A connecting rod fixation device for thoracolumbar fracture and a preparation method thereof

Abstract

The application discloses a connecting rod fixing device for thoracolumbar fracture and a preparation method thereof, which comprises a connecting piece in the shape of a rod and made of titanium alloy, at least one end of the connecting piece is connected with a porous structure piece, the porous structure piece is made of self-dissolving material, the porous structure piece is provided with a three-dimensional communicating porous structure, the three-dimensional communicating porous structure is filled with cross-linked hydrogel, the connecting piece is arranged at a fused segment, and the porous structure piece is arranged at a non-fused segment. The porous structure piece at the non-fused segment can be selectively self-dissolved, so that the spinal motion function is restored, the increase of stress of adjacent segments and the occurrence of degeneration caused by long segment fixation due to the fracture are reduced, the postoperative nail removal is minimally invasive or even avoids secondary operation of nail removal, and the connecting rod fixing device has good clinical transformation significance and application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of material science and medicine, and particularly relates to a connecting rod fixing device for thoracolumbar fracture and a preparation method thereof. BACKGROUND

[0002] With the development of society, the acceleration of modernization process and the acceleration of life rhythm, the incidence of thoracolumbar fracture, especially severe burst fracture, shows an increasing trend. Surgery is the main way to treat thoracolumbar fracture at present, which has been widely carried out in hospitals at all levels, can make patients early ambulation, return to normal work and life, and reduce the burden on family and society. However, most patients still need to undergo a second surgery to remove the titanium alloy connecting rod and pedicle screw used in the first surgery, the purpose of which is to restore the spinal motion function and avoid fatigue fracture of the screw and connecting rod. The secondary surgery brings trauma and economic burden to patients.

[0003] In order to solve the above problems existing in the prior art, the present application is thus obtained. SUMMARY

[0004] In view of the fact that the current titanium alloy connecting rod device only considers the biomechanical properties, and the deficiencies of postoperative screw removal secondary surrounding tissue vascular trauma and screw channel bone repair, the present application provides a connecting rod fixing device for thoracolumbar fracture and a preparation method thereof. The connecting rod fixing device has good biocompatibility, osteogenesis, antibacterial properties and other properties under the premise of meeting the mechanical properties, effectively inhibits postoperative osteogenesis and antibacterial properties of thoracolumbar spine, improves the success rate of surgery, avoids long-term use of antibiotics for anti-infection, reduces the workload when removing the screw, realizes minimally invasive removal of the screw and even avoids secondary surgery for removing the screw, and provides a wider selection for the actual needs of clinical thoracolumbar spine.

[0005] The technical scheme of the present application is as follows:

[0006] The present application relates to a connecting rod fixing device for thoracolumbar fracture, comprising a connecting piece, the connecting piece is rod-shaped and made of titanium alloy, at least one end of the connecting piece is connected with a porous structure piece, the porous structure piece is made of self-dissolving material, the porous structure piece is provided with a three-dimensional interconnected porous structure, the three-dimensional interconnected porous structure is filled with crosslinked hydrogel, the connecting piece is arranged at a fused segment, and the porous structure piece is arranged at a non-fused segment.

[0007] Preferably, the number of the porous structure pieces is two, and one of the porous structure pieces is connected with each end of the connecting piece.

[0008] Preferably, the self-dissolving material is hydroxyapatite; the hydrogel carries bone inductive and antibacterial drugs. In the bone fracture recovery period, the sustained release of bone inductive and antibacterial drugs promotes bone repair, and in the functional recovery period, the self-dissolution of the porous structure of the non-fusion segment restores the spinal motion function, reduces the stress increase of the adjacent segment caused by the fixation of the long segment of the fracture, and reduces the occurrence of degeneration.

[0009] Preferably, the connecting piece and the porous structure are threadedly connected.

[0010] Preferably, the porous structure is composed of a fixed threaded connector and a porous support, the three-dimensionally interconnected porous structure is arranged in the porous support, and the end of the connecting piece is provided with a threaded connection hole matched with the threaded connector.

[0011] Preferably, the three-dimensionally interconnected porous structure is a porous network composed of interconnected pores, and the pore size is 0.8-1.2mm.

[0012] Preferably, the curvature of the connecting rod fixing device is consistent with the physiological curvature of the patient before the injury of the injured vertebra.

[0013] The present application also relates to a preparation method of the connecting rod fixing device for thoracolumbar fracture as described above, comprising the following steps:

[0014] Step 1: constructing a three-dimensional model of the connecting rod fixing device for providing a model for 3D printing;

[0015] Step 2: preparing a 3D printing ink with a self-dissolving material, and printing a porous structure piece provided with a three-dimensionally interconnected porous structure by using a 3D printer;

[0016] Step 3: immersing the porous structure piece in a hydrogel solution for cross-linking reaction, and then freeze-drying in a freeze-drying machine, which causes a large amount of water phase to volatilize, resulting in many space vacancies in the porous structure piece; repeated cross-linking and freeze-drying operations finally make the porous structure piece without space vacancies; this step can obtain secondary micropores by controlling the cross-linking degree and the freeze-drying treatment of the hydrogel after freezing;

[0017] Step 4: connecting the porous structure piece prepared in step 3 with a connecting piece made of titanium alloy to obtain the overall connecting rod fixing device, and further preferably, the connecting piece is made by 3D printing.

[0018] The application uses a cross-linking method instead of a sintering method, the cross-linking process simultaneously loads an antibacterial drug, avoids a series of problems such as great brittleness, low biocompatibility and invalid drug loading caused by segment sintering, simultaneously enables a patient to recover early spinal activity, reduces the risk of adjacent segment degeneration, effectively prevents the risk of broken nails and broken rods caused by stress concentration due to long fixation time of multiple segments after surgery, and restores the non-free body constraint force of the vertebral body outside the injured vertebra, which is beneficial to reduce stress and shear force to share the stress of the injured vertebra.

[0019] Preferably, in step 2, the self-dissolving material is hydroxyapatite powder with a particle size of 25-35 μm; the nozzle diameter of the 3D printer used is 400 μm, the extrusion pressure is 0.4-0.6 MPa, and the printing speed is set to 5-15 mm / s.

[0020] Preferably, in step 3, the hydrogel solution used is a sodium alginate colloidal solution loaded with bone induction and antibacterial drugs, wherein the antibacterial drug is an antibiotic.

[0021] The beneficial effects of the application are:

[0022] (1) The application 3D prints and assembles the traditional titanium alloy material and the self-dissolving material into a connecting rod fixation device, and the porous structure in the non-fusion segment can be selectively self-dissolved in 18-24 months after the surgery, thereby restoring the movement function, reducing the stress increase and degeneration of the adjacent segment caused by long segment fixation of the bone fracture, and making the postoperative nail removal minimally invasive or even avoiding secondary surgery;

[0023] (2) The porous structure of the application is provided with a three-dimensional interconnected porous structure, which provides space support for the hydrogel loaded with osteogenic and antibacterial drugs, and maximally reduces the brittleness against shear force; the self-dissolving porous structure is loaded with osteogenic, antibacterial and other drugs, the slow release of which provides a biological basis for early bone repair and antibiosis, so that the treatment scheme for thoracolumbar fracture is more personalized and more targeted;

[0024] (3) The application has good clinical transformation significance and application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0025] The application will be further described below in combination with the drawings and examples:

[0026] Figure 1 It is a perspective view of the porous structure of the application;

[0027] Figure 2 It is a front view of the porous structure of the application;

[0028] Figure 3 It is a view in the A direction; Figure 2

[0029] ​Figure 4 is a perspective view of the connecting piece of the present application;

[0030] Figure 5 is a sectional view of the connecting piece of the present application;

[0031] Figure 6 is an assembly view of the connecting rod fixing device of the present application.

[0032] In the figure, the reference signs are: 1, connecting piece; 2, porous structure piece; 3, threaded connecting head; 4, porous support; 5, threaded connecting hole. DETAILED DESCRIPTION

[0033] In order to make the object, technical scheme and advantages of the present application more clear and obvious, the present application is further described in detail below in combination with specific embodiments and with reference to the drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of the known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0034] As shown in FIGS. 1 to Figure 6 A connecting rod fixing device for thoracolumbar fracture includes a connecting piece 1 and two porous structure pieces 2, and each end of the connecting piece 1 is connected with one porous structure piece 2. The connecting piece 1 is in the shape of a rod and is made of titanium alloy, and the porous structure piece 2 is made of self-dissolving material, which is hydroxyapatite. The porous structure piece 2 is provided with a three-dimensional interconnected porous structure, which is a porous network composed of interconnected pores, and the size of the pores is 0.8-1.2 mm. The three-dimensional interconnected porous structure is filled with cross-linked hydrogel loaded with bone inductive and antibacterial drugs. The connecting piece 1 is arranged at the fused segment, and the porous structure piece 2 is arranged at the non-fused segment. In the bone fracture recovery period, the sustained release of the bone and antibacterial drugs promotes bone repair. In the functional recovery period, the spinal motion function is restored through the self-dissolution of the porous structure piece 2 of the non-fused segment, thereby reducing the increase of stress and degeneration of adjacent segments caused by long segment fixation of the fracture. As a preferred embodiment, the curvature of the connecting rod fixing device is consistent with the physiological curvature of the patient's injured vertebrae before injury.

[0035] The connecting piece 1 and the porous structure piece 2 are threadedly connected, and the porous structure piece is composed of a threaded connecting head 3 and a porous support 4 connected by the threaded connecting head 3. The three-dimensional interconnected porous structure is arranged in the porous support 4, and the end of the connecting piece 1 is provided with a threaded connecting hole 5 for cooperation with the threaded connecting head 3.

[0036] The preparation method of the connecting rod fixing device specifically includes the following steps:

[0037] Step 1: construct a three-dimensional model of the connecting rod fixation device for providing a model for 3D printing. As preferred, the curvature of the three-dimensional model of the connecting rod fixation device is consistent with the physiological curvature of the injured vertebrae of the patient before injury, specifically by using a three-dimensional modeling software (creo 9.0) to design a connecting rod fixation device (composed of a porous structure and a titanium alloy connecting piece) with a specific physiological curvature.

[0038] Step 2: select hydroxyapatite (HA) powder with a particle size of 25-35 μm to prepare 3D printing ink, and use a 3D printer to print a porous structure with a three-dimensional interconnected porous structure.

[0039] The 3D printer used has a nozzle diameter of 400 um, an extrusion pressure of 0.4-0.6 MPa, a printing speed of 5-15 mm / s, a printing layer thickness of 320 um, and a filling gap of 0.8-1.2 mm. The three-dimensional interconnected porous structure provides space support for the hydrogel loaded with osteogenic and antibacterial drugs, and minimizes the brittleness against shear force.

[0040] Step 3: immerse the porous structure in a sodium alginate colloidal solution loaded with bone induction and antibiotics for crosslinking reaction, and crosslink at room temperature for 24 h to make it completely crosslinked. Then freeze-drying in a freeze-drying machine, the freeze-drying process causes a large amount of water phase to volatilize, resulting in many space vacancies in the porous structure. Repeated crosslinking and freeze-drying operations eventually make the porous structure without space vacancies.

[0041] Step 4: connect the porous structure prepared in step 3 with the connecting piece made of titanium alloy to obtain the overall connecting rod fixation device. The connecting piece is prepared separately and can be made by 3D printing. The fusion segment of the present application is made of traditional titanium alloy material, and the non-fusion segment is made of self-dissolving material. After the fracture heals, part of the connecting rod self-dissolves to restore the motion function of the spine. The present application provides a concept of selectively self-dissolving the connecting rod to restore the motion function of the non-fusion segment after the fracture heals. It not only meets the principle of early strong internal fixation, but also spontaneously restores the motion function of the non-fusion segment.

[0042] The present application provides sufficient mechanical and self-dissolution basis for the connecting rod fixing device through a 3D fine and personalized printing preparation method, and repeated cross-linking processes and screw connecting piece connections. The three-dimensional interconnected porous structure in the porous structure member provides space support for the hydrogel loaded with osteogenic and antibacterial drugs, forms an interpenetrating cross-linked network structure, and enables the porous structure member to have the characteristics of high hardness and low brittleness to resist shear force. Therefore, the connecting rod fixing device material of the present application has sufficient structural stability to function as a fixing support. The present application effectively prevents the risk of broken nails and rods caused by stress concentration due to too long multi-segment fixation time after surgery, minimizes the nail extraction, and even avoids secondary surgery for nail extraction.

[0043] It should be understood that the above specific embodiments of the present application are only used for illustrative or explanatory purposes of the principles of the present application, and do not constitute a limitation on the present application. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present application shall be included in the protection scope of the present application. In addition, the appended claims of the present application are intended to cover all variations and modifications falling within the scope and boundary of the appended claims, or the equivalent forms of such scope and boundary.

Claims

1. A connecting rod fixation device for thoracolumbar fractures, characterized in that, The connecting rod fixing device comprises a connecting rod, which is in the shape of a rod and made of titanium alloy, at least one end of the connecting rod is connected with a porous structure, the porous structure is made of self-dissolving material, the porous structure is provided with a three-dimensional interconnected porous structure, the three-dimensional interconnected porous structure is filled with cross-linked hydrogel, the hydrogel carries bone inductive and antibacterial drugs, and there is no spatial vacancy in the porous structure, the connecting rod is arranged in a fusion segment, and the porous structure is arranged in a non-fusion segment. The three-dimensional interconnected porous structure is a porous network composed of interconnected pores, and the pore size is 0.8-1.2 mm.

2. The connecting rod fixation device for thoracolumbar fracture according to claim 1, characterized by, The number of the porous structures is two, and one of the porous structures is connected with one end of the connecting rod.

3. The connecting rod fixation device for thoracolumbar fracture according to claim 1, characterized by, The self-dissolving material is hydroxyapatite.

4. The connecting rod fixation device for thoracolumbar fracture according to claim 1, characterized by, The connecting rod and the porous structure are screw-connected.

5. The connecting rod fixation device for thoracolumbar fracture according to claim 4, characterized by, The porous structure is composed of a screw joint and a porous support, the three-dimensional interconnected porous structure is arranged in the porous support, and the end of the connecting rod is provided with a screw hole matched with the screw joint.

6. The connecting rod fixation device for thoracolumbar fracture according to claim 1, characterized by, The curvature of the connecting rod fixing device is consistent with the physiological curvature of the injured vertebra of the patient before injury.

7. A method of manufacturing the connecting rod fixation device for thoracolumbar fracture according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: Step 1: constructing a three-dimensional model of the connecting rod fixing device to provide a model for 3D printing; Step 2: preparing 3D printing ink with self-dissolving material, and printing the porous structure provided with a three-dimensional interconnected porous structure by using a 3D printer; Step 3: immersing the porous structure in a hydrogel solution for cross-linking reaction, and then freeze-drying in a freeze-drying machine, the freeze-drying process causes a large amount of water phase to volatilize, resulting in many spatial vacancies in the porous structure, and repeated cross-linking and freeze-drying operations finally make the porous structure have no spatial vacancy; Step 4: connecting the porous structure prepared in step 3 with the connecting rod made of titanium alloy to obtain the whole connecting rod fixing device.

8. The preparation method according to claim 7, characterized in that In step 2, the self-dissolving material is hydroxyapatite powder with a particle size of 25-35 μm, the nozzle diameter of the 3D printer used is 400 μm, the extrusion pressure is 0.4-0.6 MPa, and the printing speed is set to 5-15 mm / s.

9. The preparation method according to claim 7, characterized in that In step 3, the hydrogel solution used is a sodium alginate colloidal solution carrying bone inductive and antibacterial drugs.

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