A posterior cruciate ligament reconstruction 3D printing guide plate positioning system and method

Abstract

The application provides a 3D printing guide plate positioning system and method for posterior cruciate ligament reconstruction, and belongs to the technical field of ligament surgical instruments in sports medicine. The system comprises a positioning guide plate, a guide plate supporting frame and a drilling guide arm. The positioning guide plate is shaped according to a three-dimensional reconstruction model of a tibia, is manufactured through 3D printing, and is connected to the guide plate supporting frame. One side of the positioning guide plate is attached with a flexible sensor to detect the attached stress. The drilling guide arm is fixedly connected to the guide plate supporting frame after the positioning guide plate is placed at a set position to realize the positioning of drilling. The method is realized based on the system. Through the positioning system, the influence of human factors in surgery is reduced, the establishment of the tibial tunnel is more scientific and accurate by combining with the sensing technology, the problems of possible reconstruction and healing failure, bone damage and the like are solved, and the recovery of the movement ability of the patient is accelerated.

Description

Technical Field

[0001] The present invention relates to the technical field of sports medicine ligament surgical instruments, and in particular to a 3D printing guide positioning system and method for posterior cruciate ligament reconstruction. Background Art

[0002] The posterior cruciate ligament (PCL) is a powerful ligament that maintains the stability of the posterior knee joint and serves as the movement center of the knee joint. PCL injury is difficult to heal on its own, which can worsen knee degeneration in the long term and increase the risk of knee osteoarthritis. With advances in arthroscopic PCL reconstruction technology, surgical treatment has become the primary treatment. Reconstruction of PCL injuries using all-in-one techniques has developed rapidly in recent years, becoming more minimally invasive and refined. In particular, it effectively overcomes the problems of traditional reconstruction, such as cumbersome procedures, "killer turns," high tendon requirements, and extensive bone damage.

[0003] In clinical practice, the establishment of the tibial tunnel for the posterior cruciate ligament relies heavily on the surgeon's clinical experience, with low repeatability and poor precision. Once the tibial tunnel is established incorrectly, it is difficult to change it. Long-term immobilization is required after surgery, which leads to delayed knee joint rehabilitation and poor recovery of knee joint function, thus causing deviations in surgical efficacy.

[0004] The technical problem to be solved by the present invention is how to accurately position, fit the bone surface, and avoid the "killer corner" during posterior cruciate ligament reconstruction surgery. Summary of the Invention

[0005] The purpose of the present invention is to provide a 3D printing guide positioning system and method for posterior cruciate ligament reconstruction.

[0006] In order to solve the above-mentioned technical problems, the purpose of the present invention is achieved as follows:

[0007] A 3D printing guide positioning system for posterior cruciate ligament reconstruction, comprising: a positioning guide, a guide support frame, a drilling guide arm, a tibial top support rod, a tibial fixation cable, and a signal processing and display unit;

[0008] The positioning guide is obtained by three-dimensional reconstruction of the tibia and is manufactured by 3D printing technology; a flexible sensor is provided on the side of the positioning guide that is in contact with the bone surface; a tibial bone tunnel drilling avoidance hole is opened through the middle of the positioning guide and the flexible sensor;

[0009] The guide plate support frame comprises a support rod and a support foot; the support rod is fixed on the top of the support foot, the first end of the support rod is connected with the positioning guide plate; a connecting seat is arranged in the middle of the support rod, and a sliding rod is formed from the connecting seat to the second end of the support rod; a buckle groove is arranged on the connecting seat;

[0010] A sliding sleeve is arranged on the top of the drill guide arm, and a tibial tunnel positioning hole is arranged on the bottom of the drill guide arm; the sliding sleeve is matched with the sliding rod, and a plurality of buckles matched with the buckle groove are arranged on the sliding sleeve;

[0011] A threaded hole is arranged in the middle of the support foot, and the threaded hole is threadedly matched with the tibial support rod; a cable connecting hole is arranged on the first end of the tibial support rod, and a rotating handle is arranged on the second end of the tibial support rod;

[0012] The tibial fixing cable is connected to the cable connecting hole and is annularly arranged on the lower leg of the patient;

[0013] The signal processing and display unit is used for processing the stress signal detected by the flexible sensor and displaying stress information and information about the adhesion of the positioning guide plate to the bone surface.

[0014] In the above scheme and as a preferred scheme of the above scheme, the material of the positioning guide plate is composed of thermoplastic polyurethane and polycaprolactone.

[0015] In the above scheme and as a preferred scheme of the above scheme, the flexible sensor adopts a five-layer structure, the uppermost layer and the lowermost layer adopt PET film as an encapsulation layer, the middle layer adopts a dielectric layer composed of polystyrene microspheres, graphene and PDMS film, and the dielectric layer is attached with an activated carbon non-woven fabric electrode layer on the upper and lower sides, thereby constituting a capacitive pressure sensor.

[0016] In the above scheme and as a preferred scheme of the above scheme, a limiting protrusion is arranged on the sliding rod; a positioning groove matched with the limiting protrusion is arranged in the sliding sleeve.

[0017] In the above scheme and as a preferred scheme of the above scheme, the tibial fixing cable is woven by a plurality of silk threads and is a cylindrical or strip-shaped cable.

[0018] On the basis of the above scheme and as a preferred scheme of the above scheme, the signal processing and display unit includes an AD conversion unit, an MCU processor, a battery and a screen; the AD conversion unit is used to collect the stress signal detected by the flexible sensor; the MCU processor is used for data sampling, original digital signal filtering, stress information calculation, fit calculation, power management and display processing; the battery supplies power to the entire unit; the screen is used to display stress information and information on the fit between the positioning guide and the bone surface, and the screen is detachable and fixed on the sliding rod.

[0019] A 3D printed guide positioning method for posterior cruciate ligament reconstruction comprises the following steps:

[0020] S1. Perform three-dimensional reconstruction of the tibia using preoperative MRI or CT imaging, and confirm the position of the tibial stump of the posterior cruciate ligament to obtain the tibial insertion point. Determine the tibial bone tunnel through preoperative anteromedial tibial positioning point planning and perform simulation to avoid the influence of the "killer turn";

[0021] S2. Using the 3D tibial model, the bone surface of the tibial insertion point is extracted to establish an accurate surgical positioning guide model, which is then manufactured using 3D printing technology.

[0022] S3, fixing the prepared positioning guide plate to the first end of the support rod of the guide plate support frame, and attaching the flexible sensor to one side of the positioning guide plate;

[0023] S4. Move the guide plate support frame to the side of the patient's leg, place the positioning guide plate near the tibial insertion point, and measure the stress distribution between the positioning guide plate and the tibia using the flexible sensor on the positioning guide plate. The signal processing unit processes the stress value distribution cloud map and force value standard deviation, which are displayed on the display unit.

[0024] S5. Adjust the position of the positioning guide plate by using the cloud diagram displayed on the display unit so that the force standard deviation is below the set value, and determine that the positioning guide plate is in the correct position at this time;

[0025] S6. Move the drilling guide arm and fix it to the guide plate support frame (2) through a buckle, so that the tibial bone tunnel positioning hole at the bottom is fixed on one side of the tibia to achieve drilling positioning.

[0026] On the basis of the above scheme and as a preferred scheme of the above scheme, the material of the positioning guide plate is composed of thermoplastic polyurethane (TPU) and polycaprolactone (PCL); its manufacturing method comprises the following steps: drying TPU and PCL in 80 DEG C and 50 DEG C ovens respectively for 24 hours, then configuring the component ratio of 80% TPU and 20% PCL to make a composition; putting the composition into an extruder, while setting the temperature of the temperature control zone of the extruder barrel to 180-190 DEG C, the screw rotation speed to 25 r / min, and melting extruding; cooling the extruded melt blend in cooling water to form a pellet; drying the pellet in a vacuum oven at 50 DEG C for 24 hours to remove moisture, and then using an injection molding machine to perform injection molding, and sending the raw material obtained by injection molding to the discharge port of a 3D printer to perform 3D printing.

[0027] On the basis of the above scheme and as a preferred scheme of the above scheme, the flexible sensor adopts a five-layer structure, and from top to bottom, the five-layer structure comprises, in sequence, a PET film packaging layer, an activated carbon non-woven fabric electrode layer, polystyrene microspheres, a graphene and PDMS film dielectric layer, an activated carbon non-woven fabric electrode layer and a PET film packaging layer; the preparation process of the dielectric layer comprises the following steps: 1, uniformly dropping photoresist on a cleaned silicon wafer, and then using an automatic photoresist coating machine to spin coat the photoresist at a rotation speed of 3000 r / min for 1 minute to ensure that the photoresist uniformly and smoothly covers the surface of the silicon wafer; 2, baking the silicon wafer on a baking table at 100 DEG C for 2 minutes to obtain a surface flat photoresist sacrificial layer; 3, slowly stacking the mixed emulsion of graphene and polystyrene microspheres on the silicon wafer on which the sacrificial layer is laid by drop casting, and standing until the solution volatilizes; 4, mixing the PDMS prepolymer and the curing agent according to a mass ratio of 10:1, stirring for 10 min, and then standing for 30 min to remove the liquid surface bubbles; 5, pouring the prepared PDMS mixed solution on the substrate on which the graphene and polystyrene microsphere layer is stacked, using a photoresist coating machine to spin coat the PDMS mixed solution at a rotation speed of 500 r / min for 1 minute, and then standing for 2 hours; 6, placing the silicon wafer on which the PDMS mixed solution is spin coated on a baking table at a temperature of 75 DEG C, and heating for 2 hours to solidify the film; 7, placing the solidified PDMS substrate in an acetone solution, completely peeling off the film from the silicon wafer, and then washing the film in deionized water to remove the solution attached to the film to obtain the required ultra-thin graphene, polystyrene microsphere and PDMS composite dielectric layer film; and 8, die cutting the dielectric layer film to form a plurality of small circular sensing micro units, and attaching the small circular sensing micro units to the activated carbon non-woven fabric electrode layer.

[0028] The beneficial effects of the present application are:

[0029] Through the positioning system, the influence of human factors in surgery is reduced, the establishment of the tibial tunnel is more scientific and accurate by combining with sensing technology, the problems of possible reconstruction and healing failure, bone damage and the like are solved, and the recovery of the patient's motor ability is accelerated. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the positioning system of the present invention connected to the tibia structure.

[0031] Figure 2 Schematic diagram of the positioning system structure of the present invention.

[0032] Figure 3 It is a partial structural diagram of the positioning system of the present invention.

[0033] Figure 4 This is a schematic diagram of the exploded structure of part of the positioning system of the present invention.

[0034] Figure 5 This is a schematic diagram of the tibial top support rod and tibial fixation cable structure of the present invention.

[0035] Figure 6 This is a structural schematic diagram of the drilling guide arm of the present invention.

[0036] Figure 7 Schematic diagram of the flexible sensor layer structure of the present invention.

[0037] Figure 8 Schematic diagram of the flexible sensor of the present invention.

[0038] Figure 9 Schematic diagram of the signal processing and display unit of the present invention.

[0039] In the figure: 1. Positioning guide; 2. Guide support frame; 21. Support rod; 22. Support foot; 23. Connecting seat; 24. Sliding rod; 25. Buckle slot; 26. Top support rod connecting screw hole; 27. Limiting protrusion; 3. Drilling guide arm; 31. Sliding sleeve; 32. Buckle; 4. Tibial top support rod; 41. Cable connection hole; 42. Rotating handle; 5. Tibial fixation cable; 6. Signal processing and display unit; 7. Tibial bone tunnel drilling avoidance hole; 8. Tibial bone tunnel positioning hole; 11. Packaging layer; 12. Dielectric layer; 13. Electrode layer. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0041] like Figure 1 and Figure 2 As shown, a 3D printed guide positioning system for posterior cruciate ligament reconstruction includes: a positioning guide 1, a guide support frame 2, a drilling guide arm 3, a tibial top support rod 4, a tibial fixation cable 5 and a signal processing and display unit 6.

[0042] The positioning guide plate 1 is obtained by three-dimensional reconstruction of the tibia and manufactured by 3D printing technology. Specifically, the tibia is three-dimensionally reconstructed by preoperative MRI or CT imaging, and the position of the posterior cruciate ligament tibial stump is confirmed to obtain the tibial insertion positioning. The tibial tunnel is planned and determined by preoperative tibial anteromedial positioning (tibial tuberosity level, 2 cm lateral, 1.3 cm distal) to avoid the influence of "killer corner". Through the three-dimensional model of the tibia, the bone surface of the tibial insertion is extracted, and a precise surgical positioning guide plate model is established, which is manufactured by 3D printing technology.

[0043] The material of the positioning guide plate is composed of thermoplastic polyurethane (TPU) and polycaprolactone (PCL). TPU and PCL are dried in an oven at 80°C and 50°C respectively for 24 hours, and then the component ratio of 80% TPU and 20% PCL is manually configured. The temperature of the temperature control zone of the extruder cylinder is set to 180-190°C, and the screw rotation speed is 25 r / min. The extruded molten blend is cooled and formed in cooling water, and then granulated. The granules are dried in a vacuum oven at 50°C for 24 hours to remove moisture, and then injection molded using an injection molding machine. The raw material obtained by injection molding is sent to the discharge port of the 3D printer for 3D printing.

[0044] The positioning guide plate 1 is provided with a flexible sensor on the side that is attached to the bone surface. A tibial tunnel drilling avoidance hole 7 is provided in the middle of the positioning guide plate 1 and the flexible sensor to prevent the drilling of the tibial tunnel from affecting it.

[0045] As shown in Figure 7 The flexible sensor has a five-layer structure. The uppermost layer and the lowermost layer are PET film as encapsulation layer 11. The middle layer is a dielectric layer 12 composed of polystyrene microspheres, graphene and PDMS film. The dielectric layer is attached to the active carbon non-woven electrode layer 13 above and below, forming a capacitive pressure sensor.

[0046] The preparation process of the dielectric layer 12 includes: 1. Drop the photoresist evenly on the cleaned silicon wafer, and then spin coat it at a speed of 3000 r / min for 1 minute using an automatic photoresist coating machine to ensure that the photoresist is evenly and smoothly spread on the surface of the silicon wafer.

[0047] 2. Dry the silicon wafer on the drying table at 100°C for 2 minutes to obtain a smooth photoresist sacrificial layer.

[0048] 3. By drop casting method, slowly accumulate the mixed emulsion of graphene and polystyrene microspheres on the silicon wafer with the sacrificial layer, and let it stand until the solution volatilizes.

[0049] 4. Mix the PDMS prepolymer and the curing agent in a mass ratio of 10:1, stir for 10 minutes, and then let it stand for 30 minutes to remove the liquid surface bubbles.

[0050] 5. Pour the prepared PDMS mixture onto the substrate stacked with the graphene and polystyrene microsphere layers, spin-coat the PDMS mixture at a speed of 500 r / min for 1 minute using a spin coater, and then let it stand for 2 hours.

[0051] 6. Place the silicon wafer spin-coated with the PDMS mixture on a drying table at 75°C and heat for 2 hours to solidify into a film.

[0052] 7. Place the cured PDMS substrate in an acetone solution and completely peel the film from the silicon wafer. Then, rinse the solution attached to the film in deionized water to obtain the desired ultra-thin graphene, polystyrene microspheres, and PDMS composite dielectric layer film.

[0053] 8. Die-cut the dielectric film to form multiple small circular sensing elements and attach them to the electrode layer, such as Figure 8 shown.

[0054] The flexible sensor can detect the stress distribution between the positioning guide plate 1 and the tibia and obtain a stress cloud map, and the position of the positioning guide plate 1 can be adjusted through the cloud map.

[0055] like Figure 3 and Figure 4 As shown, the guide plate support frame 2 includes a support rod 21 and a support leg 22. The support rod 21 is fixed to the top of the support leg 22, and its first end is connected to the positioning guide plate 1. A connecting seat 23 is provided in the middle of the support rod 21, and a sliding rod 24 is formed from the connecting seat 23 to the second end of the support rod 21. The connecting seat 23 is provided with a snap groove 25.

[0056] Along its length, the support rod 21 comprises a first section connected to the positioning guide 1, a second section connected to the support foot 22, a connecting seat 23, and a sliding rod 24. The first section is used to extend into the patient's body to position the positioning guide 1 to its desired position. The connecting seat 23 is a circular ring structure that protrudes from the support rod 21 and is equipped with several locking grooves 25. The sliding rod 24 is a round rod with outwardly protruding stopper protrusions 27 on its circumference.

[0057] The top of the drilling guide arm 3 is provided with a sliding sleeve 31, and the bottom is provided with a tibial bone tunnel positioning hole 8. The sliding sleeve 31 is adapted to the slide bar 24 and can be slidably mounted on the slide bar 24. A positioning groove adapted to the limit protrusion 27 is opened in the sliding sleeve 31 to prevent the drilling guide arm 3 from rotating relative to the slide bar 24.

[0058] The sliding sleeve 31 is provided with a plurality of buckles 32 adapted to the buckle grooves 25 . The cooperation between the buckles 32 and the buckle grooves 25 can realize the fixed connection between the drilling guide arm 3 and the support rod 21 .

[0059] like Figure 3 、4 As shown in Figures 5 and 6, the main body of the drilling guide arm 3 is curved, bending from the connection base 23 toward the patient's tibia so that the tibial tunnel positioning hole 8 at its bottom abuts the tibial location to be drilled. During drilling, the tibial tunnel positioning hole 8 guides the drilling guide arm 3. The drilling guide arm 3 is made of stainless steel. Once the positioning guide plate 1 is properly positioned, the drilling guide arm 3 is fixedly connected to the support rod 21 to secure the position and facilitate the drilling operation.

[0060] The support leg 22 is preferably a U-shaped structure, with the top fixedly connected to the support rod 21, and a cross bar is provided on the two arms, and the cross bar is axially penetrated to open a top support rod connection screw hole 26. At the same time, a reinforcing beam is provided between the two arms of the support leg 22 to improve the structural strength.

[0061] like Figure 5 As shown, the outer surface of the tibial support rod 4 is provided with threads that threadably engage with the support rod connection screw hole 26 located in the middle of the support foot 22. The first end of the tibial support rod 4 is provided with a cable connection hole 41, and the second end is provided with a rotating handle 42. The tibial fixation cable 5 is connected to the cable connection hole 41 and is annularly sleeved on the patient's calf.

[0062] After the positioning guide 1 is positioned, the two tibial support rods 4 are screwed in and support the front end of the tibia to stabilize the entire device. The tibial fixation cable 5 is then passed through the cable connection hole 41 at the front end of the tibial support rods 4 to fix the patient's lower leg. Preferably, the tibial fixation cable 5 is made of multiple strands of silk and can be cylindrical or ribbon-shaped.

[0063] The signal processing and display unit 6 is used to process the stress signal detected by the flexible sensor and display the stress information and the information on the fit between the positioning guide and the bone surface.

[0064] like Figure 9 As shown, the signal processing and display unit 6 includes an AD conversion unit, an MCU processor, a battery, and a screen. The AD conversion unit is used to collect stress signals detected by the flexible sensor. The MCU processor is responsible for data sampling, raw digital signal filtering, stress information calculation, fit calculation, power management, and display processing. The battery provides power for the entire unit. The screen is used to display stress information and information about the fit between the positioning guide and the bone surface, and the screen is detachably fixed to the slide bar 24.

[0065] A 3D printed guide positioning method for posterior cruciate ligament reconstruction is based on the above-mentioned 3D printed guide positioning system for posterior cruciate ligament reconstruction, comprising the following steps:

[0066] S1, three-dimensional reconstruction of the tibia is performed through preoperative MRI or CT imaging, and the position of the posterior cruciate ligament tibial stump is confirmed to obtain the tibial insertion positioning, the tibial tunnel is determined through preoperative tibial anteromedial positioning point positioning planning, simulation is performed to avoid the influence of "killer corner";

[0067] S2, the bone surface of the tibial insertion is extracted through the three-dimensional model of the tibia to establish an accurate surgical positioning guide plate model, and the positioning guide plate is manufactured through 3D printing technology;

[0068] S3, the prepared positioning guide plate is fixedly connected with the supporting rod first end of the guide plate support frame, and a flexible sensor is attached to one side of the positioning guide plate;

[0069] S4, the guide plate support frame is moved to the patient's leg side, the positioning guide plate is placed near the tibial insertion position, the stress distribution between the positioning guide plate and the tibia is measured through the flexible sensor on the positioning guide plate, and the stress value distribution cloud map and the force value standard deviation are obtained through the signal processing unit. The display unit displays;

[0070] S5, adjust the position of the positioning guide plate through the cloud map displayed by the display unit, so that the force value standard deviation is below the set value, and determine that the positioning guide plate position is accurate at this time;

[0071] S6, move the drill guiding arm and fix it with the guide plate support frame 2 through the buckle, so that the tibial tunnel positioning hole at the bottom is fixed on one side of the tibia, and the drill positioning is realized.

[0072] The material of the positioning guide plate is composed of thermoplastic polyurethane TPU and polycaprolactone PCL; the manufacturing method comprises the following steps: drying TPU and PCL in 80℃ and 50℃ ovens for 24h respectively, then configuring the composition with component ratio of 80% TPU and 20% PCL; putting the composition into the extruder, at the same time setting the temperature of the temperature control zone of the extruder barrel to 180-190℃, the screw rotation speed to 25r / min, and melting extruding; cooling the extruded melt blend in cooling water to form, then granulating; drying the granules in a vacuum oven at 50℃ for 24h to remove moisture, then using an injection molding machine to perform injection molding, and sending the raw material obtained by injection molding to the discharge port of the 3D printer for 3D printing.

[0073] The flexible sensor adopts a five-layer structure, from top to bottom in turn: a PET film packaging layer, an activated carbon non-woven electrode layer, polystyrene microspheres, a graphene and PDMS film dielectric layer, an activated carbon non-woven electrode layer and a PET film packaging layer; the preparation process of the dielectric layer includes: 1, evenly drop the photoresist on the cleaned silicon wafer, and then use the automatic spin coater to spin at a speed of 3000r / min for 1 minute to ensure that the photoresist is evenly and smoothly spread on the surface of the silicon wafer; 2, place the silicon wafer on the baking table and dry at 100℃ for 2 minutes to obtain a smooth photoresist sacrificial layer; 3, slowly accumulate the mixed emulsion of graphene and polystyrene microspheres on the silicon wafer with the sacrificial layer by drop casting, and stand until the solution volatilizes; 4, mix the PDMS prepolymer and the curing agent according to the mass ratio of 10:1, stir for 10 min, and then stand for 30 min to remove the liquid surface bubbles; 5, pour the prepared PDMS mixed liquid on the substrate stacked with the graphene and polystyrene microsphere layer, and use the spin coater to spin the PDMS mixed liquid at a speed of 500r / min for 1 minute, and then stand for 2 hours; 6, place the silicon wafer with the PDMS mixed liquid on the baking table at a temperature of 75℃, and heat for 2 hours to solidify the film; 7, place the solidified PDMS substrate in the acetone solution, completely peel off the film from the silicon wafer, and then wash away the solution attached to the film in deionized water to obtain the required ultra-thin graphene, polystyrene microsphere and PDMS composite dielectric layer film; 8, cut the dielectric layer film to form multiple small circular sensing microelements, and attach them to the activated carbon non-woven electrode layer.

[0074] The above detailed the preferred embodiments of the present application. It should be understood that those skilled in the art can make many modifications and changes without creative labor based on the concept of the present application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment based on the prior art according to the concept of the present application shall be within the protection scope determined by the claims.

Claims

1. A 3D printed guide positioning system for posterior cruciate ligament reconstruction, characterized in that: include: A positioning guide plate (1), a guide plate support frame (2), a drilling guide arm (3), a tibial top support rod (4), a tibial fixation cable (5) and a signal processing and display unit (6); The positioning guide plate (1) is obtained by three-dimensional reconstruction of the tibia and is manufactured by 3D printing technology; a flexible sensor is provided on the side of the positioning guide plate (1) that is in contact with the bone surface; a tibial bone tunnel drilling avoidance hole (7) is provided through the middle of the positioning guide plate (1) and the flexible sensor; The guide plate support frame (2) includes a support rod (21) and a support foot (22); the support rod (21) is fixed to the top of the support foot (22), and its first end is connected to the positioning guide plate (1); a connecting seat (23) is provided in the middle of the support rod (21), and a sliding rod (24) is formed from the connecting seat (23) to the second end of the support rod (21); a buckle groove (25) is provided on the connecting seat (23); The top of the drilling guide arm (3) is provided with a sliding sleeve (31), and the bottom is provided with a tibial bone tunnel positioning hole (8); the sliding sleeve (31) is adapted to the sliding rod (24), and the sliding sleeve (31) is provided with a plurality of buckles (32) adapted to the buckle grooves (25); The outer peripheral surface of the tibial top support rod (4) is provided with a thread, which is threadedly matched with a top support rod connecting screw hole (26) provided in the middle of the supporting foot (22); the first end of the tibial top support rod (4) is provided with a cable connection hole (41), and the second end is provided with a rotating handle (42); The tibial fixation cable (5) is connected to the cable connection hole (41) and is annularly sleeved on the patient's calf; The signal processing and display unit (6) is used to process the stress signal detected by the flexible sensor and display stress information and information on the fitting condition between the positioning guide plate and the bone surface.

2. A 3D printed guide positioning system for posterior cruciate ligament reconstruction according to claim 1, characterized in that: The positioning guide plate (1) is made of thermoplastic polyurethane and polycaprolactone.

3. The 3D printing guide positioning system for posterior cruciate ligament reconstruction according to claim 1, characterized in that: The flexible sensor adopts a five-layer structure, wherein the top and bottom layers use PET films as encapsulation layers (11), the middle layer uses a dielectric layer (12) composed of polystyrene microspheres, graphene and PDMS film, and the dielectric layer is laminated with activated carbon non-woven fabric electrode layers (13) above and below, forming a capacitive pressure sensor.

4. The 3D printing guide positioning system for posterior cruciate ligament reconstruction according to claim 1, characterized in that: A limiting protrusion (27) is provided on the slide rod (24); and a positioning groove adapted to the limiting protrusion (27) is provided in the slide sleeve (31).

5. The 3D printing guide positioning system for posterior cruciate ligament reconstruction according to claim 1, characterized in that: The tibial fixation cable (5) is braided from multiple strands of silk and is a cylindrical or ribbon-shaped cable.

6. The 3D printing guide positioning system for posterior cruciate ligament reconstruction according to claim 1, characterized in that: The signal processing and display unit (6) includes an AD conversion unit, an MCU processor, a battery and a screen; the AD conversion unit is used to collect stress signals detected by the flexible sensor; the MCU processor is used for data sampling, original digital signal filtering, stress information calculation, fit calculation, power management and display processing; the battery supplies power to the entire unit; the screen is used to display stress information and information on the fit between the positioning guide plate and the bone surface, and the screen is detachably fixed to the slide bar (24).

7. The 3D printing guide positioning system for posterior cruciate ligament reconstruction according to claim 1, characterized in that: The positioning guide plate is made of thermoplastic polyurethane (TPU) and polycaprolactone (PCL); The manufacturing method includes the following steps: drying TPU and PCL in an oven at 80°C and 50°C for 24 hours, respectively, and then preparing a composition with a component ratio of 80% TPU and 20% PCL; placing the composition into an extruder, and at the same time setting the temperature of the temperature control zone of the extruder barrel to 180-190°C, the screw speed to 25r / min, and melt extrusion; cooling the extruded molten blend in cooling water to form it, and then granulating it; drying the granules in a vacuum oven at 50°C for 24 hours to remove moisture, and then using an injection molding machine for injection molding, and sending the raw materials obtained by injection molding to the discharge port of a 3D printer for 3D printing.

8. The 3D printing guide positioning system for posterior cruciate ligament reconstruction according to claim 1, characterized in that: The flexible sensor adopts a five-layer structure, which is from top to bottom: PET film encapsulation layer, activated carbon non-woven fabric electrode layer, polystyrene microspheres, graphene and PDMS film dielectric layer, activated carbon non-woven fabric electrode layer and PET film encapsulation layer; the preparation process of the dielectric layer includes:

1. Evenly drop the photoresist on the cleaned silicon wafer, and then use an automatic glue spreader to spin coat at a speed of 3000r / min for 1 minute to ensure that the photoresist is evenly and flatly covered on the surface of the silicon wafer; 2. Place the silicon wafer on a drying table and dry it at 100°C for 2 minutes to obtain a photoresist sacrificial layer with a smooth surface; 3. Slowly deposit the mixed emulsion of graphene and polystyrene microspheres on the silicon wafer with the sacrificial layer by the drip method, and let it stand until the solution evaporates; 4. Mix the PDMS prepolymer and the curing agent in a mass ratio of 10:1, stir for 10 minutes, and let it stand for 30 minutes. Remove bubbles from the liquid surface; 5. Pour the prepared PDMS mixture on the substrate stacked with graphene and polystyrene microsphere layers, use a glue roller to spin-coat the PDMS mixture at a speed of 500r / min for 1 minute, and then let it stand for 2 hours; 6. Place the silicon wafer spin-coated with the PDMS mixture on a drying table at a temperature of 75°C and heat for 2 hours to solidify into a film; 7. Place the cured PDMS substrate in an acetone solution, completely peel off the film from the silicon wafer, and then wash off the solution attached to the film in deionized water to obtain the required ultra-thin graphene, polystyrene microspheres and PDMS composite dielectric layer film; 8. Die-cut the dielectric layer film to form multiple small circular sensing micro-elements, and attach them to the activated carbon non-woven fabric electrode layer.

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