Positionable 3D printed elbow joint prosthesis structure

Abstract

The invention relates to the technical field of medical instruments, in particular to a positionable 3D printed elbow joint prosthesis structure which comprises an upper prosthesis and a lower prosthesis, and a connecting assembly used for connecting the upper prosthesis and the lower prosthesis is arranged between the upper prosthesis and the lower prosthesis; the connecting assembly comprises a connecting piece arranged at one end of the lower prosthesis, a fixing shaft is fixedly connected to the connecting piece, one end of the upper prosthesis is hinged to the fixing shaft, and the lower prosthesis swings on the fixing shaft; the connecting piece is provided with an adjustable positioning assembly used for limiting the swing angle of the lower prosthesis. In an artificial elbow joint replacement operation, the 3D printing technology is used for achieving adaptation of the prosthesis to the distal humerus and the proximal ulna of the patient, and meanwhile the limiting angle can be customized according to the elbow joint movement range of each patient.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to a positionable 3D-printed elbow joint prosthesis structure. Background Technology

[0002] When the elbow joint is damaged due to rheumatism, osteoarthritis, or trauma, it loses its function and causes severe pain. In such cases, elbow replacement surgery is necessary to restore elbow joint function. With the promotion of 3D printing technology in the field of medical devices, positionable 3D-printed elbow joint prostheses are gradually becoming an important option for elbow replacement surgery because they can be customized to individual needs.

[0003] In existing technologies, for example, the Coonrad-Morrey elbow prosthesis, a widely used semi-restricted elbow prosthesis in clinical practice, although not entirely formed by 3D printing, incorporates 3D printing customization technology into some components—such as the personalized base of the humeral side prosthesis—allowing the prosthesis shape to be adjusted according to the patient's distal humeral anatomy.

[0004] However, in actual use of this type of elbow prosthesis, its limiting structure is a fixed design, making it difficult to customize the limiting angle according to each patient's elbow joint range of motion. Some patients are prone to prosthesis loosening or damage due to excessive activity after surgery. Therefore, it is necessary to propose a positionable 3D-printed elbow prosthesis structure to solve the problem that the existing elbow prosthesis's limiting structure is a fixed design, making it difficult to customize the limiting angle according to each patient's elbow joint range of motion, and that some patients are prone to prosthesis loosening or damage due to excessive activity after surgery. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a positionable 3D-printed elbow joint prosthesis structure for use in artificial elbow joint replacement surgery. 3D printing technology is employed to adapt the prosthesis to the distal humerus and proximal ulna of the patient, while allowing for customized positioning angles based on each patient's elbow joint range of motion.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: a positionable 3D-printed elbow joint prosthesis structure, comprising an upper prosthesis and a lower prosthesis, wherein a connecting assembly for connecting the upper and lower prostheses is provided between the upper and lower prostheses; the connecting assembly includes a connector disposed at one end of the lower prosthesis, a fixed shaft fixedly connected to the connector, a connecting rod hinged to the fixed shaft, the end of the connecting rod away from the fixed shaft being fixedly connected to one end of the lower prosthesis, and the lower prosthesis swinging on the fixed shaft; the connector is provided with an adjustable positioning assembly for limiting the swing angle of the lower prosthesis.

[0007] The technical principles of the above solution are as follows:

[0008] Preoperatively, the shapes of the lower and upper prostheses were designed based on the anatomical structure of the distal humerus, and the range of motion of the elbow joint was determined using preoperative imaging data. The lower and upper prostheses were then printed using SLM 3D printing technology. During surgery, the diseased tissue in the elbow was first cleared to expose the normal bone surfaces of the distal humerus and proximal ulna. The upper prosthesis was then installed at the osteotomy site of the distal humerus using a bio-fixation method, and the lower prosthesis was installed at the corresponding osteotomy site of the proximal ulna. After initial fixation of the lower and upper prostheses, the end of the connecting rod furthest from the fixation axis was connected and fixed to one end of the upper prosthesis. At this point, the upper prosthesis could swing around the fixation axis. Simultaneously, the adjustable positioning components were adjusted based on the elbow joint range of motion data to limit the swing range of the upper prosthesis, preventing it from exceeding the preoperatively adapted range of motion and avoiding postoperative overuse that could lead to prosthesis loosening or damage. Ultimately, this achieved artificial elbow joint replacement and personalized functional recovery.

[0009] The above approach has the following beneficial effects:

[0010] 1. This invention uses SLM 3D printing technology combined with the patient's preoperative imaging data to design the prosthesis shape, which can achieve a high fit between the lower and upper prostheses and the distal humerus and proximal ulna of the patient, respectively. Compared with some existing custom prostheses, the fit accuracy is higher, which can reduce the gap between the prosthesis and bone tissue, reduce the risk of micromovement of the prosthesis after surgery, and lay the foundation for long-term stable use.

[0011] 2. The adjustable positioning component of this invention can flexibly adjust the limiting angle according to the patient's individual elbow joint range of motion data, breaking the limitations of the existing prosthesis fixation and limiting structure. It can match the postoperative activity needs of different patients, effectively avoid prosthesis loosening or damage caused by excessive activity, and improve postoperative safety and patient fit.

[0012] 3. This invention uses a biological fixation method to install the prosthesis. Combined with the structural advantages of 3D printed prostheses, it can promote osseointegration between the prosthesis and autologous bone. Compared with traditional bone cement fixation, it reduces problems such as bone cement aging and loosening, and extends the service life of the prosthesis. Each part of the structure is detachable, which reduces the difficulty for doctors to install the prosthesis. At the same time, it is also convenient to adjust the position of the prosthesis or perform maintenance after surgery.

[0013] Furthermore, the connector includes symmetrically detachably connected brackets to one end of the upper prosthesis, a fixing shaft passing through one of the brackets and slidingly engaging with the bracket, and the other bracket being fixedly connected to one end of the fixing shaft.

[0014] Beneficial effects: The symmetrically arranged brackets can provide stable support for the fixed axis from both sides, improving the overall structural strength of the connecting components; at the same time, the detachable design also makes it convenient to replace or repair the connecting parts individually after surgery, reducing maintenance costs.

[0015] Furthermore, the adjustable positioning component includes symmetrically rotatably fitted collars on a fixed shaft. One collar has several protruding teeth circumferentially fixedly connected to one side wall, and one bracket has several toothed grooves circumferentially opened on one side wall, with the protruding teeth meshing with their adjacent toothed grooves. A limit rod is fixedly connected between adjacent collars, and the limit rod is used to limit the rotation angle of the connecting rod. A U-shaped block is provided on one end of the fixed shaft, and eccentric wheels are fixedly connected to both ends of the U-shaped block. The eccentric wheels are eccentrically hinged to the side walls of their adjacent fixed shafts.

[0016] Beneficial effects: By rotating the collar, the limiting rod is rotated to the appropriate position. At this time, the U-shaped block is turned, which in turn drives the convex teeth on the adjacent collar and the tooth groove on the bracket to mesh, thereby locking the rotation of the collar. At this time, the limiting rod can directly prevent the upper prosthesis from swinging excessively, realizing physical limitation, and thus realizing the adjustment of the swing angle range of the upper prosthesis.

[0017] Furthermore, one of the support brackets has several scale lines circumferentially opened on its side wall.

[0018] Beneficial effects: The scale lines provide doctors with an intuitive reference for adjusting the limiting angle of the adjustable positioning component, enabling doctors to adjust the limiting angle to the target value based on the range of motion data determined by the patient's preoperative imaging examination. At the same time, the scale lines also facilitate the observation of whether the limiting angle has changed during postoperative follow-up examinations, providing a basis for assessing the prosthesis's usage status.

[0019] Furthermore, both the upper and lower prostheses are provided with positioning auxiliary components to assist in the installation of the upper and lower prostheses; the positioning auxiliary components include sleeves, which are fitted onto the upper and lower prostheses, and each sleeve is provided with a locking element for locking the upper and lower prostheses.

[0020] Beneficial effects: The cannula can be pre-assembled with the prosthesis before surgery. During the operation, the cannula can be matched with the osteotomy surface of the patient's bone to quickly determine the installation position of the prosthesis, reduce the doctor's reliance on the judgment of the anatomical structure, and reduce the difficulty of the operation.

[0021] Furthermore, several through holes are opened on the side wall of the casing.

[0022] Beneficial effects: When the prosthesis is installed using a biological fixation method, the through-hole allows bone growth factors or bone cells to come into contact with the prosthesis surface, promoting osseointegration between the prosthesis and autologous bone.

[0023] Furthermore, the lower prosthesis is made of titanium alloy matrix material and is coated with hydroxyapatite coating.

[0024] Beneficial effects: The titanium alloy matrix has excellent mechanical strength and biocompatibility, and can withstand the impact of external forces during elbow joint movement, avoiding prosthesis deformation or breakage; the chemical composition of the hydroxyapatite coating is similar to the inorganic components of human bone tissue, which can guide bone cells to adhere, proliferate and differentiate on the coating surface, promote the osseointegration of the lower prosthesis with the distal humerus, shorten the bone healing time, and at the same time reduce the rejection reaction between the prosthesis and bone tissue, thereby improving the biocompatibility and long-term fixation effect of the prosthesis.

[0025] Furthermore, the upper prosthesis is made of porous titanium alloy core material with a porosity of 60%-70% and a pore size of 300-500μm.

[0026] Beneficial effects: The porous structure with this porosity and pore size range can provide sufficient growth space for bone cells, facilitating bone cells to grow deep into the pores, forming an integrated fusion and improving the bone integration effect.

[0027] Furthermore, a buffer assembly is provided at the connection between the connecting rod and the upper prosthesis; the buffer assembly includes a buffer sleeve fixedly connected to one end of the upper prosthesis, a buffer spring is provided inside the buffer sleeve, one end of the buffer spring is fixedly connected to the upper prosthesis, and the other end of the buffer spring is fixedly connected to the connecting rod.

[0028] Beneficial effects: The cushioning spring can absorb some of the impact force when the elbow joint moves. If the patient exerts force accidentally or the range of motion suddenly increases, the elastic deformation of the spring can buffer the force at the connection between the connecting rod and the upper prosthesis, avoiding local stress concentration that could lead to damage to the prosthesis or bone.

[0029] Furthermore, the porous titanium alloy core of the upper prosthesis is also composited with bioactive ceramic particles, wherein the bioactive ceramic particles are β-tricalcium phosphate material with a particle size of 50-100μm and a volume fraction of 8%-12% in the porous titanium alloy core.

[0030] Beneficial effects: β-tricalcium phosphate has good biodegradability and bone-guiding properties. It can slowly degrade in vivo and be replaced by new bone tissue, avoiding foreign body reactions that may be caused by long-term retention of the prosthesis in the body. The calcium and phosphorus ions released during its degradation process can provide nutrients for osteoblast growth and guide osteoblasts to grow into the porous core, accelerating the osseointegration process. The particle size and volume fraction design can balance the material degradation rate and bone growth rate, ensuring that new bone tissue can fill the degradation space in time while β-tricalcium phosphate degrades, thus ensuring the long-term structural strength and osseointegration stability of the prosthesis.

[0031] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0032] Figure 1 This is an axonometric view of the locatable 3D-printed elbow joint prosthesis structure of the present invention.

[0033] Figure 2 for Figure 1 Enlarged view of part A in the middle.

[0034] Figure 3 This is a top-view axonometric drawing of the locatable 3D-printed elbow joint prosthesis structure of the present invention.

[0035] Figure 4 This is a side cross-sectional view of the buffer sleeve in the positionable 3D-printed elbow joint prosthesis structure of the present invention.

[0036] Figure 5 This is an isometric view of the lower prosthesis in the 3D-printed elbow joint prosthesis structure that can be positioned according to the present invention.

[0037] Figure 6 This is a side sectional view of the sleeve in the positionable 3D-printed elbow joint prosthesis structure of the present invention.

[0038] Figure 7 for Figure 6 Enlarged view of section B.

[0039] The reference numerals in the accompanying drawings of the instruction manual include: 1. Upper prosthesis; 2. Lower prosthesis; 3. Fixed shaft; 4. Connecting rod; 5. Bracket; 6. Collar; 7. Limiting rod; 8. Buffer sleeve; 9. U-block; 10. Eccentric wheel; 11. Scale line; 12. Sleeve; 13. Screw; 14. Ring sleeve; 15. Engaging teeth. Detailed Implementation

[0040] The following detailed description illustrates the specific implementation method:

[0041] Implementation, for example, attached Figure 1 As shown: A positionable 3D-printed elbow joint prosthesis structure includes an upper prosthesis 1 and a lower prosthesis 2. The lower prosthesis 2 is made of a titanium alloy matrix material and coated with a hydroxyapatite coating. The upper prosthesis 1 is made of a porous titanium alloy core material with a porosity of 60% and a pore size of 300 μm. A connecting component is provided between the upper prosthesis 1 and the lower prosthesis 2 for connecting them.

[0042] Specifically, the porous titanium alloy core of the upper prosthesis 1 is also composited with bioactive ceramic particles, wherein the bioactive ceramic particles are β-tricalcium phosphate material with a particle size of 50μm and a volume fraction of 8% in the porous titanium alloy core.

[0043] Preoperatively, the shapes of the lower prosthesis 2 and upper prosthesis 1 were designed based on the patient's distal humerus anatomy, and the range of motion of the elbow joint was determined using preoperative imaging data. The lower prosthesis 2 and upper prosthesis 1 were then printed using SLM 3D printing technology, with the specific structures as follows:

[0044] Lower prosthesis 2: Printed using titanium alloy substrate material. During printing, a micron-level rough surface (roughness Ra5μm) is processed on the surface of the titanium alloy substrate material, and a hydroxyapatite coating (coating thickness 50μm) is applied to the surface of the lower prosthesis 2 using a sandblasting-spraying process.

[0045] Upper prosthesis 1: Printed using a porous titanium alloy core material (porosity 60%, pore size 300μm). Before printing, β-tricalcium phosphate particles (particle size 50μm, volume fraction 8%) are added to the porous titanium alloy core material. The 3D-printed "porous-particle composite" structure provides channels and nutritional support for bone cell growth. At the same time, two 2mm diameter osteointegration holes are reserved at the end of the upper prosthesis 1 that fits with the osteotomy surface to facilitate the ingrowth of autologous bone tissue.

[0046] like Figure 2 As shown, specifically, the connecting assembly includes a connector located at one end of the lower prosthesis 2. A fixed shaft 3 is fixedly connected to the connector by screws. A connecting rod 4 is hinged to the fixed shaft 3. The end of the connecting rod 4 away from the fixed shaft 3 and the end of the lower prosthesis 2 are fixedly connected by screws. The lower prosthesis 2 swings on the fixed shaft 3. The connector is provided with an adjustable positioning component for limiting the swing angle of the lower prosthesis 2.

[0047] The connector includes symmetrically detachable brackets 5 connected to one end of the upper prosthesis 1. A fixing shaft 3 passes through one of the brackets 5 and slides with it. The other bracket 5 is fixedly connected to one end of the fixing shaft 3 by screws. One of the brackets 5 has several scale lines 11 circumferentially opened on its side wall.

[0048] like Figure 2 , Figure 3 and Figure 5 As shown, specifically, the adjustable positioning component includes a collar 6 symmetrically and rotatably fitted onto the fixed shaft 3. In this embodiment, the fixed shaft 3 is provided with a limiting structure so that the collar 6 can only rotate on the fixed shaft 3 and cannot slide axially on the fixed shaft 3; one side wall of the collar 6 has several protruding teeth integrally formed circumferentially, and one side wall of the bracket 5 has several toothed grooves circumferentially opened, with the protruding teeth meshing with their adjacent toothed grooves. In this embodiment, Figure 2 There is a gap between the upper left collar 6 and the left bracket 5, so that the bracket 5 can slide on the fixed shaft 3. At the same time, when the gap exists, the convex tooth and the tooth groove do not mesh. A limit rod 7 is integrally formed between adjacent collars 6. The limit rod 7 is used to limit the rotation angle of the connecting rod 4.

[0049] A U-shaped block 9 is provided on one end of the fixed shaft 3. Both ends of the U-shaped block 9 are integrally formed with eccentric wheels 10, and the eccentric wheels 10 are eccentrically hinged to the side wall of the fixed shaft 3 adjacent to it.

[0050] Both the upper prosthesis 1 and the lower prosthesis 2 are equipped with positioning auxiliary components to assist in the installation of the upper prosthesis 1 and the lower prosthesis 2.

[0051] like Figure 6 and Figure 7 As shown, specifically, the positioning auxiliary components include sleeves 12, which are fitted onto the upper prosthesis 1 and the lower prosthesis 2. Each sleeve 12 contains a locking element for locking the upper prosthesis 1 and the lower prosthesis 2. In this embodiment, the locking element is a ring 14 integrally formed on the inner wall of the sleeve 12. Each ring 14 has several circumferentially formed interlocking teeth 15, with the ends of the interlocking teeth 15 away from the ring 14 being wedge-shaped. Each inner wall of the sleeve 12 has threads, and each thread is threaded with a screw 13. Each screw 13 has a channel, and both the upper prosthesis 1 and the lower prosthesis 2 slide with their adjacent channels. The edges of the channels on the screw 13 located inside the sleeve 12 are inclined, with the inclined surface facing the center of the screw 13 axis, and the inclined surface matches the wedge-shaped surface of the interlocking teeth 15. Each side wall of the sleeve 12 has several through holes.

[0052] In this embodiment, the specific installation steps of the elbow joint prosthesis structure are as follows:

[0053] Step 1, biological fixation installation of sleeve 12:

[0054] Combination Figure 1 As shown, during the surgery, the patient was placed in a supine position under general anesthesia, with the affected limb abducted and fixed at 90°. An incision was made along the posterior aspect of the elbow joint to expose the ulnar nerve, which was then covered with a protective sheath. Diseased synovium, osteophytes, and damaged cartilage within the elbow joint were removed until a fresh bone wound surface was exposed.

[0055] The distal humerus is osteotomized to a predetermined depth, and the osteotomy surface is roughened. The proximal ulna is osteotomized between the coronoid process and the olecranon, with the osteotomy surface at an angle of 12-15° to the long axis of the ulna, to ensure that it matches the shape of the inner wall of the cannula 12.

[0056] Remove the cannula 12 from the upper prosthesis 1, align the cannula 12 with the distal osteotomy surface of the patient's humerus, and slowly insert the cannula 12 until it completely fits the inner wall of the osteotomy surface. Confirm with the navigation system that the deviation between the central axis of the cannula 12 and the central axis of the humerus is ≤0.5°.

[0057] The space between the outer wall of the cannula 12 and the humeral bone wall (0.2-0.3 mm) is filled with autologous bone marrow fluid (preoperative centrifuged bone marrow stromal stem cell suspension, dose 5-8 ml). At the same time, two 3 mm diameter titanium alloy locking screws are obliquely screwed into the osteointegration hole of the cannula 12 (the screws penetrate the cannula 12 and enter the humeral cortical bone 2-3 mm). The distance between adjacent locking screws is ≥10 mm to avoid stress concentration.

[0058] After fixation, gently tap the top of sleeve 12 with a bone hammer and listen to the sound to judge the stability (a crisp sound indicates reliable fixation). If there is looseness, it is necessary to add autologous bone particles and add a locking screw for fixation.

[0059] The cannula 12 on the lower prosthesis 2 is attached to the proximal osteotomy surface of the patient's ulna. After filling with bone marrow fluid, a titanium alloy locking screw is inserted through the cannula 12 and screwed into the cortical bone of the ulna. The length of the locking screw is such that it does not penetrate the cortex on the opposite side of the ulna.

[0060] The sleeve 12 is ensured to be free from forward, backward, left, or right displacement. If there is a small gap between the sleeve 12 and the osteotomy surface, a small amount of bone cement can be filled in (only for temporary auxiliary fixation, and will not affect the biological fixation effect after the bone integration is completed).

[0061] Step 2, Implantation of the prosthesis and installation of the connection components:

[0062] Combination Figure 1 and Figure 2 As shown, the upper prosthesis 1 was removed, and a thin layer of bone morphogenetic protein gel (BMP-2, concentration 0.5mg / ml) was evenly applied to the surface of the upper prosthesis 1. It was then slowly inserted into the humeral cannula 12. The lower prosthesis 2 was implanted in the same manner. After implantation, X-rays were used to confirm that the positions of the upper prosthesis 1 and the lower prosthesis 2 were not misaligned.

[0063] Lock the left end of the support 5 and the upper prosthesis 1 with titanium alloy screws, and lock the left end of the lower prosthesis 2 and the right end of the connecting rod 4 with titanium alloy screws. The torque of the titanium alloy screws should be controlled at 10-12N. m.

[0064] Step 3, limit angle adjustment:

[0065] The elbow joint range of motion data was obtained, and the patient's elbow joint angle was determined based on the elbow joint range of motion data.

[0066] Combination Figure 2As shown, in this embodiment, the initial orientation of the horizontal end of the U-shaped block 9 is to the left. Because there is a gap between the collar 6 near the eccentric wheel 10 and its adjacent support 5, the support 5 can slide on the fixed shaft 3. Simultaneously, when the gap exists, the convex tooth and the tooth groove are not engaged, allowing the collar 6 to rotate on the fixed shaft 3. When it is necessary to reduce the elbow joint's range of motion, the limiting rod 7 is turned counterclockwise, reducing the angle between the limiting rod 7 and the upper prosthesis 1. At this time, the maximum range of motion between the connecting rod 4 and the upper prosthesis 1 decreases accordingly. When it is necessary to increase the elbow joint's range of motion, the limiting rod 7 is turned clockwise, increasing the angle between the limiting rod 7 and the upper prosthesis 1. At this time, the maximum range of motion between the connecting rod 4 and the upper prosthesis 1 increases accordingly.

[0067] After adjusting the limiting rod 7 to the appropriate angle, turn the U-shaped block 9 counterclockwise so that its horizontal end faces the desired direction. Figure 2 As shown above, the U-shaped block 9 drives the eccentric wheel 10 to rotate counterclockwise on the fixed shaft 3. Since the eccentric wheel 10 is eccentrically hinged to the fixed shaft 3, the eccentric wheel 10 can push the adjacent bracket 5 to the right. At this time, the bracket 5 moves to the right, causing the tooth groove on the bracket 5 to mesh with the convex tooth on the collar 6. At this time, the collar 6 cannot rotate, so that the position of the limiting rod 7 is fixed, thereby achieving the locking of the swing angle of the lower prosthesis 2 and avoiding excessive movement after surgery.

[0068] For example, if the patient's maximum safe flexion angle during surgery is 130°, then rotate the limit rod 7 to the 130° mark on the scale 11, and then bend the U-shaped block 9 to engage and lock the teeth. After locking, use a torque wrench to check the engagement strength (torque ≥ 8N). m), to prevent postoperative displacement of the limiting rod 7.

[0069] Step 4, Implant Locking:

[0070] Combination Figure 6 and Figure 7 As shown, after the lower prosthesis 2 and the upper prosthesis 1 are respectively inserted into the sleeve 12, the corresponding screws 13 are turned with a torque wrench to complete the initial fixation. Specifically, since the screw 13 is threaded into the inner wall of the sleeve 12, when the screw 13 is turned, the screw 13 moves upward along the axial direction of the sleeve 12. At this time, the inclined surface of the channel edge of the screw 13 contacts the wedge-shaped surface of the engagement teeth 15 on the ring sleeve 14 and generates a squeezing effect. As the screw 13 continues to advance, the inclined surface transmits the radial force to the engagement teeth 15, causing all the engagement teeth 15 to contract towards the center of the sleeve 12. At this time, the engagement teeth 15 can tightly engage the rough surfaces of the lower prosthesis 2 and the upper prosthesis 1, achieving a rigid connection between the prosthesis and the sleeve 12 through mechanical engagement. In this process, the wedge-shaped design of the engagement teeth 15 can efficiently convert the axial thrust of the screw 13 into radial clamping force, ensuring that the torque reaches 15-18N. m.

[0071] Meanwhile, the through-holes on the sidewall of cannula 12 provide a channel for postoperative bone tissue ingrowth. When bone cells grow through the through-holes to the gap between cannula 12 and the prosthesis, they will bio-integrate with the hydroxyapatite coating of the lower prosthesis 2 and the β-tricalcium phosphate particles of the upper prosthesis 1, forming a dual fixation system of "mechanical locking + biofusion", which significantly improves the long-term stability of the prosthesis. This completes the entire fixation process of the prosthesis.

[0072] like Figure 4 As shown, specifically, a buffer assembly is provided at the connection between the connecting rod 4 and the upper prosthesis 1.

[0073] The cushioning assembly includes a cushioning sleeve 8 that is fixedly connected to one end of the upper prosthesis 1 by screws. A cushioning spring is provided inside the cushioning sleeve 8. One end of the cushioning spring is fixedly connected to the upper prosthesis 1 by screws, and the other end of the cushioning spring is fixedly connected to the connecting rod 4 by screws.

[0074] The buffer spring absorbs some of the impact force during elbow joint movement. If the patient exerts force unexpectedly or the range of motion suddenly increases, the elastic deformation of the buffer spring can buffer the force at the connection between the connecting rod 4 and the upper prosthesis 1, preventing local stress concentration that could lead to prosthesis or bone damage. In this embodiment, the bracket 5, fixing shaft 3, collar 6, and connecting rod 4 are all made of pure titanium, with anodized surfaces forming a titanium oxide film (10nm thick) to improve biocompatibility and prevent postoperative rejection. The buffer spring is woven from titanium alloy wire and also anodized to ensure no metal ion release upon contact with bodily fluids. The inner wall of the buffer sleeve 8 is coated with a polyetheretherketone (PEEK) coating with a thickness of 0.1-0.2mm to reduce frictional wear between the buffer spring and the sleeve. Simultaneously, the biocompatibility of the PEEK material prevents local tissue irritation.

[0075] This invention utilizes SLM 3D printing technology combined with preoperative imaging data to design the prosthesis shape, achieving a high degree of fit between the upper prosthesis 1 and the lower prosthesis 2 and the distal humerus and proximal ulna, respectively. Compared to existing partially customized prostheses, this method offers higher fitting accuracy, reduces the gap between the prosthesis and bone tissue, lowers the risk of postoperative prosthesis micromovement, and lays the foundation for long-term stable use. The adjustable positioning component can flexibly adjust the limiting angle according to the patient's individual elbow joint range of motion data, breaking the limitations of existing prosthesis fixation structures. It can match the postoperative activity needs of different patients, effectively avoiding prosthesis loosening or damage due to excessive activity, and improving postoperative safety and patient fit.

[0076] Meanwhile, this invention uses a biological fixation method (relying on the osseointegration of the hydroxyapatite coating on the surface of the upper prosthesis 1 with the bone tissue) to install the prosthesis. Combined with the structural advantages of 3D printed prostheses, it can promote osseointegration between the prosthesis and autologous bone. Compared with traditional bone cement fixation, it reduces problems such as bone cement aging and loosening, and extends the service life of the prosthesis. Each part of the structure is detachable, which reduces the difficulty for doctors to install the prosthesis, and also facilitates operation if the prosthesis position needs to be adjusted or maintained after surgery.

[0077] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A positionable 3D-printed elbow joint prosthesis structure, comprising an upper prosthesis (1) and a lower prosthesis (2), characterized in that, A connecting component for connecting the upper prosthesis (1) and the lower prosthesis (2) is provided between the upper prosthesis (1) and the lower prosthesis (2); The connecting assembly includes a connector located at one end of the lower prosthesis (2), a fixed shaft (3) is fixedly connected to the connector, a connecting rod (4) is hinged to the fixed shaft (3), the end of the connecting rod (4) away from the fixed shaft (3) is fixedly connected to the end of the lower prosthesis (2), and the lower prosthesis (2) swings on the fixed shaft (3); The connector is equipped with an adjustable positioning component for limiting the swing angle of the lower prosthesis (2).

2. The positionable 3D-printed elbow joint prosthesis structure according to claim 1, characterized in that, The connector includes a bracket (5) symmetrically and detachably connected to one end of the upper prosthesis (1), a fixing shaft (3) passing through one of the brackets (5) and slidingly engaging with the bracket (5), and the other bracket (5) being fixedly connected to one end of the fixing shaft (3).

3. The positionable 3D-printed elbow joint prosthesis structure according to claim 2, characterized in that, The adjustable positioning assembly includes collars (6) that are symmetrically and rotatably fitted on a fixed shaft (3). One of the collars (6) has several protruding teeth fixedly connected to one side wall in the circumferential direction, and one of the brackets (5) has several toothed grooves opened in the circumferential direction on one side wall. The protruding teeth all mesh with their adjacent toothed grooves. A limiting rod (7) is fixedly connected between adjacent collars (6). The limiting rod (7) is used to limit the rotation angle of the connecting rod (4). A U-shaped block (9) is provided on one end of the fixed shaft (3). Both ends of the U-shaped block (9) are fixedly connected to eccentric wheels (10). The eccentric wheels (10) are eccentrically hinged to the side wall of the fixed shaft (3) adjacent to it.

4. The positionable 3D-printed elbow joint prosthesis structure according to claim 3, characterized in that, One of the brackets (5) has several scale lines (11) on its side wall facing outwards.

5. The positionable 3D-printed elbow joint prosthesis structure according to claim 4, characterized in that, Both the upper prosthesis (1) and the lower prosthesis (2) are provided with positioning auxiliary components to assist in the installation of the upper prosthesis (1) and the lower prosthesis (2); The positioning auxiliary components include sleeves (12), which are fitted onto the upper prosthesis (1) and the lower prosthesis (2). Each sleeve (12) is provided with a locking element for locking the upper prosthesis (1) and the lower prosthesis (2).

6. The positionable 3D-printed elbow joint prosthesis structure according to claim 5, characterized in that, Several through holes are opened on the side wall of the sleeve (12).

7. The positionable 3D-printed elbow joint prosthesis structure according to claim 6, characterized in that, The lower prosthesis (2) is made of titanium alloy matrix material and is coated with hydroxyapatite coating.

8. The positionable 3D-printed elbow joint prosthesis structure according to claim 7, characterized in that, The upper prosthesis (1) is made of porous titanium alloy core material with a porosity of 60%-70% and a pore size of 300-500μm.

9. The positionable 3D-printed elbow joint prosthesis structure according to claim 8, characterized in that, A buffer assembly is provided at the connection between the connecting rod (4) and the upper prosthesis (1); The buffer assembly includes a buffer sleeve (8) fixedly connected to one end of the upper prosthesis (1), and a buffer spring is provided inside the buffer sleeve (8). One end of the buffer spring is fixedly connected to the upper prosthesis (1), and the other end of the buffer spring is fixedly connected to the connecting rod (4).

10. The positionable 3D-printed elbow joint prosthesis structure according to claim 9, characterized in that, The porous titanium alloy core of the upper prosthesis (1) is also composited with bioactive ceramic particles, wherein the bioactive ceramic particles are β-tricalcium phosphate material, the particle size of β-tricalcium phosphate material is 50-100μm, and the volume fraction in the porous titanium alloy core is 8%-12%.

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