A constrained ball and socket arrangement for the ulna or radius

Abstract

This invention provides a restrictive ball-and-socket structure for the ulna or radius, belonging to the field of prosthetic technology. The invention includes: a metal connecting structure, one end for connection to the articular surface; a ball-and-socket joint, the other end of which is embedded; and a ball-and-socket osteotomy segment, one end having a ball head embedded within the ball-and-socket joint and movable within it, the other end of which is connected to the ulna or radius prosthesis. By using a restrictive ball-and-socket structure to replace the traditional sleeve-stretch structure, this invention effectively improves the overall stress pattern of the prosthesis, avoids long-term complications such as postoperative joint deformities, prosthesis loosening and wear, and significantly improves the long-term clinical outcomes of reconstruction for long ulna or radius defects.

Description

Technical Field

[0001] This invention relates to the field of artificial prosthesis technology, and more particularly to a restrictive ball-and-socket structure for the ulna or radius. Background Technology

[0002] For the clinical need to reconstruct long ulnar / radial bone defects involving the superior or inferior radioulnar joints, current clinical protocols have the following clear shortcomings: Existing prostheses mostly employ a sleeve-stretching structure to match joint movement. In this structure, the outer sleeve and the inner axis can rotate relative to each other around a central axis, restoring the forearm's rotational function. The outer sleeve and the inner axis can also slide and stretch relative to each other axially, allowing the prosthesis to lengthen as the forearm grows and develops. However, this structure lacks stability under long-term axial pressure after surgery, potentially leading to prosthesis shortening. Uneven stress on the prosthesis during long-term use can cause wear and loosening, and in severe cases, can induce secondary deformities of the wrist and elbow joints, resulting in poor long-term reconstruction outcomes. This is illustrated by utility model patents with authorization publication numbers CN221556142U, CN221556143U, CN216628827U, and CN221556144U. Summary of the Invention

[0003] In view of this, to address the aforementioned shortcomings of existing prostheses that mostly employ a sleeve-stretching structure, this invention provides a restrictive ball-and-socket structure for the ulna or radius. By replacing the traditional sleeve-stretching structure with a restrictive ball-and-socket structure, the overall stress pattern of the prosthesis is effectively improved, avoiding long-term complications such as postoperative joint deformities, prosthesis loosening and wear, and significantly enhancing the long-term clinical outcomes of long-segment ulnar or radial defect reconstruction.

[0004] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a restrictive ball-and-socket structure for the ulna or radius, comprising: A metal connection structure, one end of which is used to connect to the joint surface; A ball socket is embedded at the other end of the metal connection structure; The ball-and-socket osteotomy segment has a ball head at one end that is embedded in the ball socket and can move within the ball socket, and the other end of the ball-and-socket osteotomy segment is connected to the ulna or radius prosthesis.

[0005] Preferably, the ball socket is made of polyethylene.

[0006] Preferably, the articulated surface is made of polyethylene.

[0007] Preferably, the other end of the ball-and-socket osteotomy segment is conically connected to the ulna or radius prosthesis.

[0008] Compared with the prior art, the present invention has the following beneficial effects: The restrictive ball-and-socket structure of the present invention adopts a movable fit structure formed by the ball head embedding into the ball socket, replacing the traditional sleeve tension joint connection structure. It optimizes the line contact force mode of the original sleeve structure into the surface contact force mode of the ball-and-socket structure, effectively dispersing the prosthesis load and avoiding prosthesis wear and loosening caused by local stress concentration. It solves the mechanical failure problem that traditional prostheses are prone to after long-term use from a structural level.

[0009] The ball head can achieve multi-directional physiological movement within the ball socket, accurately replicating the original rotation and flexion-extension range of motion of the superior or inferior radioulnar joint. At the same time, the restrictive padding structure can avoid the risk of joint dislocation, ensuring postoperative joint function and solving the technical problem of difficulty in balancing range of motion and stability in traditional structures, thus reducing the risk of secondary deformities of the wrist and elbow joints after surgery. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the overall assembly structure of the present invention; Figure 2 This is an exploded view of the present invention; Figure 3 This is a schematic diagram of the proximal radial prosthesis of the present invention; Figure 4 This is a schematic diagram of the present invention used in a full ulna prosthesis; Figure 5 This is a schematic diagram of the present invention used in a distal ulna prosthesis; Figure 6 This is a schematic diagram of the present invention used in a total radial prosthesis.

[0011] In the diagram, 1. Metal connection structure; 2. Ball socket; 3. Ball socket osteotomy segment; 4. Ball head; 5. Articular surface. Detailed Implementation

[0012] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0013] like Figure 1-2 As shown, the present invention provides a restrictive ball-and-socket structure for the ulna or radius, comprising: Metal connection structure 1, one end of which is used to connect to joint surface 5; The ball socket 2 is embedded at the other end of the metal connection structure 1; The ball-and-socket osteotomy segment 3 has a ball head 4 at one end that is embedded in the ball socket 2 and can move within the ball socket 2. The other end of the ball-and-socket osteotomy segment 3 is connected to the ulna or radius prosthesis.

[0014] In this technical solution, the ball socket 2 and the articular surface 5 are fixedly connected through a metal connecting structure 1. The ball head 4 at one end of the osteotomy segment 3 of the ball socket is embedded in the ball socket 2 to form a movable fit, while the other end is connected to the ulnar or radial prosthesis. This allows the prosthesis side to simulate the physiological movement of the original radioulnar joint through the movement of the ball head 4 within the ball socket 2. By replacing the traditional sleeve-type line contact connection with the surface contact fit of the ball socket 2, the stress on the prosthesis is distributed, avoiding wear and loosening problems caused by local stress concentration. At the same time, it ensures the range of motion of the joint while preventing joint dislocation through the limiting effect of the ball socket, thus solving the defect of traditional structures that cannot simultaneously achieve stability and range of motion.

[0015] In this invention, the socket 2 is made of polyethylene. Utilizing the low coefficient of friction and high biocompatibility of polyethylene, the frictional resistance of the ball head 4 during its movement within the socket 2 is reduced, while simultaneously minimizing metal foreign body reactions. This significantly reduces the wear rate between the ball head 4 and the socket 2, extending the prosthesis's lifespan. Furthermore, the excellent biocompatibility of polyethylene reduces the risk of postoperative local inflammatory reactions.

[0016] In this invention, the articular surface 5 is made of polyethylene, forming a low-friction fit with the native bone / corresponding articular cartilage, simulating the contact characteristics of the native articular surface. This reduces wear and tear on the prosthesis articular surface from the native bone tissue or articular cartilage, lowers the probability of postoperative degenerative changes in adjacent joints, and improves the compatibility between the prosthesis and the native tissue.

[0017] In this invention, the other end of the ball-and-socket osteotomy segment 3 is conically connected to the ulnar or radial prosthesis. For example, multiple prosthesis components can be connected via a conical connection structure. Alternatively, the ball-and-socket osteotomy segment and the ulnar / radial prosthesis can be connected via an interference fit of conical surfaces, relying on the friction between the conical surfaces to achieve self-locking fixation after assembly. Stable connection of the prosthesis components can be achieved without additional auxiliary fixation devices, simplifying assembly. Furthermore, the conical connection offers greater adaptability, accommodating different models of ulnar / radial prostheses and improving the flexibility of clinical use.

[0018] The technical solution of the present invention will be described below with reference to specific embodiments.

[0019] Example 1 Suitable for proximal radial prostheses, such as Figure 3 As shown.

[0020] In this embodiment 1, a restricted ball-and-socket structure is used instead of the radial stem assembly in the utility model with authorization announcement number CN221556142U.

[0021] Specifically: A proximal radius prosthesis for reconstructing proximal radius defects includes a radial restrictive ball-and-socket structure and a radial stem assembly. The restrictive ball-and-socket structure is designed based on the patient's proximal radius shape and includes a metal connecting structure 1, one end of which connects to a polyethylene articular surface 5; a polyethylene ball-and-socket joint 2, embedded at the other end of the metal connecting structure 1; and a ball-and-socket osteotomy segment, one end of which has a ball head 4 embedded within the polyethylene ball-and-socket joint 2 and is movable within the polyethylene ball-and-socket joint. The other end of the ball-and-socket osteotomy segment is interference-fitted with the conical surface of the radial stem assembly.

[0022] The restrictive ball-and-socket structure consists of a polyethylene articular surface 5, a metal connecting structure 1, a polyethylene ball-and-socket joint 2, and a ball-and-socket osteotomy segment 3. The proximal end of the polyethylene articular surface forms the humeroradial articular surface, suitable for forming the humeroradial joint with the head of the humerus, and the distal end is fixed to the metal connecting structure 1. The metal connecting structure 1 has several suture holes suitable for suturing the annular ligament and biceps brachii tendon to it. The other end of the metal connecting structure 1 accommodates the polyethylene ball-and-socket joint 2. The polyethylene ball-and-socket joint 2 contains the head of the ball-and-socket osteotomy segment 3. The ball-and-socket osteotomy segment 3 and the metal connecting structure 1 can rotate relative to each other about their axis. The other end of the ball-and-socket osteotomy segment 3 is connected to the radial stem.

[0023] The proximal radius prosthesis provided by this invention is installed as follows: the articular surface made of polyethylene, the metal connecting structure, the ball-and-socket joint made of polyethylene, the osteotomy segment of the ball-and-socket joint, and the radial stem are assembled. Then, the radial stem is fixed in the residual medullary cavity of the distal radius; finally, the annular ligament and the biceps brachii tendon are sutured to the metal connecting structure 1 through the suture hole with suture thread, thus completing the prosthesis installation.

[0024] Example 2 Suitable for full ulna prostheses, such as Figure 4 As shown.

[0025] This embodiment replaces the connection of the distal radioulnar joint prosthesis in the utility model with a restrictive ball-and-socket structure instead of the connection in the utility model with authorization announcement number CN216628827U.

[0026] A complete ulnar prosthesis for reconstructing a complete ulnar defect is a modular structure consisting of three parts: the proximal component—the ulnar semi-elbow joint prosthesis; the intermediate component—the defect segment; and the distal component—the distal radioulnar joint prosthesis. The articular surface shape of the ulnar semi-elbow joint prosthesis matches the articular surface shape of the humerus for distal articulation. Several suture holes are provided at the olecranon and coronoid processes of the ulnar semi-elbow joint prosthesis for reconstructing the joint capsule and tendons, thus ensuring elbow joint stability and flexion-extension dynamics. The proximal end of the defect segment connects to the distal end of the ulnar semi-elbow joint prosthesis, and the distal end connects to the distal radioulnar joint prosthesis. The distal radioulnar joint prosthesis is designed based on the shape of the patient's distal ulna and consists of a polyethylene articular surface 5, a metal connecting structure 1, a polyethylene ball-and-socket joint 2, and a ball-and-socket osteotomy segment 3. The polyethylene articular surface 5 is fixed to the metal connecting structure 1. The metal connecting structure 1 has several suture holes suitable for suturing the ulnar collateral ligament of the wrist joint to the metal connecting structure. The other end of the metal connecting structure 1 accommodates a polyethylene ball-and-socket joint 2. Simultaneously, the metal connecting structure 1 has several pin channels suitable for fixation to the ulnar side of the distal radius, fusing and fixing it to the distal radius. The polyethylene ball-and-socket joint 2 contains the small head (ball head 4) of the ball-and-socket osteotomy segment 3. The ball-and-socket osteotomy segment 3 and the metal connecting structure 1 can rotate relative to each other around an axis. The other end of the ball-and-socket osteotomy segment 3 connects to the defect segment. This invention can simultaneously achieve three functions: hemi-elbow joint reconstruction, distal radioulnar joint fusion, and forearm rotation.

[0027] The metal connection structure of the distal radioulnar joint prosthesis and the bone contact surface of the radius are 3D printed porous structures with a pore size of 400-600μm and a porosity of 50%-70%, which provides space for the ingrowth of new bone tissue. This allows the new bone tissue to crawl into the porous structure, thereby achieving the fusion of the distal radioulnar joint through bone ingrowth.

[0028] The ulnar semi-elbow joint prosthesis is designed based on the shape of the proximal ulna of the patient, that is, it is designed by simulation using DICOM data from CT scans of the patient's two upper limbs, so as to ensure that the articular surface of the ulnar semi-elbow joint prosthesis is perfectly matched with the patient's own humerus.

[0029] The manufacturing and usage process of a total ulnar prosthesis used to reconstruct a total ulnar defect is as follows: (a) Material preparation: This includes DICOM data from CT scans of the patient's two upper limbs, CAD software, electron-beammelting (EBM) 3D printing equipment, Ti6Al4V alloy raw materials, and polyethylene materials.

[0030] (II) Prosthesis Design Process: Design of the proximal component: Using CAD software to read the above DICOM data, the contralateral ulna is mirrored to obtain the proximal shape of the ulna. The size of the articular surface remains unchanged, while the width and thickness of the bone are reduced by 20%. The distal end of the ulnar semi-elbow joint prosthesis is designed as a concave tapered structure. Suture holes are left at the olecranon and coronoid processes of the ulnar semi-elbow joint prosthesis.

[0031] Design of distal components: The shape of the radial-ulnar fusion surface is designed based on CT data so that it can match the ulnar side of the radius after installation. The fusion surface has a porous structure with a pore size of 400-600μm and a porosity of 50%-70%. Two screw holes are left on the metal connection structure, and two suture holes are left at the very end of the metal connection structure.

[0032] (III) Prosthesis Production: The ulnar semi-elbow joint prosthesis and the distal radioulnar joint prosthesis were fabricated using EBM 3D printing technology, while the polyethylene liner was fabricated using traditional processes.

[0033] (iv) Prosthesis installation steps: After assembling the ulnar semi-elbow joint prosthesis, the defect segment, and the distal radioulnar joint prosthesis, the elbow joint capsule, the annular ligament of the radius, and the triceps brachii tendon are sutured to the suture holes of the ulnar semi-elbow joint prosthesis. Then, the metal connecting structure is fixed to the distal ulnar side of the radius with screws through the pre-drilled holes. Finally, the ulnar wrist joint capsule is sutured to the suture holes of the metal connecting structure, thus completing the installation of the full ulnar prosthesis.

[0034] Example 3 Suitable for distal ulna prostheses, such as Figure 5 As shown.

[0035] This embodiment replaces the distal radioulnar joint fusion component in the utility model with authorization announcement number CN221556143U with a restricted ball-and-socket structure.

[0036] A distal ulna prosthesis for reconstructing distal ulna defects includes a distal radioulnar joint prosthesis and an ulnar stem assembly. The distal radioulnar joint prosthesis is designed based on the patient's distal ulna shape and consists of a polyethylene articular surface 5, a metal connecting structure 1, a polyethylene ball-and-socket joint 2, and a ball-and-socket osteotomy segment 3. The polyethylene articular surface 5 is fixed to the metal connecting structure 1. The metal connecting structure 1 has several suture holes suitable for suturing the ulnar collateral ligament of the wrist joint to the metal connecting structure 1. The other end of the metal connecting structure 1 accommodates the polyethylene ball-and-socket joint 2. Simultaneously, the metal connecting structure 1 has several pin channels suitable for fixation to the ulnar side of the distal radius, fusing and fixing it to the distal radius. The polyethylene ball-and-socket joint 2 contains the small head (ball head 4) of the ball-and-socket osteotomy segment 3. The ball-and-socket osteotomy segment 3 and the metal connecting structure 1 can rotate relative to each other about an axis. The other end of the ball-and-socket osteotomy segment is connected to the ulnar stem.

[0037] The ulnar intramedullary stalk is either a 3D-printed porous stalk or a non-cemented stalk coated with hydroxyapatite.

[0038] The radial side of the metal connection structure 1 is a 3D printed porous structure with a pore size of 400-600μm and a porosity of 50%-70%. The porous structure is beneficial to bone ingrowth and the formation of long-lasting wrist joint fusion.

[0039] The installation process of the proximal radius prosthesis provided by this invention is as follows: The articular surface 5 (made of polyethylene), the metal connecting structure 1, the ball-and-socket joint 2 (made of polyethylene), the osteotomy segment 3 of the ball-and-socket joint, and the ulnar stem are assembled. Then, the ulnar stem is fixed in the residual medullary cavity of the proximal ulna. Finally, the metal connecting structure 1 is fixed to the ulnar side of the distal radius with cortical screws through the screw channel. At the same time, the ulnar collateral ligament of the wrist joint is sutured to the metal connecting structure 1 with sutures through the suture hole, thus completing the prosthesis installation.

[0040] Example 4 Suitable for total radial prosthesis, such as Figure 6 As shown.

[0041] This embodiment replaces the distal radius wrist joint fusion component in the utility model with authorization announcement number CN221556144U with a restricted ball-and-socket structure.

[0042] Specifically: This invention provides a total radial prosthesis for reconstructing a total radial defect, comprising a restrictive ball-and-socket structure, a defect segment, and a distal radial wrist joint fusion assembly. The restrictive ball-and-socket structure consists of a polyethylene articular surface 5, a metal connecting structure 1, a polyethylene ball-and-socket joint 2, and a ball-and-socket osteotomy segment 3. The proximal end of the polyethylene articular surface 5 forms a humeroradial articular surface adapted to form a humeroradial joint with the capitulum of the humerus, and the distal end is fixed to the metal connecting structure 1. The metal connecting structure 1 has several suture holes suitable for suturing the annular ligament and biceps brachii tendon to the metal connecting structure. The other end of the metal connecting structure 1 accommodates the polyethylene ball-and-socket joint 2. The polyethylene ball socket 2 contains the small head (ball head 4) of the ball socket osteotomy segment 3. The ball socket osteotomy segment 3 and the metal connection structure 1 can rotate relative to each other around the axis. The other end of the ball socket osteotomy segment 3 is connected to the defect segment. The distal radius wrist fusion assembly is designed based on the shape of the patient's distal radius, and its distal articular surface matches the articular surface of the proximal row of carpal bones. The distal radius wrist fusion assembly has several pin channels suitable for fixation with the radius and carpal bones. At the same time, the distal radius wrist fusion assembly has several suture holes suitable for suturing the distal radioulnar joint capsule and ligament to the distal radius wrist fusion assembly. The proximal end of the distal radius wrist fusion assembly has a conical groove adapted to the defect segment. The distal radius wrist fusion assembly is conically assembled with the defect segment.

[0043] The installation process of the total radial prosthesis provided by this invention is as follows: First, the restrictive ball-and-socket structure, the defect segment, and the distal radius wrist joint fusion component are assembled. Then, the distal radius wrist joint fusion component is fixed to the radius and carpal bones with cortical screws to achieve functional fusion of the wrist joint. Finally, the annular ligament and biceps tendon are sutured to the metal connection structure 1 through the suture hole with sutures, thus completing the prosthesis installation.

[0044] The above description is merely a preferred embodiment of the present invention. However, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention should be covered within the scope of protection of the present invention.

Claims

1. A constrained ball and socket structure for the ulna or radius, characterized by, include: A metal connection structure, one end of which is used to connect to the joint surface; A ball socket is embedded at the other end of the metal connection structure; The ball-and-socket osteotomy segment has a ball head at one end that is embedded in the ball socket and can move within the ball socket, and the other end of the ball-and-socket osteotomy segment is connected to the ulna or radius prosthesis.

2. A restrictive ball-and-socket structure for the ulna or radius according to claim 1, characterized in that, The ball socket is made of polyethylene.

3. The restrictive ball-and-socket structure for the ulna or radius according to claim 1, characterized in that, The articulated surfaces are made of polyethylene.

4. A restrictive ball-and-socket structure for the ulna or radius according to any one of claims 1-3, characterized in that, The other end of the ball-and-socket osteotomy segment is connected to the ulna or radius prosthesis via a conical fitting.

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