groove is communicated with the snap through hole, so that the spherical ball is in contact with the outer wall of the proximal sleeve 2. Along the direction in which the proximal sleeve 2 extends into the distal sleeve 6, the width of the conical groove gradually decreases to restrict the movement of the spherical ball along this extending direction.

[0011] Preferably, when the spherical ball extends into the distal sleeve 6 along the proximal sleeve 2, the spherical ball is squeezed against the outer wall of the proximal sleeve 2, thereby restricting the sliding in the insertion direction. When the spherical ball moves out of the distal sleeve 6 along the proximal sleeve 2, there is no squeezing force between the spherical ball and the outer wall of the proximal sleeve 2, so that the sliding in the removal direction is not restricted.

[0012] Preferably, the buckle housing is provided with metal marking points for marking the elongation length when adjusting the length of the growth rod.

[0013] Preferably, the proximal sleeve 2 and the distal sleeve 6 are specifically made of β-type titanium alloy sleeves. The specific material is Ti-13Nb-13Zr alloy, and the component ratio is Ti 74%, Nb 13%, Zr 13%. The manufacturing process of the β-type titanium alloy sleeve is as follows: Using vacuum arc melting technology, titanium with a purity of 99.99%, niobium with a purity of 99.95%, and zirconium with a purity of 99.95% are melted multiple times under argon protection, and then multi-directional forging and sheet rolling are carried out. Then, the linear chute 4 and the limiting groove 8 structures inside the sleeve are manufactured using electron beam melting 3D printing technology. Finally, using numerical control machining technology, the inner and outer surfaces of the sleeve are finely milled with cemented carbide tools. The elastic modulus of the formed β-type titanium alloy sleeve is 55 GPa.

[0014] Preferably, the surface coating of the β-type titanium alloy sleeve is composed of three layers of carbon-based materials, including: the bottom layer is amorphous carbon with a thickness of 1-2 μm, the middle layer is hydrogenated diamond-like carbon with a thickness of 3-5 μm; the surface layer is fluorinated diamond-like carbon with a thickness of 0.5-1 μm.

[0015] Preferably, the one-way sliding member 11 is a zirconia ceramic ball. The manufacturing process is as follows: 3Y-TZP powder is used to prepare a spherical preform by injection molding, and then solvent debinding and thermal debinding are carried out in sequence. Subsequently, it is sintered in a hydrogen atmosphere at 1550 °C for 2 hours. After diamond grinding, it is polished by chemical mechanical polishing, and finally, surface defects are eliminated by argon plasma treatment.

[0016] Preferably, the material of the spring drive member 9 is nickel-titanium alloy, and the component ratio is Ni 50.8%, Ti 49.2%. The manufacturing process is as follows: Nickel with a purity of 99.99% and titanium with a purity of 99.99% are melted by vacuum induction melting and ingot formed. Through shape memory treatment, solution treatment, and aging forming, the phase change temperature of the spring drive member 9 is controlled at 25-37 °C close to body temperature.

[0017] Preferably, the present invention provides a method for adjusting an externally adjustable unidirectional sliding growth rod, which includes the following steps: during equipment installation, an imaging device is used to record the starting position of the metal marking points; a scoliosis traction bed is used to traction the growth rod, adjust the length of the growth rod, and determine whether the adjustment of the growth rod is completed based on the difference between the current position and the starting position of the metal marking points.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] (1) By designing a unidirectional sliding structure combined with a spring drive design, the present invention achieves precise correction control. The unidirectional sliding mechanism between the proximal sleeve and the distal sleeve enables the device to adapt to the growth of the patient's spine under the action of external traction force. At the same time, the built-in spring drive component provides a stable orthopedic force to ensure continuous and controllable growth adjustment. In addition, the limiting component and the unidirectional sliding component in the buckle component can achieve unidirectional sliding of the sleeve, making the adjustment process both precise and safe, avoiding reverse displacement that may occur during the sliding process, and improving the correction reliability of the device.

[0020] (2) The present invention also optimizes the design for durability and precision retention during long-term use. For example, the introduction of the limiting groove and the anti-rotation chute structure avoids problems such as rotation or loosening of the device during the adjustment process. At the same time, high-hardness and low-friction zirconia ceramic balls are used as unidirectional sliding components, combined with the conical groove structure, effectively reducing sliding friction and ensuring the long-term stable operation of the device. In addition, the design of the metal marking points enables doctors to intuitively judge the elongation of the growth rod during external adjustment, improving the accuracy of traction operation.

[0021] (3) The sleeve of the present invention is made of high-performance β-type titanium alloy material, and its low elastic modulus characteristic can effectively reduce the stress shielding effect, making the mechanical stress more evenly distributed on the bone tissue during the correction process and reducing the load. The phase change temperature of the spring drive component is close to body temperature, and it can trigger shape recovery through body temperature to continuously apply a correction force without external intervention, improving the stability of long-term implantation. Description of the Drawings

[0022] The drawings are only for the purpose of showing specific embodiments and are not considered as a limitation of the present invention.

[0023] Figure 1 It is a front view structure diagram of the externally adjustable unidirectional sliding growth rod provided by the present invention.

[0024] Figure 2 It is a side view structure diagram of the externally adjustable unidirectional sliding growth rod provided by the present invention.

[0025] Figure 3Structural diagram of the one-way sliding component of the in vitro adjustable one-way sliding growth rod provided by the present invention.

[0026] Figure 4 Schematic diagram of the 3D model of the in vitro adjustable one-way sliding growth rod provided by the present invention.

[0027] Reference numerals: 1 - detachable pre-bent rod, 2 - proximal sleeve, 3 - safety buckle, 4 - linear chute, 5 - buckle component, 6 - distal sleeve, 7 - fixing screw, 8 - limiting groove, 9 - spring drive component, 10 - limiting component, 11 - one-way sliding component. Detailed implementation manners

[0028] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention will be further described in detail below with reference to the drawings and specific implementation manners. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In addition, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0029] In order to illustrate the effectiveness of the method proposed by the present invention, the above-mentioned technical solutions of the present invention will be described in detail below through a specific embodiment, as Figure 1 shown, a disclosed in vitro adjustable one-way sliding growth rod includes a proximal sleeve 2, a distal sleeve 6, a buckle component 5, a spring drive component 9, a safety buckle 3 and a detachable pre-bent rod 1. A linear chute 4 is formed on the inner cylindrical wall of the distal sleeve 6, and a linear slide bar is formed on the outer wall of the proximal sleeve 2. The linear slide bar cooperates with the linear chute 4. A part of the proximal sleeve 2 is sleeved inside the inner cylinder of the distal sleeve 6, and a buckle component 5 is provided on the outer wall of the distal sleeve 6.

[0030] The length of the inner cylinder of the distal sleeve 6 is greater than the length of the part of the proximal sleeve 2 extending into the inner cylinder of the distal sleeve 6, so that a reserved space is formed in the inner cylinder of the distal sleeve 6. The spring drive component 9 is arranged in the reserved space, and both ends of the spring drive component 9 are respectively connected to the end of the inner cylinder of the distal sleeve 6 and the end of the part of the proximal sleeve 2 extending into the inner cylinder of the distal sleeve 6.

[0031] One end of the proximal sleeve 2 that does not extend into the inner cylinder of the distal sleeve 6 is connected to the detachable pre-bent rod 1, and the detachable pre-bent rod 1 is connected to the opposite end of the end where the distal sleeve 6 and the proximal sleeve 2 are sleeved.

[0032] The present invention can achieve the anti-rotation sliding function by setting a linear chute, ensuring the stable state of the device during the adjustment process. The spring drive component 9 provides the driving force for the proximal sleeve 2 to move outwards for the whole device, and can assist in the growth and orthosis of the spine.

[0033] The snap component 5 includes a snap housing, a limiting component 10 and a one-way sliding component 11. A snap through hole is formed on the outer wall of the distal sleeve 6. The snap housing is fixed on the outer wall of the distal sleeve 6 and covers the snap through hole to define the operation range of the limiting component 10 and the one-way sliding component 11. A limiting groove 8 is formed on the outer wall of the proximal sleeve 2. The limiting component 10 is connected inside the snap housing through a rotating shaft. The rotating shaft is along the tangent direction of the outer wall of the distal sleeve 6. A spring is connected between the limiting component 10 and the snap housing. The spring is arranged perpendicular to the outer wall of the distal sleeve 6. The elastic force of the spring enables the limiting component 10 to rotate through the snap through hole and fit into the limiting groove 8, and at this time, the relative sliding between the proximal sleeve 2 and the distal sleeve 6 can be restricted. Through the above method, the situation of slipping off during the sliding process of moving out can be prevented.

[0034] The one-way sliding component 11 is a spherical ball. A tapered groove is arranged inside the snap housing. The spherical ball is arranged in the tapered groove. The tapered groove is communicated with the snap through hole, so that one end of the spherical ball is in contact with the outer wall of the proximal sleeve 2. Along the direction of the proximal sleeve 2 extending into the distal sleeve 6, the width of the tapered groove gradually decreases to restrict the movement of the spherical ball along this extending direction. When the proximal sleeve 2 extends into the distal sleeve 6, due to the restrictive effect of the tapered groove on the spherical ball, one end of the spherical ball is extruded against the outer wall of the proximal sleeve 2, thereby restricting the sliding in the extending direction. When the proximal sleeve 2 moves out of the distal sleeve 6, the restriction of the tapered groove on the spherical ball disappears, and there is no extrusion force between one end of the spherical ball and the outer wall of the proximal sleeve 2, so that the sliding in the moving out direction is not restricted. Through the above method, the one-way sliding function can be achieved by whether the spherical ball is extruded against the proximal sleeve wall.

[0035] In some embodiments, metal marking points are arranged on the snap housing, which are used to assist in real-time monitoring of the distraction distance when adjusting the length of the growth rod. Specifically, when the device is initially installed, the starting positions of the metal marking points are recorded by an imaging device for subsequent comparison during adjustment. During the traction process of adjusting the length of the growth rod, the relative positions of the metal marking points and the proximal sleeve 2 will change. The imaging device can capture the relative position changes at different time points. Through image comparison, the moving distance of the metal marking points from the starting positions can be accurately measured, so as to judge the degree of distraction.

[0036] Correspondingly, the present invention provides a method for adjusting an externally adjustable unidirectional sliding growth rod, which is characterized by including the following steps: during equipment installation, an imaging device is used to record the starting position of the metal marking points; a scoliosis traction bed is used to traction the growth rod to adjust the length of the growth rod, and it is determined whether the adjustment of the growth rod is completed based on the difference between the current position and the starting position of the metal marking points.

[0037] In some embodiments, the growth rod is dynamically adjusted through a flexible brace and a non-invasive distraction technique, and a special scoliosis traction bed is used to precisely traction and adjust the growth rod. The traction bed is equipped with head-foot axial traction and a three-point force transverse orthopedic push plate.

[0038] In some embodiments, the detachable pre-bent rod 1 is fixedly connected to the proximal sleeve 2 and the distal sleeve 6 through fixing screws 7, which is convenient for quick replacement when needed.

[0039] In some embodiments, a safety buckle 3 is connected to the outer wall of the distal sleeve 6 and the outer wall of the proximal sleeve 2. The safety buckle is a structure for fixing the growth rod when the device leaves the factory. After the growth rod is implanted, the safety buckle 3 is removed to release the thrust of the spring drive component 9.

[0040] The internal unidirectional limiting device of the growth rod of the present invention can accurately maintain the adjusted state, significantly reduce the infection risk and improve the operation safety. The new design combines a spring drive component and a non-invasive extension mechanism, improving the dynamic correction ability.

[0041] The device materials of the growth rod of the present invention have better biocompatibility and performance advantages compared with traditional growth rods, which are specifically described as follows.

[0042] The proximal sleeve 2 and the distal sleeve 6 of the present invention are specifically made of β-type titanium alloy sleeves, and the specific material is Ti-13Nb-13Zr alloy, with the composition of Ti 74%, Nb 13%, and Zr 13%. Its elastic modulus is 55 GPa, which is close to the elastic modulus of human bone, 30 GPa, and can significantly reduce the stress shielding effect during the correction process, and has excellent corrosion resistance, with no corrosion in the salt spray test for >1000 hours. The present invention establishes a β-type titanium alloy sleeve and an anti-rotation chute structure, and realizes a unidirectional sliding zero offset with a tolerance ≤10 μm through geometric constraints. The low elastic modulus of the material reduces bone resorption, and the anti-rotation structure accurately transmits the correction force to avoid uneven stress on the spine.

[0043] The manufacturing process of the β-type titanium alloy sleeve is as follows: using vacuum arc melting (VAR) technology, titanium with a purity of 99.99%, niobium with a purity of 99.95% and zirconium with a purity of 99.95% are melted three times under argon protection to ensure uniform composition and control the composition deviation to ≤0.5%. Subsequently, thermomechanical treatment is carried out, and multi-directional forging is carried out in the β phase region at 900°C, with a total deformation of 70% to refine the grains to ≤50μm. The material is then rolled into a plate to a target thickness, such as 3mm, and the final rolling temperature is controlled at 800°C. Electron beam melting (EBM) 3D printing technology is then used, with a layer thickness of 50μm, an electron beam power of 3kW, a scanning speed of 7mm / s, and a vacuum degree of 10 -5 mbar process parameters enable precise printing and direct fabrication of the sleeve's internal linear guideway 4, retaining groove 8, and other structures, thereby reducing subsequent processing steps. Finally, CNC machining technology is employed to fine-mill the sleeve's internal and external surfaces using carbide tools. The resulting surface roughness Ra can reach ≤0.8μm, while maintaining an inner diameter tolerance of ±0.01mm and a wall thickness tolerance of ±0.05mm.

[0044] The surface coating of the β-type titanium alloy sleeve is composed of three layers of carbon-based materials, including: a bottom layer (i.e., transition layer) of amorphous carbon (aC) with a thickness of 1-2 μm, which enhances the bonding strength with the titanium alloy substrate through chemical bonding; an intermediate layer (i.e., wear-resistant layer) of hydrogenated diamond-like carbon (aC:H) with a thickness of 3-5 μm and a hardness of not less than 2000 HV, providing the core wear resistance of the coating; a surface layer (i.e., anti-adhesion layer) of fluorinated diamond-like carbon (F-DLC) with a thickness of 0.5-1 μm and a surface fluorine content of not less than 20 at.%, where at.% represents atomic percentage, which can significantly reduce surface energy and make the contact angle reach or exceed 110°, effectively preventing tissue adhesion. The wear rate according to ASTM G99 standard does not exceed 1×10 -7 mm 3 / N·m; the friction coefficient in the simulated body fluid environment does not exceed 0.03.

[0045] The manufacturing process of the surface coating is as follows: The substrate is first pretreated. Among them, it is roughened by sandblasting with zirconia particles (particle size 50 μm) to make the surface roughness Ra reach 3.0 - 4.0 μm. Subsequently, it is treated in argon plasma with a power of 600 W and a pressure of 0.3 Pa for 15 minutes to generate active groups (such as -OH, -COOH) on the surface. The coating deposition uses the plasma-enhanced chemical vapor deposition (PECVD) process. The specific steps include: First, deposit an amorphous carbon bottom layer for 60 minutes under the conditions of a methane (CH) flow rate of 200 sccm, a hydrogen (H) flow rate of 100 sccm, a radio frequency power of 400 W, and a bias voltage of -200 V. Then, deposit an a-C:H intermediate layer for 120 minutes under the conditions of an acetylene (C₂H₂) flow rate of 150 sccm, a hydrogen (H) flow rate of 50 sccm, and a radio frequency power of 500 W. Finally, deposit an F-DLC surface layer for 30 minutes under the conditions of a carbon tetrafluoride (CF₄) flow rate of 100 sccm, an acetylene (C₂H₂) flow rate of 50 sccm, and a radio frequency power of 300 W. After the deposition is completed, post-treatment is also required, including polishing with argon plasma at a power of 200 W for 30 minutes to reduce the surface roughness Ra to no higher than 0.05 μm, and annealing at 250 °C for 2 hours in a vacuum environment (10⁻³ Pa) to eliminate internal stress and improve the coating stability.

[0046] The surface coating of the present invention is tightly bonded to the substrate through C-Ti chemical bonds. The high-hardness layer resists friction and wear, and the fluorine atom doping reduces the surface energy, achieving anti-adhesion, eliminating internal stress, and improving the coating stability.

[0047] The material of the spring drive component is nitinol (Ni 50.8%, Ti 49.2%). The manufacturing process is as follows: Strictly control the synthesis ratio and heat treatment to ensure the stability of the phase transition temperature and mechanical properties. Vacuum induction melting: In a high-vacuum (≤10 -3 Pa) environment, high-purity nickel (≥99.99%) and titanium (≥99.99%) are melted in proportion to avoid oxidation. Ensure the composition uniformity through electromagnetic stirring (composition deviation ≤ ±0.1%). Ingot forming: The molten alloy is cast into a cylindrical ingot (diameter 100 - 300 mm), and the cooling rate needs to be slow (≈10 °C / min). Shape memory treatment, solution treatment: The material is heated to 800 - 900 °C and held for 30 min, then water quenched to obtain a uniform austenite phase. The solution-treated material has the initial shape memory property. Ageing forming: The material is fixed in the target shape (such as a spring, pre-bent rod), heated to 400 - 500 °C, held for 10 - 60 min, and then cooled. This process "remembers" the set shape by adjusting the lattice structure, and the phase transition temperature (Af temperature) is usually controlled at 25 - 37 °C (close to body temperature).

[0048] After implantation, the spring-driven component of the present invention triggers shape recovery through body temperature, continuously applying a corrective force of, for example, 10 - 30 N without external intervention. When the phase transition temperature is above 37 °C (body temperature), it can withstand an elastic strain of up to 8% (traditional metals < 1%) and fully recovers after unloading. Cycle life: the number of superelastic cycles ≥ 10 times (traditional spring steel ≈ 10 times), suitable for long-term implant devices.

[0049] The one-way sliding component of the present invention uses zirconia ceramic balls with a composition of ZrO2. The manufacturing process is as follows: High-purity 3Y-TZP powder, that is, zirconia ceramic stabilized with 3 mol% YO, is used to prepare spherical preforms by injection molding, and then solvent debinding and thermal debinding are carried out in sequence. Solvent debinding is carried out by soaking in trichloroethylene for 48 hours, and thermal debinding is carried out in a nitrogen atmosphere at 600 °C. Subsequently, sintering is carried out in a hydrogen atmosphere at 1550 °C for 2 hours to densify the ceramic balls, achieving a density of not less than 6.05 g / cm 3 . After diamond grinding, the roundness of the ceramic balls can be controlled to not exceed 0.5 μm. Further, through chemical mechanical polishing, the surface roughness Ra is reduced to within 0.01 μm. Finally, surface defects are eliminated by argon plasma treatment, making its hardness reach above 1200 HV, the friction coefficient not exceed 0.1, and it also has biocompatibility and super corrosion resistance. The annual corrosion amount in the body fluid environment is less than 0.01 μm, thus providing long-term stable support for the one-way sliding component.

[0050] The one-way sliding component of the present invention forms a "hard-hard contact" interface with the ceramic balls through a tapered groove, and uses the elastic deformation of the ceramic (≤ 0.5 μm) to adaptively fine-tune the sliding resistance to achieve the one-way sliding mechanism. The extremely high hardness of the ceramic reduces the wear of the inner wall of the sleeve (the wear rate is reduced by 90% compared with the titanium alloy sleeve), and the stepped limit structure prevents overshoot during sliding (adjustment accuracy ± 0.1 mm). The combination of the biocompatibility of zirconia and the sealing performance of the limit structure can prevent metal debris from entering the body fluid (metal ion release amount < 0.1 ppb).

[0051] The pre-bending angle range of the detachable pre-bent rod of the present invention is 0° to 60°, and the material is carbon fiber reinforced polyetheretherketone (CF / PEEK), which is fixed to the distal sleeve by titanium alloy screws, and the torque range of the screws is 0.6 to 1.0 Nm. The matrix of CF / PEEK is medical-grade polyetheretherketone (PEEK, 450G), accounting for 70%, and the reinforcing material is continuous carbon fiber ( T800), with a fiber diameter of 5 μm and a proportion of 30%, adopts a unidirectional ply design. To improve the bonding strength between the fiber and the matrix, the carbon fiber surface is treated by plasma, using an Ar / O2 mixed gas, with a power of 200 W and a treatment time of 5 min for interface modification. The preparation process includes three steps: First, during the prepreg preparation, the carbon fiber bundle is impregnated with molten PEEK at 380 °C, and after cooling, it is cut into unidirectional prepreg tapes; Second, in the hot pressing forming stage, after the prepreg tapes are laminated in the 0° direction, they are hot pressed at 400 °C and a pressure of 10 MPa for 30 min and then cooled and shaped; Finally, in the precision machining stage, a five-axis CNC machine tool is used to machine the pre-bending angle, and the angle error is controlled within the range of 30° to 60° ± 0.5°. Subsequently, surface sandblasting treatment is carried out to make the surface roughness reach Ra = 2 - 3 μm. This material has many performance advantages. In terms of mechanical matching, the elastic modulus is 25 GPa, while that of titanium alloy is 110 GPa. In comparison, it is closer to the elastic modulus of cancellous bone (0.1 - 2 GPa), which can effectively avoid the stress shielding effect. In terms of lightweight, the material density is 1.5 g / cm 3 , compared with 4.5 g / cm 3 of titanium alloy, the weight of the implant can be reduced by up to 60%. In terms of imaging compatibility, the X-ray transmittance is increased by 40%, meeting the ASTM F2118 standard, which reduces CT / MRI imaging artifacts. In addition, in terms of fatigue resistance, according to the ISO 12106 standard for cyclic load testing, its life can reach at least 10 times, which is better than that of titanium alloy at 10 times, and has better long-term stability.

[0052] In the present invention, unless otherwise clearly defined and limited, terms such as "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through other features between them. Moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature is at a higher horizontal height than the second feature. The first feature being "below", "under" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature is at a lower horizontal height than the second feature.

[0054] In the present invention, the terms "first", "second", "third", and "fourth" are only used for descriptive purposes and should not be construed as indicating or implying relative importance. The term "plural" means two or more, unless otherwise clearly defined.

[0055] As described above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An externally adjustable unidirectional sliding growth rod, characterized in that, Comprising: A proximal sleeve (2), a distal sleeve (6), a buckle member (5), a spring drive member (9), a safety buckle (3), and a detachable pre-bent rod (1). A linear chute (4) is provided on the inner cylindrical wall of the distal sleeve (6), and a linear slide bar is formed on the outer wall of the proximal sleeve (2). A part of the proximal sleeve (2) is sleeved inside the inner cylinder of the distal sleeve (6) so that the linear slide bar and the linear chute (4) cooperate, and the buckle member (5) is provided on the outer wall of the distal sleeve (6). The length of the inner cylinder of the distal sleeve (6) is greater than the length of the part of the proximal sleeve (2) extending into the inner cylinder of the distal sleeve (6), so that a reserved space is formed in the inner cylinder of the distal sleeve (6). The spring drive member (9) is arranged in the reserved space, and both ends of the spring drive member (9) are respectively connected to the end of the inner cylinder of the distal sleeve (6) and the end of the part of the proximal sleeve (2) extending into the inner cylinder of the distal sleeve (6). One end of the proximal sleeve (2) that does not extend into the inner cylinder of the distal sleeve (6) is connected with the detachable pre-bent rod (1), and the detachable pre-bent rod (1) is connected to the opposite end of the end where the distal sleeve (6) and the proximal sleeve (2) are sleeved together.

2. The unidirectional sliding growth rod with in vitro regulation according to claim 1, characterized in that, The buckle member (5) includes a buckle housing, a limiting member (10), and a one-way sliding member (11). A buckle through-hole is provided on the outer wall of the distal sleeve (6). The buckle housing is fixed on the outer wall of the distal sleeve (6) and covers the buckle through-hole to define the movement range of the limiting member (10) and the one-way sliding member (11). A limiting groove (8) is provided on the outer wall of the proximal sleeve (2). The limiting member (10) is connected inside the buckle housing through a rotating shaft. The rotating shaft is along the tangent direction of the outer wall of the distal sleeve (6). A spring is connected between the limiting member (10) and the buckle housing. The spring is arranged perpendicular to the outer wall of the distal sleeve (6). The elastic force of the spring enables the limiting member (10) to rotate through the buckle through-hole and fit into the limiting groove (8), thereby restricting the relative sliding of the proximal sleeve (2) and the distal sleeve (6).

3. The one-way sliding growth rod with in vitro adjustment according to claim 2, wherein The one-way sliding member (11) is a spherical ball. A tapered groove is provided inside the buckle housing. The spherical ball is arranged in the tapered groove. The tapered groove communicates with the buckle through-hole, so that the spherical ball contacts the outer wall of the proximal sleeve (2). Along the direction in which the proximal sleeve (2) extends into the distal sleeve (6), the width of the tapered groove gradually decreases to restrict the movement of the spherical ball along this extending direction.

4. The unidirectional sliding growth rod with in vitro regulation according to claim 3, characterized in that When the proximal sleeve (2) extends into the distal sleeve (6), the spherical ball is extruded by the outer wall of the proximal sleeve (2), thereby restricting the sliding in the extending direction. When the proximal sleeve (2) is removed from the distal sleeve (6), there is no extrusion force between the spherical ball and the outer wall of the proximal sleeve (2), so that the sliding in the removal direction is not restricted.

5. The one-way sliding growth rod with in vitro regulation according to claim 4, wherein, A metal marking point is provided on the buckle housing for marking the elongation length when adjusting the length of the growth rod.

6. The externally adjustable unidirectional sliding growth rod according to claim 5, characterized in that, The proximal sleeve (2) and the distal sleeve (6) are specifically made of β-type titanium alloy sleeves. The specific material is Ti-13Nb-13Zr alloy, and the component ratio is Ti 74%, Nb 13%, and Zr 13%. The manufacturing process of the β-type titanium alloy sleeve is as follows: Using vacuum arc melting technology, titanium with a purity of 99.99%, niobium with a purity of 99.95%, and zirconium with a purity of 99.95% are melted multiple times under argon protection, and then multi-directional forging and sheet rolling are carried out. Then, an electron beam melting 3D printing technology is used to manufacture the linear chute (4) and the limiting groove (8) structures inside the sleeve. Finally, a numerical control machining technology is adopted, and a cemented carbide tool is used to finish milling the inner and outer surfaces of the sleeve. The elastic modulus of the formed β-type titanium alloy sleeve is 55 GPa.

7. The externally adjustable unidirectional sliding growth rod according to claim 6, wherein, The surface coating of the β-type titanium alloy sleeve consists of three layers of carbon-based materials, including: the bottom layer is amorphous carbon with a thickness of 1-2 μm, the middle layer is hydrogenated diamond-like carbon with a thickness of 3-5 μm; the surface layer is fluorinated diamond-like carbon with a thickness of 0.5-1 μm.

8. The externally adjustable unidirectional sliding growth rod according to claim 7, characterized in that, The one-way sliding component (11) is a zirconia ceramic ball. The manufacturing process is as follows: 3Y-TZP powder is used to prepare a spherical preform by injection molding, and then solvent degreasing and thermal degreasing are carried out in sequence. Subsequently, it is sintered in a hydrogen atmosphere at 1550 °C for 2 hours. After diamond grinding, it is polished by chemical mechanical polishing, and finally, surface defects are eliminated by argon plasma treatment.

9. The externally adjustable unidirectional sliding growth rod according to claim 8, characterized in that, The material of the spring drive component (9) is nickel-titanium alloy, and the component ratio is Ni 50.8%, Ti 49.2%. The manufacturing process is as follows: Nickel with a purity of 99.99% and titanium with a purity of 99.99% are subjected to vacuum induction melting and ingot forming. Through shape memory treatment, solution treatment, and aging forming, the phase transition temperature of the spring drive component (9) is controlled at 25-37 °C close to body temperature.

10. The method for adjusting an externally adjusted unidirectional sliding growth rod according to any one of claims 1-9, characterized in that Including the following steps: During equipment installation, an imaging device is used to record the starting position of the metal marking points; the growth rod is tractioned by a scoliosis traction bed, the length of the growth rod is adjusted, and it is determined whether the adjustment of the growth rod is completed based on the difference between the current position of the metal marking points and the starting position.

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