3D printing porous metal-ceramic assembled composite implant

Abstract

The utility model relates to a 3D printed porous metal-ceramic assembled composite implant as well as a preparation method and application thereof. The 3D printing porous metal-ceramic assembled composite implant comprises a porous metal-ceramic implant body formed by compounding a 3D printing integrated porous metal module and a 3D printing integrated porous ceramic module, the porous metal-ceramic implant body and the net-shaped metal protection body are arranged on the periphery of the porous metal-ceramic implant body in a wrapping mode, and the assembled composite implant can be accurately matched with the appearance and the combination surface of bone tissue of a defect part. The composite implant has osteogenesis environment regulation and control functionalization, the movement function of defective bone tissue can be recovered immediately, the tissue microenvironment of a bone defect part is improved, new bone regeneration is accelerated, new bones are guided to grow towards the interior of the porous metal implant, rapid osseointegration of a bone / metal implant interface is achieved, and the bone / metal implant interface is improved. And the long-term treatment effect of 3D printing porous metal implant / autologous bone fusion type repair after ceramic degradation is achieved.

Description

Technical Field

[0001] This utility model relates to the field of implantable medical device technology, and in particular to a 3D-printed porous metal-ceramic composite implant with osteogenic environment regulation function. Background Technology

[0002] Treatment of various large and segmental bone defects caused by diseases (bone tumors, infections, and congenital malformations) and trauma has long been a challenge in orthopedic clinical practice. Autologous bone transplantation has a relatively ideal regenerative and repair effect. However, this treatment option has limited supply and there are related complications at the bone harvesting site. Although allogeneic bone implants can solve the problem of insufficient autologous bone supply, they also pose risks such as disease transmission and immune rejection. The emergence of artificial bone implants, represented by titanium alloys and bioactive ceramics, has provided new material options for the clinical treatment of various large and segmental bone defects. However, traditional metal implants suffer from poor osseointegration and stress shielding due to a lack of porous structure design, excessively high elastic modulus, and low bioactivity. Although bioactive ceramic implants have better bioactivity and biodegradability, they also have problems such as low mechanical strength and fragility, making them unsuitable for the treatment of complex large and segmental bone defects.

[0003] In recent years, with the application and development of 3D printing technology in the field of medical devices, novel 3D-printed porous implants can significantly reduce the apparent elastic modulus of metal implants and provide growth space for the ingrowth and attachment of new tissue, thereby improving the osseointegration effect at the bone / implant interface. However, clinical studies show that due to the insufficient bioactivity of traditional inert metal materials (titanium and titanium alloys, stainless steel, cobalt-chromium alloys, etc.), 3D-printed porous metal implants still need improvement in terms of bone ingrowth depth, bone repair time, and osseointegration performance. To address this, some studies have proposed filling the internal pores or cavities of 3D-printed porous metal implants with bioceramic powder or particles to improve the bioactivity of the metal implants; however, such methods usually can only be performed by doctors during surgery, which is complex and significantly increases the operation time. Furthermore, the filled ceramic powder / particles lack effective spatial constraints, resulting in a large amount of falling off and migrating within the patient's body, causing complications. Overly tight filling can also block the internal pore structure of the porous metal implant, thereby reducing the implant's vascularization ability and affecting the ingrowth of new bone. Chinese patent number 202220666630.2 discloses a metal prosthesis structure supporting modular ceramics, which involves filling porous ceramic modules one by one inside a metal frame. However, this method uses a solid metal frame, and the excessive elastic modulus of the solid metal can cause a stress shielding effect, leading to bone resorption or even fractures. Furthermore, under the complex stress and micro-strain conditions within the body, the metal frame struggles to effectively protect the ceramics. The ceramic modules (bioactive ceramics such as β-TCP and HA with a porosity of 50% have a compressive strength of only 1-10 MPa) are prone to fragmentation, causing debris migration, physical cuts, or immune responses, increasing the risk of inflammation. Moreover, the metal prosthesis structure cannot adjust the ratio and structural distribution of metal and ceramics according to different surgical treatment needs, resulting in suboptimal repair outcomes. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a 3D-printed porous metal-ceramic composite implant that optimizes and adjusts the distribution and ratio of porous metal and porous ceramic modules according to the bone repair needs of different defect sites. This ensures that the porous metal is within the cell-activating range of the bioactive ceramic, maximizing the osteogenic activity of the porous metal / ceramic composite bone repair implant material. The implant exhibits excellent mechanical, tissue, and structural compatibility. This composite implant features osteogenic environment regulation, enabling immediate restoration of the motor function of the defective bone tissue, improving the tissue microenvironment at the bone defect site, accelerating new bone regeneration and guiding new bone growth into the porous metal implant, achieving rapid bone integration at the bone / metal implant interface, and providing long-term therapeutic effects through fusion repair of the 3D-printed porous metal implant / autologous bone after ceramic degradation.

[0005] To achieve the above objectives, the specific technical solution adopted by this utility model is as follows:

[0006] The 3D-printed porous metal-ceramic composite implant of this invention is characterized by comprising a porous metal-ceramic implant body composed of a 3D-printed integrated porous metal module and a 3D-printed integrated porous ceramic module (also called a porous bioactive ceramic module), and a mesh metal protective body surrounding the porous metal-ceramic implant body. This composite implant can achieve precise matching with the shape and interface of the bone tissue at the defect site.

[0007] The 3D-printed porous metal module in this invention serves two main functions. First, it acts as a load-bearing structure, providing mechanical support and protecting the ceramic implant. This allows for the restoration of the movement function of the defective bone tissue in the early stages of osteogenic development, while simultaneously protecting the porous ceramic from stress damage during surgical procedures and post-implantation use. Second, it facilitates the growth of new bone into the porous metal. The 3D-printed porous bioactive ceramic, acting as an osteogenic environment regulator, primarily improves the tissue microenvironment at the bone defect site, enhances the vascularization and bioactivity of the composite implant, accelerates new bone regeneration, and guides the growth of new bone into the porous metal. This achieves rapid osteointegration at the bone / metal implant interface and long-term therapeutic effects through fusion repair of the 3D-printed porous metal implant / autologous bone after ceramic degradation. Furthermore, the bioactive ceramic can directly contact the bone tissue end face or periosteum, maximizing its osteogenic environment regulation and promoting osteogenic effects. In the final stages of implantation, with complete ceramic degradation and new bone remodeling, the autologous bone and porous metal implant achieve integrated fusion, realizing a mutually supportive bone repair effect.

[0008] Furthermore, since the regulatory effect of bioactive ceramics on the tissue microenvironment is limited, the ratio and distribution of porous metal and ceramic can be adjusted according to the repair needs of different bone defect sites. For example, porous ceramic modules can be assembled on one side of a porous metal module to form a lateral porous metal-ceramic composite implant body (referred to as a lateral implant body, also called a one-sided implant body). Alternatively, porous ceramic modules can be assembled in the center of a porous metal module to form a central porous metal-ceramic composite implant body (referred to as a central implant body). For instance, large bone defects in load-bearing bones require high mechanical support, necessitating an increased proportion of porous metal and its distribution at the main stress points to enhance support and stability, while porous ceramic is placed in non-main stress areas to improve the osteogenic environment of the implant. In principle, the ceramic proportion should be increased as much as possible while ensuring mechanical stability to enhance bone repair performance and achieve rapid healing. In the repair of joints such as the spine, a combination method can be adopted, in which porous ceramics are added to the central unloaded area and porous metals are used in the peripheral load-bearing area. This maximizes the bone repair performance of the implant while ensuring mechanical stability, ensuring that the entire implant is within the optimal control range of the ceramic. This maximizes the mechanical and osteogenic activity of the 3D-printed porous metal / ceramic composite bone repair implant material, giving full play to the optimal osteogenic environment regulation and osteopromoting effect of bioactive ceramics, and accelerating bone integration and bone healing. The bioactive ceramics in this invention can directly contact the end face of bone tissue or the periosteum.

[0009] Furthermore, the mesh metal protective body is a protective sleeve formed by at least two honeycomb mesh panels fastened together.

[0010] This utility model also includes a locking steel plate that is customized according to the bone morphology, and the locking steel plate is connected to the metal protective body. Further, the mesh metal protective body is provided with a snap-fit ​​structure, and the locking steel plate is correspondingly provided with a snap-fit ​​structure that can be assembled with the snap-fit ​​structure on the metal protective body. Through the snap-fit ​​structure on the mesh metal protective body, a tight assembly of the mesh metal protective body, porous metal module, porous ceramic module, composite implant, and locking steel plate can be achieved. The snap-fit ​​structure on the mesh metal protective body and the snap-fit ​​structure on the locking steel plate can be set as needed. For example, the snap-fit ​​structure includes at least two sets of snap blocks on the sides of the two honeycomb mesh panels and snap sleeves for inserting and snapping the snap blocks. The snap-fit ​​structure on the locking steel plate is a snap-fit ​​groove for inserting and positioning the snap blocks and snap sleeves.

[0011] The functions of the mesh metal protective body in this invention are: 1. To connect the porous metal-ceramic implant body and the locking steel plate, serving as the connection point for the assembly of various components; 2. The mesh metal protective body structure prevents the ceramic portion from fractured under shear stress or impact; 3. The mesh metal protective body acts as a limiting element, restricting the movement of ceramic fragments in the event of fracture, preventing them from migrating to other non-defective areas and causing immune reactions or cutting normal tissue. The mesh metal protective body is a porous protective sleeve structure with a pore size ranging from 1-10 mm, preferably around 5-8 mm.

[0012] The porous metal module and porous ceramic module of this invention are either truss-type porous structures or sheet-type porous structures with through holes. The pore diameter of the porous metal module and porous ceramic module ranges from 300-1000μm, and the porosity ranges from 40%-90%.

[0013] The ratio and distribution of porous metal and ceramic in the composite implant of this invention can be customized according to the patient's defect location. Generally, the proportion of porous metal modules is greater than 0 and less than or equal to 80%; the proportion of porous ceramic modules is at least 20%. The total ratio of porous ceramic modules and porous metal modules is 100%. Preferably, the proportion of porous metal modules is 10%-80%, and the proportion of porous ceramic modules is 20%-90%. More preferably, the proportion of porous metal modules is 30%-80%, and the proportion of porous ceramic modules is 20%-70%. Specifically, for the repair of non-weight-bearing long bones and large segments of non-femoral bone defects, a lateral porous metal-ceramic composite implant body with a porous metal module ratio greater than 0 and less than 50% is selected; for the repair of large segments of femoral bone defects, a lateral porous metal-ceramic composite implant body with a porous metal module ratio of 50% or a central porous metal-ceramic composite implant body with a porous metal module ratio of 30%-70% is selected.

[0014] Compared with the prior art, this utility model has the following advantages:

[0015] (1) The most significant feature of the 3D printed porous metal-ceramic composite implant designed in this utility model is that the ratio and distribution of the porous metal module (also called porous metal implant) and the porous ceramic module (also called porous ceramic implant) can be adjusted according to the needs of surgical treatment, thereby maximizing the mechanical and osteogenic activity of the 3D printed porous metal / ceramic composite bone repair implant material, giving full play to the best osteogenic environment regulation and osteogenic effect of bioactive ceramics, and accelerating bone integration and bone healing.

[0016] (2) This utility model can also adjust the size and shape of the composite implant (e.g., the porous metal module and porous ceramic module are 3D personalized printed according to the specific situation, conforming to the shape of the bone in the defect site) and the size and curvature of the locking plate according to the bone shape and size of different defect sites; the method of assembling the porous metal and porous ceramic composites and the shape of the composite implant can be adjusted according to different surgical sites to achieve personalized and precise repair. The locking plate and the composite implant are assembled in a way that allows the locking plate to be removed as needed after bone healing, avoiding the locking plate affecting subsequent healing in the body.

[0017] (3) In this invention, the porous bioactive ceramic can promote bone regeneration, achieve rapid bone integration in the early stage of healing, and prevent nonunion or fibrous tissue ingrowth; in the middle stage of healing, it guides new bone to grow into the porous metal, enabling the composite implant and the host bone to form bony healing, effectively solving delayed healing and implant connection loosening and displacement; in the late stage of healing, with the degradation of ceramic and the ingrowth of new bone, the implant and the host bone form bony healing (which can achieve the integrated fusion of the host bone and the porous metal implant, achieving the bone repair effect of "you in me, supporting each other"), and finally achieve partial regeneration and repair of segmental and large-segment weight-bearing bone defects; the metal part, as the main weight-bearing part, can provide mechanical support for the patient in the early stage of implantation, and at the same time protect the ceramic implant from being crushed or failing. This modular implant of the present invention solves the problem that existing implants cannot achieve regeneration and repair when repairing weight-bearing parts, and can achieve partial regeneration and repair as bone healing progresses and ceramics degrade.

[0018] (4) The 3D-printed integrated porous ceramic module forms a support structure with a certain supporting function. The integrated structure will not detach, effectively solving the problems of ceramic filling composite implants or ceramic coating composite implants, which are prone to ceramic failure or easy detachment and migration to other parts. In addition, since the ceramic and metal parts assembled in the modular composite implant are 3D-printed integrated structures, they both have a certain supporting function for the bone. They will be subjected to stress during daily activities after implantation. Under the action of micro-stress, new bone formation can be promoted, preventing delayed healing and bone resorption caused by lack of stress (because bone formation is a matter of use and disuse. If there is no micro-stress stimulation, it will delay healing or bone resorption, resulting in non-bone formation or nonunion in that area). Moreover, the composite implant can adjust the metal-ceramic ratio according to the stress requirements of the bone defect site, which can effectively control the stress loaded on the ceramic, avoiding bone resorption caused by insufficient ceramic stress, and also avoiding ceramic fracture failure caused by excessive ceramic stress. The composite implant and locking plate of this invention are obtained by reverse extraction of the defect model, which reconstructs the force line of the defect site, so that the host bone and the composite implant are subjected to uniform force, avoiding uneven force or stress concentration.

[0019] The present invention will be further described below with reference to the accompanying drawings. Attached Figure Description

[0020] Figure 1 This is a perspective view of the first embodiment of the present invention combined with the locking steel plate.

[0021] Figure 2 for Figure 1 A top-view structural diagram.

[0022] Figure 3 for Figure 1 A schematic diagram of the structure of a porous ceramic module.

[0023] Figure 4 for Figure 2 Schematic diagram of a porous metal module structure.

[0024] Figure 5 for Figure 1 A three-dimensional view of the combination of porous metal modules and porous ceramic modules.

[0025] Figure 6 for Figure 1 A schematic diagram of the assembly structure.

[0026] Figure 7 This is a perspective view of the central implant body according to the second embodiment of the present invention.

[0027] Figure 8 for Figure 7 Top view.

[0028] Figure 9 This is a perspective view of the mesh metal protective body of this utility model.

[0029] Figure 10 This is a perspective view of the locking steel plate of this utility model.

[0030] Figure 11 for Figure 7 The assembly diagram is shown below.

[0031] Figure 12 This is an isometric view of the finite element mechanical simulation of the 3D printed porous metal-ceramic composite implant of this utility model.

[0032] Figure 13 This is a front view of the finite element mechanical simulation of the 3D printed porous metal-ceramic composite implant of this utility model.

[0033] Figure 14 The gradient of calcium and phosphorus ion concentrations released from the degradation of bioactive ceramics in the tissue-mimicking microenvironment of GelMA hydrogel as a function of distance.

[0034] Figure 15a The effect of changes in calcium and phosphorus ion concentration gradients on cell proliferation behavior.

[0035] Figure 15b The effect of changes in calcium and phosphorus ion concentration gradients on cell adhesion and differentiation behavior.

[0036] Figure 15c The effect of changes in calcium and phosphorus ion concentration gradients on osteogenic differentiation behavior of cells.

[0037] Figure 16 This is a surgical implantation diagram of the 3D-printed porous metal-ceramic composite implant of this utility model.

[0038] Figure 17a MASSON stained sections of 3D printed porous metal-ceramic composite implants with different assembly methods (central and side-assembly) of porous metal and porous ceramics according to this utility model.

[0039] Figure 17b These are magnified images of MASSON stained sections of the 3D-printed porous metal-ceramic composite implant of this invention, including sections inside the ceramic, at the metal-ceramic interface, and within the metal.

[0040] Figure 18 The bone repair effects of 3D-printed porous ceramic implants and 3D-printed porous metal implants.

[0041] Figure 19 This invention demonstrates the bone repair effect of 3D-printed porous metal-ceramic composite implants with different proportions of metal and ceramic.

[0042] Figure 20 This is a perspective view of the third embodiment of the present invention combined with a locking steel plate.

[0043] Figure 21 This is a perspective view of the fourth embodiment of the present invention combined with a locking steel plate.

[0044] Figure 22 This is a 3D view of Comparative Example 1 combined with a locking steel plate (100% porous metal module, 0% porous ceramic module).

[0045] Figure 23 This is a 3D view of Comparative Example 2 combined with a locking steel plate (0% of the porous metal module and 100% of the porous ceramic module).

[0046] Figure 24 This is a perspective view of the fifth embodiment of the present invention combined with a locking steel plate (the porous metal module accounts for 50%, and the porous ceramic module accounts for 50%). Detailed Implementation

[0047] The 3D-printed porous metal-ceramic composite implant of this invention comprises a porous metal-ceramic composite implant body assembled from a 3D-printed integrated porous metal module 11 and a 3D-printed integrated porous ceramic module 12, and a mesh metal protective body 13 surrounding the porous metal-ceramic composite implant body. Together, these components form a composite implant (hereinafter referred to as the implant) capable of precisely matching the shape and interface with the bone tissue at the defect site. An integrated locking plate 14 can also be designed on the implant, or other non-integrated locking plates can be used. The locking plate can be a detachable or non-detachable structure. The locking plate can be customized according to the bone shape; the size and curvature of the implant and plate can be adjusted according to the shape and size of the bone defect at different locations; the shape of the implant can be adjusted according to different surgical sites to achieve personalized and precise repair. The 3D-printed porous metal module and 3D-printed porous ceramic module in this invention are assembled together, enabling rapid osseointegration and guiding bone growth into the metal, shortening the bone healing time and promoting the depth of host bone ingrowth. This addresses the challenges of slow bone integration, nonunion, and fibrous tissue encapsulation in the treatment of segmental and large-segment weight-bearing bone defects.

[0048] Furthermore, since the regulatory effect of bioactive ceramics on the tissue microenvironment is limited, the ratio and distribution of metal and ceramic can be adjusted according to the repair needs of different bone defect sites. For example, porous ceramic modules can be assembled on one side of a porous metal module to form a side-mounted porous metal-ceramic composite implant. Alternatively, porous ceramic modules can be assembled at the center of a porous metal module to form a centrally mounted porous metal-ceramic composite implant. The ratio of the 3D-printed porous metal module and the 3D-printed porous ceramic module can be adjusted according to the load-bearing requirements of different sites. Specifically, while meeting mechanical support requirements, the proportion of the ceramic module is maximized. This design fully utilizes the excellent biocompatibility and bone integration performance of bioactive ceramics, while providing necessary mechanical support through the porous metal module and mesh metal protector, ensuring the load-bearing capacity and stability of the structure. By optimizing the distribution ratio of metal and ceramic, the best balance between mechanical properties and biointegration performance can be achieved, thereby improving the overall functionality and effectiveness of the implant. Generally, the proportion of the porous metal module is greater than 0 and less than or equal to 80%; the proportion of the porous ceramic module is at least 20%. For repairing large segmental bone defects outside the femur, a lateral porous metal-ceramic composite implant body with 30%-50% porous metal modules is selected; for repairing large segmental bone defects of the femur, a lateral porous metal-ceramic composite implant body with 50% porous metal modules or a central porous metal-ceramic composite implant body with 50%-70% porous metal modules is selected.

[0049] In animal experiments using New Zealand white rabbits, a large segmental bone defect model of the right femur with a defect length 1.61 times its width was selected. This study demonstrated that a lateral porous metal-ceramic composite implant with a 50% porous metal module and a 50% porous ceramic module exhibited the best repair effect, showing the highest osteogenic volume and bone ingrowth depth. The second best result was achieved with a central porous metal-ceramic composite implant with a 50% porous metal module and a 50% porous ceramic module. Because the porous ceramic module was located in the middle at the contact point with the femoral cortex, its bone ingrowth depth was insufficient in the early stages of treatment, although new bone formation occurred within both the porous metal and porous ceramic modules. Therefore, the central porous metal-ceramic composite implant demonstrates better mechanical properties than the lateral porous metal-ceramic composite implant, making it suitable for repairs with higher mechanical requirements, such as supercritical femoral bone defects. The lateral-fitting composite implant body of the 70% porous metal module and 30% porous ceramic module (hereinafter referred to as 70% metal-30% ceramic) shows bone ingrowth depth of up to 4 structural units (i.e., 4 mm) within the porous metal adjacent to the β-TCP and femur. With increasing distance, the amount of bone formation within the porous metal decreases significantly, indicating that the regulatory effect of β-TCP on the tissue microenvironment decreases significantly with increasing distance. Therefore, the amount of bone formation within the porous metal far from the femur and β-TCP is significantly reduced. In the lateral-fitting composite implant body of the 30% porous metal module and 70% porous ceramic module, a large amount of new bone formation can be observed within the porous ceramic, gradually migrating and growing into the porous metal. However, microfractures sometimes occur in the ceramic, posing a certain risk. Therefore, a mesh metal protective body is needed to provide auxiliary mechanical support and protection. The composite implant body made of 100% porous ceramic modules cannot provide mechanical support, leading to malunion. The composite implant body made of 100% porous metal modules does not achieve bony fusion with the bone, easily causing implant loosening, pain, and in severe cases, fracture. In the experiment, because the rabbit model used has thinner cortical bone and rabbits primarily jump, they experience greater impact and pressure than when walking, making them more prone to fracture. Therefore, the experiment mainly selected an example of a 50% porous metal module-50% porous ceramic module combination for comparison with other examples. The experimental comparison showed that for the repair of non-femoral large-segment bone defects, a lateral approach composite implant body with 30%-50% porous metal modules can be selected. For large-segment femoral bone defects, a lateral approach composite implant body with 50% porous metal modules or a central composite implant body with 50%-70% porous metal modules can be selected. For supercritical femoral bone defects, a central composite implant body with more than 70% porous metal modules can be selected. To ensure bone formation and osseointegration performance, the ceramic proportion should be at least 20%, and ceramic components should be placed near the four metal unit structures to regulate the osteogenic environment and guide bone growth inward.

[0050] The 3D-printed porous metal module and 3D-printed porous ceramic module of this invention preferably have a truss-type porous structure or a highly interconnected sheet-type porous structure, which can support cell adhesion and growth, and provide space for new bone ingrowth and vascular network extension.

[0051] The present invention will be further described below through specific embodiments.

[0052] First Embodiment

[0053] This embodiment provides a design for a 3D-printed porous metal-ceramic composite implant for the repair of segmental, large-segment weight-bearing bone defects.

[0054] Taking a side-joint 3D-printed porous metal-ceramic composite implant as an example, such as Figure 1 , Figure 2 and Figure 3 As shown, the porous metal module accounts for 50%, the porous ceramic module accounts for 50%, and the composite implant consists of four parts: a 3D-printed integrated porous metal module 11, a 3D-printed integrated porous ceramic module 12, a 3D-printed honeycomb mesh metal protector 13, and a 3D-printed locking steel plate 14. The locking steel plate 14 has locking screw tracks 15, and the mesh metal protector has a snap-fit ​​structure 16, which serves to connect the various parts for assembly.

[0055] It should be noted that the porous metal module and porous ceramic module, when assembled, precisely match the shape of the defect, which helps to restore the original force line of the defect and avoid deformities after healing or stress concentration and changes in the stress environment caused by force line misalignment, leading to loosening, pain, deformity, or fracture. The metal part can be medical-grade titanium and titanium alloys, 316L stainless steel, tantalum metal, etc., and this invention uses Ti6Al4V alloy as an example. The metal part is preferably formed using powder bed additive manufacturing technology, and this invention uses SLM 3D printing technology as an example. The ceramic part can be calcium phosphate bioactive ceramics, bioglass, magnesium white calcium phosphate, etc., and this invention uses β-tricalcium phosphate (β-TCP) as an example.

[0056] Second embodiment: as follows Figure 20 As shown, this is a side-fitting 3D-printed porous metal-ceramic composite implant body, with the porous metal module accounting for 30% and the porous ceramic module accounting for 70%. The rest is the same as above. This embodiment is a preferred solution.

[0057] Third embodiment: Figure 21 As shown, this is the body of a porous metal-ceramic composite implant manufactured using a side-fitting 3D printing method. The porous metal module accounts for 70%, and the porous ceramic module accounts for 30%. The rest is the same as above.

[0058] Comparative Example 1: Figure 22 The image shows an implant body consisting of 100% porous metal modules and 0% porous ceramic modules. The rest is the same as above.

[0059] Comparative Example 2: Figure 23 As shown, this is an implant body with 0% porous metal modules and 100% porous ceramic modules. The rest is the same as above.

[0060] Fourth embodiment: Figure 24 The image shows a centrally located 3D-printed porous metal-ceramic composite implant. The porous metal module comprises 50% of the implant, and the porous ceramic module comprises 50%, with the porous ceramic module in the center and the porous metal module surrounding it. The rest is the same as above. This embodiment is a preferred embodiment.

[0061] Figure 18 The images show Masson staining images 12 weeks after implantation of a 100% porous ceramic module composite implant and a 100% porous metal module implant in the repair of large segmental femoral bone defects. The images show that in the comparative example using the 100% porous ceramic module composite implant, although there was significant new bone formation, the locking plate and mesh metal protector alone could not provide the necessary mechanical support, leading to fracture of the porous ceramic module and malunion (inward concavity of the proximal femoral autologous bone). In the comparative example using the 100% porous metal module implant, only a small amount of bone ingrowth occurred at the contact point with the autologous bone within the porous metal module; no bone ingrowth occurred deep within the porous metal. The composite implant and bone did not achieve osteofusion, making it prone to fracture under stress. Therefore, both methods have drawbacks in the treatment of large segmental weight-bearing bone defects. Figure 17a Examples of lateral and central porous metal-ceramic composite implants in this study demonstrate that the composite implants essentially ensure mechanical stability while promoting bone repair.

[0062] In addition, in this invention, for non-weight-bearing long bones such as the fibula, clavicle, and radius, if the defect does not reach the level of a large segmental bone defect (a large segmental bone defect is defined as a bone defect whose length is more than 1.5 times its width), the proportion of porous ceramic modules can be increased to nearly 100%. Relying on locking plates and mesh metal protection to prevent fractures caused by impact and shear stress, the mechanical requirements for repair can be basically met. If the defect reaches the length of a large segmental bone defect, the proportion of porous metal modules can be increased to improve its support. For example, a lateral or central porous metal-ceramic composite implant comprising 30% porous metal modules and 70% porous ceramic modules can be used. This maximizes the ceramic proportion while meeting the needs of daily activities, accelerating the bone repair process. In the repair of weight-bearing long bones such as the tibia and humerus, due to their higher mechanical requirements, the metal proportion can be increased to avoid complications such as fractures caused by implant breakage. A lateral or central porous metal-ceramic composite implant comprising 50% porous metal modules and 50% porous ceramic modules can be used. For example, in the femur, the largest weight-bearing bone, animal experiments suggest that the proportion of metal in the repair of large bone defects may be increased to 50% or 70%. This can be achieved using a lateral or central porous metal-ceramic composite implant comprising 50% porous metal modules and 50% porous ceramic modules, or a lateral or central porous metal-ceramic composite implant comprising 70% porous metal modules and 30% porous ceramic modules. In more extreme cases of bone defects, such as supercritical femoral defects caused by the resection of large bone tumors, the proportion of porous metal modules can be increased to 80%. The implant body is designed with a central porous ceramic module structure and an outer porous metal module structure to ensure mechanical requirements and maximize ceramic coverage to promote repair. When the proportion of porous metal modules reaches 80% and the porous ceramic module reaches 20%, the distal end of the porous metal module in the central implant body is precisely within approximately four structural units of the porous ceramic module, which is within the optimal range for ceramic osteogenic environment regulation. If the proportion of porous metal modules exceeds 80% and porous ceramic modules is less than 20%, calcium and phosphorus ions released from ceramic degradation will have difficulty migrating to the porous metal modules located far from the ceramic part. This makes it difficult to effectively regulate the osteogenic environment, leading to weakened expression of local microenvironment osteogenic genes (such as OCN, OPN, ALP, etc.), resulting in insufficient osteogenic performance within the modules. Consequently, bone will have difficulty ingrowing into the porous metal modules located far from the ceramic part. In addition, the reduced concentration of calcium and phosphorus ions will also lead to increased expression of osteoclast-related genes such as TRAP, causing abnormal healing and bone resorption. This can result in the formation of cavities or fibrous tissue encapsulation within the metal in the area far from the ceramic, increasing the risk of aseptic inflammatory reactions. Furthermore, insufficient bone ingrowth in this area can lead to abnormal stress conditions in the implant cavity during the later stages of healing, i.e., uneven stress causing stress concentration or bone resorption, increasing the risk of implant loosening, and may even lead to osteophytes and malunion.

[0063] The method for constructing the above-mentioned 3D-printed porous metal-ceramic composite implant includes the following steps:

[0064] (1): Based on the Micro-CT scan data of the defect model, feature parameters are extracted and three-dimensional reconstruction is performed. The shape of the composite implant is personalized and precisely designed using three-dimensional drawing software. According to the osteogenic and load-bearing requirements of the defect site, modular segmentation is performed, and the proportion and distribution of porous metal modules and porous ceramic modules are set, and the shape is adjusted.

[0065] (2): 3D printed integrated porous metal module with a porosity of 70% and a pore size of 700μm.

[0066] (3): A 3D-printed integrated porous ceramic module with a porosity of 65% and a pore size of 800μm. After printing, it is dried in a drying oven, followed by degreasing and sintering.

[0067] (4): 3D printed mesh (e.g., honeycomb) metal protective body parts, designed as follows Figure 9 As shown, the mesh protective body is formed by two half-sided honeycomb mesh panels fastened together. The fastening structure on it includes four clips and clip sleeves, which serve to connect and assemble the parts.

[0068] (5): After assembling the porous metal module and the porous ceramic module as required, a composite implant body is formed. Then, after inserting the assembled composite implant body into the open mesh metal protective body, the buckles on the opposite sides of the two hemispherical honeycomb mesh plates are aligned and inserted to complete the assembly of the composite implant, thereby obtaining a 3D printed porous metal-ceramic assembled composite implant that precisely matches the shape and interface of the bone tissue at the defect site.

[0069] Alternatively, a locking steel plate can be 3D printed before assembly. The assembled composite implant can then be installed on the locking steel plate using a mesh metal protective structure.

[0070] Figure 12 As shown, the finite element simulation of the implant after being subjected to compressive and torsional stresses is an isometric view, indicating that the implant is subjected to uniform stress and there is no stress concentration.

[0071] Figure 13 As shown, this is the main view of the finite element simulation of the implant after being subjected to compressive and torsional stresses. The implant is subjected to uniform stress with no stress concentration.

[0072] like Figure 14As shown, the concentration gradient of calcium and phosphorus ions released from the degradation of bioactive ceramics in the tissue-mimicking microenvironment of GelMA hydrogel varies with distance. Under the condition of resisted diffusion in the tissue microenvironment, the calcium and phosphorus ions released from the degradation of bioactive ceramics form a spatial concentration gradient. Specifically, the concentration of calcium and phosphorus ions increases significantly near the bioactive ceramics, but gradually decreases with increasing distance. This gradual decrease in ion concentration indicates that the regulatory effect of bioactive ceramics on the tissue microenvironment is limited, and also suggests that the distribution and ratio of metal and ceramic have a significant impact on the repair effect of the implant.

[0073] like Figure 15a As shown, the effects of changes in calcium and phosphorus ion concentration gradients on cell proliferation behavior are illustrated. Near the bioactive ceramic, calcium and phosphorus ion concentrations significantly increase, regulating cell proliferation behavior; however, with increasing distance, calcium and phosphorus ion concentrations gradually decrease, and their regulatory capacity on the extracellular matrix microenvironment and cell proliferation behavior gradually weakens.

[0074] like Figure 15b As shown, the effect of changes in calcium and phosphorus ion concentration gradients on cell adhesion behavior is investigated. Near the bioactive ceramic, regulating cell adhesion behavior significantly increases the cell spreading area; however, with increasing distance, the cell spreading area significantly decreases.

[0075] like Figure 15c As shown, the effects of calcium and phosphorus ion concentration gradients on osteogenic differentiation behavior are investigated. Near the bioactive ceramic, calcium and phosphorus ion concentrations significantly increase, activating the Wnt / β-catenin signaling pathway and regulating cellular behaviors such as osteogenic differentiation, with a significant upregulation of osteogenic-related gene expression. Conversely, with increasing distance, calcium and phosphorus ion concentrations gradually decrease, and their regulatory capacity on the extracellular matrix microenvironment and cell differentiation behavior gradually weakens. These results suggest that optimizing the distribution and ratio of 3D-printed porous metal and ceramic modules can maximize the osteogenic performance of 3D-printed porous metal / ceramic modular bone repair implants.

[0076] like Figure 16 As shown, after the implant is inserted into the femur of a New Zealand white rabbit, the implant can be personalized and precisely repaired to restore the shape of the defect and restore the original force line of the bone.

[0077] like Figure 17a The image shows Masson staining images of hard tissue sections from implants with different distributions of porous metal and porous ceramic 12 weeks after implantation. In both centrally located and laterally located composite implants, under the influence of ceramic, a large amount of new bone tissue is also present within the porous metal module, demonstrating the migration and growth of new bone from the ceramic interior to the metal interior.

[0078] like Figure 17bAs shown, Masson staining of hard tissue sections 12 weeks after implantation reveals extensive new bone formation within the ceramic. Calcium and phosphorus ions released during ceramic degradation diffuse into the metal, improving the internal microenvironment, which in turn leads to the visible migration and growth of new bone within the metal.

[0079] like Figure 18 The image shows Masson staining images of hard tissue sections 12 weeks after implantation of 3D-printed porous ceramic implants and 3D-printed porous metal implants. In the repair of segmental and large-segment bone defects in weight-bearing bones, even with the support of internal fixation plates, 3D-printed porous ceramic implants cannot provide adequate mechanical support. Fracture of the ceramic portion leads to dislocation and deformation of both the proximal and distal femurs, resulting in malunion. Due to the extreme osteogenic environment in the repair of segmental and large-segment bone defects in weight-bearing bones, 3D-printed porous ceramic implants result in insufficient osseointegration and bone ingrowth depth. Only 2-3 bone units are ingrowth deep near the end of the implant; no new bone formation is observed in the rest of the implant. Meanwhile, medullary canal closure has occurred in the distal femur, which can be preliminarily diagnosed clinically as nonunion. Because there is no bony union between the implant and the autologous bone, long-term implantation can lead to implant loosening or even fracture.

[0080] like Figure 19 As shown, hard tissue sections of composite bone repair implants with different proportions of porous metal and porous ceramic are stained with methylene blue-basic fuchsin. In the metal (30%)-ceramic (70%) composite implant, the porous metal portion is within the optimal osteogenic regulation range of the ceramic, with new bone formation within it, exhibiting good osseointegration, new bone volume, and bone ingrowth depth. The metal (70%)-ceramic (30%) composite implant shows good osseointegration on the side closer to the ceramic (within approximately 4 structural units), while minimal new bone formation is observed further away from the ceramic (beyond 4 structural units). This conclusion also suggests that the diffusion of calcium and phosphorus ions released from the degradation of bioactive ceramics in the osteogenic environment of the defect site in vivo will also create differences in ion concentration and spatial distribution, and the spatial distribution of ions will also have a significant impact on the bone repair performance of the composite implant. Therefore, when designing metal / ceramic composite implants, the composite configuration should be fully considered. Under the premise of ensuring the mechanical stability of the implant, optimizing and increasing the proportion of bioactive ceramics in the composite implant can give full play to its regulatory role on the osteogenic environment, realize the effective regulation of the osteogenic environment in the defect area by the composite implant, and improve the overall bone repair performance of the implant.

[0081] As described above, the present invention can be well implemented. The above embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made in accordance with the content of the present invention are covered by the scope of protection claimed by the claims of the present invention.

Claims

1. A 3D-printed porous metal-ceramic composite implant, characterized in that... : Including a porous metal-ceramic composite implant body composed of a 3D-printed integrated porous metal module (11) and a 3D-printed integrated porous ceramic module (12) combined together, and a mesh metal protective body (13) surrounding the porous metal-ceramic composite implant body, which can precisely match the shape and interface of the bone tissue at the defect site.

2. The 3D-printed porous metal-ceramic composite implant according to claim 1, characterized in that: The porous ceramic module (12) is assembled on one side of the porous metal module (11) to form a side-fitted porous metal-ceramic composite implant body.

3. The 3D-printed porous metal-ceramic composite implant according to claim 1, characterized in that: The porous ceramic module (12) is assembled at the center of the porous metal module (11) to form a central porous metal-ceramic composite implant body.

4. The 3D-printed porous metal-ceramic composite implant according to claim 1, characterized in that: The mesh metal protector (13) is a protective sleeve formed by fastening together the sides of at least two honeycomb mesh panels.

5. The 3D-printed porous metal-ceramic composite implant according to claim 1 or 4, characterized in that: It also includes a locking plate (14) that is individually designed according to the shape of the bone, which is connected to the mesh metal protector (13).

6. The 3D-printed porous metal-ceramic composite implant according to claim 5, characterized in that: The mesh metal protector (13) is provided with a snap-fit ​​structure (16), and the locking steel plate (14) is provided with a corresponding snap-fit ​​structure that can be assembled with the snap-fit ​​structure (16) on the mesh metal protector (13). Through the snap-fit ​​structure (16) on the mesh metal protector (13), the mesh metal protector, porous metal module, porous ceramic module, composite implant, and locking steel plate can be tightly assembled.

7. The 3D-printed porous metal-ceramic composite implant according to claim 1, characterized in that: The mesh metal protective body (13) is a protective sleeve formed by fastening the sides of two honeycomb mesh panels. The buckle structure (16) consists of at least two sets of buckles on the sides of the two honeycomb mesh panels and buckles for the buckles to be inserted and snapped. The locking structure on the locking steel plate (14) is a snap-fit ​​groove for the buckles and buckles to be inserted and positioned.

8. The 3D-printed porous metal-ceramic composite implant according to claim 1, characterized in that: The porous metal module (11) and the porous ceramic module (12) are either truss-type porous structures or sheet-type porous structures with through holes.

9. The 3D-printed porous metal-ceramic composite implant according to claim 1, characterized in that: In the porous metal-ceramic composite implant body, the proportion of porous metal module (11) is greater than 0 and less than or equal to 80%; the proportion of porous ceramic module (12) is at least 20%, and the sum of porous ceramic module and porous metal module is 100%.

10. The 3D-printed porous metal-ceramic composite implant according to claim 9, characterized in that: For the repair of non-weight-bearing long bones and large segments of non-femoral bone defects, a lateral porous metal-ceramic composite implant body with a porous metal module (11) ratio greater than 0 and less than 50% is selected; for the repair of large segments of femoral bone defects, a lateral porous metal-ceramic composite implant body with a porous metal module (11) ratio of 50% or a central porous metal-ceramic composite implant body with a porous metal module (11) ratio of 30%-70% is selected.

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