Knee joint prosthesis fixing device matched with bionic meniscus mechanics

Abstract

The invention discloses a bionic meniscus mechanical adaptive knee joint prosthesis fixing device which comprises a tibia, a meniscus prosthesis, a fractal porous anchor and a shape memory polymer sleeve, the meniscus prosthesis is arranged on a platform of the tibia, the fractal porous anchor penetrates through the meniscus prosthesis and extends into the tibia, so that the meniscus prosthesis is fixed on the tibia platform, and the shape memory polymer sleeve is arranged in the shape memory polymer sleeve. The fractal porous anchor is of a gradient pore structure and can be directly inserted into bone tissue to form a minimally invasive channel, the shape memory polymer sleeve wraps the middle section, extending into the tibia, of the fractal porous anchor, the shape memory polymer sleeve shrinks at low temperature, and the glass transition temperature of the shape memory polymer sleeve is 31-38 DEG C. The three core problems that a traditional knee joint prosthesis is high in loosening rate, rapid in abrasion and poor in adaptability are solved, an innovative solution is provided for the field of orthopedic implants, and the knee joint prosthesis particularly conforms to the development trend of precise medical treatment and rapid rehabilitation surgery.

Description

TECHNICAL FIELD

[0001] The application relates to a knee prosthesis fixing device with biomechanical adaptation of a meniscus, and belongs to the technical field of medical devices. BACKGROUND

[0002] As an important cushioning structure in the knee joint cavity, the meniscus often suffers secondary tearing or wear due to acute knee injury or joint degenerative disease, causing joint swelling and movement disorders, and is a common sports injury. However, the self-repairing ability of the meniscus after injury is limited. The biomechanical meniscus refers to a medical device that simulates the structure and function of the natural meniscus and can adapt to the biomechanical requirements of the knee joint.

[0003] In the current medical technology, the application of the biomechanical meniscus has been realized, such as the patent: a meniscus prosthesis (patent application number: 202410386555.8). However, in the prior art, the fixing method often uses suture fixation technology, conventional anchor fixation technology, bone cement fixation and the like, and the existing biomechanical meniscus fixing method has the following defects:

[0004] The suture fixation technology uses high-strength suture (such as UltraHigh Molecular Weight Polyethylene suture) to suture the edge of the biomechanical meniscus to the joint capsule or residual meniscus tissue, and common methods include vertical mattress suture, horizontal suture and the like, however, it has the following disadvantages: the local stress of the suture point is too high, which easily leads to suture cutting or tissue tearing; the suture cannot dynamically adjust the tension with the movement of the knee joint, which leads to the displacement or micro-motion wear of the meniscus; the risk of suture degradation or fatigue fracture significantly increases 3-5 years after the operation.

[0005] The conventional anchor fixation technology uses metal (titanium alloy) or absorbable material (PLLA) anchor, and the meniscus prosthesis is anchored to the edge of the tibial plateau through pre-drilling, however, it has the following disadvantages: the drilling destroys the continuity of the bone trabecula, increases the risk of local bone resorption; the rigid anchor leads to stress that cannot be transmitted to the surrounding bone, accelerating osteoporosis; the standardized anchor position is difficult to match the individualized meniscal attachment point variation.

[0006] The bone cement fixation uses polymethyl methacrylate (PMMA) bone cement to adhere the meniscus prosthesis to the tibial plateau, which has the following disadvantages: the elastic modulus of the bone cement and the bone tissue is not matched, and the interface micro-motion after long-term use leads to loosening; the bone cement cannot promote bone integration, but only relies on mechanical locking; the heat release during the solidification of the bone cement may damage the surrounding tissues.

[0007] In view of the defects in the prior art, the application provides a knee prosthesis fixing device with biomechanical adaptation of a meniscus. SUMMARY

[0008] The purpose of the present invention is to provide a bionic meniscus mechanically adapted knee prosthesis fixation device, which uses a fractal anchor to insert into bone tissue and then expands a shape memory polymer sleeve to achieve non-invasive fixation, thereby solving the problems of stress concentration, high loosening rate and poor motion adaptability existing in traditional meniscus prosthesis fixation.

[0009] To solve the above technical problems, the present invention adopts the following technical solution: a knee joint prosthesis fixation device with bionic meniscus mechanical adaptation, comprising:

[0010] tibia;

[0011] A meniscus prosthesis, wherein the meniscus prosthesis is arranged on the platform of the tibia;

[0012] Fractal porous anchors penetrate the meniscus prosthesis deep into the tibia, securing the meniscus prosthesis to the tibial platform. The fractal porous anchors have a gradient pore structure and can be directly inserted into bone tissue to form a minimally invasive channel without pre-drilling. The gradient pores of the fractal porous anchors promote bone ingrowth, with a bone tissue ingrowth rate of >60% three months after surgery, ultimately achieving biological fixation.

[0013] A shape memory polymer sleeve is wrapped around the middle section of the fractal porous anchor that extends into the tibia. The shape memory polymer sleeve shrinks at low temperatures and has a glass transition temperature of 31-38°C. The shape memory polymer sleeve is in a rigid contracted state at low temperatures and follows the insertion of the fractal porous anchor into the bone tissue. Body temperature triggers the shape memory polymer sleeve to expand due to heat, returning to the designed size and squeezing the surrounding trabeculae outward to form a bone hole that matches the outer diameter of the shape memory polymer sleeve. This process is achieved through elastic deformation rather than destructive drilling, which maximizes the retention of bone density. The radial pressure generated by the expansion provides immediate fixation to avoid micro-movement during surgery.

[0014] The aforementioned bionic meniscus mechanically adapted knee prosthesis fixation device, the fractal porous anchor includes an end portion, an insertion portion and a tip portion, the end portion and the tip portion are respectively arranged at both ends of the insertion portion, the tip portion adopts a tapered thread or a self-tapping tip, the tip portion gently cuts the bone tissue so that the insertion portion extends into the inside of the tibia, the surface of the insertion portion is provided with an inwardly recessed fixing groove, the shape memory polymer sleeve is sleeved in the fixing groove, so that the shape memory polymer sleeve is fixed to the insertion portion.

[0015] The aforementioned bionic meniscus mechanically adapted knee prosthesis fixation device comprises a plurality of fractal porous anchors evenly distributed around the meniscus prosthesis, and the fractal porous anchors are inserted into preset bone hole positions of the tibia.

[0016] The aforementioned bionic meniscus mechanically adapted knee prosthesis fixation device, the meniscus prosthesis includes a surface layer, a middle layer and a bottom layer, and the surface layer, middle layer and bottom layer are fixedly arranged in sequence from top to bottom. The surface layer is made of super-lubricating hydrogel material, which lubricates and reduces friction and wear. The middle layer is made of fiber-reinforced polyethylene material, which provides mechanical support, disperses stress, and absorbs impact energy. The bottom layer is a bracket made of porous titanium alloy, which is bone-integrated and anchored, and achieves long-term stable fixation by bone tissue growing into the pores.

[0017] The aforementioned bionic meniscus mechanically adapted knee prosthesis fixation device has a strip groove opened along the surface of the outer wall of the bottom layer, the end portion of the fractal porous anchor is placed in the strip groove, and the insertion portion is inclined to penetrate the bottom layer and extend into the tibia, so that the insertion portion is inserted into the bone tissue at an angle and is used to accommodate the end portion at the same time. A fixing column is provided on the outside of the strip groove for fixing and suturing the ligament soft tissue. The ligament soft tissue can grow into the porous structure of the bottom porous titanium alloy bracket to achieve long-term stable fixation.

[0018] The aforementioned bionic meniscus mechanically adapted knee prosthesis fixation device, the fractal porous anchor has a gradient pore structure in its insertion portion to achieve bone ingrowth, further realizing a long-term stable fixation structure, and the insertion portion has a diameter of 3-5mm, a length of 20-30mm, and a tip length of 2-8mm to avoid excessive encroachment on bone volume or insufficient fixation strength. A diameter that is too large can easily destroy the integrity of the cortical bone, while a diameter that is too small can result in insufficient anchoring force on the cancellous bone.

[0019] The aforementioned bionic meniscus mechanically adapted knee prosthesis fixation device, the insertion portion of the fractal porous anchor includes an inner core area, a middle transition area, and an outer layer area on the surface. The core area has a pore size of 50-100 μm and a porosity of 70%, providing high-strength support. The transition area has a pore size of 100-200 μm and a porosity of 75%, balancing mechanics and biological functions. The outer layer has a pore size of 200-300 μm and a porosity of 85%, promoting bone tissue ingrowth. The large pores in the outer layer provide migration channels for blood vessels and bone cells, accelerating bone tissue ingrowth, and the small pores in the inner layer absorb blood and growth factors through capillary action, promoting osteoblast attachment and differentiation.

[0020] In the aforementioned bionic meniscus mechanically adapted knee prosthesis fixation device, the outer surface of the shape memory polymer sleeve is provided with micro-protrusions, which form an interference fit with the inner wall of the bone hole after expansion, thereby improving the shear strength.

[0021] In the aforementioned bionic meniscus mechanically adapted knee prosthesis fixation device, the shape memory polymer sleeve has a wall thickness of 0.5-1 mm, a diameter in the low-temperature contracted state that is less than 90% of the diameter of the insertion portion, and a radial expansion rate of 12%-15% after glass transition.

[0022] The aforementioned bionic meniscus mechanically adapted knee prosthesis fixation device, the fractal porous anchor is made of titanium alloy 3D printing, and the surface is coated with nano-hydroxyapatite coating to promote bone integration, increase the contact area between bone tissue and coating, and improve shear strength. The hydroxyl groups in hydroxyapatite form hydrogen bonds with collagen, strengthening biological bonding and inhibiting inflammatory responses.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] (1) The present invention enhances bone integration and stability by using fractal porous anchors combined with nano-hydroxyapatite coating. Three months after surgery, the bone ingrowth rate is >60% and the pull-out resistance is >1200N.

[0025] (2) The present invention uses fractal porous anchors combined with shape memory polymer sleeves for fixation, avoiding the drilling damage of traditional anchors and reducing bone loss. The porous structure allows bone tissue to grow in and transmit stress, reducing the stress shielding effect. After the sleeve expands, the interface shear strength far exceeds that of traditional anchors.

[0026] (3) The meniscus prosthesis of the present invention adopts three layers of gradient materials, namely, a surface layer of super-lubricating hydrogel, a middle layer of fiber-reinforced polyethylene, and a bottom layer of porous titanium alloy. The connection between each layer takes into account mechanical strength, interface stability and biocompatibility. The surface layer is responsible for lubrication, reducing joint friction and extending the life of the prosthesis; the middle layer is responsible for mechanical buffering, evenly transferring the load to the bottom layer; the bottom layer achieves biological fixation through bone ingrowth, ensuring long-term stability, simulating the mechanical and biological functions of the natural meniscus, and systematically solving the problems of wear, loosening and poor adaptability of traditional prostheses. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the installation structure of the meniscus prosthesis of the present invention;

[0028] Figure 2 is a cross-sectional view of the meniscus prosthesis installation structure of the present invention;

[0029] Figure 3 This is a schematic diagram of the fractal porous anchor structure of the present invention;

[0030] Figure 4 It is a schematic diagram of the gradient pore structure of the fractal porous anchor of the present invention.

[0031] Figure numerals: 1-tibia, 2-meniscus prosthesis, 201-surface layer, 202-middle layer, 203-bottom layer, 204-strip groove, 205-fixation column, 3-fractal porous anchor, 301-end head, 302-insertion part, 303-tip part, 304-fixation groove, 4-shape memory polymer sleeve.

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0033] Embodiment 1 of the present invention: A bionic meniscus mechanically adapted knee prosthesis fixation device, comprising: a tibia 1, a meniscus prosthesis 2, a fractal porous anchor 3, and a shape memory polymer sleeve 4, wherein the meniscus prosthesis 2 is arranged on the platform of the tibia 1, and the fractal porous anchor 3 penetrates the meniscus prosthesis 2 and penetrates into the interior of the tibia 1, so that the meniscus prosthesis 2 is fixed to the tibia 1 platform. The fractal porous anchor 3 has a gradient pore structure and can be directly inserted into the bone tissue to form a minimally invasive channel without pre-drilling. The gradient pores of the fractal porous anchor 3 promote bone ingrowth. The bone tissue ingrowth rate is greater than 60% 3 months after surgery, and biological fixation is finally formed. The shape memory polymer sleeve 4 is wrapped around the middle section of the fractal porous anchor 3 extending into the tibia 1. The shape memory polymer sleeve 4 shrinks at low temperatures and its glass transition temperature is 31-38°C. The shape memory polymer sleeve 4 is in a rigid contracted state at low temperatures. Following the insertion of the fractal porous anchor 3 into the bone tissue, the body temperature (around 37°C) triggers the shape memory polymer sleeve 4 to expand due to heat, restore to the designed size, and squeeze the surrounding trabeculae outward to form a bone hole that matches the outer diameter of the shape memory polymer sleeve 4. This process is achieved through elastic deformation rather than destructive drilling, which maximizes the retention of bone density. The radial pressure generated by the expansion provides immediate fixation to avoid micro-movement during surgery.

[0034] Embodiment 2 of the present invention: A bionic meniscus mechanically adapted knee prosthesis fixation device, comprising: a tibia 1, a meniscus prosthesis 2, a fractal porous anchor 3, and a shape memory polymer sleeve 4, wherein the meniscus prosthesis 2 is arranged on the platform of the tibia 1, and the fractal porous anchor 3 penetrates the meniscus prosthesis 2 and penetrates into the interior of the tibia 1, so that the meniscus prosthesis 2 is fixed to the tibia 1 platform. The fractal porous anchor 3 has a gradient pore structure and can be directly inserted into the bone tissue to form a minimally invasive channel without pre-drilling. The gradient pores of the fractal porous anchor 3 promote bone ingrowth. The bone tissue ingrowth rate is greater than 60% 3 months after surgery, and biological fixation is finally formed. The shape memory polymer sleeve 4 is wrapped around the middle section of the fractal porous anchor 3 extending into the tibia 1. The shape memory polymer sleeve 4 shrinks at low temperatures and its glass transition temperature is 31-38°C. The shape memory polymer sleeve 4 is in a rigid contracted state at low temperatures. Following the insertion of the fractal porous anchor 3 into the bone tissue, the body temperature (around 37°C) triggers the shape memory polymer sleeve 4 to expand due to heat, restore to the designed size, and squeeze the surrounding trabeculae outward to form a bone hole that matches the outer diameter of the shape memory polymer sleeve 4. This process is achieved through elastic deformation rather than destructive drilling, which maximizes the retention of bone density. The radial pressure generated by the expansion provides immediate fixation to avoid micro-movement during surgery.

[0035] The fractal porous anchor 3 includes an end portion 301, an insertion portion 302 and a tip portion 303, wherein the end portion 301 and the tip portion 303 are respectively arranged at both ends of the insertion portion 302, and the tip portion 303 adopts a tapered thread or a self-tapping tip. The tip portion 303 gently cuts the bone tissue so that the insertion portion 302 extends into the interior of the tibia 1. The surface of the insertion portion 302 is provided with an inwardly recessed fixing groove 304, and the shape memory polymer sleeve 4 is sleeved in the fixing groove 304 to fix the shape memory polymer sleeve 4 to the insertion portion 302; the insertion portion 302 of the fractal porous anchor 3 adopts a gradient pore structure to achieve bone ingrowth and further realize a long-term stable fixation structure, and the insertion portion 302 has a diameter of 3 mm and a length of 20 mm, and the tip portion 303 has a length of 8 mm to avoid excessive encroachment on bone volume or insufficient fixation strength. A diameter that is too large can easily damage the integrity of the cortical bone, while a diameter that is too small can lead to insufficient anchoring force in the cancellous bone. Among them, the insertion portion 302 of the fractal porous anchor 3 includes an inner core area, a middle transition area, and an outer layer area on the surface. The core area has a pore size of 50-100 μm and a porosity of 70%, providing high-strength support. The transition area has a pore size of 100-200 μm and a porosity of 75%, balancing mechanical and biological functions. The outer layer has a pore size of 200-300 μm and a porosity of 85%, promoting bone tissue ingrowth; the large pores in the outer layer provide migration channels for blood vessels and bone cells, accelerating bone tissue ingrowth, and the small pores in the inner layer absorb blood and growth factors through capillary action, promoting osteoblast attachment and differentiation.

[0036] The normal adult tibial plateau width is 60-80 mm, and the diameter of the meniscus attachment area ranges from 3-6 mm. The anchor diameter must match the anatomy of the attachment area to avoid excessive bone encroachment or insufficient fixation strength. The cortical bone thickness of the tibial plateau is approximately 1-3 mm, and the cancellous bone porosity is 50%-90%. A diameter of the insertion portion 302 that is too large can easily damage the integrity of the cortical bone, while a diameter that is too small can result in insufficient cancellous bone anchoring. During knee joint motion, the meniscus prosthesis must withstand cyclical tensile forces of 200-500 N, and the anchor pullout resistance must be >800 N. Experimental results show that a 4 mm diameter titanium alloy anchor can achieve a pullout resistance of 1200 N in cancellous bone. A 3.0 mm diameter is suitable for patients with osteoporosis or revision surgery to reduce bone loss.

[0037] Specifically, the fractal porous anchor 3 is made of titanium alloy 3D printing, and the surface is coated with nano-hydroxyapatite coating to promote bone integration, increase the contact area between bone tissue and the coating, and improve shear strength. The hydroxyl groups in hydroxyapatite form hydrogen bonds with collagen, strengthening biological bonding and inhibiting inflammatory response; and the fractal porous anchor 3 is provided in plurality and evenly distributed around the meniscus prosthesis 2, and the fractal porous anchor 3 is inserted into the preset bone hole position of the tibia 1.

[0038] The meniscus prosthesis 2 includes a surface layer 201, a middle layer 202 and a bottom layer 203, and the surface layer 201, the middle layer 202 and the bottom layer 203 are fixedly arranged in sequence from top to bottom. The surface layer 201 is made of a super-lubricating hydrogel material, which lubricates and reduces friction and wear. The middle layer 202 is made of a fiber-reinforced polyethylene material, which provides mechanical support, disperses stress, and absorbs impact energy. The bottom layer 203 is a bracket made of a porous titanium alloy, which is bone-integrated and anchored, and achieves long-term stable fixation through bone tissue growing into the pores. A strip groove 204 is provided along the surface of the outer wall of 203, and the end portion 301 of the fractal porous anchor 3 is placed in the strip groove 204, and the insertion portion 302 is arranged obliquely to penetrate the bottom layer 203 and extend into the tibia 1, so that the insertion portion 302 is inserted into the bone tissue at an angle, and is used to accommodate the end portion 301, and a fixing column 205 is provided on the outside of the strip groove 204 for fixing and suturing the ligament soft tissue. The ligament soft tissue can grow into the porous structure of the porous titanium alloy bracket of the bottom layer 203 to achieve long-term stable fixation.

[0039] The wall thickness of the shape memory polymer sleeve 4 is 0.5 mm, and its diameter in the low-temperature contraction state is less than 90% of the diameter of the insertion portion 302. The radial expansion rate after glass transition is 12%. The outer surface of the shape memory polymer sleeve 4 is provided with micro-protrusions, which form an interference fit with the inner wall of the bone hole after expansion to improve the shear strength.

[0040] Embodiment 3 of the present invention: A bionic meniscus mechanically adapted knee prosthesis fixation device, comprising: a tibia 1, a meniscus prosthesis 2, a fractal porous anchor 3, and a shape memory polymer sleeve 4, wherein the meniscus prosthesis 2 is arranged on the platform of the tibia 1, and the fractal porous anchor 3 penetrates the meniscus prosthesis 2 and penetrates into the interior of the tibia 1, so that the meniscus prosthesis 2 is fixed to the tibia 1 platform. The fractal porous anchor 3 has a gradient pore structure and can be directly inserted into the bone tissue to form a minimally invasive channel without pre-drilling. The gradient pores of the fractal porous anchor 3 promote bone ingrowth. The bone tissue ingrowth rate is greater than 60% 3 months after surgery, and biological fixation is finally formed. The shape memory polymer sleeve 4 is wrapped around the middle section of the fractal porous anchor 3 extending into the tibia 1. The shape memory polymer sleeve 4 shrinks at low temperatures and its glass transition temperature is 31-38°C. The shape memory polymer sleeve 4 is in a rigid contracted state at low temperatures. Following the insertion of the fractal porous anchor 3 into the bone tissue, the body temperature (around 37°C) triggers the shape memory polymer sleeve 4 to expand due to heat, restore to the designed size, and squeeze the surrounding trabeculae outward to form a bone hole that matches the outer diameter of the shape memory polymer sleeve 4. This process is achieved through elastic deformation rather than destructive drilling, which maximizes the retention of bone density. The radial pressure generated by the expansion provides immediate fixation to avoid micro-movement during surgery.

[0041] The fractal porous anchor 3 includes an end portion 301, an insertion portion 302 and a tip portion 303, wherein the end portion 301 and the tip portion 303 are respectively arranged at both ends of the insertion portion 302, and the tip portion 303 adopts a tapered thread or a self-tapping tip. The tip portion 303 gently cuts the bone tissue so that the insertion portion 302 extends into the interior of the tibia 1. The surface of the insertion portion 302 is provided with an inwardly recessed fixing groove 304, and the shape memory polymer sleeve 4 is sleeved in the fixing groove 304 to fix the shape memory polymer sleeve 4 to the insertion portion 302; the insertion portion 302 of the fractal porous anchor 3 adopts a gradient pore structure to achieve bone ingrowth and further realize a long-term stable fixation structure, and the insertion portion 302 has a diameter of 5 mm and a length of 30 mm, and the tip portion 303 has a length of 2 mm to avoid excessive encroachment on bone volume or insufficient fixation strength. If the diameter is too large, it is easy to damage the integrity of the cortical bone, and if it is too small, the cancellous bone anchoring force is insufficient. Among them, the insertion portion 302 of the fractal porous anchor 3 includes an inner core area, a middle transition area, and an outer layer area on the surface. The core area has a pore size of 50-100 μm and a porosity of 70%, providing high-strength support. The transition area has a pore size of 100-200 μm and a porosity of 75%, balancing mechanical and biological functions. The outer layer has a pore size of 200-300 μm and a porosity of 85%, promoting bone tissue ingrowth; the large pores in the outer layer provide migration channels for blood vessels and bone cells, accelerating bone tissue ingrowth, and the small pores in the inner layer absorb blood and growth factors through capillary action, promoting osteoblast attachment and differentiation.

[0042] The normal adult tibial plateau width is 60-80 mm, and the diameter of the anterior / posterior meniscus attachment area ranges from 3-6 mm. The anchor diameter must match the anatomy of the attachment area to avoid excessive bone encroachment or insufficient fixation strength. The cortical bone thickness of the tibial plateau is approximately 1-3 mm, and the cancellous bone porosity is 50%-90%. A diameter of the insertion portion 302 that is too large can easily damage the integrity of the cortical bone, while a diameter that is too small can result in insufficient cancellous bone anchoring. During knee joint motion, the meniscus prosthesis must withstand cyclic tensile forces of 200-500 N, and the anchor pullout resistance must be >800 N. Experimental results show that a 4 mm diameter titanium alloy anchor can achieve a pullout resistance of 1200 N in cancellous bone. A 5.0 mm diameter is suitable for patients with high mobility or excellent bone density.

[0043] Specifically, the fractal porous anchor 3 is made of titanium alloy 3D printing, and the surface is coated with nano-hydroxyapatite coating to promote bone integration, increase the contact area between bone tissue and the coating, and improve shear strength. The hydroxyl groups in hydroxyapatite form hydrogen bonds with collagen, strengthening biological bonding and inhibiting inflammatory response; and the fractal porous anchor 3 is provided in plurality and evenly distributed around the meniscus prosthesis 2, and the fractal porous anchor 3 is inserted into the preset bone hole position of the tibia 1.

[0044] The meniscus prosthesis 2 includes a surface layer 201, a middle layer 202 and a bottom layer 203, and the surface layer 201, the middle layer 202 and the bottom layer 203 are fixedly arranged in sequence from top to bottom. The surface layer 201 is made of a super-lubricating hydrogel material, which lubricates and reduces friction and wear. The middle layer 202 is made of a fiber-reinforced polyethylene material, which provides mechanical support, disperses stress, and absorbs impact energy. The bottom layer 203 is a bracket made of a porous titanium alloy, which is bone-integrated and anchored, and achieves long-term stable fixation through bone tissue growing into the pores. A strip groove 204 is provided along the surface of the outer wall of 203, and the end portion 301 of the fractal porous anchor 3 is placed in the strip groove 204, and the insertion portion 302 is arranged obliquely to penetrate the bottom layer 203 and extend into the tibia 1, so that the insertion portion 302 is inserted into the bone tissue at an angle, and is used to accommodate the end portion 301, and a fixing column 205 is provided on the outside of the strip groove 204 for fixing and suturing the ligament soft tissue. The ligament soft tissue can grow into the porous structure of the porous titanium alloy bracket of the bottom layer 203 to achieve long-term stable fixation.

[0045] The wall thickness of the shape memory polymer sleeve 4 is 1 mm, and its diameter in the low-temperature contraction state is less than 90% of the diameter of the insertion portion 302. The radial expansion rate after glass transition is 15%. The outer surface of the shape memory polymer sleeve 4 is provided with micro-protrusions, which form an interference fit with the inner wall of the bone hole after expansion to improve the shear strength.

[0046] Embodiment 4 of the present invention: A bionic meniscus mechanically adapted knee prosthesis fixation device, comprising: a tibia 1, a meniscus prosthesis 2, a fractal porous anchor 3, and a shape memory polymer sleeve 4, wherein the meniscus prosthesis 2 is arranged on the platform of the tibia 1, and the fractal porous anchor 3 penetrates the meniscus prosthesis 2 and penetrates into the interior of the tibia 1, so that the meniscus prosthesis 2 is fixed to the tibia 1 platform. The fractal porous anchor 3 has a gradient pore structure and can be directly inserted into the bone tissue to form a minimally invasive channel without pre-drilling. The gradient pores of the fractal porous anchor 3 promote bone ingrowth. The bone tissue ingrowth rate is greater than 60% 3 months after surgery, and biological fixation is finally formed. The shape memory polymer sleeve 4 is wrapped around the middle section of the fractal porous anchor 3 extending into the tibia 1. The shape memory polymer sleeve 4 shrinks at low temperatures and its glass transition temperature is 31-38°C. The shape memory polymer sleeve 4 is in a rigid contracted state at low temperatures. Following the insertion of the fractal porous anchor 3 into the bone tissue, the body temperature (around 37°C) triggers the shape memory polymer sleeve 4 to expand due to heat, restore to the designed size, and squeeze the surrounding trabeculae outward to form a bone hole that matches the outer diameter of the shape memory polymer sleeve 4. This process is achieved through elastic deformation rather than destructive drilling, which maximizes the retention of bone density. The radial pressure generated by the expansion provides immediate fixation to avoid micro-movement during surgery.

[0047] The fractal porous anchor 3 includes an end portion 301, an insertion portion 302 and a tip portion 303, wherein the end portion 301 and the tip portion 303 are respectively arranged at both ends of the insertion portion 302, and the tip portion 303 adopts a tapered thread or a self-tapping tip. The tip portion 303 gently cuts the bone tissue so that the insertion portion 302 extends into the interior of the tibia 1. The surface of the insertion portion 302 is provided with an inwardly recessed fixing groove 304, and the shape memory polymer sleeve 4 is sleeved in the fixing groove 304 to fix the shape memory polymer sleeve 4 to the insertion portion 302; the insertion portion 302 of the fractal porous anchor 3 adopts a gradient pore structure to achieve bone ingrowth and further realize a long-term stable fixation structure, and the insertion portion 302 has a diameter of 4mm and a length of 20-30mm, and the tip portion 303 is 5mm long to avoid excessive encroachment on bone volume or insufficient fixation strength. A diameter that is too large can easily damage the integrity of the cortical bone, while a diameter that is too small can lead to insufficient anchoring force in the cancellous bone. Among them, the insertion portion 302 of the fractal porous anchor 3 includes an inner core area, a middle transition area, and an outer layer area on the surface. The core area has a pore size of 50-100 μm and a porosity of 70%, providing high-strength support. The transition area has a pore size of 100-200 μm and a porosity of 75%, balancing mechanical and biological functions. The outer layer has a pore size of 200-300 μm and a porosity of 85%, promoting bone tissue ingrowth; the large pores in the outer layer provide migration channels for blood vessels and bone cells, accelerating bone tissue ingrowth, and the small pores in the inner layer absorb blood and growth factors through capillary action, promoting osteoblast attachment and differentiation.

[0048] The normal adult tibial plateau width is 60-80mm, and the diameter of the meniscus attachment area ranges from 3-6mm. The anchor diameter must match the anatomy of the attachment area to avoid excessive bone encroachment or insufficient fixation strength. The tibial plateau cortical bone thickness is approximately 1-3mm, and the cancellous bone porosity is 50%-90%. An excessively large diameter of the insertion portion 302 can easily damage the integrity of the cortical bone, while a too small diameter can result in insufficient cancellous bone anchoring. During knee joint motion, the meniscus prosthesis must withstand cyclic tensile forces of 200-500N, and the anchor pullout resistance must be greater than 800N. Experimental results show that a 4mm diameter titanium alloy anchor can achieve a pullout resistance of 1200N in cancellous bone. 4.0mm is a standard size, balancing strength and biointegration efficiency.

[0049] Specifically, the fractal porous anchor 3 is made of titanium alloy 3D printing, and the surface is coated with nano-hydroxyapatite coating to promote bone integration, increase the contact area between bone tissue and the coating, and improve shear strength. The hydroxyl groups in hydroxyapatite form hydrogen bonds with collagen, strengthening biological bonding and inhibiting inflammatory response; and the fractal porous anchor 3 is provided in plurality and evenly distributed around the meniscus prosthesis 2, and the fractal porous anchor 3 is inserted into the preset bone hole position of the tibia 1.

[0050] The meniscus prosthesis 2 includes a surface layer 201, a middle layer 202 and a bottom layer 203, and the surface layer 201, the middle layer 202 and the bottom layer 203 are fixedly arranged in sequence from top to bottom. The surface layer 201 is made of a super-lubricating hydrogel material, which lubricates and reduces friction and wear. The middle layer 202 is made of a fiber-reinforced polyethylene material, which provides mechanical support, disperses stress, and absorbs impact energy. The bottom layer 203 is a bracket made of a porous titanium alloy, which is bone-integrated and anchored, and achieves long-term stable fixation through bone tissue growing into the pores. A strip groove 204 is provided along the surface of the outer wall of 203, and the end portion 301 of the fractal porous anchor 3 is placed in the strip groove 204, and the insertion portion 302 is arranged obliquely to penetrate the bottom layer 203 and extend into the tibia 1, so that the insertion portion 302 is inserted into the bone tissue at an angle, and is used to accommodate the end portion 301, and a fixing column 205 is provided on the outside of the strip groove 204 for fixing and suturing the ligament soft tissue. The ligament soft tissue can grow into the porous structure of the porous titanium alloy bracket of the bottom layer 203 to achieve long-term stable fixation.

[0051] The connection between the surface layer and the middle layer of the meniscus prosthesis 2 is achieved by plasma-activating the polyethylene surface to form a covalent bond with the hydrogel. The polyethylene surface is laser-engraved with micropores, which are filled with hydrogel to form mechanical anchors, ensuring a seamless transition between the lubrication layer and the support layer and preventing delamination under dynamic loads. The connection between the middle layer and the bottom layer improves the penetration of polyethylene melt into the pores of the titanium alloy at high temperatures, forming a "pinning effect" to achieve a mechanical gradient transition between the flexible support layer and the rigid bone integration layer, reducing stress concentration.

[0052] The wall thickness of the shape memory polymer sleeve 4 is 0.7 mm, and its diameter in the low-temperature contraction state is less than 90% of the diameter of the insertion portion 302. The radial expansion rate after glass transition is 13%. The outer surface of the shape memory polymer sleeve 4 is provided with micro-protrusions, which form an interference fit with the inner wall of the bone hole after expansion to improve the shear strength.

[0053] The working principle of an embodiment of the present invention: The present invention includes the following process during use:

[0054] Preoperative planning and customization: CT / MRI is used to obtain three-dimensional data of the patient's tibial plateau and reconstruct the bone density distribution map; fractal pore parameters are optimized based on the bone density distribution, and the sleeve expansion rate is customized according to the bone pore diameter (measured by imaging).

[0055] The intraoperative procedure involves soaking the anchor-sleeve assembly in 4°C saline for 15 minutes to shrink the sleeve to its minimum diameter. The anchor is inserted into the pre-set position (no drilling required), and a guide is used to ensure axial alignment. Five to 10 minutes after implantation, the sleeve expands at body temperature, and the surgeon uses a torque wrench to test the fixation strength.

[0056] Postoperative monitoring and evaluation: Anchor position was verified by X-ray at 1 week after surgery; bone ingrowth rate and pore filling degree were evaluated by Micro-CT at 3 / 6 / 12 months after surgery; and changes in interface stiffness were monitored by vibration frequency analysis (VFA) to ensure normal bone integration.

Claims

1. A bionic meniscus mechanically adapted knee joint prosthesis fixation device, characterized in that: include: tibia (1); A meniscus prosthesis (2), wherein the meniscus prosthesis (2) is arranged on a platform of the tibia (1); A fractal porous anchor (3) is provided, wherein the fractal porous anchor (3) penetrates the meniscus prosthesis (2) and penetrates into the interior of the tibia (1), thereby fixing the meniscus prosthesis (2) on the tibia (1) platform, and the fractal porous anchor (3) has a gradient pore structure; and a shape memory polymer sleeve (4), wherein the shape memory polymer sleeve (4) is wrapped around the middle section of the fractal porous anchor (3) extending into the tibia (1), and the shape memory polymer sleeve (4) shrinks at low temperature and has a glass transition temperature of 31-38°C.

2. The bionic meniscus mechanically adapted knee joint prosthesis fixation device according to claim 1, characterized in that: The fractal porous anchor (3) comprises an end portion (301), an insertion portion (302) and a tip portion (303), wherein the end portion (301) and the tip portion (303) are respectively arranged at both ends of the insertion portion (302), and the tip portion (303) adopts a tapered thread or a self-tapping tip, and the tip portion (303) gently cuts the bone tissue so that the insertion portion (302) is inserted into the interior of the tibia (1). The surface of the insertion portion (302) is provided with an inwardly recessed fixing groove (304), and the shape memory polymer sleeve (4) is sleeved in the fixing groove (304).

3. A bionic meniscus mechanically adapted knee joint prosthesis fixation device according to claim 1 or 2, characterized in that: The fractal porous anchors (3) are provided in plurality and are evenly distributed around the meniscus prosthesis (2), and the fractal porous anchors (3) are inserted into the preset bone hole positions of the tibia (1).

4. The bionic meniscus mechanically adapted knee joint prosthesis fixation device according to claim 2, characterized in that: The meniscus prosthesis (2) comprises a surface layer (201), a middle layer (202) and a bottom layer (203), and the surface layer (201), the middle layer (202) and the bottom layer (203) are fixedly arranged in sequence from top to bottom, the surface layer (201) is made of a super-lubricating hydrogel material, the middle layer (202) is made of a fiber-reinforced polyethylene material, and the bottom layer (203) is a bracket made of a porous titanium alloy.

5. The bionic meniscus mechanically adapted knee joint prosthesis fixation device according to claim 4, characterized in that: A strip groove (204) is provided along the surface of the outer wall of the bottom layer (203); the end portion (301) of the fractal porous anchor (3) is placed in the strip groove (204); the insertion portion (302) is arranged obliquely to pass through the bottom layer (203) and extend into the tibia (1); and a fixing column (205) is provided on the outer side of the strip groove (204).

6. A bionic meniscus mechanically adapted knee joint prosthesis fixation device according to claim 2 or 5, characterized in that: The insertion portion (302) of the fractal porous anchor (3) adopts a gradient pore structure, and the insertion portion (302) has a diameter of 3-5 mm, a length of 20-30 mm, and a tip portion (303) of 2-8 mm in length.

7. The bionic meniscus mechanically adapted knee joint prosthesis fixation device according to claim 6, characterized in that: The insertion portion (302) of the fractal porous anchor (3) comprises an inner core region, a middle transition region, and an outer layer region. The core region has a pore size of 50-100 μm and a porosity of 70%, the transition region has a pore size of 100-200 μm and a porosity of 75%, and the outer layer region has a pore size of 200-300 μm and a porosity of 85%.

8. The bionic meniscus mechanically adapted knee joint prosthesis fixation device according to claim 7, characterized in that: The outer surface of the shape memory polymer sleeve (4) is provided with micro-protrusions.

9. The bionic meniscus mechanically adapted knee joint prosthesis fixation device according to claim 8, characterized in that: The shape memory polymer sleeve (4) has a wall thickness of 0.5-1 mm, a diameter in a low-temperature contraction state that is less than 90% of the diameter of the insertion portion (302), and a radial expansion rate of 12%-15% after glass transition.

10. The bionic meniscus mechanically adapted knee joint prosthesis fixation device according to claim 1, characterized in that: The fractal porous anchor (3) is made by 3D printing of titanium alloy, and the surface is coated with a nano-hydroxyapatite coating.

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