An in vitro regulated unidirectional sliding growth rod

Abstract

This invention relates to the field of orthopedic medical device technology, specifically to an externally adjustable unidirectional sliding growth rod, comprising: a proximal sleeve, a distal sleeve, a snap-fit ​​component, a spring-driven component, and a detachable pre-bent rod. The inner wall of the distal sleeve has a linear groove, and the outer wall of the proximal sleeve forms a linear slide bar. A portion of the proximal sleeve is fitted inside the inner cylinder of the distal sleeve. The inner cylinder of the distal sleeve is equipped with the spring-driven component. The outer wall of the distal sleeve is fitted with the snap-fit ​​component. Detachable pre-bent rods are connected to both ends of the sliding growth rod. The snap-fit ​​component includes a snap-fit ​​outer shell, a limiting component, and a unidirectional sliding component. This invention can improve the performance of the growth rod.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of orthopedic medical devices, in particular to an in-vitro adjusted one-way sliding growth rod. BACKGROUND

[0002] Growth rods are orthopedic devices used to treat Early-Onset Scoliosis (EOS) in children. Since children with EOS are still in the process of bone development, traditional surgical treatments such as spinal fusion can 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, limited biocompatibility, etc. Traditional titanium alloys (such as Ti-6Al-4V) may cause potential biological toxicity due to the presence of aluminum and vanadium, and have a high elastic modulus that can lead to stress shielding effects. In addition, existing processes cannot achieve precise molding of complex internal structures (such as anti-rotation grooves).

[0003] Current growth rod designs and applications have made some progress, mainly divided into traditional growth rod systems and dynamic growth rods. Traditional growth rods (such as VEPTR system, etc.) usually use a fixed metal rod and are extended regularly through surgery, which has the advantage of providing stable correction force, but the disadvantage is that it requires multiple surgical adjustments and can cause significant burden on the spine during growth. Dynamic growth rods (such as MAGEC growth rods) achieve non-invasive extension through built-in magnetic mechanisms or mechanical devices, reducing the need for surgery, and patients can drive the extension of the growth rod through external devices during regular check-ups; however, despite the reduced need for surgery, dynamic growth rods still face technical challenges such as growth control and force adjustment.

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

[0005] In view of the above problems, the present application provides an in-vitro adjusted one-way sliding growth rod, which solves the technical problems of the prior art that the adjustment mode of the growth rod is not accurate and flexible.

[0006] The present application provides an in-vitro adjusted one-way sliding growth rod, which comprises a proximal sleeve 2, a distal sleeve 6, a buckle component 5, a spring driving component 9, a safety buckle 3 and a detachable pre-bent rod 1, a straight line sliding groove 4 is formed on the inner cylinder wall of the distal sleeve 6, a straight line sliding strip is formed on the outer wall of the proximal sleeve 2, a part of the proximal sleeve 2 is sleeved in the inner cylinder of the distal sleeve 6 and the straight line sliding strip and the straight line sliding groove 4 are matched, and the outer wall of the distal sleeve 6 is provided with the buckle component 5.

[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 that extends into the inner cylinder of the distal sleeve 6, so that the inner cylinder of the distal sleeve 6 forms a reserved space, the spring driving component 9 is arranged in the reserved space, and the two ends of the spring driving component 9 are respectively connected with the end of the inner cylinder of the distal sleeve 6 and the end of the part of the proximal sleeve 2 that extends 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 with the detachable pre-bent rod 1, and the end opposite to the end where the distal sleeve 6 and the proximal sleeve 2 are sleeved is connected with the detachable pre-bent rod 1.

[0009] Preferably, the buckle component 5 comprises a buckle shell, a limiting component 10 and a one-way sliding component 11, a buckle through hole is formed on the outer wall of the distal sleeve 6, the buckle shell 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 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 in the buckle shell 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 buckle shell, the spring is arranged perpendicularly to the outer wall of the distal sleeve 6, and the elastic force of the spring enables the limiting component 10 to rotate through the buckle through hole and fit into the limiting groove 8, so that the relative sliding of the proximal sleeve 2 and the distal sleeve 6 is limited.

[0010] Preferably, the one-way sliding component 11 is a spherical ball, a conical groove is arranged in the buckle shell, and the spherical ball is arranged in the conical groove; the conical groove is communicated with the buckle through hole, so that the spherical ball is in contact with the outer wall of the proximal sleeve 2; and along the direction in which the proximal sleeve 2 extends into the distal sleeve 6, the width of the conical groove gradually decreases, so as to limit the movement of the spherical ball along the extending direction.

[0011] Preferably, when the ball extends into the distal sleeve 6 along the proximal sleeve 2, it is pressed against the outer wall of the proximal sleeve 2, thereby restricting the sliding in the insertion direction. When the ball moves out of the distal sleeve 6 along the proximal sleeve 2, there is no pressing force between the ball and the outer wall of the proximal sleeve 2, so that the sliding in the removal direction is unrestricted.

[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 near-end sleeve 2 and the far-end sleeve 6 are specifically β-type titanium alloy sleeves, specifically made of Ti-13Nb-13Zr alloy, with a composition ratio of 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, under argon protection, 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, followed by multi-directional forging and plate rolling. Then, electron beam melting 3D printing technology is used to manufacture the straight groove 4 and limiting groove 8 structure inside the sleeve. Finally, CNC machining technology is used to precision mill the inner and outer surfaces of the sleeve with carbide tools, resulting in a β-type titanium alloy sleeve with an elastic modulus of 55 GPa.

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

[0015] Preferably, the unidirectional sliding component 11 is a zirconia ceramic ball, and the manufacturing process is as follows: using 3Y-TZP powder, a spherical preform is prepared by injection molding, then solvent degreasing and thermal degreasing are performed in sequence, followed by sintering in a hydrogen atmosphere at 1550°C for 2 hours, diamond grinding, chemical mechanical polishing, and finally argon plasma treatment to eliminate surface defects.

[0016] Preferably, the material of the spring drive component 9 is a nickel-titanium alloy with a composition ratio of 50.8% Ni and 49.2% Ti. The manufacturing process is as follows: 99.99% pure nickel and 99.99% pure titanium are vacuum induction melted and cast into ingots. Through shape memory treatment, solution treatment, and aging forming, the phase transformation temperature of the spring drive component 9 is controlled at 25-37°C, which is close to body temperature.

[0017] Preferably, the present invention provides an adjustment method for an externally regulated unidirectional sliding growth rod, comprising the following steps: during device installation, the initial position of the metal marker point is recorded using an imaging device; the growth rod is pulled using a scoliosis traction bed to adjust its length; and the difference between the current position of the metal marker point and the initial position is used to determine whether the growth rod adjustment is complete.

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

[0019] (1) This invention achieves precise corrective control through a unidirectional sliding structure combined with a spring-driven design. The unidirectional sliding mechanism between the proximal and distal sleeves allows the device to adapt to the patient's spinal growth under external traction, while the built-in spring-driven component provides a stable orthopedic force, ensuring continuous and controllable growth adjustment. In addition, the limiting component and the unidirectional sliding component in the buckle assembly enable unidirectional sliding of the sleeves, making the adjustment process both precise and safe, avoiding possible reverse displacement during sliding, and improving the corrective reliability of the device.

[0020] (2) This invention also features optimized design for long-term durability and precision maintenance, such as the introduction of limiting grooves and anti-rotation sliding groove structures, which prevent the device from rotating or loosening during adjustment. Simultaneously, the use of high-hardness, low-friction zirconia ceramic balls as unidirectional sliding components, combined with a conical groove structure, effectively reduces sliding friction, ensuring long-term stable operation of the device. Furthermore, the design of metal marker points allows doctors to visually assess the elongation of the growth rod during external adjustment, improving the accuracy of traction operations.

[0021] (3) The sleeve of the present invention is made of high-performance β-type titanium alloy material, whose low elastic modulus can effectively reduce the stress shielding effect, so that the mechanical stress is more evenly distributed on the bone tissue during the correction process, reducing the load. The phase transition temperature of the spring drive component is close to the body temperature, and the shape recovery can be triggered by the body temperature to continuously apply the corrective force without external intervention, thus improving the stability of long-term implantation. Attached Figure Description

[0022] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0023] Figure 1 A front view of the unidirectional sliding growth rod for in vitro regulation provided by the present invention.

[0024] Figure 2 A side view of the unidirectional sliding growth rod with in vitro regulation provided by the present invention.

[0025] Figure 3The diagram shows the structure of the unidirectional sliding component of the in vitro regulated unidirectional sliding growth rod limiting component provided by the present invention.

[0026] Figure 4 This is a schematic diagram of a 3D model of a unidirectional sliding growth rod for in vitro regulation provided by the present invention.

[0027] Reference numerals: 1-Removable pre-bending bar, 2-Proximal sleeve, 3-Safety buckle, 4-Straight groove, 5-Snap fastener, 6-Distant sleeve, 7-Fixing screw, 8-Limiting groove, 9-Spring drive component, 10-Limiting component, 11-One-way sliding component. Detailed Implementation

[0028] To better understand the above-described objectives, features, and advantages of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other. Furthermore, the present invention can be implemented in other ways different from those described herein; therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0029] To illustrate the effectiveness of the method proposed in this invention, the following detailed description of the above technical solution is provided through a specific embodiment, such as... Figure 1 As shown, an in vitro adjustable unidirectional sliding growth rod is disclosed, including a proximal sleeve 2, a distal sleeve 6, a snap-fit ​​component 5, a spring drive component 9, a safety buckle 3, and a detachable pre-bending rod 1. The inner wall of the distal sleeve 6 is provided with a linear groove 4, and the outer wall of the proximal sleeve 2 is formed with a linear slide bar. The linear slide bar and the linear groove 4 cooperate. A part of the proximal sleeve 2 is sleeved inside the inner wall of the distal sleeve 6, and the outer wall of the distal sleeve 6 is provided with a snap-fit ​​component 5.

[0030] The inner cylinder length of the distal sleeve 6 is greater than the length of the portion of the proximal sleeve 2 that extends into the inner cylinder of the distal sleeve 6, so that the inner cylinder of the distal sleeve 6 forms a reserved space. The spring drive component 9 is disposed in the reserved space, and the two 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 portion of the proximal sleeve 2 that extends into the inner cylinder of the distal sleeve 6.

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

[0032] This invention achieves anti-rotation sliding function by setting a linear slide groove, ensuring the device remains stable during adjustment. The spring drive component 9 provides the entire device with driving force in the direction of proximal sleeve 2 movement, which can assist in spinal growth and correction.

[0033] The latching component 5 includes a latching housing, a limiting component 10, and a one-way sliding component 11. A latching through-hole is formed on the outer wall of the distal sleeve 6. The latching housing is fixed to the outer wall of the distal sleeve 6 and covers the latching through-hole to limit the operating 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 latching housing via a rotating shaft along the tangent direction of the outer wall of the distal sleeve 6. A spring connects the limiting component 10 and the latching housing. The spring is perpendicular to the outer wall of the distal sleeve 6. The elastic force of the spring allows the limiting component 10 to rotate through the latching through-hole and fit into the limiting groove 8. This restricts the relative sliding of the proximal sleeve 2 and the distal sleeve 6, preventing slippage during the sliding process.

[0034] The one-way sliding component 11 is a sphere. A conical groove is provided inside the snap-fit ​​housing, and the sphere is positioned within this groove. The conical groove communicates with the snap-fit ​​through-hole, allowing one end of the sphere to contact the outer wall of the proximal sleeve 2. The width of the conical groove gradually decreases along the direction in which the proximal sleeve 2 extends into the distal sleeve 6, thus restricting the movement of the sphere in this direction. When the sphere extends from the proximal sleeve 2 into the distal sleeve 6, the conical groove restricts the sphere, causing one end of the sphere to press against the outer wall of the proximal sleeve 2, thereby limiting sliding in the insertion direction. When the sphere moves out of the distal sleeve 6, the conical groove's restriction on the sphere disappears, and there is no pressure between one end of the sphere and the outer wall of the proximal sleeve 2, allowing unrestricted sliding in the removal direction. Through this method, the one-way sliding function can be achieved by controlling whether the sphere presses against the proximal sleeve wall.

[0035] In some embodiments, the snap-fit ​​housing is provided with metal markers to assist in real-time monitoring of the distraction distance when adjusting the length of the growth rod. Specifically, during initial installation, the initial position of the metal markers is recorded using an imaging device for comparison during subsequent adjustments. During the traction process of adjusting the length of the growth rod, the relative position of the metal markers and the proximal sleeve 2 changes. The imaging device can capture these relative position changes at different time points. By comparing the images, the movement distance of the metal markers from their initial position can be accurately measured, thereby determining the degree of distraction.

[0036] Correspondingly, the present invention provides an adjustment method for an externally regulated unidirectional sliding growth rod, characterized by the following steps: during equipment installation, the starting position of the metal marker point is recorded using an imaging device; the growth rod is pulled using a scoliosis traction bed to adjust its length; and the difference between the current position of the metal marker point and the starting position is used to determine whether the growth rod adjustment is complete.

[0037] In some embodiments, the growth rod is dynamically adjusted using flexible braces and non-invasive distraction technology. A special scoliosis traction bed is used to precisely traction and adjust the growth rod. The traction bed is equipped with head-to-foot axial traction and a three-point force lateral 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 by fixing screws 7, which facilitates 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 that fixes the growth rod when the equipment 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 unidirectional limiting device inside the growth rod of this invention can precisely maintain the adjusted state, significantly reducing the risk of infection and improving operational safety. The new design, combining a spring-driven assembly and a non-invasive elongation mechanism, improves dynamic correction capabilities.

[0041] The growth rod of the present invention has better biocompatibility and performance advantages compared with traditional growth rods, as described in detail below.

[0042] The proximal sleeve 2 and distal sleeve 6 of this invention specifically employ β-type titanium alloy sleeves, specifically made of Ti-13Nb-13Zr alloy, with a composition of 74% Ti, 13% Nb, and 13% Zr. Its elastic modulus is 55 GPa, close to the elastic modulus of human bone (30 GPa), which significantly reduces the stress shielding effect during correction and possesses excellent corrosion resistance, showing no corrosion after >1000 hours of salt spray testing. This invention achieves unidirectional sliding with zero offset and a tolerance ≤10 μm through the establishment of a β-type titanium alloy sleeve and an anti-rotation groove structure, using geometric constraints. The low elastic modulus of the material reduces bone resorption, while the anti-rotation structure precisely transmits the corrective force, avoiding uneven stress on the spine.

[0043] The manufacturing process of the β-type titanium alloy sleeve is as follows: Vacuum arc melting (VAR) technology is used to perform three melting processes under argon protection, involving titanium with a purity of 99.99%, niobium with a purity of 99.95%, and zirconium with a purity of 99.95% to ensure uniform composition and control the composition deviation to ≤0.5%. Subsequently, thermomechanical treatment is performed, followed by multi-directional forging in the β-phase region at 900℃, with a total deformation of 70% to refine the grain to ≤50μm. The material is then rolled into sheet metal to the target thickness, such as 3mm, with the final rolling temperature controlled at 800℃. Finally, electron beam melting (EBM) 3D printing technology is used, employing a layer thickness of 50μm, an electron beam power of 3kW, a scanning speed of 7mm / s, and a vacuum degree of 10... -5 The process parameters of mbar enable precise printing and direct fabrication of structures such as the linear groove 4 and the limiting groove 8 inside the sleeve, thereby reducing subsequent machining steps. Finally, CNC machining technology is used to perform precision milling on the inner and outer surfaces of the sleeve using carbide tools. The surface roughness Ra after machining can reach ≤0.8μm, while ensuring that the inner diameter tolerance is controlled within ±0.01mm and the wall thickness tolerance is within ±0.05mm.

[0044] The surface coating of the β-type titanium alloy sleeve consists of three carbon-based materials: a bottom layer (transition layer) of amorphous carbon (aC) with a thickness of 1-2 μm, which enhances the adhesion to the titanium alloy substrate through chemical bonding; a middle layer (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; and a top layer (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 the atomic percentage, which can significantly reduce the surface energy, allowing the contact angle to reach or exceed 110°, effectively preventing tissue adhesion. The wear rate according to ASTM G99 standard does not exceed 1×10⁻⁶. -7 mm 3 / N·m; the coefficient of friction in simulated body fluid environment does not exceed 0.03.

[0045] The surface coating is manufactured as follows: the substrate is first pretreated, wherein it is roughened by sandblasting with zirconium oxide particles (50 μm in diameter) to achieve a surface roughness Ra of 3.0-4.0 μm; then, 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 on the surface (such as -OH, -COOH). The coating deposition employed plasma-enhanced chemical vapor deposition (PECVD) with the following steps: First, an amorphous carbon underlayer was deposited for 60 minutes under conditions of methane (CH) flow rate of 200 sccm, hydrogen (H) flow rate of 100 sccm, RF power of 400 W, and bias voltage of -200 V. Next, an aC:H intermediate layer was deposited for 120 minutes under conditions of acetylene (CH) flow rate of 150 sccm, hydrogen (H) flow rate of 50 sccm, and RF power of 500 W. Finally, an F-DLC surface layer was deposited for 30 minutes under conditions of carbon tetrafluoride (CF) flow rate of 100 sccm, acetylene (CH) flow rate of 50 sccm, and RF power of 300 W. After deposition, post-treatment was performed, including 30 minutes of argon plasma polishing at 200 W to reduce the surface roughness Ra to no more 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 coating stability.

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

[0047] The spring drive component is made of nickel-titanium alloy (Nitinol, Ni 50.8%, Ti 49.2%), and the manufacturing process involves: strictly controlling the synthesis ratio and heat treatment to ensure the stability of phase transformation temperature and mechanical properties. Vacuum induction melting: under high vacuum (≤10 °C) -3 In an environment of Pa, high-purity nickel (≥99.99%) and titanium (≥99.99%) are melted in proportion to avoid oxidation; electromagnetic stirring is used to ensure compositional uniformity (compositional deviation ≤ ±0.1%). Ingot casting: The molten alloy is cast into cylindrical ingots (100-300mm in diameter), and the cooling rate needs to be slow (≈10℃ / min). Shape memory treatment and solution treatment: The material is heated to 800-900℃ and held for 30min, then water quenched to obtain a uniform austenitic phase; the solution-treated material has initial shape memory characteristics. Aging forming: The material is fixed in the target shape (such as a spring or pre-bent bar), heated to 400-500℃, held for 10-60min, and then cooled; this process "memorizes" the set shape by adjusting the crystal structure, and the phase transformation temperature (Af temperature) is usually controlled at 25-37℃ (close to body temperature).

[0048] The spring-driven component of this invention, after implantation, recovers its shape through body temperature triggering, continuously applying a corrective force of, for example, 10-30N, without external intervention. At phase transition temperatures such as body temperature above 37°C, it can withstand up to 8% elastic strain (conventional metals <1%), and fully recovers after unloading. Cycle life: ≥10 cycles of hyperelasticity (conventional spring steel ≈10 cycles), suitable for long-term implantation devices.

[0049] The unidirectional sliding component of this invention uses zirconia ceramic spheres, the composition of which is ZrO2. The manufacturing process is as follows: high-purity 3Y-TZP powder, i.e., zirconia ceramic containing 3 mol% YO stabilized, is used to prepare spherical preforms by injection molding. Then, solvent degreasing and thermal degreasing are performed sequentially. Solvent degreasing involves immersion in trichloroethylene for 48 hours, while thermal degreasing is carried out in a nitrogen atmosphere at 600°C. Subsequently, sintering is performed in a hydrogen atmosphere at 1550°C for 2 hours to densify the ceramic spheres, achieving a density of not less than 6.05 g / cm³. 3 After diamond grinding, the sphericity of the ceramic spheres can be controlled to no more than 0.5 μm. Further chemical mechanical polishing reduces the surface roughness Ra to less than 0.01 μm. Finally, argon plasma treatment eliminates surface defects, achieving a hardness of over 1200 HV and a coefficient of friction not exceeding 0.1. It also possesses bioinertness and superior corrosion resistance, with an annual corrosion rate of less than 0.01 μm in bodily fluid environments, thus providing long-term stable support for unidirectional sliding components.

[0050] The unidirectional sliding component of this invention forms a "hard-hard contact" interface with the ceramic ball through a conical groove. It utilizes the elastic deformation of the ceramic (≤0.5μm) to adaptively fine-tune the sliding resistance, achieving a unidirectional sliding mechanism. The extremely high hardness of the ceramic reduces wear on the inner wall of the sleeve (90% lower wear rate compared to titanium alloy sleeves), while the stepped limiting structure prevents overshoot (adjustment accuracy ±0.1mm). The bio-inertness of zirconium oxide, combined with the sealing performance of the limiting structure, prevents metal debris from entering body fluids (metal ion release <0.1ppb).

[0051] The detachable pre-bending rod of this invention has a pre-bending angle range of 0° to 60°, is made of carbon fiber reinforced polyetheretherketone (CF / PEEK), and is fixed to the distal sleeve by titanium alloy screws with a torque range of 0.6 to 1.0 Nm. The matrix of CF / PEEK is medical-grade polyetheretherketone (PEEK). 450G), accounting for 70%, with continuous carbon fiber as the reinforcing material. The carbon fiber (T800) has a fiber diameter of 5μm, accounting for 30% of the total fiber, and adopts a unidirectional layup design. To improve the bonding strength between the fiber and the matrix, the carbon fiber surface is subjected to plasma treatment using an Ar / O2 mixed gas at a power of 200W for 5 minutes to modify the interface. The preparation process includes three steps: First, in the prepreg preparation process, the carbon fiber bundles are impregnated with molten PEEK at 380℃, cooled, and then cut into unidirectional prepreg tapes; second, in the hot pressing stage, the prepreg tapes are stacked in the 0° direction and hot-pressed at 400℃ and 10MPa pressure for 30 minutes, and then cooled and shaped; finally, in the precision machining stage, a five-axis CNC machine tool is used to process the pre-bending angle, with the angle error controlled within the range of 30° to 60° ± 0.5°, followed by surface sandblasting to achieve a surface roughness of Ra = 2-3μm. This material possesses several performance advantages. In terms of mechanical properties, its elastic modulus is 25 GPa, while that of titanium alloys is 110 GPa. This is closer to the elastic modulus of cancellous bone (0.1-2 GPa), effectively avoiding stress shielding effects. Regarding lightweighting, the material has a density of 1.5 g / cm³. 3 Compared to titanium alloy's 4.5g / cm³, 3 This reduces implant weight by up to 60%. Regarding imaging compatibility, X-ray transmittance is increased by 40%, meeting ASTM F2118 standards, thus reducing CT / MRI imaging artifacts. Furthermore, in terms of fatigue resistance, cyclic loading tests according to ISO 12106 standards show a lifespan of at least 10 cycles, superior to the 10 cycles of titanium alloys, demonstrating better long-term stability.

[0052] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

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

[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. An in-vitro regulated one-way sliding growth rod, characterized in that, The application relates to a growth rod, which comprises a proximal sleeve (2), a distal sleeve (6), a buckle component (5), a spring driving component (9), a safety buckle (3) and a detachable pre-bending rod (1), a linear sliding groove (4) is formed in the inner cylinder wall of the distal sleeve (6), a linear sliding strip is formed on the outer wall of the proximal sleeve (2), a part of the proximal sleeve (2) is sleeved in the inner cylinder of the distal sleeve (6) and the linear sliding strip and the linear sliding groove (4) are matched, and the outer wall of the distal sleeve (6) is provided with the buckle component (5). 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 the inner cylinder of the distal sleeve (6) forms a reserved space, the spring driving component (9) is arranged in the reserved space, and the two ends of the spring driving component (9) are connected with 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) respectively. The end of the proximal sleeve (2) not extending into the inner cylinder of the distal sleeve (6) is connected with the detachable pre-bending rod (1), and the end of the distal sleeve (6) opposite to the end where the proximal sleeve (2) is sleeved is connected with the detachable pre-bending rod (1). The buckle component (5) comprises a buckle shell, a limiting component (10) and a one-way sliding component (11), a buckle through hole is formed in the outer wall of the distal sleeve (6), the buckle shell is fixed on the outer wall of the distal sleeve (6) and covers the buckle through hole to limit the movement range of the limiting component (10) and the one-way sliding component (11), a limiting groove (8) is formed in the outer wall of the proximal sleeve (2), the limiting component (10) is connected in the buckle shell 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 buckle shell, the spring is arranged perpendicularly to the outer wall of the distal sleeve (6), the elastic force of the spring enables the limiting component (10) to rotate through the buckle through hole and to be embedded in the limiting groove (8) in a matched mode, so that the relative sliding of the proximal sleeve (2) and the distal sleeve (6) is limited; The one-way sliding component (11) is a spherical ball, a conical groove is arranged in the buckle shell, and the spherical ball is arranged in the conical groove; the conical groove is communicated with the buckle through hole, so that 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 conical groove gradually decreases, so as to limit the movement of the spherical ball along the extending direction; A metal mark point is arranged on the buckle shell, which is used for marking the length of extension when the length of the growth rod is adjusted. When the proximal sleeve (2) extends into the distal sleeve (6), the spherical ball is extruded with the outer wall of the proximal sleeve (2), so as to limit the sliding in the extending direction, when the proximal sleeve (2) moves out of the distal sleeve (6), the spherical ball is not extruded with the outer wall of the proximal sleeve (2), so that the sliding in the moving-out direction is not limited.

2. The in-vitro regulated one-way sliding growth rod of claim 1, wherein, ​ 3. The in-vitro regulated one-way sliding growth rod of claim 2, wherein, The proximal sleeve (2) and the distal sleeve (6) are made of a beta titanium alloy sleeve, and 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 beta titanium alloy sleeve is as follows: using vacuum arc melting technology, the titanium with a purity of 99.99%, the niobium with a purity of 99.95%, and the zirconium with a purity of 99.95% are melted for multiple times under the protection of argon, and then multi-directional forging and plate rolling are performed, and then the linear sliding groove (4) and the limiting groove (8) structure inside the sleeve are manufactured by using electron beam melting 3D printing technology, and finally, the inner and outer surfaces of the sleeve are precisely milled by using a hard alloy cutter through numerical control machining technology, so that the beta titanium alloy sleeve with an elastic modulus of 55 GPa is formed.

4. The in-vitro regulated one-way sliding growth rod of claim 3, wherein, The surface coating of the beta 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, and the surface layer is fluorinated diamond-like carbon with a thickness of 0.5-1 μm.

5. The in-vitro regulated one-way sliding growth rod of claim 4, wherein, The one-way sliding component (11) is a zirconia ceramic ball, and the manufacturing process is as follows: using 3Y-TZP powder, a spherical preform is prepared by injection molding, and then solvent debinding and thermal debinding are performed in sequence, and then sintering is performed at 1550℃ in a hydrogen atmosphere for 2 hours, and after diamond grinding, chemical mechanical polishing is performed, and finally, surface defects are eliminated through argon plasma treatment.

6. The in-vitro regulated one-way sliding growth rod of claim 5, wherein, The material of the spring driving component (9) is nickel-titanium alloy, and the component ratio is Ni 50.8% and Ti 49.2%. The manufacturing process is as follows: the pure nickel with a purity of 99.99% and the pure titanium with a purity of 99.99% are vacuum induction melted and formed into ingots, and through shape memory treatment, solid solution treatment and aging forming, the phase transition temperature of the spring driving component (9) is controlled at 25-37℃ close to body temperature.

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