A custom calcaneal prosthesis for calcaneal replacement and manufacturing method thereof

Abstract

The present invention belongs to the field of orthopedic medical devices, and provides a customized calcaneal prosthesis for calcaneal replacement and a manufacturing method. The structural features of the calcaneal prosthesis are designed based on the bone morphology of the patient's foot, and include a calcaneal prosthesis main body. The calcaneal prosthesis main body is provided with a talocalcaneal joint surface, a calcaneocuboid joint surface, a calcaneal tendon hole, a locking screw hole, a heel support surface, a calcaneal tendon pull ring, a talus filling structure, and a trabecular porous structure. Since the calcaneal prosthesis adopts an integrated design with functional integration, the present invention uses a combination of 3D printing technology and conventional machining to reduce the processing difficulty, improve the processing efficiency, and achieve accurate position and direction of the locking screw inserted into the bone, as well as high-precision meshing of the thread between the locking screw and the locking screw hole, and firm locking.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and particularly to a customized calcaneal prosthesis for calcaneal replacement and a manufacturing method thereof. Background Art

[0002] The calcaneus is the largest load-bearing tarsal bone in the human body and is easily damaged. Calcaneal fractures are the most common among tarsal fractures. After the calcaneus is diseased, there are often symptoms such as heel pain, inability to stand or walk, local swelling, deformity, and pain on pressing. The anatomical environment around the calcaneus is complex, the fracture types and injury mechanisms are diverse, and there are often injuries and displacements of the subtalar joint and calcaneocuboid joint. Therefore, it is crucial to select a reasonable treatment plan and a highly matching prosthesis. Customized calcaneal prosthesis replacement has currently become an important method for calcaneal function reconstruction.

[0003] The patient has a defect in the talus and a simultaneous absence of the calcaneus. According to the treatment method of conventional implants, it is necessary to excise the defective talus and the collapsed calcaneus, and then perform double implantation of a talus prosthesis and a calcaneal prosthesis to complete the structural reconstruction of the talus and the calcaneus.

[0004] This solution has the following problems:

[0005] 1. A large amount of bone needs to be excised, the structure of the excision site is complex, the excision is difficult and time-consuming;

[0006] 2. To complete the structural reconstruction of the talus and the calcaneus, two types of implants, namely a talus prosthesis and a calcaneal prosthesis, need to be implanted. The number of implants is large and the weight is heavy;

[0007] 3. The cooperation between the two prostheses during the implantation process and the cooperation and positioning between the two prostheses and the human bone tissue are complex, and the surgical difficulty is high. Summary of the Invention

[0008] The object of the present invention is to provide a customized calcaneal prosthesis for calcaneal replacement and a manufacturing method thereof, which can solve the technical problems existing in the prior art. The customized calcaneal prosthesis is mainly used to restore the normal anatomical shape of the calcaneus and repair the defect of the subtalar joint, thereby reducing the functional disorders caused by calcaneal deformity, defect, etc.

[0009] The technical solution of the present invention is: a customized calcaneal prosthesis for calcaneal replacement. The structural features of the calcaneal prosthesis are designed based on the skeletal morphology of the patient's foot, including a calcaneal prosthesis main body. The calcaneal prosthesis main body is provided with a subtalar joint surface connected to the natural subtalar joint of the human body, a talus filling structure for repairing the defect of the talus on the subtalar joint surface, a calcaneocuboid joint surface connected to the natural cuboid bone of the human body, a calcaneal tendon hole and a calcaneal tendon pull ring for pulling and fixing the calcaneal tendon, locking screw holes for fixing the calcaneal prosthesis main body to the natural talus and cuboid bone of the human body, a heel support surface, and a trabecular porous structure.

[0010] Compared with current conventional standardized products, the customized calcaneal prosthesis is designed and manufactured according to the skeletal structure characteristics of the patient itself. The trabecular structure and talus filling structure make the performance in terms of matching degree, bonding property, etc. more excellent. The trabecular porous structure is a three-dimensional through porous structure, which is beneficial to bone ingrowth and at the same time plays a role in weight reduction.

[0011] According to the force analysis of the prosthesis and the force conduction characteristics, the main body of the calcaneal prosthesis includes a solid layer of the main body of the calcaneal prosthesis on the outside and a non-bearing layer of the main body of the calcaneal prosthesis. The solid layer of the main body of the calcaneal prosthesis is the main load-bearing structure and adopts a solid structure. The middle part of the main body of the calcaneal prosthesis is the non-main load-bearing layer part, which is light-weighted and is a hollow truss; the hollow truss is formed by the array arrangement and combination of hollow truss units. The shape of the hollow truss unit is selected according to mechanical properties and manufacturing requirements. The array arrangement angle of the hollow truss units is arranged according to the force conduction direction. The penetration direction of the beam of the hollow truss unit forms an angle of 30° - 60° with the gravity direction, providing support for the conduction of force in the hollow truss and realizing the light-weight design of the calcaneal prosthesis while ensuring mechanical properties.

[0012] A number of the locking screw holes are provided on the main body of the calcaneal prosthesis. The locking screw holes are matched with the locking screws. Through the locking screw holes, the main body of the calcaneal prosthesis can be fixed to the patient's talus and cuboid bone with the locking screws. The depth of the locking screw holes and the length of the locking screws used in cooperation are used to control the depth of the locking screws driven into the bone.

[0013] The locking screw includes a locking screw cap at the upper end and a locking screw body connected to the lower end of the locking screw cap. The locking screw cap is conical, and the outer surface of the cone is provided with tapered threads. When the locking screw is installed into the locking screw hole, there is a retaining ring between the meshing threads. Through the meshing of the threads between the locking screw and the locking screw hole, the retaining ring is squeezed into the thread gap, increasing the frictional force between the threads and playing a role in preventing the screw from withdrawing. The thread taper of the locking screw hole, the taper of the retaining ring, and the thread taper of the locking screw cap are the same.

[0014] The hollow truss penetrates the side surface of the main body of the calcaneal prosthesis and is used to remove the residual powder printed by 3D in the hollow structure. The retaining ring is provided with a deformation groove, making it easier for the retaining ring to generate deformation during the extrusion process.

[0015] The calcaneocuboid joint surface is arrayed with a trabecular porous structure.

[0016] The talocalcaneal joint surface is provided with a talus filling structure for repairing talus defects, and the surface is arrayed with a trabecular porous structure.

[0017] The trabecular structure is designed on the bone-bonding surface, which can increase the holding force between the calcaneal prosthesis and the bone contact surface, making the connection more firm. The pore diameter of the trabecular porous structure is 300-800 μm, the adjacent pores are interconnected, and the porosity is 50%-90%.

[0018] The Achilles tendon can be sutured around through the Achilles tendon hole, playing a role in traction and fixation. The heel support surface of the calcaneal prosthesis main body is an arc structure, which increases the contact area with the plantar soft tissue. When supporting the body weight, it can reduce the pressure on the plantar soft tissue.

[0019] A manufacturing method for manufacturing a customized calcaneal prosthesis for calcaneal replacement in the present application includes the following steps:

[0020] Step A00: Obtain the slice data of the foot bones through CT or MRT;

[0021] Step B00: Import the slice data of the foot bones into the software MIMICS and reconstruct the three-dimensional model of the foot bones;

[0022] Step C00: According to the reconstructed three-dimensional model of the foot bones, use CAD to design the structure of the customized calcaneal prosthesis.

[0023] Step D00: Conduct mechanical analysis on the customized calcaneal prosthesis, intercept the weight-reducing blocks at the non-main load-bearing positions of the prosthesis, and convert them into a hollow truss structure;

[0024] Step E00: At the positions where the customized calcaneal prosthesis contacts the talus and cuboid bones, the bone lap joint surface is designed as a trabecular porous structure;

[0025] Step F00: Import the designed customized calcaneal prosthesis model file into the rapid prototyping assistance software, first place it in space, add supports, then perform layer slicing processing, and import the layer data into the 3D printing device for printing;

[0026] Step G00: The manufacturing material is titanium alloy, cobalt-chromium alloy or ceramic powder material. After 3D printing is completed, perform heat treatment on the prosthesis to improve the physical and chemical properties of the material, remove internal stress, and process the locking screw holes by machining;

[0027] Step H00: After the prosthesis structure is processed, make the implant prosthesis through processes such as polishing, sandblasting, and cleaning.

[0028] The advantages and positive effects of the present invention are: By adopting the above technical solutions, the following beneficial effects are achieved:

[0029] 1. The calcaneus prosthesis has a talus filling structure for filling the missing talus and a main structure of the calcaneus prosthesis for reconstructing the calcaneus structure. The two structures are integrally designed, integrating the structures with two functions onto one prosthesis, which can reduce the number of implants, lower the degree of freedom of fit between the implant prosthesis and bone tissue, and reduce the surgical difficulty.

[0030] 2. For the problem of talus deficiency, the present invention adopts a method for filling the missing talus. According to the morphological pattern of the missing bone tissue of the talus, customized structural design is carried out, and filling is performed according to the missing contour pattern. While maximizing the retention of the original talus tissue, the reconstruction and supplementation of the missing tissue are realized, reducing the amount of bone resection, lowering the surgical difficulty, and reducing the surgical time.

[0031] 3. Since the calcaneus prosthesis adopts an integrated design with integrated functions, its structure is irregular and relatively complex, and the processing difficulty of conventional processing methods is large. The present invention adopts a method of combining 3D printing technology with conventional machining for processing and manufacturing: realizing the processing and manufacturing of the prosthesis contour features, hollow truss and trabecular porous structure through 3D printing technology, reducing the processing difficulty and improving the processing efficiency; since the processing accuracy of 3D printing technology cannot meet the design requirements of the locking screw holes, the locking screw holes are finely processed by conventional machining methods to ensure the high precision of the position, direction and thread structure of the locking screw holes. Thus, the accurate position and direction of the locking screw being driven into the bone are realized, and the high-precision meshing of the thread between the locking screw and the locking screw hole is achieved, ensuring firm locking. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic structural diagram of a specific embodiment of a customized calcaneus prosthesis for calcaneus replacement according to the present invention;

[0033] Figure 2 is a schematic diagram of the connection structure between the calcaneus prosthesis and the talus and cuboid bone and the force application direction of the calcaneus prosthesis shown in a specific embodiment of a customized calcaneus prosthesis for calcaneus replacement according to the present invention;

[0034] Figure 3 is a three-dimensional structural diagram of a stop ring in a specific embodiment of a customized calcaneus prosthesis for calcaneus replacement according to the present invention;

[0035] Figure 4 is a front view structural diagram of a stop ring in a specific embodiment of a customized calcaneus prosthesis for calcaneus replacement according to the present invention;

[0036] Figure 5 is a top view of a hollow truss unit in a specific embodiment of a customized calcaneus prosthesis for calcaneus replacement according to the present invention;

[0037] Figure 6 is a three-dimensional view of a hollow truss unit in a specific embodiment of a customized calcaneus prosthesis for calcaneus replacement according to the present invention;

[0038] Figure 7 It is a schematic diagram of the array arrangement structure of the hollow truss unit part in a specific embodiment of a customized calcaneal prosthesis for calcaneal replacement according to the present invention;

[0039] Figure 8 It is a schematic diagram of the locking screw structure in a specific embodiment of a customized calcaneal prosthesis for calcaneal replacement according to the present invention;

[0040] Figure 9 It is a schematic diagram of the structure in which the calcaneal prosthesis is connected to the talus through locking screws in a specific embodiment of a customized calcaneal prosthesis for calcaneal replacement according to the present invention.

[0041] In the figure:

[0042] 1. Calcaneal prosthesis main body; 2. Talocalcaneal joint surface; 3. Calcaneocuboid joint surface; 4. Achilles tendon hole; 5. Locking screw hole; 6. Heel support surface; 7. Hollow truss; 8. Achilles tendon pull ring; 9. Talus filling structure; 10. Trabecular porous structure; 11. Anti-back-off ring; 12. Talus; 13. Cuboid bone; 14. Deformation groove; 100. Locking screw head; 200. Locking screw body. Detailed implementation mode

[0043] Specific embodiment: As Figures 1-9 , a customized calcaneal prosthesis for calcaneal replacement according to the present invention, the structural characteristics of the calcaneal prosthesis are designed based on the bone morphology of the patient's foot. As shown in Figure 1 and Figure 2 , its structure includes: a calcaneal prosthesis main body 1, a talocalcaneal joint surface 2, a calcaneocuboid joint surface 3, a heel support surface 6, an Achilles tendon hole 4, and a locking screw hole 5; there is a cavity inside the calcaneal prosthesis main body 1, and the solid layer of the calcaneal prosthesis main body is the main load-bearing structure of the calcaneal prosthesis, which adopts a solid structure. The non-main load-bearing layer of the calcaneal prosthesis main body is a hollow truss 7 structure through finite element analysis. The non-main load-bearing layer of the calcaneal prosthesis main body is located in the cavity surrounded by the solid layer of the calcaneal prosthesis main body, and the cavity penetrates the calcaneal prosthesis.

[0044] The customized calcaneal prosthesis is 3D printed to produce a hollow truss 7 structure with a weight reduction function. As shown in Figure 2 , after analyzing the pressure direction received by the human calcaneus, according to the main pressure conduction direction, the solid layer of the calcaneal prosthesis main body designed is a solid structure, which is the main load-bearing position of the calcaneal prosthesis, and the non-main load-bearing layer of the calcaneal prosthesis main body is a hollow truss 7 structure, which is the non-main load-bearing position of the calcaneal prosthesis.

[0045] The non-main load-bearing layer of the calcaneal prosthesis main body in the middle of the calcaneal prosthesis main body is arrayed with a hollow truss 7 structure for prosthesis lightweighting; the hollow truss 7 structure penetrates the calcaneal prosthesis main body 1. For the convenience of description, it is defined that the direction from the calcaneocuboid joint surface 3 to the heel support surface 6 is the front-back direction. AsFigure 1 and Figure 2 As shown in Figure 2 , select the penetration direction according to the actual situation of the calcaneal prosthesis. The function of penetration is to remove the residual powder printed by 3D in the structure of the hollow truss 7 (the penetration direction is except along the up and down direction of the calcaneal prosthesis). In this embodiment, the hollow truss 7 penetrates the main body 1 of the calcaneal prosthesis from the left and right directions to remove the residual powder printed by 3D in the structure of the hollow truss 7. The structure of the hollow truss 7 of the customized calcaneal prosthesis is formed by arranging and combining hollow truss units. The diameter of the beam of the hollow truss is greater than 800μm, and the hollow aperture is greater than 1000μm. The hollow aperture refers to the aperture of the hole formed by two adjacent hollow truss units in the same horizontal plane in the hollow truss 7. The term "beam" refers to the part connecting two cross-linking points in the three-dimensional network structure formed by the hollow truss. The diameter of the "beam" refers to the diameter of the connecting part between two cross-linking points in the three-dimensional network structure formed by the hollow truss.

[0046] The structural form of each hollow truss unit includes but is not limited to hexahedron, octahedron, dodecahedron, which can be selected according to mechanical properties and manufacturing requirements, and then the arrangement unit can be changed according to actual applications. As Figure 2 shown in Figure 2 , F represents the force conduction direction. In this specific embodiment, the hollow truss unit selects a regular octahedron unit as Figure 5 and Figure 6 shown in Figure 6 , and the array arrangement is as Figure 7 shown in Figure 7 , so that the force can be evenly distributed under force; the array arrangement angle of the regular octahedron unit is arranged according to the force conduction direction, and the penetration direction of the beam of the regular octahedron unit forms an angle of 30°-60° with the gravity direction, providing support for the conduction of force in the structure of the hollow truss 7, improving the fatigue resistance of the prosthesis, and thus realizing the lightweight design of the prosthesis while ensuring mechanical properties.

[0047] The calcaneocuboid joint surface 3 is connected to the natural cuboid bone of the human body. The surface of the calcaneocuboid joint surface 3 is arrayed with a trabecular porous structure 10. The trabecular porous structure is an irregular three-dimensional network, specifically like loofah sponge or sponge-like. Constructing a trabecular porous structure on the titanium alloy surface is more conducive to the growth of bone tissue, and can make the bone tissue and the matrix have better mechanical and chemical locking, preventing loosening.

[0048] The talocalcaneal joint surface 2 is connected to the natural talocalcaneal joint of the human body. A talus filling structure 9 for repairing talus defects is provided on the talocalcaneal joint surface 2, and the surface is arrayed with a trabecular porous structure 10.

[0049] Compared with the healthy talus, there is a defect in the patient's talus. The customized calcaneal prosthesis is designed with a talus filling structure 9 for filling the missing part of the talus. For the problem of talus deficiency, the present invention adopts a method for filling the missing talus. According to the morphological pattern of the missing bone tissue of the talus, a customized structure design is carried out, and filling is performed according to the missing contour pattern. While maximizing the retention of the original talus tissue, the reconstruction and supplementation of the missing tissue are achieved, reducing the amount of bone resection, lowering the surgical difficulty, and shortening the operation time.

[0050] The calcaneal prosthesis has a talus filling structure 9 for filling the missing talus and a calcaneal prosthesis main body 1 structure for calcaneal structure reconstruction. And the two structures are integrally designed, integrating the structures with two functions onto one prosthesis, which can reduce the number of implants, lower the degree of freedom of cooperation between the implant prosthesis and bone tissue, and reduce the surgical difficulty.

[0051] The trabecular porous structure 10 is designed on the bone-bonding surface, which can increase the holding force between the part involved in the calcaneal prosthesis and the bone contact surface, making the connection more firm. The pore diameter of the trabecular porous structure is 300 - 800 μm, the adjacent pores are interconnected, and the porosity is 50% - 90%.

[0052] The heel support surface 6 is located at the posterior lower heel position of the calcaneal prosthesis main body. The heel support surface 6 of the customized calcaneal prosthesis is an arc structure, that is, a heel arc surface, which increases the contact area with the plantar soft tissue. Under the condition of supporting the body weight, it can reduce the pressure on the plantar soft tissue.

[0053] The natural heel support surface 6 of the human calcaneus is not a smooth arc shape, but a structure with a concave middle and convex sides, similar to a ridge. However, if the heel support surface 6 of the calcaneal prosthesis is made into a shape similar to the natural heel support surface, because the prosthesis is made of metal material, affected by materials and other factors, the pressure on the plantar soft tissue at the convex parts on both sides increases. In the long term, the convex parts on both sides of the heel support surface 6 of the calcaneal prosthesis will continue to pierce downward into the plantar soft tissue, which may cause soft tissue injury, and in severe cases, it may cause penetration. After improvement in this application, the heel support surface 6 is designed as a smooth arc shape to improve the above problems.

[0054] A number of locking screw holes 5 are provided on the calcaneal prosthesis main body 1. Through the locking screw holes 5, the calcaneal prosthesis main body 1 can be fixed to the patient's talus and cuboid bone with locking screws.

[0055] Through the calcaneal prosthesis body, the locking screws are fixed to the talus and cuboid bone through the locking screw holes. Two or more locking screws are required, and the locking screws are not parallel to each other. They are driven into the bone tissue at a cross angle, resulting in a more stable combination. By controlling the depth of the locking screw holes 5 and the length of the locking screws used in combination, the depth of the locking screws driven into the bone is controlled to ensure that the locking screws driven into the bone do not penetrate the bone and do not damage the outer surface of the bone, avoiding scratching the articular surface and soft tissues. At the same time, the length of the locking screws driven into the bone is as long as possible to increase the holding force. As Figure 9 shown, it is a schematic structural diagram of the calcaneal prosthesis connected to the talus through the locking screws.

[0056] The locking screw holes penetrate through the calcaneal prosthesis body where the calcaneocuboid joint surface 3 is located and continue to extend into the cuboid bone (without penetrating the cuboid bone), and the calcaneal prosthesis body where the talocalcaneal joint surface 2 is located and extend into the talus (without penetrating the talus). The locking screws cooperate with the locking screw holes to act on the calcaneocuboid joint surface 3 of the calcaneal prosthesis body 1 and are connected to the cuboid bone screws, and act on the talocalcaneal joint surface 2 of the calcaneal prosthesis body 1 and are connected to the talus screws, increasing the stability of the implanted calcaneal prosthesis.

[0057] When using the locking screws to install them into the locking screw holes, there is an anti-backlash ring 11 made of ultra-high molecular weight polyethylene material between the meshing threads. Through the meshing of the threads between the locking screws and the locking screw holes 5, the anti-backlash ring 11 is squeezed into the thread gap, increasing the frictional force between the threads and playing a role in preventing the locking screws from backing out.

[0058] Ultra-high molecular weight polyethylene (UHMW-PE) is polyethylene with a molecular weight of more than 1 million. Ultra-high molecular weight polyethylene is a high molecular compound with excellent wear resistance, self-lubrication, relatively high strength, stable chemical properties, and strong anti-aging performance.

[0059] The anti-backlash ring 11 includes an anti-backlash ring body and a deformation groove located on the anti-backlash ring body, making it easier for the anti-backlash ring 11 to deform during the extrusion process. The wall thickness of the anti-backlash ring 11 is 0.1 - 0.3 mm. According to the specifications of the locking screws used, the height h of the anti-backlash ring (here the height h of the anti-backlash ring refers to the height of the anti-backlash ring 11) is designed to be 1.5 times the pitch of the locking screw threads, and the taper α of the anti-backlash ring is 15° - 30°, as Figure 5 shown.

[0060] As Figure 8 shown, the locking screw includes a locking screw head 100 at the upper end and a locking screw body 200 connected to the lower end of the locking screw head 100. The locking screw head 100 is conical, and the outer surface of the cone is provided with tapered threads. The taper of the locking screw head threads is β.

[0061] The locking screw hole 5, anti-backout ring 11, and locking screw of the calcaneal prosthesis need to be used in combination. When in use, the locking screw extends from one side of the calcaneal prosthesis to the natural bone for threaded connection. The threaded hole at the entrance of the locking screw hole on the calcaneal prosthesis is a tapered screw hole for mating with the locking screw head 100. The thread taper of the locking screw hole 5, the taper α of the anti-backout ring 11, and the thread taper β of the locking screw head are the same. When in use, the anti-backout ring 11 is sleeved onto the tapered thread position of the locking screw head 100 and then together inserted into the locking screw hole 5 on the calcaneal prosthesis, and then screwed in and tightened. The tapered screw hole of the locking screw enters the tapered screw hole of the locking screw hole 5. Through the meshing of the threads between the tapered thread of the locking screw head 100 and the tapered screw hole of the locking screw hole 5, the anti-backout ring 11 is extruded into the thread gap, increasing the frictional force between the threads, playing a role in preventing the screw from backing out, and the depth of the locking screw driven into the bone can be controlled through the length of the locking screw used in conjunction with the tapered thread structure of the locking screw head 100 to achieve positioning, without the need to separately set a stepped hole for limiting.

[0062] The height h and taper α of the anti-backout ring 11 are the key to achieving this function. The taper α in conjunction with the height h determines the final position of the anti-backout ring 11 on the locking screw head 100.

[0063] The Achilles tendon can be loop-sutured through the Achilles tendon hole 4 to play a role in traction and fixation. Due to the absence of the calcaneus in the patient, the Achilles tendon has atrophied and cannot be stretched to the normal length. Therefore, when designing the Achilles tendon hole 4, there are the following two characteristics: In the sagittal plane direction, the position of the Achilles tendon hole 4 is set above the attachment point of the Achilles tendon on the calcaneus, reducing the stretching length of the atrophied Achilles tendon and facilitating intraoperative suture. In the horizontal plane direction, the position of the Achilles tendon hole 4 is behind the talus. After the Achilles tendon is sutured, a traction force arm can be formed, enabling the calcaneal prosthesis and the Achilles tendon to restore the normal physiological mechanical form.

[0064] The diameter of the Achilles tendon is relatively thick. In order to smoothly pass through the Achilles tendon hole 4 for loop-suturing, the aperture range of the Achilles tendon hole 4 is: 8 mm - 20 mm. The structure of the Achilles tendon hole 4 is composed of a smooth curved surface, without structures such as sharp corners and sharp edges that may cause abrasion of the Achilles tendon. The Achilles tendon hole 4 is recessed into the interior of the calcaneal prosthesis. An Achilles tendon pull ring 8 is provided on the Achilles tendon hole 4. The Achilles tendon is passed through the Achilles tendon hole 4 and wound around the position of the Achilles tendon pull ring 8, and then sutured, which can reduce the protruding length of the Achilles tendon pull ring 8, ensuring that the protruding length of the Achilles tendon pull ring 8 does not exceed the tail of the calcaneal prosthesis, preventing the heel skin from protruding due to the protrusion of the Achilles tendon pull ring 8.

[0065] Surgical steps:

[0066] Step 100: Remove the residual diseased calcaneus and talus, and implant the calcaneal prosthesis.

[0067] Step 200: Adjust the position of the calcaneal prosthesis so that it fits with the talus and cuboid bone and restores to the normal physiological form.

[0068] Step 300: Fit the anti-backlash ring 11 onto the tapered thread position of the locking screw cap 100, insert it into the locking screw hole 5 of the calcaneal prosthesis, and screw the locking screw into the bone along the direction of the locking screw hole 5 for locking and fixing.

[0069] Step 400: Traction the patient's Achilles tendon through the Achilles tendon hole 4, wind it around the Achilles tendon pull ring 8 outside the Achilles tendon hole 4 and suture it for fixation.

[0070] Step 500: Suture the wound.

[0071] A customized calcaneus manufacturing method for calcaneal replacement, characterized by including the following steps:

[0072] Step A00: Obtain the slice data of the foot bone through CT or MRT;

[0073] Step B00: Import the slice data of the foot bone into the software MIMICS and reconstruct the three-dimensional model of the foot bone;

[0074] Step C00: According to the reconstructed three-dimensional model of the foot bone, use CAD to design the structure of the customized calcaneal prosthesis.

[0075] Step D00: Conduct a mechanical analysis on the customized calcaneal prosthesis, intercept the weight reduction block at the non-main load-bearing position of the calcaneal prosthesis, and convert it into a hollow truss structure.

[0076] Step E00: For the position where the customized calcaneal prosthesis contacts the talus and cuboid bone, the bone lap joint surface is designed as a trabecular porous structure.

[0077] Step F00: Import the designed customized calcaneal prosthesis model file into the rapid prototyping auxiliary software, first place it in the spatial position, add supports, then conduct layer slicing processing, and import the layer data into the 3D printing device for printing.

[0078] Step G00: The manufacturing material is titanium alloy, cobalt-chromium alloy or ceramic powder material. After 3D printing is completed, conduct heat treatment on the prosthesis to improve the physical and chemical properties of the material, remove internal stress, and machine the locking screw hole.

[0079] Step H00: After the prosthesis structure processing is completed, make the implant prosthesis through processes such as polishing, sandblasting, and cleaning.

[0080] Considering that there is an inflammatory risk if the particles fall off in the human body environment, it is necessary to conduct surface treatment on them. The commonly used treatment method is sandblasting, which can remove the residual semi-molten particles while forming a rough surface micron structure.

[0081] In the above step D00, a parametric programming technique is used to establish a library of hollow truss units. A hollow truss unit suitable for the implantation site is selected from the library of hollow truss units, and the arrangement units are changed according to the actual application to fill the calcaneal prosthesis.

[0082] Since the calcaneal prosthesis adopts an integrated design with functional integration, its structure is irregular and relatively complex, and it is difficult to process by conventional processing methods. The present invention adopts a method combining 3D printing technology and conventional machining for processing and manufacturing: the processing and manufacturing of the prosthesis contour features, hollow trusses and trabecular porous structures are realized through 3D printing technology, reducing the processing difficulty and improving the processing efficiency; since the processing accuracy of 3D printing technology cannot meet the design requirements of the locking screw holes 5, the locking screw holes 5 are finely processed by conventional machining to ensure the high precision of the position, direction and thread structure of the locking screw holes 5. Thus, the accurate position and direction of the locking screw inserted into the bone are realized, and the high-precision meshing of the threads between the locking screw and the locking screw holes 5 is achieved, ensuring firm locking.

[0083] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0084] The above has described an embodiment of the present invention in detail, but the content described is only the preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the present invention application should still fall within the scope covered by the patent of the present invention.

Claims

1. A customized calcaneal prosthesis for calcaneal replacement, characterized in that: The structural features of the calcaneal prosthesis are designed based on the skeletal morphology of the patient's foot, including the main body of the calcaneal prosthesis. The main body of the calcaneal prosthesis is provided with a talocalcaneal joint surface that connects to the natural human talus. The talocalcaneal joint surface is provided with a talus filling structure for repairing talus defects. The talus filling structure fills according to the morphological pattern of the missing bone tissue of the talus, in accordance with the missing contour. There is a calcaneocuboid joint surface that connects to the natural human cuboid bone. A calcaneal tendon pull ring is provided on the calcaneal tendon hole. The calcaneal tendon is passed through the calcaneal tendon hole and wound around the position of the calcaneal tendon pull ring, and then sutured. There are locking screw holes for fixing the main body of the calcaneal prosthesis to the natural human talus and cuboid bone. There is a heel support surface and a trabecular porous structure.

2. The customized calcaneal prosthesis for calcaneal replacement according to claim 1, characterized in that: According to the force analysis and force conduction characteristics of the prosthesis, the main body of the calcaneal prosthesis includes a solid layer of the main body of the calcaneal prosthesis on the outside and a non-load-bearing layer of the main body of the calcaneal prosthesis. The solid layer of the main body of the calcaneal prosthesis is the main load-bearing structure and adopts a solid structure. The non-main load-bearing layer of the main body of the calcaneal prosthesis has been lightened and is a hollow truss. The hollow truss is formed by the array arrangement and combination of hollow truss units. The shape of the hollow truss unit is selected according to mechanical properties and manufacturing requirements. The array arrangement angle of the hollow truss units is arranged according to the direction of force conduction. The penetration direction of the beam of the hollow truss unit forms an angle of 30°-60° with the direction of gravity, providing support for the conduction of force in the hollow truss and realizing the lightweight design of the calcaneal prosthesis while ensuring mechanical properties.

3. The customized calcaneal prosthesis for calcaneal replacement according to claim 2, characterized in that: A number of the locking screw holes are provided on the main body of the calcaneal prosthesis. The locking screw holes match the locking screws. Through the locking screw holes, the main body of the calcaneal prosthesis can be fixed to the patient's talus and cuboid bone with the locking screws. The depth of the locking screw holes and the length of the locking screws used in combination are used to control the depth of the locking screws driven into the bone.

4. The customized calcaneal prosthesis for calcaneal replacement according to claim 3, characterized in that: The locking screw includes a locking screw cap at the upper end and a locking screw body connected to the lower end of the locking screw cap. The locking screw cap is conical, and the outer surface of the cone is provided with tapered threads. When the locking screw is used to install into the locking screw hole, there is a retaining ring between the meshing threads. Through the meshing of the threads between the locking screw and the locking screw hole, the retaining ring is squeezed into the thread gap, increasing the friction between the threads and playing a role in preventing the screw from withdrawing. The thread taper of the locking screw hole, the taper of the retaining ring, and the thread taper of the locking screw cap are the same.

5. The customized calcaneal prosthesis for calcaneal replacement according to claim 4, characterized in that: The hollow truss penetrates the side surface of the main body of the calcaneal prosthesis for removing the residual powder printed by 3D in the hollow structure. The retaining ring is provided with a deformation groove, making it easier for the retaining ring to deform during the extrusion process.

6. The customized calcaneal prosthesis for calcaneal replacement according to claim 5, wherein: The calcaneocuboid joint surface is arrayed and distributed with the trabecular porous structure.

7. The customized calcaneal prosthesis for calcaneal replacement according to claim 6, characterized in that: The talocalcaneal joint surface is provided with the talus filling structure for repairing talus defects, and the surface is arrayed and distributed with the trabecular porous structure.

8. The customized calcaneal prosthesis for calcaneal replacement according to claim 7, characterized in that: The trabecular structure is designed on the bone-bonding surface, which can increase the holding force between the calcaneal prosthesis and the bone contact surface and make the connection more firm. The pore diameter of the trabecular porous structure is 300-800 μm, and the adjacent pores are interconnected with each other, and the porosity is 50%-90%.

9. The customized calcaneal prosthesis for calcaneal replacement according to claim 8, characterized in that: The Achilles tendon can be sutured around through the Achilles tendon hole to play a role in traction and fixation. The heel support surface of the calcaneal prosthesis main body is an arc structure, which increases the contact area with the plantar soft tissue. When supporting the body weight, it can reduce the pressure on the plantar soft tissue.

10. A manufacturing method for a customized calcaneal prosthesis for calcaneal replacement according to any one of claims 2-9, characterized in that: It includes the following steps: Step A00: Obtain the slice data of the foot bones through CT or MRT; Step B00: Import the slice data of the foot bones into the software MIMICS and reconstruct the three-dimensional model of the foot bones; Step C00: According to the reconstructed three-dimensional model of the foot bones, use CAD to customize the structural design of the calcaneal prosthesis; Step D00: Conduct a mechanical analysis on the customized calcaneal prosthesis, intercept a weight-reducing block at the non-main load-bearing position of the prosthesis, and convert it into a hollow truss structure; Step E00: At the position where the customized calcaneal prosthesis contacts the talus and cuboid bone, the bone overlapping surface is designed as a trabecular porous structure; Step F00: Import the designed customized calcaneal prosthesis model file into the rapid prototyping auxiliary software, first place the spatial position, add supports, then perform layer slicing processing, and import the layer data into the 3D printing device for printing; Step G00: The manufacturing material is titanium alloy, cobalt-chromium alloy or ceramic powder material. After 3D printing, perform heat treatment on the prosthesis to improve the physical and chemical properties of the material, remove internal stress, and machine the locking screw holes; Step H00: After the prosthesis structure is processed, make the implant prosthesis through polishing, sandblasting and cleaning processes.

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