Artificial wrist joint

Abstract

The invention discloses an artificial wrist joint, comprising a distal carpal bone fixing piece, a distal joint fossa plugged into the distal carpal bone fixing piece, a distal joint head arranged in the distal joint fossa, the distal joint head plugged into one end of a connecting piece, the other end of the connecting piece plugged into a proximal joint head, the proximal joint head arranged in the proximal joint fossa, a proximal radius fixing piece plugged into the bottom of the proximal joint fossa, and screws threadedly connected to the distal carpal bone fixing piece and the proximal radius fixing piece. The artificial wrist joint of the invention solves the problems of instability and poor mobility of existing artificial wrist joints.

Description

Technical Field

[0001] The invention belongs to the technical field of medical implants and relates to an artificial wrist joint. Background Art

[0002] The only treatment option for end-stage wrist osteoarthritis, if achieving a movable joint, is joint replacement. Due to the complex structure of the human wrist joint, involving multi-dimensional rotation and multi-joint linkage, the wrist bones themselves exhibit a wide range of motion and complex forces. Existing prosthetic technologies have limited technical solutions. Failure to address these issues can easily lead to two problems: loosening of the prosthesis and suboptimal joint mobility. This has hindered widespread clinical application of artificial wrist joints. Summary of the Invention

[0003] The purpose of the present invention is to provide an artificial wrist joint to solve the problems of existing artificial wrist joints such as unsatisfactory range of motion, easy loosening and easy dislocation of connecting parts.

[0004] The technical solution adopted by the present invention is that the artificial wrist joint includes a distal carpal bone fixer, a distal articular fossa is inserted into the distal carpal bone fixer, a distal articular head is arranged in the distal articular fossa, the distal articular head is inserted into one end of the connecting piece, and the other end of the connecting piece is inserted into the proximal articular head, the proximal articular head is arranged in the proximal articular fossa, and a proximal radius fixer is inserted into the bottom of the proximal articular fossa, and threaded holes are provided on the distal carpal bone fixer and the proximal radius fixer, and screws are threaded in the threaded holes.

[0005] The present invention is also characterized in that

[0006] The distal carpal bone fixation piece is in the shape of a "human", including a first carpal bone fixation plate, one end of the first carpal bone fixation plate is connected to one end of the second carpal bone fixation plate, the first carpal bone fixation plate and the second carpal bone fixation plate form a "human" shape, and the first carpal bone fixation plate and the second carpal bone fixation plate are both provided with a plurality of first protrusions and a plurality of threaded screw holes, and screws are provided in the screw holes.

[0007] The distal joint socket comprises a first base, a bottom of the first base is provided with a plurality of first grooves, the first grooves are plugged with the first protrusions, and a spherical joint socket is provided on the first base.

[0008] The distal joint head includes a truncated spherical first joint head, and a first connecting groove is provided from the truncated surface of the first joint head to the center of the circle. The first joint head cooperates with the joint socket and can rotate in the joint socket. The first connecting groove is plugged into the connecting piece and the connecting piece can move up and down in the first connecting groove.

[0009] The depth of the fossa is greater than the radius of the first articular head. The volar edge of the fossa to the volar top edge of the first base and the dorsal edge of the fossa to the dorsal top edge of the first base are both set to a wavy slope A. The setting of the slope A, the radius of the first articular head, and the depth of the fossa are adapted to the ergonomic structure of the middle wrist joint and conform to the physiological range of flexion and extension of the middle wrist joint.

[0010] The proximal joint head includes a truncated spherical ulnar joint head, a second connecting groove is provided from the truncated surface of the ulnar joint head to the center of the circle, the second connecting groove is connected to the connecting piece, a spherical radial joint head is provided on the side of the ulnar joint head away from the ulna, the radius of the ulnar joint head is larger than the radius of the radial joint, and an ulnar section is provided on the side of the ulnar joint head close to the triangular bone, and the ulnar section is adapted to the triangular bone.

[0011] The depth of the second connection groove is greater than the radius of the ulnar head. The centers of the ulnar and radial heads are located in the same horizontal plane and do not overlap. The radii and curvature radii of the ulnar and radial heads, as well as the height of the ulnar head, are designed to align with the ergonomic structure of the radiocarpal joint and the physiological range of motion of the wrist. A cut surface is provided on the ulnar side of the ulnar head to accommodate the triquetrum.

[0012] The proximal fossa includes a second base, a plurality of second grooves are provided at the bottom of the second base, an ulnar fossa is provided on the second base, a radial fossa is provided on the side of the ulnar fossa away from the ulna, the ulnar fossa is connected to the radial fossa, the ulnar fossa cooperates with the ulnar articular head and the ulnar articular head can rotate in the ulnar fossa, the radial fossa cooperates with the radial articular head and the radial articular head can rotate in the radial fossa, a sigmoid notch is provided on the side of the second base close to the ulna, and the sigmoid notch corresponds to the ulna.

[0013] The volar edge of the proximal fossa to the top edge of the volar side of the second base, and the dorsal edge of the proximal fossa to the top edge of the dorsal side of the second base are both set as wavy slopes B. The crests and troughs of slope B complement those of slope A. The setting of slope B is adapted to the ergonomic structure of the radiocarpal joint and conforms to the physiological range of motion of the wrist joint.

[0014] The proximal radius fixator is in the shape of a herringbone, and includes a first radius fixation plate, one end of which is connected to one end of the second radius fixation plate, and the first radius fixation plate and the second radius fixation plate form a herringbone shape. The first radius fixation plate and the second radius fixation plate are both provided with a plurality of second protrusions and a plurality of threaded screw holes, screws are provided in the screw holes, and the second protrusions are plugged into the second grooves.

[0015] The beneficial effect of the present invention is that the artificial wrist joint of the present invention can meet the physiological activity range of the normal human wrist joint, and is adapted to the ergonomic structural relationship of the middle wrist joint and the radiocarpal joint. In addition, the connecting parts can not only meet the physiological activity requirements of the wrist joint through plug-in connection, but also increase stability, reduce the risk of loosening, and prevent dislocation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a schematic structural diagram of the artificial wrist joint of the present invention;

[0017] Figure 2 is a side view of the artificial wrist joint of the present invention;

[0018] Figure 3 2. It is a schematic structural diagram of the distal carpal bone fixation component of the artificial wrist joint of the present invention;

[0019] Figure 4 2. It is a schematic structural diagram of the distal fossa of the artificial wrist joint of the present invention;

[0020] Figure 5 2. It is a schematic structural diagram of the distal joint head of the artificial wrist joint of the present invention;

[0021] Figure 6 It is a schematic structural diagram of the connecting member in the artificial wrist joint of the present invention;

[0022] Figure 7 Schematic diagram of the structure of the proximal joint head of the artificial wrist joint of the present invention;

[0023] Figure 8 Schematic diagram of the structure of the proximal fossa of the artificial wrist joint of the present invention;

[0024] Figure 9 It is a schematic structural diagram of the proximal radius fixator in the artificial wrist joint of the present invention.

[0025] In the figure, 1. distal carpal fixator, 2. distal glenoid fossa, 3. distal articular head, 4. connector, 5. proximal articular head, 6. proximal articular fossa, 7. proximal radius fixator, 8. screw;

[0026] 1-1. First carpal fixation plate, 1-2. Second carpal fixation plate, 1-3. First protrusion, 1-4. First screw hole;

[0027] 2-1. First base, 2-2. Glenoid fossa, 2-3. First groove;

[0028] 3-1. First joint head, 3-2. First connecting groove;

[0029] 5-1. Ulnar articular head, 5-2. Second connecting groove, 5-3. Radial articular head, 5-4. Ulnar section;

[0030] 6-1. Second base, 6-2. Second groove, 6-3. Ulnar glenoid fossa, 6-4. Radial glenoid fossa, 6-5. Sigmoid notch;

[0031] 7-1. First radial fixation plate, 7-2. Second radial fixation plate, 7-3. Second protrusion, 7-4. Second screw hole. DETAILED DESCRIPTION

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

[0033] The present invention provides an artificial wrist joint, the structure of which is as follows Figure 1 and 2 As shown, it includes a distal carpal bone fixator 1, a distal articular fossa 2 is inserted into the distal carpal bone fixator 1, a distal articular head 3 is arranged in the distal articular fossa 2, the distal articular head 3 is inserted into one end of a connector 4, the other end of the connector 4 is inserted into a proximal articular head 5, the proximal articular head 5 is arranged in a proximal articular fossa 6, a proximal radius fixator 7 is inserted into the bottom of the proximal articular fossa 6, and a locking screw 8 is connected on the distal carpal bone fixator 1 and the proximal radius fixator 7.

[0034] like Figure 3 As shown, the distal carpal bone fixator 1 is made of metal and includes a first carpal bone fixation plate 1-1. One end of the first carpal bone fixation plate 1-1 is connected to one end of the second carpal bone fixation plate 1-2. The first carpal bone fixation plate 1-1 and the second carpal bone fixation plate 1-2 form a "human" shape. The first carpal bone fixation plate 1-1 and the second carpal bone fixation plate 1-2 are both provided with a plurality of first protrusions 1-3 and a plurality of first screw holes 1-4. Screws 8 are provided in the first screw holes 1-4. A microporous coating is provided on the convex side of the distal carpal bone fixator 1 to facilitate bone ingrowth.

[0035] like Figure 4 As shown, the distal joint socket 2 is made of polymer material and includes a first base 2-1. The bottom of the first base 2-1 is provided with at least three first grooves 2-3, the first grooves 2-3 are plugged into the first protrusions 1-3, and a spherical joint socket 2-2 is provided on the first base 2-1.

[0036] like Figure 5 and Figure 6As shown, the distal joint head 3 includes a truncated spherical first joint head 3-1, and a first connecting groove 3-2 is provided on the truncated surface of the first joint head 3-1 to the center direction. The first joint head 3-1 cooperates with the joint socket 2-2 and can rotate in the joint socket 2-2. The first connecting groove 3-2 is plugged into the connecting member 4 and the connecting member 4 can slide up and down in the first connecting groove 3-2. The diameter of the first connecting groove 3-2 is 0.5 mm larger than the diameter of the connecting member 4 to facilitate the sliding of the connecting member 4. The depth of the first connecting groove 3-2 is greater than the radius of the first joint head 3-1;

[0037] The depth of the fossa 2-2 is greater than the radius of the first articular head 3-1. The palmar edge of the fossa 2-2 to the palmar top edge of the first base 2-1 and the dorsal edge of the fossa 2-2 to the dorsal top edge of the first base 2-1 are both set to a wavy slope A. The setting of the slope A, the radius of the first articular head 3-1, and the depth of the fossa 2-2 are adapted to the ergonomic structure of the middle wrist joint and conform to the physiological range of flexion and dorsiflexion of the middle wrist joint, with flexion reaching 48° and dorsiflexion reaching 23°.

[0038] like Figure 7 As shown, the proximal joint head 5 includes a truncated spherical ulnar joint head 5-1, and a second connecting groove 5-2 is provided from the truncated surface of the ulnar joint head 5-1 to the center of the circle. The second connecting groove 5-2 is plugged into the connecting piece 4. A spherical radial joint head 5-3 is provided on the side of the ulnar joint head 5-1 away from the ulna. The radius of the ulnar joint head 5-1 is larger than the radius of the radial joint head 5-3. An ulnar section 5-4 is provided on the ulnar side of the ulna head 5-1 to match the triangular bone.

[0039] The depth of the second connecting groove 5-2 is greater than the radius of the ulnar articular head 5-1. The centers of the ulnar articular head 5-1 and the radial articular head 5-3 are located in the same horizontal plane and do not overlap. The radii and height of the ulnar articular head 5-1, 5-3, and ulnar articular head 5-1 are designed to conform to the ergonomic structure of the radiocarpal joint and the physiological range of motion of the wrist joint. The apexes of the radial and ulnar articular heads 5-3 and 5-1 correspond to the two support points of the scaphoid and lunate bones on the radial surface of a normal wrist joint. The spherical curvature radius of the ulnar articular head 5-1 and radial articular head 5-3 at the proximal radial end of the dorsal radial 1 / 8 is greater than the curvature radius of other parts. The ulnar section 5-4 of the ulnar articular head 5-1 is adapted to the triquetrum.

[0040] like Figure 8As shown, the proximal joint fossa 6 is made of polymer material and includes a second base 6-1. The bottom of the second base 6-1 is provided with a plurality of second grooves 6-2. The second base 6-1 is provided with an ulnar joint fossa 6-3. The ulnar joint fossa 6-3 is provided with a radial joint fossa 6-4 on the side away from the ulna. The ulnar joint fossa 6-3 is connected to the radial joint fossa 6-4. The ulnar joint fossa 6-3 cooperates with the ulnar joint head 5-1 and the ulnar joint head 5-1 can rotate in the ulnar joint fossa 6-3. The radial joint The fossa 6-4 cooperates with the radial articular head 5-3 and the radial articular head 5-3 can rotate in the radial articular fossa 6-4. A sigmoid notch 6-5 is provided on the side of the second base 6-1 close to the ulna, and the sigmoid notch 6-5 corresponds to the capitulum of the ulna. The dorsal side of the second base 6-1 is provided with a number of protrusions and ligament reconstruction holes that imitate the dorsal side of the distal radius to accommodate the passage of the dorsal extensor finger and extensor wrist tendons and the need for ligament reconstruction. The ulnar side of the second base 6-1 has a sigmoid notch and ligament reconstruction hole for receiving the capitulum of the ulna.

[0041] The depth of the ulnar fossa 6-3 is greater than the radius of the ulnar articular head 5-1. The palmar edge of the proximal fossa 6 to the palmar top edge of the second base 6-1 and the dorsal edge of the proximal fossa 6 to the dorsal top edge of the second base 6-1 are both set to a wavy slope B. The crests and troughs of the slope B and the slope A complement each other, allowing the joint to reach the physiologically allowed range when in extreme flexion and extension without affecting each other, which can prevent the synovial membrane from being entrapped during extreme flexion and extension of the wrist joint. The setting of the slope B is adapted to the ergonomic structural relationship of the radiocarpal joint and conforms to the physiological range of motion of the wrist joint. The angle between the line connecting the crests of the proximal fossa 6 in the anteroposterior and lateral positions and the horizontal line conforms to the ulnar deviation angle and palmar inclination angle achieved by ergonomics.

[0042] like Figure 9 As shown, the proximal radius fixator 7 is made of metal and includes a first radius fixation plate 7-1. One end of the first radius fixation plate 7-1 is connected to one end of the second radius fixation plate 7-2. The first radius fixation plate 7-1 and the second radius fixation plate 7-2 form a "human" shape. The first radius fixation plate 7-1 and the second radius fixation plate 7-2 are both provided with a plurality of second protrusions 7-3 and a plurality of threaded screw holes 7-4. Screws 8 are provided in the screw holes 7-4. The second protrusions 7-3 are plugged into the second grooves 6-2. The convex side of the proximal radius fixator 7 is provided with a microporous coating to facilitate bone ingrowth.

[0043] The method for using the artificial wrist joint of the present invention is as follows: the distal carpal fixation member 1 is fixed to the carpal osteotomy surface by screws 8, that is, the first carpal fixation plate 1-1 and the second carpal fixation plate 1-2 are respectively fixed to the capitate bone and the trapezium and trapezium by screws 8; the proximal radius fixation member 7 is fixed to the radial osteotomy surface by screws 8, that is, the first radius fixation plate 7-1 and the second radius fixation plate 7-2 are respectively fixed to the radial osteotomy surface by screws 8; the first groove 2-3 on the distal articular fossa 2 is embedded in the first protrusion 1-3, and the second groove 6-2 on the proximal articular fossa 6 is embedded in On the second protrusion 7-3, the distal joint head 3 and the proximal joint head 5 are both connected to the connecting piece 4, the distal joint head 3 is placed in the distal joint fossa 2, and the proximal joint head 5 is placed in the proximal joint fossa 6. The length of the connecting piece 4 can be adjusted according to the wrist height and ligament tension. The distal joint head 3 can move in the distal joint fossa 2, and the proximal joint head 5 can move in the proximal joint fossa 6 to meet the physiological range of movement of the human wrist. The connecting piece 4 and the distal joint head 3 and the proximal joint head 5 can slide relative to each other, which can eliminate the pulling force when the human wrist lifts objects without acting on the joints.

[0044] The distal carpal fixator 1 and the proximal radius fixator 7 are fixed by screws 8, which reduces the risk of prosthesis loosening caused by shear force (adverse force) from lateral movement and converts most of it into a compressive force between the prosthesis and the bone surface, which is conducive to the ingrowth of bone cells. The fixation of the oblique screws resists the longitudinal pulling force and increases the stability of the prosthesis. The distal carpal fixator 1 allows for less carpal osteotomy, preserves the scaphoid tuberosity, and has little impact on the contents of the carpal tunnel.

[0045] Connector 4 is an insertable design, eliminating the longitudinal instability factor between components and between bone connections caused by wrist pulling force (adverse force); Connector 4 has a sliding characteristic, so that the longitudinal extension force when the wrist joint is pulled is dispersed and cannot act on a single point. The total depth of its insertion into the joint heads 3 and 5 is sufficient to exceed the length of the joint gap that can be extended when the wrist joint is pulled; the length of connector 4 can be adjusted according to the actual wrist height requirements, increasing the range of motion of the wrist joint within the allowable range, emphasizing the retention of the insertion points of all wrist dynamic tendons; thus, the stability of the wrist joint is enhanced, and the tension of the wrist muscles is restored due to the recovery of wrist height;

[0046] The diameter of the first connecting groove 3-2 is larger than that of the second connecting groove 5-2. The separation force of the joint gap caused by traction is mostly eliminated by the sliding between the connecting groove and the connecting member 4, thus avoiding the risk of dislocation.

[0047] The distal fossa 2 cooperates with the distal articular head 3, and the proximal fossa 6 cooperates with the proximal articular head 5, creating dual joint motion and a multi-dimensional motion axis. This creates two rotation points at the distal and proximal ends and a multi-directional rotation axis, bringing the prosthetic joint's motion closer to that of a physiological wrist joint. The connector 4 protrudes 3 to 5 mm between the first connecting groove 3-2 and the second connecting groove 5-2. The height between the two rotation axes effectively avoids the impact of soft tissue accumulation on actual joint motion in previous single-axis prosthesis designs. The distal fossa 2 allows the distal joint's range of motion to fall within the range of motion of the physiological mid-wrist joint. The proximal fossa 6 has different margins, deep and shallow on the palmar and dorsal sides, ensuring the range of motion of the radiocarpal joint after replacement. The wavy edges of the distal fossa 2 and proximal fossa 6 complement each other, allowing the entire prosthetic joint to move according to the designed physiological angle to meet physiological motion requirements while maintaining great stability, adapting to each other without interfering with each other. The combined dual-axis range of motion ensures normal physiological motion. Because the insertion points of the dynamic muscles of the wrist joint are mostly distal, the movement of the proximal joint axis is a secondary movement driven by the movement of the mid-carpal joint. The smaller lever arm reduces the possibility of excessive movement and the risk of dislocation. The structure of the proximal joint fossa 6 imitates the structure of the radio-scaphoid and radio-lunate joints, while increasing the range of motion, it increases the stability of the proximal support of the wrist joint. By setting the curvature radius of the spherical surface of the proximal joint head, the radiocarpal joint is tilted toward the dorsal radial side during dorsiflexion, which imitates the effect of flexion and extension of the scaphoid bone during wrist joint movement, and can complete a "dart throwing"-like action, making it closer to physiological activity.

Claims

1. An artificial wrist joint, characterized in that: The invention comprises a distal carpal bone fixing member (1), a distal joint fossa (2) is plugged into the distal carpal bone fixing member (1), a distal joint head (3) is arranged in the distal joint fossa (2), the distal joint head (3) is plugged into one end of a connecting member (4), the other end of the connecting member (4) is plugged into a proximal joint head (5), the proximal joint head (5) is arranged in a proximal joint fossa (6), a proximal radius fixing member (7) is plugged into the bottom of the proximal joint fossa (6), and threaded holes are provided on the distal carpal bone fixing member (1) and the proximal radius fixing member (7), screws (8) are threadedly connected in the threaded holes; The distal carpal bone fixing member (1) comprises a first carpal bone fixing plate (1-1), one end of the first carpal bone fixing plate (1-1) is connected to one end of the second carpal bone fixing plate (1-2), the first carpal bone fixing plate (1-1) and the second carpal bone fixing plate (1-2) form a "human" shape, the first carpal bone fixing plate (1-1) and the second carpal bone fixing plate (1-2) are both provided with a plurality of first protrusions (1-3) and a plurality of first screw holes (1-4), and screws (8) are provided in the first screw holes (1-4); The distal joint socket (2) comprises a first base (2-1), a plurality of first grooves (2-3) are arranged at the bottom of the first base (2-1), the first grooves (2-3) are plugged into the first protrusions (1-3), and a spherical joint socket (2-2) is arranged on the first base (2-1); The distal joint head (3) comprises a truncated spherical first joint head (3-1), a first connecting groove (3-2) is provided in the direction from the truncated surface of the first joint head (3-1) to the center of the circle, the first joint head (3-1) cooperates with the joint socket (2-2) and is rotatable in the joint socket (2-2), the first connecting groove (3-2) is plugged into the connecting piece (4), and the connecting piece (4) is movable up and down in the first connecting groove (3-2); The proximal joint head (5) comprises a truncated spherical ulnar joint head (5-1); a second connection groove (5-2) is provided from the truncated surface of the ulnar joint head (5-1) to the center of the circle; the second connection groove (5-2) is plugged into the connection piece (4); a spherical radial joint head (5-3) is provided on the side of the ulnar joint head (5-1) away from the ulna; the radius of the ulnar joint head (5-1) is greater than the radius of the radial joint head (5-3); an ulnar section (5-4) is provided on the side of the ulnar joint head (5-1) close to the triangular bone; the ulnar section (5-4) is adapted to the triangular bone; The exposed length of the connecting piece (4) between the first connecting groove (3-2) and the second connecting groove (5-2) is 3 to 5 mm.

2. The artificial wrist joint according to claim 1, characterized in that: The proximal joint socket (6) comprises a second base (6-1), the bottom of which is provided with a plurality of second grooves (6-2), an ulnar joint socket (6-3) is provided on the second base (6-1), a radial joint socket (6-4) is provided on the side of the ulnar joint socket (6-3) away from the ulna, the ulnar joint socket (6-3) is communicated with the radial joint socket (6-4), the ulnar joint socket (6-3) cooperates with the ulnar joint head (5-1), and the ulnar joint head (5-1) can rotate in the ulnar joint socket (6-3), the radial joint socket (6-4) cooperates with the radial joint head (5-3), and the radial joint head (5-3) can rotate in the radial joint socket (6-4), and a sigmoid notch (6-5) is provided on the side of the second base (6-1) close to the ulna, and the sigmoid notch (6-5) corresponds to the capitulum of the ulna.

3. The artificial wrist joint according to claim 2, characterized in that: The proximal radius fixing member (7) comprises a first radius fixing plate (7-1), one end of the first radius fixing plate (7-1) is connected to one end of a second radius fixing plate (7-2), the first radius fixing plate (7-1) and the second radius fixing plate (7-2) form a "human" shape, the first radius fixing plate (7-1) and the second radius fixing plate (7-2) are both provided with a plurality of second protrusions (7-3) and a plurality of second screw holes (7-4), the second screw holes (7-4) are provided with screws (8), and the second protrusions (7-3) are plugged into the second grooves (6-2).

Images